“顶吸基隔”结构非平稳随机地震反应分析新方法

为了有效抑制基础隔震结构的隔震层及主结构的过大位移,设计了"顶吸基隔"减震结构并提出了相应的非平稳随机反应分析新方法.通过在基础隔震结构的顶部布置调谐质量阻尼器来构建减震结构,分别采用Bouc-Wen模型及其刚度退化模型模拟隔震层及各楼层的滞回特性.通过在精细积分法中引入复化Cotes积分,并结合虚拟激励法,提出了求解减震结构非平稳随机反应的CCIM法.依据首次超越破坏准则,建立了以结构层间位移角为评价指标的动力可靠度极限状态方程.通过分别采用CCIM、蒙特卡罗法和时域显式蒙特卡罗法对减震结构进行随机反应分析,验证了CCIM具有高效率和高精度的特点.以一座30层钢框架结构为算例,分别计算了减震结构、基础隔震结构和未控制结构在8度和9度罕遇地震作用下的随机反应.结果表明:本文提出的"顶吸基隔"减震结构的整体可靠度比基础隔震结构和未隔震结构的都要高,该减震结构具有极大的工程推广价值.

A New Method for Analyzing the Non-stationary Random Seismic Responses of Structure with Top-absorption and Base-isolation

To effectively suppress the larger displacement of both the isolation layer and the main structure of base-isolation structures, the top-absorption and base-isolation type seismic reduction structure (SRS) was designed, and a new non-stationary random seismic response analysis method applied to this structure was also presented. This seismic reduction structure was constructed by installing a tuned mass damper on the top of a base-isolation structure, and the hysteretic properties of both the isolation layer and each storey were simulated in Bouc-Wen and Bouc-Wen stiffness degradation model. The CCIM, which was applied to solve the non-stationary random response of SRS, was presented by introducing the composite Cotes integral into precise integral method and combining the pseudo excitation method. The dynamic reliability limits state equation, which took structural inter-storey displacement angle as the evaluation index, was established on the basis of the first excursion failure criterion. Both the high efficiency and the high precision of the CCIM were validated by computing the random seismic response of SRS and comparing CCIM's results with those of Monte Carlo method and time domain explicit Monte Carlo method, respectively. Taking the 30-storey steel frame structure as a numerical example, the random seismic response of SRS, base-isolation and non-isolation structures subjected to 8 and 9 degrees rare earthquake were computed, respectively. The analysis results indicate that the whole reliability of SRS presented is higher than those of base-isolation and non-isolation structures, and this SRS has great value in practical engineering.