Huseyin BILGIN
Professor of Structural Engineering
Publications
Influence of interventions on the seismic performance of URM buildings designed according to pre-modern codes
JournalOn November 26,2019, an earthquake of magnitude 6.4 hit Durres city, Albania. After the earthquake, the inspection carried out by the authors in the region has provided relevant findings regarding the methods of construction, quality of the materials and the performance of structures. The dominant building types in the Albanian building stock comprise unreinforced masonry (URM) structures with load-bearing masonry walls. These units suffered the worst damage. Dynamic response of masonry is highly nonlinear, and generally shows high vulnerability to seismic loading. Moreover, many buildings of this type have undergone structural interventions like adding floors, or wall openings, especially in the first floors of the buildings, which are parallel to the main roads, because of the great demand for shops and stores. This paper aims at making a seismic performance assessment of the intervened buildings based on macro-element modeling approach. Due to its efficiency, this approach is becoming popular among practitioners and field experts in this area and allows simulating the non-linear behavior of masonry buildings. This method is applied to two old masonry buildings from the Albanian construction practice that are representatives of mid-size residential buildings with and without interventions. It must be said that in Albania, masonry buildings have been built using templates all over the country, so both models with and without intervention are common. Capacity curves of the investigated buildings are derived to assess the most probable seismic response of the investigated housing construction in the region as well as to evaluate the seismic performance of the tested structures.
The effect of material strength and discontinuity in RC structures according to different site-specific design spectra
JournalSeismic-induced damages in reinforced-concrete (RC) buildings were primarily associated with materials’ low strength and poor properties. This study aims to investigate the seismic response of RC structures according to the different material’s strength and design spectra. Adaptive static pushover and eigenvalue analysis were performed for four different design spectra, five types of concrete, and two reinforcement grades. Four different design spectra were obtained by considering discrete geographical locations with different earthquake risks via the updated Turkish Earthquake Hazard Map 2018. Structural analysis was carried out for a sample RC building using these spectrum curves and material strengths. It has been observed that the structure becomes more rigid as the strength of concrete increases. This situation manifested itself with an increase in period values and a decrease in the stiffness values. Stiffness values of the building are independent of reinforcement. As the concrete strength decreases, the structure’s seismic capacity decreases while the displacement’s demand for predicted performance levels increases. Moreover, an increase in the tensile strength of reinforcements substantially increases the seismic capacity of the building. The study also determines that the site-specific design spectra obtained for different provinces are used in the analysis affects the demand displacements values considerably. The material differentiation between the stories in the building was also examined in this study. It can be a source in terms of how material discontinuity affects building performance.
Model of seismic design lateral force levels for the existing reinforced concrete European building stock
JournalAs part of the development of a European Seismic Risk Model 2020 (ESRM20), the spatial and temporal evolution of seismic design across Europe has been studied in order to better classify reinforced concrete buildings (which represent more than 30% of the approximately 145 million residential, commercial and industrial buildings in Europe) and map them to vulnerability models based on simulated seismic design. This paper summarises the model that has been developed to assign the years when different seismic design levels (low code, moderate code and high code) were introduced in a number of European countries and the associated lateral forces that were specified spatially within each country for the low and moderate codes for typical reinforced concrete mid-rise buildings. This process has led to an improved understanding of how design regulations evolved across Europe and how this has impacted the vulnerability of the European residential building stock. The model estimates that ~ 60% of the reinforced concrete buildings in Europe have been seismically designed, and of those buildings ~ 60% have been designed to low code, ~ 25% to moderate code and 15% to high code. This seismic design model aims at being a dynamic source of information that will be continuously updated with additional feedback from local experts and datasets. To this end, all of the data has been made openly available as shapefiles on a GitLab repository.
STRUCTURAL PERFORMANCE OF URM SCHOOL BUILDINGS DURING THE 2019 ALBANIA EARTHQUAKES
JournalThis paper aims to study the seismic performance of school buildings, which have been built in accordance with template unreinforced masonry [URM] school projects in Albania. For this purpose, the most widely used two template designs which were damaged during the 2019 Durrës (Albania) Earthquakes, have been selected. Analytical models of each school were prepared following the experimental data on the quality of the masonry constitutive components of the selected school buildings. Geotechnical investigations were deployed to obtain the soil characteristics of the area where the schools’ foundations are located. Nonlinear static analyses have been performed to obtain the seismic capacity, the performance point and the damage level states. The performance-based method has been used for that purpose. The detailed examination of capacity curves and performance evaluation identified deficiencies and weak parts of the school building blocks. Results have shown that existing school buildings constructed pre-modern codes are far from satisfying the required performance criteria, suggesting that urgent response and necessary measures should be put into action.
Abstract- Recent earthquakes occurred in many parts of the world have shown that unreinforced masonry [URM] buildings constructed according to older codes may constitute an important source of risk. It is known that the mechanical response of the masonry structures depends on several factors including the compressive and shear strength of its constituents, bricks shape as well as the volumetric ratio between the wall texture and components. In this study, the effects of the material choices of a particular type of masonry buildings were studied. The typology chosen in this study represents a typified masonry building of the current Albanian building stock; these buildings were mostly built between 1977-78 and thus were designed without considering the seismic requirements proposed in today’s modern codes. This template building has been constructed in different regions of the country with the same architectural and structural configuration in two versions; red clay bricks and silicate bricks. The aim of this study is to investigate the influence of these two different materials on the seismic response of the selected masonry building. The evaluation is based on the use of nonlinear static analyses, performed by using TREMURI software. In order to estimate the reliable seismic response for this typology, extensive research in terms of historical information, structural characterization and the definition of the inherent material parameters has been executed. Upon the evaluation of the obtained results, in contrast to the type of buildings constructed by clay masonry, calcium silicate one showed a stiffer and slightly stronger response. However, at similar values of in-plane, lateral drift they exhibited more brittle response yielding unforeseen damage during seismic excitations.
Comparison of near and far-fault ground motion effects on low and mid-rise masonry buildings
JournalAbstract
This paper presents a comparison of near and far-fault ground motion effects on the seismic response of masonry structures, using nonlinear methods. To compare the influence on low to moderate rise buildings, a detailed field investigation and archive study were executed in Albania. Based on the archive and detailed field investigation over a hundred real residential masonry buildings constructed between 1963-1978, seven masonry buildings of 2-5 stories were selected to reflect the commonly constructed template designs. Analytical models of each building were prepared following the experimental data on the quality of the masonry constitutive components of the selected buildings. Seismic deformation capacities of each building were obtained by nonlinear static analyses. Inelastic time history analysis was used to predict the seismic displacement demands of the studied buildings. The significance of the findings is further investigated by examining the nonlinear behavior of a group of realistic buildings subjected to near and far-fault ground recordings. Results indicate that there is a remarkable difference in the seismic response of masonry structures between near and far-fault records. It can therefore be concluded that near-fault earthquakes may have significantly more damage potential on masonry structures than far-fault records.
A Simple Approach for the Design of Ductile Earthquake-Resisting Frame Structures Counting for P-Delta Effect
JournalAbstract
Effects of the isolation parameters on the seismic response of steel frame
JournalIn this paper, an analytical study was carried out to propose an optimum base-isolated system for the design of steel structures equipped with lead rubber bearings (LRB). For this, 5 and 10-storey steel moment resisting frames (MRFs) were designed as Special Moment Frame (SMF). These two-dimensional and three-bay frames equipped with a set of isolation systems within a predefined range that minimizes the response of the base-isolated frames subjected to a series of earthquakes. In the design of LRB, two main parameters, namely, isolation period (T) and the ratio of strength to weight (Q/W) supported by isolators were considered as 2.25, 2.5, 2.75 and 3 s, 0.05, 0.10 and 0.15, respectively. The Force-deformation behavior of the isolators was modelled by the bi-linear behavior which could reflect the nonlinear characteristics of the lead-plug bearings. The base-isolated frames were modelled using a finite element program and those performances were evaluated in the light of the nonlinear time history analyses by six natural accelerograms compatible with seismic hazard levels of 2% probability of exceedance in 50 years. The performance of the isolated frames was assessed in terms of roof displacement, relative displacement, interstorey drift, absolute acceleration, base shear and hysteretic curve.
Earthquake performance assessment of low and mid-rise buildings: Emphasis on URM buildings in Albania
JournalThis study focuses on the earthquake performance of two URM buildings having typical architectural
configurations common for residential use constructed per pre-modern code in Albania. Both buildings are unreinforced clay brick masonry structures constructed in 1960 and 1984, respectively. The first building is a three-storey unreinforced one with masonry walls. The second one is confined masonry rising on five floors. Mechanical characteristics of masonry walls were determined based on experimental tests conducted according to ASTM C67-09 regulations. A global numerical model of the buildings was built, and masonry material was simulated as nonlinear. Pushover analyses are carried out to obtain capacity curves. Displacement demands were calculated according to Eurocode 8 and FEMA440 guidelines. Causes of building failures in recent earthquakes were examined using the results of this study. The results of the study showed that the URM building displays higher displacement and shear force demands that can be directly related to damage or collapse. On the other hand, the confined one exhibits relatively higher seismic resistance by indicating moderate damage. Moreover, effects of demand estimation approaches on performance assessment of URM buildings were compared. Deficiencies and possible solutions to
improve the capacity of such buildings were discussed.
Effects of structural irregularities on low and mid-rise RC building response
JournalDuring the recent earthquakes, it has been observed that structural irregularities are one of the main reasons of the building damage. Irregularities are weak points in a building which may cause failure of one element or total collapse of the building dur-ing an earthquake. Since Albania is a country with moderate seismicity which has been hit by earthquakes of different magnitudes many times establishes the need to study the effect of irregularities is well-founded. The main structural irregularities encountered in Albanian construction practice consist of short column, large and heavy overhangs and soft story. In this study, these types of irregularities are consid-ered in two different types of buildings, low and mid-rise reinforced concrete frame buildings represented by 3- and 6- story respectively. Pushover analyses are de-ployed to get the effect of structural irregularities on RC building response. A building set is chosen to represent the existing construction practice in the region; regular framed building and buildings with irregularities such as soft stories, short columns, heavy overhangs and the presence of soft story with heavy overhangs. The analyses have been conducted by using ETABS and Seismosoft software. Pushover curves of building set are determined by nonlinear static analysis in two orthogonal directions. Comparative performance evaluations are done by considering EC8 and Albanian Seismic codes (KTP-N2-89). From the obtained results, it is observed that low and mid-rise structures with soft story- two sided overhangs and short column are more vulnerable during earthquakes.
Predicting the seismic performance of typical R/C healthcare facilities: emphasis on hospitals
JournalReinforced concrete (RC) type of buildings
constitutes an important part of the current building stock
in earthquake prone countries such as Albania. Seismic
response of structures during a severe earthquake plays a
vital role in the extent of structural damage and resulting
injuries and losses. In this context, this study evaluates the
expected performance of a five-story RC healthcare facility,
representative of common practice in Albania,
designed according to older codes. The design was based
on the code requirements used in this region during the
mid-1980s. Non-linear static and dynamic time history
analyses were conducted on the structural model using the
Zeus NL computer program. The dynamic time history
analysis was conducted with a set of ground motions from
real earthquakes. The building responses were estimated in
global levels. FEMA 356 criteria were used to predict the
seismic performance of the building. The structural
response measures such as capacity curve and inter-story
drift under the set of ground motions and pushover analyses
results were compared and detailed seismic performance
assessment was done. The main aim of this study is
considering the application and methodology for the
earthquake performance assessment of existing buildings.
The seismic performance of the structural model varied
significantly under different ground motions. Results indicate
that case study building exhibit inadequate seismic
performance under different seismic excitations. In addition,
reasons for the poor performance of the building is
discussed.
Effects of Soft storey Irregularity on RC building Response
Conference PaperAlbanian building stock is composed of reinforced concrete and masonry buildings. Most of these buildings are designed with Old Albanian Codes (KTP Codes) and some of them are constructed without any project. Considering these facts and the observations done in Albanian construction industry, presence of structural irregularities is very common in these buildings. Irregularities are weak points in the building which may cause fail of one element or total collapse of the building during an earthquake. Irregularities encountered in Albanian construction practice consist of short column, large and heavy overhangs, reinforcement details and soft story irregularity. Since Albania is a high seismic country which has been hit many times from earthquakes of different magnitudes establishes the need to study the effect of irregularities. Among all these irregularities in this study is taken in consideration the soft story effect under seismic loads in low and mid-rise buildings of Albanian construction practice. In order to get the effect of soft story irregularity in RC buildings several number of Nonlinear Static (Pushover) Analyses are done for regular frames, frames with soft story because of higher height and lack of masonry infill walls in ground story or because of the presence of both cases for the two types of structures, 3 and 6-story frames representing low and mid-rise buildings respectively. The analysis has been performed by ETABS software. The results of the analyses indicate that low and mid-rise structures with soft story irregularity due to absence of infill walls and higher height of ground story are more vulnerable during earthquakes.
Earthquake Performance Assessment of a Low-rise URM Building
Conference PaperIn the present paper, seismic performance assessment of a typical low-rise unreinforced masonry (URM) building, which has been built in accordance with template designs in Albania, has been performed. For this purpose, one of the most widely used template designed URM building typology has been selected as a good representatives of residential building stock. This type shows some particular features, typical of the traditional construction techniques at that time which could be identified as the additional potential damage sources. The building was designed and constructed in 1960 and contains details which are typical of that construction period of the region. Material properties are assessed based upon experimental test results. Then, the buildings is modeled and analyzed as 3-D assembly of finite elements. The earthquake ground motion to be used in performance assessment is determined through probabilistic seismic hazard assessment. The seismic response of the buildings has been evaluated for various earthquake levels based on Eurocode 8 and FEMA 440 guidelines. Upon the evaluation of the obtained results here for the earthquake performance of this type of buildings, useful conclusions are drawn on the strength and nonlinear behavior of masonry subjected to earthquake actions.
Seismic performance evaluation of an existing school building
JournalAbstract-
A great part of existing RC structures built in Turkey is that they have been designed without considering seismic-induced actions and seismic criteria for strength and ductility design. In this context, after the recent devastating earthquakes in Turkey, there has been a concerted effort to address the seismic vulnerability of existing public buildings in Turkey. The need for the evaluation and strengthening of these public buildings have come into focus following the enormous loss of lives and property during the past earthquakes. This study aims to assess the seismic performance evaluation of a typical school building in accordance with the rules of Turkish Earthquake Code-2007. The performance analysis is carried out by using nonlinear static analysis. The analytical solutions show that the intended performance level has not been satisfied for this building and decided to retrofit the structural system. The proposed procedure is applied to the retrofitted system and the obtained results are tabulated and discussed.
GENERATION OF FRAGILITY CURVES FOR TYPICAL R/C FACILITIES: EMPHASIS ON PUBLIC HOSPITALS IN TURKEY (DOI: 10.1061/(ASCE)CF.1943-5509.0000806)
JournalAbstract-
This study uses fragility curves to focus on the seismic safety evaluation of RC hospital buildings in Turkey. Three hospital buildings with varying heights of 3–5 stories are selected, and a set of fragility curves are generated for each class. The major parameters considered in this study are the number of stories, lateral stiffness, strength, and displacement capacities of the selected template designs. A large number of pushover and time history analyses are deployed under a set of 100 strong ground motion records. Fragility curves are generated based on the analysis results for each of the typical buildings. Peak ground velocity (PGV) is selected as the measure of seismic intensity. From the generated sets of the fragility curves, it is observed that damage probabilities are significantly affected by the concrete and detailing quality. Using the constructed fragility curves, collapse probabilities of existing public buildings were estimated according to PGV values. The estimated damage by fragility analyses is compared with past studies related to RC buildings in the region. Hence, analytical fragility curves developed in this study can increase the effectiveness of seismic assessment of essential health care facilities with template designs in the Turkey region.
Read More: http://ascelibrary.org/doi/10.1061/%28ASCE%29CF.1943-5509.0000806
Geleneksel Mimaride Kubbeli Örtü Sistemlerinin Yapısal Davranışı (Structural Behaviour of Domed Roof Systems in Traditional Architectural Buildings)
Conference PaperAbstract –
Domes in traditional architectures were not only used alone as covering spaces but they were also used as a various combinations of semi-domes based on larger main and flanking areas. To determine the structural behavior and the load carrying mechanisms of the monolithic systems formed main dome, arches, pendentives and semi-domes is now possible through current numerical methods based on computer-aided analysis. One of the first steps to protect the historical buildings should definitely be to understand the structural behaviour of these buildings. In this study, considering the dome system and its geometrical features of Suleymaniye Mosque in Istanbul, the theoric roof systems with arches on four sides, arches on two sides and semi domes on two sides, semi domes on three sides and arch on one side and semi domes on four sides were statically analyzed under their dead loads by Structural Analysis Programme (SAP2000) based on finite element methods. As a result, the structural behaviour of main
Sinan Kubbeli Yapılarında Mekan Örtü Sistemlerinin Yapısal Davranışı
Conference PaperÖz:
Mimar Sinan kubbelerini, mekan örtüsünde tek olarak kullandığı gibi mekan
genişlemesine bağlı olarak yarım kubbelerin çeşitli kombinasyonlarıyla beraber de
kullanmıştır. Merkezi ana kubbe, kemer, pandantif, ve yarım kubbelerin birleşmesinden
oluşan bu tür monolitik taşıyıcı sistemlerin yük taşıma mekanizmasını ve yapısal
davranışını tespit etmek, günümüzün bilgisayara dayalı sayısal hesap metotları yardımıyla
mümkün olabilmektedir. Bugün gelişmiş toplumlar, geçmişin kültür ve sanat birikiminin
somut bir simgesi olan ve yüzyıllardır iklimsel koşullar, savaşlar ve deprem gibi doğal
afetlere karşı koyarak varlığını sürdüregelen geleneksel yapıların korunmasına önem
vermektedirler. Tarihi yapıların korunmasında atılacak ilk adımlardan biri, şüphesiz taşıyıcı
strüktürlerin yapısal davranışını anlamak olmalıdır. Bu çalışmada, İstanbul’daki Şehzade
Camisi mekan örtü sistemi ile bu örtü sisteminin geometrik boyutları esas alınarak; yarım
kubbesiz dört eşit rijitlikli kemere oturan, iki yarım kubbeli, üç yarım kubbeli ve dört yarım
kubbeli teorik örtü sistemlerinin zati yükleri altında, sonlu elemanlar yöntemine dayalı
SAP2000 Yapısal Analiz Programı ile statik analizleri yapılmıştır. Analizler sonucunda;
ana kubbe, kemer, yarım kubbe ve pandantif dörtlüsünün karşılıklı yapısal etkileşimi
belirlenmiş ve her sistemin yapısal davranışı sayısal olarak ortaya konmaya çalışılmıştır.
Kamu Yapılarının Performanslarının Doğrusal Ötesi Davranış Modelleriyle Değerlendirilmesi
Conference PaperÖz: Mevcut fonksiyonlar ve deprem sonrası muhtemel kullanımlar gözönüne alındığında
kamu binaları (telekomünikasyon, hastane, okul, vb.), olası bir deprem felaketi sonrası
ayakta kalması gereken yapılardır. Ülkemizde yaşanan son depremler, birçok kamu hizmet
binamızın içinde çalışan insanlara deprem durumu sözkonusu olduğunda, yeteri kadar can
güvenliği sağlamakta zorlandığını göstermiştir. Son yıllarda kamu binalarının deprem
risklerinin gözden geçirilerek deprem performanslarının artırılması için gerekli
çalışmalarının yapılması yönünde çabalar başlamıştır. Önceliklerin iyi belirlenerek planlı ve
ekonomik bir çalışmanın yapılabilmesi için her bir binanın tek tek incelenmesinden önce,
yaygın kullanılan tip projeler üzerinde çalışmalar yapılarak proje eksiklikleri belirlenebilir.
Bu çalışmada, doğrusal ötesi statik analiz ve performansa dayalı yapı tasarımı yaklaşımı
ilkeleriyle, seçilecek yaygın kullanılan iki tip kamu binası projesinin performans
değerlendirmesi yapılmış, projelerin zayıf noktaları belirlenmiş ve Afet Bölgelerinde
Yapılacak Yapılar Hakkında Yönetmelik (ABYYHY) –1998’in öngördüğü değerler ile
kıyaslama yapılmıştır. SAP2000 programında oluşturulacak üç boyutlu modelde her eleman
için oluşturulacak kullanıcı tanımlı plastik mafsal özellikleri dikkate alınmıştır. Plastik
mafsal özelliklerinin oluşturulmasında eleman boyutları, boyuna donatı ve etriye oranları
kullanılarak sargılı beton davranışı dikkate alınmıştır. Bu çalışmada elde edilen sonuçlar
daha sonra yaygın olarak yapılacak bina bazındaki çalışmalara ışık tutacaktır.
Tip Bir Kamu Yapısının Performans Değerlendirmesi
Conference PaperÖZ:
Türkiye’de son otuz yılı aşkın bir dönemde bir bölümü büyük afet boyutunda olmak üzere toplam on beş yıkıcı deprem yaşanmıştır. 13 Mart 1992 Erzincan ve 17 Ağustos 1999 Kocaeli başta olmak özere bazılarındaki hasarların büyüklüğü deprem olgusunu, kamuoyunun dikkatini çeken toplumsal bir konu haline dönüştürmüştür. Ülkemizde yaşanan bu son depremler, birçok kamu hizmet binamızın içinde çalışan insanlara deprem durumu sözkonusu olduğunda, yeteri kadar can güvenliği sağlamakta zorlandığını göstermiştir. Son yıllarda kamu binalarının deprem risklerinin gözden geçirilerek deprem performanslarının artırılması için gerekli çalışmalarının yapılması yönünde çabalar başlamıştır. Önceliklerin iyi belirlenerek planlı ve ekonomik bir çalışmanın yapılabilmesi için her bir binanın tek tek incelenmesinden önce, yaygın kullanılan tip projeler üzerinde çalışmalar yapılarak proje eksiklikleri belirlenebilir. Bu çalışmada, doğrusal ötesi statik analiz ve performansa dayalı yapı tasarımı yaklaşımı ilkeleriyle, seçilecek yaygın kullanılan bir tip kamu binasının performans değerlendirmesi yapılmış, projenin zayıf noktaları belirlenmiş ve Afet Bölgelerinde Yapılacak Yapılar Hakkında Yönetmelik 1998’in öngördüğü değerler ile kıyaslama yapılmıştır.
Orta Katlı Betonarme Yapılar için Performans İstemi Hesaplama Yöntemlerinin Karşılaştırılması
Conference PaperÖZ:
Yurdumuz mevcut yapı stokunun büyük bölümünün deprem performansı açısından yeterli güvenlik seviyesinde
olmadığı bilinen bir durumdur. Yapı stokunun iyileştirilmesi için atılması gereken ilk adım mevcut
yapıların değerlendirilmesidir. Bu değerlendirme işleminin önemli aşamalarından biri deplasman isteminin
belirlenmesidir. Bu çalışmanın amacı deplasman isteminin hesabında kullanılan kapasite spektrumu (ATC-
40), deplasman katsayıları (FEMA-356, FEMA-440) ve 2006 Afet Bölgelerinde Yapılacak Binalar Hakkında
Yönetmelik (AY-2006) Bölüm 7C’de önerilen yöntemlerle bulunan değerler birbirleri ve seçilen deprem kayıtları
ile hesaplanan istemler ile karşılaştırılmıştır. Bu amaçla halen yapı stokunun çoğunluğunu oluşturan
1975 Afet Yönetmeliği’ne göre tasarlanan 4 ve 7 katlı 28 betonarme binanın doğrusal ötesi modelleri oluşturularak
kapasite eğrileri elde edilmiştir. Bu yapılar tek serbestlik dereceli sisteme indirgenerek, ülkemizde yaşanmış
yıkıcı 18 ve literatürde sıklıkla kullanılan 10 yurt dışı depremin ivme kaydı kullanılarak zaman tanım
alanında doğrusal ötesi analiz (ZTAA) ile deplasman istemleri hesaplanmıştır. Çalışma sonucunda deplasman
katsayıları yöntemleri arasında ve ZTAA sonuçları arasında genel bir uyum gözlenirken kapasite spektrumu
yöntemiyle hesaplanan istemlerin oldukça yüksek olduğu gözlenmiştir. FEMA-356 ve FEMA-440 yöntemlerinde
dikkate alınan dayanım, rijitlik kaybı ve negatif akma sonrası rijitlik nedeniyle oluşacak olumsuzlukların
dikkate alındığı fakat AY-2006 da yer almadığı gözlenmiştir. Bu nedenle bu tür olumsuzlukların etkilerinin
arttığı durumlarla ilgili mühendis ve araştırmacıların bilgilendirilmesi gerektiği kanaatine varılmıştır
Orta Katlı Betonarme Yapıların Deprem Performansları
Conference PaperÖZ:
Ülkemiz son yirmi yılda çok büyük can kaybı ve maddi hasarlara sebep olan orta ve büyük şiddette depremlere
maruz kalmıştır. Ortaya çıkan hasarlı bina ve can kayıplarının sayısı göz önüne alındığında, dikkatler
çoğunluğunu 3–8 kat arası binaların oluşturduğu betonarme yapıların yetersiz performansları üzerinde yoğunlaşmıştır. Gözlenen hasarların başlıca nedenleri arasında, proje ile uygulama arasında beton kalitesi, donatı
miktarı ve detayları, taşıyıcı eleman boyut ve yerleşimleri açılarından önemli farklılıklar bulunması, zemin
katın işyeri amacıyla kullanılması sonucu oluşan yumuşak kat, zayıf kolon-kuvvetli kiriş, ağır kapalı çıkmalar,
Afet Bölgelerinde Yapılacak Yapılar Hakkında Yönetmelik (ABYYHY–75) öncesi inşa edilen yapıların
projelerinde gözönüne alınmış olan deprem yüklerinin az olması ve yetersiz konstrüktif detaylar ile zamana
ve çevresel şartlara bağlı oluşan hasarlar sayılabilir. Çalışmanın amacı, deprem riski yüksek olan ülkemiz yapı
stoğunun büyük bölümünü oluşturan orta yükseklikteki betonarme binaların deprem performanslarını Deprem
Bölgelerinde Yapılacak Binalar Hakkında Yönetmelik 2006’ya (DBYBHY–2006) göre değerlendirmektir.
Orta katlı yapıları temsil etmesi için 4 ve 7 katlı 14 adet bina seçilmiştir. Her bir yapı statik itme (artımsal
itme) analizine tabii tutulmuş, yapılara ait kapasite eğrileri hesaplanmıştır. DBYBHY-2006’ya göre, hesaplanan
kapasite eğrileri ışığında her bir yapıya ait deprem performansları belirlenmiştir.
Kamu Yapılarının Deprem Kapasitelerinin Değerlendirilmesi
Conference PaperÖZ:
Ülkemizde son otuz yılı aşkın bir dönemde bir bölümü büyük afet boyutunda olmak üzere toplam on beş yıkıcı
deprem yaşanmıştır. 13 Mart 1992 Erzincan ve 17 Ağustos 1999 Kocaeli başta olmak üzere ülkemizde yaşanan son
depremler, birçok kamu binamızın, içinde çalışan insanlara deprem bakımından yeterli can güvenliği sağlamadığını
göstermiştir. Son yıllarda kamu binalarının deprem risklerinin gözden geçirilerek deprem performanslarının artırılması için gerekli çalışmalar başlamıştır. Önceliklerin iyi belirlenerek, planlı ve ekonomik bir çalışmanın yapılabilmesi için her binanın tek tek incelenmesinden önce, yaygın kullanılan tip projeler üzerinde çalışmalar yapılarak proje eksiklikleri belirlenebilir. Bu çalışmada, doğrusal ötesi statik analiz ve performansa dayalı yapı tasarımı yaklaşımı ilkeleriyle, seçilecek tip projeli kamu binalarına ait performans değerlendirmesi yapılmış, projelerin zayıf noktaları belirlenmiş ve Deprem Bölgelerinde Yapılacak Binalar Hakkında Yönetmelik-2006’ın [DBYBHY, 2006] öngördüğü değerler ile kıyaslama yapılmıştır.
Kamu Yapılarında Beton Dayanımı ve Enine Donatının Performansa Etkisi (Effects of Concrete Strength and Transverse Reinforcement on the Performance of Public Buildings)
Conference PaperÖz –
Deprem sonrası muhtemel kullanımlar gözönüne alındıgında kamu binaları (hastane,
okul, telekomünikasyon, vb.), olası bir deprem felaketi sonrası ayakta kalması gereken
yapılardır. Özellikle son on yılda ülkemizin yasadıgı depremler, birçok kamu hizmet
binamızın bu gereksinimi saglamaktan uzak oldugu, hatta içinde çalısan insanlara yeteri
kadar can güvenligi saglamakta zorlandıgını göstermistir. Son yıllarda kamu yapılarının
deprem risklerinin gözden geçirilerek performanslarının artırılması için gerekli
çalısmalarının yapılması yönünde çabalar baslamıstır. Bu çalısmada, özellikle ülkemiz
kamu yapılarında en sık rastlanabilecek olumsuzluklardan olan düsük beton dayanımı ve
etriye sıklastırmasının yetersiz olusunun yapı davranısına etkisi üzerinde durulmustur.
Bunun için seçilen iki bloklu tip bir hastane binasının 2 farklı beton sınıfı ve 2 farklı
etriye aralıgının kombinasyonları göz önüne alınarak dogrusal ötesi modellemesi
yapılmıstır. Dogrusal ötesi statik itme analiz ve performansa dayalı yapı tasarımı
yaklasımı ile Afet Bölgelerinde Yapılacak Binalar Hakkında Yönetmelige eklenen yeni
bölümde öngörülen kriterler kullanılarak, farklı beton sınıfları ve etriye aralıkları için
performans degerlendirmesi yapılmıs, projelerin zayıf noktaları üzerinde durulmustur.
Türkiye’de Yaşanan Deprem Hasarları ve Yapı Stokunun Değerlendirilmesi (Earthquake Damages in Turkey and The Evaluation of Building Stock)
Conference PaperABSTRACT –
Over the past several decades, Turkey has been hit by several moderate to large devastating
earthquakes that resulted in significant loss of life and property. Remarkable number of
casualties and heavily damaged or collapsed buildings has emphasized inadequate seismic
performance of multistory reinforced concrete buildings, typically three to seven stories in
height. The aim of this study is to evaluate the seismic performance of the mid-rise reinforced
concrete buildings that are major part of building stock of our earthquake-prone country,
considering nonlinear behavior of reinforced concrete components as well as masonry infill
walls. A sample building set is designed according to 1975 Turkish Earthquake Code to reflect
existing possible construction practice; regular buildings and buildings with irregularities
such as soft story, heavy overhangs, short columns, and soft story with heavy overhangs.
Ductile and non-ductile details are taken into account by transverse reinforcement amount
(transverse reinforcement spacing of 100 mm and 200 mm). Capacity curves of investigated
building set are determined by pushover analyses conducted in two principal directions. The
inelastic dynamic characteristics are represented by equivalent single-degree-of-freedom (SDOF) systems. Their seismic displacement demands are determined using nonlinear
response history analysis under selected ground motions. Seismic performance evaluation is
carried out in accordance with recently published Turkish Earthquake Code (2007). Analytical
damage evaluation in this study has shown that the seismic effects of earthquakes experienced
in Turkey are significant and some of the earthquakes impose excessive displacement demands.
Therefore, considerable portion of existing building stock may not be safe enough in Turkey.
Also, it is observed that structural irregularities affect seismic performance of buildings.
Keywords: Reinforced concrete building stock, Buildings, Earthquake damages, Nonlinear static and
dynamic analysis.
Betonarme Elemanların Doğrusal Ötesi Davranışlarının Modellenmesi (Modelling Non-Linear Behavior of Reinforced Concrete Members)
Conference PaperABSTRACT –
Seismic risk of Turkey is high due to location and vulnerable building stock. Research and
advances in earthquake engineering need to be followed by civil engineers in practice to
reduce seismic risk that is a primary concern for Turkey. Nonlinear static and dynamic
procedures are well-known methods for the evaluation of existing structures. However,
modeling of structures for these methods is complex compared to linear procedures. The
deformation capacity of each element component needs to be determined using its material and
geometric characteristics for the nonlinear procedures. Repeating this process for several
hundred elements in a typical structure makes the use of these procedures almost impossible.
In this paper, a practical software for estimating deformation capacity of reinforced concrete
sections is introduced. The software includes moment-curvature analysis and determination of
moment-rotation capacity of a section. Program provides the use of 4 different concrete
models and 4 different plastic hinge lengths. Additionally, it has the feature of preparing input
data for commonly used nonlinear analysis programs in Turkey. The easy-to-use feature and
provided alternatives in modeling makes the program useful and an educational tool for
engineers in practice and students. Also, visual part of the program makes engineers and students to easily understand element and system behavior under earthquakes The proposed
program is considered as useful tool for civil engineers in practice because it helps to visualize
the behavior of concrete components and understanding of the new chapter in 2007 Turkish
Earthquake Code that is included to guide evaluation and retrofit of existing structures
Yumuşak Kat Davranışının Duvar Etkisi Dikkate Alınarak İncelenmesi (Investigations of Soft Story Behavior Considering Infill Effect)
Conference PaperABSTRACT –
Soft story irregularity is one of the main reasons of the building damage during earthquakes.
This irregularity is mentioned in almost all reconnaissance reports, and buildings having total
collapse at some stories, even without unbroken windows at others may be seen after
earthquakes. Soft story may arise not only because of sudden changes in structural system
properties (like height of the stories) but also due to abrupt changes in amount of infill walls
between stories which are usually not considered as a part of load bearing system. In this
study, soft story and effect of infills on this behavior are investigated using nonlinear static
analysis for mid-rise reinforced concrete buildings which are thought to be the most vulnerable
against earthquakes among existing building stock. Four and seven storey buildings are
designed per 1975 Turkish Earthquake Code to reflect existing building stock. Soft story
models of the reference buildings are obtained considering increased floor story height (4m
instead of 2.8), less amount of infill at floor story and both cases. Displacement capacities of
the reference and soft story models are determined at Immediate Occupancy, Life Safety and
Collapse Prevention performance levels according to 2007 Turkish Earthquake Code. Soft
story behavior due to change in story height and/or infill amount is evaluated in view of these
displacement capacities and structural behavior of models. All of the buildings are modeledwith two different transverse steel spacing as 10 and 20 cm to investigate the effect of
transverse steel amount on the behavior.
“Okul Binalarının Yeni Deprem Yönetmeliğine Göre Güçlendirilmesi (Evaluation of School Buildings Acording to Recent Turkish Earthquake Code)
Conference PaperABSTRACT-
Recent devastating earthquakes experienced in Turkey over the past several decades have
emphasized inadequate seismic performance of school buildings. This study evaluates seismic
capacity and performance of existing school buildings with the selected template designs
considering nonlinear behaviour of reinforced concrete components. Four template designs
were selected to represent major percentage of school buildings in medium-size cities located
in high seismic region of Turkey. Selection of template designed buildings and material
properties were based on field investigation on government owned school buildings in several
cities in western part of Turkey. Capacity curves of investigated buildings were determined by
pushover analyses conducted in two principal directions. Seismic capacity evaluation was
carried out in accordance with recently published Turkish Earthquake Code (2007. The effects
of material quality on seismic performance of school buildings were investigated. Also,
deficiencies and possible solutions to improve the capacity of school buildings are discussed.
Keywords: Nonlinear static analysis, School buildings, Performance based evaluation.
Performance of masonry structures during the 2009 L’Aquila (Italy) Earthquake
Conference PaperAbstract-
On 6 April 2009 an earthquake of magnitude 6.3 occurred in L’Aquila city, Italy. In the city center and surrounding villages many masonry and reinforced concrete (RC) buildings were heavily damaged or collapsed. After the earthquake, the inspection carried out in the region provided relevant results concerning the quality of the materials, method of construction and the performance of the structures. The region was initially inhabited in the 13th century and has many historic structures. The main structural materials are unreinforced masonry (URM) composed of rubble stone, brick, and hollow clay tile. Masonry units suffered the worst damage. Wood flooring systems and corrugated steel roofs are common in URM buildings. Moreover, unconfined gable walls, excessive wall thicknesses without connection with each other are among the most common deficiencies of poorly constructed masonry structures. These walls caused an increase in earthquake loads. The quality of the materials and the construction were not in accordance with the standards. On the other hand, several modern, non-ductile concrete frame buildings have collapsed. Poor concrete quality and poor reinforcement detailing caused damage in reinforced concrete structures. Furthermore, many structural deficiencies such as non-ductile detailing, strong beams-weak columns and were commonly observed. In this paper, reasons why the buildings were damaged in the 6 April 2009 earthquake in L’Aquila, Italy are given. Some suggestions are made to prevent such disasters in the future.
Performance Evaluation of a School Building in Turkey
Conference PaperAbstract –
A great part of existing RC structures built in Turkey have been designed without considering seismic-induced
actions and seismic criteria for strength and ductility design. In this context, after the recent devastating
earthquakes in Turkey, there has been a concerted effort to address the seismic vulnerability of existing public
buildings in Turkey. The need for the evaluation and strengthening of these public buildings have come into
focus following the enormous loss of lifes and property during the past earthquakes.
This study aims to assess the seismic performance evaluation of a typical school building in accordance with the
rules of Turkish Earthquake Code-2007. The performance analysis is carried out by using nonlinear static
analysis. The analytical solutions show that the intended performance level has not been satisfied for this
building and decided to retrofit the structural system. The proposed procedure is applied to the retrofitted system
and the obtained results are tabulated and discussed.
Typological Classification of Post-Byzantine Churches in Albania
Conference PaperABSTRACT –
Monumental historical structures are symbols of the cultural identity and continuity and they are the main part of the heritage and the human history. They should be preserved in their own settings with their original characteristics or with as minimum changes as possible. On the other hand, natural or man-made hazards cause a serious risk for the survival of them. In order to develop suitable restoration projects for these buildings without neglecting any of the cultural values, it is vital to determine the current conditions of these structures.
From this point of view, this paper aims to classify the churches in Albania built in post-Byzantine period based on the plan and spatial composition of these structures.
The typological classification helps to follow the development of post-byzantine architecture in time and space, the particularities that characterized this architecture in different periods and regions, the preference for certain types and forms in these periods and regions, their inter-relation, etc. The classification generally follows the criteria used in the study of byzantine architecture, which are mainly based on plan and spatial composition.
Evaluation of seismic analysis procedures for seismic actions: A Comparative study between Eurocode 8 and KTP-89
Conference PaperABSTRACT
The objective of this paper is to address the seismic design considerations for a case study building by using Eurocode 8 and the Albanian seismic code KTP-89 regulations. The parameter which is taken into account in this study is the design spectrum defined in each of the two codes. Basic differences exist between the two design spectra, such as the site coefficients, the spectral shape of the spectrum and also the integration by Eurocode 8 of the near and far field concept. The effects of these differences are studied by considering the different types of soils on a case study building. The obtained results on the base shear are compared and important differences between the two codes approach are discussed.
A new modeling approach in the pushover analysis of masonry structures
Conference PaperABSTRACT –
In this study, the pertinency of different numerical techniques for the analysis of masonry structures is investigated on a full-scale masonry specimen. Two approaches are taken into account. Namely, the nonlinear FEM modeling strategy, based on the concepts of idealized bilinear material behavior and line elements connected by special joints, is used in the version implemented in the commercial software 3Muri[2]. The second method is developed with programme SAP2000 which offers wide possibilities in finite element method models. Using specific modeling tools of SAP2000 is intended to simulate nonlinear behavior of masonry and global response of the structure.
An overview of such numerical methods, as well as a brief description of their specific theoretical aspects, is provided in order to allow easy comparison. A simple 2 story structure is modelled in both SAP2000 and 3Muri software. The key is the modeling with plane elements that have different characteristics in horizontal, vertical, and shear behaviour. Using this method is performed a pushover analysis and the results are compared to 3Muri software results. It is shown that the results prove a reliable modeling strategy by giving very similar output results. Having into consideration the fact that 3Muri software has been calibrated with experimental tests, the modeling approach with SAP2000 offers a satisfactory solution for masonry.
Seismic Performance Assessment of a Reinforced Concrete Building designed using the Albanian Seismic Code
Conference PaperAbstract –
A seismic performance evaluation was conducted for a reinforced concrete (RC)
frame structure representative of late 1990s construction in Albania. The case study
building is an eight-storey RC flat-slab office building designed for the Albanian
code requirements used in this region. The performance of the existing building is
compared to that of modern code designed building. The structural response is
evaluated using pushover analysis. The adequacy and the performance of the
buildings are checked and compared. The ATC-40 criteria were used to evaluate the
seismic performance of the case study buildings. The calculated values related to the
performance of the buildings indicate whether the response of the existing building
is sufficient and if rehabilitation is required.
Structural Analysis of post-Byzantine Churches: a case study for southern Albania
Conference PaperABSTRACT –
Hundreds of masonry churches have ben constructed in Albania during hundreds of
years. The majority of them exist at heir original ocation; a significant part of them are not in
use any more. In this context, Roman and post – Byzantine masonry churches atract the
world’s special atention to this region. It is necesary to cary out systematic studies to ases
an inventory and determine the state of masonry churches in Albania, to preserve them, to
strengthen their basic structural elements, the arch, vault and other constructive components
and soundly deliver them into the future. From this point of view, this study is aims to outline
the clasification of the churches built in post-Byzantine period based on the plan and spatial
compositon of these structures. Folowing this typological clasification, the church of the
“Monastery of Saint Nicholas” is selected as a case to investigate its structural performance.
The church of the Monastery of Saint Nicholas is a domed single-nave church dating back to
the 16th
-17th century. This church is situated inside a monastery complex and it is proclaimed
a monument of culture by Instiute of Monuments of Culture Albania.
Fragility based assessment of a school building in Turkey
Conference PaperABSTRACT-
This study focuses on, by means of a probabilstic aproach, the seismic safety evaluation
of a schol building in Turkey designed before the introduction of modern anti-seismic codes. A
typical schol building which was designed acording to the 1975 version of the Turkish
Earthquake Code is selected for the performance asesment. Inelastic pushover and time history
analyses are deployed under the efect of one hundred input ground motions. Fragilty curves are
generated for diferent concrete and detailng quality in terms of peak ground velocity. The
probabilstic seismic response and vulnerabilty of the schol are investigated by building
fragilty curves of the system and of its most vulnerable components. The results ilustrate the
significance of asesing the vulnerabilty of typical schol buildings under the efect of various
seismic scenarios and the ned for extending this study to cover other typical clases of schol
buildings in the region.
Seismic safety assessment of an unreinfroced masonry buildings in Albania
Conference PaperAbstract-
In Albania, hundreds of masonry buildings were constructed during the communist period which
covers 45 years until 1990s. Most of these buildings were designed without any seismic criterion. To mitigate
seismic risk in Albania, structural performance of masonry buildings have to be correctly evaluated. In this
paper, the efficiency of nonlinear-static procedures with a particular reference to the FEMA 440 method, for
estimating the seismic vulnerability of masonry buildings has been studied at local and global levels. For this
purpose, one template design most widely used in Albania has been selected. Selection of the material properties
and plan features of the case study structure has been based on archive study. By means of pushover analysis,
capacity curves of the investigated building were determined and quantitative estimate of earthquake damage is
performed for various earthquake levels. This evaluation has been carried out in compliance with Eurocode 8
requirements and safety assessment was carried out FEMA 440 guidelines
Reducing the Earthquake Effects on Buildings by Using New Technologies
JournalStructural Analysis of Domed Roof Systems in Architect Sinan’s Works
JournalABSTRACT: Domes in historical buildings by Architect Sinan were not only used alone as covering
spaces but they were also used as a various combinations of semi‐domes based on larger main and
flanking areas. On the other hand, Sinan, in the early years of his profession, improved a system based
on the mixture of perfectly developed main domes, pendentives, arches and semi‐domes. The behavior
of this monolithic system is quite complex. Therefore, to determine the structural behavior and the load
mechanisms of the monolithic systems formed main dome, arches, pendentives and semi‐domes is now
possible through current numerical methods based on computer‐aided analysis. In this study,
considering the superstructure of Sinan’s important mosques, Mihrimah Sultan/Edirnekapı,
Süleymaniye, Mihrimah Sultan/Üsküdar, Şehzade Mehmed mosques supported by square support
system, Karaahmetpaşa, Sokullu Mehmet Paşa/Kadırga mosques supported by hexagonal support
system, Sokullu Mehmet Paşa/Azapkapı and Selimiye mosques supported by octagonal support system
were statically analyzed under their dead loads by Structural Analysis Programme (SAP2000) based on
finite element methods. To avoid the confusion, which may come out in modeling and analyzing domed
roof systems, the models of all space coves have been established for the upper levels of arches resting
on columns. As a result, the structural behavior of main dome, arches, pendentives and semi‐domes was
determined and the structural behavior of each system was numerically revealed. Domes rested on
hexagonal and octagonal support systems are superior to other systems in terms of displacements and
stresses.
EFFECT OF CONFINED CONCRETE BEHAVIOUR ON REINFORCED CONCRETE SECTIONS AND SYSTEMS
JournalABSTRACT
In this study, the effects of confined concrete models on behavior of reinforced concrete structures are
investigated at member and system levels. The widely-accepted concrete models such as Modified Kent-Park,
Mander, and Saatcioglu-Razvi are considered. A four- storey structure was designed and detailed according to
1975 Turkish Earthquake Code to reflect a typical example of building stock in Turkey. The building was
considered to be in Earthquake Zone 1 and on Z3 Soil Type. Nonlinear behavior of the building frame was
modeled by considering the inelastic section behaviour of each beam and column elements for different concrete
class and transverse reinforcement spacing. The models were subjected to pushover analysis. The differences of
confined concrete models were investigated for both reinforced concrete member and system levels. At the end
of analyses, it was observed that although there were some differences at the section level, the effects of
confined concrete models were negligible at the system level.
Seismic Evaluation Of Existing Mid-Rise Reinforced Concrete Buildings According To Specification For Building Structures To Be Built In Disaster Area
JournalAbstract-
Over the past several decades, Turkey has been hit by devastating earthquakes and remarkable number of
reinforced concrete buildings has been damaged in the high seismicity regions of our country. The aim of this
study is to evaluate the seismic performance of the mid-rise reinforced concrete buildings that are major part of
building stock of our earthquake-prone country, according to recent Turkish Earthquake Code. 4- and 7-story
buildings were selected to represent mid-rise building stock. After determining the structural parameters, each
building was subjected to pushover analysis and the capacity curves were obtained. Earthquake performance of
each building was determined in the light of their capacity curves according to the recent Turkish Earthquake
Code.
Seismic Assessment of Existing R.C. Public Buildings in Turkey - An Overview with a Case Study
JournalAbstract –
The recent devastating earthquakes have exposed the vulnerability of the existing
public buildings in Turkey. A great part of these reinforced concrete buildings has
been designed considering earlier codes when seismic loads were not required or
the design was at lower level of seismic loads of what is currently specified. In
Turkey, template designs developed by the General Directorate of Construction
Affairs are used for many of the buildings intended for governmental services
(administrative centers, hospitals, schools, etc.) as prevalent practice to save on
architectural fees and ensure quality control. The need for evaluating the seismic
adequacy of these public buildings has come into focus following the enormous
loss of life and property during the recent earthquakes.
This paper aims to evaluate the seismic performance of a public building with the
selected template design in Turkey considering the nonlinear behavior of
reinforced concrete members. For the building addressed in this paper, material
properties are based on field investigation on government public buildings in
western part of Turkey. Seismic performance evaluation will be carried out in
accordance with the recently published Turkish Earthquake Code-2007 that has
many similarities with FEMA 356 guidelines.
Capacity curves of investigated building will be determined by nonlinear static
analysis. The effects of material quality on seismic performance of this public
building will be investigated. In conclusion, different possible deficiencies and
solutions to improve template design building will be discussed. This study gives an
in depth sight into to the rehabilitation of public buildings in Turkey
Re-evaluation of building damages during recent earthquakes in Turkey
JournalAbstract
Over the past two decades Turkey has been hit by several moderate to large earthquakes that resulted in significant loss of life and property. A remarkable number of casualties and heavily damaged or collapsed buildings has emphasized inadequate seismic performance of multistory reinforced concrete buildings, typically three to seven stories in height. This study aims to evaluate seismic performance of the most common reinforced concrete building stock in Turkey considering nonlinear behavior of the components. A sample building set is selected to reflect existing construction practice; regular buildings and buildings with irregularities such as soft story, heavy overhangs, short columns, and soft story with heavy overhangs. Ductile and non-ductile details are taken into account by transverse reinforcement amount. Capacity curves of the investigated building set are determined by pushover analyses conducted in two principal directions. The inelastic dynamic characteristics are represented by equivalent single-degree-of-freedom (SDOF) systems. Their seismic displacement demands are determined using nonlinear response history analysis under selected ground motions. Seismic performance evaluation is carried out in accordance with the recently published Turkish Earthquake Code (2006) that has similarities with FEMA-356 guidelines. Analytical damage evaluation in this study has shown that the seismic effects of earthquakes experienced in Turkey are significant and some of the earthquakes impose excessive displacement demands. Therefore, a considerable portion of existing building stock may not be safe enough in Turkey or similar countries. Also, it is observed that structural irregularities affect seismic performance of buildings. Short columns and soft story with heavy overhangs have the most negative effect.
Performance of Mid-Rise Reinforced Concrete Buildings During Recent Earthquakes in Turkey
JournalAbstract
Over the past two decades Turkey has been hit by several moderate to large earthquakesthat resulted in significant loss of life and property. Remarkable number of casualties andheavily damaged or collapsed buildings has emphasized inadequate seismic performance ofmultistory reinforced concrete buildings, typically three to eight stories in height. The aimof this study is to evaluate the seismic performance of the mid-rise reinforced concrete buildings which are major part of building stock. In performance evaluation, destructiveearthquakes over the past two decades have been taken into consideration. Fourteen 4- and7-story buildings are selected to reflect existing construction practice, including structural irregularities. Capacity curve of each building was obtained by pushover analysis. Then,their seismic displacement demands were determined using nonlinear time history analysisunder selected ground motions. The inelastic dynamic characteristics were represented byequivalent single-degree-of-freedom systems. Seismic performance evaluation is carriedout per recently published 2007 Turkish Earthquake Code.
Seismic Performance Evaluation of School Buildings in Turkey
JournalAbstract
This study evaluates seismic performance of the school buildings with the selected template designs in Turkey considering nonlinear behavior of reinforced concrete components. Six school buildings with template designs were selected to represent major percentage of school buildings in medium-size cities located in high seismic region of Turkey. Selection of template designed buildings and material properties were based on field investigation on government owned school buildings in several cities in western part of Turkey. Capacity curves of investigated buildings were determined by pushover analyses conducted in two principal directions. The inelastic dynamic characteristics were represented by equivalent single-degree-of freedom (SDOF) systems and their seismic displacement demands were calculated under selected ground motions. Seismic performance evaluation was carried out in accordance with recently published Turkish Earthquake Code that has similarities with FEMA-356 guidelines. Reasons of building damages in past earthquakes are examined using the results of performance assessment of investigated buildings. The effects of material quality on seismic performance of school buildings were investigated. The detailed examination
of capacity curves and performance evaluation identified deficiencies and possible solutions for template designs.
Seismic Capacity Evaluation of School Buildings in Turkey
JournalAbstract
This study evaluates the seismic capacity of school buildings with the selected template designs constructed per pre-modern code in Turkey, considering non-linear behavior of reinforced concrete components. Capacity curves of the investigated buildings were determined by pushover analyses conducted in two principal directions. Seismic capacity evaluation was carried out in accordance with the recently published Turkish Earthquake Code (2007) that has similarities with FEMA-356 guidelines. Based on capacity curves of school buildings, it was found that the effect of material quality and detailing on seismic capacity is especially apparent for buildings with no or a limited number of shear walls. Buildings with a certain number of shear walls are less affected by low material quality and detailing, emphasizing the importance of shear walls, especially in countries where construction with poor detailing is a common problem. The outcome of the study indicates that the existing school buildings constructed per the pre-modern code far from satisfying the expected performance objectives of the recent code requirements, suggesting that urgent planning and response need to be put in action.
Abstract
On 6 April 2009 an earthquake of magnitude 6.3 occurred in L’Aquila city, Italy. In the city center and surrounding villages many masonry and reinforced concrete (RC) buildings were heavily damaged or collapsed. After the earthquake, the inspection carried out in the region provided relevant results concerning the quality of the materials, method of construction and the performance of the structures. The region was initially inhabited in the 13th century and has many historic structures. The main structural materials
are unreinforced masonry (URM) composed of rubble stone, brick, and hollow clay tile. Masonry units suffered the worst damage. Wood flooring systems and corrugated steel roofs are common in URM buildings. Moreover, unconfined gable walls, excessive wall thicknesses without connection with each other are among the most common deficiencies of poorly constructed masonry structures. These walls caused an increase in earthquake loads. The quality of the materials and the construction were not in accordance with the
standards. On the other hand, several modern, non-ductile concrete frame buildings have collapsed. Poor concrete quality and poor reinforcement detailing caused damage in reinforced concrete structures. Furthermore, many structural deficiencies such as non-ductile detailing, strong beams-weak columns and were commonly observed. In this paper, reasons why the buildings were damaged in the 6 April 2009 earthquake in L’Aquila, Italy are given. Some suggestions are made to prevent such disasters in the future.
Seismic Performance Evaluation of Unreinforced Masonry School Buildings in Turkey
JournalAbstract
In this study a seismic performance assessment of school buildings, which have been built in accordance with template unreinforced masonry school projects in Turkey, has been conducted. For this purpose, the most widely used three template projects have been selected. The seismic performances of these buildings have been evaluated for various earthquake levels. This evaluation has been carried out in compliance with the Turkish earthquake code entered into force in 2007. The effects of material strength and plan features on the performance of masonry school structures have been investigated within the scope of this study. It has been concluded that school buildings with template design are far from satisfying the required performance criteria. For spectral acceleration of 0.80 g, which is expected in a 475 year period in the seismic Zone 1, the average exceedance ratio for life safety performance limit is more than 80% considering different material strengths. Upon evaluation of the results a building capacity index is proposed for rapid seismic assessment of masonry school buildings.
Seismic capacity evaluation of unreinforced masonry residential buildings in Albania
JournalAbstract
This study evaluates seismic capacity of the unreinforced masonry buildings with the selected template designs constructed per pre-modern code in Albania considering nonlinear behaviour of masonry. Three residential buildings with template designs were selected to represent an important percentage of residential buildings in medium-size cities located in seismic regions of Albania. Selection of template designed buildings and material properties were based on archive and site survey in several cities of Albania. Capacity curves of investigated buildings were determined by pushover analyses conducted in two principal directions. The seismic performances of these buildings have been determined for various earthquake levels. Seismic capacity evaluation was carried out in accordance with FEMA (Federal Emergency Management Agency) 440 guidelines. Reasons for building damages in past earthquakes are examined using the results of capacity assessment of investigated buildings. It is concluded that of the residential buildings with the template design, with the exception of one, are far from satisfying required performance criteria. Furthermore, deficiencies and possible solutions to improve the capacity of investigated buildings are discussed.
Fragility-based assessment of public buildings in Turkey
JournalAbstract
Public buildings which are mostly built of reinforced concrete with template designs constitute a great part of the vulnerable public building stock in Turkey as well as in several other countries prone to earthquakes. This study focuses on seismic fragility assessment of reinforced concrete public buildings with representative template designs, which have been designed according to the 1975 version of the Turkish seismic design code. Lateral stiffness, strength and displacement capacities of the selected template designs are determined by nonlinear static analyses in two principal directions. The inelastic dynamic characteristics of the template designs investigated are represented by equivalent single degree of freedom systems and their seismic deformation demands are calculated using a set of 100 strong ground motion records. Peak ground velocity is selected as the measure of seismic intensity because it has a good correlation with maximum inelastic displacements. Based on assessed capacities and demands, fragility curves are derived separately for each template designs. Buildings are grouped according to the number of storeys. The results revealed that the effect of concrete and detailing quality on IO performance level is more limited and less critical as the ground motion intensity increases. On the other hand, the probability of exceedence for LS and CP are closer to each other for each group of buildings. Finally, using constructed fragility curves, collapse probabilities of existing public buildings were estimated according to PGV values. The results are evaluated in terms of concrete quality and transverse reinforcement detailing.