Long-term deformation assessment of a long-span concrete bridge built by the cantilever erection method

Abstract The balanced cast-in-place cantilever erection method has become a popular construction bridge technique. The main advantages include an industrialized erection technique that prevents the use of intermediate supports and rapid construction. However, the long-term response of this bridge typology is not well understood as long-term deflections due to time-dependent phenomena (such as creep and shrinkage) are significantly simplified in bridge design codes. Existing prediction models commonly used in design tend to underestimate long-term deflections, and as a result, field measurements conducted in newly constructed bridges still report excessive long-term deflections. This paper shows the long-term deflection analysis of a long-span concrete bridge located in Colombia and opened to traffic in 2014. This study is conducted using field data collected within a one-year time interval and modelling results. Further comparisons using field data collected from bridges with similar structural configurations, but opened to traffic in the 90s and 2000s, show that the bridge's current situation is categorized as a major concern.摘要 平衡悬臂现浇施工法已成为主流的桥梁建造技术。其核心优势在于采用工业化施工工艺，无需搭设中间支架，且施工效率极高。然而，由于桥梁设计规范中对徐变、收缩等时变效应引发的长期挠度进行了大幅简化，这类桥梁结构的长期力学响应尚未得到充分认知。当前设计领域常用的挠度预测模型往往低估长期挠度值，因此新建桥梁的现场监测数据仍频繁出现长期挠度超标的情况。本研究针对哥伦比亚境内一座2014年通车的大跨度混凝土桥梁开展了长期挠度分析，分析基于为期一年的现场监测数据与数值模拟结果完成。进一步对比上世纪90年代及2000年代通车的同结构形式桥梁的现场监测数据后发现，该桥梁当前的状态已被列为重大安全关切事项。