Akademik Veri Yönetim Sistemi
7th International Operational Modal Analysis Conference, Ingolstadt, Almanya, 9 - 12 Mayıs 2017, ss.238-241
This paper presents a sequence of forced and ambient vibration tests performed on a six-story precast concrete building prior to any non-structural elements in place. The building is 20.2 m tall and 53.2 m by 15.8 m in plan. In forced vibration testing, the building is excited along its short and long axes, respectively, by a fifth-floor level vibration generator with a known sinusoidal force. Sweeping the vibration generator frequency from 0.5 to 9.5 Hz, structural vibrations are recorded by a dense network of 22 uniaxial accelerometers deployed throughout the building. Upon signal processing of the records with the use of the analytical signal, an application of the Hilbert transform, acceleration and displacement-frequency response curves are determined. In ambient vibration testing, the building is presumably excited by a white noise random process. Ambient vibrations are recorded for at least 30 minutes following each forced vibration test setup with the same configuration of accelerometers. Structural system dynamic properties are then identified using well-established straightforward methods in the structural dynamics area from forced vibration testing and using frequency domain decomposition methods from ambient vibration testing. Natural vibration frequencies, modal damping capacities, and vibration mode shapes are subsequently compared. These comparisons justify the use of ambient vibration records in lieu of the forced vibration test of the building.