基于反拉法的预制混凝土小箱梁锚下有效预应力损失影响因素研究

Study on the Influence Factors of Effective Prestress Loss Under Anchor of Small Precast Concrete Box Girder by Reverse Tension Method

预制梁锚下有效预应力是反映结构工作状态的重要指标,准确识别梁体锚下有效预应力的大小可提高桥梁结构的安全性和使用性,但由于施工工艺、材料性能、环境等多因素的影响,导致预制梁锚下有效预应力在注浆之前就产生了一定程度的损失。为探索锚下有效预应力损失超量效应,以广东省肇庆市新桥大桥新建预制混凝土小箱梁为例,基于反拉法分析了梁体起拱度、分批张拉和时间效应对预制混凝土小箱梁锚下有效预应力的影响规律,针对各影响因素提出了相应的改善措施,尽可能保证了张拉后预制混凝土小箱梁锚下预应力的有效性,为施工张拉后锚下有效预应力损失的控制措施提供了指导与借鉴。

Effective prestress under anchor is an important index reflecting the working condition of the structure.Whether the size of the effective prestress under anchor of the girder can be accurately identified or not is related to the safety and usability of the bridge structure.Due to the influence of various factors of construction process,material properties,and the environment,a certain degree of the effective prestress loss is produced under anchor before grouting.In order to explore the excess effect of the loss,the small new precast concrete box girder of Xinqiao Bridge in Zhaoqing City,Guangdong Province is taken as an example.The effective prestress was analyzed by the reverse tensioning method.The impact of the girder archedness,batch tensioning and time effect were summarized.The corresponding improvement measures were proposed for each influencing factor,which ensured the effectiveness of the effective prestress under anchor as much as possible after the tensioning.This research provides guidance and reference for controlling measures of the effective prestress loss under anchor after the tensioning of the construction.