Seismic Retrofit of Existing Reinforced Concrete Buildings E-Book

Stelios Antoniou

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 747

Veröffentlichungsjahr: 2023

Beschreibung

Seismic Retrofit of Existing Reinforced Concrete Buildings Understand the complexities and challenges of retrofitting building infrastructure Across the world, buildings are gradually becoming structurally unsound. Many were constructed before seismic load capacity was a mandatory component of building standards, and were often built with low-quality materials or using unsafe construction practices. Many more are simply aging, with materials degrading, and steel corroding. As a result, efforts are ongoing to retrofit existing structures, and to develop new techniques for assessing and enhancing seismic load capacity in order to create a safer building infrastructure worldwide. Seismic Retrofit of Existing Reinforced Concrete Buildings provides a thorough book-length discussion of these techniques and their applications. Balancing theory and practice, the book provides engineers with a broad base of knowledge from which to approach real-world seismic assessments and retrofitting projects. It incorporates knowledge and experience frequently omitted from the building design process for a fuller account of this critical engineering subfield. Seismic Retrofit of Existing Reinforced Concrete Buildings readers will also find: * Detailed treatment of each available strengthening technique, complete with advantages and disadvantages * In-depth guidelines to select a specific technique for a given building type and/or engineering scenario * Step-by-step guidance through the assessment/retrofitting process Seismic Retrofit of Existing Reinforced Concrete Buildings is an ideal reference for civil and structural engineering professionals and advanced students, particularly those working in seismically active areas.

Leseprobe

Seismic Retrofit of Existing Reinforced Concrete Buildings

Stelios Antoniou

Seismosoft ltd.

Pavia

Italy

This edition first published 2023© 2023 John Wiley & Sons Ltd

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The right of Stelios Antoniou be identified as the author of this work has been asserted in accordance with law.

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Library of Congress Cataloging‐in‐Publication Data is Applied for:

Hardback ISBN: 9781119987321

Cover Design: WileyCover Image: Courtesy of Dr. Stelios Antoniou

Dedication page

To Eleni, Lydia and Miley

Foreword by Rui Pinho

It is undeniable that seismic assessment and retrofitting of the existing building stock in many parts of the world has become the primary focus of structural engineers. The reasons behind this pressing need are multiple and multifaceted, as clearly explained and discussed in this book. However, the vast majority of currently active structural engineering practitioners did not receive any formal training on this particular topic, which only in recent years has started to find its way into the syllabus of civil engineering degrees. There is therefore a great need for seismic retrofitting guidance within the practicing community – guidance that should be not only of a conceptual and theoretical nature but also, or perhaps mainly, practice oriented.

This textbook addresses perfectly such undeniable need, as a result of the rather unique and special technical background of its author. Indeed, Dr. Stelios Antoniou combines an impeccable academic training in structural earthquake engineering, obtained from the National Technical University of Athens and from Imperial College London, with a two decades of hands‐on experience in the seismic assessment and retrofitting of existing structures (he is partner and technical director of a construction company specializing in this field, Alfakat) and with an equally long, accomplished career of developing earthquake engineering software tools that are employed by thousands of users around the globe (he is co‐founder and chief developer of Seismosoft).

It is therefore easy and immediate to appreciate how the present textbook will inevitably read very differently from other publications on the same topic, some of which I am co‐author of, which tend to feature a more academic and formal writing‐up and discussion, as opposed to the very practical and colloquial style adopted by Dr. Antoniou. The latter renders this volume not only extremely rich and informative in terms of contents and actual application, but also rather easy and pleasant to follow.

The book is logically organized in two main parts. The first of these introduces the current status quo on the common weaknesses found in existing reinforced concrete structures (Chapter 2), the methods available to gain knowledge on a building's properties and characteristics (Chapter 3), and the typical techniques at the disposal of practitioners to retrofit this type of structures (Chapter 4). Unlike other books, however, such overview is given and described with the assistance of several tens of photographs from actual buildings and retrofitting applications undertaken by Dr. Antoniou, which renders it truly unique and clear. This first part of the book is then closed by a precious section where the author provides his experienced insight on the type of criteria one should have in mind when selecting one retrofitting strategy over another (Chapter 5).

The second part of the book is instead fully focused on the procedure that practitioners need to follow in order to assess the seismic response of an existing reinforced concrete building and then define an appropriate and code‐compliant seismic retrofitting intervention. It thus naturally covers not only the selection of appropriate seismic performance targets (Chapter 6) and structural analysis techniques (Chapter 7), but also discusses advanced structural modeling issues (Chapter 8) and the necessary structural performance code‐compliance checks (Chapter 9). The manner in which these four steps can and should be brought together in the process of seismic assessment and retrofitting is illustrated by a start‐to‐finish application to an actual case‐study (Chapter 10), which perfectly leverages the very practical software tools developed by Dr. Antoniou.

In short, this is a volume that I believe all structural engineering practitioners, as well as students and academics, should have on their bookshelves, given not only the invaluable and unique insight that it provides on the type of challenges one is faced with when dealing with the seismic performance of existing reinforced concrete buildings, but also the very clear and practical guidance it conveys on how to potentially intervene in such structures.

Rui PinhoProfessor of Structural EngineeringUniversity of Pavia, Italy

Acknowledgments

Writing this book was harder than I initially thought, but more rewarding than I could have ever imagined. None of this would have been possible without so many supportive people in my life. I wish to express my sincere gratitude to all those who have directly or indirectly contributed to this endeavor. In particular, I would like to express my special thanks to:

Dr Rui Pinho for being a great friend and partner (in Seismosoft), for providing continuous support and unfailing assistance, and for inspiring me in many different ways. His contribution to my work has been invaluable, not least because he had the initial idea for this book back in the summer 2019.

Kostas Antoniou, who has been extremely helpful, supportive, and resilient throughout all this time. Apart from being my brother and a lifetime friend, he is a fantastic partner (in Alfakat), who keeps tidying up all the messes that I leave behind, when I move forward to the next “big” thing.

Zoe Gronti from Seismosoft and Giouli Liaskou from Alfakat, who made the initial reviews of the chapters and gave me extremely valuable first feedback on several aspects of the book.

My friends and colleagues in Seismosoft and Alfakat, who have contributed significantly to the book in many different ways. Special thanks to Dr Thanasis Farantos, Panagiotis Doulos, Thodoris Rakintzis, Evi Visviki, Thanasis Karatzas, Yiannis Spilios, Vaggelis Trikkas, Dr Fanis Moschas, Artan Xhemalallari, Apostolis Economou, George Kalfas, Nancy Gouma, Vassilis Samaras, Nikos Modes and Marios Basoukos.

Christos Giannelos and Christos Giarlelis for providing useful material and photographs, but more importantly for their constructive comments, which helped me in crystallizing several points I make throughout the book.

Odysseas Verroios, Nikos Zarkadoulas, George Kyriakou, Jose Poveda, and Christos Varelas for providing useful material and photographs.

Sara Kaufman for the corrections in the initial English text, but also for her insightful suggestions and positive comments.

My parents for their continued love, support, and patience, but also for their guidance and encouragement at the different stages of my academic and professional life.

Everyone on the Wiley team who helped in getting this book out in the market.

Last, but certainly not least, my family – and in particular, my wife, Eleni, and my daughter, Lydia, for their patience and understanding all this time, and more importantly, for making this life journey as good as it gets (and even better).

1Introduction

1.1 General

The vast majority of existing buildings, even in the most developed countries, have been built with older provisions, with low or no seismic specifications. As a result, their ability to withstand earthquake loads is considerably lower with respect to modern standards, and they suffer from significant irregularities in plan and/or elevation, low ductility, and low lateral strength and stiffness. They exhibit increased vulnerability to seismic loading and often have a critical need for strengthening.

Seismic assessment and strengthening is a promising field of civil engineering. It requires special knowledge and often poses great challenges to the engineer, both in the design and the construction phase of the strengthening interventions. Because many older structures are vulnerable to seismic activity, this constitutes an exciting new field of the construction industry that is far from saturated and is expected to gain importance and exhibit significant development in the years to come. This significance is highlighted by the publication of several documents and standards worldwide that are dedicated to this subject from organizations such as the American Society of Civil Engineers (ASCE), the Federal Emergency Management Agency (FEMA) in the United States, New Zealand Society for Earthquake Engineering (NZSEE) in New Zealand, the Earthquake Planning and Protection Organization (EPPO) in Greece, The European Committee for Standardization in the EU, and other regulatory agencies in Europe.

The documents and standards provided by these agencies include ASCE 41 (ASCE 2017) and its predecessors FEMA 273 (FEMA 1997) and FEMA 356 (FEMA 2000) in the United States, Eurocode 8, Part 3, in Europe (CEN 2005), NZSEE in New Zealand (2017), KANEPE (2022) in Greece, and large dedicated chapters in NTC‐18 (NTC 2018) in Italy and the Turkey Building Earthquake Regulation (TBDY 2018) in Turkey.

The main incentive for writing this book has been the realization that, despite the importance of the subject and the publication of thousands of papers on the strengthening of existing structures, there are very few complete books or reports with specific guidelines on the strategy for structural retrofit. This book attempts to provide structural engineers a thorough insight on seismic assessment and strengthening, specifically for existing reinforced concrete buildings, providing information on available strengthening techniques and on the methodologies and procedures that should be followed to assess an existing or strengthened structure. More importantly, it gives detailed directives on the strategy for the strengthening interventions – that is, which method(s) to use, when, how, and why.

This chapter provides a brief introduction on the main international and national standards employed for the seismic evaluation and strengthening of existing structures. The remaining book is divided in two parts.

In the first part (Chapters 2–5), issues of a more practical nature will be discussed, as well as all the field works related to structural assessment and strengthening. In Chapter 2, the main problems affecting existing reinforced concrete (RC) buildings are described, such as bad detailing, poor workmanship, corrosion, and bad construction practices. In Chapter 3, the challenges of monitoring RC buildings are explained, and the methods for the measurement of the required structural quantities, and the nondestructive and destructive testing involved are presented. In Chapter 4, the available strengthening techniques for the retrofit of a reinforced concrete building are described in detail, and the most important design and construction issues related to them are discussed, together with their main advantages and disadvantages. A simple example with the seismic retrofit of an existing building with the most important techniques is also presented. Finally, in Chapter 5 the criteria for selecting the most appropriate strengthening method and the basic principles of conceptual design are discussed, and more than 15 actual case studies from practical applications of the retrofit of existing buildings are presented, explaining in each case which strengthening method was selected and why.

The second part (Chapters 6–10) constitutes a detailed description of the code‐based seismic assessment and retrofit procedures, which should be followed for the structural upgrading of existing RC buildings. In Chapter 6 the performance levels, the limit states, the seismic hazard levels, and the performance objectives are explained, and a detailed discussion is given on how to make an appropriate selection of performance objective. In Chapter 7 the linear and nonlinear methods for structural analysis are presented, and in Chapter 8 general issues on the modeling of reinforced concrete structures are discussed, with a particular focus on the modeling for nonlinear analysis. Chapter 9 describes the main safety verification checks that are performed in a structural evaluation methodology, while in Chapter 10 an application example of the structural evaluation and strengthening of an existing reinforced concrete building is presented, following all the steps of the procedure: selection of performance and seismic hazard levels, modeling, structural analysis and safety verifications.