### Three Stages in the Life of a Reinforced Concrete Beam

CE 331 Fall 2010 Flexure Strength of Reinforced Concrete Beams 5 5 4 Calculate φ strength reduction factor φ is a function of the strain in the steel If the strain in the steel εs is at least 2 5 times the yield strain εy 0 002 60 ksi 29 000ksi f y Es then the max value of φ 0 90 can be used