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Öğe The effect of hybrid fiber and shear stud on the punching performance of flat-slab systems(Elsevier, 2023) Bassurucu, Mahmut; Turk, Kazim; Turgut, PakiIn this paper, for the first time, the binary/ternary hybrid fiber and/or shear stud reinforcement as a measure was used to improve the punching performance of flat-slab systems by innovative selfcompacting concrete (SCC). Because in these slab systems, sudden and brittle punching failure can be seen due to application and design errors, early removal of formwork, changes in the purpose of use of the building, earthquakes, etc. Besides, numerous studies investigated the punching performance of the single fiber and/or shear stud reinforced flat-slab systems, but research into the measures of the hybrid fiber or the combined use of hybrid fiber and shear stud reinforcement, which were the variable parameters of this study, was quite lacking. For this purpose, the half-scale slab-column connection elements were produced from SCC containing different punching measures (binary/ternary hybrid and/or shear stud) and tested to investigate the punching performance of flat-slab systems. In conclusion, it was found that hybrid fiber reinforcement was the best punching measure to improve the punching performance of slabcolumn connection elements with/out shear stud. Besides, 3D graphs were drawn so that designers and researchers could estimate the punching strength and energy absorption capacity for flat-slab systems with/out shear stud based on the parameters of micro fiber type and total volume fraction. On the other hand, empirical formulas were developed to predict the punching strength of binary/ternary hybrid fiber reinforced flat-slab systems with/out shear stud by compressive strength, fiber reinforcement index, the slab useful height, and the punching perimeter parameters.Öğe Effect of rebar arrangements on the structural behavior of RC folded plates manufactured from hybrid steel fiber-reinforced SCC(Elsevier, 2024) Turk, Kazim; Katlav, Metin; Turgut, PakiIn this paper, for the first time in the literature, the effect of different rebar arrangements on the structural behavior of reinforced concrete (RC) folded plates was investigated. For this purpose, RC folded plate specimens having various rebar arrangements fabricated from high-strength hybrid steel fiber-reinforced self-compacting concrete (HSFR-SCC) were tested by subjecting them to four-point bending loading. Then, the structural behavior properties of RC folded plates, such as crack patterns, failure mode, load-midspan displacement relationship, flexural stiffness, ductility, load-strain behavior, and moment-curvature response, were compared and thoroughly assessed. According to the experimental results, different rebar arrangements except for the detailing of transverse rebar induced the RC folded plates to exhibit a combined plate/beam-slab movement behavior, which resulted in higher load-carrying capacity. Notably, it can be said that the detailing of 90-degree hooked steel was generally more effective on the structural behavior of RC folded plates. In addition, the use of hybrid steel fiber instead of transverse rebar provided resistance against shear stresses at the joints and prevented the plates from separating. This application, in constructing the RC folded plates, can reduce labor costs, increase costeffectiveness, and shorten erection time. Therefore, it is obvious that the use of hybrid steel fiber as an alternative to the detailing of transverse rebar for the construction of RC folded plates will ensure some advantages. In conclusion, it is thought that the findings of the study can provide important guidance on the rebar arrangement of RC folded plates in structural engineering applications for structural engineers and designers.Öğe Electrical conductivity and heating performance of hybrid steel fiber-reinforced SCC: The role of high-volume fiber and micro fiber length(Elsevier, 2023) Turk, Kazim; Cicek, Nazli; Katlav, Metin; Donmez, Izzeddin; Turgut, PakiRecently, it has become very popular to develop electrically conductive concrete composites for active deicing and snow-melting of transportation infrastructure. These composites should have stable electrical conductivity and a uniform heating performance, as well as high mechanical and durability properties, for a sustainable solution. In this context, the main motivation of this study is to develop an electrically conductive hybrid steel fiber reinforced self-compacting concrete (HSFR-SCC) composite for ice and snow removal applications. The electrical conductivity and heating performance of self-compacting concrete (SCC) mixtures having different fiber volumes (1.00, 1.25, and 1.50%) and the combination of macro steel fiber with micro steel fibers having lengths of 13 and 6 mm as single and hybrid were experimentally investigated for the first time. For this purpose, a total of ten SCC mixtures were designed, one of which was non-fiber Control, the others had steel fiber volumes of 1.00, 1.25, and 1.50% and different fiber combinations. Workability (slump-flow, T500 and J-ring) tests on HSFR-SCC mixtures were performed with reference to EFNARC. Then, mechanical (compressive and flexural strengths), electrical resistivity, and heating performance tests of 90-day HSFR-SCC samples were carried out. Before the electrical resistivity and heating performance tests, HSFR-SCC samples were kept in an oven at 105 & PLUSMN; 5 degrees C for 24 h to measure their most critical state (dry) performance. Moreover, using multiple linear regression analysis, empirical equations and contour plots were developed to predict the electrical resistivity and temperature increase values of HSFR-SCC samples depending on fiber volumes and combinations. Considering the experimental results, electrically conductive HSFR-SCC mixtures with satisfactory workability and high strength were obtained. The addition of various volumes and combinations of steel fiber to SCC significantly improved the electrical conductivity and heating performance of the concrete, while the mixtures with hybrid fiber were the best for all fiber volumes. As for the different micro fibers added to the HSFR-SCC mixtures, the 13 mm length micro steel fiber was much more effective in improving the electrical resistivity and heating performance of the samples compared to the 6 mm length micro steel fiber. Also, it was found that the fiber-reinforced index of electrically conductive HSFR-SCC samples could be 0.87 for effective and efficient electrical conductivity.Öğe Flexural performance of V-shaped RC folded plates: The role of plate thickness and fiber hybridization(Elsevier Sci Ltd, 2023) Katlav, Metin; Turk, Kazim; Turgut, PakiReinforced concrete folded plates (RC-FPs) are frequently used in structures such as industrial buildings, hangars, swimming pools, and sports halls due to their high load-bearing capacity, low self-weight, economic advantages, and architectural appearance. However, experimental studies on the reinforced concrete (RC) behavior of these new-generation structural members are very limited. For this purpose, this article investigated the effect of plate thickness and fiber hybridization on the flexural performance of V-shaped RC-FPs produced from self-compacting concrete (SCC). With this study, the experimental moment-curvature tool was used for the first time to evaluate the flexural performance of V-shaped RC-FP. A total of sixteen large-scale V-shaped RC-FP specimens with different plate thicknesses (50, 60, 70, and 80 mm) and fiber hybridization (single, binary, and ternary) were manufactured and subjected to a four-point loading after a 90-day curing period. After the experimental load-deflection and moment-curvature curves were obtained, load-bearing capacity, toughness, curvature ductility, and effective flexural stiffness values were calculated and also showed in the crack patterns for all large-scale V-shaped RC-FPs. The empirical equations with high-precision have been developed using multiple linear regression analysis for predicting the load-bearing capacity, toughness, curvature ductility, and effective flexural stiffness of V-shaped RC-FPs based on the parameters of plate thickness and fiber hybridization. Consequently, the use of hybrid fiber-reinforced SCC in the production of V-shaped RC-FPs exhibited superior properties in terms of flexural performance and crack behavior, as well as allowing for accelerated erection of the roof carrier system, resulting in significantly reducing construction time and costs. Also, fiber reinforcement rather than an increase in plate thickness induced significant increases in the flexural performance values of the V-shaped RC-FPs, while ternary fiber hybridization was the best.Öğe The impact of different length hooked-end fibers on the structural performance of RC folded plates(Ernst & Sohn, 2024) Katlav, Metin; Turk, Kazim; Turgut, PakiIn this article, the effect of hooked-end fibers with different lengths on the structural performance of RC-FPs fabricated from hybrid fiber-reinforced self-compacting concrete (HFR-SCC) was investigated. For this purpose, a total of 15 full-scale test samples having different plate thicknesses (60, 70, and 80 mm) were produced and tested under bending after a 90-day curing period. Subsequently, load-carrying capacity (P-p), flexural toughness (Fth), and deflection ductility index (mu(u)) of all RC-FPs were found using load-deflection curves obtained from bending tests, while crack patterns were drawn from the samples tested. Besides, high-precision contour plots are proposed to estimate the structural performance values of RC-FPs depending on plate thickness and fiber reinforcing index. As a result, the best structural performance in RC-FPs was obtained from the use of a longer hooked-end steel fiber together with micro steel fiber as a hybrid, followed by the lower length hooked-end steel fibers as singles. Specifically, irrespective of the plate thickness, the hybrid use of longer hooked steel fibers in combination with micro fibers increased the P-p, Fth, and mu(u) values of RC-FPs on average 1.67, 1.76, and 1.57 times, respectively, compared to the control specimens. As for when using the lower length hooked-end fiber as single, the values of P-p, Fth, and mu(u) increased on average 1.57, 1.69, and 1.30 times. Lastly, whereas plate thickness has little effect on improving the structural performance of thin-walled carrier elements such as RC-FPs, adding fibers in different lengths, aspect ratios, and combinations is much more effective. The collective test results demonstrate that using RC-FPs made of HFR-SCC in the roof carrier system of large span structures could improve structural performance, aesthetics, erection time, and earthquake behavior thanks to reduced dead load.Öğe The influence of disposed fly ash on Ca2+ leaching and physico-mechanical properties of mortars(Elsevier Sci Ltd, 2019) Turgut, Paki; Demir, FeridunFly ash of some thermal power plants is rejected when their chemical compositions do not satisfy the limit values in related standards and consequentially conveyed to landfills. In this study, a rejected fly ash, which has high sulphite, free lime, and magnesium oxide contents and does not comply with the classification standards of fly ashes, having cementing properties, has been examined. This rejected fly ash is moistened with water in the thermal power plant and then transported to landfills. This humidified fly ash that has been in contact with snow and rain for a long time turns to hydrated fly ash. The analysis of this hydrated fly ash showed that the sulphite, free lime, and magnesium oxide content levels of the hydrated fly ash had decreased compared to the original rejected fly ash. After the hydrated fly ash in the landfill was ground and sieved, self-compacting mortars (SCMs) were produced by replacing PC with 10, 20, and 30% hydrated fly ash. At various pH levels, leaching of Ca2+ in SCMs was investigated. Hydrated fly ash is found to be excellent powder material to increase the leaching resistance of Ca2+ in an SCM when used to replace PC with 20% hydrated fly ash. (C) 2019 Elsevier Ltd. All rights reserved.Öğe Investigating the applicability of deep learning and machine learning models in predicting the structural performance of V-shaped RC folded plates(Elsevier, 2024) Katlav, Metin; Ergen, Faruk; Turk, Kazim; Turgut, PakiReinforced concrete folded plates (RC-FPs), which are a special class of shell structures, have recently become very popular in modern architectural and engineering applications because of the need for lightweight and aesthetic structures to cover large areas. However, it is known that studies on the structural performance of RCFPs are insufficient. Therefore, this article presents a study on the development and comparison of different deep learning (DL) and machine learning (ML) models for the prediction of the structural performance of full-scale Vshaped RC-FPs produced from hybrid fiber-reinforced self-consolidating concrete (HFR-SCC) having different plate thicknesses (50, 60, 70, and 80 mm), fiber volumes (1.00% and 1.25%), and combinations (single, binary, and ternary). While vanilla long short-term memory (VLSTM) and bidirectional long short-term memory (BILSTM) are used as DL models, random forest (RF), extremely randomized trees (ERT), and adaptive boosting (AdaBoost) are preferred for ML models. To construct the models, the structural performance results of a total of 44 full-scale V-shaped RC-FPs subjected to four-point bending loading were adopted as the database. In addition to all these, the AdaBoost model is used to determine the relative feature importance of the input parameters. Based on the results, among the DL models, the BILSTM has the best ability to predict the structural performance values of V-shaped RC-FPs (such as R-squared values for maximum load-bearing capacity, cracking load, toughness, and deflection ductility are 0.934, 0.987, 0.972, and 0.812, respectively), while in ML models, this is valid for the ERT (such as R-square values are 0.917 for maximum load-bearing capacity, 0.936 for cracking load, 0.947 for toughness and 0.825 for deflection ductility). On the other hand, DL models predicted all other structural performance values better than ML models, except for deflection ductility. Besides, the most relative important input features for maximum load-bearing capacity and toughness values is plate thickness, whereas for cracking load and deflection ductility values compressive strength is important. In conclusion, it can be emphasized that the use of DL models can provide significant advantages in engineering applications, such as predicting the structural performance of V-shaped RC-FPs.Öğe Lightweight masonry block without Portland cement(Assoc Brasileira Engenharia Sanitaria Ambiental, 2021) Turgut, Paki; Alas, Mehmet Can; Gurel, Muhammed ArifHuge amounts of fly ash - a substance that does not conform to the ASTM C618 classification due to its chemical properties - have been abandoned in landfills around the world, despite their self-cementing property. It has not been used in concrete making applications due to its large amounts of free lime and sulfate contents. The fly ash in these plants is dumped in landfills, causing serious environmental hazards. Fly ash is disposed to the landfills by belt conveyors after being humidified with water. Therefore, the fly ashes humidified in the landfill areas are hydrated in nature. This hydration is further intensified in landfills by rain and snow. Thus, the free lime content of fly ash decreases due to its long hydration process. In this work, the lightweight masonry blocks were produced by mixing normal and hydrated fly ashes or normal, hydrated fly ash and lime without Portland cement. The compressive strength, water absorption, sorptivity, density, porosity, and thermal conductivity values of the samples produced were determined. The results obtained from these tests showed that lightweight masonry blocks could be produced by using these waste materials in building applications.Öğe Optimum limestone powder amount in mortars with over silica fume(Scientific Soc Silicate Industry-Szte, 2019) Turgut, Paki; Ogretmen, AbdullahThe calcium hydroxide (CH) and the calcium silicate hydrate (CSH) are the main hydration products of Portland cement (PC) paste. The CH product causes the durability problems in the PC paste due to the leaching Ca2+ ions. Silica fume is an effective pozzolan to consume CH in the PC paste. It is only effective to convert all CH to CSH if used in excessive amounts in the PC paste. Some problems arise related to segregation, mechanical or physical properties when it is used in excessive amounts. In this study, the optimum limestone powder amount was determined to improve these problems in the mixtures.Öğe Research into effect of hybrid steel fibers on the V-shaped RC folded plate thickness(Elsevier Science Inc, 2022) Katlav, Metin; Turk, Kazim; Turgut, PakiFolded plates have been widely used in some structures, such as industrial buildings, hangar, storage, swimming pools etc., due to their natural stiffness and higher load bearing capacity as well as their economic advantage and aesthetic appearance. The thickness of the reinforced concrete (RC) folded plate is an important parameter in terms of its economic cost and load bearing capacity. The works performed on numerical solution of RC folded plates are enough in the literature although there is no any work related to its thickness effect on flexural behavior. In this work, the behavior of V-shaped RC folded plates having various thicknesses (60, 70 and 80 mm) produced from the self-compacting concrete (SCC) with/out steel fiber are experimentally investigated and developed the empirical formula. After 90-day curing period, full-scale V-shaped RC folded plates are subjected to four-point bending load. The load bearing capacity, load-displacement behavior, toughness and ductility values as well as cracking patterns of all V-shaped RC folded plate specimens are found. It is also seen from experimental results that the use of hybrid fiber reinforced SCC in production of V-shaped RC folded plates provides superior flexural behavior. It is addressed that the thickness of the V-shaped RC folded plates can be effectively reduced and its flexural performance is improved by using hybrid steel fibers. Also, a design method for the V-shaped RC folded plates with hybrid steel fibers is also proposed for estimating the nominal moment bearing capacity of V-shaped RC folded plates with some assumptions based on the ACI 544 procedure.Öğe Uçucu kül, kireç ve cam tozu kullanarak blok üretimi(Pamukkale Üniversitesi Mühendislik Bilimleri Dergisi, 2018) Turgut, PakiÖz: Ülkemizde bulunan Kangal Termik Santrali’nde çok miktarda uçucu kül birikmektedir. Bu santralde üretilen uçucu küller depolama alanlarına dökülmekte, ciddi çevre problemleri ve sağlık sorunlarına sebep olmaktadır. Atık cam da bazı problemler doğurmaktadır. Geri dönüşümü olmayan camların çoğu, çevre dostu bir çözüm olmayan depolama alanına gönderilir. Dolayısıyla, atık cam biyolojik olarak ayrışmadığından, yapı sektöründe kullanılmasına kuvvetle ihtiyaç vardır. Bu çalışmada, uçucu kül, kireç ve cam tozu kullanılarak yapı blokları üretildi. Bloklar 70 o C sıcaklıkta 24, 48, 72 ve 96 sa.’lik sürelerde kür edildi. Blokların basınç ve yarmada çekme dayanımları, su emme, kılcal su emme ve yoğunluk değerleri belirlendi. Kür süresinin yanında, blok içerisindeki kireç ve atık cam tozu gibi ilave malzemelerin miktarlarının da sonuçlar üzerinde direk etkili olduğu bulundu. Elde edilen sonuçlar, bu atık malzemeler kullanılarak blok üretilebileceğini gösterdi.
