THE ARUP JOURNAL I

I I ,I

SUMMER 1991 Front cover: Ponds Forge: steelwork detail (Photo: Jane Richardson) Back cover: Lobby perspective, Cerritos Arts Center. California (courtesy THEARUP of the architects) JOURNAL Vol.26 No.2 Editor: Summer 1991 David J . Brown Art Editor: Desmond Wyeth FCSD Published by Deputy Editor: Ove Arup Partnership Caroline Lucas 13 Fitzroy Street, Editorial Assistant: London W1 P 680 Gabrielle Scott 3 Ponds Forge This centre forms the focal point of the 1991 World Student International Sports Centre Games in Sheffield, and comprises a main pool hall. including Mike Brown, Martin Butterworth, Olympic-standard swimming and diving facilities, a leisure Paul Kay, Paul Stevenson complex, and a multi-purpose sports hall.

10 New Guesten Hall A new brick building at the Avoncroft Museum of Buildings in Gary Marshall Bromsgrove was constructed to support and display the 14th century Guesten Hall timber roof from Worcester.

11 Hong Kong Park Aviary A 5000m2, stainless steel wire mesh, slung from three slender Ian Robinson, Brian Forster arches, provides an enclosed habitat within a natural valley for 150 species of South East Asian birds.

14 Weatherstone Riding Rink A timber and steel roof structure was designed to allow an Guy Nordenson, Liam O'Hanlon uninterrupted span over a private riding ring on a country estate in Connecticut.

17 Cerritos Arts Center, This multi-purpose facility will include an auditorium of unparalleled Callfornla flexibility, able to house concerts. opera, musicals. and drama, as Chris Jofeh well as public and community events like banquets and trade shows.

22 Design for hazard: Fire The fourth article in this Arup Journal series looks at the role of Chris Barber, Paula Seever, fire engineering in the context of transport terminal buildings and Andrew Gardiner offshore structures.

2 Ponds Forge International Sports Centre

Architect: FaulknerBrowns • Mike Brown, Martin Butterworth, Paul Kay, Paul Stevenson

Introduction Later it was decided that it should also incor­ which forms the focal point of the corner site The city of Sheffield (population 560 OOO) is a porate an international diving pool. The design overlooking Park Square. The Rotunda is the former industrial empire built on quality steel. In had to comply fully with the rules set down by meeting place and distributor to the other the late 1970s and '80s this industry collapsed FINA (Federation intemationale de natation facilities, and can also be used for exhibitions and, apart from the massive unemployment this amateur), to provide the first international swim­ and displays. At the lower level are inter­ created, the lower Don Valley was left as a ming and diving complex to be built in Britain connecting changing rooms leading to the main corridor of closed steelworks stretching out from for 20 years. competition pool hall. the leisure pool and the the city centre. In an effort to revive the fortunes The building is located on a prominent city multi-purpose sports hall. The design concept of the city and as part of its regeneration. the centre site. Ponds Forge - acknowledged as of what are effectively three buildings provides City Council decided to apply to host the XVlth the gateway to Sheffield - which had been an ideal location for movement joints and sub­ U niversiade 1991 . the World Student Games. occupied by industrial premises for almost sequently assisted with packaging the works One of the aims of these events is that the host 200 years. A new linear park will be created to into manageable contracts. city be encouraged to build new facilities, and extend from the railway station across the land­ The site so give long-term benefit to itself and its scaped roundabout at Park Square and then Its principal former use was the manufacture of community. through to Cutlers Wharf. The River Sheaf is iron and steel using two natural resources close The new Ponds Forge International Sports visible in places. but culverted under Ponds to the site - water from the River Sheaf and coal Centre is one of several facilities Sheffield is Forge. Within the tight confines of the site, the from a 2m thick seam at a depth of around 25m. providing for the Games. It has been designed design attempts to explore and articulate the The site was overlain by fill of varying composi­ as a focal point for a variety of events - swim­ complex relationships between international tion which included industrial contaminants. ming, diving, water polo and volley-ball. Else­ sports competition , leisure pursuits and tourist foundations of previous buildings and remnants where. other buildings include an outdoor multi­ attractions, whilst relating it all to the needs of of the industrial past. The infilled Ponds Dam purpose stadium, an indoor multi-purpose the city community. In the long term it is in­ occupied a significant area, fed by a number of arena and a water polo/leisure complex. Exist­ tended that a light rail system known as 'Super­ water courses. The sloping rockhead varied ing buildings, such as the Lyceum Theatre (see tram ' will complete the public transport facilities between 4m and 7m in depth and mine work­ The Arup Journal, Spring 1991), are being to the building, running along the frontage of ings were known to exist. restored to house a cultural festival , and the Commercial Street. The first site activity was to establish the extent 1960s Hyde Park flats refurbished to accom­ Ponds Forge consists of three interlocking of these workings, their depth and their ability modate the 4000 competitors. volumes of opposing curved roof forms above to sustain the load from the buildings. The condi­ Competition, brief, and concept and below a public terrace, which links several tion of the overlain sandstone and mudstone In November 1987, FaulknerBrowns* were in­ pedestrian routes to and across the site. These and depth of the workings necessitated vited to take part in a limited competition for the volumes become a backdrop for the circular grouting of the abandoned mining seams over design of the new sports and leisure complex. portico of the entrance, known as the Rotunda, a considerable area.

1. Sheffield city centre w,th Ponds Forge International Sports Centre 1n foreground

3. Pool hall elevation. 4. Central core elevation. Y-1-~""<.-.._ River SheaJ ~n culvert Sheaf S1ree1 benea1h Ponds Forge)

2. Location plan. MlB 3 The main pool hall The focus of the complex is the 90m x 60m Programme pool hall. The main competition pool is The brief required completion of the building for packages. The management contractor was on 50m x 25m x 2m-3m deep with 2500 spectator the summer of 1990, so that a period of site by March 1988, only four months after the seats. The width will allow 10 lanes of 2.5m, acquaintance and use could be gained before appointment of the design team , giving a providing superb conditions for international the Games in July 1991 . With the appointment 31-month construction period. An analysis of swimming. Flexibility of use is provided by of the design team in late 1987, it was decided activities, together with the tight site conditions, power-operated floating floors, one at each end that the only way to achieve completion on time revealed that construction of the main pool hall of the pool, which can be lowered or tilted by was to adopt a management contract where the roof was critical. Early roof erection would hydraulic rams to provide a wide range of design and construction could take place as release the main work areas, unhindered by water depths. Two mobile pool dividers allow parallel activities with contracts let as a series of scattolding , formwork or fixed cranage. the international long course to be sub-divided into two x 25m short courses, water polo pitches, synchronized swimming areas, or three separate pools. The two areas which have floating floors can also allow a shallow-water teaching environment. The independent diving pool measures 25m x 16.Sm x 5.8m deep and has the most comprehensive range and number of boards in Great Britain. Leisure complex This contains 650m2 of leisure waters, compris­ ing a 25m warm-up pool and many fun features - a 1OOm slow river ride, two 80m flumes, a spa grotto and children's play area, plus a wave machine in the 25m pool. Associated facilities D-=-D-=-0-=-0-=-0-=-0 include a health suite with sauna, steam room , spa pool, and fitness suite. The leisure complex also houses a cafeteria, bar, restaurant and function suite, and an electronic museum is planned as a further visitor attraction.

Sports hall '-----L.-- The third element of the complex provides a 01Moving I bulkheads ---'-----' and floating floors multi-purpose space, 40m x 38m x 9m-12.5m high, able to cater for a wide range of multi-use activities. with power-operated, retractable International International seating for 1200. Planned uses embrace inter­ dMng pool 50m swimming pool national volley ball, tennis, badminton, basket­ ball, table tennis, gymnastics and indoor bowls. Community facilities including a creche and 0 ~ 50 shops are adjacent, as well as changing facilities with a fitness gym and ottices. Below the sports 5. Level 2 plan. hall. two levels provide parking for 170 cars.

Structural design

0 4m em 8. Pool hall section. Pool hall The original scheme wh ich won the design bridging and waterproof detailing considera­ tubular steel barrel vault, forming a three-pinned competition adopted an external four-masted tions. Then the diving pool was added and the arch over the 54m clear span. The roof contains system for the roof but. as the design masted structure finally abandoned as the sup­ 400 tonnes of structural steelwork. The main developed, misgivings arose about piercing ports could not be accommodated on the site. roof elements are tapered triangular trusses through the root membrane to support. the The concept changed to a vaulted roof design spanning diagonally between four concrete steelwork trusses, with the resulting cold with cross arches, developed as an 84m long supports on each side, with gable trusses 4 9. Forging. 10. Main trusses being lowered into casting. 11 . 12. Eaves casltng supported on temporary steelwork. 13. Steelwork roof supported at the crown on temporary towers. 14. Gable end casting. 15. Ridge truss detail.

16. Typical A-fram e/ terracing isometric, showing walkways and concrete ventilating ducts. spanning directly between the end supports to section. wh ich provide a simple support system temporary supports were removed and the roof complete the roof. The concrete supports are for the roof claddings and link the trusses allowed to settle into shape on its eight bearing A-frames with kentledges founded on bedrock. together, giving the same structural rigidity as points. Despite the complex nature of the roof, Thrusts of the roof are tied longitudinally along a shell roof. Edge and ridge trusses complete the planned three-month erection sequence the top of the seating and those across the the support for the grillage. The whole roof is was completed without mishap, allowing con­ building are resisted by the A-frame. covered with an insulated sandwich-type con­ struction of Hie main pool to follow. struction, clad with aluminium panels for The concrete terracing is supported by the main The roof trusses are welded to cast steel pinned acoustic absorbence. nodes at the crown and eaves of the roof; cast and secondary A-frame concrete supports steel was selected due to the complex geometry As already noted, the erection of the steel roof which also incorporate walkways and integral and the large forces to be transmitted, wh ile the was the key to the programme and this placed service ducts. The pool was designed in water­ form was chosen to provide direct load paths, the A-frame supports and other foundations on tight concrete to BSBOOl with no waterproof to give a castable shape, and to minimize the the critical path. Extensive former coal mine membrane, and a slip plane provided beneath weight. The material had an equivalent strength workings, 25m-30m beneath the site, had to be the ground-bearing base. No movement joints to the grade 50 steel used in the rest of the struc­ grouted as a preliminary contract, with parti­ were incorporated, due to problems on pre­ ture. The tube to casting connection was refined cular attention paid to early release of areas vious pools with tile failures. The pool con­ to ensure that the parts were thin enough to occupied by the massive support foundations. struction sequence was very tight, employing reduce heat loss in the body of the casting, and procedures similar to a factory control process castellated sockets detailed so that sufficient For erection of the roof. fi ve trestle towers were with small bays, strict limitations on casting weld length was provided. A cup and cap built to support the five cast steel nodes wh ich sequence, and well-prepared construction arrangement at these sockets allowed the run down the centre line of the pool, and other joints with a Hydrotite water seal. Pool toler­ trusses to be lowered directly into position with trestling erected around the A-frame piers to ances were also extremely tight and the pool adequate erection tolerances. cradle both the nodes and the trusses. The pre­ was made oversize to allow for these, and formed trusses were lowered into the sockets of temperature and shrinkage movement. For Interwoven between the trusses are the dia­ the nodes and welded together. Fixing the competition use, the bulkheads will be used to gonal curved infill grillages of tubular steel diagonal infill grillages followed , and finally the make the final adjustments. 5 Environmental services Outline Ponds Forge demanded a wide range of en­ vironmental conditions and services to cater for its diversity of activities. A services input to the design team was established during the corn· petition stage. and philosophies for servicing the building agreed at this time. These included the highly topical concept of wet and dry ducts to the pools, the many advantages of which were highlighted during the competition presen­ tation. Good design team consultation allowed early resolution of the fundamental services requirements for plantrooms, main distribution routes and services voids. Integration with the structure, detail and finishes was a high priority, and a great deal of time was spent ensuring this during design and construction. The final out­ come made all the effort worthwhile. Energy use in swimming pools is always a high profile consideration. This led to a specific development of the Oasys THERM program to be able to model swimming pools and deter· mine their energy consumption, utilizing a variety of systems and heat recovery methods. Corrosion problems were addressed from very early days with Arup Research & Development assisting in the selection of materials, finishes, and protective coatings. The mechanical and electrical specifications went to such lengths as to detail fittings, fi xings, finishes, paint types - even down to the use of brass nuts. bolts, and screws. Plantrooms Some 3600m2 of plant area has been provided throughout the complex for the services installa­ tions. The 2000m2 main basement plantroom houses most of the central equipment; a 900m2 water treatment plantroom is also located under the raised seating of the main pool hall. Three other air handling plantrooms are strategically sited elsewhere, simplifying distribution routes.

Central core design The complex central core area consists essen· tially of a leisure pool, a central area accom­ modating plantrooms. changing facilities. re­ freshment areas, and the main Rotunda entrance. The hydraulics of the leisure pool were initially tested at Salford University and the structure designed on similar principles to the main pool. Due to problems of filled ground in the area, the pool was suspended on supports taken to bedrock. At ground level a full-height curved glazed wall runs along the length of the pool. The design philosophy required a slender sup­ port structure for the roof and glazed wall: a series of light trusses supported by slender columns shaped at the head to give a pencil-like effect. Lateral stability is provided by bracing Sports hall design within the plane of the roof, tied to the adjacent The architectural concept called for the sports concrete structure. hall roof structure to give a column-free area of 4Sm x 3Sm x 12.Sm clearance at the highest The central area consists of three storeys and point. The roof spans 40m and consists of five a basement, the latter designed to BSB110 and inverted triangular space trusses, 2m deep, tanked. The structure is of flat slab construction supported on curved edge beams which are supported by columns with flared heads; this then carried by universal columns at Sm allowed clear service ru"ns and gave a practical centres. To support the roof cladding, secon· solution to varying ceiling heights. Delicate tied dary UB beams are provided, curved in profile. trusses form the roof and a feature is the large The members of the main trusses were made dog-legged staircase leading to the restaurant up of rolled hollow sections, which minimized and bar areas. jointing difficulties at complex node points, The Rotunda provides the main entrance to the facilitated steelwork fabrication, and provided District heating site at concourse level; its structure is reinforced consistent external member dimensions by The primary heat source is a city-wide district concrete slabs and beams to concourse level, varying the section wall thickness to suit design heating scheme which obtains its heat input with double-height steel columns above sup­ loadings. Stability is achieved by vertical from the city waste incineration plant some 2km porting beams centred on radial lines. The bracing within the wall construction, while hori· away. Sheffield were very keen to promote this pitched roof slopes to the centre and is sup· zontal bracing is provided within the plane of the 'green heat' scheme and many of the city centre ported by the series of columns on a circular roof on all four sides. public buildings are now connected to it. Two grid, with wind trusses provided in the plane of The structure below the games hall level is of 1900kW plate heat exchangers remove heat the roof and running across the front of the in situ concrete, one-way spanning, flat slabs from the district heating mains to supply the structure. These also provide restraint at the supported on shallow beams. An Sm x 4.9m building. The district heating supply tempera· head of the large glazed wall forming the main column grid was adopted to facilitate car lure is compensated and varies from 110°C to entrance elevation. parking. S5°C depending upon external temperature. 6 Main pool hall A major development is that the wet around coil heat recovery device on lighting and aesthetic requirements The ventilation system is based on duct has become a dry return air duct. the fresh air inlet/exhaust air outlet were met. Lux levels of 300, 500, the wet and dry duct principle. with the pool water and air completely sections of the air-handling units. and 1000 were provided for club, Concrete supply air and extract separate (Fig. 8). Control is simple: sequence control national, and international competition. ducts have been integrated into the of the run-around coil and main structure, resulting in a visually duct­ Smoke tests confirmed that the throw heating coil for temperature control, For televised events an illuminance of free pool hall space, leaving the roof of supply air over the underside of modulation of the fresh air/recirculated 1400 lux at pool level in the vertical structure in full view. the roof met all design expectations. pool air for humidity control. plane facing the cameras is achieved. A check on the humidity levels at Supply air is input along the longi· pool side and in the return air duct The lighting installation was required The luminaires comprise 400W metal tudinal edges of the space through showed no increase. thus proving to cater for a wide variety of levels to halide downlighters and 1500W slots designed to throw the warm dry that the new method of separation of meet the intended usage 'Of the pool metal halide floodlights. The former air over the whole of the pool roof. pool water and air is successful. ·hall. Many discussions were held are centrally positioned and provide Total supply air provides three air with the architects, sports bodies the two lower light levels. Phasing in changes per hour. Return air at pool· Energy use is minimized by (FINA, Federation internationale the fl oodlights provides the higher side level suppressed the high humidity modulating the recirculation of the volley ball) and TV broadcasting light levels including the all-important zone to the lower levels (Fig. A). pool hall air and the use of a run- companies to ensure that the stringent vertical plane illumination (Fig. C).

I Pool water return to I ' balance tank \ I Pool \ \

Pool B. Return air duct.

Air handling units

A. Pool hall ventilation. C. Pool hall lighting.

HY and LY distribution The fire alarm and detection system provides areas. Special features include: The main incoming supply to the complex is pro­ comprehensive coverage to the whole com­ • Audio induction loop for the hard of hearing vided by the Yorkshire Electricity Board, with a plex, with manual break glass units and auto­ in main pool hall, sports hall and function suites supply capability of 3.1MVA . The maximum matic smoke/heat detectors all linked to a • Sound reinforcement system within the main demand is in the region of 2.9MVA, which will central control panel in the Main Control Room . entrance, sports hall, leisure pool and main occur during the Games. From the HV con­ The building has a two-stage, two-phase pool, allowing local use of the PA system for sumers' intake panel there are two HV radial evacuation system, with the alert and evacuate general commentary, underwater speakers, circuits which feed three 1250kVA dry cast resin messages to each phase of the building being aerobics classes, etc. transformers. The LV distribution network com­ broadcast automatically by the PA system . prises two main switchboards feeding out to 23 Sprinklers for life safety are installed in high risk • Integration with the drowning alarm system switchrooms throughout the complex. areas together with dedicated mechanical and within the leisure pool and main pool Fire protection natural smoke ventilation systems. • Integration with the fire alarm system to Due to the central core area of the building Publlc address enable alert and evacuate messages to be exceeding the compartmentation requirements, The public address system is split into nine broadcast to all areas. fi re protection came under the close scrutinity zones. Facilities include eight multi-cassette Arup Acoustics assisted with the development of building control and the Fire Officer, who had decks, a pre-recorded message player and a of the PA system , particularly in counteracting a large influence on the extent of the systems master switching panel enabling any message the problems of reverberation times within the provided. or music to be broadcast to any combination of main halls and Forum. Energy Sports hall hour). high speed for events to management system Important factors considered in the provide free cooling (5.0 air changes A project of this size and complexity design of the sports ha11v entilation per hour). demanded a very flexible controls system were the wide range of A 'duct within a duct' type distribution system which could easily be adapted in use. A JEL Jelstar II occupancy of up to 1800 spectators was adopted to cater for .the low and during events, low air velocities system is installed, its main function high speed system, ensuring that being to control the HVAC plant across the playing arena. maintaining correct air jet velocities were main­ and equipment. Many other facili· the required unobstructed playing tained from the inlet drum louvres. ties are linked, such as fire alarms, zone (40m x 40m x 12.5m), and the Low speed uses one section of the pool filtration monitoring, smoke height of the hall. duct and 50% of the vertical dis­ Architectural control, lighting control , sprinkler panelling ----

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8 Concluslon Already the competition pools are being heralded as world class. Prior to the Games, Ponds Forge hosted the European Diving Cup and World Swimming Cup. Three world records have been broken since the centre was first used at Easter 1991. an unprecedented event in Great Britain. HRH The Princess Royal opened the complex officially on 17 April 1991 . and joined a capacity audience of enthusiastic parents and children at a Sheffield schools swimming gala. The omens all suggest both the complex and the Games will be a resounding success. Credits Client: Sheffield for Health Architect: FaulknerBrowns • Structural engineers: Ove Arup & Partners Newcastle Mechanical & electrical engineers: Ove Arup & Partners Manchester Quantity surveyors: Gleeds Management contractor· Mowlem Management Ltd .

23. 28. 29. Rotunda entrance. 24. Leisure pool elevation. 25. Atrium 26. Steelwork detail: leisure pool. 27 Pool hall elevation. 30. Diving pool. 31 . 34. Pool hall. 32. D1v1ng boards. 33. Scoreboard.

Photo credits: 1. 4, 18, 32: Jane Richardson 3: John Holt 7, 12, 13, 19, 20, 23, 25,26, 28, 30, 31 , 33, 34: Peter Mack1nven 11 · Harry Sowden 14: R.J. Davis. Thomas Telford Ltd. 15: John Gregory 17, 24, 27, 29: Martin Butterworth 21 , 22. T.O'Malley 34 'i7

9 New Guesten Hall Architect: Associated Architects

Background load, set eccentrically to In The Arup Journal, March 1969, Gary Marshall counterbalance the roof thrust. John Martin wrote about the before the bare roof was erected. inception of the Avoncroft Museum The final stressing was carried out of Buildings at Bromsgrove, Worcs .. before the boarding and tiling. and in particular the 14th century The gable end framing is of Guesten Hall roof which 1t was then tradibonal timber construction above hoped would soon be re-erected eaves level, but is supported by a over a purpose-built structure at triangular section truss. This Avoncroft. Now, 22 years later, and combines the provision of a wind after languishing for 17 years under girder with framing tor viewing a temporary asbestos roof, the old panels and gives a clear span timber trusses are at last in position between side walls. The truss is over a new building. formed of limber members Joined at Design concept nodal connections. its clean lines To echo the original Guesten Hall in harmonizing well with the exterior of Worcester. the Avoncroft building is the building, and it provides an to be a visitor centre. and will form interes!lng comparison with the the entrance to the Museum. The traditional trusses on view within. The design parameters were dictated by trusses were manufactured by Mero the required use, by the need to to our design, but using their display the roof adequately, and by proprietary steel-to-timber the structural demands of the roof connections. All glazing and doors trusses themselves. Possible full­ below the truss may be removed in w1dth entries at each end and the future, depending on the growth inclined viewing panels necessitated of the Museum. independent side walls; the gable Conclusion end framing offered several options The New Guesten Hall was officially but had to provide full width support opened on 16 November 1990, against vertical loads and wind marking the beginning of a new forces. The weight of the roof is chapter in a long history. Ongoing is considerable and the collar tie works the extension to one side of the Hall, as a compression strut rather than a which will be built when funds true tie. providing the feet or the permit; sponsors are being invited truss are restrained. In this form , the for the decorative corbels to the trusses perform satisfactorily, but if main trusses. allowed to spread. the timbers are over-stressed and the joints suspect.

It was also considered desirable to Ker data use modern technology within the Roof new building as a counterpoint to Span of trusses. 10.56m the old structure, whilst not Truss centres: 2.43m detracting from it. Number of bays: 8 Design solution Truss reachons. 44kN verttcal. 30kN honzontal The side walls, each 890mm thick Credits Main ratter 450mm x 1BOmm oak and 6m high, were constructed of Ghent Walls post-tensioned diaphragm brickwork. Avoncrolt Museum of Buildings length: 24 .18m Utilizing some 46 Oywidag bars in Architect: Thickness: 0.89m each wall, post-tensioning proved to Associated Archrtects Height: 6.45m be a cost-effective solution. The bars Structural engmeers.· Prestressmg: 46 28mm dtameter were stressed to 75% of their final Ove Arup &Partners Nottingham Gewi bars giving 575T per waif 10 Hong Kong Park Aviary Ian Robinson Brian Forster

Introduction Ove Arup & Partners Hong Kong, in collabora­ tion with the London Lightweight Structures Group, were appointed in 1988 as consultant structural and geotechnical engineers for the design of the Aviary, conceived as one of the major attractions at the new Hong Kong Park. Although the Territory has relatively large areas of park, most are outside the residential and commercial zones, due to the demand for building space. Hong Kong Park, a joint development by the Urban Council and the Royal Hong Kong Jockey Club, is one effort to redress the balance. It is situated in the Central District of Hong Kong Island between Cotton Tree Drive and Kennedy Road, formerly the site of the Victoria Barracks. The Park will cover 100 OOOm2 and include the Aviary, a green· house, a t'ai chi garden, lakes, a children's play area. and a visual arts centre, all surrounded by some of Hong Kong's most impressive buildings. The concept The client's original concept for the Aviary was indicative only: a 3000m2 enclosure within Three major arches were used, stabilized by in two directions forming equal length quadri­ which birds could fly freely in a sub-tropical doubly-curved cable net surfaces stressed and laterals, each of which is uniquely skewed. environment. To achieve this the site was anchored at points round the site boundary at Within each net the node-to-node length is a chosen carefully, a steep-sided valley, 62m ground level. The relative stiffnesses of arch and constant 2.4m, important for fitting the mesh to wide at its broadest point, which twists in plan cable net influence the size of bending moments the cable net. The mesh wire themselves form and whose sides fall at differing rates. It and axial forces which develop within the a net of equal length quadrilaterals which are descends 12m through the ?Sm of the Aviary's arches. The tubes comprising the arches had progressively skewed to conform to the cable length. A natural stormwater course passes diameters of 560mm, 403mm and 323mm, net, made possible by using a woven mesh. through the valley, which is densely wooded giving span/depth ratios of 110. The grade SOC The cable pairs in both directions are clamped with a variety of mature species, the tallest being steel used was formed to smooth radii by heat together at their crossover points by stainless approximately 13m. The client required most of induction bending. A fourth arch was later steel castings with shaped grooves. to maintain those trees within the area of the new Aviary to introduced at the head of the valley to accom­ the 2.4m dimension and provide structural be retained. modate the entrance lock. All the arches are loadbearing capacity between upper and lower Preliminary studies by a Hong Kong-based supported by hand-dug caissons bearing on cable pairs . One central bolt holds the two cable architect proposed a conventional mast and weathered granite. At the base of the three pairs together, permitting rotation during erec­ mesh enclosure, typical of other aviaries major arches, spherical bearings accommodate tion and in service. throughout the world, with the public passing the rotations that can occur under wind loading and during construction. Attachment of each cable pair to an arch is by through on elevated walkways just below tree a split casting incorporating a central eye bolt canopy level. The disadvantage with this, how­ The cable nets are built up from pairs of 14mm with loose cross pin and a radial spherical plain ever, was that the construction would have or 16mm diameter stainless steel cables running bearing. Th is pin enables equalization of load necessitated the removal of many of the trees. in the two cables. A new approach was therefore required. The ends of each cable pair passing across the The Aviary had to be seen as a landscape valley are equipped with tubular rigging screws element and to this end its general form and to allow prestressing. This is required to ensure shape were influenced by the site's natural land­ that no cables become slack as a result of move­ form. By spanning clear across with arches. the ment during mesh installation or whilst in ser­ valley's shape in plan and section would be vice. A cross-head links the two cables to a reflected by the structure. A surface of wire single eye-bar and via a bearing onto the cir­ mesh suspended between the arches would cular baseplate. Holding down bolts to the create the enclosure. The retention of the baseplates are cast into concrete piers pro­ mature trees, and a requirement that the peri­ jecting from a continuous boundary wall, which meter-enclosing concrete kerb should follow the are anchored into the bedrock by minipiles. constantly changing ground level by little more than O.Sm , were now possible. 2. Anchorage of cables passing across valley The mesh aperture size chosen by the client was with rigging screws for prestressing. particularly small, 12mm x 12mm compared to 3. Multiple cable anchorage. a more usual 60mm x 1 OOmm. This size is not, as one would expect, to prevent birds escaping, but to stop rodent infestation, found to be a major problem in another Hong Kong aviary. This choice became the largest single influence on the scale of forces applied to the structure and foundations. The design Arups were given freedom to develop the whole concept of the enclosure and carried this out using a 1/100 scale topographic model. It seemed important that the perception of scale within the valley should continue to be by reference to the trees, so there are no columns. The use of simple, slender arches stops the 2. structure and enclosure competing for attention. 11 4. Showing cable cross-over clamp, cable connection to arch and hanger bar system which connects cable net to mesh panels.

The mesh envelope was built up from individual The calculation of surface geomery was made Erection strips of woven crimped stainless steel wire using FABCAB. a non-linear tension structure The valley depth, and restrictions on the re­ mesh, suspended below the cable nets and program. One primary object was to control the moval of trees. initially appeared to rule out the arches by a series of hanger bars wh ich follow skew angle changes within the cable net cells. use of scaffolding. except for supporting the the longitudinal edges of the mesh panels. another to define the precise points where the arches during fabrication. At tender it was there­ D-shackles connect the mesh to the hangers via last cable elements cross the concrete and arch fore envisaged that once the arches were in reinforcing edge strips welded to the mesh boundaries. The specific geometry of the place -and at least one cable present between panel. and are of a size to maintain a maximum boundary concrete wall was derived from land arches. a system of pulleys could be used to gap of 12mm. survey drawings using MOSS. pass the remaining cables across the valley and The structure was analyzed with FABLON , a between arches. The mesh would then be non-linear space frame analysis program. on a erected similarly. In Hong Kong, scaffolding has full arch and cable •net model having 1200 a different meaning from many other places. nodes and 1800 elements. Stability analyses Bamboo, light. strong. and flexible. is used were also performed using FABLON. Wind without any planking and erected at great forces were created using specially written speed. This being the case. the contractor subroutines allowing automatically for wind chose to scaffold the entire site. producing what direction. surface inclination, drag coefficient. appeared to be a mould for the ensuing Aviary and distinguishing between windward and envelope, whilst still allowing work at the valley leeward positions. floor to continue during erection.

12 The arches arrived in sections up to 6m long, ensure they would not go slack due to move· were free to rotate; hence careful monitoring and were butt·welded in position. At the same ments during mesh installation, and also in ser· of arch location was essential. The simplest time the cables were being cut to predeter· vice. This was done cyclically, initially in three method used a series of plumbobs providing mined lengths in matched pairs and the relevant stages, tensioning the cables to approximately essential information, followed by a survey of half of the cross·over clamps and rigging screws 1SkN per pair by reducing in length those pass· points on the arches themselves. fixed in position. These cables were then con· ing across the valley through the use of rigging With tensioning complete, sample cable forces nected to the arches and each other in a slack screws swaged to their ends. Throughout th is were measured to check the accuracy of the condition. The cables had to be prestressed to process the arches, although propped initially, analytical predictions. Minor adjustments cor· reeled any unacceptable force distribution or out·of·tolerance of arch location. The mesh installation also required tensioning to prevent 'flutter' at everyday wind speeds and to create a taut, smooth appearance. Th is necessitated two processes. The first was to pull the mesh taut with an applied tension of approximately 1kN/m at the boundary, and then clamp to the boundary wall. This took most of the sag out of the mesh panels. A slightly greater tension was required , and calculated destress· ing of some cables by increasing their length was used. The effect of this operation was to raise the cable net and hence the mesh. As the latter is clamped at the boundary wall and of fixed length, increased tension resulted . The completed structure Within the completed aviary there is a sense of space and calm. The intention was to design an unassertive structure, and although the largest arch rises 30m above the bottom of the valley, the aviary does not dominate the landscape. After extensive planting, the site will be allowed to mature prior to the introduction of 150 species of birds indigenous to South East Asia's sub· tropical forests. Once the birds have become acclimatized, the Aviary will open to the public some time early in 1992. Credits Client: Royal Hong Kong Jockey Club Structural and geotechnical engineers: Ove Arup & Partners Architect: Wong Tung & Partners Ltd. Main contractor: Dragages et Travaux Publics Erection contractor: Kent Ho Engineering Works Photos: 1·3, 6·10: Bird Wong. 13 Weatherstone Riding Ring Architect: Cooper Robertson & Partners Guy Nordenson Liam O' Hanlon

Introduction Weatherstone Riding Ring is an indoor facility at a private client's country estate in Northern Connecticut. The building is BOit x 2001t 1 in overall area with the roof rising from 161t at the eaves to 401t at the ridge. The ring itself forms an BOit x 1601t rectangle plus a 401t radius semi­ circle at one end. Adjacent are stables for 12 horses and living facilities for the manager and groom. The architect. Jaquelin Robertson of Cooper Robertson & Partners, sought a structure for the roof that was of a uniform density, rather than consisting of parallel trusses, arches, or portals. His preferred material was wood. In addition it had to accommodate a 41t high clerestory all around, thus creating a 321t wide gable about the ridge separated by the clerestory from a surrounding 241t sloping apron. The design of the structure was undertaken by the New York office of Ove Arup & Partners; the outcome of our deliberations with the architect consisted of a series of wood and steel trusses spanning the rectangular portion of the plan and a pair of half cones (apron and gable) at the end 'cap' (Fig. 1), organized on an Bit module in all directions. Columns are double th is height and the same distance, 161t, apart, with the truss rising a further 161t over the 241t apron and 41t to the ridge from the top of the clerestory (Figs. 2 & 3). Trusses =

Colour key for all diagrams - Glulam - Wire. steel rod or pipe members - Clerestory or stiffening truss ----- Gross bracing (rod) 1. Plan of roof structure. - Ridge framing and diagonals (glulam)

14 2. Typical truss.

3 Interior View looking toward front entry 4. Tension chord and diagonal 'stirrup' connection. 5. Close-up of 'stirrup' connection 6. Typical connection at top of columns 7 Exterior view during construction with main and clerestory trusses in place

15 The cap To maintain the structure's uniformity, it was important that the scale and density of that part of the roof around the cap be constant. To achieve this the cap was treated as a framed half-dome relying on a tension ring of double tie­ rods along the eave, and a compression ring consisting of the clerestory truss and an 8ft deep, lightly braced, glulam stiffening truss (Fig. 8) . The latter was required to allow for un­ balanced live loading that would cause bending in the compression ring . The top portion of the cap, above the clerestory, is a simple arrange­ ment of ribs radiating from the end of the ridge towards the top of the clerestory (Fig. 9) . The effect of this approach was to allow the use of ribs similar in size to the compression members of the main trusses, and eliminate the need for a large truss across the end of the cap. The results were large tension and compression loads delivered to the eave and clerestory. On the eaves these are resisted by the tie rod bracing between the columns. The compres­ sion load to the clerestory truss also finds its way to the rod bracing via the connection to the com­ pression glulam members beneath the apron. The tendency of the two apron portions to splay apart (in plan) as a result of these force couples is resisted by a tie between· the columns em ­ bedded in the wall at the end opposite the cap. Stablllty 8. Computer plot of the cap, and below 9. Interior view of end cap. Careful evaluation of all extreme load condi· lions, including 100 year wind and severe un­ balanced snow load cases, revealed that the tensions in the rods would not be overcome. Overall stability is provided by six bays of rod cross-bracing, two on each side and two at the cap (Fig. 1). The timber decking overlaid with %in plywood and the compression members (forming a truss in plan) together act as a diaphragm to distribute the lateral loads to the wind bracing. The clerestory truss ties the gable roof to the apron diaphragm. Under the effect of unbalanced snow loads or cross winds the main trusses will deflect, caus­ ing bending in the horizontal cross compression member (since the truss is not fully triangulated the light wires will relax) . To resist this bending, a horizontal 'flitch' plate is inserted as an exten· sion of the A frame/cross member joint. Decking The roof surface consists of tongue and groove laminate decking 3 'h in thick. overlaid with ply· wood, exposed on the underside. The spans are up to 16ft on the apron. The decking served a useful role, acting as a deep 'horizontal' beam Conclusion along the aprons. This contributed to the resis­ All the members and connections were fabri· A sequenced pretensioning schedule was pre­ tance of the structure to vertical loads by cated off-site to the required dimensions. pared in conjunction with the glulam fabricator distributing these to the end wall and cap brac­ Tolerances were quite small. The structure was and the contractor to obtain the final geometry ing, and thereby serving as a kind of abutment erected off a full scaffolding and was completed after the shoring was removed. The geometry for the trusses to arch. in 10 weeks. All the bolt holes were pre-drilled. was achieved to with in 'A in tolerance all round. Credits Client: Private cltent Architect: Cooper Robertson & Partners Structural engineer: Ove Arup & Partners Services consultant: John L. Altieri Consulting Engineers. Norwalk, Connecticut Main contractor: Herbert Construction, New York G/ulam fabricator: Unadilla Laminated Products. Unadilla, New York Photos: Courtesy the architects

10. Weatherstone R1d1ng Ring , stables and living facilities.

16 Introduction The tlmet•ble The design The Arts Center is the principal component in As is common in the USA, the design period was As well as the Arts Center, the site will eventually the 120-acre masterplanned development of split into three distinct phases, with costings and contain an office park, an hotel, and a 75-acre Cerritos city centre. Currently under construc­ formal presentations to the client at the end of regional shopping centre. tion. with completion due at the end of 1991 , it each. Before a job goes out to bid (tender). it An urban context was thus missing, apart from will provide a wide variety of performance areas, is subjected to a formal review process known some undifferentiated office blocks and an community meeting rooms and ancillary as plan check. The Building and Safety Division ocean of car parking. This was in contrast to spaces. of Los Angeles County Engineer-Facilities car­ architect Barton Myers' previous and highly Cerritos, a forward-thinking Southern California ried out this work on behalf of Cerritos, carefully successful theatre in Portland, Oregon. which city with a population of 60 OOO . could neither reviewing the design drawings and specifica­ occupied a very dense city centre site, sand­ afford nor support three separate theatres and tions for code compliance. wiched between two buildings listed on the an exhibition area. An early study by Theatre National Register of Historical Buildings. Schematic design March to Nov. 1987 Projects Consultants had identified a need for Design development Dec. 1987 to March 1988 Thus the first challenge to the architects was to three different spaces. suitable for music, drama create a sense of place. This they did by arrang­ and trade shows. This study showed how, using Construction documents March 1988 to Jan. 1989 1 ing the Arts Center as a series of pavilions with Northampton's Derngate Centre as a model, Plan check Phase 1 Completed June 1989 gardens and courtyards. The benign climate the city could afford to construct a multi-purpose Plan check Phase 2 Completed Jan. 1990 allows designers this freedom, and the forms. hall that would satisfy its cultural ambitions. Bid May 1989 materials and details used are rooted in the When it opens in 1992, Cerritos will have a traditions of Southern California regionalism . Construction began Sept. 1989 facility that is unique in North America. Its Barton Myers had several images in mind as the technical innovations will make it one of the most Flytower topped out Jan. 1991 massing studies progressed: the clustering of sophisticated theatre spaces on the continent. Auditorium toppinQ out ceremony May 1991 buildings in a Mediterranean village; Bertram Goodhue's flamboyant designs for the 1915 2. Plan showing Panama-California Exposition in San Diego, the sjx major buildings. now known as Balboa Park; and the spirited shapes, volumes, roofs and shadows of Los Angeles' chateau buildings. A particular problem was how to deal architec­ turally, in a parking lot, with the large mass of the flytower. The solution was to cascade the buildings' roofs and towers down to garden walls, thus mediating to a pedestrian scale; the garden walls also insulate the pedestrians within Key from the cars without. The courtyards thus 1. Large meeting room formed are well-suited for outdoor receptions. 2. Small meeting room Each major building component has pyramid­ 3. Offices shaped roofs and many also support tall flag­ 4. Lobby poles. There is much rooftop lighting and the 5. Plant and services Center, wh ich is visible from the nearby free­ 6. Auditorium way, will have a beacon quality (Fig. 1). 7. Stage a: Dressing rooms The architects believe very strongly that place 9. Scenery store itself is an important part of theatre-going, and 10. Loading have deliberately striven for a cheerful, welcom­ 11. Stairs ing, carnival-like building. To this end, much 12. Poets' garden attention has been given to the external clad­ 13. Entry court ding. As well as a creamy white stucco, there is much banded stonework, in some ways reminiscent of James Stirling's Staatsgalerie in Stuttgart. Polished red granite and French I) limestone are used. The roofs are clad in highly coloured and patterned ceramic tiles, com­ puter-designed specially for the project by April Greiman. The six major buildings (Fig. 2) are the auditorium and sidestage; the actors' block; the lobby and box office tower; the large meeting room; the office block and small meeting room ; and the mechanical tower. 17 A. Banquet. 639Qft 2 B. Arena. 1824 seats C. Concert, 1719 seats D. Drama, 972 seats E. Lyric, 1416seats

3. The auditorium: showing the five basic configurations.

The auditorium flytower. In the arena and banquet configura­ Four lifts are used to reconfigure the floor. form­ The heart of the project is the auditorium. It tions the occupants should feel that they are in ing as needed a forestage (drama mode), an offers unparalleled flexibility, with five basic con­ one room. This is achieved in two ways. The fi rst orchestra pit, or an extension to the orchestra figurations (Fig. 3) transforming the auditorium 's is by stepping the seating tower boxes (Fig. 4). level seating area. The lifts also support seating seating arrangement, sight lines and acoustics This follows closely the rake of the two balconies wagons wh ich may be lowered to a storage area by the use of moveable seating towers, lifts, two so that there is no abrupt transition in the side beneath the stage. A fifth lift at the rear of the proscenium lines (and two fire curtains), a flown seating as the audience wraps around from the orchestra level is used to exchange seating for acoustical concert ceiling above the stage, and edges of the balconies to the sides of the stage. an in-house sound mixing location. a device known as the flipper. The ceiling treatment is the second device used The seating wagons move on air-powered The arena and concert configurations allow for to give the feeling of one room. Suspended castors, as do the four clusters of seating centripetal viewing of a central stage. The lyric with in the flytower is a flown concert ceiling towers: the auditorium side towers, the side format is designed for opera and large-scale made of three large steel and laminated timber stage towers, the proscenium towers and the musical productions. The drama format is simi­ honeycomb Pc!nels. When not needed they are rear stage tower. Microprocessors co-ordinate lar to the lyric, but uses the forward proscenium , rotated to lie in vertical planes and hoisted elec­ the movements of lifts and seating towers so a forestage (the orchestra lift) , and closes the top trically to the underside of the gridiron, an open that, for example, the side stage towers do not balcony. The flat floor configuration houses steel platform high above the stage. For the con­ tumble into the orchestra pit. community events, banquets, and trade shows. cert, arena and banquet configurations, the The auditorium side towers (Fig . 6) are used in panels are lowered into place, rotated and two positions, parallel with the auditorium walls Architecturally, Barton Myers had a choice locked together at the same level as the lighting when designing the interior of the auditorium: in concert mode and rotated 15 ° inwards in lyric bridges and ceiling in the auditorium. In addition or drama mode. Movement is by electric to celebrate the technology of the moving parts to its visual effect, the ceiling closes off the or to make each configuration look permanent. winches. Hydraulic rams with steel pipe arms absorptive soft goods in the stage house, located between the backs of the towers and the He chose the latter. maximizing reverberation. Fig. 5 shows the side walls of the auditorium provide seismic At its largest, in concert configuration, the shoe­ flipper, an unusual and maybe unique item of restraint. The architectural transition is achieved box shape brings to mind the Musikvereinsaal theatrical hardware. An integral part of the fire by folding capitals. separation between stage and auditorium , it is in Vienna. The seating towers form traditional When the auditorium seating towers (150 OOOlb boxes from which one can see and be seen. The attached to the front proscenium and rotates on pivots to three positions: downwards each) are rotated away from the side walls, box fronts help define the volume of the room , hinged walkways known as jet ways link which is richly finished in light ash , a darker (drama mode) creates a proscenium arch; angled (lyric mode) forms a second proscenium audience access doors to the rear of the seating stained ash , cherry and olive green painted towers. Raising, lowering and tracking of the jet steel. The seating towers are constructed of arch further upstage; whilst horizontal (banquet, arena and concert modes) links the concert ceil­ ways is electrically powered, with an interlock tubular steel frames and lightweight concrete on system to prevent deployment at undesirable metal deck floors. ing to the auditorium ceiling. The flipper weighs approximately 27 OOOlb and is moved to its times. A challenge to the architects lay in the contrast three preset working positions by an electric The proscenium (43 OOOlb) and side stage between the proscenium configurations (drama motor - horizontal to vertical in about two (140 OOOlb) seating towers are moved manually and lyric) and the audience-in-the-round or flat minutes. Tracking side panels suspended from or by electric tow tractor on air castors between floor configurations (concert, arena and ban­ the flying system adjust the proscenium width floor lock down positions (two for the side stage quet). In the former there are two distinct between lyric (4511 wide) and drama (3511 wide) towers and four for the proscenium towers), volumes, the auditorium and the stagehouse or formats. which provide seismic restraint.

Side tower relates 15° inward for Proscenium wall lyric and drama conhgurat1ons

Screwiack

truss

A,pper ­ ho(lzontal

Orchestra pot hit raises flush with floo< for arena and flat lloor conf,gurat,ons

Flipper - vertJcal Seanng tower stores at rear ol stage for lync and drama configurations ------' Rear tower moves lorward to provide seaung lor arena or theatre-,n·the-round ------' 5. Flipper adjustment mechanism 4. Stepped seating tower boxes. for proscenium stage opening. 6. Seating tower movement patterns. 7. Analysis of dynamic model. 18 The rear stage seating tower (225 OOOlb) is The lobby were driven prestressed precast concrete piles much shallower front to back than the other Deliberately set off-axis, the lobby is much more 14in square, varying from 2011 to 6011 in length. towers, and requires stabilization even when in than a place of assembly and dispersal. Its three The geotechnical engineer designed a per­ transit. It is moved by an electric winch that hauls upper floors overlook an internal courtyard manent pumped dewatering system for the site, cables running beneath the stage floor. From which can be used as a performance space. but nevertheless the piles beneath the deep each tower base eight T-bar guides travel in floor Leading up to circulation spaces behind the orchestra pits were designed to cope with full slots and lock into position when it is stationary. auditorium balconies is a monumental staircase hydrostatic uplift minus the weight of the pits, in Power, lighting and sound are delivered by of cast in situ concrete, the set piece of the lobby, case the dewatering pumps failed. cables supported by a cantilever arm pivoting whose roof is just a little lower than that of the Seismic design concept from the rear wall. auditorium. Attached to one corner of the lobby The Center is arranged as a series of five Acoustically, the auditorium is transformed by is the 6011 tall steel and glass box office tower. seismically separated structures. As a result, moving parts that change its volume and the Cost cutting reduced the lobby space, but it is each building apart from the auditorium has a reflectivity of its surfaces. The moveable concert still generous when compared with those of, for regular layout of its lateral system, and could ceiling has already been mentioned; a free­ example, New York's Broadway Theatres. The therefore be designed using the static lateral standing orchestra shell may also be used to mild Southern California climate allows the force procedures of the Uniform Building Code. reflect sound towards the audience. Provided gardens and courtyards to be used as exten­ The separations also enabled each building to within the auditorium are acoustic banners and sions of the lobby. From outside it can be have a lateral system compatible with its func­ curtains which are intended to adjust the rever­ approached in opposite directions: by car or by tion. For example, the mechanical tower uses beration to accommodate a variety of uses and foot via a walled entry court from the parking lot. a steel ductile moment frame which allows air occupancies. Electrically operated from a con­ The large meeting room flow through the exterior screen wall to the air­ trol panel in the sound room , the banners retract A tall, single-storey, column-free area, this can handling units, and permits easy installation or vertically into pockets beneath the ceiling line. accommodate up to 400 for banquets. A grid removal of large equipment; the auditorium One set of curtains retracts horizontally into of tracks for operable partitions allows it to be shear walls provide lateral strength and stiffness pockets within the roof void, whilst curtains at divided into as many as five individual, sound­ at the same time as acoustical mass. the rear of each box withdraw into the columns isolated meeting rooms. The room is theatrically Auditorium seismic design between boxes. equipped with lighting and sound systems, Prior to the 1988 Uniform Building Code, the Curved concave surfaces such as balcony rigging trusses, self-climbing chain hoists, requirement for dynamic analysis was deter­ fronts are broken down to a finer scale whose draperies, a portable stage platform and a port­ mined by the building official who had jurisdic­ convex curvature and hard wooden surfaces able dance floor. A telescopic seating unit pro­ tion . For this project it was agreed during the help scatter sound and thus avoid unwanted vides seats for 160. The room can be used as schematic design phase that, due to the focussing. a rehearsal space while the main auditorium is building's box-like nature. it could be designed The boxes have three principal planes: the front, being used, as well as by small theatre groups using equivalent static lateral force procedures which visually defines the volume of the audi­ or musical ensembles. Being close to the hotel, and the most stringent K-factor, 1.33. The torium; the back, a perforated metal screen it can serve as an extra conference area. A two­ building could then be designed for an acoustically transparent at the upper boxes but storey wing houses a kitchen and some assumed distribution of mass. reflective near the stage to support the musi­ bathrooms. When the building was submitted for plan check cians; and the rear of the tower, which is similarly Office block and small meeting room a year later, the 1988 Uniform Building Code treated. Low frequency sound passes through This small , two-storey building for the Center's had just been issued, and under its provision a the screens. bounces off the side walls of the administrative staff opens onto a walled garden dynamic analysis was required for the audi· auditorium, and re-enters the room . High which it shares with the large meeting room . torium building. The owner then authorized frequency sound is reflected and scattered by The mechanlcal tower Arups to carry this out, to verify the adequacy the wooden panels on the box fronts. To pre­ This is a five-storey, square building housing of the original static analysis design. Our serve low frequency energy, the walls and roof chillers, boilers, fans, cooling towers and air· analysis showed that once the dynamic base of the auditorium and flytower are massive and handlers. The concept of a completely shear was scaled to meet the static base shear, reflective, either reinforced concrete or re­ separate, mechanically dedicated structure as required by code, the stress levels and inforced solid-grouted masonry. This posed springs from the need for acoustical isolation behaviour of the structure closely matched major structural challenges both for design and and the architectural desire to avoid a single those predicted with the static analysis. The erection. monolith. Problems of air intake, exhaust, dynamic analysis also showed some localized All public bathrooms are in their own seismically access to equipment and acoustical separation excitation of the flytower columns, in excess of and acoustically separated box, with a floating are all solved by the presence of the mechanical that anticipated from the static analysis. As a slab on a sandbed, at ground level adjacent to tower. Its mass, taller than everything except the result, two columns and some details were re­ the curved rear wall of the auditorium. All auditorium and flytower, and topped by four vised, and the project was released for bid. associated pipe and ductwork is vibration­ small pyramid roofs and a flagpole, is an essen­ Our dynamic model was constructed and its isolated. All major plant is separately housed in tial part of the cascade of roofs and towers and response spectrum analyzed using SAP90, a the mechanical tower, seismically and vibration­ shadows that help so large a theatre sit com­ commercially available software package. The separated from the auditorium structure. fortably in its surroundings. model had 880 nodes, 751 shell elements, 387 The auditorium contains sophisticated sound Engineering frame elements and 4261 degrees of freedom. and lighting systems: theatre sound; technical In California matters are arranged a little dif­ 40 vibrational modes were combined to achieve intercom; paging and show relay; video; a ferently from the UK. Firstly, most of Southern at least 90% mass participation. The building master antenna television system; control units California is in Seismic Zone 4 as defined by the weighs approximately 16 400 kips and the containing communications facilities for stage Uniform Building Code. This specifies substan­ design base shear from the maximum probable management and technical usage; a hard-of­ tial lateral forces for which buildings are to be earthquake is 3825 kips. Fig . 7 shows graphical hearing system; and a portable sound system. designed. Secondly, the geotechnical investi­ output from the analysis. The theatre is one of only two in California gation and the selection of the type and capacity Auditorium designed to be used for major recording ses­ of the foundations are the responsibility of The transverse shear walls are full height, 12in sions. Stringent criteria were applied to the independent geotechnical engineers. thick, reinforced concrete, varying in strength 2 design and detailing of the air distribution Foundations from 3000-5000lb/in . As Fig. 8 shows. the system. More than 750 dimmers are used to The soils investigation by Moore and Taber. walls at the back of the stage step. Arups control the lighting. geotechnical engineers, revealed silts, clays designed the temporary props for these walls, and sands, with a design ground water level and in fact for the whole auditorium structure, only 411 below the orchestra slab on grade. The under an appointment by the general con­ recommended foundations for all buildings tractor. The proscenium wall is 95ft tall with an opening 4211 high x 9411 wide. The curved lobby wall contains substantial reinforced concrete pilasters to support the balcony cantilevers. Steel pilaster columns provide out-of-plane sup­ port for the back of stage wall.

8. South-north section. 19 36 in diameter supply ducts Air handler Cooling for tower aud1tonum

Ad1ustable threaded rod 241n s Alr ~ handlers lor lobby

s Air FteKible handler ~ connectors lor control Maintenance minimum room 90 1n Seating tower Water Boiler heater

9 Vertical section through aud1tonum 10. Air supply 11 . Mechanical tower showing equipment sealing tower plenum and diffuser to auditorium seating towers. on the five different levels.

The longitudinal auditorium walls began life as The 2811 square x 7211 tall mechanical tower has towers at the top of the mechanical tower. Water reinforced concrete with steel pilasters but were lightweight concrete on metal deck floors sup­ enters at 95 ° F and leaves at 85 °F. cost-driven to reinforced masonry with em­ ported by a steel frame. The lateral system is a Hot water is supplied by two natural gas-fired bedded steel pilasters for out-of-plane support perimeter ductile moment frame. It is clad with boilers. Supply temperature is 185 ° F and return of the wall and gravity support of the main steel a screen wall of reinforced masonry panels temperature 165°F. roof trusses. Erection of a composite masonry made of square blocks with openings in them . The auditorium is served by a constant volume, and steel wall has been a challenge for the Mech•nlc•I systems general contractor and his subcontractors. single-zone system with supply and return fans. The special features are: Air is at high level from specially designed The three warped and curved balconies are • The stringent acoustical design criteria sidewall plena diffusers and extracted low down supported by deep radial, sloping, tapering, • The flexible ductwork for the moveable the auditorium sides and beneath the balconies. curved beams that cantilever from the rear wall seating towers pilasters. The balconies are cast as dished slabs Large supply and return ducts link the air onto which steps are later cast, in order to • The purpose-built supply plenum diffusers in handlers in the mechanical tower with the roof the auditorium, stage and large meeting room space above the auditorium ceiling, where duct­ achieve the best control of final balcony eleva­ (Fig. 9) tions for the seating sight lines. work is carefully integrated with roof trusses. • Compliance with California's strict Title 24 The auditorium and flytower roofs are supported energy requirements Each group of supply and extract terminations is fed from the main air-handling units via a by steel N-trusses. The flat flytower roof, of • The seismic anchorage and restraint needed hardrock concrete on metal deck, has 611 deep separate, self-balancing, ductwork system with to deal with Seismic Zone 4 trusses spanning from proscenium to rear stage no dampers. All auditorium air termination wall. Suspended from these trusses are the • The structurally separated mechanical tower devices are specially designed to provide the gridiron, three levels of catwalks, and the loft • The stage sprinklers. required air distribution with minimum gener­ blocks. The headsteel spans 72ft, supporting The acoustical performance criteria were speci­ ated noise. Fig. 1O shows the folding and 191 kips horizontally and 231 kips vertically. fied by Kirkegaard Associates in terms of room extending ductwork for the auditorium seating Most of its load comes from the pulleys over criteria (AC) and preferred noise criteria (PNC) towers. which the scenery counterweight cables run. and are listed in Table 1. Both AC and PNC are The lobby also uses a constant volume, single­ The vaulted auditorium roof, of lightweight con­ sets of curves on graphs of sound pressure level zone system with supply and return fans. The crete on metal deck, is carried by 1211 deep versus octave band. meeting rooms use a multizone, constant trusses spanning from sidewall column to side­ Table 1 volume system with supply and return fans. The wall column. Their bottom chords support 4in office building uses a variable volume system. thick precast dense concrete ceiling panels. Performance Acoustical The mechanical tower is shown in Fig. 11 . space cr,/erion These trusses also support the lighting bridges Title 24 of The California Administrative Code and architectural ceiling, whose shape followed Audience and stage areas PNC-15 contains limits on the energy consumption of both acoustical and lighting considerations. Control rooms: audio PNC-20 Control room lighting and proJectlon RC-25 buildings and rules for calculation. This was not Steel pipes and angles and wooden panels are written with theatres in mind, and so interpre­ used in both bridges and ceiling panels. Orchestra pit PNC-15 Underseat storage areas PNC-20 tation is a matter of negotiation between the Lobby, meeting rooms, office block, Dressing rooms RC-30 designers and the plan checkers. It sets mini­ •nd mech•nlc•I tower Lobby areas RC-25 mum standards for wall and roof insulation, for The lobby is a steel-framed structure, at its lower Meeting room PNC-20 window insulation and shading coefficients. and levels engaging the auditorium, office building Kitchen RC-30 for equipment efficiencies. Arups calculated the and large meeting room. Above, it is approxi­ Administrative areas RC-35 annual energy consumption of the buildings mately 8011 square. Its perimeter moment frame Spaces opening onto stage and into house PNC-20 using industry-developed energy simulation is designed as a backup to the monumental software approved by the California Energy concrete stair which acts as a very stiff can­ Kirkegaard recommended, for acoustically Commission. tilevering shear wall - thus attracting most of sensitive spaces, low velocity, low pressure air. the lateral load in an earthquake. A two-way To deal with possible earthquakes. all distribution from remotely-located air handling mechanical equipment is seismically anchored. steel truss carries the roof. The moment-framed equipment. Constant volume systems were 6011 x 1Oft x 1Oft structure of the box office tower Some can simply be bolted down. Other equip­ preferred over variable volume. Ducts are lined ment, supported on vibration isolation, is re­ was fabricated in one piece off-site. It has a and provided with silencers. specially detailed sliding connection that per­ strained by devices that limit its travel when the mits earthquake-induced movement indepen­ The lowest level of the mechanical tower houses ground shakes (Fig . 12). Seismic anchorage of dent of the lobby in one direction while linking two centrifugal chillers, each with a cooling pipes and ducts is largely but not entirely them perpendicularly. capacity of 273 tons, specially modified to use covered by guidelines published by SMACNA ASHAAE Standard R-123 refrigerant. This is a (Sheet Metal and Air Conditioning Contractors The SOit-span steel roof trusses of the large chlorofluorocarbon. but with a hydrogen atom National Association) . Fig . 13 shows a typical meeting room are supported by perimeter shear replacing one of the fluorine or chlorine atoms duct seismic restraint, the design of which is walls of reinforced masonry. in its structure to make it less stable, so it will generally the responsibility of the mechanical The office block, like the large meeting room , break down in the lower atmosphere and not get subcontractor. At the seismic separations has reinforced masonry shear walls. Its sus· to the stratosphere. Chilled water is supplied at between buildings, special connections are pended floor and roof are steel-framed, with 44°F and returns at 56°F. The chillers are provided to allow substantial relative movement lightweight concrete on metal deck. served by two centrifugal counterflow cooling caused by earthquakes. 20 Cantilever arm guided by slot in seating tower Sound system terminal boxes Tower in Equipment base forward position 2in x 2 inx 16gauge ~ 2 in x 2 1nx ~ Ji vertical L-brace 16gauge ti ~ diagonal o E L·brace Electncal conduits ~ ~ run 1n top and bottom chords of cantilever ~ 8. arm ~ ~ •1, In machine "" bolt "' Floor or roof "' ; j------1 ,,.,,"'"' "' Towerm Anchor or r--·;::_-;_;-- :.,f'.; storage I L.J L.J / 1 expansion bolts positjon : r,c~~ir... , : ______J I ______L.J L.J L.J J I Sm

DuctStze

12. Vibration-isolated equipment 13. Typical bracing 14. Flexible conduits restrained by snubbers. for 28 in diameter and 36in diameter ducts. for power. sound and lighting to towers.

In California, detailed design of sprinklers is borative effort by Arups as electrical engineers Reference carried out by specially licensed contractors, and Theatre Projects as work, house and pro­ (1) REID , F. Municipal multi-form: Derngate Centre working to the designers' performance specifi­ duction lighting designers was required to Building Study. Architects ' Journal, 179(10), cation. Fire suppression and smoke extraction iterate the design towards compliance. pp.49-64 , 7 March 1984. of the stagehouse received a lot of attention from Power, sound and lighting for the moveable Credits the City Fire Marshall. The agreed scheme has Client: seating towers are supplied either via flexible City of Cerritos Redevelopment Agency gridiron level deluge sprinklers, low level, high conduits (Fig . 14) or by unplugging, moving the velocity horizontal throw sprinklers on opposite towers, and plugging in again. City Project Manager: sides of the stage, smoke extract vents in the Kurt Swanson flytower roof, and forced smoke extraction via Some theatrical productions generate smoke on Theatre manager: low level ductwork when the concert ceiling is stage, and to prevent that from activating the Phil! Lipman in place. smoke detectors at high level over the stage, Architect: there is a bypass switch, operated by the stage Barton Myers Associates Electrical systems manager, which shuts down the detectors for Structural, mechanical, electrical and The Arts Center receives a 4000A. 277/480V four hours. public health engineers: three-phase, four-wire service from the Emergency power is provided by a 400kW Ove Arup & Partners California Southern California Edison Company. The main generator. Theatre consultant: electrical room is at the lowest level of the Theatre Projects Consultants . Ughtlng design mechanical tower. acoustically isolated from the Acoustician: auditorium. From the main switchboard, power Theatre Projects and Barton Myers developed Kirkegaard & Associates the lighting concepts for the main public spaces, is distributed via transformers to two distribution Landscape architect: switchboards at 120/208V. The first switchboard whilst Arups incorporated the lighting within the Burton and Spitz total electrical design of the Arts Center. Many is in the main electrical room , the second on an Graphic/interior designer: isolated slab in the dimmer room of the theatre. of the public areas incorporate timers as part of April Greiman their lighting controls. The main circuit breakers are rated at 1600A Cost consultant: and 3000A respectively. Flexible connections In the theatre, lighting falls into four categories: Vermeulen and Logg limit noise transmission from the transformers. house, concert, stage and work lighting; all con­ General contractor: Panelboard locations were carefully chosen to trolled via 766 dimmer channels, all with full SAE/Continental Heller Construction meet the differing needs of architect and elec­ memory, from the main console at the rear and Project management consultants: trical engineer. from local panels around the stage and audi­ Stegeman and Kastner As with the mechanical systems, it was torium. The large meeting room has 60 control Photos: necessary for the electrical design to show channels for 192 dimmers. 15, 16: Barton Myers Associates compliance with the energy conservation Concluslon 17: Otto Jensen requirements of Title 24 . Based on work by the Construction is now well under way (Figs. 15, Drawings Illumination Engineering Society, Title 24 relates 16, 17). When complete, Cerritos will have a 1-4. 8: courtesy the architects allowable power consumption to functional world class, multi-use facility to mark another 5, 6, 9-1 4: Ove Arup & Partners categories and is very task-oriented. Theatrical stage in the city's development. 35 years ago As this project was designed in US units, lighting exists as much for art as for the carrying Cerritos was best known for its dairy farms: these have been retained here. out of tasks, and Title 24 thus is difficult to apply today it is for its regional shopping centre and 1 kip = 1000 lbf "' 4.45kN to theatres, with interpretation again negotiated auto sales. Soon it will be a centre of excellence by designers and plan checkers. A major calla- for the performing arts. 15. 16. 17. Cerritos Arts Centre under construction.

15. 16. 17.

21 DESIGN FOR HAZARD: FIRE Introduction Two of the papers already published in this series have dealt with wind and earthquake design. Both are specializations which have grown out of the basic language of structural engineering and as such needed only limited introduction. Fire engineering is a little different: an embryonic discipline beginning to have an Smoke spread as escape starts Further Sl)fead with t.me Last person out increasing impact on building design, 1. Stansted Airport: combined smoke spread and people movement modelling. drawing on a very broad base of engineering disciplines. the movement of people compared In order to illustrate the state-of-the­ Void to the flow of smoke. Fig. 1 shows art position, we have chosen to how people moving towards an exit discuss projects we have been might appear to an observer close to involved with which fall outside the the fire after two minutes. normal categorization of buildings Check in desks This was almost certainly the first and occupied structures as envisaged time that a CFO analysis had been in the Building Regulations. used in demonstrating fire safety in a Transport terminal buildings, with building, and with current advances potentially long escape routes in large in computing speed and graphic volume spaces, demand an under­ output this is a technique which has standing of fire development and Void Void enormous potential in the future. smoke spread in order to keep people safe as they move· away from Kansai Airport any fire incident before it is fought. 2. A simplified plan of Kansai airport check-in concourse. shaded areas A similar set of problems was tackled indicate heat flux >20 kWm2 assuming a fully developed fire in each area. in developing the fire safety strategy Offshore structures, particularly in for Kansai Airport, to be built in relation to the safe use of combus­ Osaka Bay in Japan. The issues are tible materials, require an under­ spaces. This removes the usual smoke layer. The use of this con­ protection of fire-resisting compart­ servative approach ensured that related to the fact that this is a huge standing of how to restrict fire growth uncompartmented space within which and keep operatives safe until a ment walls to limit fire and smoke smoke would be contained within a spread. In the event of fire, people limited area, even without fire­ people might be moving for many means of rescue arrives, possibly minutes whilst a fire was detected, after the fire is extinguished. may have to move long distances resisting walls. This was termed the across possibly unfamiliar territory in Cabin Concept. confirmed and evacuation took These situations need quantifiable order to reach a place of safety. In place. The fire safety strategy understanding of the physics of fire Outside the Cabins, an unsprinklered depends on the Cabin Concept and international terminal buildings the fire might occur in seating or in applied to the structure, service escape procedures may be com­ exploits the high roof space once systems and functional planning of passengers' baggage. The ceiling of again as an effective smoke reservoir. plicated by the need to maintain the the building is some 12m above the the buildings and installations landsidefairside boundaries, and the Attitudes of the regulatory authorities involved. They also require an floor and it was argued that this problems of communicating in foreign provides a reservoir to keep smoke vary, when presented with a fire understanding of human reactions, languages. However, on the positive safety strategy based on engineering pedestrian traffic engineering, and above head height in the event of a side, transport terminals are designed fire in the circulation or seating areas. calculations rather than on regulations. the pre-planned response of the specifically to promote a smooth flow The UK Building Regulations have a emergency services in order to of people. There tend to be open To study this in detail, a computational flexibility which allows this kind of complete equations of safety for spaces for circulation which are fluid dynamics (CFO) analysis was approach, though paradoxically this personnel and (where significant) largely free of combustible material. carried out to assess smoke flow does not always make the path of property. In addition there may be a high across the ceiling. This technique the negotiations smoother. In Japan, The essence is to quantify and make ceiling over all or much of the divides the three-dimensional space where the regulations are less flexible, sound engineering judgements about terminal which can act as a smoke under consideration into a large the building control authorities have the particular objectives of designing reservoir. number of cells. The mass, momen­ the option to set up a committee of tum , heat and turbulence conservation against the effects of fire. It may be It is the task of the fire safety experts if they feel that they are not surprising to realise that many of the equations are solved for each cell for in a position to judge the schemes engineer to exploit the positive each short time step. By considering fire safety-related aspects of the features of this kind of building and presented. Whilst this introduces an building regulations are subjective a fire suddenly starting at a given element of delay into the proceedings, to propose additional fire protection point in the building it is possible to and do not necessarily have an measures which will ensure that the prospect of negotiating on an engineered basis. As we continue to study the flow of smoke away from engineering level with this committee people are at no more risk in the that point as a function of time. develop our discipline, especially in proposed building than in one that has definite advantages. areas outside the scope of current can comply with the letter of the Calculations were additionally carried The Ministry of Construction in Japan regulations as described below, so regulations. out to assess how people might recently published a unique integrated we will be better able to influence on Stansted Airport evacuate the space, based on guide to fire protection. This a rational basis the design of all measured walking speeds as they addresses a wide range of issues buildings to make them safer. The recently opened new terminal building at Stansted Airport (see The moved through an airport baggage and provides calculation techniques Transport terminals Arup Journal, Spring 1990, pp.7-15) reclaim area. The average speeds, for the sorts of studies that are rele­ We have contributed fire safety provides a good example of how a around 1mfsec , were in accordance vant. The guide proposes design advice to a number of projects range of techniques may be brought with those quoted from a number of fires, sets alternative safety standards concerned with transport terminals. together to form a coherent fire studies elsewhere. The flow of people for escape routes, deals with smoke through the building exit doorways, These buildings have features in safety strategy. It was decided that flow, suggests how fire resistance of as a function of time after escape common, and the problems which people should be protected from the steel may be calculated, and so on. have to be tackled illustrate how an effects of a major fire as they made started, was estimated by assigning The document is comprehensive, integrated approach may be used to their escape, by fitting all the areas the measured distribution of speeds drawing on research work from all develop a soundly based strategy. A of high fire load (for example shops) to the maximum population within over the world and quoting all rele­ number of calculation techniques with a local roof to carry sprinklers the building. vant equations and sources. It points come into their own, both simple and a smoke extraction system. The By combining the smoke modelling the way to future developments in and sophisticated, and covering a required extract volume for smoke with the people flow modelling, it regulatory matters which will free the range of technical disciplines. was calculated using standard tech­ was possible to demonstrate that designer to adopt a range of In order to ensure the convenience niques based on the volume of air people would be able to move freely approaches to fire safety. It should of large numbers of people using a entrained into a hot plume, and over the escape period with large be said that the document has no terminal building, it is frequently assuming that all the heat from the margins of safety, with use made of legal status in Japan, but it was necessary to have very large public sprinklered fire goes into the hot graphic display techniques to visualize applied in developing the fire safety

22 Chris Barber, Paula Beever. Andrew Gardiner arguments for Kansai International parasol roof structure designed for Extra process safety equipment was Consequently, lire scenarios for the Airport, and its value in this was the extension to Marseilles Airport. In to be provided which would reduce inside and outside of the accom­ noted with interest by the authorities. both cases, the limited amount of the risk of secondary fires occurring. modation unit were developed, with and formed the basis for discussions combustible material in the building, The PLO was a three-level 'Armadillo' estimates made of the likely severity with the expert committee. together with the reserve strength in unit built up of repetitive modular and duration of each of the design In the negotiations, the committee the structure, allowed arguments to sections which were effectively cells fires. For internal fires it was found expressed concern that lire spread be made for leaving the steel bare. with plywood and timber framed that the plasterboard would prevent might occur across the circulation Offshore fire engineering walls, floors and roof. The plywood the timber from reaching its critical spaces and suggested that the Our first involvement in offshore lire panels were skinned internally with temperature of 250°C. No major absence of compartment walls engineering work arose indirectly plasterboard and externally with GRP. internal structural changes were required some other kind of additional from the Piper Alpha disaster, which The side of the PLO facing the oil necessary and only upgrading works protection. Estimates were made of occurred on the night of 6 July 1988 and gas process equipment, shielded to make good services, doors and the radiation from possible flames in when an explosion on !he platform by a 6mm steel plate cover, had a surface finishes were recommended. a fully developed lire in every corn· resulted in a fire that escalated to fire resistance of 60 minutes when For external fires the story was bustible area, assuming that the involve the main oil export line. 20 measured against the standard different. These included potential sprinkler system had failed. It was minutes after the initial incident a furnace test used to simulate a fi res from process equipment, crashed shown that each area was sufficiently second explosion in a gas pipeline cellulosic fi re. It was not designed to helicopters, refuelling tanks and from far from the next for the incident led to a massive intensification in the withstand a hydrocarbon fire, which diesel generator storage tanks. Flame radiation on fresh fuel to be too low fire. Of the 165 fatalities 79 occurred generates higher temperatures over sizes and shapes were estimated, (<20kW/m~ to cause ignition. This inside the accommodation unit where a shorter time period. Thermal shock taking into account the effects of became known as the Island Concept personnel had mustered. and greater heat fluxes had to be wind, and used to calculate heat (see Fig. 2). It was additionally shown The report from the public inquiry, accounted for when assessing fluxes onto the accommodation unit. that even ii passengers departed headed by Lord Cullen , took over passive fire protection. The worst fire considered had flames without their baggage, fire spread two years to complete and was The timber structure was clearly the impinging directly onto the PLO with across the space via the abandoned a temperature of 1000°C and a heat eventually published in November main problem for fires outside and 2 baggage would not occur. 1990. In the interim peri od offshore inside the PLO. It was concluded flux of 150kW/m . Fig. 3 shows Fire resistance operators questioned their safety that this should be fully protected some of the scenarios considered. Even at a relatively low calculated Large compartment sizes and long procedures and problems were from involvement in any likely lire. escape distances are not the only highlighted, particularly in relation to From experiment it was found that heat flux the plywood-GAP interlace issues which need to be addressed the use of living accommodation as the timber, with a fire retardant would exceed the critical temperature in terminal buildings. Architectural a place of safety. treatment, started to char and give of 250°C. Therefore it was necessary concerns are often of essential signi· off smoke at a temperature of to insulate the wood. Temporary safe refuge : A 20mm sprayed-on application of ficance in major public buildings. It is Heather 'A' PLO approximately 250°C. This was frequently desirable, for example, to chosen to be the maximum tempera­ intumescent to the outer skin with It was during this time that the Unocal suitable fixing details was evaluated maintain as a feature exposed struc­ Corporation approached us through ture that the wood could reach tural steelwork. It is then necessary before it was assumed to become as the most efficient solution to the Aberdeen office with the brief to protect the accommodation unit. The to consider the thermal response of investigate their existing Personnel involved in the lire. the steel under lire conditions and to weight and thickness of this material Living Quarters (PLO) on the Heather made it the most desirable and it had assess how that affects the structural Alpha platform. The aim was to response of the building as a whole. been tested against hydrocarbon protect personnel who had mustered fires. Thus, the existing structure was At Kansai Airport calculations on the inside the PLO for the duration of response of parts of the exposed maintained and a solution to any likely fire. Escape could then be upgrade the PLO to protect against steel structure to fire conditions were effected after the fi re if necessary. combined with structural calculations all credible fires was established. to show that structural collapse was Through negotiations with Lloyds not a safety problem. Similar calcu­ Register of Shipping, both the internal lations were carried out for the and external protection systems were proved with lull-scale panel tests. All PLO upgrade work has now been successfully completed. After we had carried out this work and other fi re engineering studies on platforms in the southern North Sea, the report by Lord Cullen into the Piper Alpha Disaster was published. In a wide-ranging review of the offshore industry's safety measures, Cullen recommended that existing fire regulations should be replaced by 'goal setting ' standards. His aim was to introduce engineered solutions to fire hazards by means of 'scenario-based design' so that an integrated approach to safety can be developed. We in the fire engineering team adopt this philosophy in all our projects both onshore and offshore. Summary This article has only touched on a few of the large number of major projects to which fire engineering techniques have been successfully applied in recent years. More and better tools are becoming available to us all the time. These, when coupled with more flexible attitudes on the part of regulatory authorities, may permit us to have an even greater influence on building designs 3. Some offshore lire scenarios. of the future.

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