Shake table test on transverse steel damper seismic system for long span cable stayed bridges
Abstract In current transverse seismic design of long span cable stayed bridges, the conventional transverse fixed system (TFS) is usually adopted. This strategy inevitably increases seismic demands of substructures and towers, leading to high seismic induced damage risks to the bridges. To address this issue, the authors recently developed a novel Transverse Steel Damper (TSD) and correspondingly proposed an innovative TSD seismic system (TSDSS) in which the TSDs were placed at deck tower and/or deck bent connections. To further verify the reliability and seismic isolation efficiency of TSDSS for long span cable stayed bridges under near and far fault ground motions, a series of experiments on a 1/35 scale model of a kilometer span cable stayed bridge were conducted on a four shake table testing system. Experimental results indicate that (1) compared with the conventional TFS, the TSDSS can reduce transverse displacement and curvature demands along bent/tower columns, meanwhile limiting displacements at deck bent/tower connections to an acceptable level in engineering practice. (2) The sensitivity of TSDSS to ground motions is obviously lower than that of the conventional TFS. The isolation efficiency of TSDSS is robust regardless under near or far fault ground motions; (3) Increasing the yield strength of TSDs can decrease the relative displacements at deck bent/tower connections. In general, the TSDSS is experimentally validated to be a capable and reliable strategy for the seismic design of long span cable stayed bridges. Additionally, the shake table test is simulated using a finite element model, which provides good agreements with the test results.