Test Study And Calculation On High-strength Concrete Columns Confined By CFRP Under Uniaxial Loading

The rehabilitation and strengthening of insufficiently strong or damaged RC structures by means of externally bonded carbon fiber reinforced plastic (CFRP) sheets has received a great attention in the past decade in China. The results corresponding have been drawn a good many, however, most researches were concentrated on the normal RC members. Studies on high-strength RC members have been very limited. Combining with the research program of National natural science foundation of china and Liaoning province transportation bureau, a comprehensive investigation of the behavior of high-strength RC columns strengthened with externally bonded CFRP has been conducted. The objectives of this study were listed as follows:1. Theoretical analyses were carried out after an experimental study of six high-strength concrete square columns strengthened with CFRP under long-term sustained loading was conducted. The comparison between the calculation results based on the ACI209 (1992) specifications and test results show a basically agreement.2. Twenty four square columns reinforced with CFRP were tested experimentally under axial load to evaluate their capacity and ductility ability. Four parameters in this program which include the reinforcement ratio, the reinforcement mode, the spacing interval and width of straps were taken into account. The effects of those parameters on failure mechanisms, strength enhancement, and section stiffness were analyzed. It is shown that the application of CFRP can considerably increase the capacity and durability.3. According to the results of the test columns, theoretical analyses were carried out. Based on the test results and former documentations, a simplified stress-strain relationship model is provided.4. The behavior of CFRP-confined high-strength concrete square columns under uniaxial loading was analyzed by using the FEM method through the ANSYS program. The computing results are compared with test one. The comparison results show that the former can simulate the behavior of the columns with proper numerical model.