16 Effects of Seismic Retrofit on the Dynamic Properties of a 4-Storey Parking Garage 129 Table 16.1 Summary of the results of the ambient vibration test of March 2015 Frequency [Hz] Damping [%] Mode FDD EFDD SSI-PC EFDD SSI-PC Comment Site period 0.641 0.651 – 3.52 – Site period 1 3.047 3.064 3.059 3.24 3.272 1st N–S longitudinal 2 3.822 3.904 3.897 2.37 3.617 1st torsional 3 4.578 4.48 4.36 1.48 5.502 1st torsional C1st E–W transversal 4 5.941 5.914 5.949 1.08 2.395 2nd torsional 5 7.069 7.09 7.184 0.24 3.438 2nd N–S longitudinal antisymmetric 6 8.344 8.318 8.499 0.40 2.671 3rd N–S longitudinal symmetric Table 16.2 Comparison of the results before and after the seismic upgrade Mode 2014 FDD results 2015 FDD results Difference [Hz] Difference [%] 1 2.756 3.047 0.291 10.56% 2 3.875 3.822 0.053 1.37% 3 4.413 4.578 0.165 3.74% 4 5.781 5.941 0.16 2.77% 5 7.25 7.069 0.181 2.50% 6 7.931 8.344 0.413 5.21% Acknowledgements The authors would like to acknowledge the technical and financial support of the Earthquake Engineering Research Facility (EERF) at the University of British Columbia, in Vancouver. The authors wish to acknowledge Amir Deris, Jesper Pedersen, Louis Moskven and Matthew Liman, graduate students at UBC, for their help during the Ambient Vibration Test and the data acquisition process. The help of Dr. Tim White is greatly appreciated, for providing the authors with information about the seismic upgrade interventions on the Parkade. The authors would like to thank Mr. André Harrmann, Associate Project Manager of Infrastructure Development, Project Services at UBC for providing access and information about the Parkade. Finally, the authors would like to thank Dr. Palle Andersen of Structural Vibration Solutions A/S for providing a special license of ARTeMIS Modal. References 1. MoHo s.r.l.: MOHO Sience and Technology. Venice 2. Structural Vibration Solutions A/S: Artemis. Software for Operational Modal Analysis. Aalborg 3. Capraro, I., Pan, Y., Rollins, K., Gao, W., Ventura, C.E.: Ambient vibration testing of a 4-storey parking garage. In: IMAC XXXIII, Orlando (2015) 4. Capraro, I., Ventura, C.E.: Model updating of a 4-storey parking garage using ambient vibration measurements. In: 11th Canadian Conference on Earthquake Engineering, Victoria (2015)
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