Study On Mechanical Performance Of Gfrp-Concrete Composite Bridge Decks

Due to its lightweight, high strength, corrosion resistance and otheradvantages, FRP materials have become a new alternative material for bridgedecks in recent years. In spite of all these advantages, FRP components havebeen limitedly used in structure applications because of their higher initialcosts and lower stiffness than conventional materials. To overcome thisobstacle and to make the best use of materials, combinations of FRP andtraditional materials such as concrete or steel have recently been investigatedby some researchers. The advantages of hybrid structural systems include thecost effectiveness and the ability to optimize the cross-section based onmaterial properties of each constituent material. Based on the researchachievements of other scholars, this study presents a new concept for a hybridFRP-concrete bridge superstructure system. Three rectangular GFRP boxsections were bonded together to form the tensile layer, and a layer ofconcrete was placed in the compression zone of those sections. Between thetwo materials the GFRP T-upstands (bonded by two inverted L-upstands) andglued sand were used to strengthen the connections. The design was proposedin order to make the best of each constituent material. It has higher stiffnessthan GFRP composite structures but with lower costs. Meanwhile, the GFRPcomponent can substitute as formwork to simplify construction.Stiffness and strength and other mechanical properties of the hybridGFRP-concrete bridge deck were tested through static load test. The resultsshow that the new hybrid GFRP-concrete bridge deck has a good integrity,mechanical properties and stability. A finite element model was used tosimulate the process of exerting loads, and the results were compared withexperimental results. The comparison shows that the finite element modelcan accurately simulate the whole loading process of hybrid GFRP-concretebridge deck. The finite element parameters analysis indicates that increase ofthe concrete strength and concrete thickness can also increase the stiffness and load bearing capacity of the hybrid bridge deck obviously. However,considering various factors, the method of increasing the concrete strengthshould be preferred. The simulation shows, compared to the reinforcedconcrete bridge deck, the hybrid deck may have great safety reserve, andcompared to the pure GFRP bridge deck, the hybrid GFRP-concrete deck has alarger stiffness. The simulation also shows that the failure of the hybridGFRP-concrete bridge deck is due to the compression of concrete, but theGFRP material at this time is much less than its tensile strength. Therefore,though it is a brittle failure, the hybrid deck may have great safety reserve.The computation theory for midspan deflection, loading capacity for flexuralor shear of hybrid GFRP-concrete bridge deck were studied withoutconsidering the sliding effects between the GFRP and concrete. The suggestedformula and test results agree well before sliding. This study proposed adesign method of hybrid deck interface connection, and compared weight andcost among hybrid GFRP-concrete deck, pure GFRP deck and prestressedconcrete deck.This study shows that with a comprehensive consideration of weight, cost,stiffness and other factors, hybrid GFRP-concrete bridge deck is a betterchoice in bridge engineering application.