<title>Vibration control and isolation design for the Electrical Engineering/Computer Science Building, University of Minnesota--Minneapolis, Minnesota</title>

Abstract

Design of the Electrical Engineering/Computer Science Building at the University of Minnesota included development of a very low vibration environment for research in submicron processes in microelectronics. The new facility which opened in 1988 has 325,000 gross square feet of space on six floors and cost approximately $DLR35 million. The vibration control process consisted of: (1) establishing permissible vibration levels for extremely sensitive equipment, (2) monitoring site vibration, (3) isolating the microelectronics lab, (4) analyzing expected floor motion in the structure using finite element methods, and (5) isolating the HVAC mechanical equipment. The permissible floor vibration for the facility was 100 (mu) in/sec for the microelectronics floor and 1,000 (mu) in/sec for the remainder of the facility. Since there were several large engineering buildings and a main vehicular thoroughfare directly adjacent, vibration measurements taken at the site during the design phase showed the maximum ground surface and floor motion to be 1,350 (mu) in/sec and motion in the bedrock level at only 40 (mu) in/sec. A two-foot thick, solid, reinforced concrete floor was designed for the microelectronics lab, supported on three-foot diameter caissons down to bedrock, spaced on nine-foot centers and isolated from the soil. A computerized structural vibration analysis was completed with a finite element model of a typical bay of the entire building to predict response of the building to ambient and equipment excitation. The results of these predictions along with the building performance test data show the floor motion to be less than permissible levels.