Limit analysis of reinforced concrete slabs with construction joints

摘要

Reinforced concrete slabs constructed of precast elements and in situ concrete are commonly used for short-span road bridges. The construction joints between the concrete cast at different stages reduce the torsional capacity and thus the load-carrying capacity of the slab. However, the present formulations for the torsional capacity, based on limit analysis, only consider monolithically cast slabs. In this paper, the load-carrying capacity of reinforced concrete slab bridges with construction joints are investigated using limit analysis of perfect plastic materials based on the lower bound theorem. New formulations for the torsional capacity of slabs with vertical construction joints and partial construction joints are presented. The load-carrying capacity of slabs is calculated using finite element limit analysis based on the lower bound theorem. For the analysis, a complete yield criteria for the bending moments and torsional moments are setup applying a layer model. The size of the layers is calculated from the moment capacities and the derived torsional capacities. Examples of limit analysis of slabs with and without construction joints are compared, which demonstrate the reduction due to the construction joints.