Experimental Study On Fatigue Behavior Of Concrete Slabs Reinforced With Glass Fiber Reinforced Polymer (FRP)Bars

Reinforced concrete bridge deck slabs are bearing components of bridgestructure, they are exposed to repeated vehicle loads chronically, and also bear theerosion of deicing salt and other corrosive environments, corrosion of steels isbecoming more and more seriously. Researches in recent years showed that, usingglass fiber reinforced polymer (GFRP) bars to replace the steel bars is an effectivemethod to solve the corrosion problem.Although there are many researches on themechanical properties of concrete slabs reinforced with GFRP bars under static load,there is no systematical experimental research on fatigue behavior of concrete slabsreinforced with GFRP bars at home and abroad.In order to study the fatigue behavior of concrete slabs reinforced with glass FRPcomposite bars, five GFRP reinforced concrete slabs has been designed, length1600mm,section size of450mm×100mm,one of the slabs for static test to mainlystudy the mechanical properties under static load, at the same time test the slab’sultimate bearing capacity to provide the basis for determining the upper and lowerlimits of fatigue load. The other four slabs for fatigue test, mainly examine the stressratios on compressive concrete strain, GFRP bars strain, midspan deflection, fatiguefailure characteristic, fatigue life, development of cracks and so on. The mainresearch contents as follows:(1) Under static and fatigue loads, all test slab specimens failured with fractureof GFRP bars, and belonged to brittle failure.(2) Under static and fatigue loads, slab specimens mainly formed cut-throughcracks along the width direction, and basically the cracks distributed symmetricallyabout cross section. With the increase of stress level, stress ratio reduced, themaximum crack width of slab specimens became larger.(3) With the increase of static loads, the midspan deflection, GFRP bars’ strainand concrete strain in compression zone of specimens basically showed a lineargrowth, cross section stiffness decreased greatly. Under fatigue loads, with the decrease of the stress ratio, the midspan deflection, GFRP bars’ strain and concretestrain in compression zone of specimens showed an increasing trend, section stiffnessdecreased gradually; With the increase of fatigue cycle times, the midspan deflectionof all specimens had an rising trend, GFRP bars’ strain and concrete strain incompression zone showed a curvilinear change, and the variation laws between themcorresponded, section stiffness declined quickly.(4) With the increasing of stress level, the fatigue life of concrete slabs decreasedgreatly, and reflected that the influence of stress ratio on GFRP reinforced concreteslabs was very big.