Seismic Design and Assessment of Bridges

Inelastic Methods of Analysis and Case Studies

herausgegeben von: Andreas J. Kappos, M. Saiid Saiidi, M. Nuray Aydınoğlu, Tatjana Isaković

Verlag: Springer Netherlands

Buchreihe : Geotechnical, Geological and Earthquake Engineering

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

The book focuses on the use of inelastic analysis methods for the seismic assessment and design of bridges, for which the work carried out so far, albeit interesting and useful, is nevertheless clearly less than that for buildings. Although some valuable literature on the subject is currently available, the most advanced inelastic analysis methods that emerged during the last decade are currently found only in the specialised research-oriented literature, such as technical journals and conference proceedings.

Hence the key objective of this book is two-fold, first to present all important methods belonging to the aforementioned category in a uniform and sufficient for their understanding and implementation length, and to provide also a critical perspective on them by including selected case-studies wherein more than one methods are applied to a specific bridge and by offering some critical comments on the limitations of the individual methods and on their relative efficiency.

The book should be a valuable tool for both researchers and practicing engineers dealing with seismic design and assessment of bridges, by both making the methods and the analytical tools available for their implementation, and by assisting them to select the method that best suits the individual bridge projects that each engineer and/or researcher faces.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract

Modern codes for seismic design of buildings, bridges, and other civil engineering structures offer to the designer the choice between elastic and inelastic analysis methods, i.e. ‘Traditional’ methods wherein design is based on the results of a series of elastic analyses that provide linear action effects (moments, shears, axial loads) which are reduced by a global force reduction factor (q-factor in Europe, R-factor in the US) that depends on the overall ductility and overstrength capacity of the structure. Displacement and/or deformation based methods, wherein inelastic deformation demands in the structure are estimated for a given level of the earthquake action (typically expressed in terms of the displacement of a control point of the structure) with the aid of a series of inelastic (i.e. material nonlinear) analyses of either the static or dynamic type. These demands are then checked against the corresponding deformation capacities of the critical structural elements.

Andreas J. Kappos

Chapter 2. Modelling of Bridges for Inelastic Analysis

Abstract

The analytical tools necessary for the implementation of inelastic methods for bridges are presented. The chapter starts with available models for the bridge deck and their role in seismic assessment, addressing not only elastic modelling of the deck but also far less explored issues like the verification of deck deformation demands in cases that inelastic behaviour of the deck is unavoidable. Then the topic of modelling bearings and shear keys is presented, which is of paramount importance in the case of bridges, logically followed by the related issue of seismic isolation and energy dissipation devices; modelling of all commonly used isolation and dissipation devices is discussed and practical guidance is provided. The next section is devoted to inelastic modelling of different types of bridge piers, which are the bridge components wherein seismic energy dissipation takes place in non-isolated structures. All types of inelastic models for members, with emphasis on reinforced concrete columns, are presented in a rather detailed way, including both lumped plasticity and distributed plasticity models. Several examples of application of the previously mentioned models to bridges of varying complexity are provided and critically discussed. The last two sections of the chapter deal with modelling of the foundation of bridges and its interaction with the ground. Simple and more sophisticated models for abutments and (surface and deep) foundation members are provided, followed by models for the surrounding ground, with emphasis on the embankments that often play a crucial role in the seismic response of bridges, in particular short ones. Soil-structure interaction modelling of bridges is presented in both its commonly used forms, i.e. linear, as well as nonlinear soil-foundation-bridge interaction analysis in the time domain. These last sections of the chapter also include a brief overview of the characteristics of seismic ground motion which is used as input for the analysis.

M. Saiid Saiidi, Antonio Arêde, Donatello Cardone, Pedro Delgado, Mauro Dolce, Matej Fischinger, Tatjana Isaković, Stavroula Pantazopoulou, Gokhan Pekcan, Rui Pinho, Anastasios Sextos

Chapter 3. Methods for Inelastic Analysis of Bridges

Abstract

The chapter presents in a uniform way the available inelastic analysis methods for the seismic assessment and design of bridges. Since inelastic response-history analysis has long been used for bridges without substantial changes or developments during the last decade, it is presented in a rather brief and concise manner, leaving aside details of the numerical integration of the equations of motion that can be easily found in structural dynamics textbooks. On the contrary, inelastic static (pushover) methods, which have been the focus of extensive research in the recent years, particularly in the direction of extending them to structures with significant higher mode effects (a typical example being the transverse direction of many bridge types), occupy the largest part of the chapter. The methods described do not encompass all variations of pushover analysis techniques that deal with approximate ways for treating higher mode effects; instead, only those methods that have been specifically applied (after proper tailoring) to bridges have been selected. The different methods are presented not in a strict chronological order, but by classifying them into ‘single-mode’ and ‘multi-mode’ pushover analysis procedures. In the first category the now well-known N2 method is described in sufficient length as a typical representative. Within the ‘multi-mode’ pushover category a distinction is made between procedures involving a series of individual-independent modal pushover analyses (among which the modal pushover analysis technique adapted to the needs of bridges is presented in detail) multi-mode procedures based on adaptive incremental implementation of response spectrum analysis for simultaneous modal pushover analyses (the IRSA method is described in detail), and multi-mode procedures based on single-run pushover analysis with modal-combined adaptive seismic load or displacement patterns (the ‘Adaptive Capacity Spectrum Method’ is presented as the most recent version of this approach) For all major approaches to pushover analysis, an effort is made to describe them in such detail that would permit their implementation by the reader, provided, of course, that he/she has the appropriate analytical tools (cf. Ch. 2) and the expertise to use them. Practical application is also facilitated considerably by the information provided in the next chapter.

M. Nuray Aydınoğlu, Matej Fischinger, Tatjana Isaković, Andreas J. Kappos, Rui Pinho

Chapter 4. Case Studies and Comparative Evaluation of Methods

Abstract

The methods presented in chapter 3 are applied here to specific case-studies, involving bridges with different length and configuration. The chapter starts with a critical discussion of the basic parameters that influence the applicability of pushover methods. Then, a number of case-studies are presented in a rather uniform and detailed way; they were selected among those available with a view to including at least one application of each category of methods described in the previous chapter and (wherever feasible) to applying two or more ‘simplified’ methods to the same bridge structure. In addition to a number of pushover analyses, all case-studies include also response-history analysis of the inelastic response of the bridge, which serves as a reference for evaluating the results of the various approximate (static) procedures. In the case studies, in addition to the four pushover methods described in detail in Chapter 3, some other variants of the key approaches are also used and comparatively evaluated, so that at the end a more global picture of practically all analysis and assessment techniques available for bridges is provided. To allow for an even broader view on the issues involved and put the purely analytical methods into the proper perspective, the final section of chapter 4 presents an experimental evaluation of analytical methods, i.e. results from analytical methods (response-history, as well as pushover) are compared with those from the shaking table testing (using three shaking tables) of a 1:4 scale bridge model.

Tatjana Isaković, Antonio Arêde, Donatello Cardone, Pedro Delgado, Matej Fischinger, Andreas J. Kappos, Nelson V. Pouca, Rui Pinho, Anastasios Sextos

Chapter 5. Conclusions and Recommendations

Abstract

The key conclusions regarding the range of applicability and the relative performance of the analytical assessment methods presented in the book are summarised, and some specific recommendations are made regarding the selection of analytical model and analysis method in a practical context.

Andreas J. Kappos, Tatjana Isaković

Backmatter

Titel: Seismic Design and Assessment of Bridges
herausgegeben von: Andreas J. Kappos
M. Saiid Saiidi
M. Nuray Aydınoğlu
Tatjana Isaković
Verlag: Springer Netherlands
Electronic ISBN: 978-94-007-3943-7
Print ISBN: 978-94-007-3942-0
DOI: https://doi.org/10.1007/978-94-007-3943-7