Engineering History and Heritage Structures – Viewpoints and Approaches

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Engineering History and Heritage Structural Engineering Documents 15 Structures – Viewpoints and Approaches Structures –Viewpoints Structural EngineeringDocuments International AssociationforBridgeandStructural Engineering(IABSE) Engineering History and Approaches and Heritage Eugen Brühwiler Eberhard Pelke 15 005/12/17 2:44PM 5 / 1 2 / 1 7

2 : 4 4

P M Structural Engineering Documents About the Authors Objective: To provide in-depth information to practicing stuctural Eberhard Pelke earned his civil engineer diploma engineers in reports of high scientifi c and technical standards on a wide range of structural engineering topics. from Darmstadt University. He is Head of the Department of Bridge Engineering at Hessen Mobil IABSE Bulletin Board: Road and Traffi c Management in Wiesbaden, H.Subbarao, (Chair), D. Laefer, (Vice Chair), M. Bakhoum, Germany. He is a Fellow of IABSE and was from C. Bob, M.W. Braestrup, N.P. Hoej, H.H. Snijder, R.von Wölfel, 2013-17 Chair of IABSE WG9 Construction R. Mor, M.G. Bruschi, I. Payá-Zaforteza, S. Kite, M. Garlock. History. Topics: The International Association for Bridge and Structural Engineering (IABSE) operates on a worldwide basis, with interests of all type of structures, in all materials. Its members represent structural engineers, employed in design, Eugen Brühwiler is professor of structural engi- academe, construction, regulation and renewal. IABSE organises conferences and publishes the quarterly journal neering at the EPFL—Swiss Federal Institute Structural Engineering International (SEI), as well as reports of Technology in Lausanne, Switzerland. His and monographs, including the SED series, and presents activities include modern methods to examine annual awards for achievements in structural engineering. and enhance structures of high cultural value. With a membership of some 4,000 individuals in more than He is a Fellow of IABSE and was from 2013-17 100 countries, IABSE is the international organisation for structural engineering. Vice-Chair of IABSE WG9 Construction History. Publisher: The International Association for Bridge and Structural Engineering (IABSE) was founded as a non-profi t scientifi c association in 1929. Today it has more than 3000 members in over 100 countries.IABSE’s mission is to promote the exchange of knowledge and to advance the practice of structural engineering worldwide. IABSE organizes conferences and publishes the quarterly journal Structural Engineering International, as well as conference reports and other With Contributions From: monographs, including the SED series. IABSE also presents annual awards for achievements in structural engineering. E. Pelke, T.F. Peters, M. Traykova, R. Vergoossen. A. Bögle, W. Lorenz, E. Brühwiler, N. Janberg, J. Romo, B. Addis, M.J. Beiersdorf, J. Steiner, E. Vianen, R. Spaan, For further Information: J.F. Duntemann, B.R. Greve, A. Traykov, D. Partov, N. Winterbottom, B. Heres, T. Chardakova, D. Wendland, P. van Bogaert, R. Barthel, J. Tutsch, J. Jordan, C. Weber, IABSE c/o ETH Zürich A. Kostka, M. Fischer, G. Eisele, J. Seiler, V. Wetzk, Y. Rammer, B. Espion, L. Clarke, CH-8049 Zürich, Switzerland M. Bartzsch, K. Geißler, D. Gasparini, W. Vermes, J. Voermans, R. May, Y. Yang, Phone: Int. + 41-44-633 2647 B. Chen, S. Nakamura. Fax: Int. + 41-44-633 1241 E-mail: [email protected] Web: www.iabse.org

All rights reserved. No part of this book may be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the publisher. ISBN 978-3-85748-154-3

Publisher: IABSE c/o ETH Zürich CH-8049 Zürich, Switzerland

Phone: Int. + 41-44-633 2647 Fax: Int. + 41-44-633 1241 E-mail: [email protected] Web: www.iabse.org

SED15_title-page.indd 2 04/12/17 8:40 PM Preface

Foreword

The roots of modern construction historiography reach back to the 19th century when for exam- ple in France the engineer Auguste Choisy (1841–1909) began to explicitly analyze the construction of historic buildings and to place them in the center of construction history. 1 In the last third of the 20th century, such approaches followed systematically and in an increasingly professional way. A long arch spans from the works like those by Jacques Heyman (1925) who interpreted ancient techniques and theories related to vaults by means of modern structural engineering approaches,2 to the historic–theoretical research and publications like those by Karl- Eugen Kurrer (1952).3

In the meantime, several chairs and professorships in construction history were created and there is an impressive variety of conferences and publications. Every three years since 2003, the scientifi c community gathers at the International Congress on Construction History (ICCH). There is no doubt that construction history has established and consolidated internationally as an independent discipline.

Actually, what is construction history? Professor Werner Lorenz, member of the IABSE WG9 Construction History, defi nes construction history as follows:

Structural engineering is the entity of the practices and products of conceptual design, dimen- sioning and construction of technical structures and components in the process of the con- structional designing of the environment. Construction history describes and interprets these practices and products in their historic sequence. For that purpose, construction history inter- rogates the products of construction and all associated written and pictorial sources. Both the historic construction research and the methods of static-constructive and scientifi c engineering analyses belong to the methodical cornerstones.

Construction history involves architects, monument conservators, historians and engineers in a transdisciplinary approach to fulfi ll scientifi c, cultural, didactic and also structural engineering tasks and requirements.4 PREFACE

IABSE WG9 Construction History has the general objective to promote this new science and to demonstrate its importance for structural engineers. The three main objectives of the WG on construction history are to:

• increase awareness among structural engineers of historical and cultural aspects of structures and structural engineering; • illustrate and propagate the social and technical achievements of civil engineering; • improve methods and practice in structural engineering by showing ways for systematic and targeted integration of historical and cultural aspects in intervention projects to adapt or modify structures of cultural value for future demands.

IABSE WG9 focuses on the role of construction history in the structural engineering practice and is thus intentionally complementary to the classical construction history as understood by the ICCH Community. The main concern of WG9 is thus to implement construction history in the daily work of structural engineers and to demonstrate the importance of cultural values as a basic design parameter when interventions on existing structures are required.

The present Structural Engineering Document (SED) is structured accordingly. It shall be understood as an introduction into construction history and how to consider the cultural values of structures in intervention projects. Although this SED is addressed primarily to IABSE structural engineers, it may also be useful for nonengineers.

This SED begins with the Editorial written by one of the “deans” of construction history: Tom F. Peters. Personal statements by several WG9 members testify a surprising variety of ways how the access to construction history was found and how it infl uenced professional activities. In the next chapter, Nicolas Janberg provides a worldwide survey on the activities and contacts in the domain of construction history. In the following, the papers by Max Johann Beiersdorf and Josef Steiner are contributions similar to essays on the aspects of construction history.

Twenty-fi ve case studies on rehabilitation and modifi cation of structures form the core material of this SED. Every case study outlines on a maximum of four pages the cultural values of the structure and highlights the appropriate measures for its respectful preservation. References and contact data of the author serve the reader to obtain detailed information. The case studies obviously range from ancient to modern structures and from medium to high cultural values, comprising various types of structures. Requirements of cultural heritage shall be taken as inspiration (and no longer as “hindering constraint”) for better intervention projects on existing structures. Construction history and cultural values of structures have yet to be understood as basic structural engineering disciplines.

With the present SED, the IABSE WG Construction History intends to make a signifi cant con- tribution to modern structural engineering and to provide access to construction history for practicing structural engineers. References

[1] Choisy A. L’art de bâtir chez les Romains Ducher: Paris, 1873. [2] Heyman J. Coulomb’s Memoir on Statics: An Essay in the History of Civil Engineering Cambridge University Press: Cambridge, 1972. REFERENCES

[3] Kurrer K-E. The History of the Theory of Structures Ernst & Sohn: Berlin, 2008. [4] Kurrer K-E. Aufgaben der Bautechnikgeschichte. https://gesellschaft.bautechnikgeschichte. org/was-ist-bautechnikgeschichte/ Download 01.01.2017.

Eberhard Pelke, Chairman of IABSE Working Group 9 Construction History August, 2017

Table of Contents

1 History as Educator and as an Aid to Understanding Structural Engineering; T.F. Peters 1

2 Personal Statements by Members of IABSE WG9 Construction History: What is Construction History and Why is It Signiﬁ cant for Structural Engineers? 7 Eberhard Pelke 7 Marina Traykova 8 Rob Vergoossen 9 Annette Bögle 10 Werner Lorenz 11 Eugen Brühwiler 12 Nicolas Janberg 13 Jose Romo 15 Ignacio Paya-Zaforteza 15 Bill Addis 16 References 19

3 Engineering History and Heritage Structures around the World—A Survey; N. Janberg 21 Introduction 21 Survey 21 Current Situation of Construction History around the World 22 Overall Evaluation and Summary 38 References 39

4 (Re)constructing History—How Building Archaeology Can Proﬁ t from the Knowledge of Engineering; M.J. Beiersdorf 41 Introduction 41 Undulating Mud Brick Walls in Pharaonic Egypt 42 Engineering Science Studies 44 Building Archaeology and Construction History— A Fruitful Cooperation 44 References 45

SED_15-1TOC.indd 1 04/12/17 8:50 PM 5 The Many Footprints Left by Martin Bachmann in Pergamon; J. Steiner 47 Dedication 47 Building Z on Pergamon’s Acropolis Hill 47 Repair and Conversion of the Southern Rotunda Next to the Red Hall 49 Assembly of a Monumental Supporting Figure Next to the Red Hall 51 Maintenance of Retaining Walls on the Acropolis Hill 51 Anastylosis of a Palaestra Corner in the Gymnasium 52 Final Remarks 53 References 53

6 Buildings 55

6.1 The Building A of Radio Kootwijk—A Concrete Building from 1920, Ready for the Future; E. Vianen, R. Spaan 55

6.2 Marina City—The History and Restoration of an Iconic Facade; J.F. Duntemann, B.R.Greve 61

6.3 Rehabilitation of the Complex Reinforced Concrete Shell Roof Structure of an Industrial Building; A. Traykov 67

6.4 Maintenance and Strengthening of the Timber Roof Elements in the Church of St. Dimitar; M. Traykova, D. Partov 71

6.5 Brighton Pier, UK—Innovation in Renovation; N. Winterbottom 77

6.6 Early Iron Structures at the Hermitage in St. Petersburg—Unique Testimonies to Construction History and the Associated Preservation Problems; B.Heres 83

6.7 Maintenance and Strengthening of the Cross-Shaped Barracks Building; M. Traykova, T. Chardakova 89

6.8 Analytical and Experimental Studies on the Technology of Late-Gothic Vault Construction; D. Wendland 95

6.9 Frost Damage and Restoration of Limestone Domes and Spheres in a Heritage Building; P.V. Bogaert 101

6.10 The Gothic Tower of Freiburg Minster, Germany: Analysis and Repair; R. Barthel, J. Tutsch, J. Jordan 107

6.11 The Municipal Public Bath at Strasbourg (1905Ð1908): A Cultural Heritage in Reinforced Concrete; C. Weber, A. Kostka 113

6.12 History and Rehabilitation of Reinforced Brick Ceiling; M. Fischer 119

6.13 Reconstruction of the Neues Museum in Berlin; G. Eisele, J. Seiler 125

SED_15-1TOC.indd 2 04/12/17 8:50 PM 101

Chapter 6.9 Frost Damage and Restoration of Limestone Domes and Spheres in a Heritage Building

Philippe Van Bogaert, Prof., PhD; Ghent University, Ghent, Belgium

Introduction

Domes and spheres have been used extensively in heritage buildings during baroque and rococo periods as well as in 19th-century buildings. Used as ornaments and as coverings and roofs, these curved elements add to the monumental character of imposing buildings, which are presently considered a part of the cultural heritage. The number of historic buildings containing domes and spheres is impressive and includes some of the world’s most famous structures. Most of these ornaments and coverings are made of limestone because of its excellent quality and durability. However, because limestone is a sedimentary rock, consisting mainly of calcium carbonate, it may deteriorate due to acid rain and frost. The latter introduces cracking, allowing water ingress and subsequent further cracking. Depending on the crack width, further mois- ture ingress is fostered, and cracks grow. In the present paper, this progressive effect is being assessed by numerical simulation. Obviously, all types of limestone blocks and ornaments are prone to degradation due to frost. However, a brief survey of various degradations shows that curved shapes are more vulnerable. The reason for this is yet to be found. The ratio of exposed surface to volume of a sphere is not signifi cantly different from the value for an equivalent cube. However, if rainfall is considered from a single direction, for instance, vertical, the relative exposure ratio of spheres is three times larger than that of cubes. This might give some indica- tion of the larger degradation of curved surfaces. Southern Pressure House, Antwerp

The Southern Pressure House, in Antwerp, consists mainly of two long buildings, the fi rst of which contains the machine room and the steam hall and parallel storage depots for coal and oil.1 The boiler room and the warehouses are separated by a corridor that opens to a court- yard. The second building houses offi ces, homes for personnel, a repair workshop and a forgery house. Of all these, the imposing unit containing the accumulators for water pressure (Fig. 1) is the most valuable. This is mainly a brickwork building decorated with limestone façade blocks, 102 CHAPTER 6.9. FROST DAMAGE AND RESTORATION OF LIMESTONE DOMES AND SPHERES

which were intended to enhance the view as the city particularly wished to improve the appearance of the neighborhood.

The front view of the building clearly shows the two vertical parts containing the water accumulators. The entrance door and ground level appear rather massive; the twin columns are richly decorated, suggesting the cylindrical accumulators inside, and the narrow openings underline the vertical orientation of the building. Both towers are covered by domes carved from single limestone blocks. An individ- ual dome is shown in Fig. 2. The domes are supported by white sandstone cylindrical masonry. The total height of the structure reaches 24.5 m. Figure 2 also shows some of the heavy cornices, column capitals and decorating spheres. The highly decorated industrial building was highly appreciated in the second half of 19th century and dis- plays the wealth and prosperity of the port Figure 1 Southern Pressure House: front view of Antwerp in industrial times. The style of this building may appear to be excessively heavy, but the exterior form clearly shows the particular purpose of the building. In addition, the domes entirely correspond to the inside equipment.

Although the installation was decommis- sioned in 1977, the whole complex was listed as protected heritage in 1979. About 20 years back, a complete restoration was undertaken, and the buildings became a center for performing arts. This lasted until fi ve years ago when the theatre com- pany ceased to exist. Since then, events are being organized in the 4000 m2 building Figure 2 Top of the vertical part with the dome with its seven rooms, except for the front unit (Fig. 1) which remains unused. The activities include seminars, smaller concerts, receptions, discussions and workshops, as well as art studios. During the inspection of the heritage building in January 2012, several limestone ornaments and blocks were found to be heavily cracked. In addition, during the 1985 restoration, inferior products were used at some locations. After some of the limestone debris fell, a second inspection was organized in December 2012. As both inspections were conducted in winter, it was hoped that frost was at maximum and recent degradation would be detected. Cracks reached SIMULATION OF DOME CRACKING 103

a width of 10 mm, and some parts needed immediate removal as there was a threat of debris falling on to the footpath below. The inspections also showed that some parts of the structure were already missing. These fi ndings have urged the owners to apply for necessary funding for a restoration program and to install safety measures in order to avoid endangering passers-by below the building. However, the larg- est concern applies to the domes as these also suffer from cracking. Figure 3 shows a detail of the cracked state of the domes. Fig. 3: Degradation of the dome It is clearly seen that the limestone surface is eroded in horizontal layers. This seems to be characteristic of domes and spheres. Simulation of Dome Cracking

The domes are relatively small and consist of hemispheres with an inner radius 1.22 m and an outer radius 1.40 m, the thickness being 0.18 m. The base of the dome consists of a fl at ring with an outer radius of 1.63 m, thus providing a larger support and stiffening the dome. The idea was to constitute a model of volume elements and to introduce cracking as soon as tensile stresses exceed the tensile strength of the limestone. The tensile strength value of 5.67 MPa is considered rather low, far below the average compression strength of 140 MPa or a characteristic value of 126 MPa. This type of approximation allows reasonable assessment of the infl u- ence of cracks on dome resistance. In further steps, nonlinear material characteristics may be considered, although it is believed this will not consistently modify the results. The approach consists of introducing cracks into the model, assuming subsequent water ingress and allowing the effect of frost. The latter will start the progressive effect, the issue being how far this process may continue and eventually lead to the destruction of the dome.

Modeling of the effects of frost proved to be delicate. A fi rst approach considers that an initial crack is completely fi lled with water. As the water freezes, its volume increases by 9%, thus causing an internal pressure in the crack. This internal pressure needs to be applied to the crack surface. The main issue is to identify the magnitude of the pressure. This, and other approaches based on the Washburn equation,2 all disregard the actual process of freezing in natural stone. The latter has been researched more extensively in Ref. [3]. Although the research is considered to be idealized, it enumerates the various phenomena involved during freezing. The model is based on the importance of the fl ow of water toward the solidifi cation front of ice, as well as on the existence of thin fi lms separating the ice and the surrounding stone, as mentioned earlier. The thickness of these fi lms varies from 15 to 30 Å. These fi lms also exert an attractive force on the pore water and a disjoining pressure that pushes the ice and the stone apart, which is the pressure we are seeking. The fastest damage growth rate occurs in the range from −4 to −15°C.

In Ref. [3], the case of a spherical cavity has been studied using the Gibbs–Duhem equation to describe the change from liquid to solid state, the van der Waals interactions and the Clau- 104 CHAPTER 6.9. FROST DAMAGE AND RESTORATION OF LIMESTONE DOMES AND SPHERES

Fig. 4: Cracking of the dome wall

5 sius–Clapeyron equation. The porosity of the

4 stone has been taken into account, and three στ examples have been worked out. It appears 3 σχ Stress (MPa) that dense rock-like granite can certainly 2 crack due to freezing water as the pressure 1 crack depth (mm) rises up to 25 atm or 2.533 MPa. However, 0 –10 10 30 50 70 90 110 130 150 in the case of sandstone, in a spherical cavity, –1 pressure would rise to 12 atm or 1.22 MPa, –2 and this value also corresponds to limestone. –3 In porous stone, the main pressure rise is due to the pre-melting stage when the ice is very Fig. 5: Evolution of stresses with crack depth close to the stone. The fl ow then reverses, and the water fl ows toward the solidifi cation front. This explains why the pressure rises suffi ciently to cause cracking only in the case of very impermeable rock. Consequently, the research in Ref. [3] has been adopted for the present simu- lations. The pressure in a spherical cavity is most probably higher than that in a longitudinal crack, which has a larger surface area in contact with air. Consequently, an internal pressure of 1.22 MPa has been applied to a crack on the outer surface of the dome. This crack runs along a quarter of the circumference of the dome, its depth being increased stepwise. Looking at a cross- section of the dome, the local meridian stresses can be found as shown in Fig. 4 for crack depths of 1/20, ¼ and ½ of the dome thickness.

The former cracks have been assumed to exist before water ingress and freezing. The stresses shown in Fig. 4 may either cause excessive tensile stress at the crack tip or may crush the crack opening at the surface. In addition, the crack may be widened due to internal pressure. In all of these cases, the crack will increase until these quantities decrease below a critical level. The diagram in Fig. 5 summarizes the tensile and compression stresses as a function of the crack depth. The upper blue line shows the tensile stresses, which in all cases is below the tensile strength of 5.67 MPa. This simply implies that the cracks will not increase due to frost, and there is no progressive deterioration. This also applies to the compression stress, which is two to three times lower than the tensile stress. According to these results, water ingress and subsequent frost cannot be responsible for damage to the domes. In addition, the evolution of crack width with the depth has been summarized in the graph in Fig. 6. This illustration also shows that the crack width is moderate. Hence, the model has indicated that cracking of the limestone CONCLUSIONS 105

0.3 crack width (mm) 0.25

0.2

0.15

0.1

0.05 crack depth (mm) 0 –10 10 30 50 70 90 110 130 150

Fig. 6: Evolution of crack width with depth Fig. 7: Developed crack ornaments is probably not due to freezing of water in the cracks. Calculations were continued until 80% of the dome wall thickness was cracked, and yet no progressive effect was seen. At this particular point, the crack width grows to about 0.3 mm. When all loads are considered, the dome still remains stable. The deformations at this stage are shown in Fig. 7, the crack opening being clearly visible, including the effect at the tip inside the stone. In view of these results, the crack length has not been varied, nor has the exact location been modifi ed, and further analysis becomes irrelevant. Restoration

As the present state of deterioration of the domes and other limestone parts of the Southern Pres- sure House in Antwerp cannot be due to frost, the cause must reside in chemical attack due to increase of CO2, thus favouring the dissolution of the material. Due to the nature of limestone, the calcium carbonate may dissolve if the pH of rainwater is suffi ciently low because of CO2 content. Therefore, refurbishment should preferably make use of soft lime mortar to close the surface cracking. Deeper and larger cracks, endangering further decay and disintegration of the parts, may be treated by injection of epoxy-based products. Former calculations have shown that injection pressure may easily reach 5 bars (0.5 MPa). However, these epoxy-based products are harmful to the limestone as they have little permeability and can become rather rigid in the stone. Hence, they should be used in-depth only and after the surface treatment of cracks with lime cement is complete. After successive inspections and temporary measures to avoid accidents, the restoration of the Pressure House is presently being considered. The project will require more extensive evaluation of the various repair methods. However, it may have become clear that water ingress and frost are not the main reasons for the degradation. Conclusions

Recent inspections have revealed that important limestone parts of the Southern Pressure House, a heritage building in Antwerp, show large cracking and may fall from the building. Water ingress and frost are thought to be the cause. The domes show horizontal cracks that might be of particular concern during future restoration. An extensive numerical model has been used to 106 CHAPTER 6.9. FROST DAMAGE AND RESTORATION OF LIMESTONE DOMES AND SPHERES predict cracking due to frost. Various approaches to model the effect of water ingress and frost have been considered. Among these, the approach based on the successive stages during ice growth, the presence of a water fi lm separating ice from the surrounding stone and the internal water fl ow toward the ice front seems the most successful. Application of this approach clearly shows that the effect of frost is incapable of fostering progressive cracking as both the tensile stress at the crack tip and the compression stress at the surface are suffi ciently small. In addition, crack width may increase with depth, and this quantity also remains small.

References

[1] Himler A. The Southern Pressure House and 7 other hydraulic stations” (in Dutch). Monu- menten en Landschappen 1985; 4(6): 8–28. [2] Fisher L. An experimental study of the Washburn equation for liquid fl ow in very fine capil- laries. J. Colloid Interface Sci. 1979; 69(3): 486–492. [3] Vlahou I, & Worster M. Ice growth in a spherical cavity of a porous medium. J. Glaciol. 2010; 56(196): 271–277.