Fatigue failure behavior of corrosion water supply steel pipes with void around pipes under long-term service load coupling

Abstract

Corrosion and void are common defects in the walls and surroundings of water supply steel pipes. Understanding the fatigue failure behavior of steel pipes with combined corrosion and void defects under long-term service loads is essential for assessing their full-service life. This study conducted full-scale fatigue tests on water supply steel pipes with corrosion and void subjected to long-term traffic loads, earth pressure, internal pressure, and groundwater, using an indoor model box testing system. It was observed that the maximum Von Mises strain exhibited slow, rapid, and steady growth as traffic load cycles increased, with a fatigue life of approximately 71.04 million cycles. Subsequently, 3D detailed models of the steel pipe and fluid were established using ABAQUS 6.14–1 and FLUENT 16.0, respectively, and the structural-fluid dynamic coupling was solved through the MpCCI 4.4.2 multiphysics coupling platform. Using the validated FE model, the influence of corrosion length, width, and depth, as well as void position, length, and width, on the fatigue life of the steel pipe was analyzed. Additionally, the longitudinal bending moment and vertical displacement behavior of the pipe at fatigue failure were investigated. It was found that the fatigue life is lowest at the springline, 0.86 and 0.95 times that of the voids at the invert and crown, respectively. As void length, void width, and corrosion length increase from their minimum to maximum design values, the fatigue life of the steel pipe increases by 52%, 45%, and 16%, respectively. However, as corrosion width and depth increase from their minimum to maximum design values, fatigue life decreases by 35% and 54%, respectively. At fatigue failure, the void at the springline results in the smallest longitudinal bending moments and vertical displacements. Both bending moments and displacements increase with increasing void length, width, and corrosion length, while they decrease with increasing corrosion width and depth.