Ductility Evaluation of Steel Bridge Piers with Pipe Sections

Abstract

The present paper is concerned with ductility evaluation of steel pipe-section bridge piers under cyclic loading. For this purpose, an elastoplastic large deformation analysis is carried out to obtain cyclic behavior of the columns. In the analysis, a modified two-surface plasticity model developed at Nagoya University is employed to account for material nonlinearity. The developed finite-element formulation takes into account such important cyclic characteristics of structural steel as the decrease and disappearance of the yield plateau, reduction of the elastic range, and cyclic strain hardening as well as the spread of plasticity across the section. Comparisons between the analytical and experimental results show that the modified two-surface model gives closer prediction of the inelastic cyclic behavior of steel structures than isotropic and kinematic models. A parametric study is then conducted to investigate the effects of radius-thickness ratio, slenderness ratio, magnitude of axial load, and number of loading cycles on the strength and ductility of the columns. Finally, empirical formulas of the strength and ductility are proposed for steel bridge piers with pipe sections.