For a user-defined bar, the effective development for any point along the bar is calculated in accordance with the following figure.

• The end of any user-defined bar that is close to a slab edge such that it could not be extended and that has a 180 degree hook will use a desired extension length of zero. For other situations, the desired extension length is 1.125 d, the effective depth of the member
• For any length less than the desired extension length, the effective development is zero.
• For any length greater than or equal to the additional extension length, but less than the full development length, the effective percentage development is (provided length - desired extension length) / (full development length) x 100%. This is accomplished by considering a fraction of each bar developed.
• For a program designed bar, when the bar is detailed the bar will be extended the full development length plus the desired extension length. If a bar is unable to be extended this full desired length, Concept will attempt to extend the bar the 90 degree hook development length plus the desired extension length, then the 180 degree development length plus the desired extension length, then the 180 degree development length with no extension length. If there is not enough extension space to satisfy any of these conditions, an "anchor" will be placed at the end of the bar and it will be considered fully developed from that point.

Basic anchorage length is calculated using clause 8.4.3:

where

σsd	=	design yield stress of the bar $=\frac{f_{yk}}{{\gamma }_m}$
φ	=	diameter of the bar
fbd	=	ultimate bond stress given by equation 8.2

The design anchorage length is calculated in accordance with 8.4.4:

lbd = α1 α2 α3 α4 α5 1b,rqd ≥ 1 b,min

where

α1	=	bar shape factor from Table 8.1
α2	=	concrete factor from Table 8.1
α3	=	1.0 (transverse reinforcement not considered)
α4	=	1.0 (transverse reinforcement not considered)
α5	=	1.0 (transverse pressure not considered)

l_b,min ≥ max {0.31_b,rqd, 10φ, 100mm}

For beams, the minimum cover c_d is assumed to be 25 mm. As such, the minimum clear spacing between bars should be detailed as 50 mm.

For slabs, the minimum cover c_d for straight bars is calculated as the minimum vertical clear cover to the nearest concrete surface. For bent bars the cover c_d is calculated as 5 times the bar diameter. The minimum clear spacing between bent bars should thus be detailed as 10 times the bar diameter.

Anchorage length for bent bars is determined using Figure 8.1(a) and using the minimum bend diameters from Table 8.1N(a)

A concrete density factor calculated in accordance with equation 11.1 is applied to the calculation of f_bd in equation 8.2.

In addition, the following factor (from ACI 318) are applied:

• coating factor
  • 1.5 for epoxy coated bars with cover (to center of bar) less than 3db (spacing is not calculated)
  • 1.2 for all other epoxy coated bars
  • 1.0 for uncoated bars