development of deformed bars
 

development of deformed bars
a reinforcing bar must be fully developed on both sides of any section in question. development begins at each end of the bar, where fy = 0, and fy reaches 60 ksi at a distance equal to the development length from the end of the bar.
if, at any section, there is insufficient development length available, consider using a hook, or else your effective fy will equal (actual development length/required development length) times fy.
the development length of bar is for the bar not to fail in bonding before yielding.
in general, for embedment length, the development length is measured from face of support to the end of the developed bar.
in flexural, it is measured from point of inflection where steel is no longer required technically.