Nakipoğlu, Abdulhamit
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Nakipoğlu, A.
Nakipoglu, A.
Nakipoglu, Abdulhamit
Nakipoglu, A.
Nakipoglu, Abdulhamit
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anakipoglu@ktun.edu.tr
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02.02. Department of Civil Engineering
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| Journal | Count |
|---|---|
| Advanced Engineering Science (AES) | 1 |
| Bulletin of Earthquake Engineering | 1 |
| Konya mühendislik bilimleri dergisi (Online) | 1 |
| MATERIALS TESTING | 1 |
| Niğde Ömer Halisdemir Üniversitesi Mühendislik Bilimleri Dergisi | 1 |
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Article Citation - WoS: 1Citation - Scopus: 1Strengthening of Reinforced Concrete Buildings With Soft Story Irregularity(CARL HANSER VERLAG, 2019) Döndüren, Mahmud Sami; Nakipoğlu, AbdulhamitTurkey is one of the most earthquake-prone countries in the world. The studies on the damaged buildings with reinforced concrete structural systems, especially done after the 1999 Golcuk earthquake and other earthquakes in the past, showed that the negative effects of the structural irregularities in the buildings come to light through the impact of earthquake load. They also revealed that the regularity of structural systems is one of the main principles in the design of earthquake resistant reinforced concrete structural systems. In this study, two-story singlespan 1/3 scaled reinforced concrete test specimens having soft story irregularity (interstory stiffness irregularity) and insufficient earthquake resistance were tested by applying different strengthening methods. The purpose of strengthening applications is to eliminate the adverse effects of the soft story irregularity. Reversed-cyclic lateral load was applied on the test specimens to simulate the earthquake effect. While the upper stories in all the test specimens had infill walls, the lower stories had been strengthened using different types of steel bracings. The first frame was strengthened with K-type shaped (<>), the second one with straight. V-type (V) and the third with turned sideways V-type (>) steel diagonal elements. As a reference to these three strengthened frames, the following two frames, which were taken from another study, were used; a frame with both stories having infill walls and a frame with infill walls on the upper story, which is empty on the lower story. As a result of the study, load and displacement histories, hysteresis and envelope curves and energy dissipation graphs of these three strengthened reinforced concrete frames were obtained. Furthermore, all the experimental results, obtained graphs and the data from the reference frames were compared and interpreted. The results show that the frame strengthened with K-type steel bracings is the best solution to reduce the effect of soft story irregularity.Book Kahramanmaraş Earthquakes Hatay (türkiye)(Eğitim Yayınevi, 2023) Kamanlı, Mehmet; Döndüren, Mahmud Sami; Çöğürcü, Mustafa Tolga; Kekeç, Bilgehan; Ünal, Alptuğ; Saydan, Murat; Cengiz, Salih; Lorasokkay, Mehmet Ali; Özdemir, Sıtkı Alper; Solak, Abdulkadir; Nakipoğlu, Abdulhamit; Torun, SuatArticle Effect of Arrangement of Masonry Infill Walls, Shear Walls and Steel Bracings on the Story Drift and Stiffness Irregularity(2023) Al-hagri Mohammed Gamal; Nakipoğlu Abdulhamit; Döndüren Mahmud SamiIrregularities in structures, such as soft story irregularity, might make them vulnerable under lateral forces such as earthquake. One solution to this problem is a suitable use of infill members. In this study, the effect of masonry infill walls, shear walls and steel bracings on the soft story irregularity and story drift of a 10-story building is evaluated. The building has its first two stories not infilled, and the remaining stories fully infilled with masonry infill walls. Fourteen models of different infill situation divided into three groups were studied. In the first infill group, the 1stand 2ndstories were fully infilled with masonry infill walls, shear walls and steel bracings. In the second infill group, infill members were used in the center of the building. In the third group, infill members were placed in some portions of the exterior surface of the building. Moreover, two more models were developed to overcome the excess of the permissible values of partially infilled models using shear walls by changing the thickness of the shear walls. The models were analyzed using ETABS analyzing software. The results showed that arrangement of infill members has remarkable effect on the soft story irregularity and story drift. They also showed that symmetry in the elevation of the building has great impact on the performance of the building against stiffness irregularity and lateral displacement ofthe structure. The most applicable solution for the stiffness irregularity and story drift problems in the studied building is partially infilling the exterior surfaces with steel bracings or shear walls. With these infilling methods, the interior parts of the first two stories will be empty and can be used for different purposes since the infilling is only applied in the exterior surfaces of the building.Article Citation - WoS: 4Citation - Scopus: 4Damage Analysis of Golyazi Apartments Building Failed Under Axial Loads: a Case Study in Konya, Turkey(ELSEVIER SCIENCE INC, 2021) Nakipoğlu, Abdulhamit; Ünal, Alptuğ; Kamanlı, MehmetThis study is in the characteristics of a case study. In this study, damage analysis has been made to the Golyazi Apartments Block A building and the causes of the damages were investigated. The building is located in Konya/ Turkey. It has some damaged vertical load bearing elements as a result of various effects. The damage was first detected by the residents in September 2018. Creep and axial load analyzes were carried out in the building through ETABS and ANSYS structural analysis programs and crack/damage checks were made analytically for the existing damage situation and for new damages that might occur. At the end of the study, it has been observed in some of the columns in the humid basement of the building that load bearing capacities were exceeded due to creep, axial compressive loads and corrosion effects and severe damages occurred. In addition, ANSYS analysis results coincide with existing building damage. Although no damage occurred in some of the columns of the structure, damage was observed in the same columns in the ANSYS model. This situation might predict the future damage in the building that can happen. Finally, some measures that can be taken as a result of the identified damage situation are presented.Article Effect of Column Cross Section and Concrete Compressive Strength on the Resistance of Rc Columns Subjected To Axial Loads and Loads Created by Creep(2022) Nakipoğlu, Abdulhamit; Al-Hagri, Mohammed Gamal; Döndüren, Mahmud SamiReinforced concrete buildings that are not properly designed, constructed, or supervised, might not have the resistance to bear even their own weight. When the effects of deformation in the concrete over time are added to the loads, great damages and even collapses can be seen. In this study, the performance of reinforced concrete buildings under axial loads was investigated. The effect of creep in concrete over time was also evaluated. Creep deformation has been integrated into the analysis with a simple method. A total number of 20 8-storey reinforced concrete frame buildings were modeled via ETABS. In each model, only column dimensions and concrete compressive strengths have been changed. The models were analyzed under the combined effect of axial loads and creep. As a result, the effect of concrete compressive strength and column dimensions on collapse in reinforced concrete buildings under the mentioned effects was examined. The results showed that column dimensions should be much high to prevent collapse when low strength concrete is used in buildings. In addition, a formula that can be used to determine the parameters of concrete quality and column cross-sectional areas required against collapse is proposed for the preliminary design of similar types of buildings.Doctoral Thesis Experimental Investigation of Effect of Damage, Repair and Strengthening on Dynamic Behavior in R C Buildings(2024) Nakipoğlu, Abdulhamit; Döndüren, Mahmud SamiBütün yapılar ortam şartlarından dolayı her an az veya çok şiddette titreşime maruz kalırlar. Titreşimin kaynağı, yapılarda büyük hasarlar oluşturabilen zamana bağlı dinamik yüklerdir. Sistemlerde meydana gelen titreşim tepkisini zamandan bağımsız statik analiz yöntemleriyle çözümlemek çok gerçekçi olmayıp yapıların davranışını da tam manasıyla yansıtamamaktadır. Dinamik yüklemeye maruz bir sistemde oluşacak tepkiler statik yüklemeye maruz sistemlere kıyasla daha büyük olmaktadır. Yapılarda daha büyük iç kuvvetler ve yer değiştirmeler meydana gelmektedir. Tüm bunlar göz önünde bulundurulduğunda yapıların tasarım aşamasında dinamik yüklerin rolü çok büyüktür. Bu sebeplerden dolayı, yapıların dinamik etkiler altındaki davranışını incelemek ve bu incelemeleri dinamik çözüm yöntemleri vasıtasıyla yapmak oldukça önemlidir. Deprem laboratuvarı yakıştırması dahi yapılan ülkemiz için bir dinamik yükten bahsedeceksek bu şüphesiz deprem yükü olacaktır. Türkiye her yıl yaklaşık 30 bin depremi tecrübe etmektedir. Bu depremlerin bir kısmı yapılara hasar verecek seviyede olmaktadır. Burada elbette yapının durumu ve performansı da belirleyicidir. Deprem etkisiyle hasar almış olan yapılar çoğu zaman güçlendirme/onarım işlemleri henüz başlamamışken artçı veya yeni ana sarsıntıların etkisinde kalmaktadır. Dolayısıyla, halihazırda belirli bir seviyede hasarlı olan bir yapıda deprem direnci azalmış olacağından yeni sarsıntılar yapının göçmesine sebep olabilmektedir. Daha önceden de olduğu gibi çok yakın zamanda 6 Şubat 2023 Kahramanmaraş depremlerinde de maalesef bu durum milletimiz tarafından acı bir şekilde tecrübe edilmiştir. Bu çalışmada, betonarme binalarda deprem neticesinde oluşan hasarlar ile uygulanan onarım ve güçlendirmelerin dinamik davranış üzerindeki etkileri araştırılmıştır. Çalışmada, laboratuvar ortamında üretilmiş olan 3 adet 1/3 ölçeğindeki 3 boyutlu 2 katlı-tek açıklıklı betonarme çerçeve numunesinin sarsma tablasında zorlanmış titreşim deneyleri yapılmıştır. Numuneler hasarsız, hasarlı, onarılmış ve güçlendirilmiş durumlarında test edilmiştir. Hasarlı durumda numunelerin birleşim bölgeleri zayıflatılmıştır. Hasarlı bölgeler devamında tamir harcı kullanılarak onarılmıştır. Güçlendirme aşamasında sistemsel bazda teknikler kullanılmıştır. Bu aşamada, düzlem içi betonarme perdeler vasıtasıyla güçlendirme, X şeklinde çelik çaprazlarla güçlendirme yöntemleri kullanılmıştır. Ayrıca yine bu aşamada, dolgu duvarların dinamik davranışa katkısını görmek maksadıyla bir de dolgu duvarlarla iyileştirme yöntemi uygulanmıştır. Zorlayıcı yük olarak, 0,19 g, 0,36 g, 0,46 g ve 0,54 g en büyük yer ivmesi değerlerine sahip olan 4 farklı şiddette yapay yer hareketi kullanılmıştır. Numunelerin farklı durumlarında bu 4 farklı şiddetteki dinamik yük altında toplam 200'den fazla zorlanmış titreşim deneyi yapılmıştır. v Deneylerde ivmeölçerler vasıtasıyla zamana bağlı ivme verileri ve potansiyometrik cetveller vasıtasıyla zamana bağlı deplasman verileri kaydedilmiştir. Bu veriler üzerinden geleneksel deneysel modal analiz yöntemiyle dinamik parametreler (doğal titreşim frekansları, doğa titreşim periyotları, doğal sönüm oranları, mod şekilleri) belirlenmiş ve ivme, deplasman tepki spektrumları oluşturulmuştur. Ayrıca, zaman tanım alanında; kat deplasmanları, taban kesme kuvvetleri, taban devrilme momentleri ve taban kesme kuvveti-tepe deplasmanı, taban devrilme momenti-tepe deplasmanı oranı histerezis eğrileri, yanal ötelenme rijitlikleri elde edilmiştir. Diğer bir taraftan, numunelerde aynı durum, yükleme ve şartlar altında sonlu elemanlar yöntemi mantığıyla çalışan ETABS yapısal analiz programı kullanılarak zaman tanım alanında hesap yöntemiyle nümerik analizler de yapılmıştır. Deneysel ve nümerik olarak elde edilen bütün parametre ve grafikler ışığında hasar, onarım ve güçlendirmelerin dinamik davranışa etkileri irdelenmiştir. Sonuçta, hasarlı durumda yanal ötelenme rijitliğinin ciddi oranda azaldığı ve deplasman taleplerinin oldukça arttığı, güçlendirmelerin etkisiyle büyük miktarda rijitlik kazanımı meydana gelerek aynı yükler altında kaydedilen deplasman değerlerinin çok azaldığı görülmüştür. Benzer şekilde, 1. doğal titreşim frekanslarında, hasarlı durumdan güçlendirilmiş duruma geçildiğinde değerlerin ortalama %70 oranında arttığı hesaplanmıştır. Genel olarak, düzlem içi betonarme perdelerle yapılan güçlendirme sonucunda her yönden en iyi performanslara erişilmiştir. Ayrıca, nümerik analiz sonuçları da deneysel sonuçlarla büyük oranda uyumlu çıkmıştır.Article Experimental and Numerical Investigation on the Effect of Infill Walls on Dynamic Behavior in Rc Structures: Shake Table Tests(Konya Teknik Univ, 2025) Dondüren, Mahmud Samı; Nakipoğlu, AbdulhamitInfill walls have many positive and negative effects on reinforced concrete (RC) buildings under the effect of earthquakes, but these are often not taken into consideration sufficiently. The contribution of walls to stability and stiffness in particular is considerable. In the negative sense, due to various reasons, incorrect/incomplete use of infill walls can cause extremely fatal irregularities such as short columns and soft stories. In this study, the effect of infill walls on the dynamic behavior of reinforced concrete buildings was examined. The study was conducted on a dynamic basis in order to approach the behavior under the effect of earthquakes in a more realistic way. For this purpose, a 1/3 scale 2-storey single-span reinforced concrete frame was produced for the experiments. Forced vibration tests were carried out on the shake table in the reference state (bare frame) and in the infill-walled state. The sample was subjected to an artificial ground motion with a peak ground acceleration (PGA) value of 0.54 g in both states. Experimental modal analysis, load-displacement analysis, and numerical analysis on ETABS structural analysis software were done. As a result, it was observed that the infill walls significantly enhanced the stiffness, leading to a considerable reduction in displacement values. Calculations showed that the natural frequencies increased by approximately 5-10%, while the global damping ratio decreased by about 20%.Conference Object Betonarme Yapılarda Hasar, Onarım ve Güçlendirmelerin Dinamik Davranışa Etkisinin Deneysel Olarak İncelenmesi(2022) Döndüren, Mahmud Sami; Nakipoğlu, AbdulhamitBu çalışmada, deprem hasarına maruz kalmış betonarme yapıların hasar, onarım ve güçlendirme durumlarının yapıların dinamik davranışına ne ölçüde etki ettiği araştırılacak ve uygulanan iyileştirmelerin performansları irdelenecektir. Bu amaçla 1/3 ölçekli 2 katlı ve tek açıklı 3 boyutlu 3 adet betonarme çerçevede hasarsız durum, birleşim bölgelerinden hasarlı durum, onarılmış durum ve dolgu duvarlarla, düzleme içi ve düzleme bitişik perde duvarlarla ve X çelik çaprazlarla güçlendirilmiş durumlar test edilecek ve araştırılacaktır. Numunelere sarsma tablası ile zorlanmış titreşime maruz bırakılacaktır. Numunelere her durumda aynı şiddette Kobe depreminin 1/2 ivme ölçekli simülasyonu uygulanacaktır. Titreşim deneyleri esnasında numunelerde kat hizalarından ivme ve deplasman talepleri ölçülecektir. Geleneksel deneysel modal analiz ile frekans davranış fonksiyonları üzerinden doğal titreşim frekansları, sönüm oranları ve mod şekilleri belirlenecektir. Ayrıca yük-deplasman histerezis eğrileri, zarf eğrileri, enerji tüketimi ve rijitlik değerleri incelenecektir. Sonuçta yapılarda her farklı durumda dinamik davranış elde edilecek, hasarın, onarım ve güçlendirmelerin davranışa etkisi karşılaştırılarak yorumlanacaktır.Article Shake Table Experiments and Numerical Simulation on the Effects of Damage and Strengthening on Dynamic Behavior of RC Frames(Springer, 2025) Nakipoglu, Abdulhamit; Donduren, Mahmud SamiThis study presents an investigation on the effects of damage and strengthening on the dynamic behavior of buildings. Forced vibration tests were carried out on the shake table of two 1/3 scale, 3D, 2-story, single-span reinforced concrete frame specimens produced in laboratory. The damage was created by weakening the joint areas. Then the damaged zones were repaired and strengthening methods using in-plane reinforced concrete shear walls and X-shaped steel diagonal bracings were applied. The aim here is to perform a dynamic-based performance evaluation of these two commonly used global systemic strengthening techniques in practice. A total of more than 105 forced vibration experiments were carried out under 4 different intensities of dynamic load in different conditions of the specimens. Dynamic parameters were determined with the experimental modal analysis method. Moreover, story displacements time history, base shears time history, base shear-top displacement hysteresis curves, and lateral translational stiffnesses were obtained. In addition, numerical analyses using ETABS finite element software were also conducted. As a result, it was observed that the damage reduced the lateral translational stiffnesses by about 50%, steel bracings increased the stiffness in the damaged condition by 147% and RC shear walls increased it by 381%. On average, the 1st natural frequency decreased by 36.5% in the damaged conditions, increased by 83% in the strengthened conditions compared to the damaged conditions. Strengthening of the members tends to limit the soft story behavior. In general, although its application is difficult, the best performance in all studied parameters was obtained from the specimen strengthened with in-plane reinforced concrete shear walls.
