Seismic response of skewed RC box-girder bridges

Abstract

It is critical to ensure the functionality of highway bridges after earthquakes to provide access to important facilities. Since the 1971 San Fernando earthquake, there has been a better understanding of the seismic performance of bridges. Nonetheless, there are no detailed guidelines addressing the performance of skewed highway bridges. Several parameters affect the response of skewed highway bridges under both service and seismic loads which makes their behavior complex. Therefore, there is a need for more research to study the effect of skew angle and other related factors on the performance of highway bridges. This paper examines the seismic performance of a three-span continuous concrete box girder bridge with skew angles from 0 to 60 degrees, analytically. Finite element (FE) and simplifi ed beam-stick (BS) models of the bridge were developed using SAP2000. Different types of analysis were considered on both models such as: nonlinear static pushover, and linear and nonlinear time history analyses. A comparison was conducted between FE and BS, different skew angles, abutment support conditions, and time history and pushover analysis. It is shown that the BS model has the capability to capture the coupling due to skew and the signifi cant modes for moderate skew angles. Boundary conditions and pushover load profi le are determined to have a major effect on pushover analysis. Pushover analysis may be used to predict the maximum deformation and hinge formation adequately.

Effect of Skew Angle on Seismic Vulnerability of Rc Box-Girder Highway Bridges

“…It is noted that no signi¯cant e®ect of orientation of excitation with respect to the skew angle is expected based on the recent study by Abdel-Mohti and Pekcan. 1 To conduct the incremental dynamic analyses described earlier, each ground motion pair was scaled to PGAs of 0.1 to 1.0 g with increments of 0.1 g. It is noted that the stronger components were scaled to the target level¯rst and weak components were scaled by the same respective scale factor. Therefore, a total of 1,350 nonlinear time history analyses were conducted using SAP2000 version 12.…”

“…The development of the fragility curves followed the procedure described in Eq. (1). It is noted that in general if the structural capacity and seismic demand are random variables that conform to either a normal or log-normal distribution then composite performance outcome is log-normally distributed.…”

“…Many researchers have investigated various aspects of the seismic response of highway bridges with signi¯cant skew. 1,2,34,45 It is agreed that the skew angle is crucial to the increase of the seismic vulnerability. In general, vulnerability analysis is an essential component of an overall seismic risk assessment (SRA) and loss estimation investigation for highway bridges.…”

Analytical and simplified models for dynamic analysis of short skew bridges under moving loads

“…Despite its simplicity, the stick model can provide reasonably good approximations for the preliminary assessment. More sophisticated 3D models using the shell and beam elements are also proposed to study this subject [6,12,9,13,14,15]. Regarding the behavior of the skew bridges under the traffic loads, the most of the work about this subject has been performed on the FE models using the combination of shell and beam elements and assisted by experimental testing [16,17,18,19,20,21].…”

A Finite Segment Method for Skewed Box Girder Analysis

“…During the past few decades, experimental and computational studies of skewed highway bridges have been performed [3][4][5][6]. Scordelis et al [7] presented the theoretical and experimental results of a 45 ∘ skew two-span four-cell reinforced concrete box girder bridge model with a 1 : 2.82 scale.…”