• In the case of bars in compression, a part of the total force is transferred by bond along the embedded length, and a part is transferred by end bearing of the bar on the concrete.
  • Because surrounding concrete is relatively free of cracks and because of the beneficial effect of end bearing, shorter development lengths are permissible for compression bars than for tension bars.
  • Hooks are not effective in transferring compression from bars to concrete, and if present for other reasons, should be disregarded in determining required embedment length.
  • The ACI code equation for basic development length in compression is

  • but not less than 0.0003dbfy. Modification factors given in table should be applied but in no case is ld to be less than 8 in.
Development Length of Deformed Bars in Compression
Modification factors to be applied to ldb 
  • Reinforcement in excess of that required by analysis  
  • Reinforcement enclosed within spiral reinforcement not less than ¼ in. diameter and not more than 4in 
    pitch or within #4 ties spaced at not more than 4in on centers.................0.75


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