钢筋混凝土框架结构竖向不规则参数的概率评估

采用蒙特卡罗模拟方法分析钢筋混凝土(RC)框架结构竖向不规则参数的抗震控制效果。以底层和中间层竖向楼层承载力和刚度不规则的5层和10层RC框架结构为分析对象，考虑地震动输入的随机性，通过非线性动力时程分析确定结构的最大层间位移角，并分析其随竖向不规则系数变化的规律和超越极限状态水准的失效概率。分析结果表明：楼层竖向承载力和刚度不规则对结构最大层间位移角的影响较大，最大层间位移角随竖向不规则系数的减小而增大，底层不规则较中间层不规则的影响大，承载力不规则较刚度不规则的影响大；竖向不规则对结构地震反应超越极限状态水准的失效概率有显著的影响，失效概率随竖向不规则系数的减小而增大，竖向不规则系数越小失效概率越大；承载力不规则系数为0.7和刚度不规则系数为0.8可作为竖向不规则参数的抗震控制点。

Probability evaluation of vertical irregularity parametersfor reinforced concrete frame structures

Based on the Monte Carlo simulation method, seismic control effect of vertical irregularity parameters for reinforced concrete (RC) frame structures were studied. Employing a 5-story and a 10-story frame structures with vertical irregularities of strength or stiffness on the first story and on the median story, and considering earthquake action as the random variable, nonlinear dynamic time history analysis was conducted to investigate the maximum inter-story drift angle. The variation rule of the maximum inter-story drift angle with different vertical irregularities was explored, and the probability of failure exceeding the limit state was evaluated. The results show that the vertical strength irregularity and stiffness irregularity have significant effects on the response of the maximum inter-story drift angle. With the decreases of strength irregularity and stiffness irregularity factors, the maximum inter-story drifts increase. The vertical irregularities on the first story have a larger effect upon the structure’s inter-story drift than the vertical irregularities have on the median story, and strength irregularities have relatively greater effect upon the structure’s inter-story drift than the stiffness irregularities have. The vertical irregularities also have significant effect on the probability of failure for structures exceeding the limit state criteria. The exceeding probability increases as the vertical irregularity factor decreases. The smaller the irregular factor and the lower the limit state criteria are, the more significant this phenomenon becomes. The strength irregularity factor of 0.7 and the stiffness irregularity factor of 0.8 can be set as the seismic control limit.