Yazar "Martins, Carlos Humberto" seçeneğine göre listele

Listeleniyor 1 - 4 / 4
  • Küçük Resim Yok
    Öğe
    Mechanical behavior in terms of shear and bending performance of reinforced concrete beam using waste fire clay as replacement of aggregate
    (Elsevier, 2023) Ozkilic, Yasin Onuralp; Basaran, Bogachan; Aksoylu, Ceyhun; Karalar, Memduh; Martins, Carlos Humberto
    In this experimental and analytical study, waste fire clay (WFC) was consumed by the use of replacing fine aggregate (FA) in confident amounts. It is targeted to remove the current sustainable complications by confirming the consumption of WFC in reinforced concrete beams (RCBs) as raw materials. For this purpose, FAs were partially replaced with WFC in proportions of 0 %, 10 %, 20 %, and 30 %. Based on this motivation, a series of experimental studies were performed on 12 + 12 small-scale bending and shear RCBs of 100x150x1000mm, considering altered WFC and stirrup spacing. While the percentage of WFC in the RCBs was selected as 0 %, 10 %, 20 %, and 30 % by weight, correspondingly, the longitudinal reinforcement was taken into account as Phi 12, Phi 10, Phi 8. Besides, while the longitudinal tension and compression reinforcements of constant 2 Phi 12 and 2 Phi 6, the stirrup spacing was chosen as 160 mm, 200 mm, and 270 mm. As a result of the study, increasing the tensile reinforcement ratio has made the WFC less effective. Similarly, as stirrup spacing decreases, stirrup dominates the behavior, and as stirrup spacing increases, WFC determines the behavior. Finally, while the WFC content for bending RCBs increases the ability at the maximum level for the range of 20 % 30 %, it can be said that the optimum WFC content for shear RCBs is 20 %. The experimental results were obtained with the prediction of ACI-318 and the reason for the difference between the expected and actual values can be explained in detail.
  • Küçük Resim Yok
    Öğe
    Nonlinear Inelastic Stability Behavior of High-Strength Stainless Steel I-Beams with Sinusoidal Web Openings
    (World Scientific Publ Co Pte Ltd, 2023) de Carvalho, Adriano Silva; dos Santos, Vinicius; Rossi, Alexandre; Martins, Carlos Humberto; Ozkilic, Yasin Onuralp
    Perforated beams can bring countless benefits compared to traditional plain-webbed beams. However, steel beams with sequential web openings are more susceptible to instabilities, and special care must be taken in a design concerning the failure modes these structures can present. The study presented herein explicitly dealt with the stability behavior of perforated beams with sinusoidal openings. This type of perforated member features smooth-lined openings constructed from a single thermal cut in conventional plain-webbed steel profiles. A broad study was carried out through numerical simulation using the ABAQUS software, in which perforated profiles manufactured with S600E high-strength stainless steel were studied. The use of high-strength steels in perforated profiles is a little explored topic in the literature, despite having a significant impact on the behavior of these elements. With the study carried out, a broad overview of the stability behavior of these members was obtained, especially concerning global stability. A total of 5940 FE models were developed, considering the application of different types of loads. In these models, linear buckling analysis (LBA) and geometrically and materially nonlinear analysis with imperfections (GMNIA) were performed. The results obtained were compared with international design codes, and it was found that some codes fail to represent the behavior of members that present lateral-distortional buckling (LDB) and interactions between local and global failure modes. This behavior is a significant design concern since the studied members had high yield strength, making them more susceptible to interaction-governed failure modes than usual-yield strength members. Additionally, the study found that some design codes do not accurately represent the behavior of members loaded outside the shear center due to the destabilizing effect of loading on these structures.
  • Küçük Resim Yok
    Öğe
    Use of waste steel fibers from CNC scraps in shear-deficient reinforced concrete beams
    (Techno-Press, 2023) Kalkan, Ilker; Ozkilic, Yasin Onuralp; Aksoylu, Ceyhun; Mydin, Md Azree Othuman; Martins, Carlos Humberto; Hakeem, Ibrahim Y.; Isik, Ercan
    The present paper summarizes the results of an experimental program on the influence of using waste lathe scraps in the concrete mixture on the shear behavior of RC beams with different amounts of shear reinforcement. Three different volumetric ratios (1, 2 and %3) for the scraps and three different stirrup spacings (160, 200 and 270 mm) were adopted in the tests. The shear span-to-depth ratios of the beams were 2.67 and the stirrup spacing exceeded the maximum spacing limit in the building codes to unfold the contribution of lathe scraps to the shear resistances of shear-deficient beams, subject to shear-dominated failure (shear-tension). The experiments depicted that the lathe scraps have a pronounced contribution to the shear strength and load-deflection behavior of RC beams with widely-spaced stirrups. Namely, with the addition of 1%, 2% and 3% waste lathe scraps, the load-bearing capacity escalated by 9.1%, 21.8% and 32.8%, respectively, compared to the reference beam. On the other hand, the contribution of the lathe scraps to the load capacity decreases with decreasing stirrup spacing, since the closely-spaced stirrups bear the shear stresses and render the contribution of the scraps to shear resistance insignificant. The load capacity, deformation ductility index (DDI) and modulus of toughness (MOT) values of the beams were shown to increase with the volumetric fraction of scraps if the stirrups are spaced at about two times the beam depth. For the specimens with a stirrup spacing of about the beam depth, the scraps were found to have no considerable contribution to the load capacity and the deformation capacity beyond the ultimate load. In other words, for lathe scrap contents of 1-3%, the DDI values increased by 5-23% and the MOT values by 63.5-165% with respect to the reference beam with a stirrup spacing of 270 mm. The influence of the lathe scraps to the DDI and MOT values were rather limited and even sometimes negative for the stirrup spacing values of 160 and 200 mm.
  • Küçük Resim Yok
    Öğe
    Use of waste steel fibers from CNC scraps in shear-deficient reinforced concrete beams
    (Techno-Press, 2023) Kalkan, Ilker; Ozkilic, Yasin Onuralp; Aksoylu, Ceyhun; Mydin, Md Azree Othuman; Martins, Carlos Humberto; Hakeem, Ibrahim Y.; Isik, Ercan
    The present paper summarizes the results of an experimental program on the influence of using waste lathe scraps in the concrete mixture on the shear behavior of RC beams with different amounts of shear reinforcement. Three different volumetric ratios (1, 2 and %3) for the scraps and three different stirrup spacings (160, 200 and 270 mm) were adopted in the tests. The shear span-to-depth ratios of the beams were 2.67 and the stirrup spacing exceeded the maximum spacing limit in the building codes to unfold the contribution of lathe scraps to the shear resistances of shear-deficient beams, subject to shear-dominated failure (shear-tension). The experiments depicted that the lathe scraps have a pronounced contribution to the shear strength and load-deflection behavior of RC beams with widely-spaced stirrups. Namely, with the addition of 1%, 2% and 3% waste lathe scraps, the load-bearing capacity escalated by 9.1%, 21.8% and 32.8%, respectively, compared to the reference beam. On the other hand, the contribution of the lathe scraps to the load capacity decreases with decreasing stirrup spacing, since the closely-spaced stirrups bear the shear stresses and render the contribution of the scraps to shear resistance insignificant. The load capacity, deformation ductility index (DDI) and modulus of toughness (MOT) values of the beams were shown to increase with the volumetric fraction of scraps if the stirrups are spaced at about two times the beam depth. For the specimens with a stirrup spacing of about the beam depth, the scraps were found to have no considerable contribution to the load capacity and the deformation capacity beyond the ultimate load. In other words, for lathe scrap contents of 1-3%, the DDI values increased by 5-23% and the MOT values by 63.5-165% with respect to the reference beam with a stirrup spacing of 270 mm. The influence of the lathe scraps to the DDI and MOT values were rather limited and even sometimes negative for the stirrup spacing values of 160 and 200 mm.