Rolling Load Fatigue Experiment on a Bridge Deck Reinforced with a New Design of GFRP Stay-In-Place Form

Abstract

A full-scale deck slab (15,240 mm × 3,890 mm × 210 mm) supported by steel girders spaced at 3.05 m, including a 3,810 mm × 3,890 mm section incorporating a new design of glass fiber–reinforced polymer (GFRP) stay-in-place (SIP) structural form, is tested under 3M rolling load cycles. The SIP form comprises transverse GFRP I-beams spanning the steel girders and GFRP ribbed plates (planks) spanning the transverse GFRP I-beams and supported by their lower flanges. The design of the SIP form was governed by readily available pultruded sections such that they meet deflection limits under self-weight of fresh concrete and also provide reinforcement ratios comparable to, or exceeding, the Canadian Highway Bridge Design Code (CHBDC) requirements for GFRP rebar. This deck section is compared with another section designed according to CHBDC with top and bottom GFRP rebar meshes. The deck was tested using the 250 kN Rolling Load Simulator (ROLLS) at Queen’s University, Canada, which is equipped with two half-axles spaced at 1.2 m, each comprising nitrogen-inflated dual tires. After 3M cycles, the section with SIP structural form showed very similar performance to that of the GFRP rebar section with the stiffness reducing by 72% in both. Nearly 90% of stiffness reduction occurred in the first 0.4M cycles. The residual deflection of the SIP form section was only 60% of that of the rebar section at 3M cycles. Live load deflection ratio reached 3.4 at 3M cycles, almost identical to the rebar section. The span/800 deflection limit was reached at 0.8M cycles, compared with 1.1M cycles for the rebar section. The maximum tensile strain reached in the GFRP SIP form system after 3M cycles was only 11% of its ultimate value. The use of glass fiber–reinforced polymer material as reinforcement for bridge decks has been well investigated. Researchers have also investigated the applicability of a reinforcement design concept, stay-in-place (SIP) form, which acts as both formwork for casting concrete and permanent reinforcement. This paper investigates the rolling load fatigue performance of a full-scale GFRP SIP form reinforced bridge deck. The GFRP SIP form system featured in this study is made from an off-the-shelf product. The experiment simulated actual traffic load with air-inflated rubber tires for 3 million cycles and the bridge deck exhibited adequate performance.