考虑轴压比和剪跨比的RC墩柱拟静力试验及地震易损性分析

Seismic vulnerability analysis and pseudo-static test of reinforced concrete piers with different axial compression ratios and shear span ratios

为评估RC墩柱的抗震能力,基于矩形柱拟静力试验和OpenSees数值模拟,以截面弯矩-曲率为损伤指标,对RC墩柱进行地震易损性分析。基于增量动力分析方法,对10条地震波分别进行0.05g、0.1g、0.2g、0.3g、0.4g、0.5g调幅,采用LHS方法进行随机抽样生成60个地震动-结构样本对,考虑轴压比0.1、0.2、0.3,剪跨比(柱高)4.3、3.0、2.5,共300个工况进行IDA分析。结果表明:不同破坏状态墩柱的超越概率和地震易损性随着地面峰值加速度(PGA)的增大而增大;在PGA相同的的条件下,随着轴压比的增大,墩柱4种破坏状态对应的超越概率随之增加;PGA由0变化到超过0.3 g的过程中,其发生的超越概率增加很快。剪跨比影响方面,PGA相同时,发生4种破坏的超越概率随着剪跨比的增大而减小;PGA=0.5g时,剪跨比4.3和3的墩柱的超越概率均超过了80%,剪跨比为2.5墩柱超越概率小于50%。当墩柱需要满足抗震性能以及结构延性要求时,RC墩柱的轴压比设计值应低于0.3。在不同剪跨比下,RC墩柱在轻微破坏-中等破坏-严重破坏的过程中超越概率的降低幅度不大。

In order to evaluate the seismic capacity of RC pier columns,based on the pseudo-static test of rectangular columns and OpenSees numerical simulation,the seismic vulnerability analysis of RC pier columns is carried out with the section bending moment-curvature as the damage index.Based on the incremental dynamic analysis method,0.05g,0.1g,0.2g,0.3g,0.4g,and 0.5g amplitude modulation are performed on 10 seismic waves respectively,and 60 earthquake-structure sample pairs are generated by random sampling using the LHS method.Pressure ratio 0.1,0.2,0.3,shear-span ratio(column height)4.3,3.0,2.5,a total of 300 working conditions for IDA analysis.The results show that:The overrun probability and seismic vulnerability of piers with different damage states increase with the increase of peak ground acceleration(PGA);under the condition of the same PGA,the overrun probability corresponding to the four damage states of piers increases with the increase of axial pressure ratio;when the PGA changes from 0 to over 0.3 g,the exceedance probability increases rapidly.In terms of the influence of the shear-span ratio,when the PGA is the same,the exceedance probability of the four kinds of failures decreases with the increase of the shear-span ratio;when PGA=0.5g,the exceeding probability of piers with shear-span ratio 4.3 and 3 exceeds 80%,and that of piers with shear-span ratio 2.5 is less than 50%.When the piers need to meet the seismic performance and structural ductility requirements,the design value of the axial compression ratio of RC piers should be less than 0.3.The decrease in the exceedance probability of RC piers in the process of slight damage-moderate damage-severe damage is not significant for different shear span ratios.