Freeze-thaw damage model for concrete considering a nonuniform temperature field

Studies show the temperature field inside the concrete under freeze-thaw cycling is not uniformly distributed. However, the existing indicators of freeze-thaw damage do not take into account the effect of nonuniform temperature field distribution. This study uses the loss of relative dynamic modulus of concrete D as a physical index to characterize the degree of freezethaw damage. Starting from the concrete freeze-thaw damage mechanism, a widely applicable freeze-thaw damage model that considers the nonuniform temperature field distribution inside the concrete structure is established based on Cai's model, theoretical derivations and experimental research. The accuracy and reliability of the model are verified through design tests. Finally, the application of the freeze-thaw damage model considering nonuniform temperature field distribution is determined for reinforced concrete (RC) beam-column joints under freezethaw cycle (FTC) action. The results show that the value for D is sensitive to the material coefficient & lambda;. The value of & lambda; tends to be a constant according to hydrostatic pressure theory and damage mechanics. The water-cement ratio significantly affects the temperature of the maximum freezing rate for concrete under FTC action, and the freezing rate for concrete under FTC action shows a linearly related with the quadratic power of the water-cement ratio. The freeze-thaw damage model considering nonuniform temperature field distribution can be used to accurately quantify the freeze-thaw damage of RC structures and members.