Analysis of Elastic Wave Parameters in the Elements of the "Striker – Gasket – Reinforced Concrete Beam" System

Abstract

Application of automated monitoring systems ensures the deformation safety of structures. Such deformation control systems are supplemented with the tools, which allow evaluation of the criticality of the structure state on the basis of vibration measurements. These are acoustic emission registration systems and shock wave diagnostics systems.The results obtained in this study are directly related to the shock-wave vibrodiagnostics of reinforced concrete structures. Particular attention is given to vibrodiagnostics in a "spare mode", which causes no inelastic deformation to appear in the elements of the examined structure.The objective of this work is to find local impact parameters for excitation of mechanical oscillations of a desired spectrum in the structure and to excite an elastic wave with required wavefront characteristics. One of the main impact parameters determining these characteristics is the pulse duration. Based on the results of the numerical experiment performed on the basis of a mathematical model of dynamic elastic interaction of the elements of the "striker – gasket – reinforced concrete beam" system, the duration of the impulse action on the beam was determined depending on various factors. Thus, within a specified range of these factors the greatest interval of impulse duration is obtained under variation of the striker velocity within the interval from 0.1 ms to 3 ms. Assuming that the impulse duration defines one of the main wave frequencies of vibrations one may conclude that frequencies will vary in the range from 300Hz to 10000Hz.