Experimental Study On Shear Strength Of RC T-beam Strengthened By Steel Jackets

As a new reinforcement technology,prestressed steel jackets(PSJ)can effective enhance the seismic performance of reinforced concrete members. The PSJ reinforcement technology has wide application prosprct in the field of structural rehabilitation.This paper adopts prestressed steel jackets reinforce the T-beams of shear capacity,focus on the feasibility of the PSJ construction. Then we finished the experimental study on the shear behavior of RC T-beams strengthened with PSJ.Finally, the design equation of the shear strength was proposed based on the truss-strut model and the result of experimental. The key to carry out the following work:(1) The 4 group of steel plates welding screw on both ends pull-out specimens were tested. Study on the tensile properties of the steel plate strip about the different weld lap length between steel plate strip and loading screw. Test results show that when the weld length between the steel plate strip and screw is greater than or equal to 100 mm, the steel palte strip would be pulled off and there was no damage about the weld.(2) The long-term strain monitoring of different levels of PSJ. Test results show that after two hours the prestress of PSJ would be partially loss, the maximum not more than 16%. The prestress loss was not obvious after more than 2h, which indicates that the reinforcement method is reliable and can ensure the long-term and effective prestress.(3) The experimental study on the shear behavior of six RC T-beams and one control beam without strengthened is carried out. The main research is the effect of the characteristic value and the prestress level of PSJ on the strengthening effect or the shear strength. The test results show that: the welding was reliable and the anchorage failure was not occurred. All specimens showed shear failure mode. The reinforcement beams ultimate shear bearing capacity was the maximum increase of46%, and the shear capacity with the stirrup characteristic value increases,but withthe stirrup characteristic value exceeds a certain value,the bearing capacity increase amplitude decreases. The reinforcement technique can effectively inhibit the development of shear cracks but It was few influence of the shear capacity about prestress level.(4) The shear strength and shear capacity of RC beam strengthened by PSJ were analyzed based on the truss-strut model. The calculation formula of shear capacity was proposed and the results were in good agreement with the experimental.