Abstract Database

INVESTIGATION AND ESTIMATION OF STORY STIFFNESS AND DAMPING RATIO OF A 4-STORY WOODEN STRUCTURE BY MICROTREMOR AND MASS SLIDING SHAKER

MEE07157
Sithipat Palanandana
Supervisor: Koichi MORITA
Country: Thailand
Abstractfulltext

In this study, the structural dynamic properties of a 4-story wooden structure were investigated. Microtremor observation was carried out to determine the first and second natural frequencies of the structure. Based on these preliminary results, mass sliding shaker was mounted on the structure to apply harmonic force vibration in order to excite the resonant behavior of the structure. Target frequencies were applied to the mass sliding shaker to obtain the responses for all four modal shapes. Signal obtained from the measurement was then mathematically converted from time domain to frequency domain using Fast Fourier Transform for better interpretation to determine all four natural frequencies. Based on these results, resonance curves for all four modal shapes were constructed. Curve fitting based on mathematical formula was also drawn by changing the values of damping ratio and peak amplitude to fit the resonance curve. From microtremor observation data and time history responses of free vibration, damping ratio of the structure was determined for comparison. Based on curve fitting of resonance curves, natural frequencies and participation functions were also identified. Using story mass in addition to these identified properties, stiffness matrix could be determined. Finally, each story’s stiffness was obtained by multiplying stiffness matrix by unit displacement vector.

Citation: Bulletin of IISEE, 43, 109-114.