Experimental study on the seismic performance of a curved bridge via large-scale hybrid tests

Abstract

The Huilan interchange built in Mianzhu City, China, in 2004 experienced serious damages during the Wenchuan earthquake in 2008. Due to the irregularity and eccentricity, the curved ramp bridge suffered significant spatial action from the earthquake shaking, where several short piers failed in a bending-shearing-torsional mixed damage pattern. To ascertain the reason for the failure of short piers, the seismic performance of the curved bridge was reproduced and evaluated by large-scale hybrid tests. In the hybrid tests, the curved bridge C was selected as the prototype structure to reproduce the failure scenario, for which the 3/4 scale model of pier No. 2 was physically tested by a large spatial loading system to reproduce the spatial failure mode in all six degrees of freedom. The rest of the structure was modeled by OpenSees to simulate the earthquake response. Several rounds of hybrid tests were conducted, and it was found that pier No. 2 first yielded in the flexural mode, then changed to the mixed flexural-shear mode, and finally failed in the shear mode with a torsion effect. These results are generally consistent with the post-earthquake observations.