NEHRP Clearinghouse
- Title
- Simple Models for Computing Dynamic Responses of Complex Frame Structures.
- File
- PB292798.pdf
- Author(s)
- Chen, C. C.; Sun, C. T.; Bogdanoff, J. L.; Lo, H.
- Source
- National Science Foundation, Washington, DC. Applied Science and Research Applications., April 1978, 96 p.
- Abstract
- Prohibitive costs of analyzing large frame structures using the finite element method have led researchers to investigate simpler procedures of analysis. The development of a simple shear beam and a Timoshenko base model for dynamic analysis of complex frame structures is described. Formulas are derived for computing the equivalent shear and bending rigidities of the structure. Simple models are evaluated by comparing simple model solutions with solutions obtained from using full scale finite elements in free vibrations of plane frames. It was found that the simple models yield very accurate frequencies as well as mode shapes for the lower modes, and the Timoshenko model is more superior to the shear beam model when diagonal bracings are present. When the shear beam model was employed to compute the natural frequencies of a TVA fossil fuel power plant at Paradise, Kentucky, the first two frequencies were found to be in good agreement with the finite element solutions. The simple models were also used to compute transient dynamic responses of structures subjected to earthquake disturbances. Evaluative examples and dynamic internal force and moment computations using simple models are included.
- Keywords
- Earthquake resistant structures; Framed structures; Vibration; Timoshenko beam; Earth movements; Shear properties; Electric power plants; Ground motion; Earthquake engineering; Kentucky; Resonant frequency; Paradise (Kentucky); Earthquakes; Dynamic structural analysis