Behavior of CFRP confined concrete specimens under temperature cycles and sustained loads

Download
2012
Erdil, Barış
The application of carbon fiber reinforced polymers (CFRP) is one of the effective retrofitting and strengthening methods that is used worldwide and is starting to be used in Turkey as well because they have high strength and high modulus in the fiber direction, have very low coefficient of thermal expansion when compared to concrete and steel and are known not to corrode. Since FRPs are lightweight, their mass can be neglected when compared to concrete and steel. However, before proposing this material as an alternative for strengthening and retrofitting applications their long-term behavior should be understood because they are applied on to concrete by several layers of epoxy-based adhesives, which can be affected by change in humidity, temperature and load. Therefore, behavior of CFRP-strengthened structures in varying temperature and humidity conditions must be investigated. In this dissertation, behavior of CFRP confined cylindrical and prismatic concrete specimens having square cross-section were investigated under sustained compressive loads, dry and wet heating-cooling cycles, and outdoor exposures under direct sunlight, to determine the possible changes in their mechanical properties. Sustained loads were applied as the 40% and 50% of their confined axial load capacity. In addition to the sustained loads, specimens were subjected to 200 heating-cooling cycles between -10°C to 50°C. In order to understand the change in behavior of CFRP confined concrete specimens better, they were divided in six groups. A single effect was investigated in each group. After aging tests mechanical properties of the specimens were recorded via monotonic uniaxial loading. It was observed that temperature cycles had little effect on behavior but sustained loads changed the shape of the axial stress-strain diagram and resulted in a dramatic decrease in ultimate strain. Based on the test results and also using the data of similar studies available in the literature, strength and strain models considering the exposures as independent parameters were established and finally axial stress-strain curve was tried to be predicted.

Suggestions

Behavior and design of FRP bonded autoclaved aerated concrete beams
Tuncer, Erturk; Binici, Barış; Canbay, Erdem (2021-05-01)
Fiber Reinforced Polymers (FRPs) have advantages such as lightness, high strength, and suppressing corrosion risk. There is a vast amount of research on the FRP strengthening of reinforced concrete elements. However, the behavior of FRP bonded Autoclaved Aerated Concrete (AAC) beams has not been extensively investigated in the past. In this study, several experiments were conducted to explore the performance of FRP bonded AAC beams. In this scope, unidirectional single layer carbon and glass fiber laminates...
Experimental determination of tool wear in routing and trimming of CFRP composites
Peker, Zühal; Akkök, Metin; Kılıç, S. Engin; Department of Mechanical Engineering (2015)
In order to fulfill growing demand for lighter aircraft, Carbon fiber reinforced polymers (CFRP) have been developed, which differ from metals with regards to their machinability characteristics. The main problem in machining process is the damage caused by delamination of CFRP materials which need to be both cut and shorn of fibers at the same time, since they are remarkably abrasive in nature. This research aims at accessing the most appropriate cutting condition with less tool wear in routing and trimmin...
Effect of fiber type and concrete strength on the energy absorption capacity of fiber reinforced concrete plates under quasi-static bending
Mercan, Ali Macit; Yaman, İsmail Özgür; Department of Civil Engineering (2019)
With all the known solid advantages of concrete, it has also limitations in its mechanical properties, such as low ductility, tensile strength and energy absorption capacity/toughness. In order to eliminate or minimize these limitations, some developments have been worked up by introducing natural or artificial fibers into the concrete mixture. The main scope of this thesis is to observe the effect of different fiber types and dosages on the performance of two different concrete grades. Two steel fibers wit...
MECHANICAL PROPERTIES OF REPAIRED CARBON FIBER REINFORCED POLYMER COMPOSITES
Sonat, Emine Evren; Özerinç, Sezer; Department of Mechanical Engineering (2021-12-10)
Carbon fiber reinforced polymer (CFRP) composites are increasingly used in the aerospace industry due to their high specific strength compared to conventional metallic materials. However, a significant shortcoming of these composites is their increased susceptibility to damage. Structural repair is a common method to restore the load-carrying capacity of a damaged part when the damage size exceeds the pre-defined tolerances. Scarf and stepped bonded repair methods are the primary choice for cases that requi...
Effect of test methods on the performance of fiber reinforced concrete with different dosages and matrices
Hetemoğlu, Yalçın Oğuz; Yaman, İsmail Özgür; Department of Civil Engineering (2018)
Through the last few decades, the idea of adding fibers in to concrete has been quite improved, considering the significant contribution of fibers to the mechanical properties of concrete such as tensile strength, energy absorption capacity and ductility. As a result of many intensive research Fiber Reinforced Concrete (FRC) has become a high-tech material that ensures great performance yet needs efficient design and application. However, the lack of a universally accepted approach and standardized test met...
Citation Formats
B. Erdil, “Behavior of CFRP confined concrete specimens under temperature cycles and sustained loads,” Ph.D. - Doctoral Program, Middle East Technical University, 2012.