{"references": ["CSI, (2000). SAP-2000, three dimensional static and dynamic finite\nelement analyses of the structures. Computers and Structures, Inc.,\nBerkeley, CA.", "FEMA,(2000). NEHRP recommended provisions for seismic regulations\nfor new buildings. Report no. 356, Federal Emergency Management\nAgency, Washington D.C.", "Iran National Building Code, 519, 2000; Housing and Municipal\nEngineering Ministry.", "ICBO, 1997, Uniform Building Code, International Council of Building\nOfficials, Whittier, CA.", "Applied Projects in Seismic Rehabilitation of Building; Shayanfar M.A.\nand Ghanoonibagha M. Abnous Publication, Tehran, 2010.", "T. Takeda, M.A. Sozen, N.N. Nielsen, \"Reinforced Concrete Response\nto Simulated Earthquakes,\" J. Struct. Engrg. Div., ASCE, V. 96, No. 12,\n1970, pp. 2257-2573."]}

In this paper first, Two buildings have been modeled and then analyzed using nonlinear static analysis method under two different conditions in Nonlinear SAP 2000 software. In the first condition the interaction of soil adjacent to the walls of basement are ignored while in the second case this interaction have been modeled using Gap elements of nonlinear SAP2000 software. Finally, comparing the results of two models, the effects of soil-structure on period, target point displacement, internal forces, shape deformations and base shears have been studied. According to the results, this interaction has always increased the base shear of buildings, decreased the period of structure and target point displacement, and often decreased the internal forces and displacements.