Experimental study on transfer length of prestressing strands in UHPC members

In pretensioned concrete members, a certain distance is required to transfer the prestressing force in strands to the concrete; this is the so-called transfer length, and it is dominated by bond performance between prestressing strands and surrounding concrete. Compared to the normal strength concrete, however, newly developed ultra-high performance concrete (UHPC) shows different bond characteristics of prestressing strands because it has a very dense matrix. Therefore, this experimental study was conducted to investigate the transfer length of prestressing strands in UHPC members, in which the compressive strength of UHPC and volume fraction of steel fiber were considered as the main variables. In addition, by comparing the test results with current code provisions and other models proposed by previous researchers, the applicability for estimation of the transfer length of UHPC members was examined.