Approximate floor acceleration demands in multistory buildings. II: Applications

The accuracy of an approximate method to estimate floor acceleration demands in multistory buildings responding elastically or practically elastic when subjected to earthquake ground motion is investigated. Modal analysis is used in combination with approximate dynamic characteristics computed using a simplified continuous model that is fully defined with only four parameters. The accuracy of the method is first evaluated by comparing the response computed with the approximate method to that computed with response history analyses of complete finite element models of two generic buildings available in the literature. A comparison of exact and approximate dynamic characteristics is presented. Approximate peak floor acceleration demands and its variation along the height of the buildings are compared to exact demands when the buildings are subjected to an ensemble of 20 ground motions. The accuracy of the method is then evaluated by comparing floor acceleration demands computed with the approximate method to those recorded in four instrumented buildings in California. Results show that the approximate method produces good results with a very small computational effort.