A carbon fiber reinforced steel beam was tested, which was subjected to cyclic loads of varying intensity during bending during glue hardening and periodically tested in static mode to determine the increase in stiffness. Tests have shown that adhesion occurs at higher loads, the adhesion strength decreases, and when the shear stress in the adhesive layer is exceeded, adhesion does not occur. The flexibility of the adhesive layer also reduces the cross-section characteristics, but by no more than 7%. Lap shear tests performed on samples cut from reinforced beams confirmed the results of bending tests, showing that the greatest decrease in adhesion strength occurs at the ends of the beams, where the sliding and shear stresses are greatest.

Keywords: carbon fiber reinforcement, cyclic load, adhesive joint strength, lap shear test

During the research, a new prestressing system was developed for carbon fiber reinforced polymer plates to reinforce damaged steel beams. A parametric analysis was performed using finite element modeling. The results showed that satisfactory amplification efficiency can be achieved using the new pre-voltage system. The prestressed carbon fiber significantly increased the performance when bending beams at the elastic and elastic-plastic stages due to the use of high-strength carbon fiber plates. In addition, as the pre-voltage level increased, the amplification efficiency increased. A simple increase in the area or modulus of elasticity of the carbon fiber plate slightly improved the hardening efficiency, while the simultaneous application of prestressing clearly increases the hardening efficiency.

Keywords: reinforcement, steel beam, prestressing, new system, carbon fiber plate