大跨度空间网格结构多维多点随机地震反应分析

Random seismic response analysis of long-span spatial lattice structure under three-dimensional and multi-support earthquake excitations

本文建立了三维正交地震动多点激励下大跨度空间网格结构的随机地震反应分析方法,依据现行抗震设计规范的有关规定,确定了平稳随机地震动功率谱密度的模型参数。数值仿真分析了一柱距80m的正方形平板网架分别在一维地震动或三维地震动的一致激励、行波激励和考虑部分相干效应的随机激励下的地震反应。结果表明:考虑地震动的空间效应会很大程度地改变结构杆件的内力,其中控制杆件的内力增幅达到30%;地震动的行波效应对结构杆件内力的影响比随机地震动的部分相干效应的影响更大;三维地震作用比一维地震作用下结构杆件的内力大。由此得出结论,对于大跨度空间网格结构,必须进行多维多点地震激励下的随机地震反应分析。

In this paper, the method of random seismic response analysis for long-span spatial lattice structures under the multi-support excitations of three-dimensional orthogonal earthquake motion is established. The model parameters of the power spectral density of the stationary random earthquake motion are determined according to the related specification of current code for seismic design. The seismic responses of a square plate grid with a uniform column spacing of 80m are numerically simulated under the uniform excitation, the traveling-wave excitation and the random excitation considering the partial coherence effect of the one-dimensional and three-dimensional earthquake motions. The results show that the internal forces of structural bars may be greatly changed by Considering the spatial effect of earthquake motion, in which the amplitudes of the internal forces of the controlling bars may be increased by 30%. The influence of the traveling-wave effect of the earthquake motion on the internal forces of structural bars is stronger than that of the partial coherence effect of the random earthquake motion. The internal forces of structural bars under the three-dimensional earthquake excitation are larger than that under the one-dimensional excitation. A conclusion is drawn that the random seismic analysis considering the multi-support excitations of three-dimensional earthquake motion must be performed for the long-span spatial lattice structures.