Dense Instrumentation of Federal Buildings in the San Francisco Bay Region

The historical Court of Appeals Building in San Francisco, California (Photo 1) has been recently  retrofitted by a base-isolation system. During the retrofit, the U.S. Geological Survey with the cooperation of the U.S. General Services Administration installed a total of 36 channels of accelerometers with state-of-the-art digital recording capability (operational as of 1998). During future earthquakes, the dense array of recorders will provide vital data on the performance of the isolators and the response of the superstructure. A free-field station has been deployed close to the building which will provide key input data for evaluation of structures in the proximity of the Court of Appeals Building and will contribute to the assessment of the variation of ground motion within downtown San Francisco.

        Court of Appeals Building in San Francisco

The second building that is cooperatively instrumented is the three-story (two plus basement) McKelvey Building on the USGS Western Regional Campus in Menlo Park, California (Photo 2). The construction of this building had started when the 1994 Northridge earthquake occurred causing damages to column-beam joints of many steel buildings. The design engineers for the McKelvey Building revised the steel connections during the construction process. The 11-channel array of recorders in the building is designed to provide translational, torsional and pounding response information of the building using digital recording capability. Also, within close proximity, is a free-field station that will provide important information related to the variation of motions within the vicinity of the USGS campus.

McKelvey Building, USGS Menlo Park Campus