Research On Progressive Collapse Resistance Of Single-layer Cylindrical Latticed Shells With AH Joints

Large span space structure is widely used because of its light and graceful shape.However,the bearing capacity and redundancy of single-layer latticed shell are relatively low,and it is easy to occur progressive collapse accidents,which pose a serious threat to public safety.The progressive collapse-resisting capacity(PCRC)has gradually become an essential requirement in the design of spatial structures.In this paper,the progressive collapse test and numerical simulation of a singlelayer cylindrical latticed shell with type II AH joints were conducted to evaluate the influence of the joint stiffness on the PCRC of fabricated single-layer latticed shells.A combined spring model was established to simulate the semi-rigid performance of fabricated joints in the FEA.The failure mechanism of single-layer cylindrical latticed shells with AH-II joint systems was discussed thoroughly from the member stress,joint displacement and strain energy.The results show that the combined spring model is able to accurately simulate the progressive collapse of a single-layer latticed shell with semi-rigid joints.The progressive collapse of the cylindrical latticed shell with type II AH joints showed brittle features during the test.Most joints experienced connection failure.Compared with AH-II joints,the bearing capacity and stiffness of AH-I joints are mainly determined by the hub,which is easily affected by the coupled action of multidirection loads.In this paper,the FE model of the AH joint is established,and the influence of multi-directional force on the mechanical properties of the AH joint under the action of axial force,bending moment and axial force and bending moment is studied,and the multi-directional stress stiffness and bearing capacity reduction factor of the AH-I joint are obtained.Finally,the spring combination model was modified by the above coefficients,and the PCRC of single-layer cylindrical reticulated shells was carried out.The influences of the joint type,joint stiffness,number of connecting member and other parameters on the PCRC of single-layer cylindrical reticulated shells were analyzed.Although the PCRC of latticed shell with type I AH joints are much lower,it has better ductility during progressive collapse.In this paper,the progressive collapse failure mode of single-layer cylindrical latticed shell with AH joints and the influence of joint stiffness on the progressive collapse resistance of single-layer cylindrical latticed shell are analyzed from the two aspects of test research and FE analysis,which provides a reference for the progressive collapse resistance design of assembled hollow hub Reticulated shell.