Transfer lengths of pretensioned concrete members reinforced with 2400 MPa high-strength prestressing tendons

High-strength prestressing tendons with a tensile strength of 2400 MPa have been recently developed in the steel industry of South Korea, and is currently being mass produced for common commercial applications in structural engineering practices. Accordingly, since most of the existing transfer length estimation models were derived based on the test results of the specimens having the prestressing tendons with a tensile strength of 1860 MPa or less, modifications of the transfer length models are now required to consider the effect of the enhanced tensile strength of the prestressing tendons. In this study, six pretensioned concrete specimens reinforced with 2400 MPa tensile strength prestressing tendons were fabricated and tested to investigate their transfer lengths. In addition, a simplified design equation for the transfer length was developed based on the assumption of the linear strain profile curves of the prestressing tendon and surrounding concrete in transfer length zone. The accuracy of the proposed equation was verified in detail by comparing a total of 215 transfer length test results with analysis results. The simplified design equation provided very accurate results on the transfer lengths of all the test specimens, regardless of the tensile strength grades of prestressing tendons.