预应力混凝土箱梁桥悬臂施工阶段剪力滞效应  

Shear lag effect in cantilever construction of prestressed concrete box girder bridge

作　　者：任翔[1] 张伊飞 齐海鹏[1] REN Xiang;ZHANG Yifei;QI Haipeng(School of Architecture and Civil Engineering,Xi′an University of Science and Technology,Xi'an 710054,China)

机构地区：[1]西安科技大学建筑与土木工程学院,陕西西安710054

出　　处：《混凝土》2022年第3期145-149,共5页Concrete

基　　金：国家自然科学基金(51408484);陕西省重点研发计划(2018SF-359)。

摘　　要：在预应力混凝土连续箱梁桥悬臂施工过程中,剪力滞效应对主梁结构有极大的影响。以某单箱单室和某单箱双室截面预应力混凝土连续箱梁桥为工程背景,建立FEA实体模型对悬臂施工过程进行模拟,对比分析单箱单室和单箱双室截面箱梁在挂篮、混凝土浇筑、预应力张拉工况下的剪力滞效应,并对最大悬臂阶段悬臂根部有效分布宽度与规范进行对比分析。结果表明:实测数据与有限元计算结果基本一致,验证了有限元分析的有效性;预应力张拉能够有效降低主梁的剪力滞效应;随悬臂长度的增加,剪力滞效应在悬臂端部变大且变化幅度增大;中腹板的设置能有效降低单箱双室箱梁的剪力滞效应;设计施工时按照规范计算截面有效宽度能够有效保证结构的安全,但单箱双室截面箱梁在挂篮工况下有限元计算值略大于规范计算值,在施工时应着重注意。In the cantilever construction of prestressed concrete continuous box girder bridge,the shear lag effect has a great impact on the main girder structure.With a single-box single-cell bridge and a single-box double-cell prestressed concrete continuous box girder bridge as the engineering background,the FEA solid finite element model was established to simulate the cantilever construction process accurately.The analysis of the single-box single-cell and single-box double-cell shear lag effect in the hanging basket,concrete pouring and the shear lag effect of prestressed tensioning condition have be done.Meanwhile,the effective distribution width at the cantilever root in the maximum cantilever stage is compared with the standard.The results show that the measured data are basically consistent with the calculated results of finite element,which verifies the effectiveness of the finite element analysis.The shear lag effect of the girder can reduced effectively under the prestressed tensioning condition.With the development of cantilever construction,the shear lag effect at the end of cantilever is obvious and the variation amplitude of the shear lag coefficient increases.The middle web can reduce the shear lag effect of the single-box double-cell girder effectively.The effective distribution width in the design and construction calculated according to the code can ensure the safety of the structure effectively.However,the finite element calculation value of the box girder with single-box double-cell section is slightly larger than the standard calculation value under the condition of hanging basket,which should be paid more attention to during the construction.

关 键 词：箱型结构 悬臂施工 剪力滞效应 有限元模拟 有效分布宽度 

分 类 号：TU528.7[建筑科学—建筑技术科学]