某连续刚构桥增设中墩加固方案研究  

Research on Adding Extra Intermediate Pier to Strengthen a Continuous Rigid-Frame Bridge

作　　者：黄炜 余健 李晓猛 HUANG Wei;YU Jian;LI Xiaomeng(Yunnan Provincial Highway Science and Technology Research Institute,Kunming 650051,China)

机构地区：[1]云南省公路科学技术研究院,云南昆明650051

出　　处：《世界桥梁》2023年第6期113-119,共7页World Bridges

基　　金：云南省交通运输厅科技计划项目(云交科教编[2020]18号)。

摘　　要：某连续刚构桥为(64+115+64)m变截面预应力混凝土箱梁桥,常规检测发现该桥存在主跨跨中下挠、混凝土开裂与预应力损失等病害。采用设置体外预应力钢束、封闭裂缝、粘贴碳纤维布和钢板等措施加固后,检测发现跨中仍持续下挠,需再次加固,因此提出在主跨跨中增设中墩的加固方案。中墩采用钢管混凝土格构式墩,墩身由4根钢管(管内填充C50混凝土)、“N”字形横向联结系、斜撑与斜联组成,钢材均为Q345qDNH钢;在主梁腹板外侧设置体外预应力,在主跨跨中新增中横梁并设置腹板加厚层。为研究该方案加固效果的有效性,采用有限元法对比分析增设中墩加固前、后结构的承载力,运用反应谱、动态时程与耐震时程法分析增设中墩加固前、后结构的抗震性能,基于等效试验荷载法评估增设中墩加固后结构的承载力与刚度。结果表明:增设中墩加固后结构承载力、刚度和抗震性能均有效提升,加固后实际工作状况较好。The bridge needing strengthening was a continuous rigid-frame bridge with three spans of 64,115 and 64 m.The superstructure consists of prestressed concrete box girders of variable cross-section.The regular inspections revealed that the bridge had suffered multiple deteriorations,including main-span midspan deflection,concrete cracking and prestress loss.Subsequently,the bridge was strengthened by adding external prestressing tendons,sealing cracks,bonding carbon fiber strips and steel plates.However,the strengthening did not resolve the midspan deflection issue of the bridge,and further strengthening was still needed.A recommended solution was to add an extra intermediate pier at the midspan of central span.The new intermediate pier has a latticed shaft consisting of four steel tubes filled with C50 concrete,N-shaped lateral bracings,diagonals,and inclined struts,and steel components are made of Q345qDNH steel.External prestressing tendons were added to the outer surface of the concrete box girder webs,new cross beams were installed at the midspan of central span,and the webs were thickened.To examine the strengthening effectiveness,the load bearing behaviors of the bridge were numerically simulated before and after installing the new intermediate pier,and the seismic performance of the bridge before and after the strengthening was analyzed by the response spectrum method,dynamic time history method,and seismic time history method.Based on the equivalent load test,the load bearing capacity and stiffness of the bridge after the strengthening by adding extra intermediate pier were evaluated.It is shown that the load bearing capacity,stiffness and seismic performance of the bridge after strengthening have been improved,and the serving condition of the bridge after strengthening is sound.

关 键 词：连续刚构桥 跨中下挠 增设中墩 钢管混凝土格构式墩 桥梁加固 

分 类 号：U448.23[建筑科学—桥梁与隧道工程] U445.72[交通运输工程—道路与铁道工程]