Abstract:
In national technical specification with specially shaped columns (JGJ149-2006), the relationship between axial compression ratio and stirrup characteristic value in various seismic grades were derived according to various ductility level, which came from ductility analysis of 12960 equiaxial specially shaped columns and some inequiaxial L-shaped columns. Based on the same constitutive model and the ultimate curvature criteria, the ductility of 1456 inequiaxial T-shaped and cross-shaped columns are analyzed by nonlinear method, and the curves between axial compression ratio and stirrup characteristic value in various ductility level are derived. Comparing with equiaxial columns in the same ductility ratio, some conclusions are derived: 1) the inequiaxial T-shaped column curves between axial compression ratio and stirrup characteristic value are similar to the equiaxial columns; 2) the inequiaxial cross-shaped column curves between axial compression ratio and stirrup characteristic value are similar to the equiaxial columns when the ratios of the flange length are less than 1.4, but the axial compression ratio may reduce 0.07―0.08 when the ratios are great. It is suggested to add concealed columns or shortening stirrup space in the same stirrup reinforcement ratio to increase axial compression ratio in the latter.