Evaluation of Vibrations in Simple Structures Using the Laser Photo Deflection Method (LDP): Part 2

The objective of this research is to continue with the results of the first part of our project, the evaluation of vibrations in simple structures using the laser photodeflection method (LPD): in part 2 we present the results of the evaluation of vibrations of a pure concrete column. As stated in a previous report (part 1), the method that was applied is again a combined optoacoustic (non-destructive) procedure, whereby the vibration of the structure is induced by sound and vibrations are detected optically. The reflected laser beam deflects around the sensor in tune with the produced vibration (LPD). Experimentally, the first 12 resonant frequencies are obtained and the results are discussed within the framework of the known basic theoretical approaches. As initially indicated, the column has a length L = 1.75 m from the ground (earth), however, the column in turn has an embedment in the ground of about 30 cm, so the total effective length of the column is 2.05 m, which would significantly modify the evaluation of E to almost 11 GPa.