Experimental Technique for Measuring the Long‐term Transfer Length in Prestressed Concrete

  This article presents a proposal of a test set‐up and methodology for testing the transfer length evolution through time of prestressing reinforcement in pretensioned prestressed concrete members, aimed at providing a basis for standardization. The proposed test method is based on the instantaneous and time‐related analysis of the prestressing reinforcement force profile at only one end of a pretensioned prestressed concrete member. The basis of the test method and the requirements of the prestressing frame and its components are presented, as well as the test procedure stages and the measurement devices. The interpretation of the test results and the criteria to determine both the initial and the long‐term transfer lengths are explained. A test method application and the equipment for testing seven‐wire prestressing strands have been designed. Some experimental results are provided to validate the test. A comparative analysis of test reliability with other existing experimental methods is also included.