Stability Bearing Capacity Of Thin-walled Cold-formed Steel Columns With Complicated Crimping And Unequal Angle Cross-section Under Eccentric Compression

With the development of urbanization,assemble-type of light-steel modular house(ATLS modular house)is widely used in practice due to its convenient transportation,reusability and quick disassembly and assembly.The requirements for its use in engineering are also increasing,it is mainly reflected in its cold-formed thinwalled steel components.Currently,most of the research on cold-formed thin-walled steel members focuses on C-shaped and Z-shaped steels and shaped steel members with symmetrical cross-sections,The cold-formed thin-walled steel members with unequal angular cross-sections with complex curling edges lack corresponding design guidance in China's "Technical code of cold-formed thin-wall steel structures",and scholars at home and abroad have little research on the column with non-symmetry axis section.In addition,In practice,there are very few components that are completely axially compressed.Therefore,this article uses a combination of experimental and theoretical research,and use simulation software,Study its stability under eccentric compression,ultimate bearing capacity and design formula based on direct strength method.Mainly complete the following work:(1)Experimental study on cold-formed thin-walled steel columns with unequal angular cross-sections with complex curling.The test part mainly includes actual size measurement of test piece,material test of test piece,initial defect measurement of test piece,eccentric compression test of 8 500 mm steel columns and eccentric compression test of 8 1500 mm steel columns.Through the above test,distribution of initial defects in test pieces,deformation of specimen under different eccentric pressure,bearing capacity,deformation distribution of the section at the central height of the specimen,load-axial displacement relationship curve are studied.(2)Numerical simulation study and analysis of the stability and ultimate bearing capacity of cold-formed thin-walled complex curled unequal angle section steel members.First,finite element simulation was carried out on the 16 test pieces in the test,verified by analysis,confirm that the finite element model can well predict the bearing capacity and instability mode of cold-formed thin-walled members,then use the finite element model for parametric analysis.By changing the eccentric direction,eccentricity,thickness and length of the component,120 models were built,to study the effect of different parameters on the bearing capacity and deformation mode of the component.(3)Theoretical formula fitting.Using the parametric analysis data in this paper,based on the existing direct strength method,the eccentric compression members are fitted with formulas to obtain the calculation of the bearing capacity of cold-formed thin-walled complex curling unequal angle cross-section steel members under different direction bias Formula,and verify the validity of the formula through the test data.Finally,the calculation formula of the bearing capacity of four biased members under different conditions is finally obtained,the results are relatively conservative,design biased towards safety.