While one natural disaster does not predict another and a double disaster is unlikely to repeat itself, Hurricane Irene and the Virginia earthquake, much like the Japanese earthquake and tsunami in March, are chilling reminders that past experience is seldom an infallible guide to the worst-case scenarios thatinform structural design decisions. Engineers would do well to ponder the difference that a slightly stronger earthquake could have made on preparations for and damage from the storm that followed.Taking natural disasters one at a time, 20th-century style, should no longer be an option. Structures are best designed by considering the effects of
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.