Master Degree / Yüksek Lisans Tezleri
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Master Thesis Bending Behavior of Hybrid Fiber Reinforced Concrete Beams(Izmir Institute of Technology, 2020) Aloui, Sarra; Saatcı, Selçuk; Aloui, Sarra; Saatçi, Selçuk; 03.03. Department of Civil Engineering; 01. Izmir Institute of Technology; 03. Faculty of EngineeringFiber reinforced concrete is widely used in various applications in concrete members. In this study, effect of fiber hybridization, using different types of fibers in concrete mix, on the bending behavior of concrete beams was investigated. For this purpose, eight beam specimens, 2500x500x50 mm in dimension, were cast in pairs with four different steel fiber content. One of the two specimens with the same steel fiber content had additional Polyvinyl Alcohol (PVA) fibers. The specimens were first tested under three-point bending. After these tests, failed specimens, which had a single crack at the midspan, were broken into two halves and the half with no visible damage was tested again under four-point loading to obtain the behavior for a constant moment region.The ultimate strength and the load-displacement behaviorwas investigated for each specimen. It was seen that fiber hybridization obtained by addition of PVA had an adverse effect for three-point bending tests. Specimens with additional PVA fibers had a lower ultimate load and deflection capacity compared to specimens with only steel fibers. However, fiber hybridization had a positive effect for same specimens under four-point bending test. It was concluded that hybridization of steel and PVA fibers had a positive effect on the bending behavior for loading conditions that result in a uniform moment distribution. However, for cases where a single crack dominates the behavior, such as a three-point bending case, hybrid fibers were not as effective or even had an adverse effect.Master Thesis Mechanical Behavior of Hybrid Fiber Reinforces Concrete Under Direct Tension(Izmir Institute of Technology, 2020) Çetin, Fatma Şirin; Saatcı, Selçuk; Erdem, Tahir Kemal; Saatçi, Selçuk; Erdem, Tahir Kemal; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyUsing different fiber types together, called hybrid fiber reinforced concrete, may cause a mutual synergic response between fiber matrixes. Due to these synergic effects of different fiber combinations, the mechanical behavior of concrete may perform differently than single fiber reinforced concrete. In this study, the effects of fiber hybridization in the direct tension behavior of concrete mixtures obtained by using three different types of steel fiber and polyvinyl alcohol (PVA) fiber were investigated. In this scope, total of 50 dog bone shaped, notched specimens were cast for 10 different mixtures and tested under direct tension. Average tensile stress-crack width responses of concrete specimens were investigated. It was found that the addition of PVA fiber to 35 mm long single hook end and 60 mm long double hook end steel fiber mixtures with a volume ratio of 0.75% did not considerably change the tensile behavior post cracking. As a result of adding PVA fibers to 60 mm single hook steel fiber mixtures with a volume ratio of 1.25%, cracking stresses were decreased and post cracking behavior was adversely affected. Addition of PVA fibers to 60 mm single hook steel fiber mixture with 0.75% volumetric ratio was found to increase post cracking stress levels.