Performance of a scaled FRP deck-on-steel girder bridge model with partial degree of composite action

Abstract

The applications of FRP decks have been increasingly implemented in the United States since the mid-1990s. Although extensive research has been conducted on stiffness and strength evaluations of various types of FRP decks, studies on FRP deck-on-steel girder systems are limited. The performance of the FRP deck-on-steel girder system depends substantially on the connectors used. Recently, a prototype shear connector was developed and its advantages were illustrated through both laboratory study and field applications, where partial degree of composite action could be achieved between the deck and stringers. This paper aims to study the effectiveness of the shear connector at bridge-system level, including the static and fatigue performance of the shear connector and the bridge system, the degree of composite action of the system; and more importantly, the influence of the partial degree of composite action on load distribution factor and effective flange width since no provision is provided in AASHTO Specifications. For this purpose, a 1:3 scaled FRP deck bridge model was tested, with an FRP sandwich honeycomb deck connected to steel girders using the prototype shear connector. The test program consisted of three phases: Phase I and Phase II included static and fatigue load tests on the scaled bridge model. In Phase III, a T-section was cut-out from the bridge model and then loaded under three-point bending until failure. A Finite Element model was constructed to simulate the tests. It was shown that the shear connection was able to provide partial composite action of about 25%, and sustain a cyclic fatigue loading equivalent to 75year bridge service life span. It is shown that AASHTO Specifications can still be applicable for load distribution factor, while the effective flange width needs to be re-defined for bridge-system with partial degree of composite action. The findings from this paper can be used for design purposes.