Study of creep test and creep model of hydraulic concrete subjected to cyclic loading

Abstract

Although the structure of hydraulic concrete depends on the history of cyclic loading and unloading, most studies focus on a single loading and unloading creep test, rendering dubious the assumptions of elastic creep theory. To clarify this situation, we designed uniaxial tensile and compressive cyclic loading and unloading creep tests and implemented them under uniform conditions. The tests were done with two-grade concrete with a water/binder ratio of 0.5, which is typical of a concrete dam project. The results elucidate how creep in sealed dam concrete depends on tensile and compressive cyclic loading and unloading. The Boltzmann superposition model was then used with the Grey Wolf Optimization algorithm to determine the parameters of the eight-parameter tensile and compressive creep model. The results show that the tensile specific creep is about 1.5–2.5 times greater than the compressive specific creep at the same loading age. When the compressive specific creep is superimposed during unloading for either tensile or compressive specific creep, the goodness of fit between the specific creep curve calculated by Boltzmann superposition and the measured specific creep curve exceeds 0.85. The results of this analysis indicate that when the compressive specific creep is superimposed during unloading, the specific creep calculated based on Boltzmann superposition is consistent with the measured specific creep.