Browsing by Author "Ozkilic, Yasin Onuralp"

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Citation - WoS: 1
Citation - Scopus: 1
Bending Performance of Reinforced Concrete Beams With Partial Waste Glass Aggregate Replacement Assessed by Experimental, Theoretical and Digital Image Correlation Analyses
(Nature Portfolio, 2025) Ozkilic, Yasin Onuralp; Basaran, Bogachan; Aksoylu, Ceyhun; Karalar, Memduh; Zeybek, Ozer; Althaqafi, Essam; Umiye, Osman Ahmed
This study examines the usage of waste glass aggregate (WGA) for the consumption of sustainable reinforced concrete regarding the replacement of fine aggregate (FA) and coarse aggregate (CA). For this purpose, a series of tests consisting of a total of 12 beams were carried out to explore the bending performance. The quantity of the longitudinal reinforcement section area and WGA percentage were selected as the prime variables. For this purpose, the aggregate was swapped with WGA with weight percentages of 10% and 20% for the FA and 10% and 20% for coarse aggregate. The test outcomes revealed that the crack and bending properties of the reinforced concrete beams (RCBs) were greatly affected by the section area of tension reinforcement and the percentage of the WGA. The WGA percentage might be effectively used as 20% of the partial replacement of FA. With the addition of FA to the mixture, the load-bearing capacity of RCB increases. The increase in the WGA percentage by more than 10% might cause a considerable reduction in the capacity of the RCBs, especially when the longitudinal reinforcement ratio is high. Furthermore, the digital image correlation method was used to show the cracks/micro-cracks and to define displacement in RCBs.
Effect of Stirrup Spacing and Recycled Steel Wires on the Shear and Energy Dissipation of Pultruded GFRP Hybrid Beams
(Sage Publications Ltd, 2025) Ozkilic, Yasin Onuralp; Kalkan, Ilker; Aksoylu, Ceyhun; Madenci, Emrah; Umiye, Osman Ahmed; Althaqafi, Essam; Beskopylny, Alexey N.
The contribution of Recycled Steel Wires (RSW) to the shear strength and behavior of pultruded glass fiber reinforced polymer (P-GFRP) hybrid composite beams with reinforced concrete infill, denoted as P-GFRP beams, was investigated experimentally and analytically in the current study. A total of six specimens with varying RSW ratio and stirrup spacing of the reinforced concrete (RC) core and a fixed shear span-to-beam depth ratio were tested to failure. The addition of RSW to concrete was established to have greater contribution to the beam strength with increasing stirrup spacing, that is, decreasing transverse reinforcement ratio. The contribution of RSW to energy dissipation capacity was found to be more pronounced in the elastic range of beam response as compared to the inelastic range. The theoretical calculations indicated that the RC core prevented the P-GFRP encasement from complete failure due to shear-induced material rupture at the initial stages of loading. By maintaining their integrity, the reinforced concrete-filled box beams (RCFB) were able to resist loading until complete failure associated with flexure-induced material rupture and web compression buckling. A strut-and-tie model providing accurate strength estimates for P-GFRP beams was also proposed.
Citation - Scopus: 2
Effect of Stirrup Spacing on Strengthening Beams With Insufficient Shear Capacity Using Innovative Mechanical Steel Stitches
(Ernst & Sohn, 2025) Aksoylu, Ceyhun; Uysal, Yusuf; Basaran, Bogachan; Ozkilic, Yasin Onuralp; Arslan, Musa Hakan
This study investigates experimentally and analytically the effect of stirrup spacing variation on the behavior of reinforced beams in the 45 degrees-inclined innovative mechanical steel stitches (MSSs) application for the strengthening of reinforced concrete beams with insufficient shear capacity. Within the scope of the experimental study, four-point loading tests were carried out under vertical loads by selecting stirrup spacing (250, 350, and 450 mm) and MSS spacing (d/3, d/2.5, d/2, d/1.7, and d/1.4) as variable parameters (d is effective depth of beam). In this context, a total of 12 beam specimens with dimensions of 125 x 250 x 2500 mm each with 250 and 450 mm stirrup spacing were produced, one reference specimen with each stirrup spacing and specimens reinforced with five different MSS spacings were tested; in addition, the test results of a reference beam with 350 mm stirrup spacing and beams reinforced with six different MSS spacings in the literature were used for comparison. Within the scope of the analytical study, the MSS spacing required for the beams to reach the flexural capacity was investigated by selecting the ratio of tensile reinforcement and the presence/absence of compressive reinforcement as variable parameters. In the study, the changes in failure mode, strength, ductility, stiffness, and energy consumption capacities of beams due to different stirrup and MSS spacings were analyzed. According to the experimental results obtained at the end of the study, it was observed that the reference beam with 250 mm stirrup spacing carried 32% and 35% more load than the reference beams with 350 and 450 mm spacing, respectively. Tightening the MSS up to 75 mm increased the shear capacity of beams with 450, 350, and 250 mm stirrup spacing up to 46.1%, 37.4%, and 23.5%, respectively. As the stirrup spacing of the reinforced beams decreased, the contribution of the MSS application to the shear capacity decreased. In addition, the failure mode of the beams changed from diagonal tension mode to splitting mode by increasing the MSS spacing. According to the analytical results, it was observed that MSS contributed more to the flexural capacity in beams with low longitudinal reinforcement ratio, and the performance of MSS was significantly improved in the absence of compression reinforcement.
Citation - WoS: 24
Citation - Scopus: 27
Effects of Stirrup Spacing on Shear Performance of Hybrid Composite Beams Produced by Pultruded GFRP Profile Infilled with Reinforced Concrete
(Springernature, 2022) Ozkilic, Yasin Onuralp; Gemi, Lokman; Madenci, Emrah; Aksoylu, Ceyhun
Pultruded Glass Fiber-Reinforced Polymer (pultruded GFRP) composite produced by the pultrusion method has become popular in civil engineering applications due to its lightness, corrosion resistance and high strength. However, the use of the pultruded profile combining with reinforced concrete is still limited due to a lack of knowledge. Therefore, the behavior of the pultruded GFRP profile infilled with reinforced concrete beams (hybrid beams) is investigated. This study focused on the effects of stirrup spacing for the hybrid beams. Pursuant to this goal, a total of eight different beams were tested under fourpoint loading. One reference beam without the pultruded profile and seven hybrid beams having different stirrup spacings were considered. Moreover, the hybrid beams with and without stirrups were wrapped by unidirectional GFRP composite to investigate the effects of stirrup spacing on shear capacity of the beams strengthened by GFRP composite. The experimental findings revealed that tightening stirrups increased the load and energy dissipation capacities of the hybrid beams; however, it could not prevent brittle failure. On the other hand, wrapping hybrid beams with GFRP composite increased the load and energy dissipation capacities and also prevented brittle failure regardless of the presence of the stirrups. Therefore, it is strongly recommended that the unidirectional pultruded profiles should be strengthened with 90 degrees GFRP wrapping to have ductile behavior.
Citation - WoS: 6
Citation - Scopus: 6
Experimental, Theoretical and Digital Image Correlation Methods to Assess Bending Performance of RC Beams With Recycled Glass Powder Replacing Cement
(Nature Portfolio, 2025) Aksoylu, Ceyhun; Basaran, Bogachan; Karalar, Memduh; Zeybek, Ozer; Althaqafi, Essam; Beskopylny, Alexey N.; Ozkilic, Yasin Onuralp
This study investigates the use of Waste Glass Powder (WGP) as a proportional replacement for cement in sustainable concrete production. In addition, changes in the bending capacity of the Reinforced Concrete (RC) Beams were examined by adding WGP at different rates (0%, 10%, 20%, 30%) to RC Beams with different steel reinforcement ratios (rho s = 0.0077 i.e. Phi 8, rho s = 0.0121 i.e. Phi 10, rho s = 0.0174 i.e. Phi 12). To pursue this goal, 12 test specimens were evaluated and then confirmed to explore the bending productivity. The amount of longitudinal bar section area and WGP proportion were chosen as the key parameters. For this aim, experimental and analytical investigations were carried out by replacing cement with WGP in weight ratios of 10%, 20%, and 30% and considering three different longitudinal reinforcements (rho s = 0.0077 i.e. Phi 8, Phi 10, Phi 12). The test results showed that tension reinforcement section area and WGP proportion dimensions had dissimilar rupture and flexure effects on RC Beams. Furthermore, investigational tests are confirmed with the help of the Digital Imagining Method, and the image processing method was used to identify the cracks/microcracks in RC Beams. Consequently, it is observed that each WGP ratio in the concrete combination has dissimilar bending and rupture properties on the RC Beams for experimental tests-10% of partial replacement of cement. It was found that a WGP ratio of more than 10% can significantly reduce the bending capacity of RC Beams. When the experimental test beams were compared with the analytical results, it was observed that the experimental results and analytical calculations are in agreement.
Highly Effective Injection Composites With Fly Ash and Microsilica for Soil Stabilization
(MDPI, 2025) Ozkilic, Yasin Onuralp; Beskopylny, Alexey N.; Aksoylu, Ceyhun; Stel'makh, Sergey A.; Shcherban', Evgenii M.; Madenci, Emrah; Kosykh, Alexey
Injection composites based on mineral binders are widely used for soil stabilization, using jet grouting technology to solve various geotechnical problems. Cement, which contains toxic components and worsens the ecology of the environment, is typically the main mineral component used to manufacture injection composites. Reducing cement consumption in the production of building materials is currently of great importance. This study developed highly effective, environmentally friendly injection composites for soil stabilization based on three mineral components: Portland cement, fly ash (FA), and microsilica (MS). FA was introduced into the composites as a partial Portland cement substitute, in amounts ranging from 5 to 50% in 5% increments. The properties of fresh and hardened composites, including the density, flow rate, water separation, compressive strength at 7 and 28 days, and the structure and phase composition of the composites, were studied. The inclusion of FA in the composition of composites contributes to a decrease in density by 16.9%, from 1.89 g/cm3 to 1.57 g/cm3, and cone spread by 9%, from 30.1 cm to 27.4 cm, and an increase in water bleeding by 91.4%, from 3.5% to 6.7%, respectively. Based on the results of the experimental studies, the most effective dosage of FA was determined, which amounted to 20%. An increase in compressive strength was recorded for composites at the age of 7 days of 8.3%, from 33.6 MPa to 36.4 MPa, and for compressive strength at the age of 28 days of 9.4%, from 41.3 MPa to 45.2 MPa, respectively. SEM and XRD analysis results show that including FA and MS promotes the formation of additional calcium hydrosilicates (CSH) and the development of a compact and organized composite structure. The developed composites with FA contents of up to 50% exhibit the required properties and can be used for their intended purpose in real-world construction for soil stabilization.
The Influence of Fiber-Form Waste Tire Aggregates on the Flexural Strength, Ductility, and Energy Dissipation of Pultruded GFRP-Rubberized Concrete Hybrid Beams
(MDPI, 2025) Ecemis, Ali Serdar; Karalar, Memduh; Beskopylny, Alexey N.; Stel'makh, Sergey A.; Shcherban, Evgenii M.; Aksoylu, Ceyhun; Ozkilic, Yasin Onuralp
This study investigates the effects of different proportions of waste rubber fiber aggregates on the flexural behavior of reinforced concrete beams. Beam specimens were prepared with different proportions (5%, 10%, and 15%) of waste rubber fiber aggregates, and composite beams formed with pultruded GFRP profiles were tested under vertical load. According to the results of this study, cube compressive strength, cylinder tensile strength, and beam flexural strength decreased by 27.5%, 50%, and 47.6%, respectively, with the use of a 15% waste rubber aggregate. As a result of the four-point bending tests performed on reinforced concrete beams, the maximum load-carrying capacity of the beams decreased significantly after increasing the waste rubber aggregate ratio to 10% and 15%. However, a general improvement in the ductility of the beams was observed. One of the main results of this study is that when the waste rubber aggregate content is 5%, the best balance between strength and ductility is achieved, and the performance closest to the reference beams is obtained. The tests also revealed that the & Oslash;10-5% specimen exhibited higher performance in terms of both load-carrying capacity and yield stiffness. On the other hand, although the 15% waste rubber aggregate ratio caused a decrease in the maximum load-carrying capacity. along with an increase in the diameter of the tensile reinforcement, this decrease was quite low. Finally, an overall decrease in energy consumption capacity was observed with increasing waste rubber aggregate content in all test beams. This can be attributed to the acceleration of shear damage in the beam and the shrinkage of the area under the load-displacement curve as the amount of waste increases. Additionally, SEM analyses were conducted in order to investigate the microstructural behavior of the rubberized concrete. This study has shown that the use of waste rubber aggregates can be environmentally and economically beneficial, especially at the 5% level.
Innovative Material Using Mechanical Steel Stitches in Shear-Deficient Reinforced Concrete Beams With Different Concrete Strengths
(Ernst & Sohn, 2025) Aksoylu, Ceyhun; Basaran, Bogachan; Arslan, Musa Hakan; Ozkilic, Yasin Onuralp
Shear damage in beams limits ductility and leads to a sudden loss of load-bearing capacity. Thus, shear strengthening is essential for maintaining structural performance. Although many conventional methods exist, they are practically restrictive due to implementation difficulties, architectural constraints, and high costs. Therefore, there is a need for strengthening techniques that are both economical and easy to implement. In this study, the results of a series of experimental studies on strengthening using mechanical steel stitches (MSS), which is an innovative method, are presented. A total of 24 beams with four different concrete compressive strengths, named R5, R10, R15, and R20, were tested, 4 of which were reference beams and 20 were reinforced with MSS. MSS spacings were chosen as a function of effective depth as d/3, d/2.5, d/2, d/1.7, and d/1.4. As a result of the four-point bending test of the reference and strengthened beams, the load-displacement relationship, stiffness, ductility, and energy dissipation capacity were calculated, and their experimental behavior and failure modes were evaluated. As a result of the study, depending on the MSS spacing, as the compressive strength of the concrete increases, the effectiveness of the MSS on the shear capacity increases by up to 15%. When the yield stiffnesses were examined, a transition between 2% and 26% occurred, depending on the concrete compression strength. Thus, shear strengthening is essential for maintaining load-carrying capacity and structural performance. In the analytical calculation, it was observed that all beams strengthened with MSS contributed between 6% and 69% in the load-carrying capacity compared to the reference beams. When the damage analysis at the end of the experiment was examined, by increasing the MSS spacing, the failure mode of the beams changed from a diagonal tension failure to a splitting failure.
Nonlinear Finite Element Evaluation of the Seismic Performance of the Historic Ayvat Masonry Weir
(Springer, 2025) Mollamahmutoglu, Cagri; Ozturk, Mehdi; Aksoylu, Ceyhun; Madenci, Emrah; Ozkilic, Yasin Onuralp
A nonlinear seismic assessment of the 18th-century Ayvat masonry weir was performed by integrating three-dimensional finite-element (FE) modeling with Ground-Penetrating Radar (GPR) surveys. A detailed ABAQUS model of approximately 70000 continuum elements was developed and calibrated using laboratory-measured stone-mortar properties and GPR-derived foundation profiles. Nonlinear time-history analyses were carried out under Turkish Earthquake Code (TEC-2018) hazard levels DD1 (2%/50 yr) and DD2 (10%/50 yr) for both principal-axis and 45 degrees-rotated records. Under the 45 degrees-rotated DD1 record (EQ1R), crest-to-base displacements reached up to 0.30 m, and the isolated local maximum damage parameter (PEMAX*) reached 0.47. In contrast, under the 45 degrees-rotated DD2 record (EQ2R), maximum displacements remained below 0.01 m and PEMAX* did not exceed 0.14, thereby preserving global stability while inducing residual strains at the abutments. Stress concentrations were consistently detected at material discontinuities and joint zones. Based on these results, targeted retrofitting measures, including joint reinforcement and localized strengthening, are recommended to ensure the structural safety and preserve the heritage integrity of historic masonry weirs.
Optimization of Concrete with Human Hair Using Experimental Study and Artificial Neural Network via Response Surface Methodology and Anova
(Nature Portfolio, 2025) Yildizel, Sadik Alper; Karalar, Memduh; Aksoylu, Ceyhun; Althaqafi, Essam; Beskopylny, Alexey N.; Stel'makh, Sergey A.; Ozkilic, Yasin Onuralp
The increasing demand for sustainable construction materials has prompted the investigation of non-biodegradable waste, such as human hair (HH), for concrete reinforcement. This study seeks to evaluate the impact of HH fiber on the fresh, physical, and mechanical characteristics of concrete. HH was incorporated in varying proportions (1-5% by weight of cement), along with modifications in cement content, to ascertain optimal performance conditions. An extensive experimental program was executed, succeeded by the utilization of Artificial Neural Networks (ANN) to formulate predictive models for compressive strength (CS), flexural strength (FS), and splitting tensile strength (STS). Furthermore, Response Surface Methodology (RSM) and Analysis of Variance (ANOVA) were utilized to identify statistically significant factors and optimize the mix design. The findings indicated that the mechanical performance of concrete enhanced with HH inclusion up to 3%, after which a deterioration ensued, presumably due to inadequate dispersion and workability challenges. The ANN models precisely predicted mechanical outcomes, while the RSM-derived models demonstrated strong correlations, with R2 values of 0.9434, 0.9365, and 0.9311 for CS, FS, and STS, respectively. ANOVA confirmed the significance of model inputs with p-values below 0.05. Furthermore, SEM, EDX, and XRD analyses validated the integration of HH into the concrete matrix and substantiated the observed mechanical properties. This study confirms the feasibility of HH as a sustainable fiber in concrete, enhancing critical performance metrics when applied at optimal dosages. The amalgamation of ANN, RSM, and ANOVA offers a thorough methodology for optimizing innovative concrete composites and clarifying the mechanisms underlying performance enhancement.
Citation - WoS: 2
Citation - Scopus: 2
Porosity Analysis and Thermal Conductivity Prediction of Non-Autoclaved Aerated Concrete Using Convolutional Neural Network and Numerical Modeling
(MDPI, 2025) Beskopylny, Alexey N.; Shcherban', Evgenii M.; Stel'makh, Sergey A.; Elshaeva, Diana; Chernil'nik, Andrei; Razveeva, Irina; Ozkilic, Yasin Onuralp
Currently, the visual study of the structure of building materials and products is gradually supplemented by intelligent algorithms based on computer vision technologies. These algorithms are powerful tools for the visual diagnostic analysis of materials and are of great importance in analyzing the quality of production processes and predicting their mechanical properties. This paper considers the process of analyzing the visual structure of non-autoclaved aerated concrete products, namely their porosity, using the YOLOv11 convolutional neural network, with a subsequent prediction of one of the most important properties-thermal conductivity. The object of this study is a database of images of aerated concrete samples obtained under laboratory conditions and under the same photography conditions, supplemented by using the author's augmentation algorithm (up to 100 photographs). The results of the porosity analysis, obtained in the form of a log-normal distribution of pore sizes, show that the developed computer vision model has a high accuracy of analyzing the porous structure of the material under study: Precision = 0.86 and Recall = 0.88 for detection; precision = 0.86 and recall = 0.91 for segmentation. The Hellinger and Kolmogorov-Smirnov statistical criteria, for determining the belonging of the real distribution and the one obtained using the intelligent algorithm to the same general population show high significance. Subsequent modeling of the material using the ANSYS 2024 R2 Material Designer module, taking into account the stochastic nature of the pore size, allowed us to predict the main characteristics-thermal conductivity and density. Comparison of the predicted results with real data showed an error less than 7%.
Retraction: Application of Waste Ceramic Powder as a Cement Replacement in Reinforced Concrete Beams Toward Sustainable Usage in Construction
(Elsevier, 2024) Aksoylu, Ceyhun; Ozkilic, Yasin Onuralp; Bahrami, Alireza; Yildizel, Sadik Alper; Hakeem, Ibrahim Y.; Ozdoner, Nebi; Karalar, Memduh
[No Abstract Available]
Retraction: Crashworthiness Performance of Filament Wound Gfrp Composite Pipes Depending on Winding Angle and Number of Layers
(Elsevier, 2024) Hakeem, Ibrahim Y.; Ozkilic, Yasin Onuralp; Bahrami, Alireza; Aksoylu, Ceyhun; Madenci, Emrah; Asyraf, Muhammad Rizal Muhammad; Fayed, Sabry
[No Abstract Available]
Citation - WoS: 14
Citation - Scopus: 16
Shear and Bending Performances of Reinforced Concrete Beams With Different Sizes of Circular Openings
(MDPI, 2023) Ozkilic, Yasin Onuralp; Aksoylu, Ceyhun; Hakem, İbrahim Y.; Özdoner, Nebi; Kalkan, İlker; Karalar, Memduh; Stel'makh, Sergey A.
The present study pertains to the effects of transverse opening diameters and shear reinforcement ratios on the shear and flexural behavior of RC beams with two web openings across different spans, i.e., a single opening in each half-span. Within the scope of the study, a total of 12 RC beams with five different opening diameter-to-beam depth ratios (0, 0.20, 0.27, 0.33, 0.40, and 0.47) and two shear reinforcement ratios were tested to failure under four-point bending. The load capacities, ductilities, rigidities and energy dissipation capacities in the elastic and plastic ranges of beam behavior were compared. Furthermore, the load capacities of the beams were compared to the existing analytical shear strength formulations in the literature. The test results indicated that whether an RC beam with openings has adequate or inadequate amounts of shear reinforcement, the frame-type shear failure becomes much more pronounced with increasing opening diameter. The reductions in the load capacity and modulus of toughness with increasing opening diameter are more considerable in the presence of inadequate amounts of shear reinforcement, while the beam ductility is less affected in shear-deficient RC beams with openings as compared to the ones with adequate shear reinforcement.
Citation - WoS: 1
Citation - Scopus: 2
Shear and Flexural Performance of Reinforced Concrete Beams with Recycled Concrete Aggregates
(De Gruyter Poland Sp ZOO, 2025) Ozkilic, Yasin Onuralp; Althaqafi, Essam; Karalar, Memduh; Aksoylu, Ceyhun
This study investigates the effects of recycled concrete aggregate (RCA) content and stirrup spacing on the structural performance of reinforced concrete beams (RCBs) under flexural and shear loading. A total of 24 RCB specimens were cast with RCA replacement ratios of 0, 10, 20, and 40%, and tested under four different stirrup spacings: 100, 160, 200, and 270 mm. The experimental program evaluated key structural parameters, including load-bearing capacity, stiffness, ductility, and energy dissipation. The results demonstrated that increasing the RCA content generally led to reductions in both flexural and shear strength. The most significant shear strength loss (46.86%) occurred at 40% RCA with 270 mm stirrup spacing, while the highest flexural load reduction (11.24%) was observed in beams with & Oslash;10 longitudinal reinforcement and 40% RCA. Moreover, although higher RCA content generally reduced stiffness, ductility, and energy dissipation, specimens with wider stirrup spacing exhibited relatively better performance under shear, suggesting that transverse reinforcement can partially mitigate RCA-induced performance losses in shear-dominated beams. These findings suggest that while RCA can be used in RCBs, proper detailing of transverse and longitudinal reinforcement is essential to maintain adequate structural performance.
Citation - WoS: 3
Citation - Scopus: 3
Shear and Flexural Performance of Reinforced Geopolymer Concrete Beams Cured Under Ambient and Oven Conditions With Environmentally Friendly Waste Steel Tire Wire Additives
(Nature Portfolio, 2025) Ozkilic, Yasin Onuralp; Celik, Ali Ihsan; Aksoylu, Ceyhun; Karalar, Memduh; Mydin, Md Azree Othuman; Althaqafi, Essam; Umiye, Osman Ahmed
In this study, the effects of Granulated Blast Furnace Slag (GBFS) and Waste Steel Wire (WSW) admixtures on the flexural and shear performances of Reinforced Geopolymer Concrete Beams cured under oven and ambient conditions were investigated experimentally and analytically in detail. The research used 100 mm and 270 mm stirrup spacings and changed GBFS and WSW with 0%, 10%, 20%, and 1%, 2%, and 3%, respectively. To evaluate flexural and shear strength of reinforced GPC, 100 x 150 x 1000 mm samples were made. The results showed how material proportions affect flexural, and shear beam mechanical performance and ductility. In flexural beams, increasing the GBFS ratio to 10% enhanced load bearing capability and preserved ductility. However, 20% of GBFS reduced load bearing capability and brittle fractures. It was found that mixtures with GBFS of 10% and WSW of 3% are optimum for flexural beams. For shear beams, brittle fracture was observed for all GBFS and WSW ratios and ductile behavior was not achieved. Increasing GBFS content to 10% boosted capacity from 2.05 to 19.37%, however increasing it to 20% dropped capacity from 2.72 to 15.10%. Increasing WSW content enhanced load bearing capability, however increasing GBFS content over 10% did not. It is emphasized that different materials and design methods should be investigated to ensure ductile behavior in shear beams. Increasing the WSW ratio from 0 to 3% boosted energy consumption capacity by 2.78 times. But raising the GBFS ratio to 20% reduced energy consumption capacity by 66%. In addition, AS3600 predicted beam damage more correctly in different conventional computations. This study shows that the GBFS ratio should be limited to 10% and the WSW ratio to 3%. This combination maintains ductility in flexural beams and gives a safe design limit in shear beams while increasing load bearing capability. The results obtained provide important information that will shed light on new designs.
Sustainable Concrete with Waste Tire Rubber and Recycled Steel Fibers: Experimental Insights and Hybrid PINN-CatBoost Prediction
(MDPI, 2025) Ecemis, Ali Serdar; Yildizel, Sadik Alper; Beskopylny, Alexey N.; Stel'makh, Sergey A.; Shcherban', Evgenii M.; Aksoylu, Ceyhun; Ozkilic, Yasin Onuralp
The growing environmental concern over waste tire accumulation necessitates innovative recycling strategies in construction materials. Therefore, this study aims to develop and evaluate sustainable concrete by integrating waste tire rubber (WTR) aggregates of different sizes and recycled waste tire steel fibers (WTSFs), assessing their combined effects on the mechanical and microstructural performance of concrete through experimental and analytical approaches. WTR aggregates, consisting of fine (0-4 mm), small coarse (5-8 mm), and large coarse (11-22 mm) particles, were used at substitution rates of 0-20%; WTSF was used at volumetric dosages of 0-2%, resulting in a total of 40 mixtures. Mechanical performance was evaluated using density and pressure resistance tests, while microstructural properties were assessed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The findings indicate systematic decreases in density and compressive strength with increasing WTR ratio; the average strength losses were approximately 12%, 20%, and 31% at 5%, 10%, and 20% for WTR substitution, respectively. Among the WTR types, the most negative effect occurred in fine particles (FWTR), while the least negative effect occurred in coarse particles (LCWTR). The addition of WTSF compensated for losses at low/medium dosages (0.5-1.0%) and increased strength by 2-10%. However, high dosages (2.0%) reduced strength by 20-40% due to workability issues, fiber clumping, and void formation. The highest strength was achieved in the 5LCWTR-1WTSF mixture at 36.98 MPa (approximate to 6% increase compared to the reference/control concrete), while the lowest strength was measured at 16.72 MPa in the 20FWTR-2WTSF mixture (approximate to 52% decrease compared to the reference/control). A strong positive correlation was found between density and strength (r, Pearson correlation coefficient, approximate to 0.77). SEM and EDX analyses confirmed the weak matrix-rubber interface and the crack-bridging effect of steel fibers in mixtures containing fine WTR. Additionally, a hybrid prediction model combining physics-informed neural networks (PINNs) and CatBoost, supported by data augmentation strategies, accurately estimated compressive strength. Overall, the results highlight that optimized integration of WTR and WTSF enables sustainable concrete production with acceptable mechanical and microstructural performance.
Citation - WoS: 14
Citation - Scopus: 17
Utilizing Recycled Glass Powder in Reinforced Concrete Beams: Comparison of Shear Performance
(Nature Portfolio, 2025) Karalar, Memduh; Basaran, Bogachan; Aksoylu, Ceyhun; Zeybek, Ozer; Althaqafi, Essam; Beskopylny, Alexey N.; Ozkilic, Yasin Onuralp
In this research, the effect of using waste glass powder (WGP) as a partial replacement for cement on the flexural behavior of reinforced-concrete-beams (R-C-Bs) was investigated. For this aim, a total of 9 specimens were produced, and investigational experimentations were conducted to evaluate the flexural performances of R-C-Bs. Subsequently, the cement was partially replaced with WGP with weight percentages of 0%, 10%, 20% and 30%. Furthermore, the influence of stirrup spacing (SS) in the longitudinal reinforcement on productivity was also examined. The results presented indicate that the efficient WGP percentage might be considered as 10% of the partial replacement of cement. Increasing the WGP percentage within the cement by more than 10% may considerably reduce the ability of the R-C-Bs, noticeably when the lengthwise reinforcement proportion is high. Additionally, the experimental shear strengths of R-C-Bs attained from the flexural tests were compared with the shear capacities estimated using Eurocode 2 and ACI 318 - 19 regulations. It was concluded that the shear capacities calculated with ACI318-19 are much lower than the values calculated with EC2. Furthermore, it may be observed that ACI318-19 calculates the shear capacities of R-C-Bs to be 15-51% higher than those of the experimental results. Furthermore, the Digital Image Correlation (DIC) was used to study the flexural cracks/micro-cracks in R-C-Bs. Comparisons indicate that DIC has similar deformations and fracture properties for the R-C-Bs as the experimental tests. Finally, it was considered that the optimum consumption quantities determined by the results of the present research would be a guide for future investigation.
Web Crippling of Pultruded GFRP Profiles: A Review of Experimental, Numerical, and Theoretical Analyses
(MDPI, 2025) Soumbourou, Mohamed Ahmed; Aksoylu, Ceyhun; Madenci, Emrah; Ozkilic, Yasin Onuralp
Glass fiber reinforced polymer (GFRP) composite profiles produced by pultrusion method are widely used as an alternative to traditional building materials due to their lightness and corrosion resistance. However, these materials are susceptible to crushing type fractures known as "web crippling" especially under local loading due to their anisotropic structure and limited mechanical strength. Understanding web-crippling behavior is crucial for the safe and efficient structural application of pultruded GFRP profiles. This study report narrated the review of experimental, numerical, and analytical investigations of web-crippling behavior of pultruded GFRP profiles. Highlights of the major findings include profile geometry and detailing of the flange-web joint, loading types (end-two-flange (ETF), interior-two-flange (ITF), end bearing with ground (EG), interior bearing with ground (IG)), bearing plate dimensions, presence of web openings, and elevated temperatures. It also considers the limitations of current standards, along with new modeling techniques that incorporate finite element analysis as well as artificial intelligence. Damage types such as web-flange joint fractures, crushing, and buckling were comparatively analyzed; design approaches based on finite element modeling and artificial intelligence-supported prediction models were also included. These insights provide guidance for optimizing profile design and improving predictive models for structural engineering applications. Gaps in current design standards and modeling approaches are highlighted to guide future research.