Numerical Simulation Of Quasi-static And Dynamic Mechanical Behavior Of Concrete With Different Size Of ITZ

Due to wide range of raw materials, low quality, low price, and with the advantages of good durability and operability, concrete has a wide range of applications in the actual project.The mechanical properties of static and dynamic load is the premise to effective assessment of the performance of concrete structure and safety. It is necessary to understand the mechanical properties and failure process of concrete under static and dynamic loads. In this paper, the concrete is regarded as the three-phase composite material composed of coarse aggregate, cement mortar and interfacial phase. On the basis of the experiment, the finite element model was established by ANSYS/LS-DYNA, and the static and dynamic mechanical properties of concrete were simulated and analyzed. The research is as follows:(1) Using microcomputer YS-2000 servo rock triaxial testing machine and ? 74 mm straight taper variable cross-section SHPR testing apparatus for concrete and cement mortar materials for quasi-static uniaxial compression test and dynamic impact compression test. The test results show that the material stress-strain curve of concrete and cemen mortar is made up of four different stages .The other result found: concrete. cement mortar is a rate sensitive material.(2) With the aid of APD1. language in ANSYS. a random distribution program of two-dimensional concrete with round-shaped thick aggregate was prepared.According to the gradation curve fuller, navarre plane transformation formula, establishment of two-dimensional random aggregate model,Effect of concrete specimen size, interface thickness, volume percentage and particle size and distribution on quasi-static compression and dynamic impact mechanical properties of concrete:1) Quasi-static compression of concrete numerical simulation show that: (1)As with ordinary concrete, concrete containing interface has obvious size effect; (2) Interface thickness and the coarse aggregate size remains the same, as the coarse aggregate volume percent increases, concrete carrying capacity showed the first increase and then decline, the volume percentage was 40%, the concrete compressive strength; (3)The aggregate minimum size is 5 mm, the interface thickness, volume percent unchanged, as the coarse aggregate particle size increases, the largest concrete compressive strength appear when particle size increases to 20 mm maximum; (4) The particle size, volume percent,specimen size unchanged, the interface thickness increases, the compressive strength of concrete decreases.2) Concrete impact dynamic numerical simulation shows that: (1) Keep the interface thickness,volume percent and the aggregate minimum size remains the same, as the largest particle size increases,the bearing capacity of concrete showed a decreasing trend after increase first; (2) Keep the aggregate particle size, the thickness of the interface and specimen size remains the same, as the coarse aggregate volume percent increases, the concrete bearing capacity showed a trend of first increases and then; (3)Keep the coarse aggregate particle size, volume percent, and interface thickness is constant, with the increase of specimen size, the bearing capacity of concrete decreases, showing obvious size effect; (4)The specimen size, volume percent and particle size unchanged, as the interface thickness increases, the bearing capacity of concrete decreases.