石首长江公路大桥短线法预制PC主梁设计研究  

Study of PC Main Girder Fabricated by Short-Line Match Method for Shishou Changjiang River Highway Bridge

作　　者：张家元 詹建辉 丁望星 ZHANG Jia-yuan;ZHAN Jian-hui;DING Wang-xing(Hubei Provincial Communications Planning and Design Institute Co.,Ltd.,Wuhan 430051,China)

机构地区：[1]湖北省交通规划设计院股份有限公司,湖北武汉430051

出　　处：《世界桥梁》2019年第1期16-21,共6页World Bridges

摘　　要：石首长江公路大桥主桥为主跨820m的双塔不对称混合梁斜拉桥。中跨和南边跨采用钢箱梁,北边跨采用预应力混凝土主梁。结合场地水文和地质特点、宽幅大截面箱梁抗裂和质量要求,PC主梁采用"地面预制+支架存梁"的短线法预制拼装施工方案。主梁纵向体内预应力采用大直径优质合金高强钢棒预应力体系,配套采用体内+体外束预应力设计。通过采用地面预制的施工方案、构造优化和横向预应力多次分批张拉、混凝土的配合比及温控养护措施,在宽幅、大截面箱梁的匹配预制精度控制、裂缝控制上取得了预期效果。北边跨预制PC梁胶拼成跨,不设湿接缝,通过无应力长度参数和梁段间竖向转角参数的精度控制保证成桥线形。北边跨PC主梁预制精度、工程质量和拼装线形达到了设计预期。The main bridge of Shishou Changjiang River Highway Bridge is a two-pylon cable-stayed bridge with a main span of 820 m.The main girder adopts the asymmetric hybrid girder,in which the central and the south side spans use steel box girder,and the north side spans use prestressed concrete girder.In accordance with the hydrological and geological condition at the bridge site and the anti-cracking and quality demands of the wide steel box girder with large cross section,the PC main girder is constructed by the short-line prefabrication and assembly scheme,by which the girder is prefabricated on the ground,and then,stored on the scaffoldings.The internal longitudinal prestressing of the main girder adopts the large-diameter high-quality high-strength alloy steel bars,together with the design of the internal and external prestressing.The control of match prefabrication accuracy and cracks of the wide steel box girder with large cross section achieved the anticipated effect,due to the adoption of a series of measures,like taking the construction scheme of prefabrication on the ground,optimizing the structural composition,tensioning the transverse prestressing in groups and by multiple times,rationalizing the mix proportion of concrete,temperature control and concrete curing.The PC girders in the north side spans were glued to form spans,with no wet joints.The parameters of zero-stress length and the accuracy of the vertical rotation angles of the girder sections were controlled to ensure the alignment of the completed bridge.The prefabrication accuracy,engineering quality and assembling geometry of the PC main girder in north side spans reached the design expectation.

关 键 词：斜拉桥 混合梁 双边箱主梁 短线法 预应力体系 裂缝控制 预制精度 设计 

分 类 号：U448.27[建筑科学—桥梁与隧道工程] U441[交通运输工程—道路与铁道工程]