Evaluation of the flexural behavior of composite beam with inverted-T steel girder and steel fiber reinforced ultra high performance concrete slab

• A composite beam combining a UHPC slab and a steel girder without top flange was proposed.
• The steel girder is an inverted-T beam and requires to dispose the studs on the web.
• The material model considers the empirical tension-softening behavior of UHPC.
• The proposed analysis method considers the strain compatibility conditions of the beam member.
• Good accuracy of the predictions is achieved by the proposed analysis model.

Huge efforts have been made to develop ultra high performance concrete (UHPC) and exploit its remarkable properties. Among the achievements, various solutions were proposed to achieve optimal composite beams using steel fiber reinforced UHPC. In order to increase the economy in material, a composite beam combining a slab made of UHPC and a steel girder without top flange is proposed. In this composite beam, the inverted-T steel girder requires the studs be arranged on the web for the composition with the UHPC slab. Considering the absence of studies evaluating the flexural behavior of this new type of composite beam, this study examines experimentally the flexural behavior with respect to the stud spacing and slab thickness. To that goal, eight composite beams with varying stud spacing and UHPC slab thickness were fabricated together with two additional composite beams using slabs made of normal concrete without steel fiber reinforcement for comparison. In addition, an analysis method considering the tension-softening behavior of steel fiber reinforced UHPC in the material model and the corresponding strain compatibility conditions of the beam member is proposed. The comparison of the analytic and experimental results reveals the good accuracy of the predictions indicating that the empirical tension-softening curve reflects reasonably the actual behavior of steel reinforced UHPC composite member.