摘要
某长江大桥引桥为七跨一联和八跨一联30 m跨径连续箱梁桥,车辆超载和箱梁预应力损失等导致引桥箱梁跨中出现U形及L形裂缝等病害。考虑引桥联长较长、箱梁内净高较小及历次加固构件干扰等因素,对长索和短索体外预应力加固方案进行比选,确定采用七跨一联和八跨一联长索体外预应力方案加固。加固范围共计8联,每联布置6束体外预应力(含2束备用),体外预应力束采用19s15.2 mm环氧无粘结钢绞线,利用单根预紧千斤顶张拉,在箱梁内部设置厚200 cm钢筋混凝土锚固块,利用既有钢支撑和横隔板设置转向块。计算结果表明:张拉两对束时,七跨一联桥箱梁底板增加了1.3~3.2 MPa的压应力储备,该加固方案可行。该桥采用该方案加固后,达到了预期加固目标。
The approach bridge of a Changjiang River Bridge is a continuous box girder bridge with units of seven spans of 30 m and units of eight spans of 30 m.Vehicle overloads and prestress loss of box girder cause deterioration of box girders of approach bridge,including the U-and L-shaped cracks in the midspan.Given that the continuous units of the approach bridge were relatively long,the net inner depth of the box girder was relatively small,and the components added during the historical retrofits might disrupt the subsequent strengthening,two strengthening solutions were compared,including the one using long external prestressing tendons and the one using short external prestressing tendons,and the former was finally selected.The strengthening scope covers 8 continuous units,with the units of seven spans and the units of eight spans strengthened as individual entireties.In each of the selected continuous units,six prestressing tendons(2 back-ups)are added,and an individual prestressing tendon consists of 1915.2 mm epoxy-coated unbonded steel strands that are tensioned by single-strand jacks.The 200 cm-thick reinforced concrete anchorages are installed inside the box girders,and the existing steel supports and diaphragms are tapped for the installation of deviation blocks.The calculations demonstrate that when 2 pairs of prestressing tendons are tensioned,the compressive stress reservation of the box soffit in units of seven spans increases 1.3 to 3.2 MPa,proving that the solution is feasible.The expected strengthening objectives of the approach bridge are realized.
作者
张榄
姚磊
杨祖涛
ZHANG Lan;YAO Lei;YANG Zu-tao(Hubei Provincial Communications Planning and Design Institute Co. ,Ltd. ,Wuhan 430051,China;State Key Laboratory for Health and Safety of Bridge Structures,Wuhan 430034,China;China Railway Bridge Science Research Institute,Ltd. ,Wuhan 430034,China)
出处
《世界桥梁》
北大核心
2022年第4期108-112,共5页
World Bridges
关键词
连续梁桥
箱形梁
裂缝
长索体外预应力方案
加固设计
continuous girder bridge
box girder
crack
strengthening solution of using long external prestressing tendon
strengthening design
作者简介
张榄(1987-),男,高级工程师,2010年毕业于三峡大学土木工程专业,工学学士,2013年毕业于武汉理工大学交通运输工程专业,工程硕士(E-mail:137191083@qq.com)。
