عنوان مقاله [English]
Base level is one of the important parameters in determining the seismic force and preliminary design of structural sections. Base level, According to 2800 seismic regulations, in cases which the basement perimeter is executed with reinforced concrete walls integrated by structure, in addition with surrounding dense soil; set top of basement walls. The critical issue involved in determining base level is horizontal motion of the land. Usually horizontal movement of the Earth is transferred by shear and friction between the edges of the basement walls and foundation, also this process is completed by soil friction between underside of slabs and shallow. Different conditions such as non-same elevated foundations, soil type around building, soil-structure interaction and type of foundation are impressive on location of base level. Other factors including retaining wall openings in basement, basement floors and soil characteristics around the base structures affect base level coordination. As regards there is cleared definition for base level in different regulation all around the world, sometimes engineers cannot comprehend main purpose correctly, or concepts occasionally are interpreted inaccurately. When structure conditions little different from what normally there is, for example, buildings on slope, or structures on deep foundation such as piles, often experts are conflicted by finding location of base level in this status. In this paper investigations about base level in the past years expressed and studied, also, important issues around them are discussed.
 Kelly, D. (2009). Location of base for seismic design. Structure Magazine, p. 8-11.
 Shahrabadi, H; Nazari, S; Ashrafigol, M. (2015). Investigation of different structural systems and base level variation effect on base shear calculation of high rise buildings. In: The International Conference on Human, Architecture, Civil Engineering and City. City: Tabriz.
 Naghizadeh, A. (2012). Base level investigation in buildings with non-same elevated foundation using soil-structure interaction. Master of civil engineering. Shahrood University of Technology.
 Elias, W. Khouri, M. (2012). Identifying the Fixed Base Location of Building Structures under Seismic Excitation. International Journal of Science and Research (IJSR), 3 (12), p. 2612-2618.
 Civil808, (2013). proposed method around base level problems in design of steel and concrete structures. [online] Available at: http://civil808.com/.
 Moddares, L. (1989). Investigation of vibration base level in semi buried structures during earthquake. Master of civil engineering. University of Tehran.
 Khanmohammadi, M. (1996). Base level investigation in semi buried structures considering soil-structure interaction and probabilistic earthquake. Master of civil engineering. University of Tehran.
 Khajeyee bishk, M. (1998). parametric base level investigation attending to soil influence. Master of civil engineering. Sharif University of Technology.
 Kolahdoozan, S. (2008). Effect of sub-basement structure stiffness in evaluating base level using soil-structure interaction dynamically analysis. Master of civil engineering. University of Tehran.