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Recent major earthquakes around the world have shown the vulnerability of
infrastructure and the need for research to better understand the nature of seismic
events and their effects on structures. As a result, earthquake engineering research has
been expanding as more and more data become available from a large array of seismic
instruments, large scale experiments and numerical simulations. This book presents
results from some of the current seismic research activities including threedimensional
wave propagation in different soil media, seismic loss assessment,
geotechnical problems including soil-structure interaction, and seismic response of
structural components and structures including historical and monumental structures,
bridge embankments, and different types of bridges and bearings.
First part of the book deals with seismic risk assessment and hazard analysis with a concentration on seismic microzonation, development of probabilistic hazard maps, geotechnical problems including soil-structure interaction, and three-dimensional
wave propagation in different soil media considering different surface characteristics and topography. Chapter 1 provides a methodology for seismic risk assessment within
a performance based earthquake engineering framework. Probabilistic hazard analysis and economic models are used for loss estimation and evaluation of earthquake impact on regional economies. Chapter 2 describes development of seismic
microzonation and probabilistic hazard maps for a specific region. Details of site characteristics including geological conditions and soil nonlinearity were considered
in the seismic zoning and hazard assessment. Chapter 3 presents cognitive methods for modeling geotechnical and seismological problems. New data-driven modern techniques are used to complement and improve the traditional physically-based
geotechnical modeling and system analysis under earthquake loading.

Bridge Under Seismic Loads Discussion of results

The response quantities obtained from both the response-spectrum analysis and the timehistory analysis included bending moments, shear forces, axial forces, and displacements. A detailed review of the response results showed that the observations from the shear forces and the axial forces were the same as those from the bending moments. Given this, only the bending moments and the displacements  Full Article…

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Bridge Under Seismic Loads Conclusions

The objective of this study was to investigate the performance of the Confederation Bridge due to seismic excitations expected at the bridge location. A finite element model of a typical segment of the bridge was subjected to selected seismic motions representative of the seismic hazard for the bridge location. The response results obtained from the dynamic analysis of the  Full Article…

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Bridge Under Seismic Loads Dynamic analysis and results

For the purpose of the seismic evaluation of the bridge, dynamic analyses were conducted on the bridge model to determine the responses due to seismic actions represented by the uniform hazard spectrum and the selected sets of records. Elastic material properties of the model were assumed in the analyses. The dynamic analyses included both responsespectrum analyses and time-history analyses.  Full Article…

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Seismic excitations for time-history analysis

Given the uncertainties in the estimation of the seismic hazard for eastern Canada, a number of time-history analyses were conducted using excitation motions well beyond the scenario earthquake motions for the bridge location determined from the seismic hazard analysis as discussed in Section 3.3. In total, five groups of different seismic excitations were considered. Because of lack of strong  Full Article…

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Modelling of the bridge

The structural system of the bridge allows the development of a model of a selected segment of the bridge rather than modelling the entire bridge. Because of the repetitiveness of the units of the structural system (i.e., portal frames and drop-in girders) along the bridge, a proper model of a selected segment would be quite representative of the whole  Full Article…

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Scenario earthquakes for the bridge location

The seismic hazard at a given site represents the sum of the hazard contributions of different earthquakes at different distances from the site. For each site, however, there are a few earthquakes that have dominant contributions to the hazard. These earthquakes are normally referred to as scenario or predominant earthquakes. The shape of the uniform hazard spectrum for  Full Article…

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Seismic hazard for the bridge location

Since the development of the design parameters for the Confederation Bridge in early 1990s, there have been significant advances in the understanding of the seismic hazard in Canada. New source models, and most updated software have been used for the assessment of the seismic hazard. It should be mentioned, however, that there are still significant uncertainties in the  Full Article…

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Seismic design parameters

The design life of 100 years and the safety index of 4.0 were the basic design requirements for the Confederation Bridge. These requirements were much higher than those prescribed in the highway bridge design codes available at the time when the bridge was designed. The specified design life and safety index for the Confederation Bridge required special studies in  Full Article…

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Description of the bridge

The Confederation Bridge consists of two approach bridges at its ends and a main bridge between them (Fig. 1). The approach bridge at the Prince Edward Island end (i.e., the east end) is 555 m long and has 7 piers, and that at the New Brunswick end (i.e., the west end) is 1,275 m long and has 14  Full Article…

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Seismic Risk Summary and conclusions

This document describes the authors’ efforts in addressing the technical component of embankment prioritization, and is well suited to a reliability-based model for seismic risk assessment. A methodology is presented to quickly conduct seismic assessment and ranking of bridge embankments in order to identify and prioritize those embankments that are highly susceptible to failure. The step-by-step methodology is provided  Full Article…

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Category identification, ranking, and prioritization of the I-24 bridge embankments in Western Kentucky

In the KESR model, three categories are sought out to specify the failure risk of each embankment during a designated seismic event. A category for each bridge embankment along I-24 in western Kentucky is assigned. The assigned category is based on the three ranking parameters: the (C/D)min. ratio, the embankment displacement, and the liquefaction potential. Definition of the three  Full Article…

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Vulnerability analysis of I-24 bridge embankment in Kentucky

For a bridge on or over I-24 in western Kentucky, the potential of an embankment slope to displace during a designated earthquake event is assessed using the two-dimensional limit equilibrium stability analysis. During the seismic vulnerability evaluation of each embankment, the possibility of occurrence of either circular or wedge–shaped slope failure [11] is investigated and the one that results  Full Article…

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Seismic Risk Embankment properties

The geometry of each bridge embankment on or over I-24 in western Kentucky is taken from the bridge plans. The geometry of the 127 studied embankments is classified into five types (Figure 5a-5e). An embankment has either a single slope or double slopes separated by a perm. The inventory of I-24 bridge embankments in western Kentucky shows that a  Full Article…

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