Evolution of Dynamic Properties of a 5-Story RC Building During Construction
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.
KeywordsSystem identification Full-scale specimen Shake table tests Non-structural components Construction process
This project was a collaboration between four academic institutions: The University of California at San Diego, San Diego State University, Howard University, and Worcester Polytechnic Institute, four major funding sources: The National Science Foundation, Englekirk Advisory Board, Charles Pankow Foundation and the California Seismic Safety Commission, and over 40 industry partners. Additional details may be found at bncs.ucsd.edu. Through the NSF-NEESR program, a portion of funding was provided by grant number CMMI-0936505 with Dr. Joy Pauschke as program manager. The above support is gratefully acknowledged. Support of graduate students Consuelo Aranda, Michelle Chen, Elias Espino, Steve Mintz, Elide Pantoli and Xiang Wang, the NEES@UCSD and NEES@UCLA staff, and consulting contributions of Robert Bachman, Chair of the project’s Engineering Regulatory Committee, are greatly appreciated. Design of the test building was led by Englekirk Structural Engineers, and the efforts of Dr. Robert Englekirk and Mahmoud Faghihi are greatly appreciated in this regard. Opinions and findings in this study are those of the authors and do not necessarily reflect the views of the sponsors.
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