Behavior and Design of Link Slabs for Jointless Bridge Decks

Abstract

Maintenance of bridge deck joints is a costly problem. Debris accumulation in the joints can restrain deck expansion, caus ing undesirable forces in the deck and damage to the structure. Water leaking through the joints is a major cause for the deterioration of bridge girder bearings and supporting structures. Therefore, elimination of deck joints at the supports of multispan bridges will reduce the cost of construction and maintenance. This paper presents the results of a test program to investigate the behavior of link slabs connecting two adjacent simple-span girders, and proposes a simple method for designing the link slab. To illustrate the proposed design method, three design examples are included.

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“…Adoption of the jointless bridge design concept eliminates the expansion joint at the bridge center, thereby minimizing future maintenance efforts associated with cracked decks. The design of the ECC link slab follows the link slab design guidelines offered by Caner and Zia [1] originally proposed for concrete link slabs. The link slab is designed to be sufficiently flexible (offering no rotational restraint) to permit the spans on both sides of the link slab to behave as simply supported elements.…”

“…The link slab is designed to undergo strain induced by the moments developed at the span-link slab interface. If the link slab moment of inertia, I ls , and elastic modulus, E, are known, then the constant moment, M ls , developed in the link slab due to the relative rotation, θ, at the link slab ends is given [1]:…”

“…The Caner and Zia [1] link slab design procedure directly correlates top surface strain in the link slab element to the rotation induced at the link slab ends (Equation 1). To experimentally validate this relationship for an ECC link slab, the Figure 6.…”

“…The result is a link slab that renders the bridge deck continuous but also permits the spans to operate independently as would be the case with expansion joints. Since the initial study by Caner and Zia [1], a number of bridges in the United States have adopted the jointless bridge design concept. For example, Wing and Kowalsky [7] report on a long-term monitoring study that measured the performance of a jointless bridge designed in North Carolina; the link slab in their study employed concrete as the primary slab material.…”

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“…The leaking expansion joints are a major source of deterioration of multi-span bridges in Canada. Expansion joints can be replaced by flexible link slabs made with ECC forming a joint-free multi-span bridge and hence, solving the problem of premature deterioration [23,24]. Research studies showed significant enhancement of ductility and crack width control in ECC link slabs confirming that the use of ECC can be effective in extending the service life of bridge deck systems.…”