Simplified Dual Nonlinear Analysis Method of CFST Laced Structures

Abstract

Based on continuous assumption, laced CFST member can be simplified as a beam element. Stiffness of Timoshenko beam was adopted to calculate the equivalent solid member stiffness matrix of the laced structure, in which the ratio of shear rigidity to bending rigidity was taken into account. Efficient rigidity was used in the element stiffness matrix to consider initial deformation influence on ultimate stability bearing capacity. A program of finite element method in FORTRAN language was presented. Calculation examples show that calculation results by the presented simplified method agree well with those of general FEM with beam and bar elements. It can be used to analyze CFST laced structure with less element numbers, and can simplify the calculation and save computer time. The influence of correlation buckling and shearing deformation on ultimate bearing capacity was discussed. The results show that (1) the influence of shearing deformation decreases with increasing of the slenderness ratio; (2) the influence of shearing deformation increases with increasing of the area ratio of chord member and web member; (3) local buckling of chord member occurs for CFST laced column with