Profile URL: https://hdl.handle.net/20.500.13091/11882
Job Title:Doç. Dr.
Email Address:tyilmaz@ktun.edu.tr
Main Affiliation:02.02. Department of Civil Engineering
Status: Current Staff
ORCID:
0000-0001-7668-1496
0000-0001-7668-1496Scopus ID:
57188968298
57188968298YÖK Akademik: 3CD2521B0BABFBAE
Google Scholar:
WsmzgysAAAAJ
WsmzgysAAAAJWeb of Science ID:
ABD-7319-2021
ABD-7319-2021Name Variants:
YIlmaz, Tolga Yilmaz, Tolga
29 results
Scholarly Output Search Results
Now showing 1 - 10 of 29
Article Impact Behavior of Low Strength Concrete Slab Strengthened With Fan Type Anchored Carbon Fiber-Reinforced Polymer Strips(Ernst & Sohn, 2023) Caliskan, Ozlem; Aras, Murat; Yılmaz, Tolga; Anil, Ozgur; Erdem, R. TuğrulThis study investigated the behavior of slabs produced with low compressive strength concrete without reinforcements under the effect of sudden dynamic impact loading. In addition, an experimental study was conducted by proposing a strengthening method with anchored carbon fiber-reinforced polymer (CFRP) strips to strengthen the nonreinforced slabs with low-strength concrete against sudden dynamic impact loads to improve their performance. The variables examined in the experimental study were the placement of the CFRP strips adhered to the concrete slabs for strengthening purposes and anchors in the strips. A constant energy level of impact loading was applied to the concrete slab test specimens with the authors' free weight drop test setup. The acceleration-time, displacement-time, strain-time, and applied impact loading-time measurements on the concrete slabs were examined, and comments were made about the strengthening method applied to the slab test specimens. In addition, numerical analysis of the tested concrete slabs with ABAQUS finite element software was performed, and the results were compared with the experimental results. In the comparison, it was investigated to what extent numerical analysis and this type of impact analysis can be done realistically and compatible with the experimental results. Within the scope of the study, the strengthening method applied with fan- type anchored CFRP strips significantly improved and increased the impact performance of concrete slabs produced with low-strength concrete.Article Citation - WoS: 2Citation - Scopus: 3Low-Velocity Impact Behavior of Two-Way Sfrc Slabs Strengthened With Steel Plate(Springernature, 2024-05-08) Al-Hagri, Mohammed Gamal; Döndüren, M. Sami; Yılmaz, Tolga; Anıl, Özgür; Erol, Hakan; Şengel, Hasan SelimStructural systems and structural elements can often suffer severe damage or even completely collapse under the effect of sudden dynamic impact loading, which is a different type of loading that is not considered during their design. Research on how structures behave under impact loading and how they can be strengthened to perform better against this type of loading has increased to avoid such undesirable severe damage. Within the scope of this study, it is aimed to improve the behavior and increase the performance of two-way steel fiber-reinforced concrete (SFRC) slabs, one of the leading structural elements that can be affected by impact loading, using steel fiber concrete (SFC) and placing steel plates on the surface of the RC slab. Within the scope of the study, the effects of placing FRC as layers in different positions within the slab and placing the steel plate on different surfaces of the slabs were examined. Impact loading was applied using a drop weight test setup designed by the authors, and the acceleration-time, displacement-time, and impact loading-time behaviors of the RC slabs were measured and interpreted. The use of fiber concrete in RC slabs and strengthened with steel plates increased the maximum acceleration values by an average of 3% and 113%, respectively. The use of fiber concrete in RC slabs reduced the maximum displacement and residual displacement values by an average of 2% and 25%, respectively. Placing steel plates on the slabs reduced the maximum displacement and residual displacement values by an average of 270% and 199%, respectively. In addition, the energy absorption capacities of RC slabs were calculated, and how they were affected by experimental variables was examined. Numerical analyses of the RC slabs tested in the study were also conducted using ABAQUS finite element software, and the results obtained were compared with the experimental ones.Article Citation - WoS: 19Citation - Scopus: 19Experimental, Analytical, and Numerical Investigation of Punching Behaviour of Two-Way Rc Slab With Multiple Openings(Elsevier Ltd, 2022) Akkaya, Sercan Tuna; Mercimek, Ömer; Ghoroubi, Rahim; Anıl, Özgür; Erbaş, Yaşar; Yılmaz, TolgaBecause of its advantages, reinforced concrete (RC) flat slabs have become increasingly popular in recent years. On the other hand, flat slabs have the problem of being vulnerable to punching, which is a dangerous type of collapse. The openings around the column are the most important factor affecting this behavior. The effects of multiple opening positions in two-way reinforced concrete slabs on punching behavior were explored in this study. The factors studied were opening sizes (300 × 300 mm, 500 × 500 mm, and 700 × 700 mm) and opening positions (parallel, diagonal, and adjacent). In this context, ten two-way reinforced concrete (RC) slabs with a length of 2000 × 2000 × 120 mm were made and tested under punching loading from a 200 × 200 mm square column in the slab's middle. The analytical capacity equations presented in TS 500 (TSE, 2000), ACI 318 (ACI, 2019), and Eurocode 2 (CEN, 2002) were used to determine the specimens' ultimate load capabilities. In addition to these studies, finite element models of the slabs were created using ABAQUS finite element software, and comments on how successful the numerical model could be were made by comparing the analysis findings with the experimental results. According to the research, as the openings grew larger, unfavorable results were achieved in ultimate load capacity, initial stiffness, and energy dissipation capacity, with the most unsuccessful results in the test specimens with the adjacent opening position. © 2022 Institution of Structural EngineersArticle Citation - WoS: 2Citation - Scopus: 2Investigation of the Effects of Shear Reinforcement Ratio and Opening Size on the Impact Behavior of Rc Beams Produced With Geopolymer Concrete(Elsevier Science inc, 2025-05-01) Erkan, I. Hakki; Aslan, Salih; Erol, Hakan; Sengel, H. Selim; Yilmaz, Tolga; Arslan, M. Hakan; Anil, OzgurInvestigations have revealed that construction, manufacturing, and the construction sector collectively account for a significant proportion of global energy consumption and emissions. The issue of climate change has become a matter of significant concern, with the slowing down of problems caused by it and the prevention of some of them before they occur occupying a prominent position on the global agenda. Concrete remains the most prevalent building material globally. The primary component of concrete utilized in its production is cement. However, cement is a building material that requires significant energy inputs during manufacture and generates substantial carbon emissions. Consequently, research on environmentally benign alternative concrete formulations that can be produced using alternative binding agents and recycled waste materials instead of cement has witnessed a gradual surge. Research on geopolymer concrete, one of these types, has intensified increasingly in the last decade. Research investigating the behavior of reinforced concrete structural elements produced using geopolymer concrete under static and cyclic earthquake loading has gradually increased in the literature. However, a literature review reveals a paucity of studies examining the behavior of reinforced concrete (RC) members produced using geopolymer concrete under sudden dynamic loading, such as that caused by impact forces. For this reason, an experimental study was planned, and 16 RC beams produced using standard concrete and geopolymer concrete, without and with circular web openings of different sizes, with insufficient and sufficient shear strength, were tested under impact loading using a drop weight test setup. Under the effect of constant energy level impact loading applied to the specimens, the variations of acceleration, displacement, and impact loading values for time were measured, general impact behavior, failure mechanisms, and energy dissipation values were calculated and interpreted, and it was investigated how they were affected by the experimental variables examined in the study. The openings in the RC beams and the increase in the size of the openings negatively affected the performance of all beams under impact loading. In addition, the RC beams tested in the experimental study were modeled using Ls-Dyna finite element software. The values obtained from the numerical analysis were compared with the experimental results, and the extent to which successful analyses could be performed was interpreted.Article LTBWTB: a Mathematica Software to Evaluate the Lateral-Torsional Buckling Load of Web-Tapered Mono-Symmetric I-Section Beams(MDPI, 2025) Yilmaz, TolgaWeb-tapered beams with I-sections, which are aesthetic and structurally efficient, have been widely used in steel structures. Web-tapered I-section beams bent about the strong axis may undergo out-of-plane buckling through lateral deflection and twisting. This primary stability failure mode in slender beams is known as lateral-torsional buckling (LTB). Unlike prismatic I-beams, the complex mode shape of web-tapered I-section beams makes it challenging or even impossible to derive a closed-form expression for the LTB load under certain transverse loading conditions. Therefore, the LTB assessment of web-tapered I-section beams is primarily performed using finite element analysis (FEA). However, this method involves multiple steps, requires specialized expertise, and demands significant computational resources, making it impractical in certain cases. This study proposes an analytical approach based on the Ritz method to evaluate the LTB of simply supported web-tapered beams with doubly or mono-symmetric I-sections. The proposed analytical method accounts for web tapering, I-section mono-symmetry, types and positions of transverse loads, and beam slenderness. The method was implemented in Mathematica to allow the rapid evaluation of the LTB capacity of web-tapered I-beams. The study validates the LTB loads computed using the developed Mathematica package against results from shell-based FEA. An excellent agreement was observed between the analytically and numerically calculated LTB loads.Article An Improved Finite Element Code for Assessment of Corroded Reinforced Concrete Beams Subjected To Impact Loading(Elsevier, 2026) Kocer, Mustafa; Mercimek, Omer; Colak, Gamze Nur; Uludogan, Ahmet Muhammed; Yilmaz, TolgaThis study develops an enhanced nonlinear finite element (FE) model to investigate the impact behavior of reinforced concrete (RC) beams with varying longitudinal reinforcement ratios and corrosion damage under different impact energy levels. The model, implemented in LS-DYNA and incorporating strain-rate effects, corrosion-induced reductions in reinforcement cross-sectional area and yield strength, degradation of concrete compressive strength, and bond-slip deterioration at the steel-concrete interface, is validated against experimental data from the literature in terms of peak impact force, displacement response, and energy absorption. Following validation, a comprehensive parametric study is conducted on twelve RC beams with two reinforcement ratios, two corrosion levels, and three impact energies. The numerical results show that corrosion markedly increases maximum and residual displacements, accelerates stiffness degradation, and amplifies damage accumulation. At the same time, higher reinforcement ratios enhance impact stiffness, limit crack propagation, and improve post-impact recovery. Peak impact force is relatively insensitive to corrosion and reinforcement ratio, whereas displacement-, stiffness-, and damage-index-based parameters provide a more unambiguous indication of deterioration. Crack patterns obtained from effective plastic strain contours further reveal a transition from predominantly flexural failure to mixed flexural-shear mechanisms with increasing impact energy and corrosion severity. Overall, the findings highlight the critical role of corrosion and reinforcement detailing in governing the dynamic response of RC beams under impact loading and underscore the need to use stiffness- and deformation-based indicators, rather than force alone, in the assessment and design of corrosion-damaged members.Article On the Evaluation of Lateral-Torsional Buckling of Web-Tapered Cantilevers With Doubly Symmetric I-Section(2023) Yılmaz, Tolga; Sertçelik, Mustafa; Şengel, Hasan SelimRecently, structural engineers have tended to design stronger and lighter structures due to economic reasons, technical developments in computer-aided design, and improvements in manufacturing. The demand for designing stronger and lighter structures has led to the compulsory considering structural efficiency and stability loss at the design level. Lateral-torsional buckling (LTB) is a major stability loss for web-tapered cantilevers with doubly symmetric I-section, which are aesthetic and structurally efficient. The elastic LTB loads of these cantilevers should be calculated at the design level since the LTB may happen before bending stress reaches yield. Studies related to the LTB of cantilevers are rare and require numerical solutions since the LTB mode shape of cantilevers is complex compared to simply supported beams. The present study introduces an analytical procedure based on the energy method for calculating elastic LTB of web-tapered cantilevers with doubly-symmetric I-section in two different forms. The analytical model considers different transverse load types, positions of loads, and web tapering degrees. The analytical solutions were validated with one-dimensional finite element analysis using a beam element. Excellent accord-ance between results was demonstrated. The general LTB behavior of web-tapered cantilevers with doubly symmetric I-section was clarified with detailed comments based on results obtained from the presented analytical model.Article Behavior of Corroded RC Beams with Varying Corrosion Percentages and Shear Reinforcement Ratio under Impact Load(SAGE Publications Inc, 2026) Erol, Hakan; Boğa, Ahmet Raif; Yılmaz, Tolga; Uludoğan, Ahmet Muhammed; Koçer, Mustafa; Şengel, H. Selim; Anil, ÖzgürThis study aims to experimentally and numerically investigate the behavior of reinforced concrete (RC) beams designed to exhibit flexure and shear failure behavior by changing the shear reinforcement ratio, which has undergone different corrosion rates under the effect of impact loading. Corrosion is the damage type that affects RC members the most throughout their economic life due to environmental conditions. Studies in literature examine the behavior of corroded RC beams under the effect of static and reversible repeated dynamic loads such as earthquakes or wind. However, the literature does not present a comprehensive experimental study examining the behavior of corroded RC beams under the effect of sudden dynamic impact loads. The planned study selects the corrosion percentage of RC beams and the status of exhibiting shear or flexural failure as experimental variables in a design approach. Acceleration, displacement, and loading time changes under the impact loading applied to corroded RC beams are measured and evaluated with the authors' free weight drop test setup. The beams' collapse mechanisms and energy dissipation capacities are interpreted, and the effects of corrosion on the behavior of the beams under the impact loading are investigated. The results obtained from the experimental part of the study and the numerical analysis results performed with the Ls-Dyna finite element software are compared, and the extent to which successful FEA analyses could be obtained is interpreted. It is observed that the corrosion occurring in RC beams negatively affected behavior under the impact loading significantly, reduced the maximum acceleration values measured from the beams by an average of 118%, and increased the maximum displacement and permanent residual displacement values occurring under the applied impact loading effect by an average of 142% and 167%, respectively. Corrosion also negatively affected the energy dissipation capacities of RC beams under the impact loading effect significantly and caused an average decrease of 81%.Article Citation - Scopus: 1A Novel Strengthening Technique for Shear Deficient Reinforced Concrete Beams: 45° Inclined Mechanical Steel Stitches under Impact Loading(Elsevier Science Inc, 2026) Erol, Hakan; Arslan, Musa Hakan; Yilmaz, Tolga; Aksoylu, Ceyhun; Sengel, H. Selim; Anil, Ozgur; Karabacak, EnesIt is well-known that shear failure is a collapse mechanism that is the riskiest, fastest, and catastrophic and occurs with no visible signs of damage or prior warning for reinforced concrete (RC) beams. Therefore, to prevent brittle shear failure, the RC beams should include sufficient shear reinforcement, such as stirrups, and be designed to have sufficient shear capacity. However, the RC beams' shear capacity becomes inadequate for various reasons. One of these reasons may be the acting of the impulsive impact load, which is uncommon and disregarded in the design phase on the RC beams. An experimental program was conducted to examine the impact behavior and failure mode of shear-deficient RC beams in the scope of the present study. Besides, it aims to investigate the effectiveness of the strengthening method using mechanical steel stitches (MSS) in improving the general behavior, failure mode, and performance of shear-deficient RC beams exposed to impact load. In the experimental study, the impact loading energy level applied to RC beams with insufficient shear strength, the impactor geometry to which the impact loading is applied and the spacing of the MSS elements placed externally on the beams for strengthening purposes were investigated as variables. The time histories of the accelerations, displacements, and impact loads were measured. They were interpreted how they are affected by experimental variables examined in the experimental study. Furthermore, the finite element model of the specimens was generated in the LS-DYNA software, and the experimental and numerical results were compared by performing finite element analysis in terms of failure modes and general behavior. The strengthening method applied to RC beams with insufficient shear strength using the MSS technique generally improved the behavior of RC beams under impact loading, increased their performance, increased the maximum acceleration values by an average of 37%, and reduced the maximum and permanent residual displacement values by an average of 107% and 240%, respectively.Article Numerical Evaluation of Reinforced Concrete Slabs With Fixed Support Under Impact Load(2022-09-29) Şengel, H. Selim; Yilmaz, TolgaReinforced concrete (RC) structural members may be subjected to impact load besides quasi-static load or other dynamic loads like earthquake and wind loads in their service periods. Many research emphasized that although impact load acts on structural members for a short time, it caused considerable damage to these members or even collapses the whole structure. Thus, it becomes crucial to consider and accurately evaluate the impact load effect in the design process. The present study intends to introduce a finite element model (FEM) verified with the test data for the accurate evaluation of load-deflection behavior and damage patterns of the fixed supported RC slabs exposed to impact load. First, a nonlinear FEM including strain-rate effect for both concrete and steel reinforcement, and crack visualization algorithm has been established by using LS-DYNA software. Then, the dynamic responses obtained by the present FEM have been compared with the experimental data presented in a previous study existing in the literature and it is found that the present FEM yields accurate results for the RC slab subjected to impact load and it can be safely used in the design process. In the second part of the study, using the verified FEM, the effects of applied input impact energy, the application point of impact load, and hammer geometry on the dynamic responses and failure characteristics of the RC slabs exposed to the impact loading were investigated and interpreted in detail.
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Research Topics
Domains
Physical Sciences
Fields
EngineeringPhysics and Astronomy
Subfields
Electrical and Electronic EngineeringAtomic and Molecular Physics, and OpticsBuilding and ConstructionCivil and Structural Engineering
Specific Research Areas
Photonic and Optical Devices
Advanced Fiber Laser Technologies
Semiconductor Lasers and Optical Devices
Structural Behavior of Reinforced Concrete
Structural Response to Dynamic Loads
Sustainable Development Goals
11SUSTAINABLE CITIES AND COMMUNITIES
9
Research Products
3GOOD HEALTH AND WELL-BEING
2
Research Products
9INDUSTRY, INNOVATION AND INFRASTRUCTURE
2
Research Products
13CLIMATE ACTION
1
Research Products
12RESPONSIBLE CONSUMPTION AND PRODUCTION
1
Research Products
Documents
31
Citations
439
h-index
13
Documents
25
Citations
392
Publication Collaboration
| Affiliation Name | Count |
|---|---|
| Gazi University | 27 |
| University of Central Florida | 25 |
| Konya Technical University | 17 |
| Eskişehir Osmangazi University | 16 |
| Princeton University | 8 |
1 / 7
Data obtained from OpenAlex
| Journal | Count |
|---|---|
| Structures | 5 |
| Challenge Journal of Structural Mechanics | 3 |
| Structural Concrete | 3 |
| Journal of Building Engineering | 2 |
| Mechanics Based Design of Structures and Machines | 2 |
Current Page: 1 / 4
Scholarly Output
29
Articles
26
Views / Downloads
63/35
Supervised MSc Theses
2
Supervised PhD Theses
0
WoS Citation Count
131
Scopus Citation Count
143
Patents
0
Projects
0
WoS Citations per Publication
4.52
Scopus Citations per Publication
4.93
Open Access Source
9
Supervised Theses
2
Scopus Quartile Distribution
Competency Cloud
