厚板柱钢框架梁柱节点对断裂韧性的要求

为了研究厚板柱钢框架梁柱节点对材料断裂韧性的要求，进行了三维弹性和弹塑性断裂力学有限元计算.以裂纹尖端的应力强度因子KI和JI为评价指标，分析了焊接工艺孔形式、梁翼缘削弱或加强和初始裂纹位置等因素对梁柱节点断裂韧性的不同要求.结果表明：美国北岭地震后改进的焊接孔B对断裂韧性的要求最低，而我国《建筑抗震设计规范》规定的焊接孔D对断裂韧性的要求相对较高；与标准型节点相比，梁翼缘削弱或加强型节点能显著降低对断裂韧性的要求；当焊接高匹配时，热影响区裂纹比焊根裂纹更易于扩展，并导致节点的断裂破坏.钢框架梁柱节点断裂评估定量方法为节点防断设计中钢材与焊材的选材、焊接孔与节点形式的选用提供了参考.

Demand of beam-column connection in steel frame with thick plate column on fracture toughness

In order to investigate the demand of beam-column connections in steel frame with thick plate column on the fracture toughness of materials,the finite element calculation of three dimensional(3D) elastic and elastoplastic fracture mechanics was carried out.The stress intensity factor(KI) and J-integral(JI) around crack tip were used as the evaluation indexes,and the different requirements of such factors as the weld access hole form,either weakening or strengthening with beam flange and initial crack location on the fracture toughness of beam-column connections were analyzed.The results show that the weld access hole B improved after Northridge earthquake in USA exhibits the lowest demand on the fracture toughness,while the weld access hole D given by "Code for anti seismic design of buildings" in China shows relatively higher demand on the fracture toughness.Compared with the standard connections,the beam flange weakened or strengthened connection can reduce the demand on the fracture toughness remarkably.With the high weld match,the crack in heat-affected zone is easier to propagate than that in weld root zone,and leads to the fracture failure of the connections.The quantitative evaluation method for the fracture of beam-column connections in steel frame can provide the references for the selection of steel,welding material,weld access hole and connection form in the anti-fracture design of connections.