既有混凝土桥梁疲劳寿命与使用安全评估

Fatigue Life and Service Safety Assessment for Existing Concrete Bridges

基于混凝土桥梁疲劳失效机理,提出了基于S-N曲线和断裂力学的混凝土桥梁疲劳寿命与使用安全评估方法。采用现场监测数据,对七狼窝黄河大桥T型梁受拉主筋的疲劳寿命进行了估算。结果表明:采用Miner疲劳损伤线性累积准则能够较好预测混凝土梁的疲劳使用寿命,考虑腐蚀影响时钢筋腐蚀疲劳寿命降低显著,仅为93年;按断裂力学模型估算的七狼窝黄河大桥T型梁受拉主筋的疲劳寿命约为280年,但计算结果未考虑腐蚀对疲劳寿命的影响,在进一步研究中应计入腐蚀对钢筋断裂力学参数的影响;混凝土桥梁疲劳寿命评估结果为既有桥梁科学维护决策提供了技术支撑。

Considering the fatigue mechanism of concrete bridges under fatigue loads, the fatigue life and service safety assessment methods for existing concrete bridges were proposed based on S-N curve and fracture mechanics approach. Using the monitoring data, the fatigue life of rebar in T shape RC deck girder of Qilangwo Yellow River Bridge was evaluated. The evaluation results show that the S-N curve assessment method can predict the fatigue life of rebar well, and the fatigue life, which will decrease quickly considering the corrosion effect, is only 93 years. The fatigue life of deck girder for Qilangwo Yellow River Bridge calculated by fracture mechanics model is about 280 years without corrosion effect. In further research, the corrosion effect on crack growth parameters should be considered. The fatigue evaluation results provide a technical support for the scientific maintenance strategy of existing bridges.