Papers by Kürşat Alyamaç
Earthquakes and Structures, 2015
Waste and Supplementary Cementitious Materials in Concrete
Fırat Üniversitesi Mühendislik Bilimleri Dergisi
e-Journal of New World Sciences Academy
Traditional concretes, which have a lot of usage in practice, have huge unit weights. Lightweight... more Traditional concretes, which have a lot of usage in practice, have huge unit weights. Lightweight concretes have less weight than traditional concretes. By using lightweight concrete in the reinforced concrete structures, the total amount of concrete to be used in the buildings can be reduced, the buildings can be lightened, and the total weight of the building can be reduced. High-performance concrete is needed to build permanent and long-lasting structures. The aim of this study is to assess comprehensively the previous studies on highstrength lightweight concrete and to present a different perspective for this subject. In the present study, the mechanical properties of high-performance lightweight concretes with different mixing ratios were examined. Compressive strengths of traditional concretes and lightweight concretes were compared. In addition, the compressive strengths of the concrete specimens produced in the building materials laboratory were tried to be estimated by the statistical analysis. A good fitting was obtained between the experimental and the predicted results.
ZET Beton dünyada en çok kullan yap malzemesidir. Betonun davran birçok yönden incelenmektedir. B... more ZET Beton dünyada en çok kullan yap malzemesidir. Betonun davran birçok yönden incelenmektedir. Bu çal gelece beton yap tasar yöntemi olarak görülen Mekani Prensiplerinden Parametreli Model kullan Bu yakla betonda kritik gerilme çarpan s Ic K ve kritik çatlak ucu aç CTOD c gibi iki parametre ile modellemektedir. Farkl çimentolarla, çimento miktar ve çökme miktar e olan kar elde edilmi ve bunlarla çentikli beton kiri ve standart küp numuneler yap Olu her bir seriye ayr ayr 3, 7 ve 28 gün su kürü uygulanm 28 gün sonunda küp numunelerden betonlar bas dayan belirlenmi ve daha sonra kiri numuneler, üç noktal e deneylerine tabi tutularak, k yükleri hesaplanm Elde edilen bu de k mekani metotlar Parametreli Model ile analiz edilerek, betonlar k parametreleri hesaplanm 28 gün boyunca su kürü uygulanan betonlar en iyi k parametrelerine sahip oldu görülmü Ayr dayan yüksek olan çimento ile üretilen betonlar k parametrelerinin daha iyi oldu tespit edilmi ABSTRACT Concrete is the most commonly us...
Çatlamış bir yapı, en iyi kırılma mekaniği prensipleri kullanarak analiz edilebilir. Kırılma meka... more Çatlamış bir yapı, en iyi kırılma mekaniği prensipleri kullanarak analiz edilebilir. Kırılma mekaniğine göre herhangi bir yapıyı analiz edebilmek için ise, ilk önce malzemenin kırılma parametrelerinin hesaplanması gerekir. Betonda, çimento fazı çatlakların gelişip yayıldığı fazdır. Bu özelliğinden dolayı betonun kırılma mekaniği açısından önemlidir. Sunulan çalışmada, Türkiye’de üretilen çimentoların kırılma parametrelerini tayin etmek için, 8 farklı çimento tipi için, başlangıç çentik boyları = 4, 6, 10 mm olan ve her bir çentik boyundan iki adet olmak üzere toplam 6 adet numune üretilmiştir. Dökülen numuneler, standart olarak 28 gün boyunda 20 oC de bekletilmiştir. Numuneler, mesnet açıklığı 10 cm olmak üzere üç noktalı eğilme deneylerine tabi tutularak kırılma yükleri hesaplanmıştır. Daha sonra kırılan her bir numunenin basınç mukavemetleri tayin edilmiştir. Kırılma yükleri, İki Parametreli Model ile analiz edilerek çimentoların kırılma parametreleri ve CTODc hesaplanmıştır. Anah...
The behaviors of the structures of the rural area during the Basyurt-Karakocan (Elazig) Earthquak... more The behaviors of the structures of the rural area during the Basyurt-Karakocan (Elazig) Earthquake, which occurred on March 8th of 2010, were investigated with this study. To conduct the evaluation of damages, the structures were investigated on the field right after the earthquake and the damages were recorded. The observed damages were interpreted with regard to the principles of the all previously effectuated regulations in order to take the limitations defined at the year of the construction into the consideration. It was observed that the majority of the structures, which were constructed by using adobe, brick, stone, or wood, were far-off the principles of regulations. It is hoped that the presented study will activate the assessment and the retrofit of the structures (having similar characteristics) that were constructed in similar earthquake zones.
Fracture parameters are among the most important characteristics of hardened concrete. In this st... more Fracture parameters are among the most important characteristics of hardened concrete. In this study, SCC was investigated via the two-parameter fracture model (peak-load method) which needs two fracture parameters namely: the critical stress intensity factor s IC K and the critical crack mouth opening displacement CTOD c to characterize failure of concrete structures. In SCC mix, different marble powders were used as powder materials. Marble powder is a new material for concrete. Marble powder is a limestone origin waste material. Samples 150x150x150 mm and 150x150x450 mm in size were produced. It is known that there is a close relation between concrete compressive strength and fracture parameters. Critical stress intensity factor s IC K and critical crack tip opening displacement CTOD c , fracture parameters were determined. Consequently, it was observed that concrete compressive strength and powder admixture are effective on fracture parameters of SCC.
Indian Journal of Engineering and Materials Sciences
The aim of this study is to predict formulas based on the Abrams' Law between fracture parame... more The aim of this study is to predict formulas based on the Abrams' Law between fracture parameters of concrete and w/c. Therefore, a series of three-point bend test on specimens were performed. The beams were made from mixes with water/cement ratios varying in the range of 0.34-0.85. The fracture parameters for each mix were calculated according to a popular fracture mechanics approach — two-parameter model. The present experimental data indicate that the fracture parameters of two-parameter model are inversely proportional to w/c ratios. In conclusion, the present test results are in agreement with the Abrams' Law.
zet: Bu çalışmada, planda A3 türü yapısal düzensizliklere sahip çok katlı yapıların doğrusal olma... more zet: Bu çalışmada, planda A3 türü yapısal düzensizliklere sahip çok katlı yapıların doğrusal olmayan deprem davranışı rijit diyafram ve esnek diyafram kabulü yapılarak, SAP 2000 yapısal analiz programı yardımıyla incelenmiştir. Analizlerin yapılabilmesi için A3 türü düzensizliğe sahip yapılar tasarlanmış ve bu yapıların doğrusal olmayan çözümlemeleri yapılmıştır. Analizlerin sonunda seçilen kolonların kesme kuvvetleri için rijit diyafram ve esnek diyafram kabulüne göre elde edilen sonuçlar tablolar halinde verilerek bir karşılaştırma yapılmıştır. Yapılan bu karşılaştırmada esnek diyafram kabulüne göre yapılan analizlerde rijit diyafram sonuçlarına benzer sonuçlar elde edilmiştir. Buna göre A3 türü düzensizliğe sahip yapıların analizinde, her iki kabulünde kullanılmasında dikkate değer farklar olmadığı görülmüştür. Abstract: In this study, nonlinear earthquake response of multi-story structures which had A3 structural irregularity was investigated with SAP 2000 Structural Analysis Pr...
Concrete is a brittle material which has a low tensile strength and a low tensile strain capacity... more Concrete is a brittle material which has a low tensile strength and a low tensile strain capacity. These weak points of concrete can be resolved by including fibers made of different materials with high technical specifications. This special type of concrete is known as Steel Fiber Reinforced Concrete (SFRC) and exhibits superior properties in terms of ductility, fracture energy, toughness, strength and durability due to the addition of steel fibers when compared to conventional concrete. SFRC has a varied application area. In practice, steel fibers which have different lengths, diameters, and aspect ratios are used. These variable characteristics of steel fibers have highly influence on the performance of SFRC. The goal of this study is aimed at creating a standart foresight in determining the fiber types by comparing the steel fiber types which have the same tensile strengths and different lengths, diameters, and aspect ratios. For this purpose, the series of SFRC specimens which ...
Magazine of Concrete Research, 2015
Strain, 2014
ABSTRACT In the study of concrete fractures, split-tension specimens, such as cylinders, cubes an... more ABSTRACT In the study of concrete fractures, split-tension specimens, such as cylinders, cubes and diagonal cubes, are frequently preferred to beams. However, experimental investigations on concrete reveal that for the same specimen geometry, the nominal strength of specimen decreases with increasing specimen size. This phenomenon is named as the size effect in the fracture mechanics of concrete. Although nominal strength is also highly affected by the width of the distributed load in the split-tension cylinder and cube specimens, this effect can be negligible within the practical range of the load-distributed width in the diagonal cubes. However, the number of theoretical and experimental studies with diagonal split-tension specimens is limited. Besides, a size effect formula for estimating the split-tensile strength of the diagonal cube specimens has not been proposed. In this study, nine series of cube and diagonal cube specimens, with three different sizes but similar geometries, were tested under different load-distributed widths. The ultimate loads obtained from the test results are analysed by the modified size effect law. Subsequently, prediction formulas are proposed, and they are compared with historical test data from the split-cylinder specimens.
KSCE Journal of Civil Engineering, 2015
ABSTRACT The rapid growth of the marble industry introduces concerns regarding the negative impac... more ABSTRACT The rapid growth of the marble industry introduces concerns regarding the negative impact of marble quarrying on the environment, because the cutting of marble creates sludge. The incorporation of marble sludge (powder) into concrete and cement-based products would make significant environmental and economic contributions. This study aims to develop a concrete mixture with maximum marble content that has strength properties comparable to that of the non-marble reference concrete (without marble powder), as opposed to developing a marble powder concrete with maximum compressive strength. The main purpose is to replace sand with marble powder in concrete because such a mixture will be environmentally friendly and economically feasible. The concrete samples are produced by replacing sand with marble powder at 10%, 20%, 30%, 40%, 50% and 90% by volume. The compressive strength values are determined after 7, 28 and 90 days with splitting tensile strength values at 28-th day including water absorption and abrasion resistance values. A feasibility evaluation is performed using parameters such as fresh concrete, compressive strength, sorptivity, abrasion resistance, and estimated cost. Based on the feasibility evaluation it is shown that using up to 40% marble powder in concrete is suitable in accordance with the requirements.
Construction and Building Materials, 2009
The marble has been commonly used as a building material since ancient times. Disposal of the was... more The marble has been commonly used as a building material since ancient times. Disposal of the waste materials of the marble industry, consisting of very fine powders, is one of the environmental problems worldwide today. However, these waste materials can be successfully and economically utilized to improve some properties of fresh and hardened self-compacting concrete (SCC). The aim of this study is to find some relationship between properties of the fresh SCC and the hardened SCC containing marble powder. For this purpose, the mix design approach based on monogram developed by Monteiro and co-workers for normal vibrated concrete was adapted to SCC mixes. In order to obtain this monogram, a series of SCC mixes with different water/cement ratios and water/powder ratios were prepared. Several tests such as slump-flow, T 500 time, L-box, V-funnel and sieve segregation resistance were applied for fresh concrete and tests such as compressive strength and split-tension strength at 7, 28 and 90 days were performed for hardened concrete. In conclusion, the mix design method based on monogram can be suggested for preliminary design in SCC.
Aktif bir deprem kuşağı üzerinde yer alan ülkemizde çok kısa denebilecek zaman aralıkları içerisi... more Aktif bir deprem kuşağı üzerinde yer alan ülkemizde çok kısa denebilecek zaman aralıkları içerisinde yıkıcı depremler meydana gelmiştir. Bu yıkıcı depremler eski çağlardan beri büyük coğrafi değişikliklere ve zararlara sebep olmuştur. Özellikle son yüz yıl içerisinde meydana gelen yıkıcı depremlerden sonra yapı inşasına çeşitli kurallar getirilmeye çalışılmış ve bunlar afet yönetmelikleri şeklinde ortaya konulmuştur. Teknoloji geliştikçe ve depremlerden dolayı meydana gelen can ve mal kayıpları arttıkça bu yönetmelikler değiştirilmiştir. Bayındırlık ve İskan Bakanlığının kurulduğu günden beri ülkemizde sekiz adet deprem yönetmeliği yürürlüğe girmiş, bu yönetmeliklerin hepsi yürürlükte oldukları dönemde meydana gelen depremlerden sonra yetersiz kaldıkları anlaşılmış ve geliştirilmeye çalışılarak, değiştirilmişlerdir. Bu değişiklikler, yapıldıkları dönem içerisinde iyi çalışmalardır. Ancak günümüz bilgi ve teknolojisine göre eksik oldukları aşikardır. Şimdiye kadar depremlerle birlikte hep afet yönetmeliklerinin eksiklikleri gündeme gelmiştir. Bu çalışma da afet yönetmelikleri ne kadar mükemmel hazırlansa da gün geçtikçe yapılan çalışmalardan dolayı yönetmeliğin eksiklerinin oluşacağı ifade edilmeye çalışılmıştır. Daha da önemlisi eksik dahi olsa yönetmelik ve standartlara, projelendirme ve uygulama safhalarında ne kadar uyulduğu belirlenmeye çalışılmıştır. Onlarca bina üzerinde yapılan araştırma sonuçları, önemli miktarda, yönetmelik ve standartlara uyulmadığını ortaya koymuştur.
Materials
Due to the need for high-performance and sustainable building materials, the investigation of the... more Due to the need for high-performance and sustainable building materials, the investigation of the determination of fracture toughness of cement paste using new and sustainable materials, such as cellulose nanocrystals (CNCs) is worthwhile. Contrary to other well-known nano-reinforcement particles, such as carbon nanotubes, CNCs are less toxic; therefore, they have less safety and environmental risks. Fracture behavior of cement paste has been studied intensively for a long time. However, the incorporation of new materials in the cement paste, such as cellulose nanocrystal materials (CNCs), has not been fully investigated. In this paper, the fracture behavior, compressive strength, and hydration properties of cement paste reinforced with cellulose nanocrystal particles were studied. At the age of 3, 7, and 28 days, a three-point bending moment test, and a calorimetry and thermogravimetric analysis, scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDX) ana...
n artificial neural network (ANN) has a wide
application field for mathematical problems. Specifi... more n artificial neural network (ANN) has a wide
application field for mathematical problems. Specifically, an
ANN is successfully applied to problems that are difficult
to solve or do not have any information on their operating
techniques. In this article, an ANN was applied to predict
the concrete mix composition for steel fiber-reinforced
concrete (SFRC). Thus, an ANN model was developed and
trained with data collected from literature. These data have
SFRC mix compositions, workability measurements of fresh
SFRC, compressive strength of SFRCs, and additional information
that affects concrete quality. Additionally, the ANN
included steel fiber volume fraction in the SFRC and steel
fiber properties. With the goal of determining the concrete
mix composition, which is cement dosage, amount of water,
coarse aggregate content, fine aggregate content, and chemical
admixture, an ANN model was developed. The inputs
for the ANN were consistency class of SFRC, compressive
strength of SFRC, maximum size of aggregate, steel fiber
volume fraction, steel fiber length, and diameter. At the end
of the study, a feed forward ANN model with six inputs and
five outputs was successfully trained and used to produce the
correct responses to testing data. Designing SFRC requires
more trial mixtures to obtain the desired quality than does
conventional concrete. In conclusion, artificial neural networks
have a strong potential for predicting concrete mix
composition for SFRC such that without trial mixes and loss
of time, an SFRC design is possible with the desired workability
and mechanical properties.
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Papers by Kürşat Alyamaç
application field for mathematical problems. Specifically, an
ANN is successfully applied to problems that are difficult
to solve or do not have any information on their operating
techniques. In this article, an ANN was applied to predict
the concrete mix composition for steel fiber-reinforced
concrete (SFRC). Thus, an ANN model was developed and
trained with data collected from literature. These data have
SFRC mix compositions, workability measurements of fresh
SFRC, compressive strength of SFRCs, and additional information
that affects concrete quality. Additionally, the ANN
included steel fiber volume fraction in the SFRC and steel
fiber properties. With the goal of determining the concrete
mix composition, which is cement dosage, amount of water,
coarse aggregate content, fine aggregate content, and chemical
admixture, an ANN model was developed. The inputs
for the ANN were consistency class of SFRC, compressive
strength of SFRC, maximum size of aggregate, steel fiber
volume fraction, steel fiber length, and diameter. At the end
of the study, a feed forward ANN model with six inputs and
five outputs was successfully trained and used to produce the
correct responses to testing data. Designing SFRC requires
more trial mixtures to obtain the desired quality than does
conventional concrete. In conclusion, artificial neural networks
have a strong potential for predicting concrete mix
composition for SFRC such that without trial mixes and loss
of time, an SFRC design is possible with the desired workability
and mechanical properties.
application field for mathematical problems. Specifically, an
ANN is successfully applied to problems that are difficult
to solve or do not have any information on their operating
techniques. In this article, an ANN was applied to predict
the concrete mix composition for steel fiber-reinforced
concrete (SFRC). Thus, an ANN model was developed and
trained with data collected from literature. These data have
SFRC mix compositions, workability measurements of fresh
SFRC, compressive strength of SFRCs, and additional information
that affects concrete quality. Additionally, the ANN
included steel fiber volume fraction in the SFRC and steel
fiber properties. With the goal of determining the concrete
mix composition, which is cement dosage, amount of water,
coarse aggregate content, fine aggregate content, and chemical
admixture, an ANN model was developed. The inputs
for the ANN were consistency class of SFRC, compressive
strength of SFRC, maximum size of aggregate, steel fiber
volume fraction, steel fiber length, and diameter. At the end
of the study, a feed forward ANN model with six inputs and
five outputs was successfully trained and used to produce the
correct responses to testing data. Designing SFRC requires
more trial mixtures to obtain the desired quality than does
conventional concrete. In conclusion, artificial neural networks
have a strong potential for predicting concrete mix
composition for SFRC such that without trial mixes and loss
of time, an SFRC design is possible with the desired workability
and mechanical properties.