Basic Study on Damping Characteristics Evaluation of Concrete Structures Based on Impulse Excitation Tests

Abstract

This study focuses on the vibration tests of concrete materials to evaluate their dynamic characteristics including damping property. The vibration tests are conducted based on the impact excitation using an impulse hammer. The vibration response of an object is measured by a laser Doppler vibrometer. Frequency spectra are analyzed by a spectrum analyzer from the measured time history responses. This vibration test approach is applied to several specimens with different dimensions and water-cement ratios. Damping ratio of each mode for a specimen is calculated by half-width method with the measured frequency responses. The vibration test results confirmed that it is possible to extract differences in natural frequencies and damping ratios due to differences in the dimensions and water-cement ratios of the specimens. The measured natural frequencies were compared to those calculated by finite element analysis, resulting in good agreement between them. It is verified from the experiments that the present vibration test approach for the concrete materials can evaluate their dynamic properties and is effective to develop concrete structures with a desired damping in future.