港珠澳大桥九洲航道桥辅助墩支点顶升受力分析

港珠澳大桥九洲航道桥为主跨268m双塔单索面钢-混组合梁斜拉桥,辅助墩负弯矩区主梁采用支点顶升法施工。为研究该桥辅助墩支点顶升及回落施工对结构受力的影响,采用MIDAS Civil软件建立全桥空间有限元模型,分析顶升施工全过程中桥塔、主梁、斜拉索的受力。结果表明:顶升施工中桥塔、主梁变形较大,顶升回落后其变形基本恢复至顶升前状态;顶升施工中塔梁固结段位置处桥塔结构应力变化显著,桥面板后叠合区域的钢梁结构应力变化较为明显;顶升后斜拉索索力出现较大幅度的降低,顶升回落后斜拉索索力基本与顶升前索力相一致;支点顶升法能够有效地改善负弯矩区桥面板的受力情况,对负弯矩区施加预应力的效果明显。

Force Analysis for Jacking-Up Construction at Fulcrum of Auxiliary Piers of Jiuzhou Ship Channel Bridge of Hong Kong-Zhuhai-Macao Bridge

Jiuzhou Ship Channel Bridge of Hong Kong-Zhuhai-Macao Bridge is a cable-stayed bridge that has a stucture of double-pylon single-cable plane steel-concrete composite girder with a main span of 268 m.The jacking-up method at the fulcrum is adopted in the construction of the main girder in negative moment zone.In order to study the influences of jacking-up and falling at the fulcrum of the auxiliary pier on the stress of structures,we established a 3 Dfinite element model by using the software MIDAS Civil,and analyzed the stresses of the pylons,main girder and cables in the whole process of jacking-up construction.The results show that the pylons and main girder deform significantly in the jacking-up construction but almost recover to its previous state after the operation of falling;in the jacking-up construction,the stress of pylons in the rigid fixity section of pylon and girder varies significantly,and the stress of steel girder in the overlap area behind bridge deck varies moderately;the forces of stay cables decrease sharply after the jacking-up construction and can recover to the previous force state after the operation of falling;the structural stress of bridge deck in the negative moment zone is effectively improved due to the jacking-up construction,and the prestressing effect in the negative moment zone is obvious.