| In recent years,with the rapid development of the construction industry,the state vigorously promotes the reform of the supply side of the steel structure industry,and the prefabricated steel structure buildings are experiencing a period of historical opportunity of rapid development.Under this background,a steel tube bundle composite shear wall system is proposed,which can be used in residential buildings.The system is a kind of architectural applicability,structural applicability and economic applicability of good structural system,has good bearing capacity,earthquake resistance,can be flexible with the change of building function layout,and the cost is low,is a reasonable form of building structure.The connection between the steel tube bundle shear wall and the H-shaped steel beam is the key part of the steel tube bundle composite shear wall system.In view of the improvement of the existing steel tube bundle composite shear wall-beam connection node,this paper proposes a new type of steel tube bundle composite shear wall unilateral high-strength bolt end plate connection node,which can realize assembly construction.It avoids the complicated production process and avoids the adverse effect of welding connection on the mechanical performance of the node.In this paper,through the numerical simulation analysis of the steel tube bundle composite shear wall-beam point connected by domestic single-sided high-strength bolts,the mechanical characteristics of the joint are studied and analyzed.Before the finite element analysis of the joint,the monotonic pull-out test of the single-sided high-strength bolt connection of the steel tube bundle at the key force transmission part of the joint was carried out.Four groups of specimens were designed.The effects of end plate thickness and steel tube bundle thickness on the failure mode,bearing capacity and initial tensile stiffness of the single-sided high-strength bolt connection of the steel tube bundle were studied,and compared with the experimental results of the ordinary high-strength bolt connection of the steel tube bundle.The finite element modeling and parametric analysis of the unilateral high-strength bolt connection of the steel tube bundle are carried out to enrich the experimental data,and the initial tensile stiffness formula of the unilateral high-strength bolt connection of the steel tube bundle is derived.The research results are as follows :(1)The single-side high-strength bolt connection of steel tube bundle can realize the unilateral connection and fastening of steel tube bundle and end plate.It has the advantages of simple construction,reliable connection,high bearing capacity and good plastic deformation ability.(2)The diameter change of unilateral high-strength bolt can significantly affect the failure mode of the joint.When the diameter of the bolt is less than 20 mm,the joint model is finally damaged due to the breakage of the unilateral high-strength bolt.The pinch phenomenon of the hysteresis curve of the joint is serious,and the bearing capacity,rotational stiffness and ductility are poor.When the bolt diameter is greater than or equal to 20 mm,the concrete of the steel tube bundle is destroyed,the deformation of the outer sleeve is serious,and the joint is finally destroyed due to the pull-out of the unilateral high-strength bolt.The hysteretic curve of the joint is fuller than that of the former,and the bearing capacity and seismic index are improved to a certain extent,but the excessive diameter of the bolt will lead to the decrease of the ultimate rotation angle and the decrease of the ductility performance.(3)In the connection between steel tube bundle and end plate,although the ultimate bearing capacity and plastic deformation capacity of ordinary high strength bolt connection of steel tube bundle are greater than that of unilateral high strength bolt connection,it is necessary to reserve the installation hand hole in the actual project,which is not only inconvenient for construction,but also can not avoid the adverse effect of welding connection on cold-formed thin-walled steel tube.(4)The numerical simulation results of finite element analysis of unilateral highstrength bolted connection of steel tube bundles are in good agreement with the experimental results,which verifies the reliability of the modeling method.At the same time,the influence of end plate thickness and steel tube bundle thickness on the connection performance was further verified by parametric modeling.(5)The initial tensile stiffness formula of unilateral high-strength bolt connection of steel tube bundle is derived by component method.The theoretical value is in good agreement with the finite element parametric analysis results,and the initial tensile stiffness formula has good reliability.The finite element model of the single-sided high-strength bolted end-plate connection of the steel tube bundle composite shear wall was established by using the finite software ABAQUS.By changing the thickness of the end plate,the diameter of the single-sided high-strength bolt,and the setting of the local reinforcement plate,a total of9 finite element models were established.The seismic performance of the joints was studied,and the influence of the above structural parameters on the wall-beam connection joints was analyzed.The results are as follows :(1)The thickness of the end plate has no obvious influence on the failure mode,bearing capacity,rotational stiffness and seismic performance of the joint.The bolt is pulled out from the concrete of the steel tube bundle due to the bending of the wall of the steel tube and the bending of the outer casing of the unilateral high-strength bolt,resulting in the failure of the specimen.The slippage of single-side high-strength bolts in steel tubular concrete is obvious,which causes the bending moment-angle curve to shrink.(2)The diameter change of the unilateral high-strength bolt can significantly affect the failure mode of the joint.When the bolt diameter is less than 20 mm,the joint model is finally damaged due to the breakage of the unilateral high-strength bolt.The joint is brittle failure,and the hysteresis curve of the joint is pinched seriously and the mechanical properties are poor.When the bolt diameter is greater than or equal to 20 mm,the joint eventually loses its bearing capacity because the unilateral high-strength bolt is pulled out.The hysteresis curve is fuller than the former,and the mechanical properties and deformation capacity are improved.(3)Setting up local strengthening plates can improve the stiffness of the steel tube bundle concrete in the core area of the node,thereby reducing the slip of the high-strength bolt on one side.The failure mode of the node is that the outer casing of the high-strength bolt on one side is pulled apart.Compared to nodes without local reinforcement plates,the hysteresis curve of this type of node is full,and the deformation performance and energy dissipation capacity of the node are improved to varying degrees. |
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