叠合柱高墩概率地震易损性分析

Probabilistic seismic fragility analysis of high pier of steel tube-reinforced concrete column

为了评估叠合柱高墩的抗震性能,根据结构可靠度理论,推导了概率地震易损性函数解析式。以一座叠合柱高墩连续刚构为研究对象,对叠合柱高墩的合理性能指标进行分析和量化,建立了以轴力为变量的截面概率抗震能力模型。考虑材料强度和地震动的不确定性,采用IDA方法对结构-地震动样本进行地震需求分析,建立了以PGA为变量的控制截面概率地震需求模型并进行概率地震易损性分析。结果表明曲率指标对数均值与对数轴力之间符合三次多项式回归关系,曲率抗震能力随轴力的增大而减小。在纵向地震作用下,曲率需求与PGA之间仍然满足对数线性关系,墩底区域最容易发生损伤,矮墩比高墩更容易发生损伤,在设计地震作用下,叠合柱高墩发生倒塌的概率极小。

In order to assess the seismic performance of high pier of steel tube-reinforced concrete column,according to the theory of structure reliability,resolution function of probabilistic seismic fragility was deduced. A continuous rigid frame bridge with high pier of steel tube-reinforced concrete column was taken as the research object,reasonable performance index of high pier of steel tube-reinforced concrete column was analysed and quantified,the probabilistic seismic capacity model for the section of steel tube-reinforced concrete column with axial force as the variable was built. Considering the uncertainty of steel tube-reinforced concrete column material strength and the ground motion,seismic demand of structure-seismic samples was analysed using IDA method,and the probabilistic seismic demand model for control sections with PGA as the variable was built. And probabilistic seismic fragility of of high pier control sections is obtained. The results show that the logarithmic mean value of curvature index and logarithmic axial force consistented with the three polynomial regression relationships,and seismic capacity of curvature decreased with the axial force increased. Curvature demand and PGA still meet the logarithm linear relationships under the longitudinal seismic. The bottom region of pier is most easily damaged,and the shorter pier of structure system is more easily damaged than higer pier. The high pier of steel tube-reinforced concrete column is hardly collapsed under design seimic.