Experimental and numerical research on cyclic tensile performance of high-strength hydraulic concrete subjected to freeze–thaw damage

Hydraulic concrete structures in cold regions are vulnerable to freeze–thaw (FT) cycles, which will significantly weaken their ability to resist tensile load, thus threatening the safe operation of structures. Direct tensile properties of high-strength hydraulic concrete subjected to different FT cycles (0, 100, 200, 300 and 400 FT cycles) are investigated through experimental analysis and numerical simulation. The results show that the tensile strength, initial elastic modulus and ultimate strain of hydraulic concrete decrease linearly with the increase of FT cycles, and the cumulative rate of residual strain is independent of FT damage, but increases linearly with the increase of unloading strain. Based on FT damage caused by temperature and mechanical damage caused by external load, a cyclic tensile model considering FT effect is proposed. Moreover, the evolutions of principal strain, main crack width and internal microcrack of hydraulic concrete subjected to different FT cycles under cyclic tensile load are revealed by digital image correlation (DIC) and acoustic emission (AE) techniques. Based on experimental analysis, a DEM cyclic tensile prediction model considering loading–unloading constitutive and real aggregate is established to accurately describe the cyclic tensile response of hydraulic concrete subjected to different FT cycles.