Abstract: In this paper the response of elastic structure to random earth-quake excitation is analysed. For a frame-wall system, practical calculating formulas are derived and a program in FORTRAN language is made. The program is checked with a numerical example. The envelope of the lateral displacement of the system and the variation regularity of the internal forces are determined from given values of dynamic reliability (first excursion probability) based on the requirement of the operation of the structures.

Key words: viscous fluid, moving body on the water, ship wave