The transfer length is the distance required to transfer the force in the strand, under service loads, from a value of 0% at the end of the beam (or end of debonding, if present) to 100% of its capacity. For locations within this region, a linear interpolation is performed to compute the effective area of steel.

The development length is the distance required to develop the full capacity of the strand and is used for ultimate capacity calculations under factored loads. Since the stress under factored loads is higher, the development length is longer than the transfer length.

The basic transfer length is 50 strand diameters as specified in LFD Art. 9.20.2.4. The basic development length is calculated according to LFD Art. 9.28.

Four multipliers have been provided to simulate varying the effective transfer and development lengths for bonded and debonded strands. The default value of the development length multiplier for debonded strands is 2.0, as specified in LFD Art. 9.28.3.