Unseating of single-span bridges with skew angles out of the limit range for free rotation

Wu, Suiwen; Huang, Junfei; Li, Weifeng; Jiao, Chiyu; Li, Jianzhong

doi:10.1016/j.istruc.2021.03.088

Cited by 2 publications

(1 citation statement)

References 19 publications

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“…S.W. Wu et al [20][21][22] studied the limit range of free rotation of the main beam of a bridge with or without expansion joints by a shaking table test, and verify the rationality of the finite element modeling. Additionally, the artificial neural network method is used to determine the relative importance of each uncertain parameter on the vulnerability curve of skew bridge piers [23].…”

Section: Introductionmentioning

confidence: 99%

Determination of reasonable parameters for skew bridge under different skew angles

Yin¹,

Wang²,

Guo³

2023

J. vibroeng.

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A finite element model is created using OpenSees software to perform a time history analysis in order to analyze the seismic response law of a skew bridge and the damage volume of its key components, using a typical 3×20 m skew continuous girder bridge as an example. The seismic response of the skew continuous girder bridge under various factors such as the size of the abutment expansion joint, shear key gap, and shear key strength is studied then the damage rate is assessed for the bearing, shear key, and pier. The research results show that under the action of earthquake ground motion with 0.3 g PGA, the seismic force transmitted to the pier is small, and the pier is elastic owing to the sliding of the bearing, but the damage degree of the shear key is larger than that of the bearing and pier. The impact increases the rotation effect of the main beam in the direction of off acute angle, resulting in a greater damage to the shear key at the acute angle than that at the obtuse angle. The damage of bearing and shear key increases and then decreases with the increasing of expansion joint, and the larger the skew angle is, the smaller the expansion joint will be corresponding to the maximum displacement of bearing and shear key. With the increase of the shear key gap, the deformation limitation effect of the shear key on the main beam decreases significantly, resulting in a linear increase in the bearing slip, which increases the risk of the main beam subsidence. With the increase of the shear key strength, the bearing and shear key damage decreases greatly at first, and then increases slightly. However, the pier damage increases obviously. In an area with a high risk of earthquake, it is recommended that the shear key can be a “fuse element”. For any oblique angle, the shear key gap can be reduced to 2 cm, and the shear key strength can be increased to 125 % or 150 %. When the skew angle is between 30 and 60, the expansion joint size can be increased to 12 cm or 16 cm.

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Section: Introductionmentioning

confidence: 99%

Determination of reasonable parameters for skew bridge under different skew angles

Yin¹,

Wang²,

Guo³

2023

J. vibroeng.

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Study on the additional support length requirements of single-span bridges due to skew using a simplified method

Jia

Jiao

et al. 2021

ABEN

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Skew bridges with seat-type abutments are frequently unseated in earthquakes due to large transverse displacements at their acute corners. It is believed these large displacements are due to in-plane rotation of the superstructure. Lack of detailed guidelines for modeling of skew bridges, many current design codes give empirical expressions rather than theoretical solutions for the additional support length required in skew bridges to prevent unseating. In this paper, a parametric study has been carried out to study the influence of skew angle, aspect ratio and fundamental periods of bridges on the additional support length requirements of single-span bridges due to skew using a shake table experiment validated Simplified Method, which is capable of simulating gap closure based on response spectrum analysis. This method is developed based on the premise that the obtuse corner of the superstructure engages the adjacent back wall during lateral loading and rotates about this corner until the loading reverses direction. A design response spectrum specified in AASHTO LRFD Specifications was employed to represent the design-level earthquakes. The results show the additional length required to prevent unseating due to skew increases with the skew angle in an approximately linear manner when the angle is less than a critical value and decreases for angles above this value. This critical skew angle increases with the aspect ratio approximately in a linear manner and shows negligible dependence on the fundamental periods of the bridges, and combination of span length and width. In addition, the critical skew angle varies between 58° and 66°, when the aspect ratio is varied from 3.0 to 5.0. The results also show that the empirical formulas for minimum support length requirements of skew bridges in current codes and specifications can not accurately reflect the influence of skew.

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Unseating of single-span bridges with skew angles out of the limit range for free rotation

Cited by 2 publications

References 19 publications

Determination of reasonable parameters for skew bridge under different skew angles

Determination of reasonable parameters for skew bridge under different skew angles

Study on the additional support length requirements of single-span bridges due to skew using a simplified method

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