Table Of ContentThe Restoration of Ghirlandina Tower
in Modena and the Assessment of
Soil–Structure Interaction by Means of
Dynamic Identification Techniques
Built Heritage and Geotechnics
Series editor: Renato Lancellotta
Volume 1
ISSN: 2640-026X
eISSN: 2640-0278
The Restoration of Ghirlandina
Tower in Modena and the
Assessment of Soil–Structure
Interaction by Means of Dynamic
Identification Techniques
Rossella Cadignani
Former Director of Historical and Monumental
Building Division, Municipality of Modena, Italy
Renato Lancellotta
Former Professor of Geotechnical Engineering,
Politecnico di Torino, Italy
Donato Sabia
Associate Professor of Structural Engineering,
Politecnico di Torino, Italy
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Published by: CRC Press/Balkema
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DOI: https://doi.org/10.1201/9780429197789
Contents
Preface vi
About the authors viii
Acknowledgments ix
1 Introduction 1
2 Historical notes on the construction of the cathedral and
Ghirlandina Tower 5
3 Previous restoration work: Ancient modifications and 1970s’
interventions 35
4 Planning new investigation studies and restoration works 48
5 Soil as “material with memory”: A key to explain settlements
of the tower and the cathedral 78
6 A primer on soil–structure interaction and soil condition effects 95
7 Dynamic identification analyses: An approach to assess the real
behavior of structures 109
References 131
Appendix: Introductory notes on the leaning instability
of historic towers 136
Index 143
Preface
This is the first of a series of volumes on Built Heritage and Geotechnics, intended to reach
a wide audience: professionals and academics in the fields of civil engineering, architecture
and cultural resources management and particularly those involved in art history, history of
architecture, geotechnical engineering, structural engineering, archaeology, restoration and
cultural heritage management and even the wider public.
Motivations rely on the fact that the preservation of built heritage is one of the most
challenging problems facing modern civilization. It involves in inextricable patterns various
cultural, humanistic, social, technical and economic aspects. The complexity of the topic is
such that a shared framework of reference is still lacking among art historians, architects,
structural and geotechnical engineers. This is proved by the fact that, although there are
exemplary cases of an integral saving of any structural components with its static and archi-
tectural function, as a material witness of the knowledge, the culture and the construction
techniques of the original historical period, there are still examples of uncritical confidence
in modern technology which leads to the replacement of previous structures with new ones,
which only preserve an iconic appearance of the original monument.
For these reasons publishing short books on specialized topics, like well-documented case
studies of restoration work at one specific site or of a monument or detailed overviews of con-
struction techniques, intended as a material witness of knowledge of the historical period in which
the monuments were built, or specific conservation/preservation works, may be of great value.
The present volume, titled The Restoration of Ghirlandina Tower in Modena and the
Assessment of Soil–Structure Interaction by Means of Dynamic Identification Techniques,
provides within a single volume essential information on the history of the construction,
the involved techniques, previous interventions and restoration work. It is proved how the
interaction with the supporting soil may have had an important role because it explains the
meaning of the corrections that masons did during construction, the pattern of settlements
suffered by the tower and the cathedral and their interaction.
It is also discussed at length how the behavior of the tower during seismic events depends
on the interaction with the supporting soil because such interaction influences both the seis-
mic demand and the capacity of the system, and in this respect, this volume highlights the
benefit derived by using identification techniques to capture and forecast this behavior.
In addition to the previously mentioned motivations, a single aspect should capture the
interest of a wide readership: The cathedral and the Ghirlandina Tower were included in
1997 in the UNESCO World Heritage List, and it was recognized that
[t]he creation process shared by Lanfranco and Wiligelmo is a masterpiece of human
creativity, in which new dialectical relation between architecture and sculpture was
Preface vii
created in Romanesque art. The Modena complex bears exceptional witness to the cul-
tural traditions of the XII century in northern Italy’s urban society where its organ-
ization, religious character, beliefs, and values are all reflected in the history of the
buildings.
The series editor
Renato Lancellotta
About the authors
Rossella Cadignani graduated in Architecture at the University of Florence (Italy). She
worked in the municipality of Modena as Director of the Urban Development Planning
area and later on of the Historical and Monumental Building Division. She assumed
responsibility for the restoration work of Ghirlandina Tower and was a member of the
Technical Committee of Modena UNESCO site. At present she is working as a freelance
professional and is involved in historical research on the architecture of her city.
Renato Lancellotta was formerly Professor of Geotechnical Engineering at Politecnico di
Torino (Italy) and is Chairman of the Committee on Preservation of Monuments and
Historic Sites of the International Society of Soil Mechanics and Geotechnical Engineer-
ing. Professional experience refers to geotechnical studies for the preservation of built
heritage, including the Leaning Tower of Pisa and the Shroud Chapel in Torino. He was
a member of the Scientific Committee for the preservation of the Ghirlandina Tower and
the Cathedral of Modena, the Santo Stefano complex of churches in Bologna, and the
Giotto bell tower in Florence. He is also author of Geotechnical Engineering (Taylor &
Francis, 2009).
Donato Sabia is Associate Professor of Structural Engineering at the Politecnico di Torino
and is Head of the Materials and Structures Lab of the Department of Structural, Building
and Geotechnical Engineering. His research is related to structural diagnosis, experimen-
tal modal analysis and dynamics identification of linear and nonlinear systems and seis-
mic vulnerability of structures with special emphasis on masonry structures. He has been
involved in dynamic identification studies of the Ghirlandina Tower and the Cathedral of
Modena. He is a member of the Scientific Committee of the UNESCO site of Modena
and of the Commission of the Opera Primaziale di Pisa to monitor the leaning behavior
of Pisa Tower after the stabilizing interventions.
Acknowledgments
The authors are indebted to Dr Eng Renato Maria Cosentini for his assistance in preparing
the ground response analyses and related figures in Chapter 7, and to Dr Veronica Padovani
for providing the English version of Chapters 2, 3 and 4.
