Behavior of Ultrahigh-Performance Concrete Bridge Decks with New Y-Shape FRP Stay-in-Place Formworks

Abstract

This study proposes using glass fiber-reinforced polymer (GFRP) as a stay-in-place structural formwork for casting bridge decks with ultrahigh-performance concrete (UHPC). The GFRP stay-in-place formworks completely replace the bottom layer of rebars, and the top steel reinforcement is also replaced by a GFRP mesh to mitigate the corrosion damage. The formworks were either a flat GFRP plate with square hollow section (SHS) stiffeners or a flat GFRP plate with new Y-shape stiffeners. Concentric static tests on five 1:2.75 scale decks were performed to investigate the effect of stiffener's configuration and the influence of the concrete strength on the performance of bridge decks. Rotational fixity support was used to simulate a real bridge deck connection of supporting girders. All specimens with the stay-in-place formwork exhibited punching shear failure. It was found that the use of Y-shape stiffeners significantly improved the load-carrying capacity of the proposed deck. Replacing normal concrete with UHPC further improved the loading capacity of the deck. The decks demonstrated excellent performance, with the load-carrying capacity 3.8-9.5 times higher than the established equivalent service load depending on the concrete strength and configuration of the GFRP stay-in-place formwork. Deflection at service load was less than span/1,600 for all the decks. Compared with normal-strength concrete (34 MPa), UHPC improved the maximum load-carrying capacity of the deck from 91.4 to 149 kN.