拉弯组合作用下外伸端板节点受火全过程力学性能有限元分析  

Finite Element Analysis of Mechanical Properties of Extended End-Plate Joints Under the Combined Action of Tension and Bending During the Entire Fire Process

作　　者：高语官 汤轶群 杜二峰[1] Yuguan Gao;Yiqun Tang;Erfeng Du(School of Civil Engineering,Southeast University,Nanjing 210096,China)

机构地区：[1]东南大学土木工程学院,南京210096

出　　处：《钢结构(中英文)》2024年第12期95-102,共8页Steel Construction(Chinese & English)

摘　　要：外伸端板节点在钢结构设计中主要用于传递重力和地震作用。然而,在极限状态下,连接节点还对结构的整体性能及防止连续倒塌具有重要影响。在各种灾害中,火灾仍是发生频率最高、影响范围最广的灾害之一。目前抗火性能研究主要集中于火灾的升温阶段,但材料、构件和结构在降温阶段可能表现出与升温阶段不同的特性。钢节点在火灾全过程中会受到梁跨中大挠度导致的“悬链线效应”所产生的拉力以及钢材的冷缩所产生的拉力影响,在拉弯组合的作用下发生破坏,进而导致钢框架整体结构倒塌。目前,国内外对钢框架外伸端板连接节点在火灾全过程中的力学性能研究较少,因此亟需对其展开深入研究,为性能化防火设计提供技术支持,以保证火灾发生后的一定时间内主要结构构件不发生破坏,建筑内的人员有足够的时间逃生,并使消防人员有合理的救援时间。采用ABAQUS有限元软件对拉弯组合荷载作用下的外伸端板节点进行非线性热力耦合分析。首先,建立外伸端板节点在火灾升温段的三维热分析及结构响应非线性分析模型,利用现有文献中的恒载受弯升温试验结果对该建模方法的准确性进行验证。在此基础上,通过瞬态热分析得出火灾升降温全过程中节点的温度场分布,利用热-结构耦合分析得到节点在拉弯组合荷载作用时的力学性能,并针对火灾升降温历程及拉力荷载大小等因素对节点力学行为的影响进行参数化分析。结果表明,火灾全过程中由于温度滞后的影响,节点的挠度在降温阶段将继续增大,并导致其在降温初期破坏。同时,受悬链线效应和钢梁冷缩变形产生拉力的影响,螺栓受拉对节点的耐火时间和残余变形不利。此外,对节点进行不同拉力的参数分析显示:保持节点弯矩恒定不变时,拉力对节点受力会产生显著影响。当拉力增大时,节点�The extended end-plate joint is mainly used to transfer gravity and seismic effects.However,in extreme states,connecting joints also have a significant impact on the overall performance of the structure and the prevention of continuous collapse.Among various disasters,fire is still one of the disasters with the highest frequency and the widest range of influence.At present,research on fire resistance performance mainly focuses on the heating stage of a fire,but materials,components,and structures may exhibit different characteristics during the cooling stage compared to the heating stage.During the entire process of a fire,steel joints will be subjected to the tension generated by the“catenary effect”caused by the large deflection of the beam span,as well as the tension generated by the cold shrinkage of the steel.Under the combined action of tension and bending,the steel joints will be damaged,leading to the collapse of the entire steel frame structure.At present,there is relatively little research on the mechanical properties of extended endplate joints of steel frames during the entire fire process,both domestically and internationally.Therefore,it is urgent to conduct indepth research on them to provide technical supports for performance-based fire protection design.This ensures that the main structural components are not damaged within a certain period of time after a fire,allowing sufficient time for personnel in the building to escape and for firefighters to carry out their rescue operations.In the present study,nonlinear thermal-mechanical coupling analysis of extended end-plate joints under the combined action of tension and bending was conducted by using the ABAQUS finite element software.Firstly,a three-dimensional thermal analysis and structural response nonlinear analysis model was established for the extended end-plate joint in the fire heating stage.The accuracy of the modeling method was verified by using the results of heating tests under constant bending effect in existing literature.On this

关 键 词：外伸端板节点 火灾全过程 有限元 抗火性能 螺栓连接 

分 类 号：TU391[建筑科学—结构工程] TU352.5