Effects of Multiple Earthquake Sequences on Seismic Behavior of Irregular Buildings

Abstract

Effects of multiple earthquakes are frequently observed after conducted reconnaissance studies in the earthquake affected region. Many structures withstand the main shock without having intense damage. However, when an aftershock hits the previously deteriorated structure, the observed damage is generally altered. There are some cases where the structure withstands the main excitation, however collapsed when an its subjected to a ground sequence. Fewer studies in the literature have focused on the seismic behavior of irregular reinforced concrete structures subjected to multiple earthquakes. This research investigates the effects of multiple earthquake sequences on residual displacement values of irregular reinforced concrete structures. For that reason, three irregular existing reinforced concrete structures are selected, and nonlinear time history analysis are conducted under multiple earthquake sequences. To demonstrate the effect of deteriorations on the material, the selected structures were analyzed using both non-degrading and degrading material models. The results of the analyses revealed the fact that non-degrading models are incapable of estimating the seismic response under multiple earthquake sequences. Hence, degrading material models should be used to capture the deterioration effects accurately. Further, it is concluded that irregularity effects increase the values of the residual displacements.

Keywords

• Aftershocks
• Irregular RC structures
• Degrading material models
• Extended N2 method
• Multiple earthquake

ÇOKLU DEPREM SERİLERİNİN DÜZENSİZ YAPILARIN SİSMİK DAVRANIŞINA ETKİLERİ

Abstract

Depremden sonra hasar görmüş bölgelerde yürütülen yerinde inceleme çalışmalarında çoklu deprem etkileri sıklıkla görülmektedir. Birçok yapı, ana depremi hasarsız ya da az hasarlı atlatırken, rijitlik ve dayanımı azalmış yapıya artçı deprem etkimesi durumunda gözlenen hasar genellikle artmaktadır. Bazı durumlarda yapı ana depremi güvenli bir şekilde atlatırken, artçı depremden sonra göçebilmektedir. Literatürde, çoklu deprem serilerine maruz kalmış düzensiz betonarme yapıların sismik davranışlarını inceleyen az sayıda çalışma vardır. Bu çalışmada, çoklu deprem serilerinin düzensiz betonarme yapıların kalıcı deplasman değerlerine etkilerini araştırılmaktadır. Bu sebeple, düzensiz üç adet mevcut betonarme yapı seçilmiş ve çoklu deprem serileri altında, doğrusal olmayan zaman tanım alanında analizleri gerçekleştirilmiştir. Malzemedeki bozulma etkilerini incelemek için, seçilen yapılar hem azalım etkilerini dikkate alabilen hem de azalım etkilerini dikkate alamayan malzeme modelleri kullanılarak analiz edilmişlerdir. Analiz sonuçlarının incelenmesinden, azalım etkilerini dikkate almayan malzeme modellerinin çoklu deprem serileri altındaki sismik davranışı gerçekçi bir şekilde yansıtamadıkları belirlenmiştir. Bu sebeple bozulma etkilerini doğru olarak yakalayabilmek için azalım etkilerini dikkate alan malzeme modellerinin kullanılması gerekmektedir. Ayrıca, çalışmanın sonucunda düzensizlik etkilerinin kalıcı deplasmanları arttırdıkları belirlenmiştir.

Keywords

• Artçı depremler
• Düzensiz betonarme yapılar
• Azalımsal malzeme modelleri
• Genişletilmiş N2 yöntemi
• Çoklu depremler

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