Buckling Behavior And Design Method Of Cold-formed Thin-walled Steel Members With Web Openings Under Axial Compression

The cold-formed thin-walled steel structure has been widely used in water conservancy scenic spots due to its many advantages in recent years.Such cold-formed thin-walled steel members often need to open holes in the web in order to facilitate auxiliary equipment,piping and support.However,there is no specific formula for calculating the buckling strength of cold-formed thin-walled steel members with holes in the current code in China.It is significance to further perfect the design specification of cold-formed steel section with open hole.This paper puts forward the design theory and calculation method which is consistent with the current cold-formed thin-walled steel code in China by using the finite element analysis,and verify the results by using numerical simulation,and relevant test data at home and abroad were collected for comparative analysis to improve the reliability of the results.Firstly,the design specifications of cold-formed thin-walled steel structures at China and abroad are collected.The main methods for calculating the elastic local buckling,distortion and overall buckling of the cold-formed thin-walled members with open holes under the axial compression are summarized,including opening restrictions which provides accurate theoretical basis for follow-up research.Then the elastic buckling performance of the perforated plate under the axial compression is analyzed by ABAQUS finite element software in this paper,including the influence of the perforated plate size and width-thickness ratio shape,the size and position and distance of the holes is also discussed.The results show that the opening position and size have a greater influence,based on the parameter analysis,the more accurate restriction conditions of opening are proposed,the proposed formula of buckling stability coefficient k for the axial compression perforated plate is given.Then the influence of the parameters such as opening type,opening size and position of the cold-formed thin-walled lipped channel steel members with web openings under axial compression are analyzed,which with the distortional buckling and the overall buckling performance.The results show that the opening of the holes will not only weaken the bearing capacity of the web,but also changed the constraint effect between the connecting plates.The buckling stability coefficient k of the member has a different degree of reduction when the web opens with a single circular hole or a multi circular hole.Finally,according to the obtained analysis parameters,a relative reduction formula is proposed for different types of openings of cold-formed thin-walled lipped channel steel members with web openings.Finally,the experimental data,finite element analysis results,the proposed formula results and the calculation results by code of American were compared and analyzed,the results show that the calculation results by proposed method are closer with the experimental values,and the coefficient of variation is smaller relatively,due to the influence of the local buckling,distortional buckling and the overall buckling by the openings are considered,the calculation result of the formula is close to the result of finite element analysis.The proposed method has practical reference value.