Browsing by Author "Akyuz, U."

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Behaviour of Cfrp Confined Low Strength Concrete Columns Under Temperature Changes
(2012) Erdil, B.; Akyuz, U.; Yaman, I.O.
In this study, an experimental program was established to understand the behaviour of FRP-confined low strength cylindrical and square-section concrete columns under temperature changes. The experimental program was divided into four groups. First group of specimens were kept under room temperature and used as control specimens. In the second group, specimens were exposed to predetermined heating-cooling cycles in a specially designed environmental test chamber. Third group of specimens were placed in water, kept in the environmental test chamber, and subjected to the same heating-cooling cycles. In the last group, specimens were subjected to outdoor exposure in Ankara, Turkey. After the aging tests, specimens were tested under uniaxial compression to determine the change in their mechanical properties.
A Comparative Study of Force-Deformation Relationship of Frp-Confined Concrete Columns
(2011) Erdil, B.; Akyuz, U.; Yaman, I.O.; Irfanoglu, A.
In this study, the FRP-confined concrete models for prismatic members given in the ACI440.2R-08 and Turkish Earthquake Code (TEC2007) are compared with the experimental data taken from the literature. It is found that TEC2007 assumes only hardening behavior for concrete strengthened with FRP. Although ACI440.2R-08 assumes a hardening and softening behavior depending on the confinement-effectiveness, the limit separating the hardening and softening must be improved to predict the behavior well. The assumptions in these codes cannot predict the post-peak region of force-deformation curves because of the high factor of safeties. It is essential to understand the degree of confinement, confinement effectiveness and the resulting stress-strain relationship of a concrete strengthened with FRP.
Mechanical Behavior of Cfrp Confined Low Strength Concretes Subjected To Simultaneous Heating-Cooling Cycles and Sustained Loading
(Springer, 2012) Erdil, B.; Akyuz, U.; Yaman, I. O.
This study aims to present the mechanical behavior of carbon fiber reinforced polymers (CFRP) reinforced low strength cylindrical and prism concrete specimens under both heating-cooling cycles and sustained loading. Heating-cooling cycles range from -10 to 50A degrees C and the applied sustained load level is 40% of the ultimate strength of concrete. After 200 heating-cooling cycles and/or sustained load testing, specimens were tested to determine the mechanical behavior under uniaxial compression. The experimental test results show that heating-cooling cycles alone have insignificant effect on the mechanical properties of CFRP-wrapped specimens. However, as for simultaneous exposure of sustained loading and heating-cooling cycles the main difference is on the shape of the stress-strain diagram, in which the bilinear response becomes clear. The other difference is on the ultimate strain, which decreases up to 29 and 15% for cylindrical and prismatic specimens, respectively.