Application of Energy Balance Concept in Seismic Evaluation of Structures

The objective of this paper is to present a seismic evaluation procedure based on an energy balance concept. The method is based on a framework that utilizes energy demand and capacity diagrams. The skeleton force–displacement (capacity) curve of the structure is converted into an energy capacity plot that is superimposed over the corresponding energy demand plot for a given hazard level to determine the expected peak displacement demand. First, the energy balance concept as applied in the seismic design of structures is discussed. Next, the underlying theory and framework for carrying out seismic evaluation are presented. The analysis procedure is then applied to an example three-story moment frame structure to estimate the displacement demands. The results obtained from the proposed procedure are then evaluated and compared with the results from nonlinear dynamic analysis as well as those from other well-established nonlinear static procedures. Observations regarding the accuracy of different nonlinear static procedures are discussed. The results show that the proposed method can be used effectively to estimate the response under a given ground motion.