剪切型支撑框架弹塑性失稳模式判定准则  

Determination of buckling mode for elastic-plastic braced frames

作　　者：童根树[1] 邢国然[1] 

机构地区：[1]浙江大学土木工程学系,浙江杭州310027

出　　处：《浙江大学学报（工学版）》2007年第7期1136-1142,共7页Journal of Zhejiang University：Engineering Science

基　　金：国家自然科学基金资助项目(50578140)

摘　　要：为确定水平力对支撑框架弹塑性极限承载力的影响,解决各国规范关于失稳模式判定存在的分歧,采用几何和材料非线性分析方法,考虑了残余应力、长细比、梁柱约束以及构件初始弯曲和结构初始侧移等因素,研究了剪切型支撑框架的稳定极限承载力与支撑刚度的关系,得到了水平力和竖向力共同作用下支撑框架临界支撑刚度公式和失稳模态判定准则,并对一系列层单元模型和2层2跨框架算例进行了弹塑性有限元验证.结果表明,建议公式简单实用,概念明确,且偏于安全.An approach was suggested to consider the effects of horizontal loads on elastic-plastic buckling of braced frames, and to eliminate the differences of buckling modes determination between different national codes. The instability of braced frames was studied by geometric and material nonlinear analysis taking into account residual stresses, slenderness, restraint of beam to column, initial sway imperfection and member initial bow. The change of buckling mode with the increase of bracing stiffness was analyzed and the relationship between the ultimate load capacity and the bracing rigidity was achieved. The threshold stiffness of the bracing which is just enough to make frames buckle in a non-sway mode was obtained. Nonlinear analysis of braced frames subjected to combined loads was also made. A criterion was established to judge the buckling mode of braced frames including the effects of horizontal loads. A series of story models and a two-story two-span braced frame were analyzed by finite element model （FEM）. Results showed that the proposed formula is simple, clear and conservative.

关 键 词：支撑框架 弹塑性失稳 临界支撑刚度 

分 类 号：TU323.5[建筑科学—结构工程]