Armen Assatourians - Earthquake Engineering Research Consultant, Yerevan, Armenia,
Sohrab Fallahi - Senior Structural and Earthquake Engineer, ESS Consulting Engineers Co.,Tehran,Iran

In order to investigate the effect of fluid-structure interaction on the maximum displacement of steel elevated water tanks with braced columns, three real models containing capacity of 134, 160 and 82 m3 are selected. Each model is considered to be empty, 25%, 50%,75% and 100% full and is designed according to the 4th version of Iranian 2800 seismic code, taking into account Sa=0.25g & Sa=0.35g spectral accelerations, for soil types 1,2 & 3. On each model, the information of Convective mass, Impulsive mass and the spring stiffness of the convective mass is added, according to Housner’s method. Later, all designed models are subjected to 10 accelerograms, recorded on each soil type and scaled to Sa=0.25g & Sa=0.35g. Total 1800 nonlinear TimeHistory analyses are carried out on finite element models, considering both with and without Soil-Structure Interaction (SSI) effects. Finally the results of nolinear analyses are summerized by computing the average values of the maximum nonlinear displacements, according to soil specifications and percent of filling the tanks, considering both with and without SSI effects. At last, the displacement amplification factor of models with SSI effects to models without SSI effects are computed and discussed. A Modal Pushover analysis is carried out for all models to distinguish the behaviour of the models as well.

Soil-Structure Interaction, Time History Analysis, Fluid-Structure Interaction, Steel Elevated Water Tanks, Nonlinear TimeHistory Analysis