高强钢梁柱外伸式端板节点常温与火灾后性能参数分析

Parametric Study on Performance of High-strength Steel Beam-to-column Extended Endplate Connections at Ambient Temperature and after Fire

为了解端板厚度、螺栓直径、螺栓预紧力、柱翼缘厚度、端板钢材强度及过火温度等因素对高强钢端板连接节点力学性能的影响,对薄高强钢端板替代厚普通钢端板这一设计理念进行深入探讨,采用ABAQUS对高强钢端板连接节点进行有限元分析.有限元分析结果表明:端板厚度增加,节点的初始转动刚度和极限承载力提高,转动能力下降;螺栓直径增加,节点的初始转动刚度、极限承载力及转动能力均提高;螺栓预紧力增加,节点的初始转动刚度提高,极限承载力和转动能力基本不变;柱翼缘厚度增加,节点的初始转动刚度提高,极限承载力基本不变,转动能力略有减小;端板钢材强度增加,节点的初始刚度基本不变,极限承载力提高,转动能力在端板钢材强度不超过Q460时基本不变,高于Q460后显著减小;与采用较厚普通钢端板的节点相比,采用薄高强钢端板的节点常温下和火灾后均可达到相似的承载力、相近甚至更高的转动能力;端板连接节点火灾后可能发生失效模式转变,甚至由延性转变为脆性的失效模式.

In order to understand the effects of endplate thickness,bolt diameter,bolt pretension,thickness of column flange,steel grade of endplate and fire temperatures on the behavior of high-strength steel beam-to-column endplate connections,a design concept that thin high-strength steel plate is used to replace the general thick steel plate is deeply discussed,and this paper presents a parametric analysis by using finite element modeling.The results presented herein show that with the increase of the endplate thickness,the initial rotation stiffness and peak moment increase,but the rotation capacity decreases.With the increase of the bolt diameter,the initial rotation stiffness,peak moment and rotation capacity increase.With the increase of the bolt pretension,the initial rotation stiffness increase,but no difference of the peak moment and rotation capacity occurs.With the increase of the column flange thickness,the initial rotation stiffness decrease,but the peak moment has no difference and the rotation capacity slightly decreases.With the increase of the steel grade of the endplate,the initial rotation stiffness remains,the peak moment increases and the rotation capacity remains when the steel grade of the endplate doesn＇t exceed Q460,while the rotation capacity decreases observably when the steel grade of endplate exceeds Q460.A proper design using a thinner high-strength steel endplate can achieve the similar load-bearing capacity and comparable or even higher rotation capacity,in comparison to a connection with thicker mild steel endplate,no matter at ambient temperature or after fire.Further,the failure mode of the endplate connections may be changed after fire,even from a ductile failure mode to a brittle failure mode.