Active Control Development in the U.S. and Case Studies
As we have seen, full-scale implementation of active control devices in buildings has taken place, but all installations in either full-scale test structures or new buildings can only be found in Japan. However, some of the operational full-scale active s
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ACTIVE CONTROL DEVELOPMENT IN THE U.S. AND CASE STUDIES
T.T. Soong State University of New York at Buffalo, Buffalo, NY, USA
ABSTRACT As we have seen, full-scale implementation of active control devices in buildings has taken place, but all installations in either full-scale test structures or new buildings can only be found in Japan. However, some of the operational full-scale active systems are the result of US-Japan research collaborations and U.S. researchers were responsible for the design, fabrication and installation of an active bracing system in a full-scale dedicated test structure for structural response control under seismic loads (Soong et al., 1991; Reinhorn et al., 1992; Reinhorn et al., 1993). In addition, at least two designs have been completed for the purpose of retrofitting existing deficient structures in the U.S. The active bracing system and one of the design projects are briefly described below.
FULL-SCALE ACTIVE BRACING SYSTEM In 1990, a full-scale active bracing system (ABS) was designed and fabricated by U.S. researchers and installed in a dedicated test structure in Tokyo for performance verification of the system under actual seismic ground motions. As shown in Fig. 1, the structure is a symmetric two-bay six-story building constructed of rigidly connected steel frames of rectangular tube columns and W-shaped beams with reinforced concrete slabs at each of the floors. Weighing 600 metric tons, the
T. T. Soong et al. (eds.), Passive and Active Structural Vibration Control in Civil Engineering © Springer-Verlag Wien 1994
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T.T. Soong
structure was designed as a relatively flexible structure with a fundamental period of 1.1 sec in the strong direction and 1.5 sec in the weak direction, in order to simulate a typical high-rise building. The structure has low damping in the dominant modes (between 0.5% and 1% of critical). The ABS consists of solid diagonal tube braces attached to the first story of the building as shown in Fig. 1. The control system enables longitudinal expansion and contraction of the braces by means of hydraulic servocontrolled actuators attached along the braces. The control system includes also a hydraulic power supply, an analog and digital controller, and analog sensors as shown schematically in Fig. 2.
(a) Top View
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Fig. 1 Full-Scale Structure with ABS
Active Control Development in the U.S.
Fig. 2
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Block Diagram of ABS
Since velocity sensors are available at the first, third, and sixth floors, a simplified control law was formulated using direct three-velocity feedback. Elaborate fail-safe measures were incorporated into the control software and hardware. Besides the normal operating routines , the control program contains several routines for testing and verifying integrity of the system . When a problem is detected anywhere in the system hardware or software, the control program will determine if the error is critical or not . If the error can be identified
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