The longitudinal mechanical behavior of steel pipes with pitting corrosion under the coupling effect of complex service loads

Abstract

Corrosions on the outer walls stand as the primary cause of decreased structural integrity in steel water supply pipes. Pitting corrosion is identified as one of the most severe corrosion types. The failure risk of steel pipes with pitting corrosion significantly increases under the effects of complex service loads. In this study, full-scale tests of steel pipes with pitting corrosion on the outer wall under complex service loads were conducted. FE models capable of simulating the spatiotemporal interplay between the corroded steel pipe-soil structure and the pressurized fluid inside the pipe were developed. Comparative analysis was performed on the measured and simulated longitudinal strains and bending moments under complex operational loads for corroded and intact pipes. The impact of traffic loads, internal pressure, groundwater levels, and normalized corrosion parameters on the longitudinal Von Mises stress and bending moments of corroded steel pipes was investigated. The results indicate that, under standard corrosion parameters, the peak longitudinal Von Mises stress and positive bending moment at the crown of corroded pipe increase by 64.3 % and 397.3 %, respectively, compared to intact pipes. The corrosion depth has a more significant effect on the peak longitudinal Von Mises stress and positive bending moment than corrosion width and corrosion length. As the corrosion depth increases from 0.2 to 0.8, the peak longitudinal Von Mises stress and positive bending moment at the crown increase by 175.9 % and 193.4 %, respectively, while the negative bending moment is largely unaffected by corrosion geometric parameters. Increasing traffic loads from 0.4 MPa to 1.2 MPa results in increases of 23.3 %, 148.5 %, and 198.1 % in the peak longitudinal Von Mises stress, positive bending moment, and negative bending moment, respectively. Internal pressure increasing from 0.1 MPa to 1.0 MPa leads to increases of 328.8 % and 81.9 % in the peak longitudinal Von Mises stress and positive bending moment, respectively, with negligible changes in the negative bending moment. When the groundwater level rises from 600 mm below the bottom to 600 mm above the crown, the vertical displacement at the crown increases by 66.9 %.