钢框架加强型梁柱节点子结构的抗冲击性能试验研究

设计了采用FEMA 350过焊孔构造的1个普通栓焊连接和2个加强型（盖板和翼缘加强型）栓焊连接的钢框架梁柱节点子结构试件，对试件进行落锤冲击来模拟结构的动态倒塌过程，考察栓焊节点加强方式对钢框架梁柱节点抗冲击性能的影响。通过试验获得节点试件的破坏形态及其冲击作用和位移时程曲线，分析试件冲击作用和位移时程响应规律以及子结构动态转角和耗能变化趋势。试验结果表明：节点试件的主要破坏形态是显著整体弯曲变形和钢梁上翼缘塑性铰截面附近处受压屈曲，采用FEMA 350标准过焊孔构造的节点试件具有良好的抗冲击转动能力，3个试件的极限转角均达到了FEMA 350规范抗震设计的转角限值（普通栓焊节点为θ=0.054 rad、加强型节点为 θ=0.070 rad）要求；改进后的盖板加强型和翼缘加强型节点试件的抗冲击能力均得到显著提高，优于普通栓焊节点。通过分析冲击过程中试件截面内力发展规律可知，由于节点过早破坏，限制了悬链线效应的形成，所有试件最终还处于塑性受弯向悬链线发展阶段。

Experimental study on impact behavior of strengthened beam-column connections of steel frames

One ordinary bolt-welded beam-column connection specimen and two reinforced (cover plate reinforced and flange plate reinforced) bolt-welded beam-column connection specimens of steel frame with FEMA 350 weld access hole were designed based on the Chinese seismic code and relevant references. The impact tests using drop-hammer were carried out to simulate the dynamic behavior of structural progressive collapse. The influence of reinforcing methods for the beam-column connection on the impact resistance of steel frame substructure was investigated. The failure modes and time histories of impact load and deformation were obtained, and the dynamic responses of the impact load and deformation time histories were analyzed as well as the dynamic rotation and energy dissipation of the substructures. Test results show that bolt-welded beam-column connection specimens fail mainly due to the remarkable global bending deformation and local buckling of steel beam flange near the plastic hinge section. The specimens with FEMA 350 weld access hole have good rotation capacity to resist impact loading, while its ultimate rotation is not less than the FEMA 350 design limit (ordinary bolt welded connection: θ=0.054rad, improved bolt-welded connection: θ=0.070 rad). The impact resistance of strengthened connection specimens is improved significantly, which is better than that of ordinary bolt-welded connection. The internal force development of specimens during the impact loading was analyzed. It is demonstrated that the premature failure of the bolt-welded beam-column connection degrades the formation of catenary action. The ultimate state of specimens were still in the development stage from plastic bending status to the formation of catenary action.