摘要
为分析整体顶推提篮拱桥施工过程的力学性能,该文以宁波新典桥为背景,运用Midas有限元软件建立主桥空间模型,得到成桥吊杆力、支座反力与设计的偏差分别为1.84%、1.80%,系梁成桥阶段位移计算最大偏差值为22 mm,拱肋成桥阶段位移最大偏差值为-12 mm,表明有限元模型模拟方法正确、可靠。顶推过程中,杆系单元计算系梁最大剪应力为112 MPa,小于规范设计强度值160 MPa。参考规范按支座处支承加劲肋计算方法,系梁局部承压强度验算结果为114 MPa,小于《公路钢结构桥梁设计规范》(JTG D64—2015)的355 MPa要求,局部失稳结果为234 MPa,小于规范275 MPa的要求。通过分析局部模型,腹板按第四强度理论计算的等效应力为181.7 MPa,按第三强度理论计算的等效应力为204.4 MPa,结果均满足规范容许应力252 MPa的要求。由于腹板受力较大,富余量不足,采用支点强制位移值为2 cm,此时剪应力由112 MPa降至95 MPa,桥梁在整个顶推过程中未出现板件破坏与屈服现象,表明计算方法与结果能够指导实际施工。体系转换计算两种工况:①从中到边对称拆除;②从边到中对称拆除。分析结果表明两种方案结构受力影响不大,但从中到边拆除方案梁拱相对变形较小,对吊杆安装有利。
Taking the Xindian Bridge in Ningbo as the background,this paper analyzed the mechanical properties of the integral jacking basket arch bridge during construction.Midas finite element software was used to establish the spatial model of the main bridge,and the deviation of the suspender force and support reaction force of the completed bridge from the design was 1.84%and 1.8%,respectively.The maximum deviation of the displacement calculation of the tie beam at the bridge completion stage was 22 mm,and the maximum deviation of the displacement of the arch rib at the same stage was‒12 mm,which showed that the finite element model simulation method was correct and reliable.During the jacking process,the maximum shear stress of the tie beam calculated based on the truss unit was 112 MPa,which was less than the design strength value of 160 MPa in the specification.According to the calculation method of bearing stiffeners at the support in the specification,the checking result of the local bearing strength of the tie beam was 114 MPa,less than the 355 MPa required in the Specifications for Design of Highway Steel Bridge(JTG D64‒2015).The local instability result was 234 MPa,less than 275 MPa required in the specification.According to the analysis of the local model,the equivalent stress of the web calculated by the fourth strength theory was 181.7 MPa,and that calculated by the third strength theory was 204.4 MPa.The results met the requirements of the allowable stress of 252 MPa in the specification.Due to the large force on the web and the insufficient surplus,the shear stress was reduced from 112 MPa to 95 MPa when the forced displacement value of the fulcrum was 2 cm,and no failure and yield of the plate appeared in the whole process of the bridge jacking,which showed that the calculation method and results could guide the actual construction.Two working conditions were calculated for system conversion: ① Symmetrical removal from the center to the edge;② symmetrical removal from the edge to the center. The analysis results show that the two schemes have little influence on the structural force, but the scheme featuring symmetrical removal from the center to the edge has relatively little deformation of the beam arch, which is beneficial to the installation of the suspender.
作者
陈涛
邱景奎
王吉
CHEN Tao;QIU Jingkui;WANG Ji(State Key Laboratory of Bridge Intelligent and Green Construction,Wuhan,Hubei 430034,China;China Railway Bridge Science Research Institute Ltd.,Wuhan,Hubei 430034,China)
出处
《中外公路》
2025年第3期145-152,共8页
Journal of China & Foreign Highway
基金
湖北省自然科学基金资助项目(编号:2022CFB558)。
关键词
提篮拱桥
整体顶推
有限元模型
局部失稳
等效应力
强制位移
体系转换
basket arch bridge
integral jacking
finite element model
local instability
equivalent stress
forced displacement
system conversion
