Development of a novel anchorage and tensioning system for strengthening steel beams with unbonded prestressed CFRP plates

Carbon fiber reinforced polymer (CFRP) plates have been widely used in the strengthening and retrofitting of engineering structures due to their excellent mechanical properties. Applying a prestress to a CFRP plate is an effective solution for increasing its strengthening effectiveness, whereas the high-efficient anchorage and convenient tensioning of the CFRP plate are critical issues in practical applications. A novel anchorage and tensioning system for the prestressed CFRP plate was developed in this study. The space requirement at the end of structural elements can be significantly reduced by using this novel system. A finite element analysis was first conducted on the CFRP plate-anchor assembly to investigate the main factors affecting the anchorage performance. Based on the FE results, the final geometric sizes of the anchors were determined. Tensioning tests of the CFRP plate-anchor assemblies were carried out to verify the anchorage efficiency. The test results indicated that the CFRP plate could be loaded to fracture completely, and the anchorage system exhibited excellent anchorage efficiency. Finally, this system was used in the flexural strengthening of steel beams with unbonded prestressed CFRP plates. The flexural test results demonstrated that this system was effective for enhancing the flexural behavior of steel beams. The unbonded prestressed CFRP plate could obviously increase the load-carrying capacity and reduce the deflection of steel beams. The developed novel anchorage and tensioning system was proven to be feasible and applicable for flexural strengthening of steel beams with unbonded prestressed CFRP plates. •A novel anchorage and tensioning system for prestressed CFRP plates was developed.•The optimal design was conducted based on the FE modelling to determine the geometric sizes of the anchors.•The CFRP plate could be loaded to fracture completely, and the anchorage system exhibited excellent anchorage efficiency.•The anchorage and tensioning system was effective for enhancing the flexural behavior of steel beams.