Modeling of Flexural Behavior and Punching Shear of Concrete Bridge Decks with FRP Stay-in-Place Forms Using the Theory of Plates

Abstract

A robust analytical model for predicting full response and ultimate load of concrete bridge decks constructed with fiber-reinforced polymer (FRP) stay-in-place (SIP) structural forms is presented. It adopts the plate theory to establish surface deflections, while incorporating concrete nonlinearity in compression and cracking in tension, as well as the degree of bond between the FRP SIP form and the concrete. The model accounts for various boundary conditions at the edges of the deck in both directions, including both finite and infinite width in the direction of traffic, and either fixed or hinged conditions in the other direction, depending on the connection to the support girders. A punching shear failure criterion was incorporated to predict the ultimate load. The model was validated against a large experimental database, and reasonable agreement was observed. The average percent difference in ultimate loads was 5.5%. The model was then used in a parametric study to assess the FRP reinforcement ratio in terms of the FRP plate thickness, the width of the deck parallel to traffic, and the span of the deck, which is the girder spacing. It was shown that reducing the FRP reinforcement ratio from 10.7 to 2.7% results in about a 20% reduction in punching shear ultimate load. The ultimate loads obtained for decks with (width/span) aspect ratios of 2.73, 1.33, 0.87, and 0.55 were 100, 94, 83, and 73%, respectively, of the ultimate load of the real condition of infinite width. Finally, the punching shear load decreased by about 18% as the deck span-to-depth ratio increased from 10 to 16.5.