大宽跨比独塔斜拉桥超宽正交异性钢箱结合梁受力分析  

Stress Analysis of Ultra-Wide Orthotropic Steel Box Girder with Large Width-Span Ratio and Single Inclined Pylon

作　　者：尚致朝 陈立 陈钒 李廷钰 田勇 Zhichao Shang;Li Chen;Fan Chen;Tingyu Li;Yong Tian(Power China Road Bridge Group Co.,Ltd.,Beijing 100160,China)

机构地区：[1]中电建路桥集团有限公司,北京100160

出　　处：《钢结构（中英文）》2021年第9期19-24,共6页Steel Construction（Chinese & English）

摘　　要：独塔斜拉桥的几何非对称特性导致其应力和变形不同于一般同类桥,大宽跨比正交异性钢箱梁的薄壁结构使得其受力及变形更为复杂,用常规方法难以精确给出变形和应力值。贾鲁河大桥即是这样一个例子,而且复杂性进一步增加。120 m的主跨分成三部分:从主塔开始的100m是正交异性钢箱梁,紧接的8m过渡段与12m的混凝土梁段衔接,后者系从对岸墩台伸出的悬臂段。由于钢箱梁宽度达54.8m,且未直接支撑在对岸桥墩上,而是通过一个8m长、54.8m宽的过渡梁段间接与混凝土伸臂梁连接,属于小范围内刚度不同的三种材料的连接,由此形成的两道连接缝不但削弱了结构的整体性,而且使对准和控制环节多,进一步增加了施工控制的难度。研究表明:钢箱梁横向变形基本一致,最大横向变形相对差值为-2.8 mm,施工时可不设横向预拱度;自重作用引起的钢箱梁最大Mises应力为93.7 MPa,二期恒载和活载作用下的最大Mises应力约为自重引起的1/4,表明钢箱梁应力具有较大的安全富余度;当U肋高度在260~320 mm范围变化时,桥面系位移变化幅度不超过5%,桥面板最大应力变化幅度不超过8%,此范围内U肋高度变化对桥面系位移和应力的影响均较小,内在原因是U肋的高低变化与横梁能提供的刚度是互补的,正好说明该正交异性钢箱梁具有显著的板的特征,设计上宜采用此范围内的U肋高度。Geometrical asymmetry in cable-stayed bridges with single pylon leads to differences in stresses and deformation in comparison to conventional ones.Thin-walled orthotropic steel girder with big width/span ratio has more complicated loading and deformation performance,which cannot be calculated accurately using conventional approaches.Jialuhe bridge is such an example with even more complicated properties.The 120 m long main span consists of three segments:The first 100 m from the pylon is orthotropic steel girder,followed by 8 m transition segment,and the last 12 m reinforced concrete plate is a cantilever from the abutment on the opposite bank.The width of the steel girder is 54.8 m,not supported on the abutment directly,but connected to the cantilever through a transitional segment with 8×54.8 m side length instead.So there are three materials of different stiffness connected in a small space,leading to two seaming sections,which not only reduces the monolith of the structure,but also increases difficulties in construction controlling.The investigate shows:The transverse deformation of the steel girder is identical,with a maximal relative difference of-2.8 mm,so that no transverse camber is needed in construction phase.The maximal Mises stress due to gravity is 93.7 MPa,and that due to secondary deadload is about 1/4 of this value.This reveals a big safety reserve of the steel girder.When the height of the U-stiffeners varies between 260~320 mm,the variation of displacements of the bridge deck lies within 5%,variation of maximal stresses of the bridge deck within 8%.In this range the variation of the height of the U-stiffeners has less impact on displacement and stress of the deck.The internal cause is that the height of U-stiffener and the stiffness delivered by the transverse girder are supplementary each other,just demonstrating the salient plate property of this orthotropic girder.Height of U-stiffeners in this range should be chosen when designing.

关 键 词：大宽跨比 正交异性钢箱梁 有限混合单元 U肋设计高度 

分 类 号：U448.27[建筑科学—桥梁与隧道工程]