Ductility Issues in Thin-Walled Steel Structures

Abstract

This chapter investigates the ductility of thin-walled steel stub-columns with and without longitudinal stiffeners through extensive parametric analyses. The key parameters affecting the ductility of box stub-columns are found to be the flange width-thickness ratio, magnitude of the axial force, and the stiffener's slenderness ratio. A simply supported boundary condition is assumed along the column end-plate boundaries to simulate the local buckling mode of a long column, which would deform into several waves along the length. To impose a rotation of the edge, the end sections are constrained as rigid planes by using the multipoint constraint boundary conditions and the rotation displacement is applied at any node on the sections. The bending moment is obtained as the reaction force of the node. The general FEM program ABAQUS and a type of four-node doubly curved shell element included in its package are employed in the elasto-plastic large deformation analysis. An idealized rectangular form of residual stress distribution in each unstiffened panel, stiffened panel, and stiffener plate is adopted due to the welding. For unstiffened stub-columns, the shape is assumed to be sinusoidal in both flange and web plates.