考虑风致疲劳效应的高层框-剪隔震结构地震易损性分析

Seismic Vulnerability Analysis of High-rise Frame-shear Isolation Structure Considering Wind-induced Fatigue Effect

高烈度、高风压地区的高层隔震结构在较大风荷载作用下会增大隔震层位移,长期风振作用下隔震支座也容易产生疲劳累积损伤,从而影响其抗震性能。为研究长期风荷载作用下风致疲劳对高层隔震结构抗震性能的影响,以高层框-剪隔震结构为研究对象,利用OpenSees建立了考虑隔震支座发生疲劳损伤的风致疲劳模型,分析了地震作用下高层框-剪隔震结构的动力响应规律,并基于多维性能指标进行了高层框-剪隔震结构的地震易损性分析。分析结果表明,随着隔震支座疲劳程度的加深,虽然上部结构的加速度响应和基底剪力均有一定程度降低,但隔震层位移显著增大,支座更容易出现超限变形而导致隔震层失效;隔震支座发生风致疲劳损伤时,隔震层失效概率增大,导致结构整体失效概率增大;同时考虑层间位移角和隔震层位移双指标的结构失效概率均大于两者单独考虑的单指标失效概率。建议对高风压地区的高层隔震结构进行全寿命抗震性能评估时应考虑风致疲劳效应的影响,进行地震易损性分析时应综合考虑上部结构与隔震层的影响,避免高估此类结构的抗震性能。

High-rise isolated structures in high intensity and high wind pressure areas will increase the displacement of the isolation layer under large wind loads, and the isolation bearings are prone to fatigue accumulation damage under long-term wind vibration, thus affecting their seismic performance. In order to study the effect of wind-induced fatigue on the seismic performance of high-rise isolated structures under long term wind load, taking high-rise frame-shear isolator structures as the research object, a wind-induced fatigue model considering the fatigue damage of bearings is established by OpenSees. The dynamic response rule of high-rise frame-shear isolation structure under earthquake is analyzed, and the seismic vulnerability of high-rise frame-shear isolation structure is analyzed based on multi-dimensional performance indexes. The analysis results show that with the increase of the fatigue degree of the isolation bearing, although the acceleration response and the base shear of the superstructure decrease to a certain extent, the displacement of the isolation layer increases significantly, and the bearing is more prone to overrun deformation, resulting in the failure of the isolation layer;when the isolation bearing suffers from wind-induced fatigue damage, the failure probability of the isolation layer increases, resulting in an increase in the overall failure probability of the structure;the structural failure probability considering double indexes of interlayer drift ratio and bearing displacement is greater than the single index failure probability considering both separately. It is suggested that the influence of wind-induced fatigue should be considered in the whole life seismic performance evaluation of high-rise isolated structures in high wind pressure areas, and the influence of superstructure and isolation layer should be comprehensively considered in the seismic vulnerability analysis to avoid overestimating the seismic performance of such structures.