Study On Seismic Behavior Of Concrete Filled Steel Tube With Superimposed Shear Wall Out Of Plane

Shear wall is an important lateral component and load-bearing component in the building structure system.With the rapid development of prefabricated building and new building industrialization in China,the transformation and upgrading of the construction industry is inevitable,which also puts forward higher requirements for shear wall structures.This article proposes a new type of Concrete Filled Steel Tube with Superposed Shear Wall(referred to as CFST-SSW),which consists of two parts:a steel tube and a concrete composite shear wall.The steel tube and the composite shear wall are connected by shear bolts;The seismic performance of CFST-SSW walls was studied through quasi-static loading tests,and a systematic parameter analysis was conducted using OpenSees software.The theoretical calculation formula for peak bearing capacity was derived.This article designs and produces 5 CFST-SSW specimens and 1 cast-in-place concrete column composite shear wall specimen.Through out of plane quasi-static tests,the effects of end column type,axial compression ratio,and loading system on the seismic performance of CFST-SSW walls are analyzed.The experimental results show that the out of plane seismic performance of CFST-SSW walls is superior to that of cast-in-place concrete column composite shear wall specimens;As the axial compression ratio continues to increase,the seismic performance of CFST-SSW walls,such as yield bearing capacity,peak bearing capacity,strength,stiffness,and energy dissipation capacity,has significantly improved;The out of plane seismic performance of CFST-SSW walls varies under different loading methods.Using the finite element analysis software OpenSees,a CFST-SSW wall finite element model was established and simulated for analysis.The comparison between simulation results and experimental results shows that the finite element model can accurately simulate the hysteresis curve and skeleton curve of CFST-SSW walls.The error between the simulated average value of peak bearing capacity and the experimental value is within 10%,indicating that the model has sufficient accuracy and rationality.On the basis of the finite element model,the four parameters of CFST-SSW wall,namely steel pipe steel strength,concrete strength,steel pipe wall thickness,and column wall ratio,were analyzed.The parameter analysis results indicate that as the strength of the steel increases,the peak bearing capacity of the CFST-SSW wall increases,but the pinching effect of its hysteresis curve strengthens and the cumulative energy dissipation capacity weakens;The impact of concrete strength on the seismic performance of CFST-SSW wall exterior is relatively small.As the compressive strength of concrete increases,the peak bearing capacity of CFST-SSW wall slightly increases,the hysteresis curve becomes fuller,and the cumulative energy consumption capacity increases;With the increase of steel pipe wall thickness and column to wall ratio,the peak bearing capacity of CFST-SSW walls has been significantly improved,the hysteresis loop area has increased,the cumulative energy dissipation capacity has been enhanced,and the out of plane seismic performance has been enhanced.Further derive the calculation formula for the peak bearing capacity of CFST-SSW walls based on current specifications,and compare the calculation results with the experimental results.The error between the calculated value of the peak bearing capacity and the experimental value is within 10%,indicating that this calculation formula can accurately calculate the peak bearing capacity of CFST-SSW walls.