Turk J Engin Environ Sci 25 (2001) , 617 – 626. c  T ¨ UB ˙ ITAK Non-Linear Seismic Soil-Structure Interaction Analysis Based on the Substructure Method in the Time Domain Mustafa KUTAN ˙ IS, Muzaffer ELMAS SA ¨ U M¨ uhendislik Fak¨ ultesi, ˙ In¸ saat M¨ uh. B¨ ol¨ um¨ u, Yapı ABD Esentepe Kamp¨ us¨ u, Adapazarı-TURKEY Received 02.08.2000 Abstract This paper presents an idealized 2-dimensional plain strain finite element seismic soil-structure interaction (SSI) analysis based on a substructure method by using original software developed by the authors. To investigate the effects of SSI the following types of analysis were performed: linear SSI analysis and non-linear SSI analysis. For the same structure, analysis was carried out by the procedure without the consideration of soil-structure interaction. These computations were achieved for different peak accelerations: 0.15g, 0.30g and 0.45g. In another case for a different site soil with a shear wave velocity of 200, 300 and 500 m/s, a linear SSI analysis was performed. In the analysis, the radiation condition was fully accounted for, the soil plasticity was modeled with the Von Mises failure criterion, basemat uplift was not considered, and the action of gravity was not taken into consideration. Key Words: Seismic soil-structure interaction, substructure formulation, finite element method Sismik Y¨ ukler Altında Yapı-Zemin Etkile¸ siminin Zaman Tanım Alanında Altsistem Yakla¸ sımı C ¸er¸cevesindeAnalizi ¨ Ozet Bu ¸ calı¸ smada 2-boyutlu d¨ uzlem ¸ sekilde˘gi¸ stirme elemanı olarak sonlu elemanlarla modellenen bir sistemin altsistem yakla¸ sımı¸cer¸ cevesinde, sismik y¨ ukler altında yapı-zemin dinamik etkile¸ simi incelenmi¸ stir. Yapılan hesaplamalarda yazarlar tarafından geli¸ stirilen program kullanılmı¸ stır. Etkile¸ simi izlemek amacıyla sonsuz rijit zemin, lineer yapı-zemin etkile¸simi ve lineer olmayan yapı-zemin etkile¸ simi ile ilgili durumlar, farklı d¨ uzeydeki ivme de˘gerleri ve farklı zemin rijitliklerii¸cin (Vs=200, 300 ve 500 m/s) hesaplamalar yapılmı¸ stır. Burada radyasyon ko¸ sulunun tam olarak sa˘glandı˘gı, zemin plastik davranı¸ sının Von Mises akma kriteri ile belirlendi˘gi, zemin ayrılma etkisinin ve yapının kendi a˘gırlı˘gının ihmal edildi˘gi bir ¸c¨ oz¨ umleme yapılmı¸ stır. AnahtarS¨ozc¨ ukler: Dinamik yapı-zemin etkile¸ simi, altsistem form¨ ulasyonu, sonlu elemanlar y¨ontemi Introduction During the last quarter of the 20th century, the importance of dynamic soil-structure interaction for several structures founded on soft soils was well rec- ognized. If not accounted for in analysis, the accu- racy in assessing structural safety in the face of earth- quakes cannot be accounted for adequately. For this reason, seismic soil-structure interaction analysis has become a major topic in earthquake engineering. In dealing with the analysis of dynamic soil- structure interaction, one of the most difficult tasks 617