Repairing steel beams with different notch levels using composite materials

Abstract

Three notch levels were used to simulate fatigue crack propagation in the steel beams. The three levels are a complete loss of the tension flange of the simply supported beam adding 10.9% web loss; notch level #1, a complete loss of the flange adding 21.74% web loss; notch level #2 and a complete loss of flange adding 32.26% web loss; notch level #3. Nineteen beams were tested under two-point bending static loading up to failure. An intact beam and three notched beams with the three notch levels at the mid-span are the control specimens. Five specimens from each notch levels were repaired with different configurations. These configurations include attaching CFRP to the tension flange, covering 18 and 28 mm heights of the beam webs plus the flange, bonding CFRP to the flange and applying GFRP strips around the beam section and increasing the number of CFRP layers from two to three layers. A finite element (FE) program was used to simulate the beams. By wrapping CFRP to cover 18 mm web height, the difference between the peak load values of the repaired beams with notch level #1 and 2 was not increased than 1.8% while this difference reached 7.7% between repaired beams with notch level #1 and 3. Additionally, clear differences in mid-span deflection and energy absorption values between repaired beams with CFRP attached on the tension flange only and repaired beams with CFRP bonded on the flange and wrapping GFRP strips around the section of the beam were appeared in the cases of the three notch levels.