Research On The Mechanical Performance Of Prefabricated Composite Primary And Secondary Beam Nodes Based On New Steel Tongue-and-groove Connection

Assembly frame structure has been widely applied and popularized in our country because of its characteristics of high engineering quality,short construction period,good economic benefits and energy saving and environmental protection.Assembly frame structure connects prefabricated members through nodes,and transmits the axial force,shear force and bending moment of prefabricated members through nodes.Therefore,the connection of prefabricated member joints is the key point that affects the overall performance of assembly frame structure.Prefabricated primary and secondary beam joints are important components of assembly frame joints and play an important role in vertical load transfer.In this paper,two new steel groove joints are proposed,and the mechanical properties of eight specimens with primary and secondary beam joints are studied by monotonic static loading test and finite element simulation.The main research contents and conclusions are as follows:(1)Summarize the shortcomings of the existing prefabricatedt primary and secondary beams concrete post pouring joints and common steel groove joints,and put forward two new steel groove joints,namely stiffened steel groove joints and double steel groove joints,considering the factors of design,production,construction and mechanical performance.On the premise of inheriting the advantages of dry connection and simple construction of common steel groove joints,the two new steel groove joints further strengthen the connection integrity of prefabricated composite primary and secondary beam joints,and have a good application prospect.(2)Design and conduct monotonic static loading tests on 8 specimens of primary and secondary beam joints,including 1 specimen of integral pouring of primary and secondary beam joints,1 specimen of prefabricated composite primary and secondary beam common steel groove joint,3 specimens of prefabricated composite primary and secondary beam reinforced steel groove joint,and 3 specimens of prefabricated composite primary and secondary beam double steel groove joint.Study the crack development and failure modes of each group of specimens under monotonic static loading at the cantilever end of the secondary beam,and compare and analyze the carrying capacity,displacement ductility,and stiffness performance indicators of each group of specimens based on experimental data.The results show that the failure mode of common steel groove joint specimens is the bending failure at the fixed end of secondary beam.The failure modes of the integral pouring joint specimen,the stiffened steel groove joint specimen and the double steel groove joint specimen are similar,which all show the inclined section bending failure within the range of the fixed end of the secondary beam one times the beam height.The carrying capacity of common steel groove joint specimens,stiffened steel groove joint specimens,and double steel groove joint specimens is basically the same,with an error of only 4%.Compared with integral pouring joint,the carrying capacity of all three types of steel groove joints can be increased by about10%.The stiffness order of each group of specimens in the elastic stress stage is: double steel groove joint>stiffened steel groove joint>integral pouring joint>common steel groove joint;The stiffness order of the working stage with cracks is: stiffened steel groove joint>double steel groove joint>common steel groove joint>integral pouring joint.(3)Through ABAQUS finite element software,monotone static loading numerical simulation was carried out on the integral pouring primary and secondary beam joint and prefabricated composite primary and secondary beam steel groove joint model,and the results were compared and analyzed with the test results,and stress distribution of each group of steel grooves during the stress process was mainly studied.The results indicate that the failure mode and load cantilever end deflection curve simulated by the finite element model are in good agreement with the experimental results,verifying the reliability of the model.The stress of the three sets of steel grooves is relatively small in the early stage of loading,and then as the load increases to the ultimate load,the bottom end of the extended groove steel plate of the common steel groove yields;the bottom end of the pre embedded steel plate with stiffened steel grooves yields;the extended groove bolt of the double steel groove yields.In addition,during the entire stress process,the bolt stress of the three groups of steel groove embedded groove steel plates is relatively small.