Development Length of steel Reinforcement Bar
Development lenth is the length of the bar which is used to transfer the stress of steel into concrete.
This is mainly bend or hook length in case of beam and column, i.e. tension and compression member respectively.
Development Length is denoted by Ld
Ld = (Nominal dia of bar × stress in bar) / (4× bond stress in bar)
Thumb Rule for Development Length of bar
Generally development length is the 41 times of nominal dia of bar.
Necessity of Development length
It is necessary to make a combined material of steel and concrete, for the safely transfer of load in each other they required good bonding between each other. So development length of bar is provided to transfer the whole stress without flexural failure.