Abstract
Reinforced concrete (RC) columns are often placed under confinement to increase their strength and ductility. Carbon fiber reinforced polymer (CFRP) materials have recently been recognized as favorable confinement systems. At present, a number of national standards and codes dedicated to the design of concrete components strengthened with CFRP in general and CFRP confinement in particular are available. These sets of rules provide design equations for confined reinforced concrete columns with circular and rectangular cross sections. Most of the standards and codes exhibit significant differences, including the used predictive models, limitations, observed effects and covered loading conditions. In this paper, five international standards and design guidelines are introduced and discussed. The purpose is to present a constructive and critical assessment of the state-of-the-art design methodologies available for CFRP confined RC columns and to discuss effects not previously considered properly. Therefore, some recent research efforts and findings from the Leipzig University of Applied Sciences are also introduced. The obtained data is used for a comparative study of the guideline predictive equations. Furthermore, it is shown that some new findings concerning the rupture strength and the maximum strength plus accompanying axial strain of a CFRP confined column are suitable to improve the current guidelines.
Highlights
Confinement is generally applied to concrete members in compression to increase their strength and ductility
Should beItnoted thatbethis paper is limited to the application of carbon fiber reinforced fiber reinforced polymers (CFRP)
In American Concrete Institute (ACI) 440, kε is recommended as 0.55, and in the Chinese code (CFRP) as well as in the German guideline, kε is assumed to be 0.50
Summary
Confinement is generally applied to concrete members in compression to increase their strength and ductility. Proper confinement can provide significant strength enhancement for members subjected to combined confinementand canflexure provide significant strength for members subjected to material combined compression as well. For this case, a enhancement model is necessary to describe the entire compression and flexure as well. A stress-strain (σc -εc ) material curve behavior of confined concrete under compressive stress. ModulusLam of elasticity, and εt is the transition the where Ecurve parabolic and the straight-line and Teng’s stress-strain model is between illustrated parabolic curve and the straight-line second portion.
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