对外交通公路三座钢管混凝土拱桥设计

三峡工程对外交通专用公路上的黄柏河、下牢溪特大桥主桥系上承式倒悬链线无铰钢管混凝土拱桥，设计载为汽36，跨度均为160m，采用有平衡重的平面转体法施工。钢管在工厂卷制焊接成大管节，在工地拱架上拼装成半拱，然后转体合拢，转角105～180°。转体由下盘、球铰、上盘及其上的预应力墩柱、半拱、拉杆组成。转动采用同步连续不间断千斤顶进行。莲沱特大桥为中承式钢管混凝土桥，中拱采用竖转吊装合拢的施工方法。钢管表面防腐采用高效电弧喷涂为主的长效复合涂层，有效寿命可达20年。

Designs for Three Steel Tube Concrete Bridges

The main spans of Huangbaihe and Xialaoxi Outsize Bridges with a design load of 36t truck anda max. span of 160m, on the way of the special access road to the Three Gorges Project, are all deck-sus-pended chains-non-articulated steel tube concrete arch bridges erected by means of counterweight and horizontalturning. The steel plates were rolled, welded and fabracated to large cases in the workshop.Thesecases were assembled on the arch carriage on the site into half-arches which then were turned and butted ata 105-180 degrees. The turner, composed of chassis, ball hinges, support and prestressed column on it,half-arch and rods, was driven with jacks synchronously and continuously. The mid-arch of the LiantuoOutsize Bridge was lifted and butted with a vertical turning system. For resistance to corrosion, a long-termeffective composite paint up to 20 years of active life was mainly applied with a high effective are gun to thesurface of steel tubes.