Concrete confinement and degree of shear connection effects in hybrid column design

Abstract

This paper presents a numerical study on concrete confinement and degree of shear connection effects on the ultimate load of hybrid steel-concrete columns with several encased steel profiles. Primarily, a co-rotational finite element for large displacement analyses of hybrid beam-columns in partial interaction and with shear deformability of concrete component is developed. In local co-rotational coordinate system, a fiber model considering the triaxial stress state in the concrete component is adopted. This consideration enables to take into account the contribution of the transverse reinforcement on concrete confinement by using the extended plane stress algorithm, in which the transversal equilibrium between the concrete fiber and the transverse reinforcing bar is imposed. The performance of the FE model is illustrated by comparing its results against experimental three-point flexural bending tests of hybrid beams. The results of parametric study using the FE model show that for low to high column slenderness, the ultimate load of hybrid column increases significantly with respect to the transverse reinforcement ratio. Besides, the ultimate load of slender columns in full interaction can be obtained for columns with a relatively high shear connection stiffness at the extremities without shear connection along the column height.