Multi-scale Computational Modeling on the Equivalent Element Method for Freeze-thaw Damage of Concrete

Frost damage is one of the main reasons for the decay of concrete in cold regions, which is affected by many factors such as freezing temperature, number of freeze-thaw cycles (FTCs), pore and aggregate structure, and the FTCs damage in concrete presents a certain distribution characteristic. In view of this, a systematic prediction method for FTCs damage distribution was established by the multi-scale method. Firstly, the FTCs damage behavior was simulated by the micro-calculation method. Subsequently, the micro-meso-macro multi-step equivalent method was established for the description of FTCs damage, and the equivalent element of concrete under FTCs was established. The calculation results of the equivalent model show that the characteristic element size should be set as 10 mm to 20 mm, which can satisfy the requirements of the heterogeneous characteristics of FTCs damage and Weibull distribution at the same time. Meanwhile, the effects on the FTCs number and freezing temperature of the FTCs damage distribution were discussed, and the effectiveness of the equivalent element was verified by comparing it with the test results, which the equivalent calculation model can well describe the heterogeneous distribution of FTCs damage.