Seismic evaluation of skew bridge with friction type rubber bearings - Experiments and case studies

The seismic response of the skew bridges with rubber bearing is studied. In Taiwan, simply-supported PCI bridges are widely used with rubber bearing pads as a supporting system. It is common seen that, during the construction practice, the rubber bearing pads have been laid on the cement mortar-made bearing pads without any details of bolting design. This kind of arrangement potentially allows rubber bearing to slide, so as the superstructure when the earthquake occurs. In addition, bridges are usually being skewed to provide transportation service, requiring a further investigation of seat width to avoid falling of the superstructure. In this study, firstly, a series of friction coefficient was conducted. Furthermore, a scale-down skew bridge model has been constructed to perform the shaking table test. According to the experimental results, the inertial forces from superstructure can be reduced because of the sliding-induced isolation effect. The analytical program, SAP2000N was used to simulate the experimental results, and it has been shown the numerical model can predict the acceptable displacement demand. Based on the parametric study, finally, the study will discuss the bridge behaviors with different skew angles and input directions of time histories.