DIRECT STRENGTH METHOD STUDY ON ULTIMATE LOAD-CARRYING CAPACITY OF H-SHAPED CROSS SECTION WITH LARGE WIDTH-TO-THICKNESS RATIO UNDER AXIAL LOAD

The ultimate load-carrying capacity of columns under an axial load with a large width-to-thickness ratio and H-shaped cross sections was studied by a nonlinear finite element analysis using ANSYS program. The influence of the material plasticity and geometric imperfection was considered in the analysis. A total of 44 columns with different sizes, material yield strength and other parameters were analyzed. The ultimate load-carrying capacities of columns were also computed by using a direct strength method and a traditional effective section method. The results show that the average ratio of the results calculated by the finite element analysis to the direct strength method is 1.039; the average ratio of the results calculated by the finite element analysis to the effective section method is 1.098. Compared with the direct strength method, the effective section method tends to being tedious and lightly conservative. It indicates that it is feasible to calculate the ultimate load-carrying capacity of columns of H-shaped cross sections and large width-to-thickness ratios under axial loads by the direct strength method, originated from the ultimate load-carrying capacity calculation of cold-formed steel structure members with singly symmetric cross-sections.