Assessment of Soil-Structure Interaction in Reinforced Concrete Buildings Based on Structure to Soil Stiffness Ratio

Öz

Soil-structure interaction (SSI) results in higher structural damping ratio and elongated fundamental natural period of the building. Generally, these modifications on dynamic properties of the building are regarded to be favorable for dynamic response and SSI is neglected in most of the design codes. However, extensive research points out that neglecting the role of SSI can be a misconception that lead an unsafe design by underestimating the rotational ductility demand and top displacement of the building. Therefore, it is essential to determine if SSI is expected to be significant for safe design of the buildings. In this study, the significance of SSI in design is assessed with the help of the structure to soil stiffness ratio that is considered as the most important parameter controlling the period elongation. Stiffness ratio is determined for buildings with moment-resisting frames and varying number of storeys resting on different soil conditions and a threshold of 0.1 is assumed as the critical value that yields a period elongation of 5%. It is shown that, SSI should be taken into account for buildings founded on site classes ZE, ZD and ZC and can be neglected for site classes ZB and ZA.

Anahtar Kelimeler

• Soil-structure interaction
• Period elongation
• Stiffness ratio

Betonarme Binalarda Zemin-Yapı Etkileşiminin Yapının Zemine Rijitlik Oranı Yardımıyla Değerlendirilmesi

Öz

Zemin-yapı etkileşimi (ZYE) binanın periyodunu uzatırken yapısal sönüm oranını artırır. Binanın dinamik özelliklerindeki söz konusu değişim genellikle dinamik davranış açısından elverişli kabul edildiğinden ZYE tasarım yönetmeliklerinin birçoğunda ihmal edilmektedir. Fakat çok sayıda araştırma ZYE’nin ihmal edilmesinin binanın dönme sünekliği talebinin ve tepe deplasmanının olduğundan az hesaplanması yoluyla güvensiz tasarıma neden olduğunu işaret etmektedir. Bu sebeple ZYE’nin öneminin belirlenmesi güvenli tasarım için gereklidir. Bu çalışmada ZYE’nin tasarımdaki önemi periyot uzamasını kontrol eden en önemli parametre olan yapının zemine rijitlik oranı yardımıyla değerlendirilmiştir. Rijitlik oranı, faklı kat adedine sahip çerçeve taşıyıcı sisteme sahip binalarda farklı zeminler için hesaplanmış ve %5 periyot uzamasına sebep olan 0.1 değeri eşik kabul edilmiştir. ZYE'nin ZE, ZD ve ZC zeminlerde göz önüne alınması gerektiği, ZB ve ZA zeminlerde ihmal edilebileceği gösterilmiştir.

Anahtar Kelimeler

• Zemin-yapı etkileşimi
• Periyot uzaması
• Rijitlik oranı

Kaynakça

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