Learning from Failure Long-Term Behaviour of Heavy Masonry Structures

Learning from Failure Long-term Behaviour of Heavy Masonry Structures

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Objectives

The field of architecture has experienced considerable advances in the last few years, many of them connected with new methods and processes, the development of faster and better computer systems and a new interest in our architectural heritage. It is to bring such advances to the attention of the international community that this book series has been established. The object of the series is to publish state-of-the- art information on architectural topics with particular reference to advances in new fields, such as virtual architecture, intelligent systems, novel structural forms, material technology and applications, restoration techniques, movable and lightweight structures, high rise buildings, architectural acoustics, leisure structures, intelligent buildings and other original developments. The Advances in Architecture series consists of a few volumes per year, each under the editorship - by invitation only - of an outstanding architect or researcher. This commitment is backed by an illustrious Editorial Board. Volumes in the Series cover areas of current interest or active research and include contributions by leaders in the field.

Managing Editor

F. Escrig Escuela de Arquitectura Universidad de Sevilla Spain

Honorary Editors

C. A. Brebbia P. R. Vazquez Wessex Institute of Technology Estudio de Arquitectura UK Mexico Associate Editors

C. Alessandri K. Ishii University of Ferrara Yokohama National University Italy Japan

F. Butera W. Jäger Politecnico di Milano Technical University of Dresden Italy Germany

J. Chilton M. Majowiecki University of Lincoln University of Bologna UK Italy

G. Croci S. Sánchez-Beitia University of Rome, La Sapienza University of the Basque Country Italy Spain

A. de Naeyer J. J. Sendra University of Ghent Universidad de Sevilla Belgium Spain

W. P. De Wilde M. Zador Free University of Brussel Technical University of Budapest Belgium Hungary

C. Gantes R. Zarnic National Technical University of Athens University of Ljubljana Greece Slovenia

K. Ghavami Pontificia Univ. Catolica, Rio de Janeiro Brazil

Learning from Failure Long-term Behaviour of Heavy Masonry Structures

Editor:

L. Binda Politecnico di Milano, Italy Editor: L. Binda Politecnico di Milano, Italy

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ISBN: 978-1-84564-057-6 ISSN: 1368-1435

Library of Congress Catalog Card Number: 2007922340

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Preface ...... xiii

Chapter 1 Failures due to long-term behaviour of heavy structures...... 1 L. Binda, A. Anzani & A. Saisi 1.1 Introduction ...... 1 1.2 The collapse of the Civic Tower of Pavia: search for the cause ...... 2 1.2.1 Description and historic evolution of the tower ...... 3 1.2.2 First experimental results and interpretation of the failure causes ...... 4 1.2.2.1 Structure and morphology of the walls...... 4 1.2.2.2 Geotechnical investigation...... 6 1.2.2.3 Physical, chemical and mechanical tests on the components ...... 7 1.2.2.4 Compression tests on masonry prisms...... 8 1.2.3 Long-term tests...... 9 1.2.3.1 Fatigue tests...... 9 1.2.3.2 Constant load tests ...... 11 1.3 Long-term behaviour of masonry structures...... 12 1.3.1 Deformation during mortar hardening...... 12 1.3.2 First, secondary and tertiary creep in rock and hardened masonry...... 15 1.4 Collapse and damage of towers due to long-term heavy loads...... 16 1.4.1 St. Marco bell-tower and St. Maria Magdalena tower in Goch ...... 16 1.4.2 The bell-tower of Monza Cathedral and the Torrazzo of Cremona ...... 16 1.5 The role of investigation on the interpretation of the damage causes...... 17 1.5.1 The bell-tower of the Cathedral of Monza ...... 18 1.5.2 The ‘Torrazzo’ of Cremona...... 21 1.6 Comparison between the two towers ...... 25 1.7 Conclusions ...... 26

Chapter 2 Experimental researches into long-term behaviour of historical masonry...... 29 A. Anzani, L. Binda & G. Mirabella Roberti 2.1 Introduction ...... 29 2.2 Tests on the masonry of the Civic Tower of Pavia ...... 31 2.2.1 Characterization by sonic tests ...... 33 2.2.2 Monotonic tests on prisms of different dimensions ...... 33 2.2.3 Fatigue tests...... 35 2.2.4 Creep tests on prisms of 300 × 300 × 510 mm...... 36 2.2.5 Pseudo-creep tests on prisms of 100 × 100 × 180 mm...... 39 2.2.6 Pseudo-creep tests on prisms of 200 × 200 × 350 mm...... 39 2.3 Tests on the masonry of the crypt of the Cathedral of Monza...... 42 2.3.1 Preparation of prisms of 200 × 200 × 350 mm...... 42 2.3.2 Characterization by sonic tests ...... 44 2.3.3 Monotonic tests...... 45 2.3.4 Fatigue tests...... 45 2.3.5 Creep test on one prism of 300 × 300 × 510 mm ...... 48 2.3.6 Pseudo-creep tests, first series...... 48 2.3.7 Pseudo-creep tests, second series ...... 50 2.4 Comments...... 52

Chapter 3 Collapse prediction and creep effects...... 57 P.B. Lourenço & J. Pina-Henriques 3.1 Introduction ...... 57 3.2 Short-term compression: failure analysis and collapse prediction using numerical simulations ...... 58 3.2.1 Experimental results...... 58 3.2.2 Continuum model...... 59 3.2.3 Particle model...... 62 3.2.4 Discussion of the results...... 63 3.3 Long-term compression: experimental assessment...... 66 3.3.1 Tested specimens...... 66 3.3.2 Standard compression tests...... 68 3.3.3 Short-term creep tests ...... 69 3.3.4 Long-term creep tests ...... 71 3.3.5 Discussion of the results...... 74 3.4 Conclusions and future work ...... 78 Chapter 4 Effects of creep on new masonry structures...... 83 N.G. Shrive & M.M. Reda Taha 4.1 Introduction ...... 83 4.2 The step-by-step in time approach to modeling time-dependent effects ...... 84 4.3 Case 1: An axially loaded column ...... 85 4.3.1 Creep model...... 85 4.3.2 Effect of coupling creep and damage in concentrically loaded columns...... 89 4.3.3 Examining the effect of rehabilitation...... 91 4.4 Case 2: Composite structural element subject to bending ...... 92 4.4.1 Development of model ...... 92 4.4.2 Application to a beam...... 97 4.4.3 Masonry walls subject to axial load and bending...... 103 4.5 New mathematical approaches to modeling creep...... 103 4.6 Discussion ...... 104 4.7 Conclusions ...... 105

Chapter 5 Experimental study on the damaged pillars of the Noto Cathedral ...... 109 A. Saisi, L. Binda, L. Cantini & C. Tedeschi 5.1 Introduction ...... 109 5.2 The collapse and the decision for reconstruction...... 109 5.3 On-site investigation on the remaining parts of the collapsed pillars...... 110 5.3.1 Layout of the section and of the masonry morphology...... 111 5.3.2 General characterisation of the materials ...... 111 5.3.3 Damage description...... 114 5.3.4 Laboratory testing...... 114 5.3.4.1 Mortars...... 115 5.3.4.2 Stones...... 115 5.3.4.3 Injectability tests...... 117 5.3.5 On-site tests...... 117 5.3.5.1 Flat-Jack tests...... 117 5.3.5.2 Application of sonic pulse velocity test to pillars...... 118 5.3.6 Design decisions...... 119 5.3.7 The dismantling of the remaining pillars...... 120 Chapter 6 Monitoring of long-term damage in long-span masonry constructions...... 125 P. Roca, G. Martínez, F. Casarin, C. Modena, P.P. Rossi, I. Rodríguez & A. Garay 6.1 Introduction ...... 125 6.2 Monitoring and long-term damage...... 125 6.3 Role of monitoring in the study of ancient constructions ...... 127 6.4 Monitoring: methodology and requirements...... 128 6.4.1 Technology ...... 128 6.4.2 Distinction between dynamic and static monitoring ...... 129 6.4.3 Requirements...... 131 6.5 Measuring damage and deformation related to historical or long-term processes ...... 133 6.5.1 Monitoring and long-term damage...... 133 6.5.2 Structural deformation...... 133 6.5.3 Tensile damage in arches and vaults ...... 135 6.5.4 Damage of compressed members...... 135 6.5.5 Fragmentation...... 139 6.6 Structural modelling and monitoring ...... 140 6.7 Case studies...... 141 6.7.1 Dynamic monitoring of Mallorca Cathedral ...... 141 6.7.2 S. Maria Assunta Cathedral, Reggio Emilia, Italy ...... 145 6.7.3 Vitoria Cathedral...... 148 6.8 Conclusions ...... 151

Chapter 7 Modelling of the long-term behaviour of historical masonry towers ...... 153 A. Taliercio & E. Papa 7.1 Introduction ...... 153 7.2 A continuum damage model for masonry creep ...... 154 7.2.1 Unidimensional viscoelastic model with damage ...... 154 7.2.2 Three-dimensional viscoelastic model with damage...... 157 7.2.3 Identification of the model parameters and comparisons with experimental results...... 160 7.3 Structural analyses of two masonry towers...... 166 7.3.1 The Civic Tower of Pavia...... 166 7.3.2 The bell-tower of Monza Cathedral...... 167 7.4 Remarks and future perspectives ...... 171 Chapter 8 Repair techniques and long-term damage of massive structures ...... 175 C. Modena & M.R. Valluzzi 8.1 Introduction ...... 175 8.2 The bed reinforcement technique...... 176 8.3 The experimental campaigns...... 178 8.3.1 Laboratory tests on the use of stainless steel bars ...... 179 8.3.2 Laboratory tests on the use of CFRP bars and thin strips...... 183 8.4 Case studies...... 197 8.4.1 The bell-tower of the Basilica of S. Giustina in Padua ...... 197 8.4.2 The pillars of S. Sofia church in Padua ...... 199 8.4.3 The bell-tower of S. Giovanni Battista Cathedral in Monza (Milan)...... 199 8.5 Final remarks...... 201

Chapter 9 Simple checks to prevent the collapse of heavy historical structures and residual life prevision through a probabilistic model ...... 205 L. Binda, A. Anzani & E. Garavaglia 9.1 Introduction ...... 205 9.2 The safety of ancient towers ...... 205 9.2.1 A survey on Italian cases...... 206 9.2.2 Comments on the observed crack patterns ...... 206 9.2.3 Elaboration of the collected data ...... 209 9.3 A probabilistic model for the assessment of historic buildings ...... 210 9.4 Fragility curves from the experimental data ...... 215 9.4.1 Fragility curve F versus σ applied to creep tests ...... 215 9.4.2 Comparison between vertical and horizontal strain-rate...... 215 9.4.3 Fragility curve F versus σ applied to pseudo-creep tests ...... 216 9.4.4 Comparison between vertical and horizontal strain-rate...... 218 9.5 Application to the bell-tower of Monza...... 219 9.6 Conclusions ...... 221

Conclusions...... 225

Preface

On March 17 1989, the Civic Tower of Pavia collapsed without any apparent warning signs – killing four people. Subsequently, L. Binda, together with four colleagues from DIS, Politecnico of Milan, was nominated a member of a Committee that had the aim of helping the Prosecutor of the Procura della Repubblica in Milan find the causes of the collapse. After an experimental and analytical investigation lasting nine months, the collapse cause was found. Progressive damage dating back many years, due mainly to the heavy dead load put on top of the existing medieval tower with the addition of a massive bell-tower in granite, was to blame. This type of long-term behaviour of masonry structures was not as well researched as it was for concrete and steel structures and for rocks. Experimental research aimed at showing the reliability of this interpretation was carried out, and is still continuing, that is more than sixteen years of research since 1989. After careful interpretation of the experimental results, also based on experiences from rock mechanics and concrete, the modelling of the phenomenon for massive structures, such as creep behaviour of masonry, was implemented by collaboration with E. Papa and A. Taliercio from the same department. Other case histories were collected such as the collapse of the Sancta Maria Magdalena bell-tower in 1992 in Dusseldorf, the damage to the bell-tower of the Monza Cathedral, Italy, and to the Torrazzo in Cremona, Italy. Later on, in 1996 the collapse of the Noto Cathedral, Italy, showed that similar progressive damage can take place in pillars of churches and cathedrals. Collaborations on the topic first started with the University of Padua (C. Modena) and later on with the University of Minho, Portugal (P. Lourenco). Then the University of Calgary, Canada (N. Shrive) and the University of Barcelona (P. Roca) were involved. The editor would like to thank the technicians Mr Antico, Mr Cucchi and Mr Iscandri for their collaboration in the experimental research and Mrs C. Arcadi for her help in the editing of the chapters.

The Editor 2007