 Although the triangle shape of the A-frame has been present throughout history, it surged in popularity around the world from roughly the mid-1950s through the 1970s.It was during the post–World War II era that the A-frame acquired its most defining characteristics.A-frame buildings are an old form known in Europe, China, and the South Pacific islands sometimes called a "roof hut" and were simple structures used for utilitarian purposes until the 1950s.