悬臂现浇混凝土梁桥腹板沿波纹管裂缝成因分析  

Causes Analysis of Cracks in Webs of Cast-in-Situ Concrete Beam Bridge along Corrugated Ducts

作　　者：于孟生 郝天之 黄凯楠 骆俊晖 陈齐风 YU Meng-sheng;HAO Tian-zhi;HUANG Kai-nan;LUO Jun-hui;CHEN Qi-feng(Guangxi Transportation Science and Technology Group Co. , Ltd. , Nanning 530007, China;Guangxi Beitou Transportation Maintenance Technology Group Co. , Ltd. , Nanning 530004, China;Guangxi University of Science & Technology, Liuzhou 545026, China)

机构地区：[1]广西交科集团有限公司,广西南宁530007 [2]广西北投交通养护科技集团有限公司,广西南宁530004 [3]广西科技大学,广西柳州545026

出　　处：《世界桥梁》2021年第5期100-106,共7页World Bridges

基　　金：南宁市“邕江计划”资助项目(20180104);广西自然科学基金项目(2019JJA160103)。

摘　　要：某悬臂现浇预应力混凝土箱梁桥跨径布置为(91.2+2×160+91.2)m,主梁为单箱单室箱梁,成桥后检查发现箱梁腹板出现大量沿波纹管方向斜裂缝。为了解箱梁腹板斜裂缝成因,基于弹性力学平面理论推导出箱梁腹板在锚头局部压力作用下的横向主应力计算公式,分析箱梁腹板横向主拉应力;采用Abaqus软件建立主梁有限元模型,计算竖向预应力张拉顺序和预应力损失、下弯束曲率半径、腹板厚度、预应力束数量对腹板主拉应力的影响。结果表明:理论计算得到箱梁腹板横向主拉应力最大值为1.98 MPa,会导致腹板开裂;箱梁计算开裂位置与实际裂缝位置基本一致;竖向预应力张拉滞后、腹板下弯束预应力锚固端局部压力过大、腹板下弯束曲率半径过小、腹板厚度减小均会导致腹板垂直于波纹管方向的主拉应力增大,是导致腹板产生沿波纹管方向斜裂缝的主要原因。A concrete box girder has four spans of 91.2 m,2×160 m and 91.2 m and was constructed by cast-in-situ cantilever method.The superstructure consists of single-cell box girders.A large number of diagonal cracks were found in the webs of the box girder along the corrugated ducts.To analyze the causes of these diagonal cracks,the calculation formulas of transverse main stresses in the box girder webs induced by local compression from anchor heads were derived based on the elastic mechanics theory.A finite element model of the superstructure was established by Abaqus to calculate the influence of a series of factors on the principal tensile stress in the webs,including the tensioning sequence of vertical prestressing tendons,prestress loss,curvature radius of downward-draped tendons,web thickness and the amount of prestressing tendons.The results show that the maximum calculated transverse principal tensile stress is 1.98 MPa,which can cause web cracking.If the tensioning of vertical prestressing tendons is delayed,the local compressive forces in the anchoring end of downward-draped prestressing tendons in the webs are oversized,the curvature radius of the downward-draped prestressing tendons in the webs is undersized,and the web thickness is decreased,the principal tensile stress in the webs perpendicular to the corrugated ducts would increase,which are considered the main causes of the diagonal cracks in the webs along the corrugated ducts.

关 键 词：箱形梁 悬臂现浇 预应力 腹板 裂缝 裂缝成因 理论分析 有限元法 

分 类 号：U448.213[建筑科学—桥梁与隧道工程] U445.71[交通运输工程—道路与铁道工程]