Study On The Bond-slip Mechanism Of FRP-concrete Interface Under The Influence Of Macroscopic Cracks

Fiber reinforced polymer(FRP)is more and more widely used in the field of civil engineering.In practical engineering,there are often encountered the situation of concrete structures strengthened with FRP existing macroscopic cracks.However,the research on this issue that the bond-slip mechanism of FRP-concrete interface under the influence of macroscopic cracks is still relatively small,it is urgent to study.In this paper,in order to solve this problem,the author makes a preliminary study on the bond-slip mechanism of FRP-concrete interface under the influence of macroscopic cracks.The main research contents and conclusions in the paper are listed as follows:(1)By studying research papers of many domestic and foreign researchers who study on the application of FRP in field of civil engineering,the FRP cloth fixture(steel loading fixture)what can effectively solve the technical difficulties to let the FRP-concrete interface always to be in pure shear stress state under loads was developed,and the finite element analysis was carried out on it to verify that it meets the test requirements.An optimized double-shear loading scheme was put forward to ensure that the double-shear test of FRP-concrete interface under static loads can be carried out smoothly.(2)Based on the relevant research,the bond-slip constitutive model of FRP-concrete interface under the influence of macroscopic cracks was put forward through the theoretical analysis and a lot of trial.(3)Through the static load test of FRP-concrete interface,the loading process,failure process and failure mode of FRP-concrete interface under the influence of macroscopic cracks under static loads were observed,the operation program of relevant test data was compiled with MATLAB software,the stress transfer law of FRP-concrete interface,the mechanism of interfacial bond failure and the evolution of interfacial slip under the influence of macroscopic cracks were studied.By fitting and analyzing the experimental data,the bond-slip constitutive model of FRP-concrete interface under the influence of macroscopic cracks under static loads was established with MATLAB software,it was also compared with other existing models proposed by other researchers.Meanwhile,by analyzing and comparing the experimental data,the influence area of macroscopic cracks was analyzed.(4)Based on the bond-slip constitutive model of FRP-concrete interface under the influence of macroscopic cracks under static loads by the experiment,the bond-slip finite element model of FRP-concrete interface under the influence of macroscopic cracks was established by ABAQUS software which proves the validity,rationality and accuracy of the proposed model.Meanwhile,by analyzing and comparing the bond-slip finite element model of FRP-concrete interface under the influence of macroscopic cracks under static loads,the influence of macroscopic cracks on the interfacial bond-slip relationship was studied,the defect that the interfacial bond-slip relationship of only a few points on the specimens can be obtained and the strain variation of concrete specimens in the loading process can not be intuitively understood through the experimental study on the bond-slip relationship of FRP-concrete interface under the influence of macroscopic cracks was made up.(5)By analyzing the experimental study and finite element model of the bond-slip constitutive relationship of FRP-concrete interface under the influence of macroscopic cracks,corresponding laws were summarized,corresponding basis and recommendations of design and construction on strengthening concrete structure with FRP were provided under the premise of concrete structure existing macroscopic cracks in civil engineering design and construction.