Numerical Simulation On Fracture Properties Of Concrete By The Mesoscale Method

On the mesoscale level, according to the characteristics of the internal structure and composition of concrete, this can be seen as a three-phase non-homogeneous composite material consists of coarse aggregates, mortar and the band zone between these two composites. The method which is based on the mesoscale rigid body spring has good applicability in the internal simulation of concrete cracking and crack propagation, and received widespread attention. The fracture energy of concrete is parameter that characterizes the material’s ability to resist cracking, which is defined as the average energy consuming per units crack area, and it is an important parameter in non-linear fracture mechanics of concrete. The research on fracture properties of concrete can provide guidance and reliable basis for the development of the theory of structural design and concrete. Therefore, based on meso-rigid body spring method, combined with the existing experiment, considered the impact of fracture height ratio and aggregate content of the wedge splitting specimens, the paper carried out a serial of numerical simulation of fracture properties of concrete under static loading with wedge splitting specimens. Specific work and conclusions are as follows:(1) Using the meso-rigid body spring model to simulate the side length of200mm x200mm, a series of a0/D=0.2,0.3,0.4,0.5wedge splitting specimens, the numerical results were compared with the results of physical tests, the results showed that:On one hand, verified the feasibility of meso-rigid body spring model to simulate the wedge splitting specimens of concrete conducting tensile tests; on the other hand, the fracture height ratio influenced the form of damage to the specimen, the proliferation form of cracks developing, the concrete peak stress intensity and the fracture energy of concrete, which explains that fracture height ratio is an important factor in concrete wedge splitting tensile experiments.(2) The volume content of concrete aggregate also affects the fracture properties of concrete. On the basis of the wedge splitting model, using the created meso-scale rigid body spring model, discussed the effect of the volume content of aggregate on the fracture energy of concrete, and observed the mortar specimens, single aggregate specimens (aggregate volume content of6%), specimens with aggregate content of15%,37%,48%, the results showed that:The volume content of aggregate determines the size of fracture energy, higher the aggregate content specimens, more gentle the end of its P-CMOD curve slope, and the fracture energy increases as the size of the aggregate content increased; the maximum tensile strength of the mortar specimen is higher than concrete specimens, but the mortar specimens’ P-CMOD curve falls rapidly after the peak point, which means that mortar specimens has a strong brittle character, and compared with concrete specimens that mortar has no good softening properties.