摘要
宜都枝城长江大桥为公铁两用钢桁架连续梁桥,服役多年后,两主桁外侧公路托架角钢出现开裂病害。为探究病害成因,并选取合适的处理措施,采用Abaqus软件建立多层次精细化有限元模型,分析加固前、后多工况下角钢开裂部位的力学响应与托架易损点的疲劳特性。结果表明:托架竖直角钢与上弦角钢翼缘分离,局部区域发生明显的应力集中,最大等效应力为139.2 MPa;公路桥纵梁不连续,使得桥梁受载时托架发生扭转;桥面的超载现象严重,托架纵向拉应力峰值增大率达153.4%,是导致托架局部角钢开裂的重要因素。采用增大垫板尺寸、恢复竖直角钢上端的顶紧状态、在角钢裂缝两侧设置T形钢板等措施对病害处进行了处理,加固后上弦角钢最大等效应力降低62.7%,处理效果良好。
The Zhicheng Changjiang River Bridge in Yidu is a continuous steel truss girder bridge accommodating both highway and railway traffic.After years of operation,cracks have occurred in the angle section of brackets flanked the two main trusses at the upper deck.To investigate the causes of deteriorations and figure out proper treatment,a refined multiscale finite element model was established by Abaqus.In different load cases,the mechanical responses of the cracked locations of angle section and the fatigue characteristics of the damage-prone points in the brackets before and after strengthening were examined.The results indicate that the vertical angle section of the bracket was disengaged from the flanges of upper chord angle section,triggering obvious local stress concentration,with the maximum equivalent stress reaching 139.2 MPa.Because the longitudinal beams supporting the highway deck are not continuous,the brackets are susceptible to twist when loaded.The highway deck is severely overloaded,making the peak longitudinal tensile stress in the bracket increased by 153.4%.These are the main causes of cracks in local angle section of the brackets.The strengthening work incorporated enlarging the area of backing plates,restoring the tight connection between the head of vertical angle section and the upper chord angle section,adding T-shaped steel plates on the two sides of the cracks in angle section.After strengthening,the maximum equivalent stress in the upper chord angle section is reduced by 62.7%,proving that the strengthening effect is good.
作者
付军
王哲世
余昆
余恒
FU Jun;WANG Zhe-shi;YU Kun;YU Heng(School of Transportation, Wuhan University of Technology, Wuhan 430063, China;The Seventh Engineering Co. , Ltd. , China Railway Major Bridge Engineering Group, Wuhan 430056, China;China Railway Siyuan Survey & Design Group Co. , Ltd. , Wuhan 430063, China)
出处
《桥梁建设》
EI
CSCD
北大核心
2021年第3期32-38,共7页
Bridge Construction
基金
国家自然科学基金项目(51708433)。
关键词
公路铁路两用桥
钢桁架连续梁桥
托架角钢
开裂病害
病害处理
精细化有限元分析
rail-cum-road bridge
continuous steel truss girder bridge
bracket angle section
cracking deterioration
deterioration treatment
refined finite element analysis
