Novel reliability-based design formulation for evaluating transmission and anchorage lengths in prestressed concrete elements

This work proposes two new formulations for designing both transmission and anchorage lengths in prestressed reinforced concrete members. Such two length values represent, respectively, the distance required to transmit completely the prestressing force in the concrete, and the overall distance needed to fully anchor the tendon force in the concrete at the ultimate limit state. The two formulations proposed here are based on a reliability-based design, starting from the equations discussed within the fib TG2.5 “Bond and Material Models” and from the current approach present in the fib MC2010. For such scope, two datasets were collected, one for each investigated variable, which comprise more than 1000 experimental evidences from literature. The collected results were used to carry out a probabilistic calibration of the two formulations, and to evaluate the model uncertainty for both the investigated cases. Lastly, suitable coefficients are proposed to compute the two lengths, targeting to the required reliability level.