WenXin Qin and ZhenFang Yuan
In this paper the Liapunov stability of motion theory is introduced to the structural dynamic analysis. The analytic procedure of stability for nonlinear seismic analysis is presented. The criterion of stability is established for the seismic analysis of SDOF system. Based on the method of normal coordinate transformation and the criterion of stability of SDOF system, the criterion of stability is established for the MDOF system subjected to earthquake ground motion. A simple and effective criterion of stability is also established for the shear model adopted in dynamic analysis of buildings. The relation between the seismic collapse and the stability of motion for buildings is discussed. The collapse definition of buildings subjected to earthquake ground motion is defined. Finally, the collapse response of a fifteen story reinforced concrete block masonry building subjected to EI Centro earthquake ground motion is analyzed. The beginning collapsing time of the building is determined by the collapse definition presented.