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考虑桥梁结构的服役期对地震荷载的影响,应用等超越概率的方法将地震作用进行折减,将公路桥梁抗震规范中的两级设防标准扩展为三级设防标准。考虑地震动的随机性,应用概率理论将目标反应谱随机化,结合相干函数和相位差谱理论,采用MATLAB程序,生成在役桥梁结构空间相关多点非平稳随机地震动。模拟结果表明:应用等超越概率的方法可以将地震动峰值加速度进行合理折减;应用概率理论进行反应谱随机抽样,得到的随机地震反应谱能够较好地反映地震动的随机性,其中30条随机反应谱的变异系数最大差值为0.064,精度符合要求;计算反应谱与随机目标反应谱拟合情况良好,1、2号目标点的拟合优度值分别为0.82和0.81,精度符合要求;合成的人工地震动能够反映在役桥梁结构的已服役期和地震动的随机性,接近实际的地震记录。
Considering the influence of service life of bridge structure on earthquake load, the method of transcendental probability is applied to reduce the seismic effect and the two-stage fortification standard in the seismic code of highway bridges is extended to the third-level fortification standard. Considering the randomness of ground motion, probability theory is used to randomize the target response spectrum. Combined with the theory of coherence function and phase difference spectrum, a MATLAB program is used to generate multi-point non-stationary random ground motions of the existing bridge structures. The simulation results show that the application of equal probability method can reasonably reduce the peak acceleration of ground motions. Using the probability theory to conduct random sampling of response spectrum, the random seismic response spectrum obtained can well reflect the randomness of ground motions. Among them, 30 The maximum difference of the coefficient of variation of the random response spectrum was 0.064, the accuracy meets the requirements. The calculated response spectrum and the random target response spectrum fit well. The goodness of fit of the target points of No.1 and No.2 were 0.82 and 0.81 respectively, Synthetic artificial ground motion can reflect the service life of existing bridge structures and the randomness of ground motion, which is close to the actual seismic record.