Testing and Analysis of Partially Composite Fiber-Reinforced Polymer-Glulam-Concrete Bridge Girders

Abstract

A dowel-type shear connector for achieving composite action in glulam bridge girders supporting a concrete deck is described. Direct shear tests of the connector show that its ultimate capacity is unaffected by fatigue, but that gaps do develop between the dowel and glulam after load cycling. Two 10.7-m-long glulam girders reinforced on the tension face with a fiber-reinforced polymer (FRP) and having composite concrete decks were loaded to failure after being subjected to fatigue cycling. The test results indicate stiffness increases of over 200% and strength gains of over 60% relative to the expected response of a noncomposite girder. Measured flexural strains showed a strain discontinuity at the glulam-concrete interface, as expected. A numerical model for rigorously analyzing FRP-glulam-concrete girders is overviewed, and its predictions are shown to compare favorably with the results of the girder tests. Finally, the design of a 21.3-m-span FRP-glulam-concrete bridge that is slated for completion in Fairfield, Maine, during the summer of 2003 is discussed to demonstrate the practical application of the results presented in this manuscript.