Research On Seismic Behavior Of Prefabricated Cold-Formed Steel "Frame-Wall" Composite Structure With Openings

In order to address issues such as low wall bearing capacity,weak connection,and poor structural integrity that exist when promoting the application of cold-formed steel structures to multi-story systems,this research group introduced the concept of traditional masonry structures with ring beams and constructional columns into the multi-story cold-formed steel structure system,forming a new composite structure system of "ring beams + frame columns + cold-formed steel walls".This paper primarily investigates the seismic behavior of perforated walls in cold-formed steel frame-wall composite structures from both experimental and numerical perspectives.A calculation model for the lateral stiffness and load-bearing capacity of such walls under horizontal loads is established,and corresponding calculation formulas are proposed.Firstly,the failure modes and seismic behavior of five 1:1 scale perforated walls in cold-formed steel frame-wall composite structures under combined horizontal and vertical loads were studied.The experimental results showed that the failure mode of the composite walls was shear failure of self-tapping screws between diagonal braces and columns,and between steel skin and the skeleton of cold-formed steel walls.The greater the opening rate of the composite wall,the lower the lateral stiffness and shear bearing capacity.The stiffness degradation and strength degradation rates of each specimen were uniform,and there was no sudden change in stiffness or load-bearing capacity.The energy dissipation coefficient E of each specimen ranged from 0.564 to 1.705,indicating that each composite wall had good energy dissipation capacity.Secondly,a numerical analysis model of perforated walls in cold-formed steel frame-wall composite structures was established using ABAQUS finite element analysis software,and the correctness of the modeling analysis was verified using experimental research results.Based on this,the main parameters affecting the shear behavior of perforated walls were analyzed.The results showed that changing the strength grade of the frame columns could increase the shear bearing capacity of the wall to some extent,but did not significantly improve the lateral stiffness of the wall.The shear bearing capacity and lateral stiffness of the perforated wall increased with the increase of the wall skeleton thickness.Increasing the wall thickness of the cold-formed square steel tube frame column could improve the shear behavior of the perforated wall to some extent.With the decrease of the height-to-width ratio,the lateral stiffness and shear bearing capacity of the perforated wall were greatly improved.The shear bearing capacity and lateral stiffness of the perforated wall increased as the opening rate decreased.Finally,based on experimental research and finite element analysis,an analytical model for the lateral stiffness and shear-bearing capacity of cold-formed steel frame composite structure perforated walls was proposed.The formulas for calculating the lateral stiffness and shear-bearing capacity of perforated walls were derived and their correctness was verified.The results showed that the lateral stiffness and shear-bearing capacity formulas proposed in this paper based on the superposition method are in good agreement with the experimental and finite element results,with errors of about 10%,which can provide a reference for the calculation of similar wall lateral stiffness and shear-bearing capacity in the future.