The Long-term Performance Simulation Analysis Of Strengthening Reinforced Concrete Girder With External Bonding Under Hot And Humid Environment And Load Effect

One of the critical problems encountered by the current engineering structure is to reinforce existing and damaged structure.Adhesive reinforcement is widely applied in the current field of engineering structure reinforcement,owing to larger advantages.However,it is the reality that the long-term performance analysis and research as regarding to the field is not that comprehensive.At present,most of studies make people understand the long-term performance of adhesive reinforcement by virtue of exposure experiments presented in lab simulation environment and actual outdoor environment.On the other hand,the finite element modeling research concerning long-term performance of adhesive reinforcement under the common function of environment and load is also a few.For this reason,the paper conducts the preliminary exploration on the entire and long-term performance of reinforced concrete's adhesive reinforcement under the coupling of load and hygrothermal environment from the perspective of FEM numerical analysis by combining the “Critical Technical Study on Adhesively reinforced bridge's durability under the coupling of load and hygrothermal environment” in construction technology project of Ministry of Transport(2015318814190)and by taking an example of adhesive CFRP reinforced concrete.Based on the consideration to the long-term performance simulation analysis of adhesive CFRP reinforced concrete bridge under the coupling of load and hygrothermal environment,the paper selects GL2000 concrete creep mathematical prediction model,which has excellent overall assessment results of precision,to stimulate related concrete long-term performance in finite element analysis,selects the long-term performance of binding slippage relation between CFRP and concrete in the finite element model of broken-line binding slippage model simulation,and applies durability of CFRP sheets under the coupling of hygrothermal environment and load to ANSYS finite element simulation analysis by combining with the related experimental research.The application of a numerical method is applied to do a series simulation analysis of long-term performance for adhesive CFRP reinforced concrete bridge under eight working conditions,including hygrothermal environment(50 ? /95% RH),15-day hygrothermal environment and 0% of load,30-day hygrothermal environment and 0% of load,90-day hygrothermal environment and 0% of load,180-day hygrothermal environment and 0% of load,15-day hygrothermal environment and 30% of load,30-day hygrothermal environment and 30% of load,90-day hygrothermal environment and 30% of load,and 180-day hygrothermal environment and 30% of load.The result shows that hygrothermal environment has no big influence on late rigidity on CFRP reinforced bridge.Under the single-hygrothermal environment,midspan deflection of bridge presents the trend to reduce with the increase of days of hygrothermal environment.The maximal measurement of CFRP shows the reinforcement effects of bridge.Under the single hygrothermal environment,the maximal measurement of CFRP for CHT30d-0%,CHT90d-0% and CHT180d-0% presents the trend to reduce by-3.61%,-2.35%,-5.01% by comparing with CHT15d-0%.On the other hand,under the influences of hygrothermal environment and load,the maximal measurement of CFRP for CHT15d-30%,CHT30d-30%,CHT90d-30% and CHT180d-30% presents the trendy to reduce by-2.60%,-3.68%,-3.74% and-7.10% by comparing with CHT15d-0% under the single hygrothermal environment,indicating that under the single hygrothermal environment,CFRP reinforcement presents the trend to reduce.Under the influences of hygrothermal environment and load,the reduced degree of CFRP reinforcement is larger than the reduced degree under the single hygrothermal environment.Meanwhile,under the same level of load and different length distribution along binding power of adhesive CFRP reinforced concrete bridge different days of hygrothermal environment and load level,the more days of hygrothermal environment are,the larger range of adhesive shear stress ranges in the experimental area will be.Meanwhile,the biggest peak binding power near the midspan is reduced with the increase of days of hygrothermal environment to some extent.It can be observed from the slippage situation on the end of CFRP sheet hat under the situation of smaller load level,load-end slippage relation of experimental bridges is basically equal.Moreover,the slope of a curve is gradually improved with the increase of load.Under the hygrothermal environment,slope of the curve for softened stage of CHT15d-0% and CHT15d-30% is the minimum,and curve length is also shorter.Under the influences of hygrothermal environment and load,the softened stage of CFRP reinforced bridge is longer than the softened stage under the single hygrothermal environment,and the finishing time of the stage is later.At last,the paper carries out three point bending tests for two working conditions of 15-day hygrothermal environment and 0% of load and 15-day hygrothermal environment and 60%(60?/95% RH)for adhesive CFRP reinforced bridge and sets up three points bending tests without reinforced bridge in the indoor temperature to contrast,obtaining midspan load—deflection curve,yield load,damage process and failure mode of reinforced bridge.In addition,the paper discusses the failure mechanism in line with damage process and failure mode,makes a comparison between midspan load—deflection curve and finite element simulation result under the same environment,as well as verifies the accuracy of finite element simulation analysis.