销铰式索梁锚固结构传力机理及疲劳性能研究

Mechanical Behavior and Fatigue Performance of Pin-hinge Cable-beam Anchorage

针对销铰索梁锚固结构焊缝密集、局部应力集中明显的问题,以广州跨桂丹路刚架拱连续梁组合桥为研究对象,采用有限元理论分析与模型试验相结合的方法,对销铰索梁锚固结构的传力机理和疲劳性能进行研究。研究结果表明:(1)销铰锚固结构除部分区域存在应力集中外,整体应力水平不高,在1.5倍设计荷载下结构仍处于弹性阶段。(2)索力在结构中的传递是流畅、均匀的,但在焊缝内部的分配是不均匀的,其中耳板-桥面板、耳板-横隔板和耳板-桥面加劲板3处焊缝传递了80%以上的索力,焊缝端部存在一定应力集中,为疲劳设计关键部位。(3)在疲劳荷载下260万次循环加载后,疲劳试验模型的各关键细节均未发现裂纹,该结构疲劳性能满足要求。

The Pin-hinge cable-beam anchorage is critical to arch bridge given the stress concentrations and dense weld within it. With reference to the Guidan rigid frame arch bridge in Guangzhou, a case study on the load transfer mechanism and fatigue performance is carried out by using FEA and model test. The results indicate that(1) The stress level of anchorage zone is relatively low and the structure remains in elastic state under 1.5 times of the design load.(2) The transmission of cable force in the cable-beam anchorage zone is smooth and uniform, but its distribution in the weld is uneven. Three main welding lines in the ear plate and box girder transfer more than 80% of the total cable force. Certain stress concentration exists in the weld ends, which are critical areas of fatigue design.(3) No fatigue crack is found after 2.6 million load cycles, indicating that the structure’s fatigue performance meets the design requirement.