树状柱支撑曲面单层网壳结构受力性能的直接分析法研究

Research on direct analysis method for structural behavior of dendritic column-supported single-layer curved surface reticulated shells

钢结构直接分析法考虑结构稳定性相关因素,能够准确地表征结构真实响应。为此,以树状柱支撑曲面单层网壳结构为研究对象,采用NIDA和SAP2000有限元软件,考虑荷载不对称分布和初始缺陷等因素,通过直接分析法对结构静力性能、稳定性和抗震性能进行研究,并与计算长度法结果对比。结果表明:静力荷载作用下,不同软件采用计算长度法时结果基本相同,NIDA直接分析法(弹性)得到的杆件应力比均值较计算长度法小;材料非线性模拟方法的不同以及忽略杆件初始缺陷,使得采用SAP2000比NIDA非线性屈曲得到的稳定承载力高;多遇地震作用下,计算长度法和直接分析法得到的受压杆件应力比差别较大,压弯构件应力比无显著差异;罕遇地震作用下,采用直接分析法考虑杆件初始缺陷时,结构加载控制点竖向峰值位移比不考虑时的增大0.25%,考虑结构初始缺陷时比无缺陷情况下加载控制点竖向峰值位移增大35.7%。

Direct analysis method(DAM)considers the relevant factors affecting the structural stability,and the true structural response can be reflected accurately.Based on the dendritic column-supported single-layer curved surface reticulated shell,the static performance,stability,and seismic performance were investigated using DAM by finite element analysis software NIDA and SAP2000,and the results were compared with the effective length method(ELM),considering load asymmetry and initial imperfection.The result indicates that the results are basically the same when the DAM is adopted by different software,and the average stress ratio of members obtained by DAM(elastic)of NIDA is smaller than the ELM under static load.The different nonlinear simulation methods of materials and the neglect of initial member imperfection make the nonlinear buckling capacity of SAP2000 higher than that of NIDA.ELM and DAM have a greater impact on the stress ratio of the compression member when experiencing frequent earthquakes and basically have no effect on the stress ratio of members under eccentric compression.Under rare earthquakes,the vertical peak displacement of the loading control point is 0.25%larger than that without considering the initial member imperfections by DAM,and 35.7%larger when the initial structure imperfections are considered than that without.