Development of Reinforcement Bars

RAM Concrete Beam accounts for the loss of bar strength between the point of full bar development and the bar end. The program assumes the tensile capacity of a bar varies linearly between the point of development, at which the full yield strength of bar is achieved, and the bar end, at which zero capacity exists.

The reinforcement development length calculation follows ACI 12.2:

For d_b ≤ 0.75:

l_{d} = \frac{d_{b} f_{y} α β λ}{25 \sqrt{{f^{'}}_{c}}}

ACI-12.2.2

For d_b > 0.75:

l_{d} = \frac{d_{b} f_{y} α β λ}{20 \sqrt{{f^{'}}_{c}}}

ACI-12.2.2

where

α, β and λ

1.0 ACI-12.2.4

For lightweight concrete λ = 1.3

Thus, for a bar assigned a Straight end condition, the capacity is zero at the true bar endpoint (the coordinate shown in the View/Update dialogue) and varies linearly to the point of full development. Hooked bars are assumed to achieve the full yield strength of the bar up to bar end.