This paper presents an experimental research work to evaluate prestress losses in pretensioned 12 prestressed concrete. An experimental program including variables such as concrete mix 13 design, specimen cross-section size and concrete age at the prestress transfer was carried out. 14 Several pretensioned prestressed concrete prismatic specimens were made and tested using 15 the ECADA+ test method, based on measuring prestressing reinforcement force. In addition, 16 specimens were instrumented to obtain the longitudinal concrete strains profiles at any time. 17Measurements from both techniques were taken over one year. Measured prestress losses 18 included elastic shortening losses and time-dependent losses due to concrete shrinkage and 19 creep. A coefficient to account for the relationship between the prestress losses from the 20 measured prestressing forces and the actual prestress losses from concrete compressive strains 21 is proposed. The experimental results were compared with the predicted prestress losses using 22 methods from several codes. 23 Keywords 24Concrete, pretensioned, prestress loss, creep, shrinkage, transfer, strain 25 26 2

12Pretensioned concrete members are designed and manufactured by using at least two 13 materials: concrete and prestressing reinforcement. Also, two main stages must be considered: 14 prestress transfer and member loading. Hence, the behavior of these members depends 15 strongly on the reinforcement-to-concrete bond performance and prestress losses. In this 16paper, a testing technique to measure the specific parameters related with the involved 17 phenomena is presented. The testing technique is based on the analysis of series of specimens 18 varying in embedment length to simulate several cross sections at only one end of a 19 pretensioned concrete member. Each specimen is characterized by means of the sequential 20 release of the prestress transfer (detensioning) and the pull-out (loading) operation. The test 21 provides data on prestressing force, transmission length (initial and long-term), anchorage 22 length (without and with slip), reinforcement slips, bond stresses, longitudinal concrete 23 strains, concrete modulus of elasticity, and prestress losses (instantaneous and time-24 dependent). 25 *Manuscript Click here to view linked References 2