Research On Seismic Performance Of Prefabricated Steel Frame Joint Considering The Effect Of Composite Slap

Prefabricated steel frame is a structural system formed by frame columns,beams and composite slap connected,which belongs to the green building.In the seismic damage and engineering accident of steel frame,the damage location mostly occurs in the joint position,which belongs to the most complex region.The prefabricated steel frame adopts the form of full bolt connection,which has the advantages of simple force transmission path and large rotational deformation capacity,so that the bending moment distribution of the structure is more reasonable and the overall deformation capacity and ductility are improved.The composite slap is generally composed of profiled steel-deck and concrete,which can effectively limit the local buckling instability of the steel beam,but restrain the rotation deformation of the joint.Most of the existing studies on steel joints focus on the detail construction of beams,columns and connections,and pay less attention to the impact of composite slap.Therefore,the main research content of this paper is to study the seismic performance of prefabricated steel frame joints composite slap.Based on the cyclic loading test of the end plate connection,the seismic performance analysis and the plastic cracking analysis of the bolt welded joint,the end plate joint and top-seat-angle joint with the combined slap were carried out through theoretical derivation and numerical simulation.Parametric analysis was carried out on the important detailed parameters of the joint,such as composite slap,connector and profiled steel-deck type.1)Three types of steel joints,such as the bolt welded joint,the end plate joint and top-seat-angle joint,are designed and calculated in accordance with the specifications for the theoretical value of bearing capacity at the elastic stage.Three kinds of joints are simulated numerically and the results are extracted.The results show that the combined slab can improve the bearing capacity of the joints in elastic stage by comparing the theoretical values.The thicker the composite slap,the larger the bearing capacity increases,and the end plate connection is the most obvious.In the loading test of end-plate joint,when the load is large,the middle part of the end-plate bulges and the stiffening rib of the end-plate deforms seriously close to failure.The end plate joint has higher energy dissipation capacity and better seismic performance.2)Three types of beam-column joints are modeled and simulated by finite element method.The moment-angle curves are extracted and compared to determine the type of joint stiffness.The seismic performance of the three kinds of joints is studied by sortingand comparing the ultimate bearing capacity,initial rotational stiffness,energy dissipation capacity and maximum angle of the joint region.The results show that the bolt welded joint is close to the rigid connection,top-seat-angle joint is close to the hinge connection,and the end plate joint is a semi-rigid connection.The seismic performance of the bolt welded joint is the best,the end plate joints the second,and the top-seat-angle joint the least.Compared with the maximum angle of the joint region,the top-seat-angle joint is the largest,the bolt welded joint is the smallest,and the end plate joint is between the two.The thickness of the connecting plate has a certain influence on the seismic performance of the bolt welded joint and the end plate joint.When the thickness of the connecting plate increases,its ultimate bearing capacity and initial stiffness are slightly increased.The seismic performance of top-seat-angle joint and end plate joint is improved greatly by stiffening ribs.3)By comparing the moment-angle curves,the action law of composite slap slab on steel frame joints is summarized.The influence of the composite slap thickness and the profiled steel-deck type on the seismic performance of the joint is numerically analyzed.The stress distribution of high strength bolts and shear stud joints and cracks of composite slap of steel frame are analyzed and studied.The results show that the seismic performance of the joint is improved obviously when the combined slap slab is added.After the thickness of the composite slap increases to 120 mm,the composite slap thickness has little influence on the seismic performance of the joint.The earthquake resistant performance of the closed type profiled steel sheet is superior to that of the open type profiled steel sheet.The stress on the shear stud decreases gradually along the bottom of the stud,and the maximum stress on the shear stud increases with the increase of the concrete thickness.The position of concrete plastic damage in the composite slap slab is at the beam-column intersection under the vertical load,and a large area of the middle part of the concrete slap slab is cracking.