Experimental Method for Structural Concrete Damping Properties Evaluation

This article proposes a solution for structural materials such as concrete and cement mortars dynamic properties investigation using experimental modal analysis technique. The studied dynamic characteristics of structural materials include the dynamic modulus of elasticity and the loss factor or its derivatives: the logarithmic oscillation decrement or the relative damping coefficient. Closed expressions are presented for determining the loss factor of mechanical vibrations, obtained on the basis of solving the differential equation for vibrations of a single-mass dynamic system. A method for calculating the loss factor based on the analysis of the spectrum of the transfer function of an oscillatory system loaded with an impulsive dynamic force is presented, in which the results of measuring accelerations at various points of the sample are used as a response. The experiments were carried out on short and long samples made from samples of structural materials - cement mortars with a density of 1500 - 1900 kg/m³ with special aggregates. Based on the solution of the equation of oscillations of a beam with distributed masses, a formula is presented for determining the dynamic modulus of elasticity of the beam material.