Experimental Study of the Aseismic Effect of a Locking Ball for a Continuous Bridge

Abstract

Current sliding-bearing designs do not make full use of the stiffness and potential ability of sliding piers in the aseismic design of continuous bridges. Aiming at the problem that the demand on the only fixed-pier force and beam-end longitudinal displacement is too large under longitudinal direction earthquakes, an aseismic design idea of a continuous bridge is proposed based on coloading of all piers by installing locking balls between the sliding piers and the continuous girder. This device can also handle displacement caused by rise and drop in temperature. When a strong earthquake occurs, the locking ball is activated, and the locking connections between the girder and the sliding piers were built to let the sliding piers carry the longitudinal seismic load of the superstructure in conjunction with the fixed pier. A vibration-table experiment on a three-span continuous bridge with a scale of 1:25 was conducted, and results were compared with finite-element model (FEM) simulations. The aseismic effect and the mechanism of the locking ball on the continuous bridge were analyzed. The results showed that the sliding piers can bear the longitudinal seismic load of the upper structure in conjunction with the fixed pier under strong earthquake conditions and can improve the overall aseismic performance of the continuous bridge significantly. Meanwhile, the seismic demands on the sliding piers increased. The number of spans and the length of the continuous girder had an influence on the locking-ball aseismic effect. However, the variation of temperature had little influence on the aseismic effect of the locking ball.