武汉鹦鹉洲长江大桥主桥加劲梁架设施工技术

Construction Techniques for Erection of Stiffening Girder of Main Bridge of Yingwuzhou Changjiang River Bridge in Wuhan

武汉鹦鹉洲长江大桥主桥为(200+2×850+200)m三塔四跨悬索桥,上部结构加劲梁为钢-混凝土结合梁。加劲梁采用500t液压提升式缆载吊机分节段起吊安装,最大节段重约450t;边跨节段起吊前,将桥面板与钢梁结合成整体;中跨节段起吊前,将桥面板与钢梁临时固定,然后一起起吊安装,直至全桥合龙后再浇筑桥面湿接缝。全桥共投入4台缆载吊机,先在2个中跨各布置2台,吊装完成每个中跨约3/4的梁段,然后分别倒用1台至边跨,再共同完成剩余梁段的吊装。边塔下横梁顶无吊索梁段采用新型对拉式墩旁托架支撑。对拼装场地受限的特殊梁段,利用永久吊索配合缆载吊机进行无水平牵引力"荡移"施工。加劲梁吊装过程中,索鞍设置预偏量并通过顶推复位。结合加劲梁节段的吊装顺序,航道采用动态布置。

The main bridge of the Yingwuzhou Changjiang River Bridge in Wuhan is a threetower and four-span suspension bridge with span arrangement(200+2×850+200)m and the stiffening girder of the main bridge is the steel and concrete composite girder.In the erection of the stiffening girder,the girder was lifted and installed in segments by the 500 thydraulic cable-supported cranes and the largest segment that was lifted and installed weighed about 450 t.Before the segments of the side spans of the bridge were lifted,the concrete deck slabs and the steel girder were composited and before the segments of the central spans were lifted,the deck slabs and the girder were temporarily fixed and were lifted and installed together.The concrete for the wet joints of the deck was cast unless and until the whole bridge was closed.Totally 4sets of the cable-supported cranes were put in operation in the erection of the stiffening girder of the whole bridge.Each 2sets of the cranes were firstly arranged respectively over the 2central spans and after about3/4segments of each central span were lifted and installed,each 1set of the crane was respectively shifted to each side span and the lifting and installation of the remaining segments were then completed by the cranes.For the segments not to be supported by the permanent suspenders at the tops of the lower cross beams of the side towers,the segments were installed on the new type of the back-to-back tied pier-side brackets while for the erection of the stiffening girder of the special segments restricted by the assembling site,the segments were lifted and installed by the cable-supported cranes aided by the permanent suspenders in a way of'swaying'of the zero horizontal hauling force.In the lifting and installation of the segments of the stiffening girder,the pre-offsetting amounts for the tower saddles were set and the saddles were to be restored to their positions by pushing and for the sequences of the lifting and installation,the ship channels were maintained dynamically.