Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collections

Permanent URI for this collectionhttps://hdl.handle.net/20.500.13091/3

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Now showing 1 - 20 of 93

Citation - WoS: 52
Citation - Scopus: 62
Analytical Review of Geopolymer Concrete: Retrospective and Current Issues
(MDPI, 2023) Meskhi, Besarion; Beskopylny, Alexey N.; Stel'makh, Sergey A.; Shcherban, Evgenii M.; Mailyan, Levon R.; Shilov, Alexander A.; El’shaeva, Diana; Shilova, Karolina; Karalar, Memduh; Aksoylu, Ceyhun; Özkılıç, Yasin Onuralp
The concept of sustainable development provides for the search for environmentally friendly alternatives to traditional materials and technologies that would reduce the amount of CO2 emissions into the atmosphere, do not pollute the environment, and reduce energy costs and the cost of production processes. These technologies include the production of geopolymer concretes. The purpose of the study was a detailed in-depth analytical review of studies of the processes of structure formation and properties of geopolymer concretes in retrospect and the current state of the issue. Geopolymer concrete is a suitable, environmentally friendly and sustainable alternative to concrete based on ordinary Portland cement (OPC) with higher strength and deformation properties due to its more stable and denser aluminosilicate spatial microstructure. The properties and durability of geopolymer concretes depend on the composition of the mixture and the proportions of its components. A review of the mechanisms of structure formation, the main directions for the selection of compositions and processes of polymerization of geopolymer concretes has been made. The technologies of combined selection of the composition of geopolymer concrete, production of nanomodified geopolymer concrete, 3D printing of building structures from geopolymer concrete, and monitoring the state of structures using self-sensitive geopolymer concrete are considered. Geopolymer concrete with the optimal ratio of activator and binder has the best properties. Geopolymer concretes with partial replacement of OPC with aluminosilicate binder have a denser and more compact microstructure due to the formation of a large amount of calcium silicate hydrate, which provides improved strength, durability, less shrinkage, porosity and water absorption. An assessment of the potential reduction in greenhouse gas emissions from the production of geopolymer concrete compared to the production of OPC has been made. The potential of using geopolymer concretes in construction practice is assessed in detail.
Application of an Artificial Neural Network for Predicting Compressive and Flexural Strength of Basalt Fiber Added Lightweight
(Tulpar Academic Publishing, 2021) Calis, G.; Yıldızel, S.A.; Keskin, U. S.
Concrete is known as one of the fundamental materials in construction with its high amount of use. Lightweight concrete (LWC) can be a good alternative in reducing the environmental effect of concrete by decreasing the self-weight and dimensions of the structure. In order to reduce self-weight of concrete artificial aggregates, some of which are produced from waste materials, are utilized, and it also contributes to de-velop a sustainable material Artificial neural networks have been the focus of many scholars for long time with the purpose of analyzing and predicting the lightweight concrete compressive and flexural strengths. The artificial neural network is more powerful method in terms of providing explanation and prediction in engineering studies. It is proved that the error rate of ANN is smaller than regression method. Furthermore, ANN has superior performance over nonlinear regression model. In this paper, an ANN based system is proposed in order to provide a better understand-ing of basalt fiber reinforced lightweight concrete. In the regression analysis pre-dicted vs. experimental flexural strength, R-sqr is determined to be 86%. The most important strength contributing factors were analyzed within the scope of this study. © 2021, Tulpar Academic Publishing. All rights reserved.
Citation - WoS: 72
Citation - Scopus: 78
Article Info Keywords: Cfrp Reinforced Concrete T-Beams Strengthening Analytical Analysis Anchorage Building Codes Damage Analysis
(Elsevier Science Inc, 2022) Yazman, Şakir; Aksoylu, Ceyhun; Gemi, Lokman; Arslan, Musa Hakan; Hamad, Ahmed Abed; Özkılıç, Yasin Onuralp
Strengthening of shear deficient T-beams is not as easy as rectangular beams due to the presence of slabs. In this study, externally bonded reinforcement (EBR) such type of reinforced concrete shear deficient T-beams with and without anchorage in different CFRP configurations was experimentally and analytically investigated. Pursuant to this goal, nine half-scale T-beams were produced and tested with monotonic loading under four points. Seven of these T-beams are strengthened with partial CFRP strip and one is strengthened with full CFRP wrapped in the shear span. The failures of strengthened beams are initiated with the debonding failure of FRP sheets followed by brittle shear failure. In order to prevent this failure, two specimens with partial CFRP strip are fixed to the beam by using anchors at different angles of 45 and 90. The experimental results indicated that the contribution of EBR to the shear capacity is significant and depends on different variables such as anchorage angle, strengthening type. Moreover, the strengthening method that gives the most effective results in strengthening T-beams are full wrapping CFRP and partial CFRP with a 45-degree anchorage type. The anchorage application increased the shear capacity by 42.6%-53.8% compared to the reference specimens. In addition, the anchors with angle of 45 increased stiffness by 37%. In terms of ductility, the best result was given by the type of strengthening where the slabs were broken and the beam was completely wrapped. This method contributed 42%-80% more to ductility than other methods. The obtained experimental results were also compared with the empirical correlations given by ACI 440.2R-17, TBEC-2019 and FIB-2010 and recommendations are given. Especially in fully wrapped beams, the estimation of ACI was determined to be 96%. The estimations of the other codes are far from meeting the experimental results; therefore, essential improvements should be applied to the codes, especially with regard to CFRP deformation and approaches for anchored connections.
Citation - WoS: 14
Citation - Scopus: 15
Assessing the Structural Behavior of Reinforced Concrete Beams Produced With Macro Synthetic Fiber Reinforced Self-Compacting Concrete
(Elsevier Science Inc, 2022) Ünal, Alptuğ; Uğur, Ahmet Emin
This study was carried out to investigate the effect of polypropylene-based structural macro synthetic fiber (PPF) reinforcement on the behavior of reinforced concrete beams produced with self-compacting concrete (SCC). For this purpose, it was aimed to spread the PPFs homogeneously in the concrete by making use of the fluid form of SCC. The variation of non-fibrous-low-medium-high PPF ratios and stirrup ratios in specimens produced with SCC are the variables of the study. In this study, the shear span/effective depth ratio (a/d) was taken as the limit value of 2.5 in terms of shear and bending, and the behavior of reinforced concrete beams at this critical value was investigated. Within the scope of the study, 16 large-scale specimens were tested under monotonic loads in a 4-point bending setup. Load-displacement, stiffness and energy consumption graphs of the tested specimens were drawn, ductility values were determined, crack distributions were examined and failure modes were determined. The graphs and the determined values were interpreted in detail. In addition, numerical models of the tested specimens were created and analyzed using a finite element program. Experimental study results were compatible with numerical analysis results and similar results were obtained. According to the results obtained, it was observed that the specimens produced with SCC and using PPF reinforcements at appropriate ratios (5 kg/ m3 and 10 kg/m3) exhibited bending failure even if stirrups were not used.
Autogenous Self-Healing Assessment of 1-Year Cementitious Composites
(Springer Science and Business Media B.V., 2021) Yildirim, Gurkan; Ulugol, Huseyin; Ozturk, Oguzhan; Sahmaran, Mustafa
Traditional concrete materials are prone to cracking and as cracks form, durability issues arise which reduce the expected service life of the materials followed by structures incorporating them. This, in many occasions, may lead to repetitive repair and maintenance or even re-construction of certain structural/non-structural sections and structures. Thus, it is highly desirable to reduce the chance and/or further development of cracking. Engineered Cementitious Composites (ECC) are feasible materials to suppress cracking formation and progression through their strain-hardening response under uniaxial tensile loading conditions. Even at the stage of failure, these materials exhibit micron-size cracks which significantly improve the capability to resist against detrimental durability issues. Moreover, these microcracks are constantly reported to be closed through autogenous healing mechanisms with no external interference from outside which significantly improve the mechanical and durability performance and service life of these materials and structures incorporating them. However, the performance of autogenous self-healing in ECC is called into question, especially for late-age specimens since reactions which produce products to plug the micro-size cracks stabilize as the specimens get more and more mature. To clarify this subject, in this study, 1-year-old specimens produced from ECC mixtures incorporated with different mineral admixtures (i.e. Class-F fly ash and ground granulated blast furnace slag) were tested for their self-healing performance. For self-healing evaluation, specimens which were severely preloaded for creating microcracks, were subjected to four different curing conditions which included "Water", "Air", "CO2-water" and "CO2-air" for 90 additional days beyond initial 1 year. Tests used for self-healing assessments were electrical impedance (EI) and rapid chloride permeability (RCP). Results indicate that water is a must-have component for enhanced autogenous self-healing efficiency. "CO2-Water" curing results in the most effective self-healing performance regardless of the composition of ECC mixtures. By properly adjusting mixture proportions and curing conditions, microcracks as large as nearly half a millimeter (458 mu m) can be healed in only 30 days of further curing. Overall, results clearly suggest that late-age autogenous self-healing capability of ECC can be made as effective as the early-age with proper further environmental conditioning and mixture design.
Citation - WoS: 70
Citation - Scopus: 75
Behavior of Cfrp-Strengthened Rc Beams With Circular Web Openings in Shear Zones: Numerical Study
(Elsevier Science Inc, 2022) Özkılıç, Yasin Onuralp; Aksoylu, Ceyhun; Yazman, Şakir; Gemi, Lokman; Arslan, Musa Hakan
In practice, especially the basement floor beams are drilled and damaged by the users. In some cases, this damage to the beams can be significant for the load-bearing element and the whole structure. In this study, the behavior of reinforced concrete beams with circular openings and the failure types resulting from strengthening these beams with CFRP are parametrically investigated. The diameter of the opening/beam height ratio (D/H), con-crete compressive strength, stirrup spacing, the position of the opening to the beam support, the type of CFRP application, CFRP ply orientation, and the number of CFRP layers were selected as parameters. Numerical models were verified using 9 specimens having different circular openings with/without CFRP strengthening and the analyses of 95 numerical models with the selected parameters were carried out utilizing the finite element program, ABAQUS. The ultimate load capacity, ductility, stiffness, energy dissipation capacity and failure modes of the beams were determined. As a result of the study, it was observed that there was no significant loss in ductility for the beams with D/H < 0.3 and the number of CFRP layer and type of application did not have a significant effect on D/H < 0.44. However, for the beams with D/H > 0.64, the CFRP application that completely surrounds openings should be preferred instead of partial CFRP strengthening. In addition, the concrete strength is an effective parameter for the beams with D/H < 0.44. The effect of the stirrup spacings in the beam on the ductile behavior was also limited with the increase in the hole diameter. The number of CFRP layers should theoretically be 4 for an effective strengthening in beams with D/H > 0.44. Finally, U wrapping is recommended instead of using full wrapping. It has been seen that the location and diameter of the hole are very important parameters in the failure type of the beam.
Citation - WoS: 50
Citation - Scopus: 55
Buildings Damages After Elazig, Turkey Earthquake on January 24, 2020
(SPRINGER, 2021) Doğan, Gamze; Ecemiş, Ali Serdar; Korkmaz, Serra Zerrin; Arslan, Musa Hakan; Korkmaz, Hasan Hüsnü
A 6.8-magnitude earthquake that occurred on January 24, 2020, has been effective in Turkey's eastern regions. The earthquake, with recorded peak ground acceleration (PGA) value of 0.292 g, caused the destruction or heavy damage of buildings, especially in the city center of Elazig province. The purpose of this paper was to share the results of detailed investigation in the earthquake-stricken area. Additionally, the causes of damages and failures observed in the buildings were compared to those that had occurred in previous earthquakes in Turkey. In this study, the damages observed in especially RC buildings as well as in masonry and rural buildings were summarized, the lessons learned were evaluated, and the results were interpreted with reference to Turkish earthquake codes. In the study, it was particularly emphasized why the building stock underwent such damage even though the buildings were exposed to earthquake acceleration well below the design acceleration values.
Citation - WoS: 48
Citation - Scopus: 55
Calibration of Swat and Two Data-Driven Models for a Data-Scarce Mountainous Headwater in Semi-Arid Konya Closed Basin
(MDPI, 2019) Köyceğiz, Cihangir; Büyükyıldız, Meral
Hydrologic models are important tools for the successful management of water resources. In this study, a semi-distributed soil and water assessment tool (SWAT) model is used to simulate streamflow at the headwater of Caramba River, located at the Konya Closed Basin, Turkey. For that, first a sequential uncertainty fitting-2 (SUFI-2) algorithm is employed to calibrate the SWAT model. The SWAT model results are also compared with the results of the radial-based neural network (RBNN) and support vector machines (SVM). The SWAT model performed well at the calibration stage i.e., determination coefficient (R-2) = 0.787 and Nash-Sutcliffe efficiency coefficient (NSE) = 0.779, and relatively lower values at the validation stage i.e., R-2 = 0.508 and NSE = 0.502. Besides, the data-driven models were more successful than the SWAT model. Obviously, the physically-based SWAT model offers significant advantages such as performing a spatial analysis of the results, creating a streamflow model taking into account the environmental impacts. Also, we show that SWAT offers the ability to produce consistent solutions under varying scenarios whereas it requires a large number of inputs as compared to the data-driven models.
Citation - WoS: 27
Citation - Scopus: 35
A Comparative Study on Asce 7-16, Tbec-2018 and Tec-2007 for Reinforced Concrete Buildings
(PONTIFICIA UNIV CATOLICA CHILE, ESCUELA CONSTRUCCION CIVIL, 2020) Aksoylu, Ceyhun; Mobark, Ahmed; Arslan, Musa Hakan; Erkan, İbrahim Hakkı
Doctrines of earthquakes and also the latest approaches of earthquake resistant building design in standards need to be revised periodically. While the revisions and updates in the American standards occur over periods of three or five years including limited subjects, in Turkey the same revisions are done once over long periods including the whole subjects of the standards. As examples the standards of 1975, 1998, 2007 and finally 2018 could be given. Especially, in 2018 standard (TBEC-2018) many changes were made over concepts and criteria. The procedure of calculating the earthquake loads in 2018 standards is similar to the one in the American standards of (ASCE-7- 16), however for the element design the changes are shown as developments over the one of 2007 earthquake standard (TEC-2007). The changes made by 2018 standard for calculations of earthquake loads and their effects on civil engineering are very important factors of new building design. The earthquake load affecting a building which is the first factor of earthquake resistant building design shows important differences according to the condition changes in the standard. Based on this motivation in this study reinforced concrete frame type buildings of different elevations were researched by using ETABS (structural software for building analysis and design) according to linear equivalent seismic load method. According to the analysis results of the chosen buildings, a comparison forthe base shear force, top displacement and relative story displacement between TEC-2007, TBEC-2018 and ASCE 7-16 standards was carried out. From the analysis results, it is found that for most of the soil classes while the maximum base shear forces in 3 and 5- story buildings are achievedat TEC-2007, the maximum base shear forces in 7 and 9- story buildings are achieved at TBEC-2018. Also, it is predicted that the higher increment in the design forces of buildings with higher elevations is obtained at TBEC-2018 for strong soils, and at TEC-2007 for weak soils. By considering cracked sections at TBEC-2018 the calculations displacement and period was affected as periods in TBEC-2018 were increased by almost 34% respected to TEC-2007. The same increment ratio was determined for ASCE 7-16 as 45%. Also, as a response for the increments in period, the spectral acceleration determined from the elastic spectrum diagram was decreased. At the end of the study, nonlinear performance analysis was also performed and performance points were determined according to the demand spectra of the seismic codes. ASCE's demand displacement values are in any case lower than Turkish codes. TBEC-2018 reveals less displacement demands in high-rise buildings than TEC-2007. The closest results for the three regulations occurred on the softest grounds.According to the results obtained from the static pushover analysis, a ductile behavior occurred in all of the structural systems and plastic hinge mechanism started from the beams firstly.
Citation - WoS: 19
Citation - Scopus: 25
A Comparative Study on the Rapid Seismic Evaluation Methods of Reinforced Concrete Buildings
(ELSEVIER, 2021) Doğan, Talha Polat; Kızılkula, T.; Mohammadi, M.; Erkan, I. H.; Kabaş, H. Tekeli; Arslan, M. H.
In this study, firstly, visual screening based (VSB) (FEMA 154, RVS and RBTE) and capacity-based (P25, Yakut, AURAP and DURTES) methods which are rapid seismic safety assessment methods of existing buildings have discussed. In addition, the linear and nonlinear earthquake performance procedures of the reinforced concrete structures according to the TBEC-2018 which does not have a rapid evaluation method but includes a detailed performance analysis procedure code were also given. After that, 30 existing reinforced concrete buildings collected from Istanbul-Turkey have been analyzed to all these mentioned methods. In this study results of all 7 different rapid seismic assessment methods were compared with results of TBEC-2018?s linear and nonlinear performance with regard to advantages and disadvantages. Finally, it was seen that while FEMA 154, RVS and RBTE methods are faster to apply on the buildings however P25, Yakut, AURAP and DURTES methods take more time to apply and give more conservative results. It was observed that the results obtained from the non-linear evaluation method of TBEC-2018 are less conservative than other methods. In addition, different results obtained from linear and nonlinear evaluation methods given in TBEC-2018 for the same buildings were also drawn attention.
Citation - WoS: 15
Citation - Scopus: 16
Comparison of Frost Resistance for the Fiber Reinforced Geopolymer and Cementitious Composites [conference Object]
(Elsevier, 2022) Öztürk, Oğuzhan
The design of the structural composites is significant for civil engineering applications which exposures cyclic freeze and thawing action. Accordingly, it is important to design the infrastructures with the appro-priate frost-resistant composite material. Besides a wide range of applications of cement-based compos-ites, geopolymer composites are also of interest under frost action. The current paper deals with the frost resistance of different structural composites with and without fiber reinforcement. A comparison of frost resistance was made between geopolymer and cementitious composites at different curing ages. As frost durability is mainly related to air void parameters, characterization was made for both matrix types in the presence of fiber reinforcement. After applying freeze-thaw cycles, mechanical, water absorption parameters and weight loss were performed for a complete comparison. The results revealed that although inclusion of fiber slightly reduced the compressive strength, reductions after freezing and thaw-ing tests were similar between plain and fiber reinforced cement mortars. On the other hand, frost dam-age surpassed the geopolymerization as higher rate of cyclic frost action lowered the mechanical properties at 28 days compared to 7-day-old specimens. The flexural strength of each mixture was reduced after freeze and thaw cycles, however, it was limited for the fiber reinforced cement mortars. Plain specimens were more prone to cyclic freeze and thaw curing compared to fiber inclusion irrespec-tive of composite type. Geopolymer composites were prone to frost damage as water immersion of geopolymer mortars and excessive sodium content seems to be harmful to geopolymers, especially at earlier ages.Copyright (c) 2022 Elsevier Ltd. All rights reserved.Selection and peer-review under responsibility of the scientific committee of the International Confer-ence on Advances in Construction Materials and Structures.
Citation - Scopus: 2
Comparison of Performance Analysis of a Moment Resisting Framed Structure According To Tbdy 2018 and Asce 41-17
(TUBITAK, 2021) Jamal, Rohullah; Yüksel, Süleyman Bahadır
Due to its simplicity, nonlinear static procedure (NSP) or pushover analysis has been using for the determination of the nonlinear performance of structural and non-structural members. While modeling the determination of the nonlinear properties and deformation capacities for each component of the structure should be determined. Pushover analysis is carried out for either user-defined nonlinear hinge properties or defaulthinge properties, available in some programs based on the TBDY 2018 and ASCE 41-17 standards. Assigning the incorrect default-hinge properties may lead to unreasonable displacement capacities for existing structures. In this study the performance analysis of a single span structure was performed according to TBDY 2018 and ASCE 41-17 codes and the results were compared. Number of stories of the structures were changed for the parametric study. Capacity curves have been obtained as a result of the analysis performed on the building systems. The peak displacement amount calculated according to ASCE 41-17 was obtained more than the peak displacement amount calculated according to TBDY 2018. The amount of base shear force and story shear forces calculated according to TBDY 2018 has been obtained more than ASCE 41-17. The most effective parameters for the plastic hinge properties are plastic hinge length and transverse reinforcement spacing. The results of analyses obtained from the TBDY 2018 and ASCE 41-17 codes show that the structural performance depends on the number of vertical loads, effective stiffness of the structural members and plastic hinge properties. © 2021, TUBITAK. All rights reserved.
Citation - WoS: 40
Citation - Scopus: 43
Compressive Behavior of Pultruded Gfrp Boxes With Concentric Openings Strengthened by Different Composite Wrappings
(MDPI, 2022) Aksoylu, Ceyhun; Özkılıç, Yasin Onuralp; Madenci, Emrah; Safonov, Alexander
Web openings often need to be created in structural elements for the passage of utility ducts and/or pipes. Such web openings reduce the cross-sectional area of the structural element in the affected region, leading to a decrease in its load-carrying capacity and stiffness. This paper experimentally studies the effect of web openings on the response of pultruded fiber-reinforced polymer (PFRP) composite profiles under compressive loads. A number of specimens have been processed to examine the behavior of PFRP profiles strengthened with one or more web openings. The effects of the size of the web opening and the FRP-strengthening scheme on the structural performance of PFRP profiles with FRP-strengthened web openings have been thoroughly analyzed and discussed. The decrease in load-carrying capacity of un-strengthened specimens varies between 7.9% and 66.4%, depending on the diameter of the web holes. It is observed that the diameter of the hole and the type of CFRP- or GFRP-strengthening method applied are very important parameters. All CFRP- and GFRP-strengthening alternatives were successful in the PFRP profiles, with diameter-to-width (D/W) ratios between 0.29 and 0.68. In addition, the load-carrying capacity after reinforcements made with CFRP and GFRP increased by 3.1-30.2% and 1.7-19.7%, respectively. Therefore, the pultruded profiles with openings are able to compensate for the reduction in load-carrying capacity due to holes, up to a D/W ratio of 0.32. The capacity significantly drops after a D/W ratio of 0.32. Moreover, the pultruded profile with CFRP wrapping is more likely to improve the load-carrying capacity compared to other wrappings. As a result, CFRP are recommended as preferred composite materials for strengthening alternatives.
Corrosion Effect on Structural Behaviour of Bolted Steel Connections Under Axial Tension Loads
(Taylor & Francis Ltd, 2022) Yavuz, Günnur; Duysak, Yasin; Arısoy, Hilmi
Corrosion is one of the most important problems and is an inevitable event in metal structures exposed to environmental effects. Corrosion deterioration usually forms in steel and steel-concrete composite bridges and marine structures. Bolted connections in steel structures are the preferred connection types because of their ease of assembly and high strength. In this study, corrosion damages were created in steel plates with bolted connections and the axial load strength, ductility and behaviour of the steel members were investigated. Axial tensile tests have been carried out on steel plates with bolted connections exposed to corrosion at different rates (10% and 20% by mass). According to the axial tensile tests, decreases in average yield strength and average yield strain values were determined as 4% and 10% for 10% corroded specimens, and were determined as 16% and 27% for 20% corroded specimens having 4 mm thick plates, respectively. Similarly, for specimens having a thickness of 6 mm plate, average yield strength and average yield strain values decreased 3% and 5% for 10% corroded specimens, and 13% and 14% for 20% corroded specimens, respectively. Also, it was found that the ultimate strengths and average rupture strains decreased almost proportionally to the amount of corrosion. In addition, finite element analysis was performed in ANSYS program for bolted connections examined experimentally. In terms of ultimate tensile strength, the results were obtained with an average error of 4% in non-corroded 4 mm specimens and 6% in 10% and 20% corroded 4 mm specimens. For 6 mm plate thickness, these values of non-corroded, 10% and 20% corroded specimens were obtained as 9%, 5% and 3%, respectively.
Citation - WoS: 4
Citation - Scopus: 4
Damage Analysis of Golyazi Apartments Building Failed Under Axial Loads: a Case Study in Konya, Turkey
(ELSEVIER SCIENCE INC, 2021) Nakipoğlu, Abdulhamit; Ünal, Alptuğ; Kamanlı, Mehmet
This 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.
Citation - WoS: 52
Citation - Scopus: 51
Damages on Prefabricated Concrete Dapped-End Purlins Due To Snow Loads and a Novel Reinforcement Detail
(ELSEVIER SCI LTD, 2020) Aksoylu, Ceyhun; Özkılıç, Yasin Onuralp; Arslan, Musa Hakan
In prefabricated industrial buildings, damages and collapses may occur under snow loads. If the necessary precautions are not taken, the damage can spread to the whole structure which leads to total collapse. Therefore, it is very crucial for manufacturers to comprehend the nature of the damage and to take necessary precautions to prevent this damage. In this present study, the damages occurred at dapped-end region of prefabricated purlins due to snow load accumulated at the roof and the reasons for these damages were investigated in detail. Pursuant to this goal, comprehensive experimental and numerical studies have been undertaken. 10 specimens with 5 different configurations were tested under four point loading. A novel reinforcement detail and the usage of practical methods used by the manufacturers are selected as main parameters. In all purlins, damages occurred at the dapped-end in shear formation. The experimentally obtained results were compared with field tests and TS9967 design code. It was observed that the specimen with Z type of the proposed novel reinforcement exhibited approximately 30% higher load capacity than that of other specimens. Moreover, the numerical analyses were performed in order to determine optimum Z type reinforcement for dapped-end purlin beams using finite element methods.
Citation - Scopus: 1
Determination of Autogenous Self-Healing Capability of Cementitious Composites Through Non-Destructive Testing
(Springer Science and Business Media B.V., 2021) Yıldırım, Gürkan; Öztürk, Oğuzhan; Ulugöl, H.; Hatem, M.; Şahmaran, Mustafa
Unlike conventional concrete and fiber reinforced concrete, Engineered Cementitious Composites (ECC) display closely spaced multiple microcracks through strain/deflection-hardening response when subjected to tension-based loadings. These multiple microcracks allow ECC to be characterized with inherent autogenous self-healing capability. With the emergence of cement-based composites exhibiting multiple tight cracking, possibility for favoring the intrinsic self-healing behavior increased. Self-healing phenomenon in cementitious composites is being studied extensively nowadays. Although, great number of tests utilized to evaluate the self-healing mechanism in cementitious composites, implementation can be time consuming in some occasions and results from different tests may not always well-suit. Thus, different from other studies in literature, direct electrical impedance (EI) measurements were used in the present study to evaluate the self-healing performance of ECC mixtures along with rapid chloride permeability test (RCPT) and resonant frequency (RF) measurements. Experimental results revealed that EI testing is rather easy to perform and takes very limited time but it seems that the method itself is markedly influenced by anything modifying ionic state of specimens. Therefore, it looks like a hard task to very accurately assess the self-healing performance of ECC specimens considering the fact that both ongoing hydration and calcium carbonate precipitation which are regarded to be the main mechanisms contributing to the autogenous self-healing significantly changes the specimens’ pore solution chemistry. Well-fitting exponential relationship exists between EI and RCPT measurements at different ages regardless of the mixture and specimen type. However, results from RF tests do not correlate either with EI or RCPT results which is attributed to the different parameters having paramount influence on the individual tests. Although results from different tests do not always correlate well among themselves, three different tests used for the present study are capable of monitoring the self-healing behavior with differing efficiencies. © 2021, The Author(s), under exclusive license to Springer Nature Switzerland AG.
Citation - WoS: 1
Citation - Scopus: 1
Determination of Autogenous Self-Healing Capability of Cementitious Composites Through Non-Destructive Testing
(Springer Science and Business Media B.V., 2021) Yildirim, Gurkan; Ozturk, Oguzhan; Ulugol, Huseyin; Hatem, Muhammed; Sahmaran, Mustafa
Unlike conventional concrete and fiber reinforced concrete, Engineered Cementitious Composites (ECC) display closely spaced multiple microcracks through strain/deflection-hardening response when subjected to tension-based loadings. These multiple microcracks allow ECC to be characterized with inherent autogenous self-healing capability. With the emergence of cement-based composites exhibiting multiple tight cracking, possibility for favoring the intrinsic self-healing behavior increased. Self-healing phenomenon in cementitious composites is being studied extensively nowadays. Although, great number of tests utilized to evaluate the self-healing mechanism in cementitious composites, implementation can be time consuming in some occasions and results from different tests may not always well-suit. Thus, different from other studies in literature, direct electrical impedance (EI) measurements were used in the present study to evaluate the self-healing performance of ECC mixtures along with rapid chloride permeability test (RCPT) and resonant frequency (RF) measurements. Experimental results revealed that EI testing is rather easy to perform and takes very limited time but it seems that the method itself is markedly influenced by anything modifying ionic state of specimens. Therefore, it looks like a hard task to very accurately assess the self-healing performance of ECC specimens considering the fact that both ongoing hydration and calcium carbonate precipitation which are regarded to be the main mechanisms contributing to the autogenous self-healing significantly changes the specimens' pore solution chemistry. Well-fitting exponential relationship exists between EI and RCPT measurements at different ages regardless of the mixture and specimen type. However, results from RF tests do not correlate either with EI or RCPT results which is attributed to the different parameters having paramount influence on the individual tests. Although results from different tests do not always correlate well among themselves, three different tests used for the present study are capable of monitoring the self-healing behavior with differing efficiencies.
Citation - WoS: 14
Citation - Scopus: 16
Determination of Damage Levels of Rc Columns With a Smart System Oriented Method
(SPRINGER, 2020) Doğan, Gamze; Arslan, Musa Hakan; Baykan, Ömer Kaan
In this study, a method that is fast, economical and satisfying in terms of accuracy rate has been developed in order to determine the post-earthquake damage level of reinforced concrete column elements dependent on the damage image on the column surface. In order to represent the Turkish building stock, reinforced concrete columns were produced complying with the 2007 and 2018 Turkish Earthquake Code (TEC-2007 and TBEC-2018) and, in order to represent the existing building stock made before 2000, reinforced concrete columns which are non-complying with the code have been produced. A total of 12 reinforced concrete columns produced in 1/1 scale with square cross sections were tested under earthquake resembling reversible cycling lateral load and axial force. For each cycle, a data set was created by matching the surface images taken from the determined regions of the columns with the damage levels specified in TEC-2007 and TBEC-2018 depending on the load-displacement values measured on the column during the experiment. As a result of the experimental study, a total of 390 damage images were obtained for each load and displacement level. Image processing application was performed by using MATLAB on the damage images and the cracks on the column surface were separated. Parameters such as total cracks area, total cracks length, maximum crack length and maximum crack width have been obtained to represent the amount of damage on the column through the feature extraction process of the cracks in the images. The characteristics of the cracks were classified by support vector machines, decision trees, K-nearest neighborhood, Discriminant Analysis, Ensemble algorithms, which are machine learning classifiers, and the damage states for the columns were estimated. The estimation success from the classifiers ranges from 64 to 80%. In this study, it has been seen that the proposed and developed intelligent system will be open to development and will be a good alternative to existing conventional systems for the determination of column damage.
Citation - WoS: 8
Citation - Scopus: 9
Determination of Hydraulic Characteristics of Flow Over a Triangular Sectioned Weir by Using Experimental and Numerical Modeling
(UNIV TEHRAN, DANISHGAH-I TIHRAN, 2021) Yıldız, Ali; Martı, Ali İhsan; Göğüs, Mustafa
The spillways of hydraulic structures transfer excessive water from dam reservoir to the downstream in a safe and controlled manner. A labyrinth or triangular weir is a flat spillway folded in plain view. The labyrinth weirs provide an increase in crest length for a given channel width and increase the flow capacity for a given weir load. As a result of the increased flow capacity, the labyrinth and triangular weirs require less space in the dam body than the flat weirs. In this study, experiments were carried out on the labyrinth weirs containing triangles of different heights and numbers by using 3 different weir heights (P=20cm, 30cm, and 40 cm) and 4 different weir shapes. Each experiment was repeated for 30 different discharge values. The effects of weir height and weir shape on the total head over the weir (H-T) and discharge (Q) were investigated. In addition, the numerical models of all experimental setups were created by ANSYS-Fluent program using Computational Fluid Dynamics (CFD). By comparing the results obtained from the numerical models with the physical models, the accuracy of the numerical models was tested. According to the results, as the number of the triangles (N) of the weir increases, the discharge coefficient (Ca) decreases. The weir height (P) does not have a major effect on the discharge.

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