The behaviour and design of haunches in composite beams and their reinforcement

![CDATA[Haunches can be formed as part of a solid slab to increase composite beam depth or they can occur directly in primary composite beams incorporating open rib trapezoidal steel decks with the concrete ribs, often narrow, laid parallel to the longitudinal axis of the steel beam. In solid slabs, haunches can be designed to provide full shear connector strength. In composite slabs, the geometry of the concrete ribs is limited by the deck geometry. This can result in a reduction in stud connector strength below that for a solid slab and is taken into account in design codes by the use of stud strength reduction factors. Brittle failure modes have been observed in recent testing on specimens incorporating trapezoidal steel decks. The reductions in stud strength were significant and could be more severe than those predicted by design codes. Two types of reinforcing components have been developed to control the brittle failure modes and to provide increased stud strengths and improved stud ductility.]]