Splices of FRP Stay-in-Place Structural Forms in Concrete Bridge Decks

This experimental study focuses on the design and spacing of splices of fiber-reinforced polymer (FRP) stay-in-place structural forms used in concrete bridge decks. The ribbed FRP panels, which span the gap between girders, are typically of limited width, and therefore are spliced by overlapping. A total of 23 auxiliary lap splice tension tests addressed various bond systems including adhesive and/or mechanical fasteners of various diameters and spacing. Seven scaled bridge deck systems were built with FRP panels of various widths, some with bonded splices and some with no bond at all at the overlap region. The study showed that using narrow FRP plates of small width-to-deck thickness ($b/t$) ratio significantly reduces deck capacity when no splice bond is provided because narrow panels may force the punching shear crack to terminate at a splice, at a steeper angle, thereby reducing punching shear capacity. The deck with $b/t=1.9$ exhibited a 24% lower capacity than that with $b/t=7.2$. In bonded-splice decks, plate width has no effect on strength. Generally, ultimate failure loads ranged from 5.7 to 8.8 times the equivalent service load. For an overlap splice of a length equal to 4.3 times plate thickness, the optimal splice was by combined adhesive and fasteners of diameter equal to plate thickness, spaced at 1.8 times the overlap length. It developed 68% of plate tensile strength, whereas fasteners alone developed only 14–45% strength depending on their diameter and spacing.