Effects of elastomeric bearing pads on the behavior of multi-span concrete beams with bonded link-slabs

Abstract

Jointless decks in multi-span bridge construction provide a cost effective solution by eliminating expansion joints. The construction procedure consists of providing simply supported spans using precast beam elements connected by a continuous reinforced concrete deck slab on top. The portion of the deck slab over the open joint at the intermediate supports is labelled as the link-slab. Current design procedures consist of debonding the link-slab from the precast beams near the intermediate supports to reduce its stiffness [1]. Nevertheless, bridge contractors prefer to keep the link-slab bonded to the precast beams as from a structural point they feel that the induced design forces in the bonded link-slabs are overestimated especially for bridges with elastomeric bearing supports [2]. This project examines the structural behavior of bonded link-slabs in multi-span bridges for various support conditions. It shows that elastomeric bearing pads reduce the link-slab induced forces. The project involves a comprehensive theoretical and experimental study where three reinforced concrete beams were tested under a static concentrated load using different support conditions. Data recorded was used to validate results from a numerical solution that was derived using Mathematica computer program [3]. The study confirms that the stiffness of the elastomeric bearing pads highly reduces the induced shear forces in the link-slab. A parametric study was then conducted for standard AASHTO type girders applications in the medium span length range to show the effects of the elastomeric bearings on the bonded link-slab structural behavior. Recommendations for designing bonded linkslabs were finally made and illustrated by a comprehensive numerical example.