Seismic Performance And Acoustic Emission Damage Assessment Of Fabricated Shear Wall Strengthened With Steel Plate With Insufficient Grouting Material Strength

The grouting sleeve connection method has been applied in fabricated shear wall structures due to its advantages of the short construction period,and convenient construction.In the construction process of the sleeve of the engineering practice,there are phenomena such as negligent management and poor construction refinement,and the grouting material strength cannot meet the relevant standards.When the actual grouting material strength in the sleeve cannot meet the requirements of structural safety and functional requirements,it is necessary to strengthen the connection node parts.Based on this,the effect of insufficient grouting material strength on the bonding performance of grouting sleeves was investigated in this study.The fabricated shear walls with insufficient strength were strengthened with steel plate in three different ways,and the seismic performance of the shear walls was investigated through the pseudo-static test(Horizontal low cycle repeated),the acoustic emission(AE)technology was used to evaluate the damage process of the grouted sleeve and shear wall specimens.The main works of this thesis are listed as follows.The effect of grouting material strength on the bond strength of different forms of sleeves was studied.The damage evaluation of the bond failure process of the grouted sleeves was carried out relying on AE technology.Results demonstrated that the bond strength between rebar and grouting material will increase with the increase of the grouting material strength,the relative displacement between the rebar and grouting material was generated after the hardening stage of the tensile process,when calculating the bearing capacity of the sleeve against bond failure,the corresponding k value of Ductile iron sleeve was 2.65,and that of Carbon steel sleeve was 2.49.The rapid increase of the AE ringing count and energy level could be a precursor to the occurrence of bond failure of the grouted sleeve.Based on the AE intensity analysis method,the safety zone corresponding to the normal tensile process and the failure zone which predicted the failure of the sleeve bond were proposed.The fabricated shear wall with insufficient strength was strengthened with steel plates in three different ways,and the seismic performance of the specimens strengthened with the steel plate was studied through the pseudo-static test.The results showed that the expansion of cracks in the shear walls was limited effectively and the damage degree of the specimen was reduced by the steel plate strengthened method,the first crack in the specimens under different working conditions had appeared at the top section of the grouted sleeve,the cracking load was unaffected by insufficient grouting material strength,while the peak load of the shear wall specimens was significantly affected,and the peak load of the specimen of insufficient grouting material strength was about 80.05%of the specimen of normal grouting material strength.The cracking load of shear wall specimens strengthened by steel plates was significantly improved,and the peak load of those was 103.2%,105.2%,and 104.2%of the normal grout material strength specimen,respectively.The ductility,stiffness and energy dissipation capacity of the specimens strengthened by steel plates were restored to the level of normal grouting material specimen.The damage evaluation of the destruction process of shear walls under pseudostatic loading using AE technology.The results showed that the AE energy,History index(HI),Serious index(Sr)and Improved b(Ib)values could better characterize the crack expansion and damage evolution of shear wall specimens under repeated loading,the cumulative AE energy,and cumulative energy dissipation trends over time had a good correlation.Based on the Park-Ang damage model,the damage model of shear walls under repeated loading was established by combining AE cumulative energy,and the trend of damage index calculated by this damage model was more consistent with the trend of damage state evolution of shear walls,and the maximum value of damage index was 1.The proposed damage model can effectively evaluate the damage degree of shear wall specimens under cycling loading.