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

The steel corrosion of steel reinforced concrete caused by some environmental factors has become one of the serious problems to be solved urgently in civil engineering field both at home and abroad. The replacing steel by FRP materials in structural engineering has become one of the feasible methods to solve the steel corrosion in engineering structure.So far, the domestic researchers have not obtained an in-depth understanding of the mechanical property of FRP reinforced concrete structure under the condition of fatigue load. And the design and calculation of the FRP reinforced concrete structure under fatigue load is also imperfect.Terefore, through the fatigue load test of 4 pieces of GFRP reinforced concrete plates and the static load of 1 piece of GFRP reinforced concrete plate, the thesis studies the impacts of stress level, stress ratio, loading amplitude and times of fatigue cycles on the specimen stiffness and crack width. The main research contents and results are listed as below:(1) Analyzes the load-deflection relation of the GFRP reinforced concrete slab in case of static force loading,load-strain relationship of longitudinal reinforcement GFRP tensile area and compressed area concrete,And the slab of carrying capacity, the occurrence and development of the cracks.(2) After certain times of fatigue cycles, the static load test of the fatigue test plate showed that, with the increase of stress level and the decrease of the stress ratio, specimen of midspan deflection increases with the increase of number of fatigue, stiffness decrease with the increase of fatigue cycles. The fatigue life of specimen rapidly reduced.The strain of Longitudinal GFRP rebar and compressive zone concrete are increases considerably.This is mainly because when stress level is higher and the stress is small, the concrete with the increase of fatigue cycles have accumulated more residual deformation and fatigue damage accumulation of GFRP rebar fast.(3) Analyzed the GFRP reinforced concrete slab under fatigue load,the change of crack width and rigidity, put forward crack width and stiffness calculation formula of GFRP reinforcement concrete slab under fatigue load,through the comparison with the experimental data, the calculated results are matched very well.