Link Slab eliminate bridge joints

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The motivation for this article(Link Slab eliminate bridge joints) came from a question from one of  our users , so I decided to prepare some issues  about link slab.

Background

In order to accommodate lateral and rotational movement between adjacent spans due to load and concrete  shrinkage temperature ,expansion joints are built into bridge deck.

The joints must be constructed such that the bridge deck is protected from corrosion due to water seepage Moreover, it has been reported that chloride- contaminated water leakage through the expansion joints often shortens the life of such joints, with serious durability implications for the deck

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The cost efficiency and ease of use of link slab components to eliminate expansion joints have generated increasing attention and have been extensively reported.but The AASHTO Standard specifications do not provide guidelines for the design and detailing of link slabs.

There are two types of link slabs: a full-depth link slab and a partial-depth link slab:

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Link slabs were detailed with a debonded zone equivalent to 5% (Debonded link slab configuration tested by Caner and Zia ) of each adjacent bridge span to reduce stiffness and stresses ,This debonding was achieved by removing any structural mechanism capable of transferring load (e.g., stirrups and shear stud connectors) and by placing a bond breaker material between the beam and the deck.

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The approach to creating link slabs provides for the redistribution of forces caused by the removal of joints that previously allowed for both translation and rotation,Several materials have been used in construction of link slabs ,but today most of the investigations , in order to minimize cracking and traffic destruction , promote the use of advanced concrete materials with link slabs such as LMC (Latex Modified Concrete),ECC (Engineering Cementitious Composite), UHPC(Ultra High Performance Concrete) and so on.

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Previous investigations declared  that factors that directly affect the response of bridges with link slabs are: support conditions, debonded length, temperature gradients, concrete type, girder type, reinforcement ratio, interfacial bond strength, link-slab thickness, span-length ratio,  girder height, and skew

Some State departments of transportation(DOTs) in the United States have  large numbers of link slabs installed and  have design details and sample of calculations and recent research or innovative installation techniques are featured  such as North Carolina ,Virginia ,New York  , Massachusetts, Florida and Utah.

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References

1.FEDERAL HIGHWAY ADMINISTRATION Office of Bridges and Structures FHWA-HIF-20-062 “Eliminating Bridge Joints with Link Slabs “– An Overview of State Practices November 2020

2.Caner, A. and Zia, P. (1998). Behavior and Design of Link Slabs for Jointless Bridge Decks. PCI Journal, 43(3):68–80

3.Lifei Zhang and et al  (2021)“Structural performance evaluation of ECC link slabs reinforced with FRP bars for jointless bridge decks” 0950-0618/© 2021 Elsevier

4.Ghadir Haikal and et al “Link Slab Details and Materials” Report Number: FHWA/IN/JTRP-2019/10 • DOI: 10.5703/1288284316920

5.Kelvin DeGrow “Use of Link Slabs in the Highway 17 Over Battle River Bridge Rehabilitation” of the 2020 Conference of the Transportation Association of Canada

6.Virginia Department of Transportation. (2018). Manual of the Structure and Bridge Division, Part 2 Chapter 32, File No. 32.09-1, Richmond, VA,