An experimental, numerical and analytical study of hybrid RC-encased steel joist beams subjected to shear

The use of Reinforced Concrete encased Steel Joist (RC-SJ) beams, consisting of a steel joist partially or totally embedded in the concrete, represents in some cases an effective alternative to more traditional structural systems. While a lot of effort has been devoted to understanding flexural behaviour of such structures, up to now shear strength is an open issue. In this work, an experimental and numerical study on shear response of RC-SJ beams based on a preliminary test campaign is presented. Nine specimens were tested until collapse, which occurred due to shear failure. Numerical models obtained through the use of ABAQUS code were created, and different steel–concrete interfaces were used for the bottom steel plate. Based on the main outcomes of the experimental and numerical study, a novel analytical model is presented, and it allows for the estimation of shear strength in such structural elements. Application of the model to the beams tested shows a good agreement with real collapse values when a minimum bond between base and concrete is provided. A parametric study has been carried out, and it has allowed for the analytical model to be validated.