Eliminating Deck Joints Using Debonded Link Slabs: Research and Field Tests in Ontario

One of the main factors affecting the durability of bridge structures is the presence of expansion joints at bridge support locations. The inability of current joint systems to provide reliable, long-term, leak-proof performance generally leads to early leakage of chloride-contaminated water through these joints, thereby causing premature corrosion in the deck elements below. This problem is particularly evident in older-type multispan bridges in which the girders are simply supported at the piers and are separated by expansion joints or simple paved-over joints. To address this problem, the Ministry of Transportation of Ontario (MTO) has recently rehabilitated a number of bridge decks using a debonded link slab system to replace the deck joints at the pier locations. To get a better understanding of the performance and reliability of this new rehabilitative technique, MTO recently carried out an experimental research study of the long-term performance of the system on scale test models that were subjected to extensive cyclic loading in the laboratory. At the same time, it carried out a load test of a recently rehabilitated structure to study its structural behavior both before and after the link slab was constructed. The test structure was instrumented with sensors that measured deflections and strains in the link slab and girders. This paper describes the experimental research study and the behavioral load tests that were carried out, and discusses the results obtained. The experimental study showed that the long-term performance of the link slab was not affected by the extensive cyclic loading to which the model was subjected, whereas the load testing of the test structure showed that it satisfied the serviceability limit state requirements of the Canadian Highway Bridge Design Code, thus validating the design methodology of the system.