Experimental and analytical investigations of concrete bridge decks with structural FRP Stay-in-Place forms
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Stay-In-Place (SIP) formwork systems are widely used for concrete slabs in industry due to their relative ease and speed of construction. Conventionally, corrugated metal sheets or precast panels are used as formwork. In recent years, the SIP formwork technique has been proposed in conjunction with Fiber Reinforced Polymer (FRP) composites. The resulting system combines the construction advantages of SIP formwork with the durability and corrosion resistance of FRP materials. Bridge decks are a particularly enticing application due to their exposure to harsh environmental conditions and the need for rapid construction to minimize traffic disruptions. This study broadly evaluates FRP SIP formwork for concrete bridge decks both experimentally and numerically. In total, 9 full scale bridge deck sections, 32 small scale decks and more than 40 auxiliary tests were conducted, including the construction and testing of a full bridge at scale. Additionally, a numerical model was developed to predict punching shear failure based on the theory of plates and shells. Experimental testing was conducted on two FRP SIP form configurations, namely flat plates with T-shape stiffeners and corrugated plates, and used a variety of different detailing and geometries. Some of the investigated parameters included the width effect of bridge deck section tests, the effect of deck span, the effect of bond at the FRP-concrete interface, the panel-to-panel splice configuration, concrete strength, and boundary condition at support, including a monolithic connection with precise girders. Results of the study include the determination of a critical aspect ratio for bridge deck sections, optimization of the panel-to-panel splice detail, and an assessment of the in-plane restraint available to interior span bridge decks. The numerical model, based on the Levy solution for loaded plates, produces a flexural response for a variety of bridge deck configurations and geometries. A failure criterion was applied to establish the punching shear capacity. The model was evaluated against experimental results and provided good correlation. It was then used to investigate a variety of FRP plate thicknesses, spans and effective widths for full scale FRP SIP formwork bridge decks.