NEHRP Clearinghouse
- Title
- Investigation of the Elastic Characteristics of a Three Story Steel Frame Using System Identification.
- File
- PB296225.pdf
- Author(s)
- Kaya, I.; McNiven, H. D.
- Source
- National Science Foundation, Washington, DC. Applied Science and Research Applications., November 1978, 117 p.
- Identifying Number(s)
- UCB/EERC-78/24
- Abstract
- In this report, three different models in increasing order of complexity have been used to identify the seismic behavior of a three story steel frame subjected to arbitrary forcing functions all of which excite responses within the elastic range. In the first model, five parameters have been used to identify the frame. Treating the system as a shear building, one stiffness coefficient is assigned to each floor and Rayleigh type damping is introduced with two additional parameters. The mass, assumed to be concentrated at a floor level, is kept constant throughout the study. The parameters are established using a modified Gauss-Newton algorithm. The match between measured and predicted quantities is satisfactory when these quantities are restricted to floor acceleration or displacement. To remove the constraint imposed by assuming the frame deforms as a shear building, a second model with eight parameters is introduced, allowing rotations of the joints as independent degrees of freedom. Six of the eight parameters are related to the stiffness characteristics of the structural members while the remaining two are related to damping as before. An integral squared error function is used to evaluate the discrepancy between the model's response and the structure's response when both are subjected to the same excitation. Different quantities such as displacements, accelerations, rotations, etc., are used in different combinations in forming the error function, in an effort to determine the best set of measurements that need to be made to identify the structure properly. The final eight parameter model is the last of three. The discoveries that were made between the first and third models are significant.
- Keywords
- Framed structures; Stiffness methods; Mathematical models; Dynamic response; Buildings; Earthquake engineering; Systems identification; Ground motion; Computer programming; Dynamic structural analysis