服役斜拉索疲劳状态的全场域在线实时监测与智慧感知

Whole-field Online Real-time Monitoring and Intelligent Perception of Fatigue States of Cables in Service

为了能对斜拉桥拉索的服役性能进行更为准确和及时的评估,提出了一套服役期拉索疲劳状态评估的全场域实时监测与智慧感知技术方案。该方案首先给出了基于拉索横向动刚度分析理论的拉索全场域、全应力时程的实时感知方法,其次利用Miner线性疲劳累计损伤理论评估拉索全场域的疲劳损伤状态;最后,将其应用于一座斜拉桥的拉索的振动监测信息处理上,证明了所建议的技术和方案可实现服役拉索疲劳状态的全场域实时监测和智慧感知。具体结论如下:在拉索疲劳应力幅的组成中,由外荷载引起的索端位移产生的索力变化所产生的应力占比最大,当拉索发生较大幅度振动时,振动附加索力变化产生的应力也不可忽略;通过对拉索疲劳应力幅的统计分析发现,与长索相比,短索对外荷载更加敏感,通常会引起更大和更频繁的索力变化,故在斜拉桥拉索疲劳分析中,应对短索给予更多的关注;在拉索疲劳损伤分析时,弯曲应力和腐蚀的影响非常显著,若要使拉索疲劳寿命的预测更接近实际工程情况,需要考虑弯曲应力和腐蚀的影响;在应力幅较大的区域,对应循环次数较少,但拉索疲劳损伤度较大,在应力幅较小的区域,虽然循环次数较多,但拉索的疲劳损伤度较小,所以,在疲劳分析中,拉索应力幅比循环次数更值得关注。

To evaluate the service performance of cables in cable-stayed bridges accurately and in a timely manner,a whole-field real-time monitoring and intelligent perception technology scheme is proposed for the fatigue state evaluation of cables in service.First,based on the transverse dynamic stiffness theory of cables,a method is proposed for the real-time perception of the whole-field and full-stress time history of a cable.Furthermore,based on Miner’s linear fatigue damage accumulation theory,this paper proposes a whole-field fatigue damage state assessment method.The proposed method was applied to the vibration monitoring data processing of cables on a real bridge.The results indicate that the proposed technology and scheme can realize the real-time monitoring and intelligent perception of the fatigue state of service cables in the whole-field.In the fatigue-stress amplitude of the cables,the stress produced by the tension change caused by the external load is the main component.When the cable vibrates significantly,the stress caused by changes in additional stress should not be neglected.Through the statistical analysis of cable fatigue stress amplitude,it was determined that in cable-stayed bridges,compared to long cables,short cables are more sensitive to external loads and typically experience larger and more frequent tension changes.Therefore,more attention should be paid to short cables when analyzing cable fatigue.Bending stress and corrosion are also significant in the analysis of cable fatigue damage.To make the prediction of cable fatigue life closer to real engineering scenarios,the influence of these two factors should be considered.Additionally,in regions with a large stress amplitude,although the cycle number is lower,the fatigue damage degree of the cables is greater,whereas in regions with a small stress amplitude,although the cycle number is higher,the fatigue damage degree of the cables is smaller.Therefore,the stress amplitude of a cable is more important than the number of cycles.