- Author
- Phan, L. T.
- Title
- Seismic Instrumentation of Existing Buildings.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Sponsor
- General Services Administration, Washington, DC
- Report
- NISTIR 4419, October 1990, 62 p.
- Distribution
- Available from National Technical Information Service
- Keywords
- analytical model | buildings | dynamic | earthquakes | frequency | ground acceleration | instrumentation | model | mode shape | seismometers | spectral density | vibration
- Abstract
- Two existing GSA buildings, one in Long Beach, California and one in Portland, Oregon, were subjected to low-level vibration tests to determine their dynamic properties and response frequencies. The measured dynamic properties of the buildings were incorporated into the computer models of the buildings and time-history analyses using these models were performed. Reasonable agreement between the measured and calculated response frequencies and deflected shapes were observed. The differences in calculated and measured response frequencies range from 3% to 31%. The larger difference is in the torsional response of the Portland building. This is probably due to the irregular geometry of this building. The models were then analyzed with past earthquake acceleration records used as source of excitations. The Portland building was subjected to three components of acceleration obtained from the November 1962 Portland earthquake. The Long Beach building was subjected to three components of acceleration obtained from the 1987-Whittier Narrows earthquake. The purpose of the analyses is to reveal building response under these realistic earthquake excitations, so that logical seismic instrumentation schemes can be developed for these buildings. The results of the analyses suggest that the response of the Portland building is influenced more by torsional and rocking motions, while the response of the Long Beach building is influenced mainly by translational modes. From the observed behavior of the buildings, a seismic instrumentation scheme is developed for each building, and a general guideline for seismic instrumentation in existing building is recommended.