Seismic Performance of Steel-Concrete Composite Rigid-Frame Bridge: Shake Table Test and Numerical Simulation

The composite rigid-frame bridge presented in this study is a new type of structural solution that combines the steel-concrete composite box girder and the concrete-filled double-skin steel tube (CFDST) piers with rigid connecting joints. Compared with the conventional prestressed concrete rigid-frame bridge, it shows superior static and dynamic performances. This study performs shake table tests of a 1:10-scaled three-span steel-concrete composite rigid-frame bridge (SCCRFB) to explore its seismic characteristics and damage modes. The details of the bridge model design, construction, measurements, and testing process are presented. The seismic responses of the bridge under one typical near-fault and one far-field ground motions were experimentally investigated. Testing results revealed that the damage to the bridge is mainly located at the upper and lower ends of the CFDST piers, with yielding of the outer steel box and separation between the steel skins and infilled concrete. The testing results also indicated that the near-fault ground motions containing strong velocity pulse could significantly amplify the structural responses compared with the far-field ground motions. Furthermore, a detailed finite element (FE) model of the SCCRFB with CFDST piers is developed and validated by the experimental results, and numerical studies are then carried out to compare the seismic performances of this bridge type and the one supported by the conventional reinforced concrete (RC) piers. The numerical results show that the SCCRFB with CFDST piers exhibits superior seismic performances compared with the traditional bridge, especially when subjected to the near-fault ground motions. This study can provide useful references for the engineering solution and seismic design of long-span, high-pier composite rigid-frame bridges.