基于性能的桥梁结构概率地震需求分析

该研究以概率地震需求分析为基础,建立了某特大桥梁结构无阻尼器和有阻尼器动力非线性模型,用增量动力分析,得到支座最大相对位移的地震响应,并定义了两个性能水准。给出了结构的易损性曲线,并对两个结构的易损性曲线进行了比较,结合地震危险性曲线,得到结构在50年内的地震需求危险性曲线。研究结果表明:不加阻尼器时50年内发生碰撞的超越概率接近极限超越概率,加阻尼器后能很好的满足性能水准要求;在小震中阻尼器对结构的抗震性能提高不是很明显,而在大震中能够对结构的抗震性能提高很多。

PERFORMANCE-BASED PROBABILISTIC SEISMIC DEMAND ANALYSIS OF BRIDGE STRUCTURES

Based on probabilistic seismic demand analysis,this paper established the dynamic non-linear models of the bridge structure with and without dashpots.The maximum relative displacement of the activity bearings was obtained by incremental dynamic analysis and two performance levels were defined.The fragility curves of the two structures were presented and compared.Combining the fragility curve with seismic hazard curve,the 50 years demand hazard curves of the structure were obtained.The results show that,during fifty years,the exceeding probability of collision of the bridge without dashpots was close to the limit probability;nevertheless,it was decreased significantly with dashpots installed,such that the requirement of performance levels can be satisfied.During weak earthquakes,the effect of dashpots to improve structural seismic performance was not as evident as during strong earthquakes.