混凝土矮箱梁桥疲劳性能监测与评估

采用动态称重(WIM)技术对陕西省省道S305线崾岘中桥进行交通荷载监测，分析得出了适合陕西省混凝土桥梁的标准疲劳车模型。采用动应变监测技术对混凝土矮箱梁关键部位进行长期动应变监测，获得了运营状态下混凝土矮箱梁的实测应力谱；运用Miner线性准则和应力幅 循环次数曲线对结构进行疲劳寿命评估；对超载情况下混凝土矮箱梁的疲劳寿命进行了分析。结果表明:在目前交通荷载作用下，混凝土矮箱梁的疲劳寿命为5 120年，考虑腐蚀疲劳的因素后疲劳寿命降至254年；当超载车辆比例低于1%时，超载对桥梁结构的疲劳寿命影响很小；当超载车辆比例达到10%时，结构的疲劳寿命随着超载率的提高而显著降低；该研究成果可为崾岘中桥未来维护管理提供技术支撑，同时为同类型其他桥梁的疲劳寿命评估提供参考。

Fatigue Performance Monitoring and Assessment for Concrete Low-box Girder Bridge

Weigh-in-motion (WIM) system was adopted to monitor the fatigue loads of Yaoxian medium bridge in Shaanxi provincial road S305, and standard fatigue vehicle model for concrete bridges in Shaanxi province was determined based on recorded data. Dynamic strain monitoring technique was adopted to conduct continuous strain monitoring of key positions on concrete low box girder, acquiring the real stress spectrum under service situation. Moreover, the fatigue life assessment of structures was carried out by using Miner linear criterion and stress amplitude cycle number curve. The results show that the fatigue life of concrete low box birder is 5 120 years under the present traffic load, and the fatigue life decreases to 254 years when taking into consideration of fatigue corrosion. Under overload situation, when the ratio of overload vehicle belows 1%, the influence is little; when the ratio reaches 10%, the fatigue life of structures will decrease sharply with increasing of the overload ratio. Research achievement can provide technical support for the future management and maintenance of Yaoxian medium bridge, and provide reference for fatigue life assessment of other similar bridges.