Seismic and Cyclonic Response of Continuous Frames

Damage to continuous framing caused by the lateral forces resulting from seismic tremors or cyclonic winds can be catastrophically severe. Cross sections forced early into plastic hinging may enter a failing stage prior to the development of ductile properties of remaining sections, or the formation of a collapse mechanism may occur with uncontrolled increases in strain at hinging sections. Analog computer studies are presented which lead to the conclusion that increases in strains should be accompanied by stress increases in order to minimize structural damage. Inhibiting the development of purely plastic conditions would also reduce the vulnerability of continuous framing to off center shifts of the axis of oscillation and the crawling effect of distortions in one direction. Steel without a yield plateau, low steel ratios, and confined compression reinforcement in all sections of a frame would reduce the susceptibility of a reinforced concrete framework to severe damage from severe natural phenomena such as earthquakes and cyclonic winds.