Determination of modal properties of an irregular 20-story concrete shear wall building

Abstract

This paper presents the results obtained from the ambient vibration measurements done on a 20 story tall building, with reinforced concrete core, located in Vancouver, British Columbia, Canada. The experiment reveals the dynamic characteristics of the investigated building by advanced system identification methods using enhanced signal processing techniques and the fundamentals of frequency domain decomposition. The results include the natural frequencies and the mode shapes of the building obtained from the ambient vibration measurements. The dynamic characteristics of interest in this study are the lateral and torsional natural frequencies and the corresponding mode shapes. A total of 11 modes of vibration, up to the fourth translational and torsional modes, were successfully identified. This paper uses the Enhanced Frequency Domain Decomposition (EFDD) and the Curve-fit Frequency Domain Decomposition (CFDD) methods to identify the modes and utilizes the Frequency Domain Operating Deflection Shapes (FDODS) technique for modal validation. The experimental results were then compared to the analytical estimations from the ETABS models of the building created at the time of the structural design phase and model validation and calibration is performed.