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Identification of natural frequency of low rise building on soft ground profile using ambient vibration method

Kamarudin, A. F. and Zainal Abidin, M. H. and Mokhatar, S. N. and Daud, M. E. and Ibrahim, A. and Ibrahim, Z. and Md Noh, M. S. (2017) Identification of natural frequency of low rise building on soft ground profile using ambient vibration method. In: International Seminar on Mathematics and Physics in Sciences and Technology 2017 (ISMAP 2017), 28–29 October 2017, Hotel Katerina, Malaysia.

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Abstract

Natural frequency is the rate at which a body to vibrate or oscillate. Application of ambient vibration (AV) excitation is widely used nowadays as the input motion for building predominant frequency, fo, and ground fundamental frequency, Fo, prediction due to simple, fast, non-destructive, simple handling operation and reliable result. However, it must be emphasized and caution to isolate these frequencies (fo and Fo) from spurious frequencies of site-structure effects especially to low rise building on soft ground deposit. In this study, identification of fo and Fo by using AV measurements were performed on ground and 4-storey primary school reinforced concrete (RC) building at Sekolah Kebangsaan (SK) Sg. Tongkang, Rengit, Johor using 1 Hz of tri-axial seismometer sensor. Overlapping spectra between Fourier Amplitude Spectra (FAS) from and Horizontal to Vertical Spectra Ratio (HVSR) were used to distinguish respective frequencies of building and ground natural frequencies. Three dominant frequencies were identified from the FAS curves at 1.91 Hz, 1.98 Hz and 2.79 Hz in longitudinal (East West-EW), transverse (North South-NS) and vertical (UD) directions. It is expected the building has deformed in translational mode based on the first peak frequency by respective NS and EW components of FAS spectrum. Vertical frequency identified from the horizontal spectrums, might induces to the potential of rocking effect experienced by the school building. Meanwhile, single peak HVSR spectrum at low ground fundamental frequency concentrated at 0.93 Hz indicates to the existence deep contrast of soft deposit. Strong interaction between ground and building at similar frequency (0.93 Hz) observed from the FAS curves on the highest floor has shown the building to behave as a dependent unit against ground response as one rigid mass.

Item Type: Conference or Workshop Item (Paper)
Subjects: T Technology > TH Building construction > TH845-895 Architectural engineering. Structural engineering of buildings
Divisions: Faculty of Civil and Environmental Engineering > Department of Structural and Material Engineering
Depositing User: Mr. Mohammad Shaifulrip Ithnin
Date Deposited: 31 Jul 2019 01:00
Last Modified: 31 Jul 2019 01:00
URI: http://eprints.uthm.edu.my/id/eprint/11402
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