Analysis And Design Of Triangular Cold-Formed Thin-Walled Steel Roof Truss Mechanical Properties

Based on the finite element numerical analysis method for three different single cross slope to the triangle Howe mechanical mechanism of the cold-formed thin-walled steel roof truss was studied,the failure mode of the triangle truss is local buckling failure rather than overall buckling failure of roof,and the damage location for roof top chord and bottom chord bending at the junction of upper chord and bottom chord of local buckling failure;Compared with the lower chord,the deformation of the upper chord is more obvious.Firstly,two trusses of triangular cold-bent thin-walled steel roof trusses with roof of Nuthaporn Nuttayasakul were tested and verified.In the condition of single cross triangle Howe cold-formed thin-walled steel roof truss roof span to height ratio,span and chord and the thickness of CHS,horizontal load,chord and the ventral pole size,roof truss type and chord section form influence the roof truss vertical bearing capacity,yield load and the factors on the change of elastic stiffness parameter analysis,by analyzing the available: triangle Howe limited bearing capacity of cold-formed thin-wall steel roof truss and yield increase with the increase of the load with the roof span ratio,the elastic stiffness showed a trend of decrease after the first increase;As the span of triangular roof truss increases,the ultimate load,yield load and elastic stiffness of triangular roof truss decrease gradually.With the increase of the thickness of triangular roof truss,the ultimate bearing capacity,yield load and elastic stiffness increase gradually,and the chord has a more obvious increase than the web.As the size of triangular roof truss increases,the ultimate bearing capacity and elastic stiffness increase gradually,and the yield load first increases and then decreases.Compared with common u-shaped chord,hat shaped chord and complex hat shaped chord,the ultimate bearing capacity,yield load and elastic stiffness of triangular roof truss increase successively.The existence of horizontal load will reduce the ultimate bearing capacity and elastic stiffness of triangular roof truss.Yield load decreases first and then increases.Horizontal load is an important factor affecting the limit state of triangular roof truss.Fink roof truss has higher ultimate bearing capacity and yield load for triangular roof truss with smaller span to height ratio.Double Fink roof truss is selected for large triangular roof truss with large span height,which has higher ultimate bearing capacity and elasticstiffness under yield load.Secondly,the stability analysis of the triangular cold-formed thin-walled steel roof trusses is carried out.According to the concept of structural stability analysis,the linear elastic stability and nonlinear stability of the triangular cold-formed thin-walled steel roof trusses are analyzed,and the calculation method of the stability of triangular cold-formed thin-walled steel roof trusses is determined.Finally,the applicability of existing specifications is verified by the test design of triangular howie cold-formed thin-walled steel roof truss.