Experimental and numerical investigation on cyclic triaxial behavior of self-compacting concrete subjected to freeze-thaw damage

摘要

The freeze-thaw (FT) damage of concrete is one of the most important durability problems in cold regions, and the concrete subjected to FT damage is vulnerable to cyclic triaxial loads. Hence, the main triaxial behaviors of self-compacting concrete after different FT cycles (0, 50, 100, 150, 200, 250 FT cycles) are studied by experimental analysis and numerical simulation. The results show that with the accumulation of FT damage, the main fracture of concrete under cyclic triaxial loads gradually deflects to the direction of axial compression (σ_1), the shear failure continues to weaken, and the elastic modulus E_s, peak strength σ_(peak) and residual strength σ_(res) all show a downward trend, and both σ_(peak) and σ_(res) have a good linear fitting relationship with the number of FT cycles. In addition, with the increase of shear plastic strain, the elastic modulus and dilatancy angle decrease exponentially, while the damage variable increases in S-shape. On the basis of experimental research, the influence indexes of FT damage (consisting in the attenuation laws of elastic modulus, strength and dilatancy angle) are introduced into the model parameters, and a triaxial DEM model considering the shape of the real aggregate is established, which can well estimate the cyclic triaxial mechanical response of concrete subjected to different FT cycles.