Hundreds of roofs in the Northeast collapsed after a series of winter storms swept through the region from just before Christmas until the week after Groundhog Day, with minimal thawing in between. The accumulated loads proved more than many commercial flat-roof systems could handle. Photo: Courtesy Town Of Nottingham, N.H. Roof of Nottingham, N.H., town garage proved no match for series of winter storms. Injuries were minimal, but as the tally of structural failures mounted, some began to wonder whether it is time to re-examine building codes if the region is entering a climate-change cycle that will trigger increased precipitation
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.