Hybrid RC-steel members under bending and shear: Experimental investigation and design model

This paper presents an experimental campaign and a design method for concrete-steel hybrid walls with several embedded steel profiles. In the first part of the paper, an extensive experimental investigation on the static behavior of hybrid walls subjected to combined shear and bending is presented. Six full-scale hybrid walls with different types of the structural steel-concrete connection and reinforcement detailing were tested. The experimental results indicated that the load bearing capacity of the hybrid specimens considerably grows, as a result of the encased steel profiles. It was found that specimens with shear connectors (i.e. headed studs, stiffeners) are more ductile in terms of displacement ductility than the ones without connectors. Next, a design model for hybrid elements (walls and columns) subjected to combined axial force, bending and shear is proposed. This model is based principally on the design rules of Eurocode 2 and Eurocode 4. Particular attention is paid to longitudinal and transversal shear resistances. A strut-and-tie model is developed to evaluate the transverse shear resistance taking into account the contribution of the steel profiles. Furthermore, an analytical method is proposed for the prediction of the longitudinal shear stress at the concrete-steel profile interface which allows to design adequate shear connection between the steel profile and concrete. Finally, to assess the validity of the developed design model a comparison between the experimental results and design predictions is presented.