Active Control Experiments and Structural Testing
As in all other new technological innovations, experimental verification constitutes a crucial element in the maturing process as active structural control progresses from conceptualization to actual implementation. Experimental studies are particularly i
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ACTIVE CONTROL EXPERIMENTS AND STRUCTURAL TESTING
T.T. Soong State University of New York at Buffalo, Buffalo, NY, USA
ABSTRACT As in all other new technological innovations, experimental verification constitutes a crucial element in the maturing process as active structural control progresses from conceptualization to actual implementation. Experimental studies are particularly important in this area since hardware requirements for the fabrication of a feasible active control system for structural applications are in many ways unique. As an example, control of civil engineering structures requires the ability on the part of the control device to generate large control forces with high velocities and fast reaction times. Experimentation on various designs of possible control devices is thus necessary to assess the implementability of theoretical results in the laboratory and in the field. In order to perform feasibility studies and to carry out control experiments, investigations on active control have focused on several control mechanisms as described below.
ACTIVE BRACING SYSTEM {ABS) Active control using structural braces and tendons has been one of the most studied mechanisms. Systems of this type generally consist of a set of prestressed
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
tendons or braces connected to a structure whose tensions are controlled by electrohydraulic servomechanisms. One of the reasons for favoring such a control mechanism has to do with the fact that tendons and braces are already existing members of many structures. Thus, active bracing control can make use of existing structural members and thus minimize extensive additions or modifications of an as-built structure. This is attractive, for example, in the case of retrofitting or strengthening an existing structure. Active tendon control has been studied analytically in connection with control of slender structures, tall buildings, bridges and offshore structures. Early experiments involving the use of tendons were performed on a series of small-scale structural models (Roorda, 1980), which included a simple cantilever beam, a king-post truss and a free-standing column while control devices varied from tendon control with manual operation to tendon control with servovalve-controlled actuators. More recently, a comprehensive experimental study was designed and carried out in order to study the feasibility of active bracing control using a series of carefully calibrated structural models. As Fig. 1 shows, the model structures increased in weight and complexity as the experiments progressed from Stage 1 to Stage 3 so that more control features could be incorporated into the experiments. Figure 2 shows a schematic diagram of the model structure studied during the first two stages. It is a three-story steel frame modeling a shear building by the method of mass simulation. At Stage 1, the top two fl.oors were rigidly braced to simulate a sin
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