EVALUATION FOR APPERENT INSTANTANEOUS STIFFNESS DECREASE CONSIDERING EFFECT OF CREEP OF EARLY AGE CONCRETE

Abstract

In the thermal stress analysis, the effect of creep is considered as an apparent instantaneous stiffness decrease using the effective Young’s modulus which is Young’s modulus multiplied by a reduction coefficient. However, the reduction coefficient is used same value regardless of the type of cement, the mix proportion of concrete, the temperature history, etc. In this study, the purpose is to evaluate the effect of concrete temperature on the reduction coefficient for Young’s modulus. We conducted experiment using thermal stress testing machine with temperature history as a factor, and obtained the reduction coefficient. As a result, it was confirmed that reduction coefficient for Young’s modulus shows different values depending on the temperature history. In addition, it was confirmed that the value was highly correlated with the rate of temperature rise, the maximum temperature, and the period of tensile stress.