地震持时和安全阈值对结构抗震可靠度的影响研究*

为深入掌握结构在地震作用下的可靠性,研究地震激励时间及安全界限对结构抗震可靠性的影响。基于Matlab,首先对结构在高斯过滤白噪声地震动模型(Kanai-Tajimi谱)激励下的随机响应进行了分析,然后分别采用泊松过程法、马尔科夫过程法、瑞利极值分布法对结构随机响应过程超越安全界限的概率进行了计算,三者结果基本接近,较可靠地反映出结构动力可靠度变化规律。结果表明,结构动力可靠度随激励时间的增长而下降,当安全界限大于某确定值时,动力可靠度与激励时间的关系接近于线性,当安全界限小于该值时,动力可靠度与激励时间呈二次非线性关系;结构动力可靠度随安全界限增大而增大,激励时间越长,动力可靠度与安全界限关系曲线越陡,激励时间越短,动力可靠度与安全界限关系曲线越平缓。

Effect of Seismic Duration and Safety Bound on Structural Seismic Reliability

In order to further grasp the structural reliability under earthquake, the effect of seismic duration and safety bound on structural seismic reliability are studied in this paper. Using MATLAB the random responses under the earthquake ground motion model of Gauss filtered white noise (Kanai-Tajimi spectrum) is analyzed. Then the exceeding probability of random response process is calculated using Poisson process method and Markov process method and Rayleigh extreme value distribution method. The calculation results of the three methods are similar, which show the change law of the structural dynamic reliability. The calculation results show that the structural dynamic reliability decreases when the excitation time increases. When the safety bound is greater than a certain value, the relationship between the dynamic reliability and the excitation time is close to linear. When the safety bound is less than that value, the relationship between the dynamic reliability and the excitation time is quadratically nonlinear. The structural dynamic reliability increases with the increasing of safety bound. The longer the excitations time, the steeper the curve between dynamic reliability and safety bound will be. The shorter the excitation time, the more smooth the curve between dynamic reliability and safety bound will be.