NEHRP Clearinghouse
- Title
- Data Analyses for Safety Evaluation of Existing Structures.
- File
- PB81186074.pdf
- Author(s)
- Chen, S. J. H.; Yao, J. T. P.
- Source
- National Science Foundation, Washington, DC. Office of Planning and Resources Management., December 1980, 100 p.
- Identifying Number(s)
- CE-STR-80-18
- Abstract
- The state of structural safety is evaluated by using rational indicators which are related to the physical deterioration of existing structures. Two such indicators--natural fundamental frequency, and damping ratio are studied. An approach for safety evaluation of existing structures utilizing system identification techniques is emphasized. Specifically, changes of estimated parameters such as natural frequencies and damping ratios during an earthquake are correlated with the observed structural damage. The application of simple methods of system identification to existing structures from observations of responses to earthquake inputs is elucidated. Numerical examples of two existing buildings and two test structural models with various damage levels are given to demonstrate the effectiveness of these new methods. The significance of changes in structural characteristics with respect to time is discussed. Results which are improved by imposing various conditions to remove undesirable data points and the treatment of measurement noise and error are presented. Available data are summarized and plotted to show the relationship between damage ratio and change in natural frequency of structures. Recommendations are made for the further improvement of this approach.
- Keywords
- Structures; Seismic design; Damage assessment; Seismic waves; Dynamic response; Earthquake engineering; Resonant frequency; Computer programs; Earthquakes; Dynamic structural analysis