Hochbau Bâtiment Buildings

Hochbau

Bâtiment

Buildings Die Sporthallen Mülimatt in Brugg Sports hall Mülimatt, Brugg

Massimo Laffranchi, Armand Fürst

Fig. 1 Ansicht der Faltwerkstruktur mit verglasten Flächen an den Stirn- und Längsseiten. View of the folded-plated concrete structure with glazed facades at the front and longitudinal sides. (© Kanton Aargau, Foto: René Rötheli, Baden).

Einleitung Introduction und den auf Aare- und Bahnseite Das neue Sportausbildungszent - The new sport facility with two unterschiedlich hohen Längsfas sa - rum mit zwei Dreifachturnhallen, triple gyms together with several den ein einheitliches Erscheinungs- diversen kleineren Turnhallen minor gyms and classrooms as bild. Die Dachträger stabilisieren und Sporträumen, Unterrichtsräu - well as an outdoor sports field die verglasten Stirnflächen. Das men sowie Sportaussenplätzen was built in a single location monolithische Betontragwerk wurde an einem einzigen Stand- giving appropriate consideration wirkt ausserdem als wetterfeste, ort beim Naherholungs gebiet an to the recreational area along the gefaltete Haut. Die Wärme - der Aare in Brugg erstellt. river Aare. dämmung im Dachbereich ist in Das Gebäude ist aufgrund des Due to the distinctive location and der heruntergehängten Decke exponierten Standorts, seiner its striking external dimensions, integriert, die an den Dach - beachtlichen Abmessungen und the building is an eye-catcher for trägern befestigt ist. Die Stiele der Nähe zum Bahndamm ein rail travellers. This consideration, schützen und beschatten ihrerseits Blickfänger für die Bahnreisen- as well as the need for an effi- die verglasten Flächen der Längs- den. Diese Feststellung sowie das cient and light structure resulted fassaden. Das Regenwas ser wird Bestreben, ein effizientes und in a thin-walled, folded-plate con- in den Rinnen der Dachfalten leichtes Tragwerk zu realisieren, crete shell structure that encloses gesammelt und entlang der um die freie Spannweite der all the sports and teaching facili- Stielflächen abgeleitet (Fig. 2). ungeteilten Dreifachhallen von ties (Fig. 1 and 3). It rises from 50 m zu überbrücken, führte zum two different ground levels and Konzepte für das vorfabri- Entwurf einer dünnwandigen, extends over the roof surface and zierte Faltwerk gefalteten Betonschale, die alle the longitudinal facades. The gla- Während die Fundationen, das Sport- und Unterrichtsräume um- zed faces at the front of the buil- Tragwerk des erdberührten Sockel - hüllt (Fig. 1 und 3). Das auf die ding are stabilised by the front geschosses sowie sämtliche De- Gelände neigung abgestimmte, roof beams. Further, the monolit- cken und Einbauten der Sport- asymmetrische Faltwerk in Sicht- hic concrete structure distinguis- halle vor Ort betoniert wurden, beton verleiht der Dachfläche hes the sports hall and acts as a besteht die darüber gespannte

42 weatherproof folded membrane. Faltwerkstruktur aus Betonfertig - The ceiling within the thermal teilen. Im Werk liessen sich wirt- insulation is fixed to the bottom schaftlich optimierte Lösungen of the roof beams, whilst the und eine hohe Ausführungs - column beams protect and shade qualität durch den Einsatz von the glazing on the long side of selbstverdichtendem Beton und the building. Rainwater is collec- der Vorspanntechnologie erzie- ted in the roof folds and runs len. Kleine Spannglieder mit be- along the surface of the column sonderen, schmalen Endveranke- beams, which function as drain run gen in den Rahmenecken er - gutters as a result of their shape möglichten dünnwandige, vorge- (Fig. 2). spannte Faltwerkscheiben, ohne das angestrebte Erscheinungsbild Description and design of der Sichtbetonflächen zu beein- the prefabricated structure flussen. Die Fertigteile wurden so As opposed to the foundations, gross wie möglich gewählt, um the underground structure as die Anzahl der Ortbetonfugen zu well as the floor slabs and walls of minimieren. Die Grenzen betref- the sports hall, which are made of fend Grösse und Gewicht setzten in-situ concrete, the folded-plate die Einrichtungen zur Handha - frame structure is realised in pre- bung der Elemente im Werk und cast concrete. Thus, the most cost- die Bedingungen für den Stras - effective solution and high execu- sen transport. Die 27 kürzeren Fig. 2 Die äusseren Stielflächen wirken auch als tion quality can be guaranteed by Stiele der südlichen Fassade auf Rinnen für das abfliessende Regenwasser taking advantage of self-compac- der Bahnseite sind 11,1 m lang Längsseiten. und 35 t schwer. Jene der nördli- ting concrete technology and of The columns function as drain gutters. the possibilities given by the post- chen Fassade auf der Aareseite (© Studio Vacchini Architetti, Locarno). tensioning method. The thickness weisen eine Länge von 14,3 m of the structural members is re- und ein Gewicht von 43 t auf. Die duc ed to a minimum, allowing 81 Dachträgerelemente weisen placement of small tendons in the eine konstante Länge von 16,3 m section and their anchorages in und ein Gewicht von 49 t auf. Bauherrschaft the frame corners, without alter- Die Stiel- und Dachträgerele men - Kanton Aargau, vertreten durch die Immobilien Aargau, Departement ing the appearance of the fair- te werden durch bewehrte Ort- Finanzen und Ressourcen, und faced concrete structure. The size betonfugen und eine nach der Stadt Brugg of the elements is chosen to mini- Montage eingezogene Dachvor- Planungsteam Bauingenieur: Fürst Laffranchi mise the total number of joints. span nung zu 27 monolithischen Bauingenieure GmbH, Wolfwil; Element weight and length is Rahmeneinheiten mit einer Spann - Architekt: Studio Vacchini Architetti, limited by the handling in the weite von 52,6 m miteinander Locarno; Landschaftsarchitekt: Paolo Bürgi, Camorino production facility and by the verbunden. Die 30 mm breiten Ausführung conditions for road transporta- Spaltfugen entlang der Dach - Arigon Generalunternehmung AG, tion. The 27 shorter column beam kante zwischen den Rahmenein - Zürich mit den Subunternehmern Element AG, Veltheim (Betonvorfa- elements on the railway side have heiten werden mit Mörtel vergos- bri kation); VSL (Schweiz) AG, Subin- a length of 11.1 m and a weight sen und mit verschweissten Stahl- gen (Vorspanntechnik); Jäggi AG, of 35 t. Those on the river side bauteilen mechanisch verbunden. Brugg (Baumeisterarbeiten) have a length of 14.3 m and a Dadurch wird eine Schalenwir - weight of 43 t each. The 81 roof kung der Dachfläche für die ver- beam elements have a constant änderlichen Einwirkungen erzielt Owner length of 16.3 m and a weight of (Fig. 7). Sämtliche Fertig teile wei - Canton Aargau, represented by the Immobilien Aargau, Department of about 49 t. sen eine Querschnittshöhe von Finance and Resources, and Brugg The roof- and column-beam ele- 2,59 m und eine konstante Breite Planning team ments are connected by in-situ von 2,93 m auf. Die mittlere Civil engineers: Fürst Laffranchi Bauingenieure GmbH, Wolfwil; concrete joints and internal post- Stärke der Dachstruktur, bezogen Architect: Studio Vacchini Architetti, tensioning tendons to form 27 auf die Grundrissfläche, beträgt Locarno; Landscape architect: Paolo monolithic ‘frame units’ (FU) with lediglich 0,37 m. Bürgi, Camorino Execution a span of 52.6 m. The 30 mm wide Die Rahmeneinheiten stabilisie- Arigon Generalunternehmung AG, gaps between the FUs are grout- ren das Gebäude in Querrichtung. Zurich (main contractor) with the ed by a special cement grout. Die am Rahmeneck unter Dach subcontractors Element AG, Veltheim (prefabricated concrete); VSL (Schweiz) Additionally, welded steel plates angeordneten Diagonalscheiben AG, Subingen (post-tensioning); Jäggi along the roof ridge provide a werden durch ein in Längsrich - AG, Brugg ( construction work) rigid connection and enable the tung durchgehendes, horizonta-

43 Fig. 3 Ansicht der Sporthallen von der Aareseite: Das durchgehende Foyer unterhalb der zwei Dreifachhallen ist gut erkennbar. View of the sports hall from the river side: the foyer underneath the two triple gyms is recognisable. (© Kanton Aargau, Foto: René Rötheli, Baden).

les Zugglied verbunden (Fig. 9). desired shell action for live loads fen. Die kleinen Spannglieder im Dadurch wird die Form des (Fig. 7). The precast roof and Verbund mit maximal 6 Litzen

Faltwerkdachs erhalten und die column beams have a constant und einer Vorspannkraft bis P0 = Stiele wirken als Teile eines über section height of 2.59 m and a 1,1 MN finden innerhalb der die gesamte Gebäudelänge auf- constant width of 2.93 m. The Dach- und Stielscheiben Platz gespannten Rahmens, der die average thickness of the roof (Fig. 5). Die Breite der festen Längsstabilisierung sicherstellt. structure related to the covered Der Horizontalschub der Rahmen- horizontal surface is 0.37 m. einheiten wird durch die vorge- The FUs guarantee the stability of spannte Deckenplatte des Sport- the structure in the transverse hallenbodens aufgenommen, die direction. In the longitudinal somit auch als Zugglied wirkt (Fig. direction, the diagonal panels at 4). Die bei jedem Stiel angeordne- the frame corners (Fig. 9) are con- ten Ortbetonpfähle sind an ihrem catenated and accommodate a Kopf in ein steifes Bankett einge- continuous tension tie that ensu- bunden und übertragen die verti- res the folded form. In addition, kalen Kräfte in die untere, steife- they connect the column beams re Kies schicht. Jeder Pfahl weist at the top to a continuous multi- einen Durchmesser von 0,80 m ple frame, which guarantees the und eine Länge zwischen 7,0 und longitudinal stability. 11,0 m auf. Das Ortbetontrag - The thrust of every FU is equili- werk ist unabhängig vom Falt- brated by a tie connection to the werk der Hallen in der oberen, post-tensioned concrete slab of mittelsteifen Kiesschicht flach the gym floor (Fig. 4). Thus, only fundiert. Setzungsdifferenzen bis vertical forces have to be carried zu 20 mm lassen sich durch die from each column to the underly- schlanken Verbindungen aus rost- ing compact gravel layer by a sin- freien Zug stäben zwischen den gle concrete pile. All piles have a Stielen und der Sporthallendecke diameter of 0.80 m and variable aufnehmen. lengths between 7.0 and 11.0 m. In order to reduce the risk of pos- Tech nologie und sible differential pile settlements, Fig. 4 Spannglieder und deren Konstruktives a rigid foundation beam (pile Verankerungen im Stiel und im Vorspannung cap) connects the piles at the top. anschliessenden Dachträgerelement Das Konzept für die Vorspannung The in-situ sports hall structure is sowie Zugverbindung zwischen Stiel des Faltwerks wurde ausgehend founded independently in the und Sporthallendecke. von der gewünschten Tragwerks- upper gravel layer on a ground Tendons and anchorages in column form und mit Rücksicht auf die slab. Relative settlements of up to and roof beams, tension ties connec- dünnwandigen Bauteile entwor- 20 mm can be accommodated by ting the column with the gym slab.

44 Fig. 5 Längsschnitt und Querschnitte einer Rahmeneinheit mit Elementeneinteilung, Ortbetonfugen und Spanngliedern. Longitudinal and cross sections of a frame unit (FU) showing the precast roof and columns beams, the cast-in-situ joints and the post-tensioning tendons.

the slender stainless tie bars con- Anker in den Rahmenecken wurde the whole structure and concret- necting the column beams to the eigens für das Projekt minimiert. ing of the joints in situ. The gym’s floor slab. Die vorfabrizierten Stiele wurden strands were inserted in the ducts im Werk vorgespannt (Fig. 10). and stressed at intermediate an- Technology and detailing Die vorkonfektionierten Spann- chorages located in block-outs on Post-tensioning glie der à 4 Litzen für den End - the roof ridge, which were subse- The conceptual design for the zustand sowie zusätzliche Mono- quently filled with concrete and post-tensioning was developed litzenspannglieder ohne Verbund are not visible in the final state taking into account the desired für die Transport- und Montage - (Fig. 11). All cross sections are structural form and the thin-wall - phase wurden aus einer Spann- compressed under dead and live ed structural members. The nische am Stielfuss aktiviert. Die loads: the average concrete com- grout ed tendons are small sized Dachspannglieder wurden erst pression stress due to post-ten- σ with up to 6 strands and a pre- nach der Montage der Dachträ- sion ing is c,End = – 4.6 MPa. stressing force of P0 = 1.1 MN, in gerelemente auf provisorischen order to fit into the member sec- Türmen und dem Beto nie ren Self-compacting concrete tions (Fig. 5). They require little respektive Vergiessen der Quer- All prefabricated elements are space in the frame corner for the und Längsfugen konfektioniert. made of the same high-strength dead-end anchorages, spe cially Die Litzen wurden in die self-compacting concrete (SCC) of developed for this project. The Hüllrohre eingestossen und aus the strength class C50/60. The ele- prefabricated column beams einer Spannnische auf der Dach- ments – with V- and Y-shape – were post-tensioned at the facto- oberseite mit kompakten Zwi- were casted upside down to ensu- ry (Fig. 10). Stressing of the ten- schen veranke rungen gespannt. re both optimal filling of the dons was carried out from the Die Nischen wurden anschlies- formwork from above and a best- column base, where the live send ausbetoniert und sind im possible compact surface without anchorages are located in a com- Endzustand nicht erkennbar (Fig. air occlusions on the upper and mon block-out. Supplementary 11). Sämtliche Querschnitte sind outer faces of the members. For monostrand tendons had to be unter den ständigen und den ver- the same reasons, the maximum provided for the construction änderlichen Einwir kungen vorge- aggregate size was reduced to 8 phase. On the other hand, the spannt. Die mittlere Betondruck- mm. The fair-faced concrete sur- precast roof beams were post- spannung aus der Vorspannung faces are protected by hydropho- σ tensioned only after erection of beträgt c,Ende = – 4,6 MPa. bic impregnation. The directly

45 Fig. 6 Fig. 7 Fig.8 Gerüsttürme für die temporäre Nischen und Stahlplattenverbindung Rostfreie Zugglieder für die Abstützung der Dachträger. in den 3 cm breiten Längsfugen an Verbindung zwischen Stiel und Temporary support of the roof beams der Dachoberkante. Sporthallendecke. using falsework. Block-outs for welding plate connec- Stainless ties between the gym slab tions in the 3 cm-wide gap on the and one column beam. roof ridge.

Selbstverdichtender Beton rain exposed sides are treated die unabhängig voneinander fun- Sämtliche Fertigteile wurden aus with a supplementary transpa- diert sind, mussten so entworfen dem gleichen hochfesten, selbst- rent sealing. The roof surfaces are werden, dass sie Ausführungsto - verdichtenden Beton (SVB) der protected by a UV-resistant poly- le ranzen und Differenzialsetzun - Festigkeitsklasse C50/60 herge- urethane liquid membrane. gen aufnehmen können. Die rost- stellt. Die Fertigteile für Dach und freien Zugglieder (D = 40 mm), Stiele mit V- respektive variablem Structural details die den Horizontalschub von Y-Querschnitt wurden mit den The connections between the jedem Stiel zur Sporthallendecke Sicht flächen nach unten beto- precast members and the in-situ übertragen, wurden vorgängig in niert, um die Schalung aus den concrete structure had to be de- Rohreinlagen der Decke einge- Einfüll punk ten auf der Oberseite sign ed to take into account the führt und nach Errichten des optimal zu verfüllen und damit estimated differential settlements Stiels mit einem Muffenstoss an- die im End zustand dem Regen and placement inaccuracies. The geschlossen (Fig. 8). Ein freier und Wasserabfluss ausgesetzten stainless tension ties (D = 40 mm) Zwischenraum von 20 mm um Betonflä chen möglichst kompakt that transfer the thrust of every den Stab ermöglicht allfällige und frei von Lunkern auszubil- frame unit to the gym’s floor slab, Differenzialsetzungen. Stiel und den. Aus den gleichen Gründen were previously inserted into tu- Fundations ban kett werden durch beträgt das Grösstkorn lediglich 8 bular openings placed in the slab, das Verschweis sen von eingeleg- mm. Sämtliche Sichtbetonflächen then connected to the column ten Stahlplatten bei der Montage sind durch eine Tiefenhydro - beams after their erection (Fig. 8). verbunden. Die schmale Fuge phobie rung geschützt. Die direkt A 20 mm space all around the tie zwischen Stielfuss und der Funda- dem Regen ausgesetzten Stiel- allows for settlements. mentaussparung wird anschlies- flächen sind zusätzlich durch eine The base point connection of the send durch einen hochfesten farblose Versiegelung geschützt. column beams is realised by corres- Vergussmörtel verfüllt. Die Aus- Auf der Dachaufsicht wurde voll- ponding steel plates encased in führungs tole ranzen wurden vor- flächig eine UV-resistente Flüssig- the column and in the foundation gängig durch das Nivellieren der kunststoffabdichtung auf Poly - beam, which were welded during Einlagen im Bankett und bei Be - urethanbasis aufgebracht. erection. The gap between the darf mit Schiftplatten ausgegli- column base and the foundation chen. Konstruktive Durchbildung was grouted afterwards by a Die Verbindungen zwischen dem high-strength cement grout. In - Herstellung vorfabrizierten Faltwerk und dem accuracies were compen sated in Für die Herstellung der kurzen Ortbetontragwerk der Einbauten, advance through levell ing and if und langen Stiele sowie für die

46 Fig.9 Fig. 10 Fig. 11 Zugglieder in der Diagonalscheibe Vorspannung der Stiele im Werk, Vorspannung der Dachträger auf der unter Dach im Rahmeneck vor dem Ankernische und Stahl-Fussplatten. Baustelle dank Betonieren der Aussparung. Post-tensioning of the column beams Zwischenverankerungen an der Tension tie in the diagonal panel at at the factory, block-out and steel Dachaufsicht. the frame corner before concreting. base plates. Post-tensioning of the roof beams in (© VSL AG, Subingen). situ by means of intermediate anchorages. (© VSL AG, Subingen).

necessary by means of supplemen- mittleren respektive die seitlichen Autoren/Authors tary steel plates. Fertigteile des Dachs waren insge- Massimo Laffranchi samt vier Schalungen erforder- Dr. sc. techn., dipl. Bauing. ETH [email protected] Construction lich. Die vier Elementtypen konn- The short and long column beams ten daher parallel in einem einzi- Armand Fürst as well as the midspan and lateral gen Werk in Zyklen von zwei bis Dr. sc. techn., dipl. Bauing. ETH [email protected] roof beams all required their spe- drei Tagen pro Bauteil produziert cific steel formwork. Thus, the werden. Die Betonmischung wur - Fürst Laffranchi Bauingenieure GmbH four element types were manu- de für eine rasche Festig keits ent - CH-4628 Wolfwil factured simultaneously in one wicklung optimiert. Das Drehen factory and in a work cycle of 2 to der schweren, auf der Kopfseite 3 days per element. The concrete betonierten Fertigteile erforderte composition was optimised to eine besondere Drehvorrichtung. achieve a rapid development of Montiert wurden die Fertigteile strength. The rotating of the mithilfe eines 500-t-Raupenkrans, heavy elements, which were cast der neben der Sporthalle zusam- upside down, required a special mengebaut worden war. Die Dach- mechanism. träger wurden bis zu ihrer Vor- The handling and assembling of spannung von Gerüsttürmen ge- the precast elements was carried tragen (Fig. 6). Diese wurden über out with the aid of a 500 t craw- ein System von hydraulischen ler crane placed beside the hall. Pressen abgesenkt, deren Kräfte The roof beams were carried by sich fein steuern liessen. Die temporary falsework until the Errichtung des Faltwerks in zwei post-tensioning was completed. Phasen erforderte insgesamt vier The lowering of the falsework Mona te, die Kosten der Sporthalle was controlled by a system of in klu sive Ausbau und technischer hydraulic jacks. The erection of Ausrüstung betragen 25 Millio - the large span structure required nen Franken. a total time of 4 months. The costs for the sports hall inclu- sive of technical equipment are of 25 million Swiss Francs.

47 Une nouvelle toiture pour le Musée Olympique à Lausanne A new roof for the Olympic Museum at Lausanne

Aurelio Muttoni

Introduction Introduction Système porteur Dans le cadre de l’agrandissement As part of upgrading and extend- La structure est une grille de pou- du Musée Olympique à Lausanne ing the Olympic museum in Lau - tres à trame régulière. 96 sommiers (Suisse), une nouvelle toiture a sanne a new roof was built to transversaux de 18 à 21 m de lon - été construite sur l’ancien bâti- cover the existing building (finish - gueur, une hauteur de 1,00 m et ment réalisé en 1990. La structure ed in 1990). The new roof also un espacement de 0,75 m sont de cette toiture, fonctionnant acts as an unusual canopy, shad - suspendus à des poutres métalli- aussi comme brise-soleil sur sa ing natural light in the south part ques longitudinales couvrant les partie sud, est une grille de pou- of the building. It consists of a 71,25 m de longueur (Fig. 2a). Ces tres en béton fibré à ultra-hautes grid of beams cast in ultra-high dernières sont appuyées sur des performances. Une comparaison performance fibre-reinforced con - murs en béton et sur des colonnes avec d’autres options (bois lamel- crete (UHPFRC). A comparison métalliques. Sur la partie sud orien- lé-collé, aluminium extrudé) a with other options (timber and tée vers le lac, les sommiers trans- démontré que ce matériau peut aluminium members) showed the versaux sont en porte-à-faux sur être intéressant si tous les aspects UHPFRC solution to be the most une longueur de 4,50 m jusqu’à sont considérés (économie, dura- competitive when considering all 9,00 m (Fig. 2b). La partie nord sur bilité, facilité d’exécution, aspect requirements of the structure le restaurant et une partie au sud architectural, poids et délais (economy, durability, ease of con- de la façade vitrée sont couvertes d’exécution). Des éléments de struction, architectural expression, par une tôle à profil trapézoïdal grandes dimensions (longueurs weight and construction details). qui assure le contreventement jusqu’à 21 m) ont pu être réalisés The long lengths of the beams horizontal. A l’extrémité sud en assemblant éléments plus (up to 21 meters) were obtained fonc tionnant comme brise-soleil, courts par la technique des joints by assembling shorter members la tôle est remplacée par des pou- conjugués et de la précontrainte using the match casting techni- tres longitudinales espacées de par post-tension. En outre, le que in combination with post- 0,75 m et de 0,55 m de hauteur BFUHP permet de réaliser des élé- tensioning. In addition, the use of appuyées sur les porte-à-faux ments durables malgré leurs fai- UHPFRC allowed the manufacture fonctionnant comme raidisseurs et bles dimensions et leur élance- of durable elements, despite the s’opposant ainsi au déversement ment. limited thickness used and the des sommiers transversaux. Les pronounced slenderness of the sections de tous les éléments sont Le Musée Olympique et sa beams. trapézoïdales avec largeurs varia- nouvelle toiture bles entre 80 et 100 mm. Puisque Le Musée Olympique, réalisé en The Olympic Museum and la partie en porte-à-faux des som- 1990 sur la rive du Lac Léman à its new roof miers transversaux se situe à l’ex- Lausanne, est devenu avec le The Olympic Museum was built in térieur, un joint en proximité de temps le musée le plus fréquenté 1990 at the shores of Lake la façade Sud a dû être disposé de la ville. La fréquentation Geneva and today it is already the pour les séparer thermiquement accrue ainsi que des nouvelles exi- most frequently visited museum de la partie à l’intérieur. Ce joint gences muséales ont rendu néces- in Lausanne. It was decided to thermique est conçu pour repren- saire un agrandissement et la réa- upgrade and extend the museum dre l’effort tranchant et le mo- lisation d’une nouvelle toiture sur due to the large number of visits ment de flexion qui sont maxi- l’ancienne terrasse afin d’abriter per year and at the same time to maux à cet endroit. Certains som- un nouveau restaurant et une implement a number of new re- miers transversaux entièrement à nouvelle salle de banquets. Sur la quirements for museums. An im- l’extérieur ont une longueur in - partie sud, la nouvelle couverture portant part of the project was to interrompue de 21 m. Les autres, fonctionne aussi comme brise-sol- build a new roof over the existing interrompus par le joint thermi- eil. La nouvelle structure couvre terrace to accommodate a new que, ont une portée variable toute la partie du bâtiment orien- restaurant. On its south part, the entre 9,00 et 13,50 m à laquelle tée vers le lac sur un front de new roof also acts as a canopy, s’ajoute le porte-à-faux au-delà 71,25 m et une largeur de 21,00 m shading natural light. The new du joint (Fig. 2b). (Fig. 1). Les travaux ont eu lieu structure covers the part of the Lors de la phase initiale du projet, entre janvier 2012 et septembre building facing the lake with a plusieurs options ont été étudiées 2013. total length of 71.25 m and a pour ce qui concerne la matériali-

48 (a)

(b)

(c)

Fig. 1 a) Façade sud du Musée Olympique et nouvelle toiture pendant les travaux, b) vue vers le lac depuis l’intérieur et c) vue de la partie fonctionnant comme brise-soleil. a) South facade of the Olympic Museum and new roof during construction, b) view towards the lake, and c) view of the canopy.

49 (a) A 21.000

A 71.250

(b)

Fig. 2 a) vue en plan et b) schéma d’une poutre transversale avec portée de 13,50 m et porte- à-faux de 4,50 m (coupe A–A dans la vue en plan). a) plan view and b) view of a transverse beam with a span of 13.50 m and a cantilever of 4.50 m (cross section A–A in plan view).

sation (BFUHP, bois lamellé collé, width of 21.00 m (Fig. 1). The est composé de deux tubes en aluminium extrudé). En considé- work was started in January 2012 acier inoxydable dans lesquels rant tous les aspects économiques and finished in September 2013. trouvent place les deux torons (coûts de production et d’entre- dans la partie supérieure tendue. tien), techniques (complexité des Structural system Ces tubes, avec les gaines des détails constructifs), exécutifs The structure of the roof consists câbles de précontrainte, ont été (facilité de montage et possibilité of a regular grid of beams. In the injectés par coulis de ciment après d’assurer les délais), de durabilité transverse direction, the beams mise en tension des câbles sur le et architecturaux, l’option en have a length varying between 18 chantier. Dans la partie inférieure BFUHP a été retenue. and 21 m. They are 1.00 m in des sommiers, la force de com- height and are spaced at 0.75 m. pression est reprise par des pla- Préfabrication, montage et These beams are suspended from ques en acier inoxydable soudé. détails constructifs steel girders covering the 71.25 m La fixation des raidisseurs sur les Les éléments en BFUHP ont été length of the roof (Fig. 2a). The sommiers transversaux a été faite préfabriqués dans une usine située steel girders are supported on par le biais de plaques en acier à environ 80 km du chantier. Pour concrete walls and steel columns. inoxydable fixées aux raidisseurs faciliter le décoffrage des moules In the south part, facing the lake, par des tiges lors du bétonnage métalliques (Fig. 4a), les sections the transverse beams have canti- (Fig. 4a et 4b). Lors du montage, des sommiers et des raidisseurs levers ranging from 4.50 m to les plaques ont été boulonnées sont trapézoïdales avec épaisseurs 9.00 m (Fig. 2b). To ensure lateral sur les sommiers inférieurs par le variables entre 80 et 100 mm. A stability, the north part (over the biais d’écrous vissés sur des tiges cause de l’élancement des élé- restaurant) and some regions of filetées en attente (Fig. 3d). Le ments, pour faciliter le transport et the south part are covered by a même détail a été utilisé pour le montage, les sommiers de 21 m steel sheet of trapezoidal shape. suspendre les sommiers transver- de longueur ont été fabriqués et This steel sheet is replaced in the saux aux poutres métalliques lon- transportés en deux pièces de outermost south regions by longi- gitudinales (Fig. 4c). 10,50 m (Fig. 3b) et assemblées tudinal stiffeners, spaced at 0.75 m La résistance à la flexion des som- sur place au droit de joints conju- and with a height of 0.535 m, miers transversaux est assurée gués précontraints par deux supported on the cantilevers and essentiellement par les torons câbles mono-torons post-tendus acting as diaphragms (to resist post-tendus. Afin de permettre la (Fig. 3c). Pour les autres sommiers, lateral instability of the transver- fixation des gaines vides lors du le joint thermique a fait office de se beams). All sections were tra- bétonnage, des barres de montage joint conjugué (Fig. 4c). Ce joint pezoidal-shaped with a thickness dans le sens transversal et longi-

50 varying between 80 and 100 mm. tudinal ont été utilisées. A ces ar- (both production and maintenan- Taking into account the fact that matures s’ajoutent les tiges verti- ce), technical aspects (complexity the cantilevers are exposed to cales nécessaires pour les fixations of construction details), construc- environmental conditions in the des éléments et la suspension des tion technique (ease of construc- south part, a joint was provided sommiers (Fig. 4a et 4b). tion and limited construction close to the south façade for ther- Les raidisseurs longitudinaux ont time), durability issues and/or mal insulation purposes. This joint la même largeur (80–100 mm) architectural needs, UHPFRC was transfers the shear and bending mais sont de moindre hauteur finally selected. moments, which are highest at (535 mm) et leur longueur varie this region, of the transverse entre 3,00 et 12,00 m. Ils ont été Precasting, erection and beams. Some of the transverse coulés de la même façon et la detailing beams have a length of 21 meters résistance à la flexion des élé- The UHPFRC members were pre- without joints. The others are not ments dépassant une certaine cast in a specialized factory locat- continuous (with the thermally longueur est assurée par deux ed 80 km from the construction insulating joint), have inner spans torons prétendus en usine (mé- site. In order to enhance the ease ranging from 9.00 to 13.50 m (Fig. thode des fils adhérents). of demoulding (Fig. 3a), the cross- 2) and are followed by the canti- sections of the beams were trape- lever region. Caractéristiques du BFUHP zoidal with varying thicknesses During the design of the structu- et dimensionnement between 80 and 100 mm. Due to re, several options regarding the Le «béton spécial industriel» (BSI® the slenderness of the members, material to be used for the roof avec 200 kg/m3 de fibres métal - and to improve transportation and were investigated (UHPFRC, tim- liques, lf = 20 mm, øf = 0,3 mm) a erection of the beams, the beams ber, extruded aluminium). Taking été utilisé pour tous les éléments with a total length of 21 meters into account economic aspects en BFUHP. Aucun traitement ther- were fabricated as two pieces of

(a) (b)

Fig. 3 a) préparation du coffrage métallique, b) manutention en usine des éléments de 10,50 m de longueur, c) joint conjugué des sommiers de 21 m et d) montage des raidisseurs longitudinaux sur les sommiers transversaux. a) arrangement of steel formwork, b) handling of the 10.50 m elements, c) match-casted joint for the 21 m beams and d) erection of longitudinal stiffeners over the transversal beams.

51 (a) (b) (c) pre-stressed strand ø 15.7 mm 80 2 threaded bars M12 steel longitudinal beam pre-stressed strand 2 threaded bars M12 supported by steel columns

ø 15.7 mm 500 stainless steel tubes with injected reinforcement 100 FLA 80 x 20 post-tensiong strands inside bar ø 18 mm stainless steel 100 strand ø 15.7 post-tensioned

2 threaded bars M12 190

1000 strand ø 15.7 1000 2 threaded bars M12 post-tensioned 6 reinforcement bar ø 18 mm 80 stainless steel plates steel column

Fig. 4 a) et b) détail de la fixation des raidisseurs supérieurs sur les sommiers transversaux en dessous et c) détail du joint thermique et de la suspension des sommiers transversaux sur les sommiers métalliques longitudinaux. a) and b) detail of joint between longitudinal and lower transversal beams and c) detail of thermally insulating joint and of the suspension of transverse beams from the steel beams.

mique n’a été appliqué lors du 10.50 m each (Fig. 3b). These pie- dimensionnées selon les règles bé tonnage. La conformité du bé - ces were later assembled at the classiques pour reprendre la tota- ton a été contrôlée par des essais construction site by means of the lité des efforts de traction à l’état de compression sur cubes coulés match-casted joints and post-ten- limite ultime dus à la flexion, à (100x100x100 mm), par des essais sioning (monostrand) tendons l’effort tranchant et à la diffusion de traction sur carottes (ø = 50 mm, (Fig. 3c). For the other beams, the dans le plan due aux forces con- l = 200 mm) prélevées d’un som- thermally insulating joint was centrées (forces d’ancrage des mier d’essai et par essais de flexion used as a match-casted joint (Fig. câbles post-tendus et forces intro- sur prismes (90x90x400 mm) dé- 4c). This joint consisted of two duites par les joints thermiques). coupés du même élément (4 pris- tubes in stainless steel, where the La résistance assurée par les fibres mes dans le sens vertical et 4 dans two monostrand tendons were a par contre été considérée pour le sens longitudinal) ou coulés sur located (in the tension side of the place. member). These tubes, together Les essais ont montré une variabi- with the ducts, were grouted lité relativement faible pour ce with mortar after post-tensioning Equipe/Team qui concerne la résistance à la com- the strands. In the bottom side, Client/Owner pression après 28 jours (valeur the compression forces are trans- CIO, Comité International Olympique, Lausanne moyenne = 188 MPa, écart type = ferred by means of welded stain- Architecture 9,8 MPa à 28 jours) et la résistan- less steel plates. B+W architecture sàrl, ce à la traction de la matrice ci- Assembling the transversal beams Ueli Brauen + Doris Wälchli, Lausanne Conception de la structure et mentaire (entre 8 et 12 MPa). Le and longitudinal stiffeners was ingénierie/Structural design and comportement après fissuration carried out using stainless steel engineering est par contre relativement varia- plates fixed to the longitudinal Muttoni et Fernández, Ingénieurs Conseils SA, Ecublens (Lausanne) ble. Ceci est dû essentiellement à members prior to concreting (Fig. Eléments préfabriqués/ la distribution des fibres et à leur 4a and 4b). During erection, the Precast elements orientation peu homogène dues plates were bolted to the trans- MFP Préfabrication SA, Marin- Epagnier, et Dénériaz SA, Lausanne à la présence des armatures (bar- verse stiffeners (by means of nuts Fourniture de matériaux et assistance res de montage et tiges de fixa- screwed to bolts partly cast outside technique/Material supply and tech- tion) ainsi que des gaines des the concrete of the transverse nical assistance EIFFAGE TP – Département BSI®, câbles de précontrainte dans les beams, Fig. 3d). In the same way F-Neuilly sur Marne sommiers transversaux et des the transverse beams were sus- Construction métallique/ torons prétendus dans les raidis- pended from the longitudinal Steel elements and erection Stephan SA, Fribourg seurs longitudinaux. steel girders (Fig. 4c). Précontrainte/Prestressing Pour cette raison, les armatures The flexural strength of the trans- Freyssinet SA, Moudon passives et prétendues ont été verse beams is ensured by the

52 post-tensioning strands. Trans - reprendre les forces d’adhérence ces in the structural elements at verse and longitudinal bars were des torons prétendus et assurer la the expansion joints). The contri- also installed to ensure correct diffusion hors du plan des forces bution of fibres enhances (and placing of the duct. In addition to concentrées. La résistance élevée was considered) in the bond pro- this reinforcement, vertical bars à la compression a été indispensa- perties of concrete and to ensure were also arranged to fix or to ble afin d’assurer des épaisseurs the strength of the out-of-plane suspend the beams (Fig. 4a and b). réduites malgré l’introduction spreading of the concentrated The longitudinal stiffeners have d’effort concentrés importants forces. The very high compressive the same thickness (80–100 mm) (ancrage des câbles et joints ther- strength was required in order to but have a lower height (535 mm) miques, voir Fig. 4c). keep the dimensions very limited and their length varies between Afin d’empêcher le déversement despite the significant concen - 3.00 and 12.00 m. They were cast des sommiers minces, tous les trated forces (anchorage of ten- in the same way. The bending appuis sont disposés en dessous dons and thermic joints, see Fig. strength of the longest members des poutres longitudinales métal- 4c). was ensured by means of two liques (sommiers en BFUHP sus- In order to avoid lateral instabili- strands prestressed in the factory pendus) et les tiges de fixation ty of the thin and slender beams, before pouring the concrete. aux éléments longitudinaux (rai- all supports were arranged on disseurs et poutres métalliques) bottom of the longitudinal steel UHPFRC properties and ont été dimensionnées pour re- beams and the rods used to fix design criteria prendre les efforts de second them to the longitudinal ele- The ”béton spécial industriel” ordre qui pourraient en dériver. ments were designed accounting (BSI® with 200 kg/m3 metallic for the potential second order fibres, lf = 20 mm, øf = 0.3 mm) Conclusions effects. was used for all members with Une étude de variantes a permis UHPFRC. No thermal treatment de comparer la solution en BFUHP Conclusions was applied after concreting. The à deux options en bois lamellé- A detailed study of structural quality of the concrete was check- collé et en aluminium extrudé. solutions for the new roof of the ed by compression tests on D’autres options avaient été écar- Olympic Museum allowed a com- 100x100x100 mm cubic speci- tées dans une phase préliminaire parison between a solution in mens, by tension tests on drilled pour différentes raisons. Cette ultra-high performance fibre cores from one specimen (ø = 50 étude a démontré que le BFUHP reinforced concrete (UHPFRC) and mm, l = 200 mm) and 4-point- est un matériau intéressant pour others in timber and extruded bend ing tests on prisms (90 x 90 x la réalisation d’une toiture avec aluminium. The timber and alu- 400 mm) sawn from the same ele- des exigences accrues. En outre, le minium solutions were finally not ment. The tests exhibited a relati- BFUHP permet de réaliser des élé- selected for a number of reasons. vely low scatter with respect to ments durables malgré leurs fai- This study has shown UHPFRC to the concrete compressive strength bles dimensions et leur élance- be an interesting material for at 28 days (average value equal to ment. Cependant, il est encore à build ing roofs under demanding 188 MPa, standard deviation vérifier si le taux de fibres ne conditions. In addition, the equal to 9.8 MPa at 28 days) and pourrait pas être réduit en consi- UHPFRC allows producing durable the tensile strength of the cement dérant le fait que de toute façon, elements despite thin dimensions matrix (between 8 and 12 MPa). dans des éléments d’une certaine and high slenderness. Neverthe- The behaviour after cracking dimension, des armatures ordi- less, it is still to be checked if the how ever was more variable. This naires passives ou actives sont amount of fibres can be reduced is essentially due to the relatively indispensables pour reprendre les accounting for the fact that for inhomogeneous distribution and efforts plus importants. members with quite significant orientation of fibres because of dimensions, the placing of ordi- the presence of linking threaded nary or prestressed reinforcement rods, post-tensioning ducts (with is unavoidable to ensure suffi- their support bars during pour - Auteur/Author cient strength to withstand the ing) and pre-tensioning strands. Aurelio Muttoni internal forces. For this reason, the ordinary and Prof. Dr ès techn. ing. dipl. EPFZ Muttoni et Fernández, prestressed reinforcement have Ingénieurs Conseils SA been designed according to the CH-1024 Ecublens classical design methods so that aurelio,[email protected] they ensure resistance to all the tension forces at the ultimate state due to bending, shear and in-plane spreading of concentrat - ed forces (anchorage forces of post-tensioning tendons and for-

53 La salle de spectacle «Equilibre» à Fribourg The new ”Equilibre” theatre in Fribourg

Henri Brasey, François Prongué, Jean-François Klein

Introduction Introduction voisins tandis que sa forme en La nouvelle salle de spectacle de This new theatre in Fribourg, lo - pente est dictée par la présence Fribourg sise entre l’Avenue de la cated between the Avenue de la des gradins de l’auditoire de 700 Gare et le parc des Grand’Places Gare and the Grand’Places Park, is places. La hauteur dégagée sous constitue une prouesse techni- a real feat of engineering. The les dernières rangées permet que. On se rend compte des ca - theatre's features are best appre- l’aménagement d’un vaste foyer ractéristiques de la salle de spec- ciated by looking at its longitudi- d’entracte merveilleusement ou- tacle en considérant sa coupe lon- nal section. With a total length of vert sur le parc et offrant une vue gitudinale. D’une longueur totale 63.55 m, it is characterised by two imprenable sur les Alpes (Fig. 3). de 63,55 m, elle se caractérise par impressive overhanging parts (can- Le porte-à-faux côté ville repré- deux porte-à-faux impression- tilevers); the one on the town side sentant un poids de l’ordre de nants; celui côté ville mesure projects 15.50 m and is 21.50 m 13 500 kN et celui du côté parc un 15,50 m à une hauteur de 21,50 m above the esplanade, the one poids d’environ 25 000 kN, la au-dessus de l’esplanade, celui facing the Grand'Places Park pro- prouesse technique de l’ingénieur côté parc des Grand’Places mesu- jects 19.20 m and is between 7.0 m a été de mettre en équilibre ces re 19,20 m pour une hauteur va- and 9.0 m above the ground (Fig. deux efforts. Cela a été possible riant entre 7,0 m et 9,0 m (Fig. 1). 1). This view shows the logic and grâce à une collaboration étroite Cette coupe met en évidence la simplicity of the design. entre l’ingénieur et l’architecte logique et la simplicité du con- ainsi que à l’utilisation de la pré- cept. The building’s distinctive contrainte et celle de béton auto- features plaçant. La précontrainte est utili- Particularités de l’ouvrage The cantilever facing the town sée non seulement dans les sens Le porte-à-faux côté ville accueil- comprises two floors and houses longitudinal et transversal mais le en deux étages les bureaux de the offices for the theatre’s admi- également dans le sens vertical. l’administration du théâtre ainsi nistration staff and the rehearsal La longueur totale des câbles de que les salles de répétition. Il dé - rooms. It makes space for a large précontrainte est de l’ordre de gage une vaste place publique au public area at the foot of the 3230 m (Fig. 4 et 6). pied du bâtiment (Fig. 2). Du côté build ing (Fig. 2). The cantilever on Une autre particularité de cet parc la création du porte-à-faux the park side was necessary be- ouvrage réside dans l’utilisation est imposée par la présence d’un cause of an existing restaurant de béton auto-plaçant pour limi- restaurant existant et d’un passa- and road access to the neighbour - ter les nuisances lors des bétonna- ge routier d’accès aux immeubles ing buildings, whilst its sloping ges et plus particulièrement ga-

Fig. 1 Coupe longitudinale. Longitudinal section.

54 Fig. 2 Fig. 3 Le côté ville de la salle de spéctacle avec la place publique Le côté parc avec l’auditoire de 700 places surplombant le restaurant. à son pied. The park side with the 700-seat auditorium overhanging the restaurant. The side of the theatre facing the town with the public area in front.

shape is dictated by the tier rantir le confort des utilisateurs Seismic study system of the auditorium, which du cinéma multiplexe en sous-sol Because of its unusual shape, es- has a seating capacity of 700. The sur lequel se trouve partiellement pe cially the two cantilevers form- clear height underneath the last la salle de spectacle. ing a wide elevated structure built few rows makes space for a large on a narrow base, an exhaus tive interval foyer with a wonderfully Calcul sismique seismic study was carried out. The open aspect, overlooking the Compte tenu de sa géométrie purpose of this was to determine park and offering an unrestricted particulière et notamment de la the forces in the main load-bear- view of the Alps (Fig. 3). présence de ses deux porte-à-faux ing structures in this accidental The cantilever on the town side formant un large de corps de risk scenario using the so-called produces a force of approximate- bâtiment surélevé encastré sur response spectra method. The ly 13,500 kN, and that on the park une base de bâtiment étroite, un structure was modelled therefore side approximately 25,000 kN, calcul sismique poussé a été réali- in three dimensions (Fig. 5) in and the technical challenge sé. L’objectif était de déterminer order to first determine its eigen- facing the engineer was to balan- les efforts dans les éléments por- frequencies and, from these, to ce these two forces. This was teurs principaux sous cette situa- derive the internal forces and achieved by means of close colla- tion de risque accidentelle à l’aide moments that would be induced boration between the engineer de la méthode dite des spectres in the structure under the seismic and the architect and the use of de réponse. Le bâtiment a donc accelerations stipulated by the prestressing and self-placing con- été entièrement modélisé en trois standard. crete. Prestressing is used not only dimensions (Fig. 5), afin d’en dé - in the longitudinal and transverse terminer, dans un premier temps, Execution directions but also vertically. The ses fréquences propres de vibra- From a technical point of view, total length of the prestressing tion et d’en tirer, après applica tion the building poses several inter- cables is around 3,230 m (Fig. 4 des actions sur l’ouvrage et des esting challenges, since the canti- and 6). accélérations sismiques prévues lever housing the auditorium is Another particular feature of this par la norme, les efforts internes. located 8 m above the ground structure is the use of self-placing and measures more than 19 m in concrete to minimise disruption Exécution length. As it was not possible to during concreting and, even more Techniquement, la construction use temporary shoring during the importantly, to avoid inconveni- présente quelques défis intéres- construction phase, the construc- ence to the people using the mul- sants, le porte-à-faux supportant tion stages were stabilised using tiplex cinema in the basement, on l’auditoire situé à 8 m du sol, prestressing cables, which were top of which part of the theatre is mesure plus de 19 m de long. Un successively tensioned after cou- built. étayage provisoire pour la phase pling. These are arranged in the

55 Maître de l’ouvrage/Owner Ville de Fribourg, pour Coriolis Infrastructures Architecte/Architect Côté ville Côté parc Dürig AG, Zurich Ingénieurs/Engineers Groupement d’ingénieurs BT: Brasey Ingénieurs SA, Fribourg, et Fig. 4 T-Ingénierie SA, Genève Schéma de la précontrainte longitudinale et verticale. Entreprise/Contractor Implenia Construction SA, Fribourg Longitudinal and vertical prestressing layout.

de construction n’étant pas possi- two big concrete walls on either contrainte d’unités plus petites ble, c’est à l’aide des câbles de side of the seating tiers. The cho- soit 7 torons de 150 mm2 (7T15S/ 2 précontrainte mis en tension suc- sen unit is 13 x 150 mm strands P0 = 1367 kN) sont quant à eux

cessivement après couplage que (13T15S/P0 = 2,539 kN), whilst disposés dans les dalles constitu- les étapes de construction ont pu tension ing is carried out at the ants ainsi un élément travaillant à être stabilisées. Ces derniers sont free end (Fig. 7). la traction rectiligne disposé hori- disposés dans les deux grands On the town side, even though zontalement. murs-voiles béton disposés de part the cantilever is higher up (21 m La réalisation s’est fait en 2 étapes et d’autre des gradins. L’unité from the ground) it was possible principales: d’abord la cons truc - choisie est 13 torons de 150 mm2 to build in the conventional man- tion classique du corps central de

(13T15S/P0 = 2539 kN) et les mises ner, using falsework supported on 28,55 m de long puis la réalisation en tension se font à l’extrémité the esplanade (Fig. 8). The pre- par phases symétriques équili- dans le vide (Fig. 7). stressing cables of smaller units, brées des deux porte-à-faux côté 2 Du côté ville, bien que plus haute i.e. 7 x 150 mm strands (7T15S/P0 = ville et côté parc. Cette réalisation (21 m au-dessus du sol) la cons - 1,367 kN) are laid in the slabs, complexe a été faite en 9 phases truction s’est faite de manière tra- thereby creating a horizontal ele- pour le côté parc et 6 phases pour ditionnelle à l’aide d’un échafau- ment under tension. le côté ville. La méthode était celle dage prenant emprise sur l’espla- The construction process was di - de l’avancement avec couplage nade (Fig. 8). Les câbles de pré- vid ed into 2 main stages: first of des câbles avant chaque phase.

Fig. 5 Fig. 6 Modèle statique tridimensionnel et mode vibratoire Schéma de la précontrainte de la dalle du 6ème étage. global transversal sous accélération sismique. Prestressing layout for the 6th storey floor slab. Structural model and global transverse vibration modes under seismic acceleration.

56 Fig. 7 Fig. 8 Stabilisation des étapes de construction côté parc. Construction traditionnelle avec échafaudage. Supporting the construction steps on the park side. Conventional building with falsework.

all the conventional construction La numérisation et les simulations Auteurs/Authors of the 28.55 m long central body tridimensionnelles rendues possi- Henri Brasey and then construction of the two bles par le développement relati- ing. dipl. EPFZ Brasey Ingénieurs SA cantilevers on the town side and vement récent de nouvelles mé- CH-1701 Fribourg the park side in symmetrical and thodes et programmes de calcul [email protected] balanced phases. This complex ont permis de planifier avec toute François Prongué procedure was achieved in 9 steps la sécurité nécessaire les 15 pha- ing. dipl. EPFL Freyssinet SA in the case of the cantilever ses mentionnées ci-dessus. CH-1510 Moudon facing the park and 6 steps for Au point de vue historique, no - [email protected] the cantilever facing the town. tons que les études ont débuté en Jean-François Klein The method was to extend and octobre 2007 et que la réalisation Dr ès sc. techn., ing. dipl. EPFL T ingénierie SA couple the cables before each a duré de juin 2008 à juillet 2011. CH-1211 Genève new step. Cette durée de 3 ans, pour un [email protected] Thanks to digitisation and three- volume construit de l’ordre de dimensional modelling, made 39 000 m3, est le reflet de la com- possible by the relatively recent plexité de ce chantier en plein development of new calculation centre urbain de Fribourg. methods and computer software, it was possible to plan the 15 steps mentioned above with the requi- site degree of safety. As far as the sequence is concerned, the design studies started in October 2007 and construction lasted from June 2008 to July 2011. This three-year timescale to construct a volume of around 39,000 m3 reflects the complexity of this building site, situated right in the centre of Fribourg.

57 Manufacture Cartier Horlogerie à Couvet Cartier Horlogerie factory at Couvet

Philippe Menétrey, Jonathan Krebs

Introduction Introduction tifs et le restaurant. Les dimensions Cartier Horlogerie, branche du Cartier Horlogerie, a member of du bâtiment, définies par la surfa- groupe Richemont, est une des the Richemont group, is one of ce nécessaire à l’étage de produc- marques pionnières de l’horloge- the pioneering brands of modern tion, sont im portantes. La base du rie moderne dont les premières horology, the first watches of bâtiment est un rectangle de 80 montres datent de la fin du which date back to the end of the m de long par 70 m de large. Le XIXème siècle. Suite à la décision XIXth century. Following the deci- parti-pris architectural est d’atté- de Swatch de ne plus commercia- sion of Swatch not to sell its nuer la perception du rez-de- liser ses mouvements aux mar- movements to brands outside the chaussée en réalisant un bâtiment ques externes au groupe, Cartier group, Cartier Horlogerie has sur pilotis. Les espaces nécessitant Horlogerie a choisi de renforcer decided to strengthen its know- des murs sont ainsi regroupés son savoir-faire en matière de how of watch movements. Situat - dans la partie centrale du bâti- mouvements horlogers. Située à ed at Couvet, in the Val-de-Tra- ment tandis que les zones péri- Couvet, dans le Val-de-Travers, la vers, the new Cartier Horlogerie phériques, qui accueillent les par- nouvelle manufacture Cartier factory is devoted entirely to the kings, sont entièrement ouvertes. Horlogerie est entièrement dévo- manufacture of watch move- lue à la fabrication de mouvements and their assembly. Choix des matériaux et du ments horlogers et à leur assem- The building is designed in such a système structural blage. way that the whole of the pro- Généralités Le bâtiment est conçu de façon à duction can be located on one Hormis les enjeux inhérents au rassembler l’ensemble de la pro- floor. This area, free of all parti- développement du projet archi- duction sur un unique étage. Ce tions, is separated into two zones, tectural, plusieurs contraintes ont plateau, libre de toutes cloisons, one devoted to the machining of orienté la conception de la struc- est séparé en deux zones ; l’une parts of the movements and the ture ; la mauvaise qualité du sol dévolue à l’usinage des mouve- other to their assembly. The build - en place, la présence de radon, la ments, l’autre à leur assemblage. ing has three floors. The ground charge utile importante à l’étage Le bâtiment comporte trois éta- floor is designed for parking, de production, les délais de cons - ges. Le rez-de-chaussée est desti- cloakrooms, technical installations truction du gros-œuvre limités à né aux parkings, vestiaires, instal- and the reception area. The first sept mois et les objectifs finan- lations techniques ainsi qu’à la floor is the production floor and ciers du maître d’ouvrage en sont réception. Le premier étage est the attic contains the administra- les principales. l’étage de production et l’attique tive offices and the restaurant. Pour satisfaire au mieux à ces con- regroupe les espaces administra- The dimensions of the building, traintes, la structure porteuse est

Fig. 1 Photomontage de la manufacture. Photomontage of the manufacture. (© Richemont Intl. SA)

58 Fig. 2 Coupe longitudinale. Longitudinal section.

defined by the surface necessary différentiée par niveau comme vi- therefore decided to support the for the production floor, are sible sur la Figure 2. factory on a network of 215 piles large. The base of the building is inserted with vibratory pile divers a rectangle 80 m long by 70 m Pieux about 30 m long. As the conditi- wide. The architectural bias is to Le site, délimité par l’Areuse au ons of support varied throughout reduce the perception of the nord et le versant au sud, est the site, the piles have been ground floor by constructing a caractérisé par une couche d’envi- construct ed on the basis of a sett- building on piles. The spaces ron 30 m de dépôts lacustres et lement criterion similar for all the necessary for the walls are thus alluvions fluviatiles de consistan- piles (following the example of grouped in the central part of the ce molle. Une frange d’alluvions the driven piles), in order to make building while the peripheral peu compactes surplombe ces the construction of the piles more zones, where the parking spaces dépôts. uniform and to limit the risk of are located, are entirely open. L’ensemble du site est en consoli- differential settlement. The sett- dation lente. Il a donc été choisi lement criterion has been cali- Choice of materials and d’appuyer la manufacture sur un brated on the basis of PDA tests. the structural system réseau de 215 pieux à refoule- General ment d’environ 30 m de longueur. Foundation slab Apart from the issues inherent in Les conditions d’appui étant A general foundation slab is con- the development of the architec- variable sur le site, les pieux ont structed on top of the piles. It is tural project several constraints été réalisés sur la base d’un «cri- reinforced by longitudinal ribs in affected the design of the struc- tère de fonçage» similaire pour both directions. In order to con- ture. The poor quality of the tous les pieux (à l’instar des pieux trol the problems of sealing to ground, the presence of radon, battus), afin d’homogénéiser le avoid radon the foundation slab the high load-bearing capacity of niveau de travail des pieux et de of 25 cm is made of watertight the production floor, the time limiter le risque de tassement dif- concrete and its reinforcement is required to construct the building férentiel. Le «critère de fonçage» designed in such a way that it shell being limited to seven a été calibré sur la base d’essais meets the increased requirements months and the financial objecti- PDA. of cracking. In view of the large ves of the owner were the princi- dimensions of the foundation ple ones. Radier slab and in order to limit the num - To satisfy these constraints as far Un radier général est disposé au- ber of reinforcing bars, the slab as possible, the supporting struc- dessus des pieux. Il est renforcé has been made in separate steps ture has different functions on par des longrines dans les deux and then connected togeth er each level as shown on Figure 2. directions. Afin de régler les pro- after hardening of the concrete. blèmes d’étanchéité au radon, le Piles radier de 25 cm est réalisé en Production floor slab The site, bordered by the Areuse béton étanche et ses armatures The production floor slab rests on to the north and the side, is cha- sont dimensionnées de manière à columns spaced 14.40 m apart. racterised by a layer of about 30 m respecter les exigences accrues de The load-bearing capacity speci- of lacustrian deposits and alluvial fissuration. Etant donné les di - fied by the owner was 1 t/m2 in fluviates of soft consistency. A mensions importantes du radier order to allow plenty of flexibility fringe of alluvia that is not very et afin de limiter la quantité d’ar- in the production areas. The pro- compact overhangs these deposits. matures, ce denier à été réalisé en duction floor slab is therefore The whole site is in a state of étapes dissociées puis clavé après made of pre-stressed concrete as long-term consolidation. It was durcissement du béton. described further down.

59 Fig. 3 Montage de la charpente sur atelier. Assembly of the roof structure on the workshop.

Dalle de production La dalle de production repose sur des colonnes espacées de 14,40 m. La charge utile définie par le maî- tre d’ouvrage est 1 t/m2 afin de permettre une grande liberté d’aménagement dans les espaces de production. La dalle de production est donc en béton pré- contraint, comme décrit ci-après.

Dalle et toiture en structure mixte acier-béton La dalle sur atelier est une dalle mixte acier-béton permettant de franchir les grandes portées de 14,40 m. La dalle est constituée d’une charpente métallique dont les poutres principales sont de type HEB 600 disposées dans la trame des colonnes, comme illus- tré à la Figure 3. La charpente mé- tallique est recouverte d’une tôle Fig. 4 nervurée métallique. La dalle en Vue en plan et coupes de la précontrainte. béton a une épaisseur de 14 cm. View in plan and sections of the pre-stressing. La dalle toiture est également une dalle mixte acier-béton avec des poutres de type HEA 400. Les colonnes du niveau administra - tion/restaurant sont en acier. Leur section, rectangulaire, a été vo- lon tairement affinée de façon à les intégrer à la façade vitrée.

Cages d’escalier et d’ascenseur Les cages d’escalier et d’ascen- seurs sont en béton armé et font Fig. 5 office de noyaux de stabilisation Tracé et détails de la précontrainte dans le sommier et dans la dalle. permettant de s’affranchir de Trace and details of the pre-stressing in the beam and in the floor slab contreventements en façade.

60 Fig. 6 Coupe transversale d’un sommier précontraint. Fig. 7 Transverse section through a pre- Pose de la précontrainte. stressed lintel. Installing the pre-stressing.

Floor slab and roof in a composite Dalle de production providing the high load-bearing steel-concrete structure précontrainte capacity. The lintels enable the The floor slab on the workshop is La dalle de production, conçue efficiency of the pre-stressing to a composite steel-concrete floor pour porter bidirectionnellement, be increased and to simplify the slab permitting the large spans of est réalisée sur une trame de som- fitting of the cables while elimi- 14.40 m. The floor slab is formed miers orthogonaux alignés sur la nating the conflicts between the of a metallic roof structure the trame des colonnes, comme illus- cables of the beam and of the main girders of which are of the tré à la Figure 4. Cette conception floor slab. The floor slab has a HEB 600 type fitted in the frame- permet de franchir les grandes thickness of 50 cm and the beam work of the columns, as illustrat- portées tout en supportant la has a section of 90 cm wide and ed in Figure 3. The metallic roof charge utile élevée. Les sommiers 110 cm high, floor slab included, structure is covered by a ribbed permettent d’augmenter l’effica- which makes a very efficient metallic sheet. The concrete floor cité de la précontrainte et de sim- structure. slab has a thickness of 14 cm. plifier la mise en place des câbles The pre-stressing in the beam is The roof floor slab is also a com- en supprimant les conflits entre made up of two cables of seven posite steel-concrete floor slab les câbles des sommiers et de la strands of T15S steel alloy with type HEA 400 girders. The dalle. La dalle a une épaisseur de Y1860S7-15.7 following a parabo- columns of the offices/restaurant 50 cm et les sommiers ont une sec- lic trace as shown in Figures 4 and level are made of steel. Their rec- tion de 90 cm de large par 110 cm 5. This pre-stressing, with only tangular cross section has been de haut, dalle comprise, ce qui en two cables, enables 60% of the deliberately reduced so that they fait une structure très efficace. permanent loads to be balanced. can be in tegrated into the glazed La précontrainte des sommiers est The massive floor slab is equally façade. composée de deux câbles de sept pre-stressed in both directions. torons T15S de nuance d’acier The pre-stressing is made up of Stairwell and lift shaft Y1860S7-15.7 suivant un tracé T15S cables of four strands of the The stairwell and lift shafts are parabolique comme illustré aux steel alloy Y1860S7-15.7 installed made of reinforced concrete and Figures 4 et 5. Cette précontrain- in flat ducts every 1.8 m. The pre- act as a centre for stabilisation te, avec seulement deux câbles, stressing of the floor slab follows which means that diagonal braces permet de balancer 60 % des a trapezoidal trace to simplify its are not required. charges permanentes. introduction as shown in Figure 5. La dalle massive est également The production floor slab of Pre-stressed production précontrainte dans les deux sens. 5600 m2 was constructed in eight floor slab La précontrainte est composée de steps, each of about 700 m2, with - The production floor slab, design - câbles de quatre torons T15S de out any working joint. The longi- ed to carry loads bidirectionally, is nuance d’acier Y1860S7-15.7 ins tal- tudinal pre-stressing of the lintels built on a frame of orthogonal lés en gaines plates tous les 1,80 m. and the pre-stressing in the floor supporting beams aligned to the La précontrainte de la dalle suit slab is achieved with cables fitted frame of columns, as illustrated in un tracé trapézoïdal afin de sim- in the factory and the connec - Figure 4. This design enables the plifier sa mise en œuvre, comme tions to the concreting joints are big spans to be bridged while illustré à la Figure 5. made with couplers.

61 (a) (b)

Fig. 8 Vue a) du dessus et b) du dessous de la dalle de production. View a) of the upper side and b) of the underneath of the production floor slab.

La dalle de production de 5600 m2 The pre-stressing in the transverse duction, des portées avec une est réalisée en huit étapes, d’envi- beam is achieved with empty trame de 14,40 x 14,40 m, de la ron 700 m2 chacune, sans aucun ducts in which the pre-stressing charge utile de 1t/m2, des carac- joint de travail. La précontrainte cables are threaded in after con- téristiques géotechniques défavo- longitudinale des sommiers et la creting. This makes it possible to rables du site et de la durée de précontrainte en dalle sont réali- do away with couplers in the cen- construction limitée à sept mois. sés avec des câbles montés en tral zone, the thickness of which La structure porteuse a donc été usine et les raccords aux joints de is reduced to 30 cm in order to différenciée par niveaux pour bétonnage sont réalisés avec des increase the usable height in the satisfaire à ces exigences. Une coupleurs. technical rooms. dalle en béton précontraint sur La précontrainte des sommiers The use of bidirectional pre-stress- sommiers a été développée pour transversaux est réalisée avec des ing is justified by the stresses in la dalle de production, dont la gaines vides dans lesquelles les the structure at the ultimate limit charge utile est de 1t/m2. Cette câbles de précontraintes sont en- state. It also permits the behav- solution a montré toute son effi- filés après bétonnage. Ceci permet iour of the floor slab to be improv- cacité puis que la trame de 14,40 x de s’affranchir de coupleurs dans ed considerably in the service 14,40 m a été franchie avec des la zone centrale, dont l’épaisseur state and also to reduce substan- sommiers de 1,10 m de hauteur et est réduite à 30 cm afin d’aug- tially the quantity of passive rein- une dalle de 50 cm d’épaisseur. menter la hauteur utile dans les locaux techniques. Pour des raisons de durabilité, les niches ont été cachetées une fois Participants Intervenants les injections des gaines réalisées. Owner Maitre d’ouvrage L’utilisation de la précontrainte Cartier Horlogerie, Branch of Cartier Horlogerie, Branch of Richemont Intl. SA Richemont Intl. SA bidirectionnelle se justifie par les Architects Architectes sollicitations de la structure à A&A atelier d’architecture – A&A atelier d’architecture – l’état limite ultime. Elle permet Atelier A5 Atelier A5 Civil engineers Ingénieurs civils en outre d’améliorer considérable- INGPHI SA, INGPHI SA, ment le comportement de la dalle ingénieurs en ouvrages d’art ingénieurs en ouvrages d’art à l’état de service et également Piles Pieux Marti techniques de fondations SA Marti techniques de fondations SA de diminuer de manière substan- Reinforced concrete Béton armé tielle la quantité d’armatures pas- F. Piemontesi SA F. Piemontesi SA sives mises en place. Le taux d’ar- Pre-stressing Précontrainte Freyssinet SA Freyssinet SA mature moyen de la dalle de pro- Metallic roof structure and façades Charpente métallique et façades duction a ainsi pu être réduit à Progin SA – Berisha SA Progin SA – Berisha SA 110 kg/m3. The factory in figures La manufacture en chiffres Conclusion Reinforced concrete 6900 m3 Béton armé 6900 m3 Reinforcing steel 850 to Acier d'armature 850 to La construction de la manufactu- Pre-stressing steel 20 000 kg Précontrainte 20 000 kg re Cartier Horlogerie à Couvet Metallic roof structure 610 to Charpente métallique 610 to était soumise à des exigences par- Volume constructed 60 000 m3 Volume construit 60 000 m3 Cost of the structures CHF 10 600 000 Coût des structures ticulières au niveau de la surface, porteuses CHF 10 600 000 5600 m2 pour la surface de pro-

62 Fig. 9 Vue du bâtiment réalisé. View of the building constructed.

forcement installed. The average Les dalles des étages et de toiture with a composite steel-concrete amount of reinforcement of the ont été réalisées avec une structu- structure. This structure enables workshop floor slab could thus be re mixte acier-béton. Cette struc- the spans of 14.40 m to be cover- reduced to 110 kg/m3. ture permet de franchir les por- ed with sections of type HEB 600 tées de 14,40 m avec des profilés and a floor slab of 14 cm thick- Conclusion de type HEB 600 et une dalle de ness. The design of the Cartier Horlo- 14 cm d’épaisseur. These floor slabs also enable a gerie factory at Couvet was sub- Ces dalles permettent ainsi de surface area of 210 m2 to be jected to specific requirements re- couvrir des surfaces libres de tous covered thus offering great flexi- garding the surface area, 5600 m2 porteurs de 210 m2 offrant ainsi bility for the user. for the production area, spans with une très grande flexibilité pour Apart from its complexity, the a frame of 14.40 x 14.40 m, the l’utilisateur. project of the new factory for load-bearing capacity of 1t/m2, the De part sa complexité, le projet Cartier Horlogerie required the unfavourable geotechnical charac - de la nouvelle manufacture introduction of different load- teristics at the site and the dura- Cartier Horlogerie a nécessité la bearing structures for each floor, tion of the construction time that mise en œuvre de structures por- demonstrating the potential of had to be limited to seven months. teuses différentes pour chaque concrete structures very well. The supporting structure has the- étage, démontrant bien la puis- refore been designed differently sance des structures en béton. for each level to satisfy these re - quire ments. A ribbed floor slab made of pre-stressed concrete has been developed for the workshop Auteurs/Authors floor slab, where the carrying ca- Philippe Menétrey pa city can be up to 1t/m2. This so - Dr ès techn. ing. dipl. EPFL [email protected] lution has shown its efficiency since the frame of 14.40 x 14.40 m Jonathan Krebs has been covered with beams Ing. civil HES [email protected] 1.10 m high and a floor slab 50 cm thick. INGPHI SA The floor slabs of the floors and Ingénieurs en ouvrages d’art CH-1003 Lausanne of the roof have been constructed

63 Erweiterungsbau Kongresszentrum Davos Extension of the Davos Convention Centre

Joseph Schwartz

Einleitung Introduction drei Häusern und einem Hallen - Das Kongresszentrum Davos wur- The Davos Convention Centre was bad mithilfe der neu zu ergän- de von renommierten Architekten built by famous architects in four zenden Räume zu einem klaren in vier Bauetappen gebaut. Das separate stages. The first Conven - Gebäudekomplex zusammenzu- erste Kongresshaus wurde 1969 tion Hall was designed by Ernst führen und neu zum südwestli- von Ernst Gisel entworfen. Nach Gisel in 1969. After the first ex - chen Kurpark hin zu orientieren. einem ersten Ausbau 1979 wurde tension in 1979 it was developed Dies konnte nur gelingen, indem es 1989 zum Kongresszentrum ent - into a Convention Centre in 1989. die teils chaotische innere Er- wickelt. Mit der Erweiterung von With the extension of 2009/10 by schlies sung in ein übersichtliches 2009/10 durch den Basler Archi- the Basel architect Heinrich Degelo System umgewandelt wurde, das tek ten Heinrich Degelo ist das the Convention Centre is now lo - so in Erscheinung tritt, als sei es Kongresszentrum neu gegen den cated opposite the spa gardens von Anfang an so geplant gewe- Kurpark ausgerichtet und die ver- and the different parts of the sen (Fig. 1). schiedenen Häuser sind durch building are directly connected by Durch die Anordnung des Ein - eine repräsentative Wandelhalle a prestigious foyer. A statically gangs an die südliche Talstrasse direkt verbunden. Eine freischwe- freely suspended, spectacular ent stand eine grosszügige Er - bende, statisch spektakuläre Wa- honey comb ceiling covers the schliessung des Gesamtkomplexes bendecke überspannt den neuen new plenary hall. The striking zum bestehenden Kurpark hin Plenarsaal. Als Wahrzeichen für entrance portal was designed as (Fig. 2a), mit der einzigartigen den weltberühmten Kongressort the emblem for the world famous Sicht aus der Eingangshalle auf Davos wurde das markante Ein- Davos Convention Centre. die Davoser Bergwelt. Die sechs gangsportal konzipiert. neuen Säle im Innern ermögli- Architectonic design chen eine zusätzliche Öffnung Architektonisches Konzept The biggest challenge in the 2008 des Blicks auf die Schönheit der Die grösste Herausforderung beim competition to extend the Davos Landschaft. Das Prunkstück der 2008 durchgeführten Wettbewerb Convention Centre consisted in Anlage ist ohne Zweifel der neue zur Erweiterung des Kongress- bringing together the existing Plenarsaal für 1800 Teilnehmer, zentrums Davos bestand darin, labyrinths from three buildings dessen elegante, freischwebende das bestehende Labyrinth aus and an indoor swimming pool. Wabendecke aus Stahlbeton sich

Bestehendes Kongresshaus 1 Eingangsbereich 2 Alter Saal 3 Hallenbad 1

2/7 Erweiterung Kongresshaus 9 4 Haupteingang/Anlieferung 7 5 Plenarsaal (grosser Saal) 8 5/6 9 6 Grossraumbüro 3 8 7 Wandelhalle 7 9 8 Kleine Säle 9 Lichthöfe 4 N

Fig. 1 Schematische Situation (© Degelo Architekten). Schematic Situation (© Degelo Architekten).

64 (a) (b)

Fig. 2 Neuer Eingangsbereich des Kongresszentrums (a) und Wabendecke des Plenarsaals (b). New entrance area of the Convention Centre (a) and honeycomb ceiling of the plenary hall (b). © Ruedi Walti

This was done with the help of von der fünfeckigen Grundriss- load bearing components. For the the new halls and those to be form ableitet (Fig. 2b). Das Muster remainder only comparatively extended so that the complex aus überkreuzten Sechsecken ist small adjustments were necessary. forms a single building, which auch als «Cairo Pentagonal Tiling» In the foyer area some walls were faces the spa gardens to the bekannt, das bei den antiken replaced by floor beams . southwest. This could only be Mosaiken angewendet wurde. The extension building has a poly- done by changing the rather gonal floor plan of approx. 4350 m2 chaotic inner situation into a Allgemeine Beschreibung and contains a maximum of four coherent system that looks as if it der Interventionen storeys of different heights. In the had been planned like that from Das bestehende Kongresshaus area of the large halls with an the start (Fig. 1). wurde südostseitig durch den area of about 1350 m2 three sto- By arranging the entrance at the neuen Baukörper umschlossen. reys were combined to give a hall southern end facing Talstrasse a Im Bereich der Berührungs ebenen with a height of about 8.5 m. The large part of the total complex der Fassade zum Erweite rungs - rooms arranged adjacent to the looked onto the existing spa gar- bau mussten einzelne Fassaden- large hall and the platform can den (Fig. 2a), with a unique view bereiche abgebrochen und durch be used for various purposes. In from the entrance hall towards neue tragende Bauteile ersetzt the lowest floor on the Talstrasse the mountains around Davos. The werden. Am Bestand waren aus- side there are the technical six new halls inside provide addi- serdem nur vergleichsweise gerin- rooms, a side stage, a catering tional views of the beautiful ge Anpassungen erforderlich. Im room and cloakrooms. The re- countryside. The showpiece of Bereich des Wandelhallenumbaus main ing long area between the the complex is without doubt the wurden einzelne Wände durch swimming pool and Convention new plenary hall for 1800 partici- Unterzüge ersetzt. Hall was left unchanged by the pants. Its elegant, freely support- Der Erweiterungsbau hat eine building work. The space under ed, honeycomb ceiling made of polygonale Grundrissfläche von the floor slab of the large hall is reinforced concrete is derived ca. 4350 m2 und enthält maximal used for technical ducts. There is from a pentagonal shape (Fig. vier unterschiedlich hohe Ge schos - no conventional basement. 2b). The model for intersecting se. Im Bereich des grossen Saals Above the new building there are hexagons, each dividing into four mit einer Fläche von ca. 1350 m2 six small rooms in the spa garden pentagons, is also known as werden drei Geschosse zu einem storey. The rooms are separated ”Cairo Pentagonal Tiling”, which was used in antique mosaics. Bauherr Owner General description of the Landschaft Davos Gemeinde Landschaft Davos Gemeinde Architekt Architect work carried out Degelo Architekten, Basel Degelo Architekten, Basel The existing Convention Hall was Projektingenieur Project Engineer bordered on the south east side Dr. Schwartz Consulting AG, Zug, in Dr. Schwartz Consulting AG, Zug, in Zusammenarbeit mit DIAG Davoser conjunction with DIAG Davoser by the new building complex. In Ingenieure AG, Davos Ingenieure AG, Davos the area of the contact levels of Bauausführung Contractor the façade of the extension build- Toneatti AG, Bilten Toneatti AG, Bilten ing some façade areas had to be Fertigstellung Completion demolished and replaced by new November 2010 November 2010

65 chen Haupteingang durch eine breite Wandelhalle erschlossen. Im Bereich der alten abzubre- chenden Bühne greift die neue Wandelhalle in das bestehende Kongresshaus ein. Über dem grossen Saal befinden sich im Prome- nadengeschoss ein offenes Gross- raumbüro sowie ein Technikraum. Die geneigt verlaufende Vordach- konstruktion besteht aus zwei Platten, die durch dazwischenlie- gende Rippen verbunden sind. Generell gründet der gesamte Fig. 3 Erweiterungsbau auf einer Tief- Die Wabendecke im Bau. fundation mit bewehrten Bohr - The honeycomb ceiling during construction. pfählen aus Ortbeton mit einem Durchmesser von 90 bis 120 cm und Längen zwischen 7 und 9 m. ca. 8,5 m hohen Raum zusammen- by three internal courtyards. The Im Bereich der Erschliessung des gefasst. Die neben dem grossen small rooms are accessed from the grossen Saals auf der Nordseite Saal und dem Podium angeordne- southern entrance by a wide wurde eine kombinierte Pfahl- ten Räume weisen unterschiedli- foyer. In the area of the old stage Plattengründung ausgeführt. che Nutzungen auf. Im untersten to be demolished, the new foyer Talstrassengeschoss sind es Tech- is taking shape in the existing Besonderheiten des Trag - nikräume, eine Seitenbühne, ein Convention Hall. Above the large werks und konstruktive Cateringraum und Garderoben. hall there is a promenade floor Lösungen Die restliche längliche Fläche zwi- with an open plan office and a Die Tragstruktur ist in monoli- schen Hallenbad und Kongress - technical room. The inclined ca - thisch verbundener Stahlbeton- haus wird unverändert von der nopy roof design consists of two bauweise ausgebildet, wobei der Anlieferung belegt. Der Raum slabs, which are connected by ribs Grossteil der Decken im Verbund unter der Bodenplatte des gros- that lie between them. vorgespannt wurde. Die neuen sen Saals wird für Technikkanäle In general, the complete extension Gebäudeteile wurden zur Erzie- genutzt. Ein herkömmliches Unter - building is supported on a deep lung von Synergien betreffend geschoss ist nicht vorhanden. foundation incorporating rein - Erdbebenwiderstand fugenlos mit Über der Anlieferung befinden forc ed piles made of cast-in-situ jenen des Bestands verbunden. sich sechs kleine Säle im Kurpark- concrete with a diameter of 90 to Die Lastabtragung der Decke über geschoss. Die Säle sind durch drei 120 cm and lengths of between 7 dem grossen Plenarsaal erfolgt innenliegende Höfe unterteilt. and 9 m. In the area around the bei einer maximalen Spannweite Die kleinen Säle sind vom südli- lift and stairs to the big hall, on von 45 m über eine räumliche Tragwirkung. Beteiligt an dieser Tragwirkung sind einerseits die als plattenbalkenartiger Rost wirkende Wabendecke selbst, sowie Macalloy-Stab andererseits die Konsolwände in MSP Ø 40mm Kombination mit den Decken im Promenadengeschoss. Die eigentliche Wabendecken - kon struktion wurde auf einer Macalloy-Stab horizontalen Schalungsebene in MSP Ø 40mm weissem Ortbeton C30/37 hergestellt (Fig. 3). Eine besondere Her- ausforderung stellte die Umlen- kung der grossen Zugkräfte im un teren Bereich der zusammen- KNOTENPUNKTE laufenden Stege dar. Gewählt wurde eine Lösung mit 40 mm

1 m starken Macalloy-Stäben, die Fig. 4 schlaff eingelegt und jeweils an Umlenkung der Zugkräfte im unteren Stegbereich: Foto und Detailskizze. ihren Enden im Verbindungs- Deviating the tensile forces in the lower web area: photo and detailing. punkt einen kräftigen Vollstahl -

66 the north side, a combined pile- raft foundation was used.

Features of the structure and design solutions The structure consists of a mono- lithically connected reinforced concrete structure in which the majority of the floor slabs in the composite design are pre-stressed. The new parts of the building were connected without joints with those of the existing ones to Fig. 5 achieve synergies regarding earth- Zusätzliches, räumliches Tragsystem aus Konsolwänden quake resistance. und Wabendecke. The load transfer of the floor slab Additional 3D structural system of corbel walls and over the large plenary hall is honeycomb ceiling. achieved with a maximum span of 45 m exploiting a spatial structural system. Contributing to this dorn durchdringen, an dem sie ports, on which the honeycomb support are firstly the honeycomb mit Muttern verankert sind (Fig. ceiling is also suspended. The itself, acting as a slab-beam type 4). Um das duktile Verhalten des horizontal support forces of this of grid, and secondly the walls Zugsystems nachzuweisen, wur- corbel walls are transmitted to with corbels in combination with den 1:1-Versuche der Verbindung the roof slab. The resulting mem- the floor slabs in the promenade durchgeführt. Die Platte oberhalb brane forces converge in the slabs floor. der Wabenrippen wurde mit ver- due to the quasi axisymmetric The actual honeycomb construc - lorenen Schalungselementen aus arrangement of the corbel walls tion was manufactured on a hori- Stahlbeton hergestellt, die vor- in a force triangle in the ground zontal formwork in white cast-in- gängig mit den Lampenöffnun - plan. The membrane tensile for- situ C30/37 concrete (Fig. 3). A gen und weiteren technischen ces are completely absorbed by particular challenge was the de- Installationselementen versehen means of prestressed members, viation of the large tensile forces wurden. the majority of which follow the in the lower area of the converg- Die Flachdecke oberhalb des Pro- resulting force triangle between ing webs. The solution chosen menadengeschosses trägt die Ver- the corbel walls and are anchored involved 40 mm thick Macalloy tikallasten auf die Wabendecke in the area behind them (Fig. 6). rods, which are loosely laid and, ab. Zusätzlich zur Biegetragwir - Both strand systems that can take at their ends at the connection kung der Wabendecke wird ein tension forces of up to 3500 kN point, pass through a strong solid weiteres räumliches Tragsystem and wire systems that can take steel mandrel to which they are im Grossraumbüro des Promena - tension forces of up to 3700kN anchored with nuts (Fig. 4). Full- dengeschosses aktiviert (Fig. 5). were used as tendon cables. The scale tests on the joint were car- Die Unterkanten der drei konsol- corbel walls are also prestressed ried out in order to demonstrate artigen Wände aus Beton C30/37 with diagonally running tedons the ductile behaviour of the ten- bilden in den Saalgrundriss aus- that produce favourable deviation sile system. The slab above the kragende linienförmige Auflager, forces in the serviceability state honeycomb ribs was produced by an denen die Wabendecke zu sätz- (Fig. 7). Additional central pre- means of lost formwork made of lich aufgehängt ist. Die horizon- stressing is arranged in the slab reinforced concrete elements, talen Auflagerkräfte dieser Kon- over the promenade storey, in which had previously been fitted solwände werden in die Decken order to control or deviate the with lamp openings and further eingeleitet. Die resultierenden membrane compressive forces. technical installation elements. Membrankräfte schliessen sich The big canopy roof in the The flat slab above the promena- dabei in den Decken infolge der entrance area is designed as a 3D de storey carries the vertical loads quasi-axialsymmetrischen Anord- structural system, consisting of a acting on the honeycomb ceiling. nung der Konsolwände in einem lower and an upper reinforced In addition to the bending effects Kräftedreieck im Grundriss kurz. concrete slab as well as the inter- of the honeycomb ceiling a further Die Membranzugkräfte werden mediate connecting webs. To 3D system is activated in the open vollständig mit Vorspanngliedern ensure that the building met the plan office of the promenade sto- aufgenommen, die mehrheitlich physical requirements regarding rey (Fig. 5). The lower edges of dem entstehenden Kräftedreieck thermal insulation, most of the the three corbel walls made of zwischen den Konsolwänden fol- ca nopy webs were made of ther- C30/37 concrete in the hall plan gen und im Bereich hinter den mally insulating lightweight con- form cantilevering linear sup- Konsolwänden verankert sind crete LC12/13.

67 (Fig. 6). Als Spannkabel kamen Concluding remarks Das grosse Vordach im Eingangs- sowohl Litzensysteme mit Spann- The requirements placed on the bereich ist als räumliches Tragwerk kräften bis zu 3500 kN als auch design, the planning and the ausgebildet, bestehend aus einer Drahtsysteme mit Spannkräften development for the extension of unteren und einer oberen Stahl- bis zu 3700 kN zum Einsatz. Die the Davos Convention Centre betonplatte sowie den dazwi- Konsolwände sind ihrerseits eben - were considerably higher than for schenliegenden verbindenden falls mit diagonal verlaufenden a conventional building and Ste gen. Zur Gewährleistung der Spanngliedern vorgespannt, die reach ed the level of bridge con- bauphysikalischen Ansprüche be - für das Verhalten im Gebrauchs- struction. The excellent coopera- treffend Wärmedämmung wur- zustand günstig wirkende Umlenk- tion of all parties concerned in the den die an den Innenbereich an - kräfte erzeugen (Fig. 7). In der project – owner, architect, con - grenzenden Vordachstege weit- Decke über dem Promenadenge - sulting engineer, other technical gehend in Wärmedämm-Leicht - schoss ist eine zusätzliche zentri- planners, building site manager, beton LC 12/13 ausgeführt. sche Vorspannung angeordnet, contractor, concrete supplier and um die Membrandruckkräfte kon- post-tensioning company – en - Schlussbemerkungen trolliert zu führen bzw. umzulen- abled the building to be success- Die Anforderungen an den Ent - ken. fully completed. wurf, die Projektierung und die konstruktive Ausbildung waren beim Erweiterungsbau des Kon- gresszentrums Davos wesentlich höher als bei einem konventio- Kabeltyp A: Litzenspannsystem Typ 12-06 (Po = 2230 kN) nellen Hochbau und erreichten

Kabeltyp B: das Niveau eines Brücken bau - Litzenspannsystem Typ 19-06 (Po = 3531 kN) werks. Die hervorragende Zusam- menarbeit aller am Projekt Be- teiligter – Bauherr, Architekt, Bau- t I I ingenieur, weitere Fachpla ner, t ch si n A Ansich Bauleiter, Unternehmer, Beton -

I I AnsichA I n t si t cht i II n t II h c lieferant und Spannfirma – er- S

I I I t t i A n nsic möglichten die erfolgreiche Reali - h ht c AnsichII S Schnitt III t II sierung des Bauwerks.

Autor/Author Joseph Schwartz Prof. Dr. sc. techn., dipl. Bauing. ETH Dr. Schwartz Consulting AG

CH-6300 Zug I

t [email protected]

i s

10 m n

A Ansicht I Ansicht Fig. 6 Vorspannung zur Aufnahme der Membranzugkräfte. Prestressing to withstand the membrane tensile forces.

Ansicht I

Kabeltyp B Kabeltyp B

Kabeltyp D Kabeltyp D

Ansicht II Schnitt III Kabeltyp B: Litzenspannsystem Kabeltyp E Typ 19-06 (Po = 3531 kN)

Kabeltyp C: Kabeltyp D Drahtspannsystem C

C C C Typ 1000 (P = 990 kN)

o typ l typ typ typ l l l KabelTyp D: Kabe Kabe Kabe Kabe Drahtspannsystem Typ 1400 (Po = 1395 kN)

Kabeltyp E: Drahtspannsystem Typ 3700 (Po = 3689 kN)

10 m

Fig. 7 Anordnung der Vorspannung in den Konsolwänden. Arrangement of the prestressing system in the corbel walls.

68 Schulhaus Grono – Kraft und Form Grono School – Force and Form

Patrick Gartmann

Fig. 1 Ansicht des fertiggestellten Schulhauses Grono aus Osten (© Miguel Verme). View of the finished school at Grono from the east (© Miguel Verme).

Einleitung Introduction ben. Die Hanglage wird genutzt, In der Gemeinde Grono haben ein In the municipality of Grono an um Schule und Kindergarten ei - Architekt und ein Ingenieur ge - architect and an engineer have gene Zugänge und Aussen räume meinsam ein Schulhaus realisiert, collaborated to build a school zu ermöglichen: Jeweils durch das durch ein aussergewöhnliches with an unusual supporting fra- eine mittige, kreisrunde Öffnung Tragwerkskonzept seinen prä- mework of striking architectural der aussenliegenden Gebäude- gnanten architektonischen Aus - appearance. The structure was struktur betritt man auf der druck erhält. Das Bauwerk wurde honoured with the Architecture Hangseite über eine Brücke das mit dem «Architektur- und In- and Engineer prize for earthqua- Schulhaus und auf der Talseite genieurpreis erdbebensicheres ke-resistant buildings in Switzer- den ein Geschoss tieferliegenden Bauen 2012» der Schweiz ausge- land 2012. Kindergarten mit Hort. Im mittle- zeichnet. ren Stockwerk – dem Eingangs- Situation geschoss des Schulhauses – befin- Situation The village of Grono lies to the den sich Bibliothek, Saal und Das Dorf Grono liegt südlich des south of San Bernardino in the Lehrerzimmer, darüber liegen die San Bernardino im Misox, einem region of Misox, an Italian speak - Klassenzimmer. Im Untergeschoss italienischsprachigen Teil des Kan - ing part of the Grisons. The new befinden sich Werk- und Tech nik - tons Graubünden. Das neue Schul - school building is located below räume. haus liegt unterhalb der Haupt - the main street. The subdivision strasse. Das einfach gegliederte of the building’s volume is simple; Zusammenarbeit Ingenieur Volumen, quadratisch im Grund - its outline is a square facing all und Architekt riss und allseitig orientiert, ist von directions, surrounded by a circu- Das Ziel der intensiven Zusammen - einer kreisrunden Mauer umge- lar wall. The slope of the location arbeit zwischen Ingenieur und

69 20 m

Fig. 2 Fig. 3 Situation und Erdgeschoss (© Raphael Zuber). Die tragende Fassadenstruktur ergibt sich aus dem Situation and ground floor plan (© Raphael Zuber). Einschreiben von Ellipsen in die Wandscheiben. The load-bearing façade structure is achieved by the production of ellipses in the wall elements.

has been used to give both the Architekt sind effiziente und lisation of a harmonious load- school and the kindergarten their zugleich formal ansprechende bearing structure. All other ele- separate entrances and outside Strukturen. Die Flexibilität, die ments are subordinate to this spaces. Each entrance consists of a Gleichwertigkeit von Kindergar ten structure, which is made of co - central, circular opening in the und Schule sowie die Ökonomie lour ed cast-in-situ concrete. The exterior structure of the building. standen bei diesem Bauwerk intermediate walls, which are While the school can be accessed bereits beim Wettbewerbs ent - made of white-washed brick, as on the sloping side across a wurf im Vordergrund. Ingenieur well as the glazing and the build - bridge, the entrance to the kin- und Architekt entwickelten ge - ing services follow the given con- dergarden and nursery is located meinsam das Bauwerk mit den ditions pragmatically. Here, the one floor below on the valley geschwungenen Kragarm schei - engineer not only reacts to the side. The middle floor of the ben, die auch als übereck geführ- architectural design, but he influ- building – where the school’s te Bogenöffnungen gelesen wer- ences and shapes it in order to entrance is located – features a den können. Die Fassade ist die sharpen its appearance both aes- library, a hall and a staffroom. konsequente formale Umsetzung thetically and statically. The result - The classrooms are located on the eines in sich stimmigen Trag - ing structure has a strong visual top floor. The basement contains werks. Dieser Struktur aus einge- presence that combines architec- workshops and building services. färbtem Ortbeton sind alle ande- tural and engineering-related cri- ren Elemente untergeordnet. Die teria and demonstrates how the Cooperation between Zwischenwände aus geschlämm- two disciplines are mutually de - engineer and architect tem Backstein, die Verglasungen pendent. The strong shell can be The objective of the close coope- und die Haustechnik folgen dabei repeatedly adapted to meet the ration between engineer and pragmatisch den gegebenen Be - requirements of its users and is architect was the creation of both dingungen. Der Ingenieur rea- able to accommodate different efficient and aesthetically attrac- giert hier nicht nur auf den fashion trends and preferences tive structures. Flexibility in use, Architektenentwurf, sondern be- for the internal layout while re- the equivalence of kindergarten einflusst und prägt ihn, um maining open to changes in the and school, as well as economic sowohl formal wie statisch seinen building’s purpose. aspects were given priority alrea- Ausdruck zu schärfen. Dies ergibt dy at the competition design einen Bau mit hoher visueller Design of the load-bearing stage of the project. The engineer Präsenz, der die architektoni- structure and the architect co-developed schen wie ingenieurmässigen Kri - Material the building with its curved canti- terien miteinander verbindet und The complete load-bearing struc- levering walls, which can also be zeigt, wie sich die beiden Diszi - ture of the building uses concrete seen as arched openings stradd- plinen gegenseitig bedingen. Ein with a fire resistance of R 60. ling the corners. The shape of the starker Rohbau, der sich immer Concrete is extremely varied in its façade reflects the consistent rea- wieder seinen Nutzern anpassen appearance, and if it is employed

70 Hauptspannungen: Resultatkombination erdbeben Bauherrschaft/Client Comune politico di Grono Hauptspannungen: Resultatkombination kombiTS16Litzen Architekt/Architect Raphael Zuber, Chur Bauingenieur/Civil engineer Conzett Bronzini Gartmann AG, Chur Baumeister/Contractor Casada SA, Malvaglia

Preis/Prize Architektur- und Ingenieurpreis erdbebensicheres Bauen 2012/ Architect and Engineer prize for Fig. 4 earthquake-resistant buildings 2012 Auftretende Hauptspannungen in den Fassaden. Principal stresses in the façades.

kann, verschiedene Modeströ mun- consciously, it can highlight the das Fundament geleitet. Die gen und Vorlieben des Innenaus - architectural space and the struc- Kräfte der Fassade laufen zen- baus überlebt und auch spätere tural significance of the indivi- trisch auf jeder Seite zusammen Umnutzungen zulässt. dual parts of the building. At und werden somit an nur vier Grono School, concrete is used Stellen abgeführt. Dies ermög- Konzept des Tragwerks both as load-bearing and space- licht stützenlose Stockwerke, die Material shaping material. Moreover, by je nach Bedürfnis frei eingeteilt Die gesamte Tragkonstruktion adding coloured pigments, con- werden können, und spielt die des Bauwerks wird in Beton mit crete can be dyed quite easily. In Ecken der Geschosse frei. Die einem Brandwiderstand von R 60 the case of Grono school, 3.0% of Fassaden sind damit so angeord- erstellt. Beton ist in seiner Er- yellow and 0.6% of black iron net, dass Verkürzungen der De- scheinung äusserst vielfältig und oxide pigments in powder form cken aus Schwinden, Temperatur- kann über den differenzierten was added to the concrete mixtu- änderung und Vorspannung (elas - Einsatz die architektonisch-räum- re in order to adjust it to the tisch und Kriechen) nicht zu er heb - liche und die strukturell-kon- colour of the surrounding area. lichen Zwangsbean spru chun gen struktive Bedeutung des einzel- der Decken führen. Diese werden nen Gebäudeteils unterstützen. Structure als schlaff bewehrte Flachdecken Beton wird als tragendes und The compact, square outline of in einer Stärke von 36 cm ausge- raumbildendes Material einge- the building measures 25 by 25 führt. Die Spannweiten betragen setzt. Mit Farbpigmenten lässt metres. It ideally supports the fra- maximal 11 m. Vom Erdgeschoss sich der Beton zudem auf einfa- che Weise einfärben. Der Beton- mischung wurden 3,0% gelbe und Spannglieder 0,6% schwarze Eisenoxidpig mente in Pulverform zugemengt, um den gewünschten Farbton der Umgebung zu erhalten.

Struktur Die kompakte und quadratische Grund form von 25 x 25 m ist ideal für den Tragwerksentwurf dieses viergeschossigen Bauwerks, das Schnittkraft My (Stabachsen) [kNm] für: kombiTS, nur Zwängungen für eine spätere Aufstockung mit einem fünften Geschoss konzipiert wurde. Vertikale Beweh - rungsanschlüsse mit Kupplungen wurden dafür bereits eingebaut. -11044.64 Die Tragstruktur besteht aus ei nem Erschliessungskern, einer halb - 611.11 kreisförmigen Treppenwand sowie vier tragenden, vorgespannten Fig. 5 Fassaden. Die vertikalen Lasten Statisches Modell eines aus acht Kragarmen gebildeten werden direkt über den Er - Stockwerks. schliessungskern, die Treppen - Statical model (showing section forces) of storey formed wand sowie über die Fassaden in of eight cantilever elements.

71 mework design of the four-storey bis zum 2. Obergeschoss können Thanks to the use of load-bearing structure, which has been design - die Räume mit beliebigen, nicht- multi-storey frames as façades, ed so a fifth storey can be added tragenden Wänden aufgeteilt the building’s structural stability, at a later point. The necessary ver- werden. torsional stresses and secondary tical reinforcement connections Mit tragenden Stockwerkrahmen bending moments are well under with the corresponding couplings als Fassaden lassen sich die drei control: The wide-based façades have already been installed. The Zielsetzungen an die Stabilität, with their circular cut-outs provi- load-bearing structure itself con- die Torsionsverdrehung und die de significant horizontal resis- sists of a central access core, made Zwängungen lösen. Die breiter tance in x-direction and thus stif- up of a semi-circular staircase wall aufsitzenden Fassaden (mit den fen the structure against horizon- and four load-bearing, prestres- kreisförmigen Aussparungen) tal effects such as wind and earth- sed façades. Vertical loads are übernehmen dank ihres grossen quakes. Any effects in y-direction transmitted into the foundations horizontalen Widerstands die are absorbed by the staircase wall directly via the core, the staircase Aussteifung gegen horizontale and the central access core. This wall and the façades. The forces Einwirkungen, wie Wind und Erd - arrangement meets the following on the façade converge towards beben, in x-Richtung. In y-Rich - requirements: the centre on each side of the tung übernehmen dies die Trep - – It ensures the stability of the building and are thus transmitted penwand und der Erschliessungs - structure by employing at least in only four places. As a result, kern. Diese Anordnung erfüllt die three vertical wall elements. none of the floors requires any folgenden Anforderungen: – To avoid large torsional stres- columns and can thus be organis - – Für die Stabilität müssen min- ses due to wind (wind force ed freely according to the users’ destens drei vertikale Scheiben centre) and earthquakes (mass specific needs. At the same time, vorhanden sein. centre), a square outline is the corners of each storey are – Zur Vermeidung grosser Tor- ideal. The position and cross freed of any structural elements. sionsbeanspruchung aus Wind sections of the multi-storey This arrangement of the façades (Windkraftzentrum) und Erd- frames, the staircase segments ensures that contractions of the beben (Massenzentrum) ist die and the elevator core form the floor slabs due to shrinkage, tem- quadratische Grundrissform structure’s stiffness centre perature changes and pre-stres- ideal. Die Lage und Quer - (shear centre and centre of sing (elastic and creep) do not schnitte der Stockwerkrahmen, rotation). The centres of wind lead to significant stresses in the des Treppenwandsegments und force, mass and stiffness lie floor slabs. The floor slabs are des Liftkerns generieren das close together and thus ensure constructed as reinforced flat Steifigkeitszentrum (Schubmit- minimum loading of the fra - slabs with a thickness of 36 cm telpunkt und Drehzentrum). mes and low building torsion. and a maximum span of 11 m. All Für eine minimale Beanspru- The actual eccentricity in the x- floor areas from the ground floor chung der Rahmen und eine direction is ex = 0.17 m and in nd up to the 2 floor can be subdi - geringe Gebäudetorsion liegen the y-direction ey = 2.22 m. vided with any number of non- Windkraft-, Massen- und Stei- The structure was calculated as load-bearing walls. figkeitszentrum nahe beisam- non-ductile with q = 2.0. The faça- des taper elliptically to the outside into cantilevers and thus reprodu- ce the static forces of the concrete. The large vertical normal force

(Nk = –6600 kN) from permanent loads has a very positive effect on the reinforcement content of the façade at the level of embedment

of the basement (My = –9300 kNm). Due to the prestressing of the symmetrical cantilevers with 16 strands of 150 mm2 cross sectional

area (P0 = 3125 kN) each, the complete façade cross section is over- compressed. The design of the structure in the front elevation thus corresponds to the stresses.

Fig. 6 Bauaufnahme: Einige Wände des Erdgeschosses sind Design details geschalt und bewehrt. The moveable and fixed anchor- Picture of building: Some walls of the ground floor show ages for the prestressing require the formwork and the reinforcement. space. Therefore, the 40 cm

72 Fig. 7 Blick ins zentral angeordnete, halbkreisförmige Treppenhaus (© Miguel Verme). View of the centrally arranged semi-circular staircase (© Miguel Verme).

men. Die tatsächlichen Exzen- strong façade was linearly widen- benötigen Platz. Die 40 cm starke trizitäten betragen in x-Rich- ed in ground plan and in each of Fassade wurde im Grundriss je-

tung ex = 0,17 m und in y- the corners over a length of 4.90 m weils in den Ecken auf einer

Richtung ey = 2,22 m. from 40 cm to 90 cm on the in- Länge von 4,90 m linear von 40 cm Das Bauwerk wurde als nicht duk- side. In elevation, the ideal shape auf 90 cm nach innen verbreitert. til mit q = 2,0 gerechnet. Die Fas- of the cubic parabola was replac - In der Ansicht wurde die ideale saden verjüngen sich ellipsenför- ed by nearly congruent ellipses. Form der kubischen Parabel durch mig gegen aussen zu Kragarmen The necessary additional height Ellipsen ersetzt, die annähernd und zeichnen dadurch die stati- for the anchoring is produced by deckungsgleich sind. Durch das schen Kräfte des Betonbaus nach. displacing the vertex of the ellipse Verschieben des Scheitelpunkts Die grosse vertikale Normalkraft from the corner by almost 2.20 m der Ellipse vom Eck um knapp

(Nk = –6600 kN) aus ständigen towards the centre. 2,20 m zum Zentrum entstand nun Lasten wirkt sich beim Einbin de - The shape and geometry of the die benötigte Mehrhöhe für die horizont über dem Untergeschoss ellipse remains the same for all Verankerungen.

(My = –9300 kNm) sehr positiv auf storeys, although the heights of Die Form und Geometrie der den Bewehrungsgehalt der Fas- the storeys vary. The effect can be Ellipse bleibt für alle Geschosse sade aus. Durch die Vorspannung seen on each of the façade feet. immer dieselbe, obwohl die Ge - der symmetrischen Auskragungen From the design point of view, schosshöhen unterschiedlich sind. mit 16 Litzen à 150 mm2 Quer- the curved cantilevered walls can Die Auswirkung lässt sich am je- schnittfläche (P0 = 3125 kN) wird be imagined as curves that extend weiligen Fassadenfuss erkennen. der gesamte Fassadenquerschnitt around the corners at right Konstruktiv kann man sich die überdrückt. Die Gestaltung der angles. The classical keystone or geschwungenen Kragscheiben Kon struktion im Aufriss entspricht centre key known from traditio- auch als um 90° übereck geführte somit den Beanspru chun gen. nal arch designs is replaced by the Bogen vorstellen. Der klassische two prestressing cables crossing Schluss- oder Scheitelstein bei Konstruktive Einzelheiten at right angles, reproducing the Bogenkonstruktionen wird durch Die beweglichen und festen Ver - same static effect within the con- die beiden übereck gekreuzten ankerungen der Vorspannung crete. Vorspannkabel ersetzt. Die stati-

73 24.80 5 3.66 2.85

Grundriss Schnitt Ansicht

Fig. 8 Längsschnitt durch einen Fassadenbogen mit Vorspannung sowie Detail der Verschränkung der Vorspannung in der Fassadenecke. Longitudinal section through a curved façade element with prestressing as well as a detail of the crossing of the prestressing cable in the corner of the façades.

Another special feature of the sche Wirkung im Beton ist diesel- Autor/Author structure can be found in the be. Patrick Gartmann floor slabs which are running Eine andere Besonderheit sind die dipl. Bauing. FH SIA und dipl. Arch. FH SIA from the inside to the outside. von innen nach aussen durchlau- Conzett Bronzini Gartmann AG The monolithic connection of fenden Geschossdecken. Die mo- CH-7000 Chur façades and floor slabs makes nolithische Verbindung von [email protected] sense from a design point of view Fassaden und Deckenplatten ist and does not require any cantile- konstruktiv sinnvoll, benötigt ver plate joints. To still meet the keine Kragplattenverbindungen requirements as far as building und lässt sich bauphysikalisch mit physics are concerned, an edge Randdämmungen von 1,20 m insulation of 1.20 m width on the Breite an der Untersicht und voll- soffit and full surface insulation flächigen Dämmungen unter dem under the supporting floor are Unterlagsboden lösen. used. Bauausführung Construction work Die präzise Herstellung dieses The accurate construction of Schulhauses in Sichtbetonqualität Grono school in fair-faced concre- stellte eine Aufgabe dar, die in te represented a task which re- intensiver Zusammenarbeit von quired close cooperation bet- Planern und Ausführenden zu ween the design and execution lösen war. Die psychologischen teams. Psychological aspects in Aspekte in Bezug auf die Aus- relation to the contractors must führenden dürfen nicht vernach- not be neglected, for it is they lässigt werden, denn sie sind es, who convert the ideas of the de- die die Ideen der Planenden um - signers into an actual building. It setzen. Es ist naheliegend, dass is obvious that motivated teams mo tivierte «Sichtbeton-Bauteams» who specialise in fair-faced con- bessere und präzisere Arbeit lie- crete deliver better and more fern und so ihren Berufsstolz wie- accurate work and thus redisco- der entdecken. Die besten Bau- ver their professional pride. Also, teamerfahrungen werden zudem experience shows that the best erreicht, wenn jeder Ausführende results in a construction team are die Verantwortung für die fach- achieved if each participant ac - gerechte Umsetzung selber über- cepts responsibility for the techni- nimmt. cally correct implementation of his part.

74 Canopée en béton armé à la «Maison de l’Écriture» à Montricher Concrete Canopy of ”Maison de l’Ecriture” in Montricher

Aurelio Muttoni, Miguel Fernández Ruiz

Introduction Cet article présente une canopée en béton armé bâtie à la maison de l’Écriture à Montricher. Cette canopée est appuyée sur des colonnes préfabriquées en béton armé centrifugé avec des hauteurs allant jusqu’à 18 mètres. La auditorium forme de la canopée a été déter- minée sur la base du champ de library cisaillement d’un plancher dalle avec la même trame de colonnes. Les principes utilisés pour la conception et le dimensionnement de la canopée sont expliqués dans cet article, de même que les aspects principaux concernant les Fig. 1 technologies utilisées pour sa Vue de la canopée de la Maison de l’Écriture construction. Top view of the canopy of the MdE.

La Maison de l’Écriture et sa canopée Introduction hauteurs variant entre 9 et 18 mè- La Maison de l’Écriture (MdE) est An innovative concrete canopy tres. La canopée connecte les dif- un centre dédié à la promotion has been designed and construct - férentes parties de la MdE (Fig. 1) de la littérature. Le projet est ed for the Maison de l’Ecriture in et offre aux cabanes suspendues com posé de deux bâtiments (une Montricher. This canopy is suppor- des points pour leur accrochage bibliothèque et un auditoire) de ted by slender prefabricated (Fig. 2). même que de plusieurs cabanes columns up to 18 metres high and suspendues (actuellement en cons- was designed according to the Conception de la canopée truction). La canopée de la MdE shear field of an ideal flat slab. In Dans la forêt, une canopée n’est est l’un de ses symboles. Elle occu- this paper, the principles used for ni un ensemble de brins, ni une pe environ 4500 m2 et a une the shear field design are present- masse continue. De la même épaisseur de 400 mm. Elle s’ap- ed as well as the main aspects façon, la canopée de la Maison de puie sur des colonnes très élan- concerning the various technolo- l’Écriture n’est ni une grille de cées en béton centrifugé avec des gies used for its construction. poutres, ni une dalle plate, mais

Fig. 2 Photos de la canopée avec ses colonnes préfabriquées. Photos of the canopy of the MdE with its slender precast columns.

75 (a)y x (b)

In-plane In-plane shear force v y shear force v x z Cross-section shear force v v v y y x Cross-section shear force v x

dx = 1 dy = 1

(c) (d) In-plane principal shear force v0 φ v 0 x vy φ 0 In-plane Cross-section principal In-plane shear force v shear forces v y 0 shear forces v x

2 2 v0 = vx + vy v φ y tan ( 0 ) = vx

Fig. 3 Concept de champ de cisaillement et modèle sandwich: a) vue d’un élément; b) forces agissant dans le noyau; c) forces agissant dans les panneaux; et d) direction et intensité de l’effort tranchant principal. The concept of shear field. Sandwich model of a reinforced concrete slab element: a) general view of the element; b) forces acting on the core; c) forces acting on the panels; and d) magnitude and direction of the principal shear force.

The “Maison de l’Ecriture” quelque chose d’intermédiaire. Sa (where shear forces are larger) and its canopy forme transcrit la position idéale become continuous. However, at The “Maison de l’Ecriture” (MdE) des membrures qui devraient être a certain distance from the is a centre dedicated to literature, noyées à l’intérieur d’une dalle columns the shear forces are with the aim to preserve and to continue pour transmettre des moderate, resulting into linear promote it. It consists of two charges gravitaires sur les colon- members. build ings (a library and an audito- nes et les murs qui la supportent. rium), and a number of suspend - La position théorique des «brins» The concept of the shear field of ed residences (currently under de cette forme complexe a été a slab construction). The canopy of the déduite à partir d’un calcul numé- The shear field is a vector field ϕ MdE is one of its symbols. This rique, selon un modèle élastique representing the direction ( 0)

400 mm thick structure covering linéaire des champs de cisaille- and magnitude (v0) of the princi- 4,500 m2 is supported on slender ment: le béton marque l’espace pal shear force per unit length in centrifuged concrete columns qui définit les directions principa- a slab. With respect to reinforced with heights varying between 9 les de l’effort tranchant d’une concrete slabs, a sandwich model and 18 m. It links the different dalle qui couvrirait l’ensemble de is particularly useful to explain parts of the MdE (Fig. 1), and la Maison de l’Écriture. the physical meaning of such offers the anchorage points for parameters. It considers a slab di- suspending the residences (Fig. 2). Le concept du champ de cisaille- vided into three regions (Fig. 3a): ment d’une dalle a core carrying shear forces (Fig. Conceptual design Le champ de cisaillement est un 3b) and two outer panels (Fig. 3c) In a forest, a canopy is not an champ vectoriel qui représente la carrying in-plane shear and nor- ϕ assembly of branches, neither a direction ( 0) et l’intensité (v0) de mal forces (thus equilibrating continuum mass. In the same la direction principal de l’effort internal bending and torsional manner, the canopy of the MdE is tranchant unitaire d’une dalle. moments). With respect to the neither a flat slab nor an assem- Pour des dalles en béton armé, un core, the shear forces per unit bly of beams. Its shape expresses modèle sandwich est particulière- length acting in the cross-section the theoretical location and ment adapté afin d’expliquer la (vx and vy) are in equilibrium with shape where the shear forces are signification physique de ces the in-plane shear forces develop- transmitted inside a slab towards paramètres. Il considère la dalle ed in the upper and in the lower the supports (its shear field). Thus divisée en trois régions (Fig. 3a): faces of the core, see Figure 3b. the regions near the columns un noyau transmettant l’effort Such in-plane shear forces are in

76 (a) (b)

(c)

Fig. 4 Analyse du champ de cisaillement de la canopée: a) trame regulière; b) trame sans colonne entre la bibliothèque et l’auditoire; et c) détermination de la géométrie à partir du champ de cisaillement. Shear field analysis of the canopy: a) regular column spacing; b) one column eliminated between library and auditorium; and c) obtaining the canopy geometry.

tranchant et deux panneaux exté- turn in equilibrium with the colonnes et des bâtiments était rieurs (Fig. 3c), qui équilibrent la force-increments acting in the calculé. Cette analyse a permis torsion et les moments de flexion. panels as shown in Figure 3c. The d’adapter la forme de la canopée

Au sein du noyau, les deux com- in-plane shear forces (vx and vy) aux conditions de bord réels et de posantes de l’effort tranchant are two vectors whose resultant is raffiner sa forme pour l’adapter unitaire (vx et vy) sont en équilibre the principal shear force, defined aux besoins de l’architecture. avec les efforts rasants dévelop- by its magnitude (v0) and by its in- Après plusieurs essais, la forme de ϕ pés dans les panneaux supérieur plane direction ( 0), see Figure la Figure 4 était retenue comme et inférieur (Fig. 3b). 3d. satisfaisante des points de vue de Les composantes unitaires de l’ef- It can be noted that the in-plane l’architecture et du comporte- fort tranchant (vx et vy) sont ainsi principal shear force is in equili- ment statique. Une colonne entre les composantes de l’effort tran- brium with the cross-section prin- la bibliothèque et l’auditoire était chant unitaire agissant, qui peut cipal shear force in the core of the finalement enlevée afin d’amélio- également être défini par son sandwich, which has the same rer la qualité de l’espace dans ϕ intensité (v0) et sa direction ( 0), magnitude (v0) and develops in a cette zone. Comme la Figure 4b le voir Figure 3d. Une manière gra- plane perpendicular to the direc- montre, la géométrie du champ ϕ phique compacte de l’exprimer tion 0 (Fig. 3c,d). The shear field de cisaillement était alors adap- consiste à dessiner l’enveloppe can be represented by a set of tée à cette circonstance. Une fois ϕ des directions principales d’effort lines with direction 0 at each tranchant avec une épaisseur du point and whose thickness is pro- trait proportionnelle à son inten- portional to its magnitude (v0). sité. Un tel dessin s’avère très pra- Such plots help understanding Equipe/Team tique afin de comprendre le com- the shear forces developing in a Client/Owner portement statique de la structu- slab and thus how the forces are Fondation Jan Michalski, Montricher Entreprise totale/Total contractor re. transmitted to the supports of the Losinger-Marazzi SA, Bussigny slab. Architecture Recherche de la forme pour la Mangeat Wahlen, architects associés, Nyon canopée de la MdE Form-finding in the canopy of Conception de la structure et Afin de trouver la forme de la the MdE ingénierie/Structural design and canopée de la MdE, le champ de In order to determine the shape engineering Muttoni et Fernández, Ingénieurs cisaillement d’une dalle plate of the canopy of the MdE the Conseils SA, Ecublens (Lausanne) appuyée sur la même trame de shear field of a flat slab support-

77 ≈ ed on the existing buildings and que le champ de cisaillement était tely constant (Lcr /Ø 30). This columns was computed. This déterminé, seulement la matière optimized the mechanical beha- allow ed tailoring the canopy to nécessaire afin de transmettre viour of the members and was in the boundary conditions as well l’effort tranchant était retenue agreement with the architectural as refining its shape to adapt it to (voir Fig. 4c). Le champ des expression (refer to Fig. 2). To do the architectural needs. moments (moments de flexion et so, some columns required to be After a number of preliminary moment de torsion) de la structu- clamped in the foundations while designs, the shape of Figure 4a re était ainsi modifié par rapport others were simply supported on was selected as satisfactory from à celui d’une dalle plate (les nap- the foundations (to enhanc ed an engineering and architectural pes supérieures et inférieures du ease of construction of the prefa- point of view. A column between sandwich n’étant plus continues bricated members). the library and auditorium was partout). Cependant, le champ de eventually removed to enhance cisaillement de la dalle continue Detailed design the space in the place between et celui de la canopée restent Once the final geometry was esta- them (Figure 4b), and the result- identiques car les forces de la blished, the canopy was designed ing shear field thus adapted to canopée sont amenées jusqu’aux by using a 3-D model of the struc- this situation. supports suivant la direction des ture (accounting for the plane Once the shear field was selected, brins (ainsi justifiant la démarche and linear regions). This allowed only the required material for suivie pour trouver la forme de la determining the internal forces in carry ing shear was kept (refer to canopée). the structure, as its structural Fig. 4c). The moment field (bend - behaviour depends on the actual ing and torsion moments) of the Bâtiments placing of the members and on resulting structure was thus modi- Outre la canopée, deux bâtiments their linkage. On that basis, the fied with respect to that of the conventionnels ont été bâtis, une reinforcement was designed. continuous slab (as the top and bibliothèque et un auditoire. Les The reinforcement was adapted bottom layers of the sandwich bâtiments ont des murs de 12 to the various regions of the model are no longer present mètres de hauteur sur le niveau structure. For typical spans of everywhere). However, the shear du sol, ce qui imposait à la cano- approx. 7 m, concrete was rein- field of the continuous slab and pée de devenir une surface conti- forced by using ordinary reinfor- of the canopy is still the same, as nue à leur engagement. cement and steel fibres (20 kg/m3, the forces in the canopy are trans- Fig. 5a). The fibres allowed reduc - mitted to the supports by follow- Colonnes ing the required minimum rein- ing the direction of the beams Une canopée forestière est ap- forcement amount and helped in (thus justifying the selected pro- puyée sur des troncs élancés de la zones where ordinary reinforce- cedure to find the shape of the même façon que la canopée de la ment was difficult to place due to structure). MdE est appuyée sur des colonnes complex geometries. Non-pre- en béton élancées. Ces colonnes stressed strands were also used

Buildings ont une hauteur variable entre 9 (1/4” diameter, fp0.1k = 1,770 MPa) Besides the canopy, two conven- et 18 mètres et avec des diamè- to suitably reinforce the member tional buildings were introduced tres variant entre 450 et 350 mm. and to provide continuous rein- as part of the construction, a Les colonnes sont préfabriqués en forcement in the nodal regions. library and an auditorium. The béton centrifugé et ont un élan- In the linear members, reinforce- buildings have continuous walls cement mécanique à peu près ment followed the shape of the ≈ of 12 m height above the soil constant (Lcr /Ø 30). Ce dernier members and was composed of level. Thus, the canopy also tur- critère permettait d’optimiser le groups of up to 4 bars of diame- ned out to be a continuous slab at comportement statique tout en ter 10 mm bent “in situ”. In order their interface (Fig. 2). respectant l’expression architec- to resist shear, torsion and devia- turale de l’ensemble (Fig. 2). Pour tion forces, transverse pins were Columns ce but, certaines colonnes étaient arranged on the sides of the A forest canopy is supported by encastrées dans leur fondation members. This reinforcement was slender trunks in the same man- tandis que d’autres étaient sim- developed in the nodal (continu- ner as the canopy of the MdE is plement appuyées (afin de simpli- ous) regions, with a classical also supported on a number of fier la construction et la pose des orthogonal reinforcement layout slender columns. These columns éléments). (see Fig. 5a). have variable height varying bet- Steel heads were placed over the ween 18 and 9 meters and with Dimensionnement columns (Fig. 5b). These elements diameters varying between 450 Une fois la géométrie de la struc- were specifically designed to pro- and 350 mm. They were prefabri- ture définie, la canopée a été cal- vide sufficient punching shear cated in centrifuged concrete. culée à l’aide d’un modèle 3D de strength and anchorages requir - The mechanical slenderness of la structure (tenant compte des ed for suspending the residences. the columns was kept approxima- régions en forme de dalle et des The shear heads were composed

78 (a) (b) (c)

Fig. 5 Construction: a) armature ordinaire et torons non-précontraints; b) têtes métalliques; et c) gaînes de précontrainte. Construction: a) placing of ordinary reinforcement and non-prestressed strands; b) steel heads; and c) post-tensioning tendons.

brins). Sur la base de ce modèle, of four prismatic members with des cabanes. Ces éléments prisma- les efforts de réduction étaient threaded holes (for screwing the tiques permettaient en outre la déterminés et l’armature finale- anchorage pieces of the resi- soudure des profils latéraux et ment dimensionnée. L’armature a dences). These prismatic members des tôles de la tête (de 35 mm été adaptée aux différentes ré- also served to weld the lateral d’épaisseur). gions de la structure. Pour des profiles as well as the main plates Une zone particulière se trouve portées typiques de 7 mètres, le (35 mm thick). dans l’engagement entre la biblio - béton était renforcé avec des bar- A special zone was the region thèque et l’auditoire, où une co - res d’armature ainsi que 20 kg/m3 between the library and auditori- lonne avait été enlevée (Fig. 4b). de fibres (voir Fig. 5a). Les fibres um, where a column was remov- Dans cette zone, la portée corres- ont permis de réduire l’armature ed (Fig. 4b). In this zone, therefo- pond au double de la portée typi- minimale et ont aidé dans les re, the span length was thus dou- que et les flèches étaient très zones difficiles à armer. En outre, bled and deflections were signifi- importantes par rapport au reste des torons non-précontraints cantly larger than in the rest of de la canopée. En conséquence, étaient également disposés (1/4” the canopy. As a consequence, des câbles de post-tension furent de diamètre, fp0.1k = 1770 MPa) post-tensioning tendons were disposés (Fig. 5c) permettant de afin d’armer correctement l’élé- also placed (Fig. 5c), which allow - balancer une fraction adéquate ment et d’avoir une armature ed suitably balancing a considera- des charges permanentes et me- continue sur les zones nodales. ble fraction of the permanent nant ainsi à des flèches compara- Dans les brins, l’armature suivait loads leading to deflections simi- bles au reste de la structure. la forme des membres et était lar to those for the rest of the composée par des groupes de 4 structure. barres de diamètre 10 mm pliées sur place. Afin de résister à l’ef- Auteurs/Authors fort tranchant, la torsion et les Aurelio Muttoni forces de déviation, des épingles Prof. Dr ès techn. ing. dipl. EPFZ [email protected] transversales étaient disposées de chaque côté de l’élément. Cette Miguel Fernández Ruiz armature était ancrée dans les Dr ing. dipl. UPM [email protected] zones nodales (sur les colonnes) où l’armature était disposée sui- Muttoni et Fernández, vant une trame orthogonale clas- Ingénieurs Conseils SA CH-1024 Ecublens sique (Fig. 5a). Sur les colonnes, des têtes métal- liques étaient disposées (Fig. 5b). Ces éléments étaient conçus spé- cifiquement afin d’offrir une ré sistance suffisante au poinçonnement ainsi que pour permettre l’ancrage des cabanes suspendues. Les têtes métalliques avaient quatre profils prismatiques avec des trous filetés à l’intérieur permettant de visser les pièces d’ancrage

79 Construction d’une coque en béton armé à Chiasso Construction of an ellipsoidal concrete shell in Chiasso

Aurelio Muttoni, Franco Lurati, Miguel Fernández Ruiz

Introduction Introduction 51,8 m (axe court) × 22,5 m (hau- Cet article résume les propriétés This paper summarizes the main teur). L’ellipsoïde est sectionné principales ainsi que les méthodes properties and building techni- par un plan horizontal qui est utilisées pour la construction d’une ques used for the construction of constitué d’un socle en béton coque à forme ellipsoïdale en bé - an ellipsoidal concrete shell with composé de voiles verticaux trans- ton armé avec une portée maxi- a maximum span of 92.8 m and a versaux, avec une hauteur totale male de 92,8 m et avec une épais- general thickness of 10 cm. The de 18,24 m, voir Figure 1. Une seur type de 10 cm. La structure structure was cast both in sprayed description plus détaillée de la était bétonnée avec du béton concrete (for large slopes) and in géométrie et des raisons qui la projeté (dans les zones de pente ordinary concrete (for moderate justifient peut être consultée sous importante) et avec du béton or low slopes) and was reinforced [1]. coulé en place (pour les zones with conventional reinforcement, L’épaisseur de la coque était avec pente modérée ou faible). Le metallic fibres, post-tensioning variable. Une valeur de 100 mm renforcement de la coque est and shear studs depending on the était tenue par défaut, justifiée composé de barres d’armature location and internal forces of the par de raisons constructives (enro- conventionnelles, de même que shell. bage minimal) et afin d’écarter de fibres métalliques, de précon- les risques de voilement. Quatre trainte et de clous en acier selon Design nappes d’armature étaient dispo- les différents zones et les efforts Geometry and main properties sées, deux à l’intrados et deux à de réduction agissant. of the shell l’extrados de la coque. Les nappes The ellipsoid shell has axis dimen- d’armature étaient orientées sui- Conception et dimension- sions of 92.8 m (long axis) × 51.8 m vant les directions radiales (méri- nement (small axis) × 22.5 m (height). The diens) et tangentielles (parallèles) Géométrie et propriétés principa- ellipsoid is cut by a horizontal de l’ellipsoïde. Ceci était justifié les de la coque plane and is supported on a con- comme étant la disposition la plus Les dimensions de la coque ellip- crete basement composed of efficace pour des raisons stati- soïdale sont 92,8 m (axe long) × transverse walls, leading to a total ques. La disposition de quatre

(a)

(b)

Fig. 1 Dimensions principales: a) coupe selon l’axe longue; et b) coupe selon l’axe court. Main geometrical dimensions: a) section along long axis; b) section along small axis.

80 (a) (b)

Fig. 2 Construction de la coque: a) étayage; b) disposition de la précontrainte; c) projection du béton; et d) béton coulé sur place. Construction of the shell: a) temporary scaffolding; b) placing of prestressing tendons; c) spraying of concrete; and d) pouring of concrete.

height for the shell of 18.24 m, nappes d’armature permettait le structional reasons, to ensure see Figure 1. An extended des- contrôle des moments de flexion suitable crack control (which may cription on the geometry and its et des efforts tranchants se déve- potentially occur depending on reasons can be consulted else- loppant à la base de la coque the load cases) and to ensure suf- where [1]. (intersection avec le socle), dans la ficient safety against buckling of The thickness of the shell was zone précontrainte et pour con- the structure. variable. A value of 100 mm was necter les profils en acier d’une In addition to the ordinary rein- selected as the default thickness. pièce disposée dans l’ouverture forcement, 35 post-tensioning This was justified by constructio- zénithale de la coque (Fig. 1). tendons (0.6” monostrand tendon) nal reasons (minimum thickness Dans d’autres régions, les were arranged near the equator of necessary reinforcement cover) moments de flexion et les efforts of the shell (from level +5.50 m to and also to ensure sufficient tranchants étaient très modérés, level +12.60 m, see Fig. 1) to carry safety against buckling. Four rein- voir négligeables. Cependant, la membrane tension along the forcement layers were provided, disposition de quatre nappes horizontal direction (they pre sent - two at the intrados and two at d’armature était respectée pour ed in addition a limited dimension the extrados of the shell. The des raisons constructives, pour for the plastic duct thus minimiz- reinforcement layers were orient- assurer un comportement correct ing the disturbance in the com- ed in the radial (meridian) and vis-à-vis de la fissuration (pouvant pression field developing through tangential (parallel) directions. se développer pour certains cas the shell). The thickness of the This was selected as the most de charges) et pour écarter des shell was increased in this region effective layout for statical rea- risques de voilement. to 120 mm (between levels +4.24 sons. The arrangement of the En plus de l’armature convention- and +13.35 m). four layers was required to con- nelle, 35 torons de précontrainte At the level of the connection to trol bending moments and shear (mono-torons de 0,6” de diamè- the concrete basement (between forces developed at the basement tre) étaient disposés à proximité levels +4.24 and +5.14 m) shear connection, near the prestressed de l’équateur de la coque (depuis studs were also installed to provi- zone and for connecting to the le niveau +5,50 m jusqu’au niveau de sufficient shear strength and steel piece placed at the zenith +12,60 m, voir Fig. 1) afin de re- deformation capacity in this re- opening (Fig. 1). Bending moments prendre les efforts membranaires gion (subjected to parasitic shear and shear forces in other regions dans la direction horizontale. forces and bending moments). were quite small. Four reinforce- L’épaisseur de la coque était, pour The thickness of the shell was also ment layers were nevertheless des raisons constructives, augmen- 120 mm from level +21.60 m to arranged in all regions for con- tée dans cette zone à 120 mm the zenith opening. On the top

81 Fig. 3 Ouvrage fini. Completed work.

(entre les niveaux +4,24 m et part, the increased thickness allow - longueur de 30 mm et un rapport +13,35 m). ed the concrete shell to be con- longueur-sur-diamètre de fibre Au niveau de la connexion avec le nected to a steel structure placed de 80. Les fibres étaient disposées socle en béton (entre les niveaux at the zenith opening (10.21 m × afin d’améliorer le contrôle de la +4,24 m et +5,14 m), des clous 5.70 m), allowing daylight to fissuration (particulièrement dans (armature transversale avec têtes reach the inside of the mall. In la région précontrainte) et pour d’ancrage) étaient disposés afin addition, between levels +4.81 m améliorer la capacité de déforma- de garantir une résistance et ca- and +18.78 m a number of circu- tion du béton soumis à des efforts pacité de déformation suffisante lar openings (diameter 0.40 m) tranchants et des forces normales dans cette région (soumise à des were also arranged, see Figure 1. accrues (zone de liaison avec le moments de flexion et à des socle). Le béton projeté comportait efforts tranchant accrus). L’épais- Concrete properties 300 kg/m3 de ciment et 25 kg/m3 seur de la coque dans cette zone The structure was cast using spray- de chaux. Cette dernière était dis- était augmentée à 120 mm, tout ed concrete from level +4.24 m to posée afin d’améliorer la mise en comme depuis le niveau +21,60 m level +19.90 m. This allows using place du béton. Des tailles de gra- jusqu’à l’ouverture zénithale conventional (one-side) form- nulats entre 0 et 4 mm étaient (10,21 m × 5,70 m). Cette dernière work for the entire shell. Where utiliséss pour 70% de la structure, augmentation d’épaisseur permet the slope was sufficiently limited le reste étant entre 4 et 8 mm. de connecter une structure métal- (lower than 20°, from level +19.90 L’addition d’eau était effectué lique à travers laquelle la lumière to level +22.48 m) concrete was dans le pistolet de projection entre dans l’espace intérieur de la poured conventionally. For both (projection par voie sèche). coque. En outre, entre les niveaux concrete types a characteristic com -

+4,81 m et +18,78 m, des ouvertu- pressive strength (fck) at 28 days Construction de la coque res circulaires de 0,40 m de dia- equal to 30 MPa was specified. Le coffrage de la coque était dis- mètre étaient disposées, voir In the sprayed concrete region, posé sur des cintres et un étayage Figure 1. between level +4.24 m and level en bois, Figure 2a. Le coffrage +13.36 m, hooked metallic steel était composé de panneaux en Propriétés du béton fibres (30 kg/m3) were used. The bois pliés sur place et vissés (Fig. La structure était bétonnée avec du béton projeté depuis le niveau +4,24 m jusqu’au niveau +19,90 m. Ceci permettait d’utiliser du coffrage conventionnel (seulement d’un côté) pour toute la coque. Quand la pente était suffisam- Equipe/Team Références/References ment faible (moins de 20°, depuis Client/Owner [1] A. Muttoni, F. Lurati, M. Fer nán - dez Ruiz; Concrete shells – Towards le niveau +19,90 jusqu’au niveau Centro Ovale 1 SA, Chiasso Architecture efficient structures: Construction of +22,48 m), le béton était coulé or- Elio Ostinelli, Chiasso an ellipsoidal concrete shell in dinairement. Pour les deux types Conception de la structure et Switzerland, Structural Concrete, Ernst & Sohn, Germany, Vol. 14, No. de béton, la résistance caractéri- ingénierie/Structural design and engineering 1, pp. 43–50 stique à la compression (fck) à 28 Aurelio Muttoni, Franco Lurati, jours était spécifiée à 30 MPa. Miguel Fernández, Mendrisio et Dans la région du béton projeté, Lausanne Entreprise de construction/contractor entre les niveaux +4,24 m et Muttoni SA, Bellinzona +13,36 m, des fibres métalliques Coûts/Costs avec crochet (30 kg/m3) étaient CHF 5 300 000.– (TVA et honoraires utilisées. Ces fibres avaient une inclus/VAT and design costs inluded)

82 fibres had a length of 30 mm and 2b). L’armature était ensuite dis- ope ration ensured correct post- a length-to-diameter ratio of 80. posée et le béton était projeté ou tensioning transfer to the concre- The fibres were introduced to coulé sur place (Fig. 2c et 2d). Le te. Finally, the vertical struts of enhance crack control (in the temps requis pour disposer les the scaffolding supporting the post-tensioned region) and to armatures et pour bétonner la top region of the shell were gra- improve the ductility of concrete coque était d’environ 3 mois au dually released, leading to the under high normal and shear for- total. complete decentring of the struc- ces (at the connection to the Après le bétonnage, la coque ture. Measured deflections record- basement). The sprayed concrete était décintrée. Ceci est probable- ed during the process were in comprised 300 kg/m3 of cement ment l’opération la plus délicate good agreement with predicted and 25 kg/m3 of lean lime. The ayant mené plusieurs fois dans le values. Some pictures of the com- latter was to enhance the worka- passé à des effondrements totaux pleted work can be seen in Figure bility of the concrete. The aggre- ou partiels des coques. Dans le cas 3. gate sizes between 0 and 4 mm de la coque de Chiasso, une série The cost of the concrete structure were 70% of the total, the rest de phases étaient définies afin corresponded to 49% for the scaf- ranging between 4 and 8 mm. que le décintrage ne soit pas la folding and formwork, 21% for The addition of water was perfor- situation du projet déterminante. ordinary reinforcement, 5% for med at the spraying gun. D’abord, la moitié des câbles de post-tensioning, 24% for the post-tension était mis en tension spray ed concrete and 1% for the Construction of the shell (un sur deux). Ensuite, la partie poured in-situ concrete. This Formwork was placed against a du coffrage en contact avec la shows the relatively large cost of wood scaffolding, Figure 2a. The zone précontrainte était enlevée, scaffolding and formwork for formwork consisted of panels suivi par la mise en tension de la these types of structures, and bent in situ and fixed in their cor- totalité des câbles de post-tension. points to a fruitful future re- responding position (Fig. 2b). The Cette démarche permettait d’as- search topic to obtain more effi- reinforcement was then placed surer le transfert correct et effec- cient techniques. and concrete was sprayed or pou- tif des forces de précontrainte à red in situ (Fig. 2c and 2d). The la coque. Finalement, les étais time required for placing of the verticaux étaient graduellement reinforcement and concreting the descendus, menant au décintrage shell was about 3 months in total. complet de la coque. Les flèches After concreting, decentering of mesurées pendant ce procédé the shell was carried out. This is étaient en bon accord avec les Auteurs/Authors probably the most critical phase valeurs prédites. Quelques photos Aurelio Muttoni and has led in some cases to the de la structure finalisée peuvent Prof. Dr ès techn. ing. dipl. EPFZ Muttoni et Fernández, collapse of a shell structure. In the être observés dans la Figure 3. Ingénieurs Conseils SA present case the shell was con- Les coûts de l’ouvrage sont répar- CH-1024 Ecublens structed in a number of phases in tis à 49% pour le coffrage et aurelio,[email protected] order to avoid decentring to be l’étayage, 21% pour l’armature Franco Lurati the governing design situation. ordinaire, 5% pour la précon- Ing. dipl. EPFZ Lurati Muttoni Partner SA First, half of the post-tensioning trainte, 24% pour le béton proje- CH-6850 Mendrisio force was applied (one out of two té et 1% pour le béton coulé sur [email protected] tendons post-tensioned). Then, place. Ceci montre que les coûts Miguel Fernández Ruiz the wood scaffolding in contact associés au coffrage et à l’étayage Dr ing. dipl. UPM Muttoni et Fernández, with the post-tensioned zone was demeurent très importants et que Ingénieurs Conseils SA removed, followed by the post- des techniques plus efficaces sont CH-1024 Ecublens tensioning of all tendons. This encore à développer. [email protected]

83 Palestra doppia a Chiasso Double gymnasium in Chiasso

Andrea Pedrazzini, Eugenio Pedrazzini, Roberto Guidotti

Introduzione Introduction dalla falda la cui quota può supe- La costruzione in oggetto s’inse- The building in question is part of rare di quasi due metri la platea risce nel contesto del campus sco- the school and museum complex dello stabile. lastico e museale della città di of the city of Chiasso. The build - Di seguito saranno esposte le par- Chiasso. L’edificio si compone di ing consists of two elements: a ticolarità strutturali e di messa in due elementi: una copertura a sé separate square roof over the opera della copertura e dello zoc- stante con pianta quadrata corri- gymnasium and a partially buried colo. spondente alla sala ginnica e uno rectangular plinth-like base that zoccolo rettangolare parzialmen- connects with the school build - Considerazioni strutturali te interrato che si relaziona con ings and parking lot on the north La copertura gli edifici scolastici e il parcheggio side by means of a terrace and La sala ginnica è coperta median- presenti sul lato nord per mezzo the entrance, with the garden to te un solaio a cassettoni con 7 travi di una terrazza e l’entrata, con il the south by means of a wide precompresse di luce 32,85 m, giardino verso sud attraverso flight of steps, with the street and altezza 1,24 m (rapporto di snel- un’ampia gradinata,con il campo square to the east by means of a lezza L/H = 26,5) e spessore 35 cm stradale e la piazza verso est barrier and with the M.A.X Mu - in ciascuna direzione portante e mediante uno sbarramento e con seum and Workshop Space to the un solaio di spessore compreso tra il m.a.x Museo e lo Spazio Offi- west with a large fountain. i 16 e i 18 cm staccato termicamen- cina verso ovest con un’ampia The roof consists of a prestressed, te dalle pareti perimetrali. La pre- fontana. reinforced concrete lattice (grid compressione delle travi è calibra- La copertura è costituita da un form) suspended in space by four ta agli sforzi a flessione riscontrati solaio a cassettoni in calcestruzzo wall beams centrally supported by nel comportamento elastico della armato precompresso sospeso nel V-shaped elements (pillars) joined struttura (22 trecce da 150 mm2 vuoto mediante quattro travi pa- to the base at a single point. nelle tre travi centrali, 19 trecce reti appoggiate centralmente su The plinth supports the roof and nelle due travi seguenti e da 9 un cavalletto a V quindi congiun- deals with the special problems trecce nelle travi di bordo) ed è te al basamento in un solo punto. regarding waterproofing and up - disposta con andamento poligo- 1 3 Lo zoccolo funge da appoggio lift due to the groundwater table, nale con deviazioni a ⁄4 e ⁄4 della alla copertura e si confronta con i whose level can exceed the floor luce in modo tale da prevenire particolari problemi d’impermea- level of the building by almost l’intersezione dei cavi nei punti bilità e di galleggiamento imposti two metres. d’incrocio delle travi.

Fig. 1 Fig. 2 Pianta piano terra. Pianta livello –1. Ground floor plan. Level –1 plan.

84 395 226

Fig. 3 Sezioni. Sections.

Fig. 4 Andamento cavi graticcio. Lattice cable orientation.

Fig. 5 Andamento cavi travi parete. All beam cables orientation.

Below, we explain the structural Lungo il perimetro le travi del so - encountered in the elastic beha- and installation features of the laio appoggiano su 4 travi parete viour of the structure (22 strands roof and the plinth. di altezza 3,95 m e spessore 40 cm of 150 mm2 in the three central con una precompressione tale da beams, 19 strands in the next two Structural considerations prevenire la fessurazione del cal- beams and 9 strands in the outer The roof cestruzzo (2 cavi di 8 trecce da beams) and is arranged in a poly- 2 1 The gymnasium is covered by a 150 mm ciascuno). gonal layout with offsets at ⁄4 3 lattice ceiling with 7 prestressed Al centro ciascuna trave parete è and ⁄4 across the open space in beams with a span of 32.85 m, disposta su una forcella (pilastro a such a way as to prevent the inter - height of 1.24 m (slenderness forma di V) con struttura mista di section of the cables at the points ratio L/H = 26.5) and thickness of tubolari d’acciaio (ROR 273.25/ of intersection of the beams. 35 cm in each load-bearing direc- S355) e calcestruzzo capace di Along the perimeter, the roof tion, and a slab between 16 and accogliere le installazioni tecni- beams rest on 4 wall beams 3.95 m 18 cm thick, thermally insulated che e i pluviali. high and 40 cm thick with pre- from the perimeter walls. The Se considerate singolarmente le compression sufficient to prevent pre-compression of the beams is travi pareti risultano instabili ma the cracking of the concrete (2 ca- calibrated to the flexural stresses la loro unione determina una bles of 8 strands of 150 mm2 each).

85 trazione / tension compressione / compression

Fig. 6 Fig. 7 Funzionamento facciata. Funzionamento stabilità. Force transfer in the façade. Stability function.

struttura capace di resistere alle At the centre of each wall beam gio della copertura al terreno e la sollecitazioni orizzontali (vento e there is a fork (V-shaped pillar) resistenza alle sollecitazioni idro- sisma). Considerando una forza with a combined structure of steel statiche risultanti dalla falda la incidente su una facciata, le pare- tubes (ROR 273.25/S355) and con- cui quota massima si pone 1,80 m ti ortogonali allo sforzo impedi - crete that can accommodate tech- al di sopra della platea. scono la rotazione delle travi com - nical services and downspouts In un bilancio globale delle solle- planari allo stesso le quali tras- (drainpipes). citazioni verticali agenti ne risulta mettono la forza a terra median- Individually, the wall beams are che una platea con spessori stante una sollecitazione assiale delle unstable but together they form dard non è sufficiente a contra- forcelle. Una situazione analoga a structure able to withstand stare la spinta idrostatica agente la si riscontra anche nel caso di horizontal loads (wind and earth- e che il conseguimento dell’equi- una sollecitazione a torsione della quake). If one considers a force librio mobilita necessariamente struttura dove le singole facciate acting on one façade: the walls at anche il carico risultante dalla co - si sostengono reciprocamente. La right angles to the force prevent pertura. Da questa riflessione ne sovrapposizione di questi campi the rotation of its ground beams, consegue l’opportunità di una tensionali determina la stabilità which transmit the force to the distribuzione del carico della co - della struttura ad ogni genere di ground through axial stressing of pertura in platea il tutto a benefi- sollecitazione orizzontale. the V-shaped pillars. The same cio anche della tipologia della situation exists in the case of tor- fondazione disposta in superficie Lo zoccolo sional behaviour on the structure sul terreno alluvionale piuttosto Da un punto di vista statico lo where the single façades interact che su pali. zoccolo si confronta con la ridi - to provide mutual support. The La distribuzione delle forze d’ap- stribuzione delle forze d’appog- overlap of these tension fields poggio della copertura in platea è renders the structure stable under ottenuta mediante l’irrigidimen- any kind of horizontal load. to della stessa con due travi incro- ciate disposte sotto platea. Committente/Client The plinth Assieme alle pareti di bordo gli Cantone Ticino, Sezione della logistica/ From a static point of view, the architravi disposti sotto platea Canton Ticino, Logistics Department Architetti/Architects plinth handles the redistribution suddividono la stessa in quattro Nicola Baserga e Christian Mozzetti, of the forces supporting the roof porzioni quadrate di ca. 16,50 m Muralto to the ground and the resistance di lato. Ingegneri/Engineers Ingegneri Pedrazzini Guidotti Sagl, against the hydrostatic pressures L’esecuzione di contrafforti verti- Lugano resulting from the groundwater cali in continuità con la trave Impresa di costruzione/Contractor table whose maximum level is estendono lo stesso principio d’ir- Mafledil SA, Osogna 1.8 m above the floor level. rigidimento adottato per la pla-

In the global balance of vertical tea anche alle pareti est ed ovest Construction aspects stresses, a floor of standard thick- dello stabile. The roof ness is not sufficient to withstand The installation of the roof was the hydrostatic force and the load Aspetti costruttivi constrained by the particular aes- applied by the roof is also neces- La copertura thetic requirements of the wall sary to achieve equilibrium. This La messa in opera della copertura beams, which are made of fair consideration marks the suitabili- è stata vincolata dai particolari faced concrete without any ten- ty of distributing the roof load to requisiti estetici delle travi parete sioning niches for the prestressing the floor, bringing only benefits eseguite in calcestruzzo a faccia a cables. to this type of foundation, which vista senza alcuna nicchia di tesa- The latticed roof slab was cast is placed on the surface of the tura dei cavi precompressi. and prestressed before the peri- flood plain rather than being sup- La soletta di copertura a cassetto- meter façades. This procedure ported on piles. ni è stata gettata e precompressa required dimensioning the rib of The distribution of the forces sup- prima delle facciate perimetrali. the gridwork in such a way as to porting the roof on the floor is Questo modo di procedere ha support both the distributed achieved by stiffening it with two condizionato la centina del gra- weight of the concrete during the crossed beams under the floor. ticcio dimensionata in modo tale casting step and the concentrated Along with the outer walls, the da sostenere sia il peso distribuito load at the ends of the beams under-floor beams divide the del calcestruzzo durante la fase di after the tensioning of the pre- floor into four square areas of getto che il carico concentrato stressing cables. approx. 16.50 m on each side. risultante alle estremità delle Due to the limited capacity of the The creation of vertical buttresses travi dopo la tesatura dei cavi di concrete mixer at the construc- as a continuation of the beam precompressione. tion site, the casting of the lattice extends the same stiffening prin- A causa della capacità limitata roof (approx. 330 m3) was carried ciple adopted for the floor to the dell’impianto di betonaggio del out on two consecutive days: first east and west walls of the build- cantiere il getto della soletta a the 14 beams of the gridwork, ing. cassettoni di copertura (ca. 330 m3) followed by the roof slab.

87 Fig. 9 Fig. 10 Casseratura graticcio di copertura. Struttura grezza dopo il disarmo. Roof lattice formwork. Bare structure after removal of formwork.

è stato realizzato in due giorni The tensioning of the cables was Autori/Authors consecutivi: dapprima le 14 travi carried out in two steps: 30% 3 Andrea Pedrazzini del graticcio in seguito la soletta days after casting and the remain- Ing. civile dipl. ETHZ SIA OTIA di copertura. ing 70% after 21 days. Eugenio Pedrazzini La tesatura dei cavi é avvenuta in The perimeter wall beams were Ing. civile dipl. ETHZ SIA OTIA due fasi: 30% a 3 giorni dal getto cast in 4 stages, each in an L Roberto Guidotti e i restanti 70% dopo 21 giorni. shape, with casting interruptions Dr ing. civile dipl. EPFL SUP OTIA

Le travi pareti perimetrali sono in the middle area of the façade. Ingegneri Pedrazzini Guidotti Sagl state gettate in 4 tappe, ciascuna The prestressing cables, which are CH-6900 Lugano a forma di L, con interruzione di arranged in parallel with fixed and [email protected] getto nella zona mediana della moveable heads counterpoised at facciata. the corners, were tensioned in I cavi di precompressione, disposti three phases: 30% 3 days after parallelamente e con teste fisse e casting, 70% after 14 days and mobili contrapposte agli angoli, 100% approx. 28 days after cast- sono stati tesati in tre fasi: 30% a ing the last portion of the beam. 3 giorni dal getto, 70% dopo 14 The V-shaped pillars were pre- giorni e 100% dopo ca. 28 giorni fabricated at the construction site del getto dell’ultima porzione and positioned with a truck crane della trave. at the respective support points. Le forcelle sono state prefabbrica- te in cantiere e posate mediante The plinth autogru nei rispettivi punti di The floor and the perimeter walls appoggio. of the plinth of the building were conceived with the ”white tank” Lo zoccolo waterproofing system. Both in La platea e le pareti perimetrali the floor and in elevations, ele- dello zoccolo dell’edificio sono ments of controlled cracking were concepite con il sistema «vasca grouted several months after cast- bianca». Sia in platea che nelle ing in order to guarantee that the elevazioni sono stati predisposti underground structure re mains degli elementi di fessurazione waterproof. controllata iniettati qualche mese dopo i getti in modo tale da garantire l’impermeabilità della costruzione.

88 Abitazione sul lago di Sarnen House on Lake Sarnen

Mario Monotti

Introduzione Introduction l’impiego del calcestruzzo quale La costruzione è un edificio di pic- The structure is a small dwelling unico materiale da costruzione. cole dimensioni, ca. 100 m2 abita- with around 100 m2 of living space, L’analisi delle colonne ha eviden- bili, ubicato a Wilen sulle rive del located in Wilen on the shore of ziato come un’intersezione trop- lago di Sarnen nella Svizzera cen- Lake Sarnen in Central Switzer - po elevata da terra dei puntoni trale. L’abitazione è concepita per land. The house was designed to obliqui e una disposizione asim- approfittare in modo ottimale take full advantage of the beauti- metrica dei pilastri allontanasse le della bellezza del paesaggio visi- ful landscape, with uninterrupted traiettorie delle forze dalla strut- bile senza interruzioni dai quat- views from all four sides of the tura portante determinando delle tro lati. Organizzati su diversi structure. Organised on various sollecitazioni a flessione degli ele- livelli, gli spazi interni offrono tre le vels, the internal spaces offer menti portanti e, conseguente- diversi sguardi del lago: quello three different views of the lake: mente, un movimento rotatorio orizzontale sull’acqua dal sog- horizontally over the water from dell’intera copertura. Per miglio- giorno (quota 0.00), quello a pelo the living room (0.00 altitude), at rare il comportamento struttura- d’acqua dalla camera (quota –1.00) surface level from the bedroom le, i pilastri sono stati posti in asse e quello dall’alto dalla cucina (–1.00 altitude) and looking down con il tetto verso il lago e in corri- (quota +1.00). Contro terra, sotto on it from above in the kitchen spondenza del sostegno del tetto la cucina, con accesso dalla came- (+1.00 altitude). A bathroom and sopra la cucina verso monte. Nella ra, trovano spazio un servizio e il utility room are located under- configurazione scelta tre punti locale tecnico. Ai locali interni si ground beneath the kitchen, with d’appoggio della copertura risul- aggiunge un ampio spazio ester- access from the bedroom. In addi- tano fissi e l’origine del movimen- no coperto che si estende in tion to the internal rooms there is to della struttura è confinato in modo asimmetrico sui quattro lati a generous amount of covered un solo elemento portante, il dell’abitazione. Oltre alla particolare disposizione interna, la co - struzione ricava la propria valen- za dalle tensioni risultanti tra la Montagne struttura portante in calcestruzzo faccia a vista con singolare ric - Camera 20 Cucina 26 chezza geometrica e le sgarberie architettoniche che, rompendo le simmetrie e variando le quote degli spazi interni, rendono ancor più arduo l’esercizio estremo Soggiorno 43 della costruzione costretta a sor- reggere con soli due pilastri il carico dell’intera copertura. Di seguito sono esposte alcune Lago riflessioni strutturali e gli aspetti 01 5 costruttivi che hanno accompa- gnato la messa in opera dell’abitazione.

Riflessioni strutturali L’organizzazione degli spazi in - terni, la copertura con tetto a falde e la tipologia delle colonne portanti sono state assunte come parametri inderogabili. La pro- gettazione strutturale è stata focalizzata sulla disposizione dei Fig. 1 pilastri e sugli aspetti costruttivi Pianta e sezione sud/nord. della copertura presupponendo Plan and south/north section.

89 Thoughts about the structure The organisation of the internal spaces, the pitched roof and the type of load-bearing columns were taken as fundamental parameters. The structural design focused on the positioning of the pillars and the constructional aspects of the roof, presupposing Fig. 2 Modello statico. that concrete would be the only Static model. construction material. Analysis of the columns showed that an intersection of the diagonal struts too high above the ground and the asymmetrical outdoor space, which extends puntone obliquo sovrastante la location of the pillars would asymmetrically on all four sides of camera. La rotazione del tetto detach the flow of forces from the building. In addition to the indotta dalla deformazione del the load-bearing structure, lead unique internal design, the struc- pilastro al di sopra della camera è to bending stresses in the load- ture owes its appeal to the inter- stata controllata mediante la pre- bearing elements and a rotation play resulting from the load- compressione del braccio inclina- of the entire roof. To improve the bearing fair-faced concrete struc- to del pilastro e una forza ausilia- structural behaviour, the pillars ture, with a singular geometric ria di bilanciamento indotta atti- were placed in alignment with richness and startling architectu- vamente per mezzo di un tirante the roof facing the lake and in re, which by breaking up symme- posto in cucina nell’angolo della correspondence with the roof tries and varying the height of facciata. L’efficacia dei provvedi- support over the kitchen facing the internal spaces makes the menti intrapresi ha trovato ampio the mountain. In the chosen con- construction work even more dif- riscon tro con la deformazione figuration, three supports of the ficult, since the entire weight of verticale misurata lungo la faccia- roof are fixed and the source of the roof is supported by just two ta al termine della costruzione. structural movement is confined pillars. Più che sugli aspetti statici, la pro- to a single load-bearing element, Some information is given below gettazione della copertura si è the diagonal strut located above on the structure and the design focalizzata sulle problematiche the bedroom. The rotation of the aspects involved in erecting the costruttive determinate dal getto roof induced by the deformation building. del calcestruzzo su superfici ob - of the pillar above the bedroom is

Fig. 3 Cassero e armatura pilastri. Formwork and pillar reinforcement.

90 Fig. 4 Cassero e elementi prefabbricati copertura. Formwork and prefabricated roofing elements.

lique con pendenze fino all’80%. controlled by pre-stressing of the L’edificio è stato fondato su 16 In continuità con i pilastri, la inclined arm of the pillar and an pali battuti in ghisa duttile di struttura portante del tetto è auxiliary balancing force actively lunghezza compresa tra 10 e 15 m stata ridotta a singole aste inter- induced through a tie rod located e resistenza di 800 kN. La scelta di connesse rigidamente. La geome- in the kitchen in the corner of the una fondazione profonda è stata tria di questi elementi è stata rica- façade. The effectiveness of the determinata dalle caratteristiche vata mediante pannelli prefabbri- measures taken was clearly del terreno, dalla particolare vici- cati di calcestruzzo armato di demonstrated through the verti- nanza al lago e dalla concentra- spessore minimo (6 cm) rifiniti in cal deformation measured along zione dei carichi. modo tale da fungere da cassero the façade when construction Lo zoccolo dell’edificio (locale a perdere. Oltre a semplificare la was completed. tecnico e camera) è stato concepi- messa in opera gli elementi pre- More than on statical aspects, the to con il sistema «vasca bianca» fabbricati hanno contribuito in design of the roof focused on (iniezione dei giunti di lavoro) in modo sostanziale al contenimen- construction problems caused by calcestruzzo impermeabile faccia to delle imprecisioni esecutive the need to cast concrete on slant- a vista in modo tale da resistere permettendo al contempo di ri - ing surfaces with slopes of up to alla spinta del terreno e alle solle- durre il peso proprio della struttu- 80%. In continuity with the pil- citazioni idrostatiche relative a ra. Separata termicamente dal lars, the load-bearing structure of un’ immersione di 1,75 m. tetto, la gronda è stata gettata the roof was reduced to indivi- I pilastri presentano una sezione a sul posto quale elemento conclu- dual rigidly-connected rods. The quadrilatero concavo invariata (di sivo della costruzione. shape of these elements was ob- 0,29 m2 lato lago e 0,25 m2 lato tained using thin (6 cm) prefabri- monte) sul primo tratto e rastre- Aspetti costruttivi cated reinforced concrete panels, mata nei bracci (da 0,27 a 0,20 m2 Le diverse fasi del cantiere sono finished so as to serve as lost lato lago rispettivamente da 0,23 descritte brevemente corredate formwork. In addition to simplify- a 0,16m2 e da 0,25 a 0,18 m2 lato dalle cifre essenziali che carat- ing the work, the prefabricated monte). Il cassero dei pilastri è terizzano la costruzione. elements made a large contribu- stato concepito con due lati fissi e L’edificio è stato inserito nel pen- tion to limiting execution impre- due mobili in modo tale da favo- dio naturale mediante uno scavo cisions, while simultaneously rire la posa dell’armatura diseg- di 300 m3 con altezza 5 m e svilup- making it possible to reduce the nata in ogni singola posizione. po 15 m. Lo scavo è stato assicura- weight of the structure. Thermal - En trambi i pilastri sono stati messi to mediante calcestruzzo spruzza- ly separate from the roof, the in opera in una sola tappa me - to e 13 ancoraggi passivi di lung- eaves were cast on site, as the diante pompaggio di calcestruzzo hezza 8 m e resistenza 190 kN. final structural element. tipo SCC 30/37 dal piede. Il ramo più obliquo del pilastro lato Construction aspects monte è stato precompresso con The various construction stages 2 cavi di 4 trefoli cadauno aventi Committente/Owner are described briefly below, to- testa fissa al piede del pilastro e privato/private gether with the basic figures. mobile sul lato esterno della Architetto/Architect Christian Scheidegger, Zurigo The building was inserted in the copertura. Quale tirante di bilan- Ingegnere civile/Civil engineer natural slope with a 300 m3 exca- ciamento è stata impiegata una Monotti Ingegneri Consulenti SA, vation, height of 5 m and length barra Stafix M27. Locarno Impresa di costruzione/Contractor of 15 m. The excavation was rein- Le travi portanti della copertura, Melk Durrer AG, Kerns forced using cast concrete and 13 ottenute mediante la posa di ele- passive anchors with a length of menti prefabbricati su un telaio di

91 Fig. 5 Fig. 6 Vista sud (© Karin Gauch, Fabien Schwartz). Vista nord (© Karin Gauch, Fabien Schwartz). South view (© Karin Gauch, Fabien Schwartz). North view (© Karin Gauch, Fabien Schwartz).

8 m and a capacity of 190 kN. The legno, sono state gettate in opera the base of the pillar and move- building has a foundation of 16 in un’unica tappa con chiusura able on the external side of the ductile cast iron piles, with progressiva del cassero sul lato roof. A Stafix M27 bar was used lengths ranging from 10 to 15 m superiore. as a balancing tie rod. and a load capacity of 800 kN. La gronda è stata fissata al telaio The load-bearing beams of the The decision to opt for a deep della copertura mediante 12 pro- roof, obtained by placing prefa- foundation was determined by fili in acciaio con peso complessi- bricated elements on a timber the characteristics of the ground, vo di 2,1 t parzialmente rivestiti frame, were cast in a single ope- in particular the nearness to the con materiale isolante. Analoga - ration with progressive closing of lake and the concentration of the mente ai pilastri, la gronda è the formwork on the upper side. loads. stata messa in opera in una sola The eaves were attached to the The basement (utility room and tappa con calcestruzzo tipo SCC roof frame using 12 steel sections bedroom) was designed with a 30/37 pompato all’interno di un with a total weight of 2.1 t, par- ”white tank” system (injection of cassero ermetico. tial ly covered with insulating ma - working joints) in waterproof Complessivamente, per la costru- terial. Similarly to the pillars, the fair-faced concrete, so as to resist zione sono stati impiegati 135 m3 eaves were cast in a single opera- the earth pressures and the di calcestruzzo (55% nello zocco- tion using SCC 30/37 concrete, hydrostatic pressures associated lo, 2% nei pilastri, 24% nella pumped inside a hermetically- with a depth below the water copertura e 19% nella gronda) e sealed formwork. level of 1.75 m. 28 t d’armatura (40% nello zocco- In total, 135 m3 of concrete was The pillars have an unvarying con- lo, 5% nei pilastri, 36 % nella co- used in construction (55% for the cave quadrilateral section (0.29 m2 pertura e 19% nella gronda). plinth, 2% for the pillars, 24% for lake side, 0.25 m2 mountain side) the roof and 19% for the eaves), in the first part, which tapers in Conclusioni as well as 28 t of reinforcement the arms (from 0.27 to 0.20 m2 Malgrado le modeste dimensioni, (40% for the basement, 5% for lake side, from 0.23 to 0.16 m2 l’edificazione dell’abitazione sul the pillars, 36% for the roof and and from 0.25 to 0.18 m2 moun- lago di Sarnen ha richiesto ogni 19% for the eaves). tain side, respectively). The form- genere di lavoro specialistico del work for the pillars was designed genio civile. La riuscita dell’opera Conclusions with two fixed sides and two è stata conseguita grazie ad un Despite its modest size, the con- moveable sides, so as to facilitate grande impegno e un rapporto di struction of the house on Sarnen the casting of the reinforcement amicizia tra tutti gli addetti ai Lake required the use of every in each individual position. Both lavori. type of specialist civil engineering pillars were rendered operational work. The success of the work in a single casting, by pumping was achieved thanks to notable SCC 30/37 type concrete from the Autore/Author efforts and a friendly working base. The most oblique part of Mario Monotti relationship between all involved. the mountain-side pillar was pre- Prof. Dr. sc. techn., dipl. Bauing. ETH Monotti Ingegneri Consulenti SA stressed with 2 cables of 4 strands CH-6600 Locarno each, with the head attached to [email protected]

92 Elefantenpark «Kaeng Krachang» im Zoo Zürich – Betontragwerk Elephant House ”Kaeng Krachang” in the Zurich Zoo – Concrete structure

Fabian Persch

Einleitung Introduction hen zwischen den Auflagern er - Im Frühjahr 2014 wird der Elefan- In spring 2014 the elephant park geben sich aus architektonischen tenpark «Kaeng Krachang» als ”Kaeng Krachang” in the Zurich Vorgaben, wie den vorgesehen neue Attraktion des Zürcher Zoos Zoo will be opened as a new Besuchereinblicken, den Höhen für das Publikum geöffnet. Kern- attraction to the public. Centre - von Tordurchfahrten und der stück des 10 000 m2 grossen Gehe - piece of the 10,000 m2 large com- Grösse der Elefanten. ges ist eine kreisförmige Halle, die pound is a roundish concrete hall Als besonders komplex stellt sich von einer spektakulären Holzdach - roofed by an impressive curved der 270 m lange Ringbalken dar, konstruktion überspannt wird. wooden structure. The giant roof der der unregelmässigen Form Das riesige Dach mit einer Fläche with an area of 6,000 m2 and 85 m des Schalenrands folgt. Obwohl von 6000 m2 und einem Durch - in diameter acts as a self-support- er Spannweiten von bis zu 40m messer von 85 m wirkt dabei als ing shell-structure, whose loads zwischen den einzelnen Auflager - freitragendes Schalentragwerk, are transferred via a reinforced punkten zu überbrücken hat und dessen Lasten über einen Stahlbe- concrete ring beam to the local dabei die Durchbiegungen für die ton ringbalken in lokale Dachfun - roof foundations. The roof's geo- Fassadenplanung in einem engen dationen abgeleitet werden. Die metry was incrementally develop- Rahmen begrenzt bleiben müs- Geometrie des Dachs wurde mit- ed with the aid of an FE shell sen, soll er als filigranes, kaum hilfe eines FE-Schalenmodells in model. With an irregular appea- sichtbares Bauteil im Dachrand in - einem statischen Formfindungs- rance and a flowing shape its aim tegriert werden. Dieses Ziel lässt prozess schrittweise entwickelt. is to harmoniously fit into the sur- sich nur durch den Einbau von Mit seiner zufällig wirkenden rounding landscape. At the same Vor spannkabeln realisieren. Die geschwungenen Form soll es sich time, the curved edge is geared tatsächlich auftretenden Verfor- einerseits harmonisch in die Land - to the building's utilisation con- mun gen lassen sich bei diesem schaft einfügen, gleichzeitig ist cept. The rises of the arches bet- Prototypen im Vorfeld nicht exakt der gekrümmte Rand aber auch ween the supports are determin- definieren, sondern nur über dem Nutzungsprogramm des Ge- ed by architectural requirements, Sensitivitätsanalysen eingrenzen. bäudes angepasst. Die Bogenhö - such as the planned visitors’ views, Nicht nur planerisch, auch in der

Fig. 1 Künstlerischer Entwurf (Quelle: Markus Schietsch Architekten). Artist’s impression (source: Markus Schietsch Architekten).

93 Fig. 2 Nutzungskonzept Elefantenhaus (Quelle: Walt+Galmarini). Utilisation concept for Elefantenhaus (source: Walt+Galmarini).

clearance heights and size of ele- Ausführung stellt das Beton trag- Not only with regard to the de- phants. werk eine grosse Herausfor de - sign but also with the execution, A particularly complex compo- rung dar. So müssen grosse Teile the concrete structure presents a nent of the structure is the 270 m der Bewehrung und die Vor- major challenge. Due to the 3D long ring beam that follows the spannkabel aufgrund der dreidi- geometry of the structure, large uneven form of the roof edge. mensionalen Geometrie des Bau- sections of the reinforcement and While bridging spans of up to 40 m werks mithilfe von 3-D-Plandar - the post-tensioning tendons have with only very small deflections stellungen mit Koordinatenan ga - to be measured to millimetre permitted, the beam is meant to be millimetergenau eingemessen accuracy with the aid of 3D plans be thin and invisibly integrated in werden. with detailed information of the the roof. These requirements can coordinates. only be met by the use of post- Betontragwerk tensioning. Predictions of actual Die Anordnung des Tragwerks Concrete structure deflections of this prototype are ergibt sich aus den architektoni- The layout of the structure is difficult and can only be limited schen Vorgaben für die Nutzung given by the architectural requi- by means of sensitivity analyses. der Halle. Ziel bei der Tragwerks - rements for the utilisation of the

Fig. 4 Modell Dachfundation (Quelle: Fig. 3 Walt+Galmarini). Betontragwerk (Quelle: Walt+Galmarini). Model roof foundation (source: Concrete structure (source: Walt+Galmarini). Walt+Galmarini).

94 Fig. 5 Fig. 6 Bewehrung einer Dachfundation mit Holzdachkonstruktion mit Wandscheiben. Spannkabeln für die Wandscheiben. Timber roof construction with shear walls. Reinforcement of a roof foundation with bracing cables for the shear walls. planung war es, alle ohnehin be - building. The aim of the design BBRV 3700 sind jeweils mit Kör- nötigten Betonbauteile zur Ab- was to integrate all existing con- ben aus schraubbarer Bewehrung tragung der Dachlasten hinzuzu- crete members of the structure millimetergenau relativ zur Bo den- ziehen und so auf zusätzliche for the transfer of the roof load, platte der Fundation eingemes- Elemente möglichst zu verzichten. and thus avoid additional ele- sen. Das Betonieren der Wand- So dient beispielsweise die Aussen - ments as much as possible. Thus, scheiben erfolgt in mehreren ver- wand der Stallungen als li neares the exterior wall of the stables, tikalen Etappen. Die Wand köpfe Auflager für den Ring bal ken und for instance, serves as a linear werden zusammen mit dem Ring- die vorgesehenen Regen wasser- bearing for the ring beam, and balken betoniert. speicher sind als lokale Dach fun - the planned rainwater tanks are dationen ausgebildet und an den designed as local roof foundations Ringbalken unterirdisch verlaufenden Medien - and connected to the under- Um die planmässigen Beanspru - kanal angebunden. ground services duct. chun gen aufnehmen zu können sowie im aussergewöhnlichen Be - Lokale Dachfundationen mit vor- Local roof foundations with pre- messungszustand – wie beispiels- gespannten Wandscheiben stressed shear walls weise beim Ausfall von Felsan - Die Schalenkräfte werden vom The ring beam transfers the roof Ringbalken über vorgespannte loads to the roof foundations, Wandscheiben in die lokalen Dach- which are anchored by piles to fundationen abgetragen. Die ho - resist the vertical load compo- rizontale Komponente wird dabei nent, and by permanent rock durch permanente Felsanker, die anchors for the horizontal load vertikale Komponente über Pfäh- component. Projektdaten/Project data le in den Untergrund abgeleitet. It is essential for the roof's stabili- Bauherr/Owner Von zentraler Bedeutung für die ty that the shear walls only per- Zoo Zürich AG Gesamtleitung/General direction Formstabilität des Dachs ist, dass mit very small horizontal move- cga Consulting Group Aeberhard, die Wandscheiben nur geringe ments. Any deflection of the walls Dättlikon horizontale Verschiebungen er- results in a flattening of the roof Architekt/Architect Fischer Architekten AG, Zürich fahren. Jede hier auftretende Ver- shell. For this reason, each shear Landschaftsarchitekt/ formung hat ein Abflachen der wall is prestressed with a vertical Landscape architect Schale zur Folge. Daher ist jede post-tensioning tendon to the vetschpartner Landschaftsarchitekten AG, Zürich Wandscheibe für Beanspruchun - level of the live load. The fixed- Bauingenieur/Civil engineer gen auf Gebrauchslastniveau mit end anchorages of the wire cables Walt+Galmarini AG, Zürich, einem vertikalen Spannglied vor- BBRV 3700 together with the BlessHess AG, Luzern Ausführung/Contractors gespannt. Die festen Verankerun- cages with threaded reinforce- Landolt & Co. AG, Kleinandelfingen gen der Drahtkabel vom Typ ment are measured to millimetre

95 Fig. 7 Fig. 8 Spanngliedverlauf im Ringbalken (Quelle: Walt+Galmarini). Regelschnitt Ringbalken. Geometry of curved tendon in the ring beam (source: Walt+Galmarini). Standard section of ring beam.

accuracy relative to the bottom kern und damit der horizontalen in accidental design situations – slab of the foundation. The con- Stützung eines Widerlager be - such as the failure of rock-anchors creting of the shear walls is car- reichs – wie ein Zuggurt wirken and hence the horizontal support ried out in several vertical stages. zu können, ist der Ringbalken mit of an abutment zone – the ring The tops of the walls are cast at insgesamt neun Drahtspannglie - beam is prestressed with nine type the same time as the ring beam. dern vom Typ BBRV 1900 mit BBRV 1900 post-tensioning ten- Längen von 70 bis 120 m und dons with lengths of up to 120 m Ring beam einer Vorspannkraft von jeweils and a prestressing force of 190 t To withstand the design loads as 190 Tonnen vorgespannt. Die per tendon. The tendon layout is well as to act as a tension flange Spanngliedführung ist dabei drei- three-dimensional, i.e. the cables are arranged in such a way that, vertically, the ring beam lifts the roof in the spans, and, horizontally, is tied to the wall abutments. Two tendons are always arranged in parallel to avoid twisting of the ring beam. The position of the tendons and the prestressing niches had to be specified and measured on to millimetre accuracy. Since the tendons run over several concreting stages, the empty ducts were installed prior to concreting and the wire bund- les were eventually pulled in using a winch. Reinforcement and post-tensioning tendons were installed in a ”wooden channel” that was sub- sequently closed with the shutte- ring to a ”wooden pipe” and filled with self-compacting concrete. The lowest layer of the multi- layer wooden roof served as the soffit formwork and together with the upper formwork and the formwork sides was also left in the structure. Fig. 9 The casting of the ring was car- Verlegte Hüllrohre und Spannnische. ried out in 15 stages with a Placed sheath and prestressing niche. weight of up to 50 t of fresh con-

96 Fig. 10 Fig. 11 Einziehen der Drahtbündel in vorverlegte Hüllrohre. Befestigen der Konterschalung. Pulling in the bundle of wires in the previously placed Fixing the upper formwork. sheath.

dimensional, d.h. die Kabel sind crete. Due to its formula, the Nach dem mehrstufigen Anspan- derart angeordnet, dass sie in ver- installed concrete Holcim Selfpact nen der Kabel wurde das Dach, tikaler Richtung eine Dachanhe - 3716CL, despite of the low tem- das bis dahin von einem Lehrge - bung im Feldbereich und in hori- peratures, was able to achieve the rüst gestützt wurde, abgesenkt zontaler Richtung ein Zusam men- necessary strength for stressing und die Belastung auf den Ring - spannen mit den Wandscheiben after only three days. After stress - balken beziehungsweise die Dach - bewerkstelligen. Dabei sind je - ing the tendons, which was car- fundationen übertragen. Mithilfe weils zwei Kabel parallel ange- ried out in several steps, the roof von Fiberglassensoren werden die ordnet, um eine Verdrillung des that so far had been supported by Dehnungen überwacht und so Ringbalkens zu verhindern. Die falsework, was lowered, and the Rückschlüsse auf die tatsächlich Position der Spannkabel als auch loads were transferred to the ring vorhandenen Kräfte und Momen- der Verankerungsnischen musste beam and the roof foundations, te gezogen und mit den Berech - millimetergenau bestimmt und respectively. The deflections of nungsmodellen verglichen. eingemessen werden. Da die Vor- the structure are monitored with spannkabel über mehrere Beto- fibre-glass sensors such that con- nierabschnitte verlaufen, wurden clusions can be drawn as to the Autor/Author jeweils zuerst die leeren Hüll- actual forces or moments and Fabian Persch rohre verlegt und anschliessend comparisons with the results of dipl. Bauing. FH Stahlton AG die Drahtbündel mit einer Winde the calculation models can be CH-8340 Hinwil eingezogen. made. [email protected] Die Bewehrung und Vorspannung wurde in eine «Holzrinne» eingebaut, anschliessend mit einer Kon - terschalung zu einer «Holzröhre» geschlossen und mit selbstver - dichtendem Beton (SCC) ausge- füllt. Als Bodenschalung diente dabei die unterste Lage des Mehrschichtholzdachs, und auch die Konterschalung an der Ober- seite und die Randabschalungen verblieben anschliessend im Bau - werk. Das Betonieren des Rings erfolgte in 15 Etappen mit bis zu 50 Tonnen Frischbetongewicht. Aufgrund der Rezeptur erreichte der verwendete Beton vom Typ Holcim Selfpact 3716CL trotz der tiefen Aussentemperaturen bereits nach drei Tagen die zum Vorspannen benötigte Festigkeit.