Based on the assumptions that a plane section before bending remains a plane after
bending and no relative movement takes place between steel and concrete, an expression for the
flexural rigidity of steel reinforced concrete (SRC) beams as a function of the rigidities of steel and
concrete was derived. The approximate and simplified formulas for calculating the flexural rigidity of
SRC beams were proposed based on the expression, the relevant formulas given in the Chinese
current design codes for concrete structures, the approximate position of neutral axis and the
approximate stress factor of the reinforcement including the tensile flange of steel. The proposed
formulas agree well with experimental results and may be used as a reference for structural
engineers.