Carbon fiber reinforced polymer strengthened reinforced concrete square columns under pre-existing eccentric loads

Kian N., Farzam M., Rezaie Oshtolagh M.

ADVANCES IN STRUCTURAL ENGINEERING, 2021 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume:
  • Publication Date: 2021
  • Doi Number: 10.1177/13694332211029730
  • Keywords: Pre-existing load condition, CFRP layer, strengthening, RC Column, tension-controlled region, AXIAL-FLEXURAL INTERACTION, FRP-CONFINED CONCRETE, STRESS-STRAIN MODEL, RC COLUMNS, CFRP COMPOSITES, BEHAVIOR, PERFORMANCE


Numerous experimental studies have been conducted on the behavior of strengthened columns, mostly with glued layers of FRP before load application, and rarely under the pre-existing load. Results confirm a good efficiency of strengthening in the compression-controlled region of the columns, as mentioned in design codes and guides such as ACI 440.2R-17. However, their behavior in the tension-controlled region is still a challenging subject. Moreover, when the eccentricity is large enough, the efficiency of the strengthening method needs more attention. This study aimed at strengthening six RC columns in the tension-controlled region under the pre-existing load condition. Furthermore, tested specimens were verified using a nonlinear finite element analysis performed in ATENA software. Moreover, some identical strengthened specimens, which were not subjected to pre-existing load during strengthening, were modeled to capture the effect of pre-existing loads. The results of the analyses were in good agreement with experimental data. Comparison of numerical results obtained for columns strengthened without pre-existing load, and under pre-existing load showed that pre-existing loading significantly reduced the efficiency of FRP jacketing. Also, assuming a linear variation of confinement pressure in the tension-controlled region of the interaction diagram results in good agreement with attained results.