Small Deflection Buckling Analysis Of Built-up Web For Cold-formed Steel Short Column In Axial Compression

For the small deflection theory of single board,a relatively perfect theoretical system has been established.However,for the cold-formed steel(CFS)screw connected built-up plate,due to the discontinuity of the plate and the existence of self-drilling screws lead to the force performance of the connected plate and the force performance of the single plate is different,so the theory of single plate can not be directly applied to the built-up plate.In view of this,this paper will use theoretical analysis,experimental research and finite element simulation to explore the refractive mode of CFS screw connected plate and the factors affecting the critical stress of screw flattening plate,and finally the precise calculation formula for solving the critical stress is obtained through regression analysis.The following work has been mainly done:(1)Based on the small deflection theory of the single plate and the existing research theory,the theoretical formula is pushed to the four-sided simple CFS screw connected built-up plate,and the formula for calculating the critical stress of the screw flattening plate is obtained.(2)The CFS double-limbed C-shaped basic members were assembled with screws to create four-sided simple-supported screw assembly panels for experimental research.The experimental study mainly analyzed the elastic buckling pattern of the screw flattening plate and determines the critical stress value.(3)The ABAQUS finite element software was used to simulate each test specimen.The comparison between the simulation results and the finite element results verified the accuracy of the finite element model.On this basis,length-width ratio,width-thickness ratio,screw diameter and screw spacing were analyzed,and the deformation mode of screw flattening plate and the change law of critical stress of screw flattening plate were obtained.(4)The results obtained by finite elements were compared with the theoretical formula,and the correction coefficient k_c was introduced with the finite element results.Finally,the coefficient was fitted to obtain the precise solution of the formula of the small deflection theory of the screw connected built-up plate.