Design of Slender Composite Bridges Considering Available Support Region Rotation Capacity

The objective of this paper is to present a simple design method which is able to account for slender composite beam ductility when verifying a continuous bridge load carrying capacity. As ductility in the support region of slender composite beams is insufficient for plastic design, a design method is proposed which is able to account for the limited support region ductility and avoids the precise elastic verification of cross sections. In the first part of the paper, the composite beam local behaviour is investigated and the principles for calculating the cross section resistance and available rotation capacity are discussed. In the second part, the various possibilities of using the existing support region ductility are presented together with the corresponding required rotation capacities. Finally, the verifications needed to assure that the beam load carrying capacity is sufficient are presented.