Analysis of bonded link-slabs in precast, prestressed girder bridges

Abstract

Link slabs provide continuity in the deck slab over the intermediate supports of multiple-span bridges where precast, prestressed concrete girders are used. Current practice recommends debonding the link slab from the girders ends to reduce its stiffness. Steel reinforcement is consequently provided to satisfy the dead- and live-load criteria. A survey of bridges in the United States indicated that full-depth cracks still develop in the link slab and some practices are placing the link slab without debonding. Although design procedures for debonded link slabs are currently available, data related to bonded link slabs is scarce. This paper investigates the structural behavior of bonded link slabs due to dead and live loads. It examines the contribution of the stiffness of the link slab on redistribution of shear and moments. Closed-form solutions were derived for a three-span symmetrical case and a parametric study conducted based on standard American Association of State Highway and Transportation girders commonly used in the medium-span-length range. It was shown that the link slab parameters, if optimized, can strengthen the connection in the continuity zone to resist the induced loads without affecting its resisting capacity.