大跨度拱形空间桁架干煤棚的地震易损性分析

Seismic fragility analysis of large-span arch truss of dry coal shed

拱形空间桁架具有自重轻、结构效率高、造型美观多样、施工安装方便等优势,现广泛应用于公共展厅、体育馆、火车站、工业库房等大跨度空间建筑。然而,地震作用下拱形空间桁架存在结构整体平面外失稳、杆件屈服、支座破坏等潜在风险,需要进行抗震验算。基于此,本文对一电厂干煤棚的大跨度拱形空间桁架进行了地震易损性分析,获得了地震易损性曲线,对其抗震性能进行了评价。主要内容包括:首先,对拱形空间桁架干煤棚进行了有限元建模,对其动力特性进行了分析;之后,以地震动峰值加速度作为强度指标,依据非平稳地震动的演变功率谱模型,采用谱表现方法模拟获得了地震动时程样本,计算了结构地震响应;进一步,采用基于结构整体损伤指标的能力需求比模型曲线拟合法,获得了拱形空间桁架的地震易损性曲线;最后,依据地震易损性分析结果,对结构地震安全性进行了评价,给出了改进意见。结果表明,此拱形空间桁架横向抗震性能明显强于纵向,纵向地震作用易引起结构失效,应采取必要措施提高其纵向抗震性能。

Because of its light weight,high structural efficiency,diverse shape,convenient construction,arch truss is widely used in public exhibition hall,stadium,railway station,industrial warehouse and other large-span space buildings.However,under earthquake action,arch truss has potential risks such as out-of-plane instability,member yield and bearing failure.Hence,the seismic verification of arch truss is required.This paper analyzes the seismic fragility and evaluates the seismic performance of large-span arch truss.Firstly,the finite element model of arch truss is built and its dynamic characteristics are presented;Then,by using the evolutionary spectrum model of non-stationary seismic ground motions,the spectral representation method is applied to simulate earthquake time history samples;Furthermore,the seismic fragility curves of the arch truss are calculated by using the capacity demand ratio curve fitting method;Finally,according to the results of seismic vulnerability analysis,the seismic safety of arch truss is evaluated and the improvement suggestions are given.The results show that the lateral seismic ability of the arch truss is obviously stronger than that of the longitudinal direction.The longitudinal seismic action easily causes the structural failure.It is necessary to improve the longitudinal seismic performance of the arch truss.