Ambient vibration testing of a 4-storey parking garage

Abstract

This paper presents the results of ambient vibration tests performed on the 4-storey reinforced concrete Health Sciences Parkade at the University of British Columbia in Vancouver, Canada. Two tests were conducted in March 2014 under different operational conditions: for the first test, a detailed ambient vibration test, was conducted during normal operating conditions while in the second test, the data was acquired when the Parkade was almost empty, but only at a few locations. The comparison between the results of the two tests shows that the frequency values are quite similar, even if the levels of vibration during the first test were much higher than those from the almost empty case. The vertical component of vibration was found to be predominant motion, showing a strong amplification of the vibrations due to traffic. The results also show that the “added” mass due to the presence of the cars did not significantly affect the modal frequencies. The Frequency Domain Decomposition (FDD) and the Stochastic Subspace Identification (SSI) were used to estimate the dynamic parameters of the structure. A total of six modes were identified within the frequency range of 2-8 Hz, and all showed a significant 3D response. The natural frequencies and mode shapes from each technique have been compared and the similarities and differences are further discussed in the paper.