6-2 CONCLUSIONS:Based on the results of this thesis, the following conclusions are drawn:1- During the earthquake shaking the tension side induced in the water tank wall changed from the inside face into the outside face, due to the ground movements during the earthquake. Therefore, these tension stresses must be accounted for when designing ground storage tanks in earthquake susceptible areas.2- The highest values of compression and tension stresses are generated in the water tank body during the earthquake shaking. For water tanks resting on stiffer soils like very stiff clay or on very dense sand, the tension and compression stresses are the highest of all soil types, with approximately equal values in both stiff soil types.3- The rigidity of the reinforced concrete ground tank footing depends mainly on the concrete thickness of that footing. Under static loading condition, the footing rigidity is achieved when its thickness is approximately equal to L/7 of the tank width. It is also noted that the thickness achieving footing rigidity under static loading achieves also the rigidity under dynamic loading.4- Soil permeability is the key element on the amount of pore water pressure generated during an earthquake, it also controls the rate of dissipation of that pressure. For soils having low permeability, high pore water pressures are generated during the earthquake event, with longer dissipation times afterwards. In case of high permeability soils, low pore water pressures are generated during the dynamic action, with less time consumed in the pore water pressure dissipation process.5- The reinforced concrete tank footing settlement depends mainly on the soil type over which the tank is resting. Under static loads, the settlement magnitude in clay soil is higher than that in sand soil. The induced settlement during the earthquake is nearly about 20% of that settlement occurred under static loads. Settlements due to the dynamic action immediately lessen when the earthquake motion diminishes.6- During the earthquake event sand soil beside the reinforced concrete ground tank may move upward causing ground heave, especially in denser soils. This behavior should be taken into consideration when designing such tanks resting on sandy soils.7- The water surface motion inside the tank depends mainly on the type of the soil underneath that tank. For tanks located on sand soils, the water surface motion is less than the motion of water surface inside tanks located on clay soils.