Research And Design Calculation On Seismic Behavior Of Steel Tube Bundle-concrete Composite Shear Wall

The steel tube bundle concrete composite shear wall is a steel-concrete composite shear wall made by welding square steel tubes and U-shaped steel tubes and pouring concrete into the steel tubes.As the main lateral force-resistant component of the structure,it not only has high bearing capacity and good seismic performance,but also can realize modular design,factory production and assembly construction.On the basis of the test,this paper compares and analyzes the mechanical properties and influencing factors of the steel tube bundled concrete composite shear wall,and proposes the restoring force model and model parameters of the low-cycle repeated load.According to the restoring force model,the hysteresis curve is drawn,and the test curve is checked and analyzed,and the design methods and suggestions such as the calculation formula of bearing capacity and the calculation formula of stiffness are put forward.The main research contents and conclusions are as follows:（1）Taking the axial compression ratio,shear-span ratio and steel tube bundle steel plate thickness as parameters,the low-cycle repeated load performance of the steel tube bundle concrete composite shear wall was experimentally studied.On the basis of experimental research,the effects of axial compression ratio,shear-span ratio,steel content and other indicators on the wall failure form,bearing capacity,stiffness,ductility and energy dissipation capacity are analyzed.The results show that although the steel tube bundle concrete composite shear wall has good hysteretic performance,parameters such as shearspan ratio,axial compression ratio,and steel content have a significant effect on its performance.（2）The effects of axial compression ratio,shear-span ratio and steel content on the mechanical properties of steel tube bundle concrete composite shear walls are mainly reflected in the stress and buckling failure of steel tube bundles at the end of the shear wall.In the case of different shear-span ratio,axial compression ratio and steel content,the horizontal load and deformation of the wall when the end steel tube bundle buckling failure is different,which directly determines the hysteretic performance of the wall.The buckling of the end steel tube bundle is theoretically analyzed,and the width-thickness ratio and length-width ratio of the tube wall of the end steel tube bundle without buckling are calculated.The failure mechanism of the steel tube bundle concrete composite shear wall is further expounded,which provides a theoretical basis for the design of the tube bundle size and tube wall thickness of the steel tube bundle shear wall.（3）Based on the analysis of the low-cycle repeated load test results,the strip method is used to analyze the bearing capacity of the normal section of the shear wall,and the simplified calculation formula is summarized.After comparison and checking,the calculated results are in good agreement with the test results,which can be used for the calculation of the design bearing capacity.The calculation formula of bearing capacity also provides a method and basis for the calculation of parameters in the restoring force model of steel tube bundled concrete composite shear wall.（4）According to the hysteresis curve and skeleton curve of the steel tube bundle concrete composite shear wall,the stress characteristics of the shear wall during loading,unloading and reverse loading,the characteristic points of horizontal force and deformation,and the stiffness of each stage are analyzed.The restoring force model and model parameters of composite shear wall of steel tube bundled concrete are proposed,and the hysteresis curve is calculated by using the proposed restoring force model and its parameters,which is compared with the test curve.The results show a good degree of agreement,indicating that the proposed restoring force model can be used for elastoplastic analysis of actual structures.