Browsing by Author "Yildizel S.A."
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Item Cost optimization of mortars containing different pigments and their freeze-thaw resistance properties(Hindawi Publishing Corporation, 2016) Yildizel S.A.; Kaplan G.; Öztürk A.U.Nowadays, it is common to use colored concrete or mortar in prefabricated concrete and reinforced concrete construction elements. Within the scope of this study, colored mortars were obtained with the addition of brown, yellow, black, and red pigments into the white cement. Those mixtures are examined for their compressive strength, unit weight, water absorption, and freeze-thaw resistance. Subsequent to comparison of these properties, a cost optimization has been conducted in order to compare pigment costs. The outcomes showed that the pore structure in architectural mortar applications plays an important role in terms of durability. And cost optimization results show that light colored minerals can be used instead of white cements. © 2016 Sadik Alper Yildizel et al.Item Major Constructional Dispute Causes in Turkey(De Gruyter Open Ltd, 2016) Yildizel S.A.; Dogan E.; Kaplan G.; Ergut A.The possibility of construction disputes can be reduced, but they cannot be avoided due to the uncertain and risky nature of the building industry. Conflicts between construction parties often have very unfavourable effects, such as cost increases, poor construction quality and time extension in the schedule. Lots of studies have been carried out in order to try and avoid these disagreements. However, there are no common resolution tools or techniques due to the improving conditions and scope of contracted works. Advanced methods and dispute reasons should be fully monitored and updated for the applicable solutions. This paper discusses the current major constructional dispute reasons in Turkey. The questionnaire method was applied within the scope of this study. The questionnaire documents were randomly distributed to 80 contractors to analyse major dispute reasons in Turkey. Analysis of the questionnaire results indicates that the major current dispute causes are poor quality of performed works, delays in progress payments, inefficient site management, poorly written contracts and design mistakes. © 2016 Polish Academy of Sciences.Item A study on the estimation of prefabricated glass fiber reinforced concrete panel strength values with an artificial neural network model(Tech Science Press, 2016) Yildizel S.A.; Öztürk A.U.In this study, artificial neural networks trained with swarm based artificial bee colony optimization algorithm was implemented for prediction of the modulus of rapture values of the fabricated glass fiber reinforced concrete panels. For the application of the ANN models, 143 different four-point bending test results of glass fiber reinforced concrete mixes with the varied parameters of temperature, fiber content and slump values were introduced the artificial bee colony optimization and conventional back propagation algorithms. Training and the testing results of the corresponding models showed that artificial neural networks trained with the artificial bee colony optimization algorithm have remarkable potential for the prediction of modulus of rupture values and this method can be used as a preliminary decision criterion for quality check of the fabricated products. © 2016 Tech Science Press.Item Prediction of Skid Resistance Value of Glass Fiber-Reinforced Tiling Materials(Hindawi Limited, 2017) Yildizel S.A.; Tuskan Y.; Kaplan G.This research focuses on the use of adaptive artificial neural network system for evaluating the skid resistance value (British Pendulum Number; BPN) of the glass fiber-reinforced tiling materials. During the creation of the neural model, four main factors were considered: fiber, calcium carbonate content, sand blasting, and polishing properties of the specimens. The model was trained, tested, and compared with the on-site test results. As per the comparison of the outcomes of the study, the analysis and on-site test results showed that there is a great potential for the prediction of BPN of glass fiber-reinforced tiling materials by using developed neural system. © 2017 Sadik Alper Yildizel et al.Item Simulation optimization for transportation system: A real case application(UIKTEN - Association for Information Communication Technology Education and Science, 2017) Akpinar M.E.; Yildizel S.A.; Karabulut Y.; Doğan E.Simulation applications help decision makers to give right decisions to eliminate some problems such as: create a new firm, need some changes inside a factory; improve the process of a hospital etc. In this engineering simulation study, there are two points which are used by students to arrive at the University. Initial point is the train station and the final point is the arrival point. Students' transportation is provided with buses. The main problem is to decide the number of buses by taking number of student into consideration. To be able to solve this real-life application PROMODEL pack software is used. © 2017 Muhammet Enes Akpinar et al.Item Glass fibre reinforced concrete rebound optimization(Tech Science Press, 2017) Yildizel S.A.; Yiǧit M.E.; Kaplan G.Glass fibre reinforced concrete placement technique generates losses due to rebound effects of the already sprayed concrete particles. Rebounded concrete amount cause a significant difference between the initial mix design and emplaced mix compositions. Apart from the structural differences, it comes with a cost increase which was resulted by the splashed concrete amount. Many factors such as viscosity and quantity of mixes dominate this rebound amount in sprayed glass fibre reinforced concrete applications depending on production technologies and processes; however, this research focuses on the spray distance and the angle of the spray gun which mainly effects the rebound amount in glass fibre reinforced concrete production. This paper aims to understand the required angle and distance for glass fibre reinforced concrete mixes having on-site plastic viscosity values. Glass fibre reinforced mixtures were also modelled with a finite element method based software and, the analysis results were compared with production line results. Results of the analysis and on-site studies showed a decisive correlation between, discharge distance, discharge angle and the viscosity of the concrete. © Copyright 2017 Tech Science Press.Item Wind load design of hangar-type closed steel structures with different roof pitches using abaqus CAE software(UIKTEN - Association for Information Communication Technology Education and Science, 2017) Çiftçioğlu A.Ö.; Yildizel S.A.; Yildirim M.S.; Doğan E.Structures convert the kinetic energy available in the air into potential energy which is in the form of pressure and suction forces reducing or fully stopping its motion. The potential impact of the wind depends on the geometric properties and pertinacity of a building, the angle of the wind flow, its strength and velocity. Design gains importance for tall buildings against the impact of the resonance along with the force based on pressure. Relevant calculations are made in Turkey based on the TS 498 Wind Load Velocity Criterion and this standard is currently being updated. This study develops the wind load design of hangar-type closed steel structures with different roof pitches using Abaqus CAE software. © 2017 Aybike Özyüksel Çiftçioğlu et al.Item The Optimization of Calcareous Fly Ash-Added Cement Containing Grinding Aids and Strength-Improving Additives(Hindawi Limited, 2018) Kaplan G.; Yildizel S.A.; Memiş S.; Öztürk A.U.This is an experimental study which explores the physical, mechanical, and economic factors involved in the production of type CEM II A-B/W cement. In this context, 4 cement additives were used in two different dosages (200 and 800 g/t). Class C fly ash was used for composite cement production at ratios of 5%, 20%, and 35%. It was shown that Blaine fineness increases with the increasing fly ash content. The use of fly ash at ratios of 5% and 20% was not found to have any unfavorable effects on the compressive strength at the early days. It is found that the use of additive for improving the early-age strength is preferable when fly ash is used. It is possible to produce Class 52.5 N cement using additives to improve early strength and 20% fly ash. Loss in strength was observed in cement mortars produced using glycol-based grinding aid. Increasing the dosage of chemical additive also led to loss in strength due to nonhomogeneous distribution of hydration products. As a result, grinding fly ash with clinker and the use of cement chemicals contribute to the cement sector in terms of sustainability. It is possible to produce cements with improved mechanical properties especially with the use of 20% fly ash. © 2018 Gökhan Kaplan et al.Item Abrasion Resistance and Mechanical Properties of Waste-Glass-Fiber-Reinforced Roller-compacted Concrete(Springer New York LLC, 2018) Yildizel S.A.; Timur O.; Ozturk A.U.The potential use of waste glass fibers in roller-compacted concrete (RCC) was investigated with the aim to improve its performance and reduce environmental effects. The research was focused on the abrasion resistance and compressive and flexural strengths of the reinforced concrete relative to those of reference mixes without fibers. The freeze-thaw resistance of RCC mixes was also examined. It was found that the use of waste glass fibers at a rate of 2 % increased the abrasion resistance of the RCC mixes considerably. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.Item Evaluation and optimization of PVA reinforced cementitious composite containing metakaolin and fly ash(Fundatia Serban Solacolu, 2021) Calis G.; Enes Akpinar M.; Yildizel S.A.; Tolga Çöğürcü M.Due to high consumption of natural sources in the production of cement, scholars have been studying alternative materials that can replace cement in the concrete. Metakaolin and fly ash are used by scholars for their chemical properties and filler effect as pozzolanic material. In this study effect of PVA fiber, metakaolin and fly ash in concrete samples are investigated. The number of experiments to be carried out was reduced to 25 with the Taguchi optimization method, in this research. In addition, the recommended mixing ratios were obtained by this preliminary optimization study. Taguchi optimization were applied according to the experimental test results. F-value comparison of each ingredients were analyzed via ANOVA to list the most effective factors on the strengths based on the Taguchi optimization results. Later Response Surface Design was applied to the output parameters of the ANOVA and Taguchi methods to obtain better and detailed clarifications of relations between the input parameters and the strengths. © 2021, Fundatia Serban Solacolu. All rights reserved.Item Investigation of scaffolding accident in a construction site: A case study analysis(Elsevier Ltd, 2021) Dogan E.; Yurdusev M.A.; Yildizel S.A.; Calis G.The construction sector is one of the few high-risk businesses due to occupational accidents, their rate of frequencies, and related serious consequences, sometimes even resulting in the death of individuals. Therefore, it is a vital necessity and priority for employers and employees during the course of a project to comply with occupational safety rules under any circumstances. Nothing should deter or compromise the safety of any individual working in a potential risk environment. Within the scope of this study, the analysis addresses a scaffolding accident that occurred on a construction site. Once the information about how the accident possibly happened was received, the scaffolding in question identified at the construction was kept for an investigation to carry out the corrective and renovation works. In this paper the suspended scaffoldings are firstly categorized. Then how the accident happened was examined and theorized. The examination and analysis were supported by the results. This study is intended to prevent similar accidents and establish necessary precautions as a matter of procedure. © 2020 Elsevier Ltd