Seismic Vulnarability Assessment of Reinforced Concrete Buildings Located in Esenler District of İstanbul
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Afyon Kocatepe Üniversitesi Fen ve Mühendislik Bilimleri Dergisi Afyon Kocatepe University Journal of Science and Engineering AKÜ FEMÜBİD 18 (2018) 015604 (285-294) AKU J. Sci. Eng. 18 (2018) 015604 (285-294) DOİ: 10.5578/fmbd.66804 Seismic Vulnarability Assessment of Reinforced Concrete Buildings Located in Esenler District of İstanbul Hasan Özkaynak1, Ayşe Elif Özsoy Özbay2 1,2 Beykent Üniversitesi, Mühendislik-Mimarlık Fakültesi, İnşaat Mühendisliği Bölümü, İstanbul. e-posta: [email protected], [email protected] Geliş Tarihi:03.11.2017 ; Kabul Tarihi:03.04.2018 Abstract Istanbul is one of the largest cities of Turkey which is located on the regions where there is high seismic activities. Recent studies performed on mid-rise reinforced concrete (RC) structures showed that majority of the existing building stock does not conform to current seismic code requirements and they can be evaluated as vulnerable structures. The seismic performance evaluation of an existing buildings Keywords can be conducted by using nonlinear procedures stated in Turkish Earthquake Code (TEC-07). According Rapid visual screening; to the code, an existing building completing its economic lifetime and/or having a performance level in between “Life Safety” to “Collapse Prevention” under the effect of Design Earthquake is defined as Seismic assesment; “building under seismic risk”. Before going into such a detailed seismic evaluation procedure for each Street visual surveying; building, there is a need for regional screening surveys to rank the building stock in terms of the Reinforced concrete potential seismic hazard. This study aims to assess the seismic vulnerability of a group of midrise RC structures; Earthquake buildings located in Esenler District of İstanbul employing the Rapid Visual Screening (RVS) procedure. performance. In this study, valuable results have been derived to rank the buildings in terms of seismic vulnerability of existing structures located in Istanbul. It is concluded that the number of stories is the key parameter to change the priority range of the building from lowest to highest level. Majority of the buildings with the highest priority level (0≤PS≤30) suffer from the parameters related with poor construction quality, soft story irregularity and the heavy overhang. The aforementioned method could be used to estimate the performance scores of the buildings to determine the priority for more detailed seismic risk assessment procedures. İstanbul’un Esenler İlçesinde yer alan Betonarme Yapıların Sismik Hasar Görebilirliğinin Değerlendirilmesi Özet İstanbul, Türkiye'nin sismik aktivitesi yüksek olan en büyük şehirlerinden biridir. Orta yükseklikteki betonarme yapılar üzerinde yapılan son çalışmalar, mevcut bina stokunun çoğunluğunun güncel deprem yönetmeliği şartlarına uymadığını dolayısıyla hasar almaya meyilli yapılar olarak değerlendirilebileceğini göstermiştir. Mevcut binaların deprem performansının değerlendirilmesi, Türk Keywords Deprem Yönetmeliği (TEC-07)'de belirtilen lineer olmayan yöntemler kullanılarak yapılabilir. Mevcut Hızlı görsel tarama yönetmeliğe göre, ekonomik ömrünü tamamlayan ve/veya tasarım depremi etkisinde performans teknikleri; Sismik seviyesi "Can Güvenliği" ile "Göçmenin Önlenmesi” arasında bulunan yapı, "riskli bina" olarak değerlendirme; tanımlanmaktadır. Her bina için böylesine detaylı bir deprem değerlendirme yöntemine gerek Sokaktan görsel kalmadan, bina stokunun potansiyel sismik tehlike açısından sıralamak amacıyla bölgesel tarama anketlerine ihtiyaç duyulmaktadır. Bu çalışma, İstanbul Esenler İlçesi'nde bulunan bir grup orta tarama; Betonarme yükseklikteki betonarme binanın “Hızlı Görsel Tarama (RVS)” yöntemini kullanarak deprem güvenliğini yapılar; Deprem belirlemeyi amaçlamaktadır. Bu çalışmada İstanbul'da bulunan mevcut yapıların deprem güvenliğine performansı. göre sıralandırılması açısından önemli sonuçlar elde edilmiştir. Kat adedinin, yapının potansiyel risk seviyesini en düşükten en yükseğe değiştirebilen bir anahtar parametre olduğu sonucuna varılmıştır. Kötü inşaat kalitesi, yumuşak kat düzensizliği ve ağır çıkma ile ilgili parametreler, en yüksek risk seviyesine sahip olan binalarda (0≤PS≤30) ortak zafiyetler olarak belirlenmiştir. Söz konusu yöntem, daha detaylı deprem riski değerlendirmesi için önceliğin belirlenmesi amacıyla binaların performans puanlarını tahmin etmekte kullanılabilmektedir. © Afyon Kocatepe Üniversitesi Seismic Vulnarability Assesment of Reinforced Concrete Buildings Located in Esenler District of İstanbul, Özkaynak ve Özbay. 1. Introduction the size, the photograph and documentation of the observed structural system. Documentation The majority of the building stock in Istanbul is consists of three main forms which correspond to under seismic risk, considering the population, the the regions of low, moderate and high seismicity. site conditions, and its distance to the North Accordingly the seismic hazard scores of the Anatolian Fault. Moreover, the most of the buildings surveyed buildings could be determined. The final do not comply with the current seismic code numerical score is a main indicator which enables to requirements. Assessment of seismic performance assess the seismic resistance. Tischer et al. (2012) of a multistory reinforced concrete (RC) structure proposed a vulnerability assessment method based mainly requires nonlinear analysis including on rapid seismic screening of school buildings. The determination of reinforcement ratio, material method is able to classify the buildings according to properties such as concrete and reinforcement level of irregularities and potential pounding effect. strengths through experiments, and as built The final score is obtained by performing the dimensions of the structural system. The legal method and it includes the effects of horizontal and judgment about the seismic safety of the buildings vertical irregularities deterioration, short column requires a detailed procedure for the building effects and the local site conditions. An alternative owner, the structural engineer and the local procedure is proposed by Sucuoglu et al. (2003). authority. However, it is not practical to perform The rapid screening procedure cannot be employed detailed assessment studies for each building in a for the detailed seismic evaluation of a single city scale. Thus, there is a need for scheduled existing building. The method is valid for a group of screening surveys at each region in Istanbul to buildings to determine the regional profile in terms decide for the renewal or retrofitting of the of seismic risk. Moreover, the number of the buildings which should be coordinated by the screened buildings should be statistically sufficient. government and local authorities. Assessing the The method requires survey parameters such as seismic risk of a building stock may be conducted by number of stories; existence of a soft story, heavy various methodologies without detailed analysis. overhangs short columns and pounding between These methods provide rapid and reliable statistical adjacent buildings. The apparent building quality, data of the existing buildings in order to develop topographic effects and the local soil conditions inventories of the building stock for the earthquake should be determined within this surveying disaster planning or the evaluation of regional procedure. Performance score (PS) of the screened rehabilitation needs (Sucuoglu et al. 2003; Ozcebe building is determined by the vulnerability scores et al. 2003; Sozen et al. 1997; Gulkan et al. 1999; (VS) based on the observed survey parameters and Yakut et al. 2003; FEMA P-154, 2015). the base scores which vary according to the seismic In general, the screening methods in the literature zones related with peak ground velocity (PGV). The require typical building data such as building method of Sucuoglu et al. (2003) had been location, age, the structural system, the number of employed for a multiple levels of seismic stories, structural irregularities and the quality of vulnerability assessment for the existing building the construction which could be simply observed stock in Zeytinburnu District of Istanbul (Özcebe et from the street view. FEMA P-154 (2015) provides al. 2006). Regarding the seismicity, the population Rapid Visual Screening (RVS) of buildings to identify, and the poor construction quality, Zeytinburnu and rank the buildings that are potentially District were chosen to be the pilot application of seismically hazardous for building officials and seismic assessment within the scope of Earthquake inspectors, government agency and private-sector Masterplan for the Istanbul (Istanbul Metropolitan building owners named as "RVS authority". The RVS Municipality, 2003). Further applications of the methodology is based on visual observation of the method of Sucuoğlu (2003) had been conducted for screened building from the street by completing the vulnerability assessment of the building stocks in building information. The method needs the use, the city of Eskisehir (Albayrak et al. 2015) and 286 Seismic Vulnarability Assesment of Reinforced Concrete Buildings Located in Esenler District of İstanbul, Özkaynak ve Özbay. Bitlis (Işık et al. 2013) which are both located on is one of the developing regions in İstanbul with a highly active seismic zones of Turkey. The same great number of urban renewal practices. The method had also been used for the seismic selected group of buildings is a representative vulnerability assessment of the reinforced