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Identification of the Energy Absorption Characteristics of an Earthquake Resistant Structure: Description of the Identification Method.
McNiven, H. D.; Matzen, V. C.
National Science Foundation, Washington, DC. Applied Science and Research Applications., January 1976, 13 p.
The construction of a mathematical model of a single story steel frame, when subjected to earthquake inputs, using the system identification method, is the subject of this paper. The system identification method consists of three parts: the differential equation which reflects the physics of the system and which contains a set of parameters; the error function which reflects the difference in the structure's behavior and that predicted by the model; and the algorithm by which the parameter space is searched to find the set which minimizes the error function. The program for estimating the parameters was tested. It was first subjected to a numerical experiment using simulated data. The input is the acceleration time history of a recorded earthquake, but response data is generated by assigning values to each of the four parameters and obtaining the solution of the resulting equation. The program can be considered to be successful if the optimization algorithm, in a reasonable number of iterations, identifies the minimum point of the error function surface, as having the coordinates of the assigned values, when the search is begun at a variety of points in the remote terrain. The mathematical model was found to predict a response close to the physical response of the structure yet two major ways in which the estimation of the parameters could be improved are suggested.
Energy absorption; Earthquake resistant structures; Mathematical models; Earth movements; Dynamic response; Ground motion; Earthquake engineering; Differential equations; Nonlinear systems; Earthquakes