CALCULATION OF FIBER-REINFORCED CONCRETE STRUCTURES TAKING INTO ACCOUNT PHYSICAL NONLINEARITY

Abstract

The availability of information about the physical and mechanical properties of fiber-reinforced concrete allows to calculate structures based on it with a proper approximation to reality. The experimental data on the elastic modulus of the first and second kind, the Poisson's ratio, the tensile and compressive strength limits for characteristic fiber lengths and the percentage of reinforcement by weight are a condition for creating an algorithm for calculating such structures. This is facilitated by the transition from a linear elastic formulation of the problem to the consideration of physical nonlinearity. In the framework of software systems based on a finite element model of a deformable body, an iterative process is acceptable, due to the convergence of the solution. The proposed method of additional loads in the finite element interpretation leaves the accumulated experience of computer-aided design. The iterative calculation procedure contains cycles with a gradual approximation of the physical modules to their true value as a result of the convergence of the solution of the problem. The convergence criterion has an energy nature. The calculation of the modules is based on the dependencies of the mechanics of a deformable solid. This gives a fundamental character to the formulation of the problem. The effect of the proposed method is demonstrated by the example of calculating a buried cylindrical tank made of glass-fiber concrete for liquid. The addition of glass fibers to concrete leads to an improvement in the resistance to cracking and a decrease in the amount of crack opening.