The advent of air- and spaceflight vehicles and that of nuclear explosions as well as the trend of constantly increasing and higher structures have brought attention to the need for better understanding of the dynamic response of such a system. The knowledge of free and forced large amplitude vibrations of structures or parts of it, as well as the response of them to pulse excitations, are of pronounced influence upon their design. Whether one deals with aerospace structures or civil structures, such as bridges or buildings, one is faced with the prediction of loads due to some wind or gusts.