基于现场监测的超宽弯斜混凝土箱梁力学特性分析  

Analysis of Mechanical Property of Very-Wide Curved Concrete Box Girder Based on Field Monitoring

作　　者：秦煜 肖金辉[3] 李青良 徐长春 陈斌 QIN Yu;XIAO Jin-hui;LI Qing-liang;XU Chang-chun;CHEN Bin(China Railway Eryuan Engineering Group Co.,Ltd.,Chongqing 400023,China;School of Civil Engineering,Chongqing Jiaotong University,Chongqing 400074,China;Guangzhou Testing Center of Construction Quality and Safety Co.,Ltd.,Guangzhou 510440,China)

机构地区：[1]中铁二院重庆勘察设计研究院有限责任公司,重庆400023 [2]重庆交通大学土木工程学院,重庆400074 [3]广州建设工程质量安全检测中心有限公司,广东广州510440

出　　处：《桥梁建设》2020年第3期64-69,共6页Bridge Construction

基　　金：国家自然科学基金项目(51978114);重庆市自然科学基金项目(cstc2019jcyj-msxmX0796);中铁二院科学技术研究计划项目(14126146,KYY2019061)。

摘　　要：为掌握宽弯斜混凝土箱梁的荷载效应分布特征,以某5×20 m的预应力混凝土连续梁桥(箱梁宽54 m,曲线半径小,斜交)为背景,开展从混凝土箱梁浇筑至运营前共1年的监测,采集并分析箱梁的应变和挠度;基于梁格法,建立箱梁有限元模型,分析箱梁纵、横向应力及竖向挠度。结果表明:监测期内,箱梁的应变和挠度变化显著;钢束张拉后箱梁跨中底板横向压应变小幅减小;满堂支架拆除后箱梁应变调整1~2 d;箱梁纵向应变长期趋于平稳;预应力引起跨中上拱,曲线内侧至外侧上拱幅度逐渐减小;跨中断面横向应变比例集中在0~1且极值相差很小;弯桥与直桥跨中断面纵向应力差与曲线半径正相关;弯扭耦合作用下箱梁外侧箱室挠度陡增;宽跨比较大的曲线箱梁可按梁格法计算,进行纵向配束,并加强横向设计。To study the characteristics of load effect distribution of wide curved concrete box girder,a prestressed concrete continuous girder bridge with spans of 5×20 m was taken as the study background.The concrete box girder is 54 wide,with a mall radius and a skew angle.A one-year long monitoring from the casting of the concrete box girder to the state of the bridge before operation was conducted,upon which the data of stain and deflection of the box girder were collected and analyzed.Based on the grillage method,the finite element model of the box girder was built,to analyze the longitudinal and transverse stresses as well as the vertical deflection of the box girder.The results show that during the monitoring period,the variation of strain and deflection of the box girder was obvious.After the tensioning of prestressing tendons,the transverse tensile strain in the midspan soffit of the box girder slightly decreased.After the demolition of the full-space scaffolds,the box girder was left alone for one or two days for strain adjustment.The longitudinal strain of the box girder tended to be stable in the long run.Prestress caused the upwarping of the box girder at midspan,whereas the upwarping gradually flattened from the inner side of the curve to the outer side.The cross-section transverse strain ratios were within the range of 0-1,with small difference between limit values.For both the curved and straight bridges,the differences of longitudinal stresses in the midspan cross-section were in proportional to the curvature radius.Under the bending-torsion coupling effect,the deflection of outer cell of the box girder spiked.To the curved box girder with big width-to-span length ratio,the grillage met hod can be used for calculation to figure out the layout of prestressing tendons and make proper transverse design.

关 键 词：曲线桥 斜交桥 宽箱梁 预应力混凝土结构 力学特性 现场监测 应变 有限元法 

分 类 号：U448.213[建筑科学—桥梁与隧道工程] U446.2[交通运输工程—道路与铁道工程]