shape effects on the seismic response of on grade steel water tanks with medium h/d ratio using lagrangian approach

water tanks are amongst the most important special structures which are used for storage and providing the needed water on the pick usage time in water supply networks. according to this, investigating the seismic behavior of these structures are of much importance. in current research, the seismic response of circular and square steel water tanks with medium h/d ratio, by the means of lagrangian approach for considering the fluid-structure interaction, is studied. analysis procedure of the whole water-tank system is completed by the means of time history analysis method, using 5 pairs of horizontal components of selected accelerograms, recorded on 3 soil categories of rock, dense, loose and very loose soils and scaled to spectral acceleration level of s_a=0.35g. the response is computed for the filling strategy of empty, 50% full and 100% full conditions of both shapes and the final results are summarized and discussed.