Dynamic mechanical characteristics of concrete affected by loading rate

摘要

Concrete is a typical kind of artificial synthetic material with complex engineering features; thenloading rate will result in the change of material rupture shape. There is a critical velocity duringnthe breakage process of materials with a transition from plasticity to brittleness. The uniaxialncompression virtual test of numerical concrete with cracking function of the aggregate is done byncompiling program by means of embedded fish language under particle flow code condition. Theninput parameters of the numerical model, i.e. strength and deformation of mortar and aggregate,nare tested through tensile strength, compression strength and modulus tests of mortar andnconcrete, and cohesion strength test of interface between mortar and aggregate. Then, uniaixalncompression tests with six different loading rates such as 0?0005, 0?0010, 0?0020, 0?0050, 0?0100nand 0?0200 m s21nare designed to study the effect of the loading rate. Moreover, the influence ofnrupture process, crack number and propagation, curve of stress and strain, energy transforma-ntion done by the loading rate is analysed based on these tests. It was found that an increase in thenloading rate damages the development of the superior shear zone, which makes the shear zonenexpand with the same velocity, and the failure of concrete appears as splitting damage with morenvertical cracks. The loading rate enhances the mechanical behaviour and deformation features ofnmaterials with uplifting of slope and peak value. The total cracks increase with decreasing tensilencracks and increasing shearing cracks. Boundary energy enhances, friction, kinetic and strainnenergy increase monotonically, which illustrates increases in shear cracks and violent failure andnrockburst of side.