Concrete to steel lap joint failure criteria under combined shear and peeling stress

Bonded composite steel–concrete bridges are an interesting alternative to traditional composite bridges with metallic connections. However, one cannot limit the bonding joint design to longitudinal shearing, although that remains important. It is important to consider the out-of-plane tensile stress which develops along the bonded joint and is caused by the transversal bending of the beam, especially in the case of twin-beam structures, and also the differential bending between the metallic profile and the concrete slab under concentrated load, which can cause brittle failures.This article aims, firstly, to model the behaviour of the adhesive lap joint of concrete/steel composite beams connected by bonding. De-bonding is caused by shear and peeling stress, which is calculated under local loading. Secondly a bi-axial failure criterion (shearing–out-of-plane tensile stress) in the bonded joint is established through the use of an original experimental procedure. Finally, it seeks to validate this criterion on a simply supported bonded composite beam of 3.3 m, which is subjected to a static load until failure, using a theoretical-experimental approach. The first results obtained are very encouraging and show that the established quadratic interaction criterion is well-adapted.