空间缆索悬索桥是一种主缆、吊索等缆索系统向横桥向内侧倾斜或是外侧倾斜的悬索桥体系,其中吊索是重要的传力构件,但是其抗力会随着桥梁服役期的增加而下降,这会导致构件失效概率的增加和结构安全性问题。以主跨1 666 m的整体式钢箱梁悬索桥为工程背景,采用不同的主缆内倾角度,试设计了7个空间缆索体系悬索桥方案。通过建立吊索抗力时变概率模型、恒载内力时变概率模型以及风载内力时变概率模型,分析比较了在恒载和极值静风荷载作用下,空间缆索悬索桥吊索可靠度指标随服役期的变化规律。分析结果表明：受均匀腐蚀与点蚀影响的吊索抗力在钢丝体开始腐蚀后的10年内,吊索的抗力不拒绝伽马分布;在第10年到第30年间,吊索抗力不拒绝韦布尔分布。吊索风载内力在服役期40年内不拒绝对数正态分布。悬索桥吊索的时变可靠度与空间缆索体系的内倾角度不相关,且同一悬索桥不同位置处的吊索耐久可靠度变化形式一致。
Abstract
Spatial-cable suspension bridges consist of main cables and hangers inclined either to the inner or outer side in the transverse direction of the bridge. The hangers play a vital role in load transmission; however, their resistance decreases with the bridge's service life, leading to an increase in component failure probability and structural safety concerns. In this study, a steel box girder suspension bridge with a main span of 1666m serves as the engineering background, and seven designs of the suspension bridge with different inclination angles of main cables are proposed. By establishing the time-varying probability models of the resistance, internal forces under dead load and internal force under wind load only, the variation of the reliability index of hangers with the service period under the condition of the dead load and the extreme static wind load is analyzed and compared. The study shows that within ten years of the steel wire starting to corrode, the distribution of resistance of hangers affected by uniform and pitting corrosion does not reject the gamma distribution. From the 10th to 30th year, the distribution of resistance of hangers does not reject the Weibull distribution. The distribution of internal force of hangers under wind load only does not reject the logarithmic normal distribution within 40 years of service. The time-varying reliability index of all the hangers of the suspension bridge is uncorrelated with the inclination angle of the cables, and the variation of the time-varying reliability index of the hangers at different positions of the same suspension bridge is consistent.
关键词
空间缆索悬索桥 /
内倾角 /
吊索耐久性 /
极值风荷载 /
概率模型 /
可靠度分析
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Key words
suspension bridge with spatial cables /
inclination angle /
durability of hangers /
extreme wind load /
probability model /
reliability analysis
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脚注
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基金
国家自然科学基金资助项目（52178503）
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