Durability Study Of High Strengthed RC Beams With CFRP Under Complexed Conditions And Sustained Load

With the acceleration of urbanization in China,various kinds of buildings have been rapidly rising in recent years.With the passage of time,a large number of buildings are unable to meet the functional needs due to aging and corrosion.Therefore,reinforcement and repair of structures are needed.CFRP with high strength,corrosion resistance and convenient construction has been widely used in reinforcement and repair of reinforced concrete beams.However,reinforced components in actual engineering are often subjected to various environments,which brings great difficulties to durability research.At present,the research on CFRP-concrete is mainly focused on the bond properties of the bonding interface,or the study of the bearing capacity of the beams strengthened under single conditions.The CFRP-concrete beams coupled to the complex environment need to be further studied.Based on the National Natural Science Foundation Project "study on the durability of FRP strengthened high strength concrete under the load of complex marine environment"(51378090),the durability of CFRP-concrete beams under freezing thawing cycle,wet and hot environment and sustained load is studied in this paper.The main research contents include: CFRP-concrete beam deterioration and loading test under complex environment;analysis of bearing capacity,deflection and failure form of test beams;analysis of stress and strain of CFRP cloth and steel bars;calculation of bearing capacity of CFRP-concrete beams;finite element simulation of CFRP-concrete beams under complex environment;mechanical properties of deteriorated specimens in combination with test Analysis。Under the same environment,the ultimate bearing capacity of the specimen is reduced,and the bearing capacity of the specimen decreases as the continuous load increases.Under the action of 150 freeze-thaw cycles and 1000 h hours continuously in the environment with hot and humid,the bearing capacity of the 30% and 60% specimens decreased by 2.5% and 10.2% respectively.The continuous load will accelerate the bending resistance of the damaged concrete specimens.Compared with 150 cycles of freeze-thaw cycle,the deterioration degree of 500 h is more significant than that of 150 cycles of freeze-thaw cycles when humidity is 98%.Under the same continuous load,different freeze-thaw cycles and humid heat environment,the worse the environment is,the smaller the load capacity and the smaller the stiffness.The bearing capacity of the test beam is calculated according to the peeling failure caused by the central bending cracks.According to the test condition,a finite element model based on ABAQUS is built to simulate the stripping failure process.