摘要
甘溪特大桥为主跨300m的空腹式刚构桥,双幅布置,单幅主梁为单箱单室预应力混凝土结构。空腹三角区总长约120m,比选其施工方案后,确定选择上弦设置活动立柱支顶配合挂篮悬浇、下弦设置扣索配合挂篮悬浇的施工方案。临时支撑立柱主体结构采用?630mm×10mm钢管,顶端设计为可伸缩式端头。边、中跨下弦对称节段之间设置对拉临时扣索,扣索采用15-19、15-25两种规格的钢绞线束。上、下弦箱梁单侧共13个节段,采用挂篮浇筑。上弦5~12号节段未设置悬浇预应力下弯束,已浇箱梁节段腹板下方支顶钢管立柱进行支撑。下弦领先上弦2个节段施工,浇筑后对称张拉已浇箱梁节段对应的临时扣索。上、下弦交汇段(13号节段)分2次浇筑,混凝土施工缝设于交汇段圆弧中间高度处。
The Ganxi Bridge is an open-web rigid frame bridge with a main span of 300 m.The bridge has two parallel decks,each containing mono-cell prestressed concrete box girders.The open-web triangular zone has a total length of about 120 m.After comparison of construction schemes,it was determined that the upper chord be cast by using form travellers with the aid of movable supporting columns,and the lower chord be cast by using form travellers with the aid of fastening stays.The temporary vertical column is made of steel tubes with dimension of?630 mm×10 mm,with retractable top ends.Between the symmetrical segments of the upper and lower chords,the temporary fastening stays that can be pulled from two ends are installed.The fastening stays incorporate the 15-19 and 15-25 types of steel strands.Both upper and lower chords on each side consist of 13 segments,cast by form travellers.For the segments 5-12 of the upper chord,no lower bending prestressing tendons are included.The already-cast segments were supported on steel tubular columns under the webs.The construction of the lower chord was two segments ahead of that of the upper chord,after the completion of casting,the temporary fastening stays between the symmetrical upper and lower segments were tensioned.The converging segment of the upper and lower chords,namely the segment 13,was cast by two times,with the concrete stitch located at the height near the central part of the arc of the converging segment.
作者
孙克强
李松
李百富
韦玉林
刘民胜
SUN Ke-qiang;LI Song;LI Bai-fu;WEI Yu-lin;LIU Min-sheng(CCCC Second Highway Engineering Co.,Ltd.,Xi′an 710065,China)
出处
《世界桥梁》
北大核心
2020年第2期45-50,共6页
World Bridges
关键词
空腹式刚构桥
三角区
挂篮悬浇
临时扣索
支撑立柱
施工方案
open-web rigid frame bridge
triangular zone
cantilever casting by form traveller
temporary fastening stay
supporting column
construction technique
