Torsional Response Of Simply-Supported Girder Bridge Subjected To Ground Motion

In recent years, earthquake happened frequently at home and abroad, especially the last several large earthquakes, which have brought a great loss to people's life and property. Timely post-earthquake rescue work has great significance in reducing the earthquake damage. Bridge, as a key in transportation lifeline project, is very important at this time. Many post-earthquake investigations showed that bridges produced a torque response, sometimes these torsional response may cause great destruction to the bridge. Therefore, studies on the torsional response of a bridge after earthquakes have a great important practical significance.Using a simple supported girder bridge as a model, this paper analyzed of the torsional response and influence factors of the simple supported girder bridge under earthquake. The main contents of this article are as follows,1. The basic of the bridge dynamics was briefly introduced. Then the development of the earthquake simulation analysis theory of the bridge was stated. The basic concepts and development of the static method, the dynamic response spectrum method, schedule and random vibration analysis method were also briefly introduced. Also, the reasons that may cause the seismic torsional response of a bridge in reality were analyzed, including structure eccentric, structure accidental eccentric in earthquake, the influence of the site conditions, the earthquake traveling wave effect and the rotation component of the seismic oscillation. And the research of bridge seismic excitation torsional response analysis focused on the traveling wave effect of earthquake transmission and the influence of the support to the bridges.2. A 3-span simply-supported girder bridge model was built. Bridge pad, as the key in the bridge movement under earthquake, was meticulously simulated. Through the establishment of nonlinear restoring force model, the kinetics characteristics of common slab rubber bearings, ptfe skateboarding rubber bearings, basin type bearings and lead lead-rubber bearings were simulated respectively.3. Time history method was used to analyze simple supported girder bridge. According to the different inputs of seismic oscillation and the adjustment of the support form, the impact to the seismic torsional response of a bridge was analyzed. And also, the seismic torsional responses of a simple support girderbridge under different motivational pattern, different bridge spans position and different support form were compared respectively.