Betonarme Binalarda Zemin-Yapı Etkileşiminin Sismik Tasarım Parametrelerine Etkileri

Yapıların deprem davranışı birbirlerine bağlı olan zemin, temel ve yapı alt-sistemleri arasındaki etkileşim nedeniyle değişebilmektedir. Genellikle temel, yapının bir bölümü olarak kabul edilir ve bu etkileşim zemin-yapı etkileşimi (ZYE) olarak anılır. ZYE, rijit (ankastre) temel yaklaşımından farklı olarak esnek zemin-temel sistemi, temel sönümü ve yapıya iletilen yer hareketinin filtrelenmesi gibi faktörleri kapsar. Esnek zemin-temel sistemi ve temel sönümüne bağlı olarak sırasıyla ortak sistem periyodunun uzaması ve sönüm oranının artması eylemsizlik etkileşiminin sonuçlarıdır. Öte yandan, serbest saha hareketinin temel girdi hareketinden farklılaşması kinematik etkileşim olarak değerlendirilir. Bu çalışmanın amacı esnek zemin-temel sistemi nedeniyle bina periyodunda gerçekleşen uzamayı farklı yapı sistemlerine sahip binalar ve yerel zemin sınıflarında ortaya koymaktır. Ayrıca periyoda bağlı olan spektral ivme ve deplasman, taban kesme kuvveti ve tepe deplasmanı gibi bazı sismik tasarım parametrelerinin değişimi de gösterilmiştir. ZYE ile elde edilen sismik parametreler, ZYE etkilerinin zayıf zeminler üzerinde yer alan rijit binalar için daha belirgin olduğunu ortaya koymaktadır.

Anahtar Kelimeler:

Zemin-yapı etkileşimi, zemin sınıfı, periyot uzaması

Effects of Soil-Structure Interaction on Seismic Design Parameters of Reinforced Concrete Buildings

The earthquake response of structures can alter due to the interactions between the linked subsystems; soil, foundation and structure. Generally, the foundation is assumed as a part of the structure and the related interaction is then called as soil-structure interaction (SSI). In contrast to approach of rigid (fixed) foundation, SSI comprises factors such as flexible soil-foundation system, foundation damping and filtering the ground motion transmitted to the structure. The period elongation and the increase in the damping ratio of the overall system due to the flexible soil-foundation system and the foundation damping, respectively, are referred as the inertial interaction effects. On the other hand, the difference between the free-field ground motion and the foundation input motion is stated as the kinematic interaction effect. The aim of this study is to determine the period elongation due to the flexible soil-foundation system for buildings with different structural systems resting on soils with different local soil classes. Seismic design parameters related with the period such as spectral acceleration and displacement, base shear force and top displacement are also determined. Seismic parameters obtained with SSI approach point out that the effects of SSI becomes more significant for rigid buildings on weak soils.

Keywords:

Soil-structure interaction, soil class, period elongation,

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