This section presents an overview of the development length calculations performed in RAM Concept .

Development length calculations in RAM Concept can be treated as per Code Rules, or development lengths can be specified by the user for a particular reinforcing bar as a multiple of the bar diameter.

The general implementation used for calculating development lengths is:

• The clear spacing of the bars will be detailed to be greater than twice the minimum cover. This is the responsibility of the user, and is not checked by RAM Concept .
• Each Code has a desired extension length beyond the theoretical cutoff point of the reinforcement.
• The desired extension length for ACI 318, BS 8110, and IS 456 is the maximum of d (effective depth) or 12 times the diameter of the bar. This is required primarily because diagonal tension cracks in a flexural member without transverse shear reinforcement may shift the location of the calculated tensile stress in a bar approximately d (effective depth) towards a point of zero moment. Refer to ACI 318 12.10.3, BS 8110 3.12.9.1, and IS 456 26.2.3.1.
• For AS 3600-2001 and AS 3600-2009, the desired extension length, D, is used to satisfy provision 8.1.8.1 (2001) or 8.1.10.1 (2009). While this implementation is not in strict compliance with the Code provisions near the ends of a member, it meets the design intent away from the ends. For AS 3600-2018, no additional extension length is provided. In this standard this effect is handled more directly by modifying the strength design forces on the cross section to account for the level of shear/torsion.
• For EC2, the desired extension length is 1.125 d (effective depth). This is equivalent to EC2-04 equation 9.2 assuming cot θ = 2.5 and z = 0.9d. This is slightly conservative for members without shear reinforcement.
• For CSA A23.3-04, no additional extension length is provided. In this standard this effect is handled more directly by modifying the strength design forces on the cross section to account for the level of shear/torsion.
• For a user-defined bar, the effective development for any point along the bar is calculated in accordance with the following diagram. This approach is not used for AS 3600 or EC2 - see AS 3600-2001 and AS 3600-2009 Development Lengths and EC2 Development Lengths , respectively, for more details.
  • The end of any user-defined straight bar that is close to a slab edge such that it could not be extended will use a desired extension length of zero.
  • The end of any user-defined bar that has a hook or anchor (regardless of proximity to slab edge) will use a desired extension length of zero.
  • For any length less than a code specified minimum development length (e.g. ACI 318-14 25.4.10.1), the effective development is zero.
  • For any length greater than or equal to the maximum of the desired additional extension length and code minimum development length, but less than the full development length, the effective percentage development is (provided length)/(full development length) x 100%. This is accomplished by considering a fraction of each bar developed.
  • For any length greater than the full development length, the effective development is 100%.

Effective development at any point along a bar.

Note: The following figure does not apply to AS3600 or EC2 - see the figure in the corresponding sections.

• When laying out program-designed bars, RAM Concept uses the first option in the following list that fits in the slab (except AS3600 or EC2):
  • Straight bar end with full development length and full extension length.
  • Straight bar end with full development length and partial (or no) extension length.
  • 90 degree hook bar end with 90 degree hook development length
  • 180 degree hook bar end with 180 degree hook development length
  • 90 degree hook bar end with 90 degree hook development length with assumed confinement reinforcement factor = 0.8 (ACI 318-14 and 318-19 only). RAM Concept does not design the required confinement reinforcement.
  • 180 degree hook bar end with 90 degree hook development length with assumed confinement reinforcement factor = 0.8 (ACI 318-14 and 318-19 only). RAM Concept does not design the required confinement reinforcement.
  • Anchored bar end with no development length
• If the end of a bar is closer to a slab edge than the specified end cover, the bar will automatically be labeled "anchored" in RAM Concept and considered to be fully developed.
• Development lengths of bars in compression are not considered. Tension development lengths are used in all locations where development of reinforcement is required, regardless of the actual stresses on the reinforcing bar.