• Steel and Composite Structures
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• v.32 no.3
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• pp.325-336
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• 2019

Concrete placement and temporary formwork of bridge deck overhangs result in unbalanced eccentric loads that cause exterior girders to rotate during construction. These construction loads affect the global and local stability of the girders and produce permanent girder rotation after construction. In addition to construction loads, the skew angle of the bridge also contributes to girder rotation. To prevent rotation (in both skewed and non-skewed bridges), a number of techniques have been suggested to temporarily brace the girders using transverse tie bars connecting the top flanges and embedded in the deck, temporary horizontal and diagonal steel pipes placed between the webs of the exterior and first interior girders, and permanent cross frames. This study includes a rigorous three-dimensional finite element analysis to evaluate the effectiveness of several bracing systems for non-skewed and several skewed bridges. In this paper, skew angles of $0^{\circ}$, $20^{\circ}$, $30^{\circ}$, and $45^{\circ}$ were considered for single- and three-span bridges. The results showed that permanent cross frames worked well for all bridges, whereas temporary measures have limited application depending on the skew angle of the bridge.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.5
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• pp.301-310
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• 2016

There are differences in seismic behavior between non-skewed bridges and skewed bridges due to in-plane rotations caused by pounding between the skewed deck and its abutments during strong earthquake. Many advances have been made in developing design codes and guidelines for dynamic analyses of non-skewed bridges. However, there remain significant uncertainties with regard to the structural response of skewed bridges caused by unusual seismic response characteristics. The purpose of this study is performing non-linear time history analysis of the bridges using abutment-soil interaction model considering pounding between the skewed deck and its abutments, and analyzing global seismic behavior characteristics of the skewed bridges to assess the possibility of unseating. Refined bridge model with abutment back fill, shear key and elastomeric bearing was developed using non-linear spring element. In order to evaluate the amplification of longitudinal and transverse displacement response, non-linear time history analysis was performed for single span bridges. Far-fault and near-fault ground motions were used as input ground motions. According to each parameter, seismic behavior of skewed bridges was evaluated.