柱顶受轴力的柱列支撑受力分析

Researches on horizontal inter-column bracing forces with braced columns under top axial compressions

采用蒙特卡罗方法,考虑柱子初始缺陷和撑杆初始缺陷的随机遇合问题,应用有限元程序ANSYS对柱顶受轴力的柱列支撑体系进行了大量的仿真分析,得到了柱列纵向支撑体系的两种失稳模式;通过概率统计得到柱中水平撑杆所受内力的双正态概率密度函数,据此确定了可用于实际工程设计的支撑力的大小。结果表明:当柱顶轴力相等时,采用《钢结构设计规范》(GB 50017—2003)中柱列支撑设计公式计算支撑力偏大;当柱顶轴力不等时,采用规范公式计算支撑力将更保守;柱子初始缺陷和撑杆初始缺陷的随机遇合作用导致柱中水平撑杆受压力或拉力的随机性,降低了支撑力。

A large number of column-bracing systems are studied by using ANSYS program when braced columns are under top axial compressions,in which random combination of the initial imperfections between columns and bracing bars is well considered by the Monte Carlo method.According to the analysis results,two kinds of buckling modes of longitudinal bracing system have been found,binormal probability density function of the bracing force is found through probability statistics,and the design bracing force is also obtained.The results show that the above design bracing force is smaller than that proposed by the 'Code for design of steel structures'(GB 50017—2003) with equal axial compressions on the braced columns,and much smaller than the latter with unequal axial compressions on the braced columns.The results also indicate that random combination of the initial imperfections between columns and bracing bars leads to the randomness of horizontal inter-column brace forces in compression or tension,then the design bracing force can be reduced.