LINK SLAB DECK JOINTS

There is increasing pressure on bridge designers to minimize joints on bridge decks in order to reduce maintenance and long-term rehabilitation costs. One method of achieving this that is gaining popularity in recent years is the use of concrete link slabs. A concrete link slab is a relatively thin reinforced concrete slab that typically connects simply supported deck spans. It is designed to flex due to girder deflections and also transmit compressive and tensile forces through the deck in conjunction with appropriately designed bearings. This paper will describe available design methodologies and provide an example of its application for a bridge retrofit. Link slabs are currently being installed in new bridge construction, and also used to replace expansion joints in the rehabilitation of existing structures. The applicable use of link slabs in the field is limited by variables such as girder end rotation from applied loads, bridge skew, and girder depth. Link slabs are designed to flex, however excessive deflection causes potential for the development of wide cracks, exposing the interior steel reinforcement to susceptibility of corrosion. The concrete deck is typically composite with the supporting steel or concrete girders, but is debonded in the link slab region to increase the link slab curvature length, resulting in a reduced slab flexure and minimizing cracking. Although flexural cracking cannot be completely eliminated, water ingress into the cracks can be controlled by the following design considerations: limiting deck crack opening width by limiting end girder rotation; application of waterproofing membrane on top of concrete deck; and use of fibrereinforced concrete in the link slab.