Mechanical properties and damage constitutive model of concrete under low-temperature action

Abstract

• Mechanical properties of concrete subjected to cyclic loading and unloading after low-temperature action are studied. • A damage constitutive model of concrete after low-temperature action considering temperature and load effects is proposed. • Variations of the damage amount of concrete with strain are investigated. To study the effect of temperature on the mechanical properties and damage characteristics of concrete, a static uniaxial compression test, splitting tensile test, and cyclic loading and unloading tests were conducted on concrete specimens cured for three different periods (3 d, 7 d, and 28 d) under three different temperatures (20 ℃, −10 ℃, and −15 ℃). Subsequently, a damage constitutive model and a damage evolution equation for the concrete at different temperatures were established based on the equivalent effect variation hypothesis, Weibull and Lognormal distribution statistical theory. The stress–strain curves of the concrete specimens at different temperatures were found to be similar at the same age, all of them exhibiting five stages. With decreasing temperature, the mass loss rate of concrete increased, whereas the longitudinal wave velocity, compressive strength, and splitting tensile strength decreased. Under cyclic loading and unloading, the loading modulus of concrete at different temperatures and curing ages was slightly lower than the unloading modulus in the last loading and unloading cycle. The input energy density required for concrete cured for 3 d and 7 d at different temperatures was less than that required for concrete cured for 28 d. The findings of this study provide a reference for the analysis and design of concrete structures following low-temperature action.