Experimental and Theoretical Study of Composite Cold Formed Steel-Concrete Beams

This paper presents an experimental investigation and theoretical analysis using finite element model for composite cold formed steel beams. Experimental tests are carried on full scale composite cold formed steel (CFS) beams. The steel beams consist of two cold formed steel channel sections back to back which connected to a reinforced concrete slab using new means to transfer the shearing force between them to achieve the composite action. Two groups of beams have been tested. In the first group, the composite action has been achieved using the embedment of the upper part of steel section inside the concrete slab. In the second group, the composite action is achieved using the reforming of the steel flange inside the concrete slab to act as shear connectors. The parameters studied in the first group are the ultimate strength of the concrete, height of the embedded part of the steel section in the RC slab, effect of the interaction between shear and bending moment depending on the loading method, the direction of the applied load with respect to the beam position, and effect of encasing steel web with concrete. While the studied parameter in the second group, is the spacing between the new shear connectors developed from the reforming of the steel section flange. The beams? ultimate strengths, load-mid span vertical deflection relationships and failure modes of the beams have been recorded from the tests. The finite element analysis has been performed using ABAQUS. The ultimate strengths and failure modes from nonlinear analysis are compared with the experimental results to verify the accuracy of the developed models.