The effects of different steel sections on the performance of encased composite columns under cyclic lateral loads

The goal of this paper is to present the behavior and performance of a fully encased composite column subjected to horizontal cyclic load using the Finite Element Simulation. A parametric study was conducted using the numerical model to investigate the influences of geometric properties of fully encased composite (FEC) columns. The geometric variables were the shape of structural steel, column slenderness ratio (L/D) / the ratio of the length of the column (L), to the depth of the column cross-section, (D), and ties spacing ratio (s/D)/the ratio of transverse tie spacing, (s), to the depth of the column cross-section, (D). The nonlinear combined hardening and the concrete damage plasticity (CDP) model were used to define the properties of steel and concrete respectively.The finite element analysis results demonstrate that the profile of encased sections affects the performance of fully encased composite columns. Encased Tube Section (ETS) columns had good performance than Encased Circular Section (ECS) and Encased H- Section (EHS) due to their high stiffness. Increasing the slenderness ratio of the column from 7.5 to 11.25 and 15 reduces the lateral resisting capacity by 6.74 % and 15.83 % respectively. The tie Spacing also has significant effects on the lateral resistance capacity of the composite column. The effect is more observed in the buckling effects: as the spacing of lateral tie increases longitudinal reinforcement fails in bucking failure followed by crushing of concrete material before they reach their yielding stress.