Abstract
In the seismic design of long-span bridges, the classic bi-linear model was used to simulate the frictional restoring force of the rubber bearings. However, in actual earthquake, the rubber bearing suffered fluctuating axial pressure in earthquake, even separated from the beam when vertical component of the earthquake was too strong. Employing the bi-linear model for the bearing may incorrectly estimate the seismic response of the bearings, as well as the whole bridge. This paper developed a nonlinear frictional bearing model, which can consider the variation of the frictional restoring force in the bearings, even the separation with the beam in vertical directions. A typical continuous beam bridge was modeled in ABAQUS, and incremental dynamic analysis was conducted for the quantitative comparison of the seismic responses using different bearing models. The intensity measure was selected as the ratio of the peak ground acceleration (PGA) in the vertical direction to the PGA in the horizontal direction. The analysis results indicated that the different bearing model led to the significant different seismic response for the bearings and piers, even the vertical component was small. The bi-linear bearing model would underestimate the seismic demand of the bearing and piers.
Highlights
Rubber bearings were widely used in bridge engineering owing to its economy, durability and easy construction, i.e. basin-type rubber bearing and panel-type rubber bearing.In general, the rubber bearing has very large compressive stiffness and load-carrying capacity in vertical direction, and provides frictional restoring force in horizontal directions (Yang et al 2017; Jiang et al 2019; Ding et al 2019)
While side bearing subjected to 2.54 times of the gravity load under the same intensity ratio (IR)
5 Conclusion This paper conducted the quantitative comparison on the seismic performance of the continuous beam bridge with the nonlinear frictional bearing model, which employed the frictional model for the bearings, involving the fluctuation of the normal pressure and the corresponding variation of the frictional restoring force
Summary
The rubber bearing has very large compressive stiffness and load-carrying capacity in vertical direction, and provides frictional restoring force in horizontal directions (Yang et al 2017; Jiang et al 2019; Ding et al 2019). The classical bi-linear model was one of the most commonly used models in bridge engineering owing to its simplicity and efficiency (Wei et al 2018; Mazda et al 2016). When the ground motion had strong vertical component, the vertical load in the bearing varied significantly, resulting in the fluctuating restoring force. In this case, the simplified bi-linear model could not reproduce the actual behavior of the rubber bearing
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