ABSTRACT
The word “shell” was originally used for describing the hard rigid calcareous covering of an animal, like a snail, mussel, abalone, oyster, clam, turtle, etc. Shell structures have been adopted and used in many man-made structures, such as aircraft, automobiles, pressure pipes, silos, water tanks, ships, submarines, rockets, domes, stadiums, tents, chapels, planetariums, opera theatres, cooling towers of power plants, and many others. Leakage of rain water through a shell-type roof is another problem that needs to be addressed properly in the design. Condensation of moisture indoors due to the temperature gradient inside and outside the shells is another pragmatic issue. On September 14, 1970, the Tucker High School gymnasium in the United States, which is in a form of hypar shell, collapsed suddenly and, luckily, there was no fatality but only some injuries. Membrane theory of a shell alone cannot model the behavior of shells near the support.
