The Earthquake Engineering Online Archive

System identification of structures with joint rotation

Dimsdale, Jerry S.

UCB/EERC-83/16, Earthquake Engineering Research Center, University of California, Berkeley, 1983-07, 99 pages (555.3/D55/1983)

This paper describes research on the role of joint behavior in the identification of frame models, based on data on dynamic response caused by seismic forcing functions. An optical method devised for accurately measuring joint rotation of a structure during earthquake excitation 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 for 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 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. Findings are discussed, including the effect of the mathematical model on the degree to which the optimal parameters accurately reflect physical properties of the structure. Also discussed is the influence of the form of the model not only on the number of parameters and degrees-of-freedom, but also on the set of response quantities necessary for calculating an optimal set of parameters.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-83-16.pdf (4 MB)