Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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Article Citation - WoS: 10Citation - Scopus: 11Numerical Investigation on the Behavior of Reinforced Concrete Slabs Strengthened With Carbon Fiber Textile Reinforcement Under Impact Loads(Elsevier, 2022) Batarlar, Baturay; Saatcı, SelçukIn this study, impact load performance of reinforced concrete members strengthened with carbon fiber textile reinforcement (CFTR) was investigated through numerical simulations. In the first phase of the study, a finite element model was set up to model reinforced concrete slabs of 1500 × 1500 × 200 mm in dimensions, strengthened with CFTR and subjected to multiple impact loads, using software LS-DYNA. This model was validated against experimental data available in the literature and basic modeling parameters, such as material model selection, mesh size, and erosion parameters for better accuracy were determined. In the second phase of the study, a numerical parametric study was conducted using the validated model to reveal the effects of steel and textile reinforcement ratio, slab thickness, striker mass, size, and velocity on the behavior of steel-reinforced concrete slabs strengthened using CFTR. As a result of the study, it was found that CFTR was effective in limiting the peak and residual displacements in reinforced concrete slabs subjected to multiple impacts at the middle. Among 220 mm thick specimens, for the same steel reinforcement ratio, a higher CFTR ratio resulted in lower peak and residual displacement levels after the third impact. On the other hand, when 8 mm diameter steel reinforcement was varied from 100 mm to 200 mm spacing, it was found that steel reinforcement ratio was the dominant factor on the impact behavior over the CFTR ratio. CFTR strengthening was particularly more effective when the members displayed a global response instead of a local one, such as low-velocity high-mass impact loading or in the cases where the striker had a larger diameter. Similarly, thickness was also found to be a major factor on the effectiveness of CFTR. When thickness of the slab was varied from 50 mm to 300 mm, CFTR's effect was found to be more pronounced for thinner slabs in preventing perforation and limiting peak and residual displacements. However, for 200 and 300 mm thick slabs, CFTR did not have a significant effect since local punching behavior was dominant in these slabs and CFTR was not effective in this shear mechanism.Article Citation - WoS: 8Citation - Scopus: 9Çelik Fiber Katkılı Etriyesiz Betonarme Kirişlerin Davranışı(Gazi Üniversitesi, 2017) Saatçi, Selçuk; Batarlar, BaturaySunulan çalışmada çelik fiber katkısının farklı boyuna donatı oranlarına sahip etriyesiz betonarme kirişlerineğilme davranışına olan etkileri deneysel ve analitik olarak incelenmiştir. Yapılan deneysel çalışmada düşükve yüksek boyuna donatı oranına sahip iki grup kiriş imal edilmiştir. Her bir gruptaki kirişlerhacimce %0, %0,5, %1,0 ve %1,5 çelik fiber oranına sahip olup toplam sekiz kiriş açıklık ortasına uygulananyük altında test edilmiştir. Düşük boyuna donatı oranına sahip kirişlerde çelik fiber katkısı eğilme kapasitesini %50'ye yakın oranlarda arttırmış, ancak deformasyonların tek bir çatlakta toplanması sebebiyleboyuna donatıda kopmaya yol açarak çelik fiber katkısız kirişe göre daha az yerdeğiştirme yapmasına sebepolmuştur. Yüksek boyuna donatı oranına sahip kirişlerde ise çelik fiber katkısı etriye görevi görerek çelikfiber katkısı olmaması durumunda gevrek eğik çekme göçmesi gösteren kirişlerin sünek eğilme göçmesigöstermelerini sağlamıştır. Her iki grupta çelik fiber oranının arttırılması çatlak dağılımını etkilemeklebirlikte davranışta önemli bir farklılığa yol açmamıştır. Kirişler analitik yöntemlerle modellendiğindeliteratürde yaygın kullanılan ve çatlakta çelik fiberlerin taşıdığı çekme gerilmesini sabit kabul edenyaklaşımın güvenli tarafta olmakla birlikte eğilme kapasitesinin olduğundan düşük hesaplanmasına yolaçtığı, çekme gerilmelerini çatlak genişliği ile ilişkilendiren daha hassas modellerin daha iyi sonuçverebilecekleri görülmüştürArticle Citation - WoS: 2Citation - Scopus: 1Çelik Fiber Katkısının Farklı Boyuna Donatı Oranına Sahip Betonarme Döşemelerin Zımbalama Davranışı Üzerinde Etkileri(Gazi Üniversitesi, 2019) Saatçi, Selçuk; Yaşayanlar, Süleyman; Yaşayanlar, Yonca; Batarlar, BaturayIn this study, reinforced concrete slabs in two groups, having 0.004 (D1 series) and 0.002 (D2 series) longitudinal reinforcement ratios in two orthogonal directions, were cast with concrete mixes containing 0%, 0.5%, 1% and 1.5% steel fiber ratios in volume. Slabs were 2150x2150x150 mm in dimensions. Eight slabs were tested in total under static loads. For slabs without steel fibers, the slab with higher reinforcement ratio showed punching failure before the yielding of longitudinal bars, whereas the slab with lower reinforcement ratio displayed a significantly higher ductility before final punching failure. Addition of steel fibers increased the punching load capacity up to two times. However, although addition of steel fibers also increased the maximum displacements in D1 series slabs, it did not make any significant effect on the maximum displacements of D2 series slabs. Maximum displacements were still controlled by the yielding of longitudinal reinforcement. Increasing the steel fiber ratio increased both the punching capacity and the maximum displacements in D1 series slabs, but it did not make a significant difference in behavior of D2 series beyond 1% fiber ratio. An analytical study of the test specimens were also performed using Critical Shear Crack Theory and based on comparisons of experimental and analytical results some improvements in the model were proposed. © 2019 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved.