Seismic Vulnerability Analysis of Bridges in Mountainous States.

摘要

Depending on the location, highway bridges can often support considerable amounts of traffic. Due to the limitations on current earthquake forecasting techniques, a normal amount of traffic will also typically remain on a bridge when an earthquake occurs. In addition to traffic, scour effects are also a potential hazard to bridge piers that may simultaneously impact the structural integrity of the bridge together with seismic loads. Although a few studies investigating the combined effect of extreme and service loads have been conducted on long-span bridges or in high-seismic zones, the studies on typical short- and medium-span bridges in low and moderate seismic zones are rare. A general dynamic simulation methodology is introduced to study the combined realistic service and extreme loads on short- and medium-span bridges. Following the introduction of the methodology, a numerical study investigating the seismic performance of a typical highway bridge in mountainous states is carried out. The bridge is subjected to different combinations of traffic, seismic, and scour and the effects on the structural performance of the bridge are investigated. The bridge, including both superstructure and substructure, is modeled in detail using SAP2000 to accommodate the goals of this study. The traffic load is considered through dynamic interaction analysis of vehicles in the simulated stochastic traffic flow. Through studying the bridge performance under various combined extreme and service loads, findings are made about controlling cases for different bridge responses and the validity of the traditional superposition approach with consideration to load combinations is also discussed.