钢—混组合桁架节点处PBL剪力键群受力性能研究

Mechanical Behaviors of PBL Shear Connector Group at Steel-Concrete Composite Truss Joints

采用有限元分析软件ABAQUS建立整体耳板式、分离耳板式和外接式3种钢—混组合桁架节点的简化模型,计算1倍、2倍、3倍设计荷载作用下各类型节点处PBL剪力键的水平和竖向滑移,然后根据单根PBL剪力键的荷载—滑移关系反推PBL剪力键的负载,进而研究PBL剪力键群的负载分布规律及其受力性能。结果表明:节点处同行PBL剪力键的水平负载分布呈"不平衡对称"模式,竖向负载分布呈"反对称"模式,PBL剪力键群的负载以水平方向为主,且荷载中心线与PBL剪力键群中心线不重合是导致PBL剪力键群水平负载不均匀程度增加的主要原因;随荷载的增加,PBL剪力键群的水平负载最终趋于相对均匀,而其竖向负载的不均匀性无明显变化;依据工程要求,提出将单根剪力键负载控制在其弹性极限荷载内或在0.576倍极限承载力内的校核方法,以保证疲劳破坏不从剪力键群开始或疲劳寿命在200万次以上的设计要求,据此对3种类型节点处PBL剪力键群的校核结果表明,其强度和疲劳性能均能满足要求;整体耳板式节点的强度储备最大,外接式次之,分离耳板式最小。

Three types of simplified models for steel-concrete composite truss joints,namely,integral ear plate joint,separate ear plate joint and external joint,were built by FEA software ABAQUS.The horizontal and vertical slip of PBL shear connector at each type of joint was worked out under 1,2and 3times design load.Then based on the load-slip relationship of single PBL shear connector,the load of PBL shear connector was inversely calculated to further study the load distribution law and the mechanical behaviors of PBL shear connector group.Results indicate that the distribution of the horizontal load of PBL shear connectors in the same line at the joint shows＂unbalanced symmetry＂while the vertical load shows＂antisymmetry＂.The load of PBL shear connector group is mainly in horizontal direction.The misalignment of the center lines of the load and PBL shear connector group is the main factor that leads to the increase in the uneven degree of the horizontal load of PBL shear connector group.With the increase of load,the horizontal load of PBL shear connector group tends to be relatively even finally,while the uneven degree of vertical load doesnt change significantly.A check method is proposed,which prescribes the load of single PBL shear connector below its elastic ultimate load or below 0.576 times ultimate bearing capacity according to engineering requirement,in order to guarantee the design requirements that the fatigue failure does not initiate from PBL shear connector group or the fatigue life is more than 2 million times.Accordingly,the PBL shear connector groups at three types of joints have been checked and the results show that both the strength and fatigue performance meet requirements.Integral ear plate joint has the maximum margin of strength,external joint the second and separate ear plate joint the least.