Study On The Effect Of High Temperature On The Tensile Properties Of Grouted Sleeve Connection

At present,prefabricated concrete structure is widely promoted and developed in the field of architecture in our country.It is quite significant to strengthen the research on the prefabricated concrete structure in our country at the present stage.As one of the important connection ways for rebars in prefabricated concrete structure,the Grouted Sleeve Connection(GSC)have been widely used in practical engineering due to its advantages of high reliability and convenient construction.At present,there are few researches on the mechanical properties of GSC under high temperature and after high temperature.However,the impact of the fire in practical engineering and the damage caused by the collapse of the structural continuity caused by the fire is enormous.Therefore,it is quite necessary and urgent to study the mechanical properties of GSSR under high temperature and after high temperature.In view of this,in order to study the mechanical properties o f GSC under high temperature and after high temperature,45 Full-Grouted Sleeve Connection(FGSC)specimens and 36 Half-Grouted Sleeve Connection(HGSC)specimens were designed and made.Then the unidirectional static tensile tests under high temperature a nd after high temperature were carried out on these 81 specimens.At the same time,45 rebars of the same batch were reserved for material tests under the same conditions.In addition,45 grout specimens with the size of 40mm×40mm×160mm were made in the same batch.After cured under the same condition with GSC specimens,the material tests were carried out to measure the flexural strength and compressive strength.The test results showed that there were two failure modes in the unidirectional static tensile test of GSC specimens under high temperature and after high temperature,which were rebars broken and rebars pulled out,and the tests under high temperature mainly caused to the failure mode of rebars broken,the tests after the high temperature over 600℃ mainl y caused to the failu re mode of rebars pulled out;For the GSC specimens with rebars broken,the tensile properties were similar to those of the rebars,and the bearing capacity was close to that of rebars.However,the bearing capacity of GSC specimens with rebars pulled out was generally lower than that of rebars;There was bond slip between rebars and grout during the tests,and the higher the temperature,the more obvious the slip phenomenon was.Based on the analysis of the bearing capacity and displacement of GSC specimens,the bond anchorage strength of some GSC specimens with rebars pulled out was calculated,and the relationship between the anchorage strength and temperature was described as fitting formulas.Based on the bond anchorage stren gth,the k value in accordance with the design specification was calculated,and the design suggestions to avoid the failure mode of rebars pulled out were given.Combined with the test results of the rebars,the bond slip of GSC specimens under the yield load and the ultimate load was analyzed approximately,and the relationship between the bond slip of GSC specimens and the temperature was described as fitting formulas.