Experimental and analytical investigation of T-beams retrofitted through the external post-tensioning using steel and various FRP strands

Abstract

This study aimed to scrutinize the potential benefits of using fiber-reinforced polymer (FRP) materials as unbonded strands in post-tensioning systems for reinforced concrete (RC) flexural members. The research meticulously evaluated the influence of these FRP materials on global and local response levels. To this end, four-point loading tests were performed on T-beam specimens, and the experimental results were compared with numerical predictions. The study also incorporated insights from previous research on external post-tensioning variables. The results of this study, with their practical implications, demonstrate a strengthening technique that significantly enhances the load-carrying capacity at ultimate and yielding points, as well as the crack initiation load of non-strengthened specimens. The strengthening technique also significantly influences deflection during yielding and maximum loads and plays a crucial role in restoring deflection after unloading. However, it is essential to note that strengthening with external post-tensioning does reduce the member’s ductility. The choice of materials also emerges as a significant factor that leads to noticeable differences in crack widths and distribution among the specimens. These practical findings hold considerable importance and offer valuable insights into the potential use of FRP materials in post-tensioning systems for RC flexural members.