Effects on Impact-Echo Signals Caused by Steel Reinforcing Bars and Voids Around Bars

The paper explains the interaction of transient stress waves with steel bars in concrete and shows the effects that bars have on impact-echo signals. Numerical (finite element) and experimental results are shown to demonstrate the effects that different variables have on impact-echo results. Equations for the relationships between bar diameter, bar depth and the measured impact echo response are presented. It is shown that these relationships can be used to identify the effects caused by bars on impact-echo signals obtained from reinforced concrete structures. Finally, the changes in the impact echo response caused by the presence of a void around the top or bottom of a bar are also explained.