Experimental and analytical study on fatigue strength and stress concentration of corroded bridge wires

Fatigue tests were conducted for corroded galvanized steel wires on three corrosion levels, showing that fatigue strength of corroded wires lowers as corrosion progresses. Deeper and severer corrosion pits seem to form in more condensed areas. Fatigue tests were then conducted for wire specimens wi th artificial pits whose sizes were decided by the measured corrosion pit data. Three different pit shapes were assumed: round, triangle and triangle with a notch. Fatigue strength of wires with triangle pit was lower than that with a round shape. Fatigue strength of wires with notched triangle further decreased. The pit shape seems to be a dominant factor to lower fatigue strength. Stress concentration factor at the sharp edge of pits were obtained by strain gauge measurement and 3D FEM analysis. Both methods showed that strain was almost same value and stress concentration is larger for sharper pit shapes, indicating that this is the major cause for decrease of fatigue strength.