Abstract
Wall buildings with vertically irregular configurations have been severely damaged or even collapsed due to the formation of a story mechanism during severe earthquakes, particularly under near-fault earthquake excitation. This paper presents a criterion to prevent such failures. A story-safety factor is defined to represent the relative reserve strength against a story mechanism in the structure. The validity of this factor was examined by conducting dynamic response analyses of various analytical models of 7- and 11-story wall structures with discontinuous wall panels in the first story using 29 real earthquake records (mostly near-fault records) and their scaled motions with various intensity levels. The results show that the proposed story-safety factor controlled well the failure mechanism of the structures. When the story-safety factor was larger than the corresponding dynamic shear magnification factor (Paulay and Priestley 1992) minus unity, a story mechanism did not occur in the structures in all cases. A practical procedure for using the story-safety factor to prevent the formation of a story mechanism in irregular stories is also presented.
