Study on Single Side High Strength Bolt Connection Performance of Steel Pipe Bundle Composite Shear Wall Endplate Joints

In order to study the ultimate bearing capacity and failure mode of single side high strength bolt connection of steel pipe bundle, the monotone drawing test and finite element numerical simulation of single side high strength bolt connection of steel pipe bundle were carried out, and the influence of end plate thickness and steel pipe bundle thickness on the connection bearing capacity and failure mode was analyzed. Based on the test results and finite element parametric analysis results, the theoretical formula of initial tensile stiffness for single side high strength bolt connection of steel pipe bundle is derived. Firstly, by changing the thickness of the end plate, the thickness of the steel tube bundle and the type of the bolt, 5 steel tube bundle single side high strength bolt connection specimens were designed and made for the monotonic drawing test. Moreover, in order to make the test results biased to the safety, specimens were without filling concrete, and the beneficial effect of concrete was not considered. Secondly, the finite element numerical simulation is carried out on the single side high strength bolt connection of the steel pipe bundle, and the finite element simulation results are compared with the test results to verify the correctness of the finite element modeling method, and the same modeling method is used to carry out parametric analysis on the single side high strength bolt connection of the steel pipe bundle. The influence of tube bundle thickness and end plate thickness on mechanical properties of single side high strength bolt connection of tube bundle was further investigated. Finally, according to the test results and finite element parametric analysis results, the initial tensile stiffness formula of steel pipe bundle single side high strength bolt connection was derived by component method. The theoretical data was compared with the finite element simulation results to verify the accuracy of the formula. The results show that the failure mode of single side high strength bolt connection of steel pipe bundle is as follows: steel pipe bundle bulging, plastic deformation of bolt hole, bending of the outer sleeve of single side high strength bolt leading to the removal of single side high strength bolt, which is different from the failure mode that bolt hole of ordinary high strength bolt connection of steel pipe bundle is broken. Increasing the thickness of steel pipe bundle can significantly improve the bearing capacity and initial tensile stiffness of single side high strength bolt connection of steel pipe bundle. Although the bearing capacity and plastic deformation capacity of single side high strength bolt connection are lower than those of ordinary high strength bolt connection, there is no need to reserve installation hand holes during installation, so as to avoid the adverse effects of welding construction on the mechanical properties of cold-formed thin-wall steel. The finite element numerical simulation results are consistent with the experimental results, which proves that the finite element modeling method is reliable, and the parametric analysis results further show that the mechanical properties of steel pipe bundle single side high strength bolt are mainly controlled by the thickness of steel pipe bundle, but are less affected by the thickness of end plate. The theoretical stiffness derived from the initial tensile stiffness formula of steel tube bundle single side high strength bolt connection by component method is in good agreement with the finite element parameter analysis results, which proves that the initial tensile stiffness formula of steel tube bundle single side high strength bolt connection has good reliability.