地震动非平稳性对大跨度空间结构随机地震响应的影响

为了进一步完善大跨度空间结构的随机地震响应分析理论，提出了一种简便的、近似计算非平稳地震激励下结构峰值响应均值的算法，数值模拟了某体育馆大型网壳结构在平稳和非平稳地震激励下的随机地震响应．研究表明，考虑地震动的非平稳性后，各杆件的峰值响应会有不同程度的减小，约7．51％～23．3％；同时考虑行波效应和地震动非平稳性时，在地震激励的初期阶段，结构响应方差会发生变化，但不会给结构的峰值响应均值带来明显差异；不同地面视波速时，峰值响应均值的减小程度不同．由此得出，所提出的近似算法能够大幅度地减少大跨度空间结构随机地震响应分析的计算量；对于大跨度空间结构的随机地震响应分析，尤其当结构的阻尼比和自振频率很低时应考虑地震动的非平稳性；在分析地震动非平稳性的影响时，应同时考虑地震动的行波效应．

Influence of Nonstationarity of Earthquake Ground Motion on Random Seismic Response of Long-Span Spatial Structures

In order to perfect the theory of random seismic response analysis for long-span spatial structures, a simple approximate algorithm to calculate mean values of peak responses was presented for structures subject to nonstationary random ground excitations. The random seismic responses of a large reticulated shell structure of a gymnasium were numerically simulated for stationary and nonstationary cases. It was found that when considering nonstationarity of earthquake ground motion, the random seismic response of each member was reduced differently by about 7.51%- 23.3%. When wave passage effect and the nonstationarity were taken into account simultaneously, the variances of structural responses would vary in the early short period of the earthquake, but it could not make the mean values of peak responses different significantly. The reduction of the mean values of peak responses may be different due to various apparent wave velocities. Conclusions are given that the proposed approximate algorithm can reduce the computation quantity for the random seismic response analysis of long-span spatial structures. The nonstationarity of earthquake ground motion must be considered in the analysis, especially when damping ratios and natural vibration frequencies of structures are very low. And the wave passage effect of earthquake ground motion should be considered simultaneously when analyzing the influence of nonstationarity of earthquake ground motion.