Table Of Contenti
Seismic Analysis and
Design using the
Endurance Time Method
ii
Taylor and Francis Series in Resilience and Sustainability in Civil,
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Seismic Analysis and Design using the Endurance Time Method
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Seismic Analysis and
Design using the
Endurance Time Method
Second Edition
Edited by
Homayoon E. Estekanchi and Hassan A. Vafai
iv
Second edition published 2022
by CRC Press
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and by CRC Press
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© 2022 selection and editorial matter, Homayoon E. Estekanchi and Hassan A. Vafai; individual chapters,
the contributors
First edition published by Momentum Press 2018.
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Library of Congress Cataloging-in-Publication Data
Names: Estekanchi, Homayoon E., editor. | Vafai, Hassan A., editor.
Title: Seismic analysis and design using the endurance time method /
edited by Homayoon E. Estekanchi and Hassan A. Vafai.
Description: Second edition. | Boca Raton, FL: CRC Press, 2022. |
Series: Resilience and sustainability | Includes index.
Identifiers: LCCN 2021020844 (print) | LCCN 2021020845 (ebook) |
ISBN 9781032108636 (hbk) | ISBN 9781032108698 (pbk) |
ISBN 9781003217473 (ebk)
Subjects: LCSH: Earthquake resistant design. | Failure time data analysis.
Classification: LCC TA658.44 .S3583 2022 (print) |
LCC TA658.44 (ebook) | DDC 624.1/762--dc23
LC record available at https://lccn.loc.gov/2021020844
LC ebook record available at https://lccn.loc.gov/2021020845
ISBN: 978- 1- 032- 10863- 6 (hbk)
ISBN: 978- 1- 032- 10869- 8 (pbk)
ISBN: 978- 1- 003- 21747- 3 (ebk)
DOI: 10.1201/ 9781003217473
Typeset in Times
by Newgen Publishing UK
v
Contents
Foreword ...................................................................................................................ix
Preface .......................................................................................................................xi
Biographies .............................................................................................................xiii
Chapter 1 Introduction to the Endurance Time Method .......................................1
1.1 Introduction ................................................................................1
1.2 The Endurance Time Concept ....................................................2
1.3 Endurance Time Excitation Functions .......................................4
1.3.1 Generation of Intensifying Accelerograms...................5
1.4 Analysis Method ........................................................................8
1.5 Endurance Criteria ...................................................................10
1.6 Application of Intensifying Excitation to Linear
SDOF Systems .........................................................................10
1.7 Application to MDOF Systems ................................................15
1.8 Summary and Conclusions ......................................................19
Chapter 2 Properties of the Endurance Time Excitation Functions ....................23
2.1 Introduction ..............................................................................23
2.2 Second Generation of ET Acceleration Functions ...................24
2.3 Comparison of ET Response Spectrum with a Real
Earthquake ...............................................................................25
2.4 Basic Ground- motion Properties ..............................................25
2.5 Frequency Content ...................................................................28
2.6 Power Spectral Density ............................................................29
2.7 Other Ground- motion Parameters ............................................30
2.7.1 Energy Parameters ......................................................31
2.8 Intensity Parameters .................................................................32
2.9 Period Parameters ....................................................................35
2.10 Peak Velocity Acceleration Ratio .............................................36
2.11 Cumulative Absolute Velocity ..................................................36
2.12 Sustained Maximum Acceleration (SMA) and
Velocity (SMV) ........................................................................37
2.13 Effective Design Acceleration (EDA) ......................................37
2.14 Summary and Conclusions ......................................................38
Chapter 3 Duration Properties of the Endurance Time Excitation
Functions ............................................................................................41
3.1 Introduction ..............................................................................41
3.2 Ground Motion Selection .........................................................42
3.3 ET Excitation Functions ..........................................................42
v
vi
vi Contents
3.4 A Review of Definitions of Strong- Motion Duration ..............44
3.5 Comparison between ET Accelerograms and Real Ground
Motions ....................................................................................47
3.6 Evaluation of Proposed Target Time ........................................47
3.7 Summary and Conclusions ......................................................52
Chapter 4 Generating ET Excitation Functions by Numerical
Optimization .......................................................................................55
4.1 Introduction ..............................................................................55
4.2 Generating ET Acceleration Functions ....................................56
4.3 Nonlinear Least Squares Formulation .....................................60
4.4 Improved ET Acceleration Functions ......................................63
4.5 Optimization of Long Duration ET Acceleration
Functions ..................................................................................64
4.6 Comparison of ETEFs in the Analysis of SDOF
Systems ....................................................................................68
4.7 Summary and Conclusions ......................................................73
4.8 Nomenclature ...........................................................................74
Chapter 5 Correlating Analysis Time with Intensity Indicators ..........................77
5.1 Introduction ..............................................................................77
5.2 Endurance Time Method ..........................................................78
5.3 Multiple Intensity Levels in the Performance- based
Design ......................................................................................80
5.4 Correlation between Time in ET Analysis and
Return Period ...........................................................................81
5.5 Explanatory Case Study ...........................................................89
5.6 Summary and Conclusions ......................................................92
5.7 Nomenclature ...........................................................................93
Chapter 6 ET Analysis of Framed Structures......................................................97
6.1 Introduction ..............................................................................97
6.2 Procedure for Application of the ET Method ..........................99
6.3 Specifications of Models, Ground Motions,
and Acceleration Functions ....................................................101
6.4 Comparison with Nonlinear Response History
Analysis ..................................................................................105
6.5 Application of the ET Method in Seismic
Rehabilitation of Buildings ....................................................117
6.6 Summary and Conclusions ....................................................119
Chapter 7 Multicomponent Endurance Time Analysis .....................................123
7.1 Introduction ............................................................................123
7.2 Review of Code Provisions and Related Research ................124
vii
Contents vii
7.3 Adaptation of the Endurance Time Method ...........................125
7.3.1 The Basic Concepts from the ET Method ................125
7.4 Characteristics of ET Acceleration Functions
Used in This Study .................................................................127
7.5 Comparison of ET Method with
Conventional Approaches ......................................................127
7.6 Structural Models ...................................................................129
7.7 Selection of Reference Ground Motions ................................129
7.8 Multicomponent Analysis ......................................................132
7.8.1 Scaling Procedure .....................................................132
7.8.2 Multicomponent Analysis by the ET Method ..........133
7.9 Summary and Conclusions ....................................................146
7.10 Nomenclature .........................................................................147
Chapter 8 Performance- based Design with the Endurance Time Method ........151
8.1 Introduction ............................................................................151
8.2 Concepts from the Endurance Time Method .........................153
8.3 Performance Levels ................................................................155
8.4 Target and Performance Curves .............................................156
8.5 Definition and Application of Damage Levels .......................159
8.6 Structural Model Frames Design ...........................................161
8.7 Presentation of the Analysis Results ......................................161
8.8 Summary and Conclusions ....................................................166
8.9 Nomenclature .........................................................................167
Chapter 9 Value- based Seismic Design with ET ..............................................169
9.1 Introduction ............................................................................169
9.2 Background ............................................................................171
9.3 Application of the Endurance Time Method ..........................173
9.4 Prescriptive Seismic Design ...................................................174
9.5 Performance- based Design ....................................................176
9.6 Value- based Design ................................................................181
9.6.1 Initial Costs ..............................................................182
9.6.2 Life- Cycle Cost ........................................................183
9.7 Comparative Study .................................................................188
9.8 Summary and Conclusions ....................................................188
9.9 Nomenclature .........................................................................192
Chapter 10 Seismic- Resilient Design by ET ......................................................197
10.1 Introduction ............................................................................197
10.2 Earthquakes and Resiliency ...................................................199
10.3 Concepts of Endurance Time Method ....................................199
10.4 Value- based Seismic Design by the ET Method ....................202
10.5 Case Study: Three- Story Steel Moment Frame .....................205
viii
viii Contents
10.6 Quantification of Resilience ...................................................206
10.7 Summary and Conclusions ....................................................210
Chapter 11 Sample Engineering Application: EDR Seismic Performance.........213
11.1 Introduction ............................................................................213
11.2 Basic Concepts from the Endurance Time Method ...............215
11.3 Modeling the EDR Device in OpenSees ................................220
11.4 Performance Assessment of EDR Devices by
ET method ..............................................................................221
11.5 Comparative Study .................................................................234
11.6 Summary and Conclusions ....................................................236
Index ......................................................................................................................239
ix
Foreword
I am delighted to write the Foreword for the second edition of this book, which
captures the recent advances on fundamentals of the “Endurance Time” method-
ology and its application to earthquake-r esisting design of structures. Protection of
buildings against earthquakes is of critical importance for seismic regions. In the con-
ventional aseismic design, the structure is strengthened to sustain the expected earth-
quake ground shaking without failure and/o r major damages. However, observations
of structural failures during earthquakes revealed that most destruction occurs as a
result of the gradual increase of damages and weakening of the building due to the
earthquake- induced loads. In this book, a new innovative method for performance
analysis of buildings to earthquake strong motion is presented. In this approach, the
structure is subjected to a seismic excitation with an intensity that increases with
time. The building damages are monitored until the collapse of the structure, and the
corresponding Endurance Time is evaluated. The Endurance Time method provides
a new realistic approach for the aseismic design of complex structural systems. The
second edition revised, updated, and enhanced the materials in the first edition.
In my view, the authors of this book are the pioneering experts in this area and
have been the developer of the Endurance Time methodology from its inception to
formalizing its applications to the earthquake-r esisting design of structures. I believe
this book provides the readers with an in- depth understanding of the Endurance
Time methodology for the aseismic design of buildings. The challenge that has
been presented to the authors has been to introduce the fundamental aspect of the
Endurance Time concept in a single textbook and bring it all the way to the actual
design of buildings. The authors can be proud that they have managed to achieve such
a task seamlessly. The description of the fundamentals of Endurance Time meth-
odology is broken down to easy-t o- understand exposition, beginning from the first
principals and building up towards a thorough description of the method targeted for
application to seismic response analysis of structures and evaluation of the associated
damages. More importantly, the authors have provided useful best- practice solution
methods that are accompanied by a practical approach in aseismic building designs.
Whether readers view this text from either the fundamentals of Endurance Time
methodology or the earthquake engineering side, the book provides readers with a
clear understanding of the comprehensive treatment of the structural responses with
the innovative approach of Endurance Time methodology for designing buildings
against earthquakes. This book is certainly an enthusiastic celebration of three basic
elements – theory, modeling, and practice – in handling a multitude of structural
design issues under earthquake excitations.
Goodarz Ahmadi
Clarkson University
Potsdam, New York
ix
