摘要
货车在桥梁伸缩缝处的跳车和对梁端的撞击可能显著放大正交异性钢桥面板(OSD)构造细节上的应力,降低梁端OSD的疲劳性能,而现有规范可能明显低估了梁端疲劳荷载放大系数。基于随机车流下某大跨斜拉桥梁端和桥跨处纵肋-面板(RD)构造细节的应力监测,分析了应力响应和纵桥向分布特征,评价了RD构造细节的疲劳性能,并基于疲劳等效研究了梁端RD构造细节的疲劳荷载放大系数和纵桥向的分布规律。研究发现,梁端货车动力效应同时增大了RD构造细节应力幅和疲劳荷载循环次数,RD构造细节的应力水平明显高于桥跨处,特别是其面板侧,该动力效应随离开伸缩缝的距离增大而降低。基于单货车或随机车流的等效应力幅均无法给出疲劳荷载放大系数的合理估计。参考中国规范,从损伤度计算应力幅的角度拟合了梁端RD构造细节的疲劳荷载放大系数表达式,放大系数最大值明显高于中国和美国规范,影响范围也从中国规范的梁端6 m增大到10 m。在桥梁设计中,通过规范疲劳车模型和采用本文建议的疲劳荷载放大系数表达式,可望提高大跨度桥梁梁端OSD的抗疲劳性能。
The impact and bumping of trucks on expansion joints may significantly increase the stress level in the details of the orthotropic steel deck(OSD),and hence reduce the fatigue performance of OSD close to the expansion joints.The existing codes may underestimate the amplification factor of fatigue load at the bridge girder end.Based on the simultaneous stress measurements of rib-to-deck detail(RD)close to or far away from the expansion joints in a long-span cable-stayed bridge under random traffic flow,the stress responses and their longitudinal distributions are analyzed,followed by the fatigue life evaluation of RD details.Based on the law of fatigue life equivalence,the fatigue load amplification factor and its longitudinal distribution at RD details are investigated.It is found that the truck impact at the bridge girder end increases both the stress ranges and the fatigue loading cycle at the RD detail.The stress level at the RD detail close to the expansion joint is higher than that of the bridge span,especially for the deck plate side of the RD detail.The amplifica-tion factor decreases with the increase in the distance from the expansion joint.However,the stress ranges un-der the passage of a single truck or random traffic flow cannot provide a reasonable value of fatigue load ampli-fication factor.According to the Chinese code,the expression of the fatigue load amplification factor of the RD at bridge girder end is fitted based on the concept of fatigue damage degree,and the maximum value ob-tained by the expression is significantly higher than those recommended by the American or Chinese codes,and the influence range is also increased from 6 m to 10 m.Based on the fatigue vehicle model in Chinese codes and the suggested expression of fatigue amplification factor at the bridge girder end,it is expected to im-prove the fatigue performance of OSD in long-span bridges.
作者
祝志文
钟国琛
丁望星
ZHU Zhiwen;ZHONG Guochen;DING Wangxin(Department of Civil Engineering,Shantou University,Shantou 515063,China;Hubei Provincial Communications and Design Institute Co.,Ltd.,Wuhan 430051,China)
出处
《东南大学学报(自然科学版)》
北大核心
2025年第6期1707-1716,共10页
Journal of Southeast University:Natural Science Edition
基金
国家自然科学基金资助项目(52278509)。
关键词
正交异性钢桥面板
疲劳
主梁梁端
疲劳荷载放大系数
应力监测
orthotropic steel deck
fatigue
main girder end
fatigue load amplification factor
stress monitor-ing
