Investigation of Seismic Behavior of Base Isolated Structures Under Near and Far Fault Earthquakes by Wavelet Transform

Year 2022, , 257 - 268, 30.08.2022

Elif Çağda Kandemir

https://doi.org/10.53433/yyufbed.1072327

Abstract

In this study, the seismic behaviour of a structure with seismic base isolators under the near and far fault earthquakes have been investigated by continuous wavelet transform. Seismic responses of the building type structure idealized as a lumped mass-stiffness model with elastomeric isolators which have been placed at the base level have been obtained under near and far fault earthquakes. The most important property of near and far fault earthquakes is the difference in their frequency content. In order to develop a more detailed perspective on the displacement time responses obtained in the time domain, these responses have been presented in the scale (1/frequency)-time plane with the continuous wavelet transform using the Morlet wavelet. The information that could not be obtained from the displacement-time responses has been achieved from the wavelet transform and the differences in the seismic responses in terms of frequency contents have been observed. It has been clarified that during near-fault earthquakes, high frequency contents are spread over a wider time period. In addition, the correlation of displacement responses obtained under the effect of near and far fault earthquakes was measured with the wavelet coherence method and it has been concluded that the behaviours under near- and far-fault earthquakes have low correlation.

Keywords

Continuous wavelet transform, Far-fault earthquake, Near-fault earthquake, Seismic base isolator

Sismik Taban İzolatörlü Yapıların Yakın ve Uzak Fay Depremleri Altındaki Davranışlarının Dalgacık Dönüşümü ile İncelenmesi

Abstract

Çalışmada sismik taban izolatörlü bir yapının yakın ve uzak fay depremleri etkisindeki sismik davranışları sürekli dalgacık dönüşümü yöntemi ile incelenmiştir. Toplanmış kütle-rijitlik modeli kullanılarak idealize edilmiş bina türü bir yapının, taban seviyesine kauçuk izolatör yerleştirilerek yakın ve uzak fay depremleri etkisi altında sismik tepkileri elde edilmiştir. Yakın ve uzak fay depremlerinin en önemli özelliği frekans içeriklerindeki farklılıktır. Zaman tanım alanında elde edilen yer değiştirme tepkilerine daha detaylı bir bakış açısı geliştirmek amacıyla bu tepkiler Morlet dalgacığı kullanılarak sürekli dalgacık dönüşümü ile ölçek (1/frekans)-zaman düzleminde sunulmuştur. Yer değiştirme-zaman grafiklerinden elde edilemeyen bilgiler dalgacık dönüşümlerinden elde edilmiş ve sismik tepkilerin frekans içeriklerindeki farklılıklar net olarak gözlenmiştir. Yakın-fay depremleri altında, yüksek frekans içeriklerinin daha geniş bir zaman dilimine yayıldığı tespit edilmiştir. Buna ek olarak dalgacık uyumu yöntemi ile yakın ve uzak fay depremleri etkisi altında elde edilmiş yer değiştirme tepkilerinin korelasyonu ölçülmüş ve yakın ve uzak-fay depremleri altında davranışların korelasyonlarının düşük olduğu sonucuna varılmıştır.

Keywords

Dalgacık dönüşümü, Sismik taban izolatörü, Uzak-fay depremi, Yakın-fay depremi

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