Evolution of Dynamic Properties of a 5-Story RC Building During Construction

Abstract

A full scale five-story reinforced concrete building was built and tested on the NEES-UCSD shake table. The purpose of this experimental program was to study the response of the structure and nonstructural systems and components (NCSs) and their dynamic interaction during seismic excitation of different intensities. The building specimen was tested under base-isolated and fixed-based conditions. Furthermore, as the structure was being built, an accelerometer array was deployed in the specimen to study the evolution of its modal parameters during the construction process and due to placement of major NCSs. A sequence of dynamic tests, including daily ambient vibration tests, impact/free vibration and forced vibration (white noise base excitation) tests, were performed on the structure at different stages of construction. Several state-of-the-art system identification methods, including two output-only (SSI-DATA and NExT-ERA) and one input-output (OKID-ERA), were used to estimate the modal properties of the structure (natural frequencies, damping ratios and mode shapes). The results obtained allow to compare the modal parameters obtained from different methods as well as the performance of these methods and to investigate the effects of the construction process and NCSs on the dynamic properties of the building specimen.