Free-length failure tests of strand samples (that is, tensile
tests performed using special sand-grip anchors to achieve
strand failure within the free length away from the anchorages)
conducted by Walsh and Kurama31,32 showed that
the true (that is, not affected by the anchorages) ultimate
fracture strain capacity of seven-wire, low-relaxation posttensioning
strand is generally between 0.060 and 0.075.
Thus, the strain limit of 0.01 as governed by individual
wire fractures inside the anchorages is restrictive relative to
the actual material capacity of the strand.