DETERMINATION OF THE ELASTIC MODULUS OF CONCRETE IN REINFORCED CONCRETE BEAMS BY THE RATE OF VIBRATION DAMPING

Abstract

The article shows a method for determining the modulus of elasticity of concrete by the measured dynamic characteristics of the tested structure – the damping coefficient of vibrations of reinforced concrete unstressed beams operating in the first stage of the stress-strain state. We have proposed to use this characteristic of reducing the amplitude of vibrations, which takes into account the loss of kinetic energy in a reinforced concrete beam. It is assumed that a change in the modulus of elasticity of concrete in the considered range will significantly affect the rate of damping of vibrations, since with an increase in the modulus of elasticity of concrete, the elastic properties of the reinforced concrete element prevail over the plastic properties. When conducting experiments, one should strive for the same support conditions and introduce an equal level of energy into the oscillatory system. In this case, the energy loss in the reinforced concrete beam, expressed by the value of the vibration damping coefficient, will allow to determine the modulus of elasticity of concrete with a higher degree of probability in comparison with the practiced mechanical or ultrasonic methods. We have developed a new method for determining the elastic modulus of concrete, based on the empirical determination of the vibration-damping coefficient of reference structures of a given type and size and the construction of a graphical dependence of the vibration damping coefficient on the elastic modulus of concrete. We have obtained greater accuracy in determining the modulus of elasticity of concrete in comparison with the practiced mechanical or ultrasonic methods.