Estimating The Stress Level Of Reinforced Concrete Beams Through The Acoustic Emission Parameter Distribution Analysis

Concrete is one of building materials applied most extensively in civil engineering,and therefore evaluating the stress level of concrete structures is of great significance in theory and in practice.Nowadays,few techniques are able to achieve that goal,while with weakness of inconvenience in implementing and limited effectiveness.This study investigated an innovative acoustic emission-based approach to qualitatively and quantitatively assess the stress level of a reinforced concrete(RC)beam cross section.Firstly,according to principles in Mechanics,a correlation between the stress diagram of an RC beam section and the corresponding acoustic emission(AE)distributing pattern was revealed.Secondly,responses of a typical balanced-reinforced beam were examined carefully.It was found that the stress level of the section can be estimated by utilizing two features(i.e.the degree of nonlinearity and the position of the peak)extracted from the stress diagram.Then,a mathematic model was established to characterize the features.Thirdly,thanks to the striking correlation discussed above,the features can also be extracted from the AE distributing pattern,and then the mathematic model was able to be adopted to fulfil the goal of estimating the stress level via AE measurements,yielding the AE-based stress level evaluating approach for a concrete beam cross section.Finally,data came from an experiment on six RC beam were employed to verify the correlation and the approach.Results showed that when specimens were in the elastic and working stages,the correlation was not very obvious due to low AE activity,and qualitative evaluation of the stress level via AE measurements was achievable;in failure stage of the specimens,the correlation was very strong in terms of quantitative aspect,and this enabled the precise determination of the stress level.Specifically,the two indictors of the approach matched with the variations in the stress exactly during the loading;in critical stages,the error of quantifying the stress level through the approach was about five percent.The work of this paper provides a new idea for the qualitative and quantitative analysis of structural behavior of Civil Engineering-structural response based on the correlation between the distribution of the stress distribution and the acoustic emission signal.