池州长江公路大桥北边跨钢-混结合段施工关键技术

池州长江公路大桥主桥为主跨828 m的双塔双索面非对称混合梁斜拉桥,除北边跨主梁采用混凝土箱梁结构外,其余主梁均采用钢箱梁结构。钢-混结合段长11.2 m、全宽39.0 m,布置在Z3号墩向跨中方向3 m的位置处;采用承压传力结构形式,通过剪力钉与现浇混凝土连接,并设置纵向预应力钢束。根据现场施工条件,先利用800 t浮吊将结合段钢梁吊装至钢管滑移支架,并利用滑移系统将其滑移至起吊位置;然后利用2台300 t变幅式桥面吊机、采用双悬臂法对称吊装钢梁,钢梁吊装到位后进行纵向、轴线及标高调整;钢梁精确定位后进行临时锚接及钢梁环口精确匹配,利用支撑锁定支架进行钢梁临时锁定;钢梁锁定后绑扎钢-混结合段钢筋、安装预应力管道,浇筑箱梁混凝土,完成钢-混结合段施工。

Key Construction Techniques for Steel-Concrete Joint Section in North Side Span of Chizhou Changjiang River Highway Bridge

The main bridge of Chizhou Changjiang River Highway Bridge is a two-pylon asymmetrical hybrid girder cable-stayed bridge with a main span of 828 m.The stay cables are arranged in double cable planes.The main girder of the north side span consists of concrete box girders,and the remaining part of the main girder of the bridge is comprised of steel box girders.The steel-concrete joint section is located at the place 3 m to the pier Z3 in the midspan direction,which is 11.2 m long and measures 39.0 m in full width.The steel girders are connected with the cast-in-situ concrete via shear studs to form a load bearing and force transmission structure,where longitudinal prestressing tendons are also installed.To suit the construction conditions at the bridge site,the steel boxes in the joint section was first hoisted by the 800 t-capacity floating cranes to the sliding scaffolds formed of steel tubes,and moved to the final hoisting locations by the sliding system.Then,two 300 t-capacity luffing deck cranes were deployed to install the steel girders symmetrically by the two-cantilever method.When the steel girders were lowered into position,the longitudinal alignment and axial lines as well as the elevations were adjusted.After being precisely positioned,the steel girders were temporarily anchored,and the openings of adjacent steel girders were precisely matched,and the supporting framed locks were employed to temporarily lock the steel girders.When the steel girders were locked,the reinforcement in the steel-concrete joint section were bound,the conduits for the prestressing tendons were installed,and the concrete of the box girder was cast to complete the construction of the steel-concrete joint section.