Graphic dynamic earthquake response analysis of one-way asymmetric systems

Abstract

Two graphic dynamic methods of earthquake response analysis are developed for elastic one-way asymmetric torsionally coupled systems (2DOF) subjected to unidirectional earthquake forces. The methods are referred to as Graphic Response History Analysis (GRHA) and Graphic Response Spectrum Analysis (GRSA). Based on the results from the Graphic Modal Analysis (Faggella 2013) the GRHA and the GRSA use the centers of rotation of the mode shapes (the "nodes"), the lines of action of the modal forces, and the modal frequencies to determine graphically the modal participating factors and mass ratios, the modal expansion of earthquake loads, and the modal responses. In the GRSA the maximum modal responses are then combined using a graphic adaptation of the SRSS and CCQ combination rules based on the elastic response spectrum. The methods allow a fully graphic computational visualization of the earthquake response and of key parameters governing the dynamic behavior, in support of the design and analysis of torsionally coupled structures.