The Damping Analysis of Experimental Concrete Beams under Free-Vibration

This paper presents an overview of the free-vibration damping analysis technique commonly employed by laboratories to determine the amount of material damping contained by a concrete specimen. From laboratory investigations the difficulties associated with a technique often employed for the extraction of damping from the free-vibration decay curve are identified. Extensive free-vibration tests undertaken on a wide variety of concrete beams indicate that for the traditional logdec technique, damping is to be extracted from the optimal peak ratio (An/A1) region of the free-vibration decay curve. An analysis of the effect of experimental test variables; hammer weight and hammer excitation position, on the calculation of damping is undertaken. The results show that neither test variable produces measurable impact on the calculation of damping.

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