腐蚀对风车联合作用下斜拉桥拉索 疲劳可靠性的影响分析

为探讨腐蚀对随机交通和风载联合作用下斜拉索疲劳可靠性的影响规律和机理,通过拉索高强钢丝的加速腐蚀和疲劳试验,提出了考虑腐蚀的斜拉索疲劳抗力模型;基于线性累积损伤准则,建立了考虑腐蚀影响的风车联合作用下拉索疲劳可靠性的分析方法和流程;依托工程实例,分析了腐蚀等级和时变腐蚀对拉索疲劳可靠性的影响.结果表明:随腐蚀加剧拉索动态疲劳可靠指标下降速率增大;等级达到Ⅲ级及以上的腐蚀对拉索疲劳可靠寿命影响显著,尤其对于靠近桥塔及辅助墩处拉索;Ⅳ级和Ⅴ级腐蚀时拉索疲劳寿命相对无腐蚀状况降幅最大分别达24%和44%;相对完好状况,时变腐蚀影响下拉索的动态疲劳可靠指标下降更为迅速,且降幅明显大于仅考虑腐蚀分级的状况.

Analysis of Corrosion Effect on Fatigue Reliability of Stay Cables under Traffic and Wind

To study the effect of corrosion on fatigue reliability of stay cables under random traffic and wind load, the fatigue life model for stayed cables considering corrosion is firstly built up based on accelerated corrosion and fatigue performance experimental results for high strength steel wires. Secondly, the fatigue reliability analysis procedure for stay cables under various corrosion levels and time-varying corrosion is established based on the linear cumulative damage theory considering the combination of vehicle and wind load. Finally, the influence of corrosion on fatigue reliability for the stay cable is studied considering the random traffic and wind combined action for a large span cable-stayed bridge. The research results indicate that the down rate of time-varying fatigue reliability increases with the aggravation of corrosion; the corrosion effect on fatigue becomes appreciable when corrosion is higher than level III, particularly for the cables closing to pylon and auxiliary piers; the maximum decreasing amplitude of cable fatigue life are 24% and 44% when corrosion condition changes from zero to level IV and V, respectively; the decrease of time-varying fatigue reliability index under time-varying corrosion is obviously larger than that just corresponding to corrosion level.