Characterization of AFRP Repair for Circular Hollow Steel Tubes with Stochastic Corrosion-Induced Imperfections under Axial Compression

Abstract

Abstract Corrosion-induced defects, often extensive and unavoidable in marine structures, significantly compromise structural performance, posing a substantial risk to safety. To investigate the residual axial compression strength of corroded circular hollow section (CHS) steel tubes and evaluate the reparative effects of composite patches, a feasibility analysis is conducted through verifying the axial compression performance of a corroded tube with uniformly distributed corrosion pits and a perfect tube strengthened by Aramid fiber-reinforced polymer (AFRP). Subsequently, mechanical responses of the corroded and AFRP-repaired tubes are studied, and parametric studies are undertaken to comprehensively evaluate the influence of the corrosion region, as well as the depths and densities of the corrosion pits. Consequently, critical damage modes of the AFRP patches are explored using a VUMAT subroutine developed based on Hashin failure and Yeh delamination damage criteria. Numerical predictions indicate that composite patches improve the structural residual strength, but not necessarily enhance the structural ductility under diverse failure patterns. In addition, AFRP patches are conductive to improve the structural overall load-bearing capacity through alleviating the local buckling or regional collapse. Moreover, fiber compression damage emerges as the dominant mode, significantly influenced by the mechanical properties of the putty agent. The premature failure of the putty initiates stress concentration, intensifies subcritical damage, aggravates critical damage, and expedites final failure.