UTHM Conference Portal, 4th International Conference on Civil and Environmental Engineering for Sustainability (IConCEES 2017)

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Structural health monitoring on medium rise reinforced concrete building using ambient vibration method
Ahmad Fahmy Kamarudin, Shahrul Niza Mokhatar, Mohd Hazreek Zainal Abidin, Mohd Effendi Daud, Muhammad Shafiq Rosli, Azmi Ibrahim, Zainah Ibrahim, Mohammad Soffi Md Noh

Last modified: 2017-11-25


Monitoring of structural health from initial stage of building construction to its serviceability is an ideal practise to assess structural defect or damage. A structural vulnerabilities might be subjected to natural or artificial effects such as aging, excessive loading or forces, faulty structural design and unsuitable configurations, unsatisfactory construction materials, failure of ground-structure interaction etc. The structural integrity could be intruded by any types of these deterioration and destruction activities, and worse if without remedy action of monitoring, building re-assessment or maintenance is taken. In this study the application of ambient vibration (AV) testing is utilized to evaluate the health of eighth stories medium rise reinforced concrete building in Universiti Tun Hussein Onn Malaysia (UTHM), based comparison made between the predominant frequency, fo, determined in year 2012 and 2017. For determination of fo, a popular method of Fourier Amplitude Spectra (FAS) was used to transform the ambient vibration time series which were recorded by 1 Hz tri-axial seismometer sensors and CitySharkII data recorder. From analysis of the peaks FAS curves, the first mode frequencies indicate at 2.04 Hz in 2012 and 1.97 Hz in 2017 with 3.14% of frequency reduction after five years interval, but in steady state frequencies shown for the second and third modes of frequencies which are 2.42 Hz and 3.31 Hz in both years.  Two translation mode shapes were found at the first and second mode frequencies in the North-South (NS-parallel to building transverse axis) and East-West (EsW-parallel to building longitudinal axis) components, while the torsional mode shape shown at the third mode frequency in both years. No excessive deformation amplitude was found at any selective floors based on comparison made between three mode shapes produced, that could bring to potential feature of structural deterioration. Finally, the low percentages of natural frequency disparity within five years of duration interval shown by the first mode frequencies under ambient vibration technique was considered in good health state, according to previous researchers recommendation which acceptable below 5 to 10%  over the years.