CFRP-patch repair characterization for compressive capacity recovery of perforated steel tubular members

Tubular steel structures commonly employed in offshore units may be subjected to severe corrosive processes, because of marine environmental conditions, resulting in significant material loss that may eventually disrupt or paralyze operations. Repairs in corroded structures entail entire or partial replacement of the damaged region by hot operations, such as cutting and welding, which raises the chance of accidents when large regions are involved. Cold works, such as patch repairs with composite materials, have proven viable in the oil and gas industry. However, there are no well-established processes for dimensioning the repair size, and there has been little research on its mechanical performance. A comprehensive research program based on carbon fiber was carried out to examine the composite patch repair of perforated steel tubular members. Samples of three composite materials were mechanically evaluated to estimate the repair thickness dimensioning, and double lap-shear tests were performed to determine the effective overlapping length of the CFRP-patch. A finite element model is proposed to perform numerical simulations of intact, damaged, and repaired tubular structures subjected to compressive loads, idealizing the damage as a circular cutout in half the sample's length with different sizes and various slenderness ratios. The repair thickness was then calculated numerically by comparing the maximum loads of repaired and intact tubes. The results indicate that a moderate repair thickness is sufficient to recover the intact tube compressive strength.