疲劳荷载与海水侵蚀作用下钢筋混凝土梁耐久性试验

沿海地区的钢筋混凝土桥梁结构在服役期间，受到疲劳荷载和氯离子侵蚀的综合作用，其使用寿命缩短。为模拟桥梁的实际工作状态,首先对钢筋混凝土梁施加疲劳荷载20万次(疲劳荷载上限分别为0.16 P _u、0.24P _u、0.32P _u、0.40P _u，P _u为梁受弯极限荷载),然后经历海水浸泡和空气环境干湿循环100 d,最后静力加载获得钢筋混凝土梁受弯承载力。共完成5组10根钢筋混凝土梁试验。研究结果表明：在疲劳荷载上限不大于0.24P _u时，试件性能劣化不明显；疲劳荷载上限大于0.24P _u时，梁试件的初始刚度、屈服荷载和极限荷载随着疲劳荷载上限的增大而快速降低;当疲劳荷载上限为0.40P _u时，梁试件的初始刚度、屈服荷载和极限荷载分别降低51.80%、21.78%、15.07%。

Durability experiment of reinforced concrete beam under combined actions of seawater corrosion and fatigue loading

During the service life of the coastal reinforced concrete bridge structure, its lifetime can be shortened due to the combined action of fatigue loading and erosive effect of chloride ion. First, different fatigue loading conditions, with peak fatigue loads up to 16%, 24%, 32% and 40% of the ultimate load, were applied on the specimens 200 000 times. Then the specimens were eroded with seawater for 100 days. Second, the deterioration law of the flexural capacity of reinforced concrete beam was studied. Ten beam specimens were divided into five groups and tested. According to the experimental results, it is concluded that there is no significant decrease in mechanical properties of beams when the peak fatigue load is not more than 24% of the ultimate load; the initial stiffness, the ultimate load and yield load of the beam will decrease with the increase of peak fatigue load exceeding 24% of the ultimate load; the initial stiffness, ultimate load and yield load will decrease by 51.80%, 21.78% and 15.07% respectively compared with the reference group when peak fatigue load reaches 40% of the ultimate load.