Tanks with floating roofs are mainly used to store oil or oil products. The tank roof vibrates, and inside fluid is sloshed due to earthquake-induced excitation. Large movement causes the roof to hit the tank body, and in some cases, it will lead to tank damage and possible fire. Controlling the floating roof and reducing its movements will prevent post-quake fire. Seismic retrofitting has been studied in order to prevent severe movements of the roofs through analyzing the location of guide poles in the tanks. In this paper, the time histories of 15 earthquakes with different PGAs up to 3 times the gravity acceleration have been applied to the tank models with a single-deck floating roof, considering fluid height in 3 levels. Seismic retrofits were performed on the arrangement of guide poles and their locations that were applied in 4 different states on the models, and a total of 180 cases were analyzed, including all earthquakes, fluid levels, and different arrangements of guide poles. The analyses show that the conducted retrofits had a positive effect on the tank, reducing the movements of the floating roof. These changes in the floating roof displacement in the vertical direction (sloshing) were different, based on the number of elements, like guide poles, which were fully evaluated.