Cracking moment of rectangular reinforced concrete sections corresponding to the bi-linear stress-strain diagram of concrete

Abstract

The determination of the cracking moment is an important content when designing reinforced concrete structures working in aggressive environments or having advanced requirements on the impermeability and durability. This paper aims to establish a formula that allows to more precisely determine the cracking moment of
rectangular reinforced concrete sections by considering the nonlinear behavior of concrete simplified as the bi-linear stress-strain diagram according to TCVN 5574 - 2018. The analytical formula has been experimentally validated with most errors less than 7%. The paper has also calculated the cracking moment of reinforced concrete sections corresponding to different reinforcement ratios, the calculation results have showed that: (1) the cracking moment increases linearly as a function of tensile reinforcement ratio and of compressive reinforcement ratio; (2) the tensile reinforcement ratio has a great influence on the cracking moment while the influence of compressive reinforcement ratio is insignificant; (3) the approximate method presented in TCVN 5574 – 2018 significantly underestimates the cracking moment of the section, especially in the case of high tensile reinforcement ratio.

Keywords: Reinforced concrete; cracking moment; stress-strain diagram; nonlinear behavior; bi-linear diagram.