钢框架节点焊缝应力强度因子的参数分析

Parametric studies of stress intensity factors with varied steel frame connection geometry

为定量地确定荷载作用下钢框架梁柱节点焊缝应力强度因子的大小,提出了断裂力学与有限元分析相结合的方法.有限元分析采用ANSYS软件.判断焊缝开裂的依据是Ⅰ型应力强度因子,应力强度因子通过积分的方法求得.通过有限元计算分析了初始裂缝深度对梁柱节点焊缝应力强度因子的影响,所分析的参数还包括梁截面尺寸、柱截面尺寸、梁柱长度和焊脚尺寸.分别研究了梁上翼缘和下翼缘焊缝的应力强度因子随参数的变化情况.参数分析结果表明,梁下翼缘焊缝比上翼缘更容易开裂,应力强度因子与梁截面参数是增函数关系,与柱截面参数是减函数关系.最后,得出了应力强度因子计算公式.

A method combining fracture mechanics and finite element analysis was presented to quantify the variation of stress intensity factor to weld root flaw sizes in steel frame connections. Finite element analysis was performed using the ANSYS computer program. Fracture toughness demands were evaluated in terms of mode I stress intensity factor. Stress intensity factor was calculated through a J-integral approach. The connection geometry was separately investigated in terms of the beam and column properties, The influences of beam length, column length and weld leg size on the stress intensity factor were analyzed. The fracture toughness demands for the flaw on the top of the beam flange and for the bottom surface were respectively studied. Results showed that the panel zone deformation has great effect on the stress intensity factor. The likelihood of top flange fractures is smaller than that of bottom flange fracture. Stress intensity factor increases with the increase of beam parameters, and decreases with the increase of column parameters. Finally, formulas for stress intensity factors are deduced.