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System Identification of Structures with Joint Rotation.
Dimsdale, J. S.
National Science Foundation, Washington, DC., July 1983, 111 p.
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The goal of this research is to investigate the role of joint behavior in the identification of frame models from dynamic response data caused by seismic forcing functions. An optical method has been devised for accurately measuring joint rotation of a structure during earthquake excitation. This method has been applied to a simple six story frame in which the columns have approximately the same stiffness as the girders. Response data have been collected for a variety of base motion histories. Also studied are data previously collected from a three story frame in which joint rotation information has been inferred from strain measurements. A number of different mathematical models of these structures are evaluated using system identification. Each mathematical model depends on a number of parameters related to the characteristics of the structure. An iterative method is applied to calculate the values of these parameters which best reproduce the measured response of the structure. The form of the mathematical model has an effect on the degree to which the optimal parameters accurately reflect physical properties of the structure, and also influences the set of response quantities necessary for calculating an optimal set of parameters.
Seismic waves; Mechanical hystereses; Earthquake engineering; Loads (Forces); Joints (Junctions); Rotation; Excitation; System identification; Strain measurements; Mathematical models; Cyclic loads; Framed structures; Dynamic structural analysis