梁-H型柱弱轴刚性拼接的子结构抗倒塌性能试验研究

梁柱连接节点是框架结构的重要组成部分，明确节点的受力性能是准确进行结构抗连续倒塌分析的前提。本文基于替代荷载路径法并考虑楼板的组合效应，以两跨三柱型组合梁-柱子结构为研究对象，设计制作了H型柱弱轴方向刚性拼接的栓焊连接、全螺栓连接子结构试件并命名为RWUF、RWUT。对子结构试件进行单调静力加载试验并对比了破坏模式、变形性能和抗力机理。结果表明：试件的加载过程均经历了弹性阶段、压拱阶段、混合机制阶段（梁机制与悬链线机制的混合阶段），且子结构试件首次断裂均发生在混合机制阶段，悬链线效应的发挥为断后荷载的提升起到有利作用；试件的断裂均发生在梁段拼接处，弱轴栓焊连接试件在正弯矩区受拉侧焊缝断裂后破坏持续向腹板扩展直至丧失承载力，弱轴全螺栓连接试件的破坏仅为正弯矩区受拉侧盖板的断裂；螺栓发生有限滑移后，螺栓孔壁持续受到挤压发生轴向变形有利于塑性铰的转动，也为轴力的传递提供了路径，结构受荷后期悬链线效应显著，整体抗力得到提升；基于能量平衡原理对子结构进行动力评估可知，节点的非线性转动能力直接影响了结构的抗倒塌能力，弱轴采用全螺栓连接的结构具备更高的动力倒塌抗力。

Experimental Research on Collapse Resistance of Substructure with Rigid Splicing Connections in Minor Axis

Beam-column connections are an important part of frame structures. The premise of the analysis of anti-collapse performance of structures is to clarify the mechanical properties of the connections. Based on the alternative load path method and considering the combined effect of the floor slab, the failure mode, mechanical property and resistance mechanism of the composite beam-column substructure with rigid splicing connections in minor axis were compared and investigated under the failure of middle column. The composite beam-column substructure named RWUF and RWUT in minor-axis were selected to conduct monotonic static loading test. The results indicate that the two specimens have gone through the elastic stage, compressive arching stage and the mixed mechanism stage (flexure-catenary mixed stage). The first fracture of the specimens occurred in the mixed mechanism stage, and the catenary effect played a favorable role in the increase of the load after fracture. The fractures of the specimens occurred at the splicing point. The cracks at the tension flange of the steel beam of the specimen RWUF in the positive bending moment area continue expanding to the web until it is completely destroyed. Damage of specimen RWUT is only the fracture of the tension cover plate in the positive bending moment area. After the limited slipping of bolts, the axial deformation is continuously accumulated because of the extrusion of bolt holes. It is conducive to the rotation of the plastic hinge, and also provides a path for the transmission of the axial force. The catenary effect is significant in the later stage, and the overall resistance is improved. The dynamic evaluation of the substructure based on the principle of energy balance shows that the nonlinear rotation ability of the connection directly affects the collapse resistance of the structure. In minor axis, the structure with connection that web and flange are united by bolts has a higher dynamic collapse resistance.