| As the main load-bearing structures of modern cable-stayed bridges, consideringthe live load and other variable affect, the cable system in service process is always incomplex stress state. Coupled with the effects of the corrosion factors in theenvironment, fatigue corrosion damage could cause the cable subjected to a doubledamage. A large number of domestic and international accidents about cable stayedbridges caused by cable rupture show that cable damage tends to cause a large change inthe stress state of the whole bridge structure, making the safety, durability and the life ofthe bridge reduced to a low level.Through accelerated salt spray corrosion experimentscarried indoor, this paper analyzes the corrosion weight loss of the steel under variousstress, elastic modulus, tensile strength and changes in various mechanical propertiesand note that the elongation is most sensitive, while other mechanical properties are lesssensitive or little changed in a small area. On the base of experiments carried outalready, by the means of microscopic damage mechanics, combined fracture mechanicsstrength criterion, this paper is to study environmental corrosion, stress corrosion andcorrosion fatigue characteristics of each mechanism, Conclude that "anode corrosiongalvanic cell reaction stress is a major mechanism of state under cross cable damage".Stay cable corrosion fatigue damage is mainly caused by corrosion pits on steelsurface, leading to the stress concentration, combined with hydrogen induced cracking.In this condition, the initiation cracks would be constantly formed and developed. Thispaper also study the application of corrosion fatigue crack growth threshold as thecriterion of transformation of pitting corrosion to crack; by numerical methods, acomprehensive analysis of the steel corrosion, surface pitting depth, shape and verticalnet spacing of pits on the steels effect on stress distribution and fatigue life. |
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