Numerical Simulation Of Shape Of Aggregates Of Three-Graded Concrete(Full-Graded Concrete) And Application

In this paper, concrete was taken as three-phase composites consisting of mortar matrix, aggregate and the bond between matrix and aggregate. The key issue of numerical concrete-simulation technology of aggregate shape was studied and the program was presented to generate two or three dimensional random aggregate shape. The failure process of concrete is simulated by means of the software-MSC.MARC developed secondly. Main work of this paper includes:1. For the characteristic of three graded or full graded concrete, whose content of the aggregate is higher (0.6-0.7) than that of normal concrete, a more effective method is presented in the paper to generate the random aggregate model, and 2D-RAS(Two Dimensional Random Aggregates Software) was compiled. All the same kind of random triangle aggregate was generated randomly at one time, and then two dimensional aggregate of random shape was generated by the method of random extension.2. Numerical simulations were carried out with nonlinear finite element software Marc, which simulated the whole failure process of uniaxial tension specimen of three graded concrete of Dongjiang arch dam. The comparison between results of simulation of circle aggregate and that of polygon is studied to find out the effect of aggregate shape on mechanical performance and failure process of concrete.3. Six groups of random aggregate models of circle and polygon aggregate were generated by 2D-RAS, with the same content and ratio. Significant results were obtained from comparison of the simulation results.4. Aggregate location conflicting and overlapping criteria in the algorithm were established. Growth pattern and convexity conditions were analyzed for a convex polyhedron aggregate. The 3D-RAS (Three Dimensional Random Aggregate Software) was presented in the paper. The three dimensional generation of random aggregate model is based on two dimensional generation of random aggregate algorithm. Besides merits of the two dimensional generation of random aggregate model, It consider the effect of the radius of the different aggregates, which were assumed to obey normal distribution. Consequently, the numerical model generated is reasonable.5. The 3-D random model of convex polyhedron aggregate was generated with 3D-RAS. The mesh division is auto-performed by the method of projection, which projects finite element mesh onto the random aggregate model generated and assigns different material properties to the respective elements according to the element location in three phases. Numerical results show that the 3-D random aggregate model provides consistent results with these of 2-D.