钢框架梁柱栓焊混合连接计算方法的探讨

Discussion on calculation method of beam-column welded-bolted hybrid connection of steel frame

翼缘焊接腹板栓接的梁柱栓焊混合刚性节点是钢框架梁柱现场连接的主要形式之一,该节点需满足“强节点”的设计原则。传统的栓焊混合节点计算仅考虑翼缘抗弯和腹板抗剪,《高层民用建筑钢结构设计规范》(JGJ 99—2015)借鉴日本规范,给出了钢梁腹板承担梁端弯矩的计算方法。基于常用的热轧型钢截面,对比了考虑翼缘与腹板均参与抗弯的栓焊节点新算法与仅考虑翼缘抗弯的传统算法之间的差别。结果表明:腹板对梁柱节点的极限抗弯承载力提高有限,腹板抗弯承载力占梁柱连接的极限抗弯承载力的比值为8%~14%;对常用HN型钢,即便考虑腹板抗弯,仍然无法满足《高层民用建筑钢结构技术规程》(JGJ 99—2015)公式(8.2.1-1)Mj u≥αMp,还需要采用加强型连接或狗骨式节点。由于腹板螺栓的抗弯中心距明显小于翼缘的抗弯中心距,用腹板螺栓抗弯不太经济。腹板配置受弯螺栓数量远超抗剪所需螺栓,并造成连接板尺寸过大,相比单纯加强翼缘反而更浪费材料。梁柱节点需进行小震弹性和极限承载力的两阶段设计,实际工程案例表明,跨高比较大的钢梁腹板螺栓一般由弹性设计控制,跨高比较小时由极限承载力控制。

The beam-column welded-bolted hybrid rigid joint with flange welded and web bolted is one of the main forms of field connection of steel frame beam-column.This joint must meet the design principle of“strong connection”.The calculation of traditional welded-bolted hybrid joints only considers flange bending resistance and web shear resistance.The Technical specification for steel structure of tall building(JGJ 99—2015)draws on Japanese standards and gives the calculation method of steel beam webs to bear the beam end bending moment.Based on commonly used hot rolled HN steel sections,the difference between the new algorithm for welded-bolted joint that considers both flange and web to be involved in bending resistance and the traditional algorithm that only considers flange bending resistance was compared.The results show that the ultimate bending capacity of the web to the beam-column joint is limited,and the ratio of the bending capacity of the web to the ultimate bending capacity of the beam-column joint is 8%~14%.For commonly used HN steel section,even considering the bending resistance of the web,it still cannot meet the formula(8.2.1-1)Mj u≥αMp in the Technical specification for steel structure of tall building(JGJ 99—2015).It is necessary to use strengthened connections or reducedbeam section joint.Since the bending center distance of the web bolts is significantly smaller than the bending center distance of the flange,it is not economical to use web bolts to resist bending.The number of bending bolts of the webs far exceed the bolts required for shear resistance,and the size of the connecting plate is too large,which wastes more material than simply strengthening the flange.The beam-column joint needs to be designed in two stages of seismic elasticity and ultimate bearing capacity.Actual engineering cases show that the web bolts of steel beams with relatively large spans are generally controlled by elastic design,and those with relatively small span are controlled by ultimate bearing capacity.