考虑节点损伤的钢框架结构分析模型

钢框架结构在强震作用下将进入非线性状态,结构的刚度和强度等力学性能随之降低,从而影响到结构以后的抗震性能.本文利用断裂力学的基本原理,通过对栓焊节点存在焊缝裂纹的钢框架刚性连接节点的分析,推导了裂纹的有效长度和有效深度,获得了有损伤刚性连接节点的M-θ关系;并推导了节点有损伤的梁单元刚度矩阵.在数值计算的基础上分析了节点刚度变化对框架结构内力的影响,结果表明节点损伤对结构内力分析影响显著,对有损伤钢框架结构进行承载力评估时必须考虑节点损伤的影响.

Computation model of the steel frames with joint damages

Steel frame structure will be in nonlinear state under strong earthquake with its mechanic properties of stiffness and strength degraded. This degradation has significant effect on seismic performance of structure later on. Based on the fracture mechanics, the behavior of the bolt-seam joints with cracks in welding seams of the steel frames are analyzed in this paper. The effective length and effective depth of a crack are derived. The relationship between bending moment (M) and rotation (θ) of the damaged rigid connection is obtained. The stiffness matrix of a beam with damaged joints is also derived. Numerical analysis is also conducted to ascertain the effects of joint stiffness on the internal forces of damaged steel frames. The results show that the joint damage has significant effects on the internal forces of the frames. Therefore, joint damage must be taken into account to ascertain the load bearing capacity of steel frames.