Researchers involved with the CLC program wanted to test the feasability of verifying computer models of modal shaking in buildings on the UCSB campus. Program members, Francois Heuze (LLNL) and Ralph Archuleta (UCSB ICS) worked with personnel at Engineering 1 and Facilities Management to work out the details and actually make their wish a reality.
The shaker used belongs to UCSD (also involved with the CLC program) and was loaned to the project in mid-November. The 400 lb shaker is comprised of two semi-circular trays driven by a powerful DC-Brushless motor. The shaker produces horizontal forces along one axis by rotating the trays in opposite directions, cancelling out forces in one direction and focusing the forces in the other. The trays can each be loaded with up to twelve 30 lb lead plates. This means that the entire mechanism can weigh over 1/2 a ton fully loaded! The shaker was powered by a 5 Kw generator
On the evening of November 23, 1998, personnel from the Institute for Crustal Studies (ICS) at UCSB along with personnel from LLNL and UCSD deployed seismic recording equipment belonging to the Portable Broadband Instrument Center, managed by ICS, to record the shaking of the building. A total of seven 3 component seismic stations were deployed inside the building, mainly on the top three floors. Another five 3 component stations were deployed outside the building in a line oriented towards the permanent downhole station (USB) outside of the Geology Building (Webb Hall). A Schematic diagram of the deployment (GIF) or (PDF) shows the sensor locations.
At about 12:45 AM, the shaker was finally brought up to speed with about half of the plates loaded. Good records were recorded on all the seismic stations deployed and analysis is now underway.
A small sampling of the data was given to ECE professor Roy Smith who did some spectral analysis and put together some class notes for the students of his Signal Processing class.
Special thanks to all those people who either assisted directly in the project or who donated ideas or equipment to the project, but are not included in the text above or below. In particular: Joe Cisneros (UCSB Geology), Chuck Anderson (UCSB Geology), Art Sylvester (UCSB Geology), Ahmed Elgamal (UCSD) and Dale Clark (UCSB ECE).
Higher resolution verions of the pictures below are available by clicking on the images.
Deploying the seismic instrumentation in the early evening. Mike Watkins (UCSB/ICS) pictured.
Pictured above are several of the people involved in the shaking deployment. From left to right: Mike Watkins (UCSB/ICS), Viktor Shterental (UCSD), Francois Heuze (LLNL)
Viktor, Aaron Martin (UCSB/ICS) and Francois finishing the mounting of the shaker on the 5th floor of the Engineering 1 building.
Side view of the shaker. The trays containing the lead weights are inside the shaker. More of the lead plates are visible in the background against the rear wall. In the right foreground is a Force Balance Accelerometer (FBA) with improvised weighting to keep it from sliding around on the floor too easily. The FBA was used to monitor the motion near the shaker.
Top view of the shaker. The two trays containing lead weights are more visible int this photo. The direction of forces generated by the shaker are in the transverse axis (roughly the vertical axis of the picture). The FBA is also more visible in the top right portion of the picture.