Prestressed FRP Tubular Deck System

Abstract

An experimental and analytical study was undertaken to assess the behavior of a new FRP deck system. The deck consists of a series of pultruted FRP tubes, laid side by side on existing stringers, perpendicular to the direction of traffic. The tubes are then post-tensioned at mid-point between the stringers in the direction of traffic. The experimental work consisted of seven FRP tubular specimens crushed on their sides, eleven FRP decks in static bending, and four FRP decks in fatigue bending. The analytical work consisted of modeling of crushing test for a single FRP tube and multiple unbounded FRP tube specimens, modeling of static flexural test for a bonded and an unbounded FRP deck panel, and load rating of the floor system for the bridge with the installed FRP deck. The study showed feasibility of the new deck system for bridges with limited truck traffic and closely spaced stringers, where lack of panel action is not a concern. Failure mode, stiffness and capacity of the deck system are all functions of the FRP material properties and tube size, span length, interface bond and prestress level. In general, longer span decks fail in bending, whereas shorter span decks suffer from local shear failure due to stress concentrations at the corner of the tubes most adjacent to the applied load or the support. The deck system has some redundancy and reserved strength built into it by means of prestressing strand or bar. Short span decks are susceptible to early fatigue failure. The finite element analysis was shown to provide a good simulation of the FRP deck system. The floor system in the bridge was rated for 30 tons and 19 tons at the operating and inventory levels, respectively.