Measurements of the transmission length of pre-tensioned strands

The studies on the transmission length over which the prestressing force is fully transmitted to the concrete in anchorage regions of pre-tensioned structures show very scattered results. This is due to the complexity of the phenomenon that is influenced by several parameters, among which the different characteristics of strands, with reference to mechanical strength, relaxation and surface conditions, that have changed over the last decades. On the basis of a testing procedure which can simulate most of the phenomena that occur around the pre-tensioned strand at release, an experimental campaign was carried out. The results, such as the transmission length and the draw-in of strands, are determined for various concrete strengths.