Abstract Manager

Located in a highly urbanized area, the Saint-Martin boulevard is a strategic east-west traffic axis for the City of Laval. Two thick slab reinforced concrete structures allow users to make a U-turn or change direction on the boulevard near the CP railroad tracks. Built in 1970, each structure has two continuous spans of identical length (19.9 m) for a total length of 39.8 m and an overall width of 11.45 m. The bridges feature two traffic lanes and a 1.5 m sidewalk. The foundations consist of reinforced concrete abutments and a concrete central pier. Inspections carried out in 2019 showed the presence of small shear cracks on the outer sides of the slabs on both structures. A monitoring program of the concrete was established in 2019 and 2020. This type of structural issue is critical on thick slab bridges without shear reinforcement, as in this case. In 2021, a report following the evaluation of the structural bearing capacity of these two bridges recommended that a shear reinforcement needed to be installed on both bridges. Since the shear cracks are located in a thick slab, a durable solution had to be designed to increase the deck's shear strength, while maintaining the bridge's appearance and respecting the different site constraints. Due to the fact the bridges span over both the Saint-Martin boulevard and the bicycle path that runs alongside it, the vertical clearance to be maintained during the works was the reason for choosing to work from above the deck.

In this context, a glass-fiber reinforced polymer (GFRP) rebar reinforcement solution was developed to meet the reinforcement objectives. The advantage of this material is that it is not susceptible to corrosion, has high mechanical strength and is very light. Even compared with stainless steel, FRP bars are immune to chloride ion attack, and are compatible with the anchoring resins generally used. Its mechanical properties also demonstrate high tensile strength. What's more, design with this type of reinforcement is now covered by Chapter 16.5 of the S6-19 Code.