工业化装配式高层钢结构桁架梁腹杆计算长度分析

EFFECTIVE LENGTH ANALYSIS OF TRUSS BEAM WEB MEMBER OF INDUSTRIAL PREFABRICATED HIGH-RISE STEEL STRUCTURE

新型工业化装配式高层钢结构桁架梁不同于传统形式的桁架梁,需将其简化成单根腹杆和弦杆进行稳定验算,并用计算长度来体现结构其他部分的约束作用,但GB 50017—2003《钢结构设计规范》对桁架梁腹杆计算长度的规定比较保守。基于刚架弹性稳定理论以及相关研究成果建立的四弯矩方程,综合考虑桁架梁的上、下弦杆刚度和节点刚度对腹杆计算长度的影响,推导出杆件群的稳定方程以及腹杆计算长度系数的计算方程。通过MATLAB编程解超越方程,列出了可供工程设计使用的桁架梁腹杆计算长度系数用表。针对节点实际刚度与计算刚度不一致的现象,推导了腹杆-弦杆半刚性节点刚度与节点弯矩关系的解析公式,求出节点刚度,便于设计人员查表得到相应计算长度系数。

The truss beam of new industrial prefabricated high-rise steel structure is different from the traditional one.For the stability calculation,it is needed to separate the truss beam into web member and chord member. And the effective length is used to be a constraint from other parts for the member. The value for the effective length of truss beam web member given by Code for Design of Steel Structures( GB 50017- 2003) is relatively conservative.According to the four-moment equation which was based on the classical elastic stability theory of framework and related research results,considering the influence of the upper and bottom chords and the joint stiffness on the effective length of web member,this paper can obtain the stability equations of member group in order to calculate the coefficient for effective length of web member. Solving transcendental equation by using the MATLAB programming,coefficient for effective length of truss beam web member tables are proposed for practical design purpose. In view of the inconformity of the actual joint stiffness and calculative joint stiffness,the paper deduces analytical formula of relationship between semi-rigid joint stiffness and joint bending moment to solve the joint stiffness. Therefore the tables will be convenient for the designers to check the corresponding effective length.