香山大桥珠海侧钢桁梁顶推支架设计

Design of Incremental Launching Bracket of Steel Truss Girder on Zhuhai Side of Xiangshan Bridge

摘要:

广东省中山东环高速公路香山大桥为（136+312+880+312+136）m双塔半飘浮体系双层桥面钢桁梁斜拉桥。大桥主跨跨越横门水道，两岸地势开阔，边跨及部分主跨梁段采用顶推法施工。珠海侧顶推钢桁梁长600.1 m，顶推总重量约3 万t，荷载集度大。首先，采用MIDAS软件建立顶推全过程有限元模型，确定了支架设计荷载；其次，拟定了构件设计参数；接着，建立多个有限元模型验算了桥面吊机静载试验及顶推过程中最不利工况下各支架的整体强度、刚度和稳定性，承重梁、分配梁、垫梁-斜撑、柱帽、立柱-斜撑、桩帽等关键构件局部强度。最后，验算了基础承载力。计算结果表明：支架各项指标满足规范要求。顶推实施过程结构安全，施工顺利。

Abstract:

Xiangshan Bridge in Zhongshan East Ring Expressway is a (136+312+880+312+136)-m double-pylon semi-floating system double-deck steel truss cable-stayed bridge. The main span of the bridge spans the Hengmen Waterway and the terrain on both sides is open. The side spans and the part of main span girder segments are constructed by the incremental launching method. The steel truss girder by the incremental launching method at Zhuhai side is 600.1 m long, the total incremental launching weight is about 30 000 t and the load concentration is high. Firstly, a finite element model of the whole incremental launching process is established by using Midas software to determine the design load of brackets. Secondly, the component design parameters are proposed. Then, several finite element models are established to calculate and check the overall strength, stiffness and stability of each bracket under the static load test case of the deck crane and the most unfavorable cases during incremental launching, as well as the key local strength of the bearing beam, distributive beam, cushion beam - brace, column cap, column - brace, pile cap, etc. Finally, the bearing capacity of the foundation is checked. The calculation results indicate that all indicators of brackets meet the requirements of the specifications. The structure is safe and the construction is smooth during the incremental launching process.