Experimental analysis of the flexural behaviour of precast concrete composite beams with discontinuous connections

Abstract

Full-depth precast deck panels hold the potential to enhance constructability and productivity, and reduce the costs associated with highway bridges. This paper investigates the influence of discontinuous shear connections between girders and panels on the flexural behaviour of composite beams. Experimental findings from precast composite beams and direct shear tests are presented, including L-shape push-off tests and double shear tests to determine resistance at rough concrete-to-concrete plain interfaces and shear pocket connections. Composite beams with a full-depth precast slab connected through a shear pocket with shear keys into the upper face of a precast beam exhibit equivalent flexural resistance to monolithic beams when shear pocket spacing remains below the effective depth of the composite beam. However, composite beams with shear pockets featuring plain interfaces show a reduction in flexural resistance of up to 30% compared to monolithic beams. Moreover, composite beams with shear keys demonstrate interface shear stiffness up to four times greater than those with plain interfaces, indicating full interaction. The paper proposes simplified equations to estimate flexural resistance for composite beams with full-depth precast slabs joined by shear pockets, showing a coefficient of variation of only 12% compared to experimental results, offering a reliable method for predicting flexural resistance in composite beams with discontinuous connections.