Prediction model for restraint stress and reinforcement bond strength of grouted sleeves with defects under cycling loading
In order to establish a prediction model for the bond strength between grout and rebar in grouted sleeves with defects under cycling seismic loading,the restraint system of the sleeve was analyzed,and the defects were classified according to the influence mechanism on the restraint system.The grouted sleeve specimens with defects were designed and investigated under cycling loading tests.The mathematical expression of the restraint stress of the grouted sleeve with defects was obtained.The prediction model of the ultimate bond strength of grout with defects was established by combining the mathematical expressions,and the correctness of the prediction model was verified by comparing with the test results.The results show that the imbalance of the sleeve restraint system caused by defects is an important cause of the deterioration of the sleeve bond performance.The defects concentrated on one side induce an imbalance of the sleeve restraint system,and therefore have a more significant effect on the deterioration of the bond performance than uniformly dispersed defects.As the defect rate increases,the failure mode of the specimen changes from reinforcement fracture failure to reinforcement pullout failure.When the restraint system of the defective sleeve is in equilibrium,the threshold defect rate for rebar pullout failure is approximately 30%.When the defect causes a severe imbalance in the sleeve restraint system,the threshold defect rate for rebar pullout failure is only 20%.The grouted end is the weak point where the sleeve restraint is the first to fail,so defects at the grouted end are more likely to induce connection failure than defects at the mechanical end.The prediction model can provide a theoretical reference for the performance evaluation of grout sleeve with defects in seismic zone.
grouted sleevegrouting defectcycling loadingrestraint stressprediction model
NETL
NSTL
万方数据
