大跨度外倾式非对称系杆拱桥施工监控研究

Study of Construction Monitoring and Control of Long-Span Tied Arch Bridge with Asymmetrical Splayed Arch Ribs

南宁大桥为主跨300m的外倾式非对称系杆拱桥,钢拱肋和钢箱梁采用"先拱后梁、无支架缆索吊装"施工方案。为确保结构在施工过程中的安全,并使其成桥内力及线形符合设计要求,通过建立有限元模型进行施工过程的分阶段计算,并对施工过程中混凝土拱肋、钢拱肋、钢箱梁及塔架的应力和位移,承台的沉降,扣锚索、横拉索、吊杆、系杆、主缆及起重索的索力等进行现场监控。施工监控结果表明:结构的内力和线形均满足设计要求,与设计理想状态吻合较好;整个过程安全可控。

Nanning Bridge is a tied arch bridge with asymmetrical splayed arch ribs and with a main span of 300 m. The steel arch ribs and steel box girder were constructed by the scheme of ＂erecting the arch ribs first and the girder later by way of cable crane hoisting and installing with- out the aid of scaffoldings＂. To ensure the safety of the structure in the construction process and to make the mechanical behavior and geometrical shape of the bridge in the finished bridge state meet the design requirements, the finite element model of the bridge was set up to do the step-by- step calculation of the construction process as well as conduct in-situ monitoring and control of the stress and displacement of the concrete arch ribs, steel arch ribs, steel box girder and the lift- ing tower, the settlement of the pile caps, and the force of the fastening anchor cables, transverse pull-back cables, hangers, main cables and lifting ropes. The results of the construction monito- ring and control indicated that the mechanical behavior and geometrical shape of the structure all met the design requirements and agreed well with the ideal design condition, and the whole con- struction process was safe and controllable.