Design Equations for Concrete Bridge Decks with FRP Stay-in-Place Structural Forms

Abstract

Bridge deck construction using stay-in-place (SIP) fiber-reinforced polymer (FRP) structural forms has shown promise as an efficient, rapid, and low-waste alternative to conventional methods. Several studies have shown that the load capacity of this system is typically governed by punching shear strength, although no design-oriented equations have yet been developed to predict failure load or deflection at service. In this paper, two simple design equations are proposed for the ultimate load and stiffness of concrete deck slabs with SIP FRP forms, derived from the results of a comprehensive parametric study using a rigorous finite-difference computer model that is readily available. The equations were then validated by using experimental results from a database of 52 tests reported in the literature including FRP SIP forms of several shapes, sizes, surface treatments, spliced connections, boundary conditions, environmental exposures, and loading protocols. The equations showed an average predicted-to-experimental nominal strength of 87% with a standard deviation of 19%. When applying the design code member resistance factor of 0.75 consistent with shear failure of FRP-reinforced decks, a conservative strength was predicted for the entire database. Stiffness, on the other hand, was less accurately predicted; however, the model provided reliable and accurate indication of whether deflection limit is satisfied or not.