火灾中采用逆向通道连接的钢梁-钢管混凝土柱结构约束组件的数值模拟

利用有限元软件ABAQUS,采用三维块单元,模拟火灾中钢梁-钢管混凝土柱及其节点约束组件的性能。利用近期英国曼彻斯特大学的采用逆向通道连接的3组耐火试验,对模型进行验证。结果表明:有限元模型能成功进行模拟。利用有限元模型,初步研究改变连接构件以加强结构耐火能力的可行性。对连接方式进行改进,以期使连接梁的链式反应能更好发展。提出外伸-内缩式混合端板连接形式,连接的拉伸部分采用外伸端板,以提高延性;受压部分采用内缩式端板,提高韧性。结果表明:不需任何费用,只要用混合端板连接替代外伸端板连接,就能提高连接梁的耐火能力。

Numerical Modelling of Restrained Structural Subassemblies of Steel Beam and CFT Columns Connected Using Reverse Channels in Fire

This paper employs the general finite element software ABAQUS to numerically model the behaviour of restrained structural subassemblies of steel beam to concrete filled tubular(CFT) columns and their joints in fire.The simulations were conducted using 3-D brick elements to enable detailed structural behaviour to be obtained.For validation,this paper compares the simulation and test results for the three fire tests using reverse channel connection recently conducted at the University of Manchester.This comparison demonstrates that the 3-D finite element model is able to successfully simulate the fire tests.Afterwards,the validated finite element model was used to conduct a preliminary numerical study to investigate the feasibility of changing some of the connection details to enhance survivability of the structure in fire.Specifically,this investigation concentrated on developing connection methods to enable catenary action in the connected beam to be more fully developed.An example is to develop a hybrid flush/extended endplate and flexible endplate connection in which the tension part of the connection uses a flush/extended endplate for increased tensile resistance but the compression part of the connection uses a flexible endplate for improved ductility.It has been found that,without additional cost,using a hybrid extended/flexible endplate connection to replace a flush endplate connection has the potential to enable the connected beam to survive significantly increased temperature.