基于车辆荷载的锈损公路桥梁疲劳性能试验研究

采用湿盐砂锈蚀方法获得腐蚀环境钢筋混凝土劣化试件，选取与车辆荷载作用下公路桥梁实际承受的疲劳应力水平，通过8根锈蚀钢筋混凝土梁的弯曲疲劳试验，分析了锈蚀钢筋混凝土梁的疲劳破坏形态及应力水平和钢筋锈蚀率对梁疲劳性能的影响规律。试验结果表明，锈蚀梁的疲劳破坏形态为主筋脆性断裂；在设计应力水平作用下，疲劳加载满足规范200万次要求；在桥梁实际应力水平作用下，未锈蚀试验梁的平均疲劳寿命较规范值减少6.71%；锈蚀较严重的试验梁疲劳寿命较规范值减少13.57%，较同应力水平的未锈蚀梁疲劳寿命减少42.54%，锈蚀对试验梁的疲劳寿命影响显著。随着疲劳循环次数的增加，锈蚀梁钢筋内部出现疲劳损伤、抗弯刚度逐渐退化，混凝土残余应变累积，裂缝演变基本符合快速增加、稳定发展、急剧变化的“三阶段”发展规律。根据试验结果，建立S-N疲劳寿命方程，提出了锈蚀钢筋混凝土梁疲劳寿命计算方法，研究结果为桥梁结构疲劳性能评估提供理论依据。

Experimental study on fatigue performance of corroded highway bridges based on vehicle loading

Wet corroded sand specimens were used to obtain corroded reinforced concrete specimens. Targeted selection and the vehicle under the load of the bridge and the actual fatigue stress level. Through the bending fatigue test of eight corroded RC beams, the fatigue failure mode and the influence of the stress level and corrosion rate on the fatigue behavior of corroded RC beams are analyzed. The experimental results show that the fatigue failure model of the corroded beams is mainly the brittle fracture of the main ribs. Under the stress level of design, the fatigue load meets the requirements of 2 million times. Under the actual stress level of bridge, the average fatigue life of un-corroded test beam is reduced by 6.71% compared with the normal value. The fatigue life of the test beam with more serious corrosion is reduced by 13.57% compared with the standard value, and the fatigue life is reduced by 42.54% compared with the un-eroded beam under the same stress level. Corrosion has a significant effect on the fatigue life of the test beam. With the increase of the number of fatigue cycles, the fatigue damage, the gradual deterioration of the bending stiffness and the accumulation of residual strain of concrete in the corroded beam reinforce the internal structure of the corroded beam. The evolution of the fracture basically accords with the development of the “three stages” of rapid growth, steady development and rapid change. According to the test results, the fatigue life equation of S-N is established, and the calculation method of fatigue life of corroded RC beams is proposed. The results provide the theoretical basis for the assessment of fatigue properties of bridge structures.