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Review
. 2019 Jul 26;12(15):2390.
doi: 10.3390/ma12152390.

Assessment of Standards and Codes Dedicated to CFRP Confinement of RC Columns

Stefan Kaeseberg  1 , Dennis Messerer  2 , Klaus Holschemacher  3
Affiliations
Review

Assessment of Standards and Codes Dedicated to CFRP Confinement of RC Columns

Stefan Kaeseberg et al. Materials (Basel). .

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.

Keywords: CFRP; columns; confinement; load bearing capacity; reinforced concrete; standards.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Stress-strain model for FRP confined concrete according to Lam and Teng [15].
Figure 2
Figure 2
Design procedure for a fiber reinforced polymer (FRP) confined reinforced concrete (RC) column subjected to combined compression and bending.
Figure 3
Figure 3
The partial safety factor γj introduced in the designated standard or guideline and the corresponding coefficient of variation Vx.
Figure 4
Figure 4
Confinement pressure flj depicted as a function of CFRP rupture strain εFRP (derived from flat coupon tests) when the modulus of the composite material is Ej = 200 GPa.
Figure 5
Figure 5
Confinement pressure flj depicted as a function of CFRP rupture strain εFRP (derived from flat coupon tests) when the modulus of the composite material is Ej = 600 GPa.
Figure 6
Figure 6
Effect of εccu on the column behavior under combined axial compression and bending [36]. (a) Model representation of a column exposed to normal force and bending moment. (b) Curvature and forces in Section a.
Figure 7
Figure 7
Stress-strain distribution of a CFRP confined RC column at the balance point, according to the considered codes and guidelines.
Figure 8
Figure 8
Values for kε determined from tests with different CFRP materials, calculated characteristic values kεk (according to EN 1990), and partial safety factors γj (according to fib Bulletin 80 [27]).
See this image and copyright information in PMC

References

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