Effect of cross-sectional aspect ratio on the strength of CFRP-confined rectangular concrete columns

This paper presents the results of an experimental study on the behavior of axially loaded short rectangular columns that have been strengthened with carbon fiber-reinforced polymer (CFRP) wrap. Three series of uniaxial compression tests were conducted on 45 specimens. The parameters considered were the aspect ratio, defined as the depth (longer side)/width (shorter side) of the cross-section, and the number of CFRP layers. The behavior of the specimens in the axial and transverse directions was investigated. The test results clearly demonstrate that the strength gain in the confined concrete columns relative to the original unconfined columns, f c c / f c o decreases as the aspect ratio increases, until it becomes insignificant when the aspect ratio reaches 2. The test results are compared with the theoretical predictions of existing strength models and significant differences are found, indicating the need for further model development. A new model for the strength of FRP confined rectangular concrete columns is proposed, based on the test results from this work and results collected from the literature.