EFFECTS OF POISSONS-RATIO ON IMPACT-ECHO TEST ANALYSIS

Although the Poisson's ratio of concrete is known to vary within a sig nificant range of values, the resulting effects on impact-echo test re sults have not been studied. In this regard, background to the problem is given followed by an introduction to the impact-echo test techniqu e. An exact analysis model for impact-echo data, guided-wave analysis (GWA), based on elastic guided wave-propagation theory is introduced a nd experimentally demonstrated to be a powerful alternative to the exi sting impact-echo analysis model (IEM). It is shown that the IEM model cannot account for changing values of the material Poisson's ratio, w hereas the new GWA model can. Relationships among the Poisson's ratio, shear-wave velocity, and longitudinal-wave velocity of a material and the associated impact-echo test results are developed through the use of the GWA model. This development involves a parametric investigatio n of predicted impact-echo test results for solid- and hollow-rod stru ctures. The significant effect of Poisson's ratio as well as longitudi nal- and shear-wave velocity on such impact-echo results is demonstrat ed, and directions for future work are suggested. Conclusions concerni ng the validity of the GWA and IEM models and the significance of IEM analysis errors, owing to the disregard of Poisson's ratio as a signif icant factor, are given.