INFLUENCE OF INPUT MOTION SCALING METHODS ON DECOUPLED SSI DYNAMIC ANALYSIS

Year 2022, Volume: 30 Issue: 1, 130 - 140, 15.04.2022

Yusuf Guzel Fidan Guzel

https://doi.org/10.31796/ogummf.1004457

Abstract

Propagation of seismic waves through soil deposits may considerably alter their
characteristics at surface. This ultimately influences the seismic performance of structures.
The influences of soil deposits are included in seismic codes (e.g. Eurocode 8, EC8) by means
of proposed design response spectra for different soil classes used in design or retrofitting
of structures. Nevertheless, a smooth design response spectrum cannot always represent
spectral response of an actual input motion over an engineering period of interest due to
its irregular spectral shape. Subsequently, the seismic performance of a structure may be
insufficient when a design response spectrum is used. The interaction between soil and
structure may also affect the structural behaviour. This study aims to demonstrate the
impact of adoption of input motions and soil deposits with soil classes B, C and D on the
seismic behaviour of one-bay, 1-storey structure modelled in OpenSEES For this purpose,
two different approaches are chosen; (i) seven input motions recorded on ground surface
are modified and applied to the model, (ii) seven outcrop motions are scaled according to
EC8 and processed through the ideal soil deposits by conducting nonlinear site response
analysis, then applied to the model. The results indicate that the model is exposed to more
drift responses when it is on softer soil deposit. In addition, imposing input motions
obtained at surface from nonlinear site response analysis cause higher drift responses than
directly applying input motions.

Keywords

Soil classes, Design response spectrum, Outcrop/surface motion

DEPREM İVME HAREKETİ ÖLÇEKLENDİRME YÖNTEMLERİNİN SSI DİNAMİK ANALİZİ ÜZERİNDEKİ ETKİSİ

Abstract

Sismik dalgaların zemın tabakaları boyunca yayılması, yüzeydeki özelliklerini önemli ölçüde değiştirebilir. Bu nedenle yapıların sismik performansını etkiler. Bu etki, yapıların tasarımında veya güçlendirilmesinde kullanılan farklı zemin sınıfları için önerilen tasarım spektrumları aracılığıyla sismik kodlara (örneğin EC8) dahil edilmiştir. Bununla birlikte, standard tasarım davranış spektrumu, düzensiz spektral şekli nedeniyle gerçek bir deprem ivme hareketinin spektral davranışını tam olarak temsil edemez. Bu nedenle, bir tasarım spektrumu kullanıldığında bir yapının sismik performansı yetersiz olabilir. Bu çalışma, deprem ivme hareketlerinin D, C ve B zemin sınıfları dikkate alınarak OpenSEES'te modellenen tek açıklıklı, 1 katlı yapının sismik davranışı üzerindeki etkisini göstermeyi amaçlamaktadır. Bu amaçla iki farklı yaklaşım seçilmiştir; (i) zemin yüzeyinde kaydedilen yedi deprem ivme hareketi modifiye edilir ve modele uygulanır, (ii) yedi adet outcrop deprem ivme hareketi EC8'e göre ölçeklenir ve nonliner zemin analizi sayesinde yüzeysel deprem ivme hareketleri elde edilir ve ardından modele uygulanmır. Sonuçlar, modelin daha yumuşak zemin üzerinde olduğunda daha fazla drift tepkisine maruz kaldığını göstermektedir. Ek olarak, nonliner zemin analizinden yüzeyde elde edilen ivme hareketlerinin uygulanması, doğrudan ivme hareketleri uygulamaktan daha büyük drift tepkilerine neden olmaktadır.

Keywords

zemin sınıfları, tasarım davranış spektrumu, outcrop ivme hareketi

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