Collapse-Inducing Ground Motions

In this chapter, the weakest ground motions that can collapse the 3-story steel SMF and 20-story steel EBF buildings are determined. Because energy demand (ED) is proposed as a measure of the strength of ground shaking, the weakest ground motions are those with the lowest energy demand. Deformability and hysteretic damping are highly important in collapse prevention, but in prescriptive seismic design, deformability and hysteretic damping are not explicitly considered. Their effect is considered by applying judgment-based load reduction factors. This makes the prescriptive seismic design quite arbitrary. In collapse prevention, deformability and hysteresis are as important as strength; hence, they should be explicitly considered in seismic design. The most important seismic characteristic of a building is the minimum ED needed to collapse that building.