Study On Bending Tribo-Corrosion-Fatigue Behavior Of Steel Wire Of Main Cable Of The Suspension Bridge

Bridge construction in our country has entered the span river and span sea era.The long-span multi-tower suspension Bridges are widely used because of their large span,strong load-bearing capacity,beautiful appearance and convenient erection.The main cable is the key load-bearing component,and its failure will cause the instability of suspension bridge structure or even collapse.In the service process,the suspension bridge is subjected to the coupling action of wind load,dead load(deck system,stiffened beam,main cable,etc.),live load(automobile load,etc.)and salt spray environment(Na Cl,etc.).These will lead to bending tribo-corrosion-fatigue behaviors of steel wire with different friction pairs at the main saddle.The bending tribocorrosion-fatigue behaviors will decrease the effective cross-sectional area and loadbearing capacity of the wire,and even seriously affect the load-bearing safety of the main cable.Therefore,it is of great significance to study the bending tribo-corrosionfatigue behaviors of main cable wire to improve the load-bearing safety and reliability of main cable and ensure the service reliability of suspension bridge.In this thesis,the finite element model of the main cable wire at the main saddle is constructed,and the tribo-fatigue parameters between the wires and the wire-saddle are obtained.The self-made bending tribo-corrosion-fatigue test rig is employed for the bending tribo-corrosion-fatigue test of steel wire with different friction pairs(between wire and saddle groove,parallel wires).The tribological properties(friction coefficient,wear mechanism,wear profile,volume loss,wear rate),corrosion resistance(polarization curve,electrochemical impedance spectrum),interaction between wear and corrosion and the influence of fatigue cycle,fatigue load and solution medium on the bending tribo-corrosion-fatigue behaviors with different friction pairs are revealed.The results show that the friction coefficient in pure water is higher than that in 3.5%Na Cl solution under different friction pairs.With the increase of fatigue cycle,the wear width,wear depth,cross-sectional failure area and total volume loss of fatigue wire increase.The wear rate between the wire and saddle groove decreases first and then tends to be stable as compared to decrease first and then increase gradually between steel wires.The wear mechanisms of fatigue wire in 3.5% Na Cl solution are abrasive wear,corrosion wear and fatigue wear as compared to abrasive wear and fatigue wear in ultrapure water.The wear width,wear depth,cross-sectional failure area,volume loss and wear rate of fatigue wire in different mediums increase and the corrosion resistance decreases with the increasing fatigue load.The interaction between corrosion and wear is enhanced with the increase of fatigue load,and the promoting effect of corrosion on wear is strengthened.The interaction between corrosion and wear is mainly synergistic under different friction pairs.