大跨径连续梁桥体外预应力损失的数值分析与实桥测试  

Numerical Analysis and Field Measurement of External Prestress Loss in Long-span Continuous Girder Bridges

作　　者：薛翔宇 XUE Xiangyu

机构地区：[1]福建省林业勘察设计院,福建福州350003

出　　处：《福建建设科技》2023年第6期101-104,共4页Fujian Construction Science & Technology

摘　　要：预应力损失是大跨径梁桥长期下挠的重要影响因素,传统的体内预应力束存在管道压浆密实度难保障和预应力损失难测试等问题,使得桥梁永存预应力难以量化、结构运营状态难辨识。体外预应力具有损失少、永存应力可测试、主动受力等优点,目前体外预应力用于连续梁桥的工程案例还很少。本研究基于某预应力混凝土连续箱梁桥体内与体外混合配束特点,通过数值有限元分析和现场实测研究了体外预应力的损失规律。数值有限元分析表明体外预应力在施工完成后预应力损失在10%以内,运营阶段随着收缩徐变稳定后最终预应力损失在20%以内。实桥测试显示体外预应力在张拉完成50天后基本趋于稳定且损失率在6%以下,小于理论计算结果。本研究表明体外预应力技术可以很好地应用于大跨径连续梁桥设计建造中,预应力损失量低于设计预期,桥梁具有很好的预压应力储备。Prestressing loss is an important influence factor for the long-term deflection of long-span girder bridges.The traditional internal prestressing has shortfalls in guaranteeing the compactness of prestressing pipe slurry and testing the prestressing loss in service,which makes it difficult to quantify the permanent prestressing and recognize the operation status of the bridges.In contrast,external prestressing shows the advantages of less prestressing loss,testable stress status,active stressing,etc.However,there are currently few engineering cases of external prestressing used in continuous girder bridges.This study investigates a prestressed concrete continuous girder bridge with a hybrid design of internal and external prestressing.Finite element analysis,as well as on-site field measurements,were conducted to analyze the loss pattern of external prestressing.Finite element analysis shows that the losses of external prestressing forces are less than 10%after the completion of the construction,and the final losses are less than 20%after stabilization with shrinkage and creep during the operation stage.On-site field measurements show that the losses of prestressing force tend to stabilize after 50 days of tensioning and the loss rates are less than 6%,which is smaller than the numerical results.Therefore,this study proves that the external prestressing technique can be well applied to the design of long-span continuous girder bridges,the prestress loss is lower than the design expectation,and the bridges would have good precompression stress reserve.

关 键 词：大跨径梁桥 长期下挠 体外预应力 预应力损失 数值模拟 实桥测试 

分 类 号：U448.215[建筑科学—桥梁与隧道工程]