Bond of 13 mm prestressing steel strands in pretensioned concrete members

This paper presents an experimental research work to determine both the transmission and the anchorage lengths of seven-wire prestressing steel strands in different concrete mixes. A testing technique based on a bond behavior analysis by measuring the force supported by the prestressing strand on a series of specimens with different embedment lengths has been used. Relationships between the average bond stress for both the transmission length and anchorage length as a function of the concrete compressive strength have been found. Equations to compute transmission and anchorage lengths of 13 mm prestressing strands have been obtained. The experimental results have been compared with the theoretical prediction from proposed equations in the literature and with experimental results from other authors.

► Bond performance has been analyzed by the measurement of the strand force supported.
► Concrete strength affects the transmission and anchorage lengths of strands.
► Both [bond stress–fci] relationships in transmission and anchorage have been found.
► Equations to predict transmission and anchorage lengths have been proposed.
► Comparisons with existing equations and results from other authors have been analyzed.