The main objective of this project is to develop a hybrid control system that requires almost no external energy to control the dynamic response of buildings and bridges during earthquakes and/or strong wind storms. This will be accomplished through two concurrent research activities. The first is directed toward the development of an active structural member which uses electro-rheological materials to control member stiffness and damping properties. The advantage of electro-rheological materials is that their mechanical properties can be changed by over a hundred- fold by a low amperage electrical field and that these changes can occur in milliseconds. Thus the development of active structural members whose dynamic properties can significantly change almost instantaneously on command provides a new opportunity for structural control. The second research task is to establish a new structural control approach which would utilize the unique properties of active structural members. This requires a new philosophy for development of control system algorithms, based on directly controlling variable structural properties. In addition to the research tasks described above the principal investigator will also undertake the technical coordination responsibility involving all projects awarded under the Structural Control Initiative NSF 91-62.
