Dynamic mechanical characteristics of concrete affected by loading rate

Abstract

Concrete is a typical kind of artificial synthetic material with complex engineering features; the loading rate will result in the change of material rupture shape. There is a critical velocity during the breakage process of materials with a transition from plasticity to brittleness. The uniaxial compression virtual test of numerical concrete with cracking function of the aggregate is done by compiling program by means of embedded fish language under particle flow code condition. The input parameters of the numerical model, i.e. strength and deformation of mortar and aggregate, are tested through tensile strength, compression strength and modulus tests of mortar and concrete, and cohesion strength test of interface between mortar and aggregate. Then, uniaixal compression tests with six different loading rates such as 0·0005, 0·0010, 0·0020, 0·0050, 0·0100 and 0·0200 m s⁻¹ are designed to study the effect of the loading rate. Moreover, the influence of rupture process, crack number and propagation, curve of stress and strain, energy transformation done by the loading rate is analysed based on these tests. It was found that an increase in the loading rate damages the development of the superior shear zone, which makes the shear zone expand with the same velocity, and the failure of concrete appears as splitting damage with more vertical cracks. The loading rate enhances the mechanical behaviour and deformation features of materials with uplifting of slope and peak value. The total cracks increase with decreasing tensile cracks and increasing shearing cracks. Boundary energy enhances, friction, kinetic and strain energy increase monotonically, which illustrates increases in shear cracks and violent failure and rockburst of side.

Keywords:

• Particle flow
• Concrete
• Loading rate
• Rupture shape
• Crack
• Energy