Behaviour of composite beams with beam-to-girder end-plate connection under hogging moments

In this study, a new type of beam-to-girder end-plate connection used in steel-concrete composite beams was proposed to satisfy the requirements for accelerated structural construction. Five composite beam specimens using hinge joints, rigid joints, and end-plate joints at beam-to-girder joints were subjected to hogging moments. The failure modes, elastic stiffness, moment capacity, and cracking resistance of all specimens were monitored. The experimental results indicated that the end-plate connection significantly improved the mechanical behaviour of regular composite beams under hogging moments, resulting in good cracking resistance of concrete slabs. The cracking load, elastic stiffness, and moment capacity of the composite beam with end-plate joints increased by 30.8%, 54.9%, and 34.8% respectively compared with the composite beam with traditional hinge joints. Although the composite beam with rigid joints exhibited the best mechanical behaviour, its construction was costly and time-consuming. Increasing the reinforcement ratio effectively suppressed the development of crack width of concrete slabs, and changed the failure mode of composite beams. For composite beams with end-plate joints, the cracking load, elastic stiffness, and moment capacity of the specimen with a high reinforcement ratio were 19.0%, 41.8%, and 27.7% greater than those of the specimen with a low reinforcement ratio, respectively. Moreover, based on the Navier-Bernoulli assumption, a method for calculating the elastic moment capacity of composite beams with end-plate connection under hogging moments was proposed and its applicability was verified by comparisons between experimental and analytical results.