PC系杆拱桥施工阶段稳定性及临时横撑影响分析

为有效指导PC系杆拱桥的施工,对该类桥梁施工阶段的稳定性及临时横撑对结构稳定性的影响进行研究.以江苏省新建省道336公路桥为背景,采用MIDAS Civil建立桥梁空间有限元模型,对3个施工控制阶段结构的稳定性及临时横撑设置与否、设置位置及形式对暂态拱稳定性的影响进行分析.分析结果表明:该桥施工阶段具有较好的稳定安全系数；施工阶段的吊杆张拉对全桥的稳定性有负影响；对称设置临时横撑时,同类型横撑设置在1/4跨径处效果最为明显；在相同位置设置X形临时横撑对结构稳定性贡献最大；横撑的间距和形式选择还需综合考虑桥梁美学、经济性及施工方便.

Analysis of Stability and Influences of Temporary Cross Bracings of PC Tied Arch Bridge at Construction Stages

To provide effective guidance for the construction of prestressed concrete(PC) tied arch bridge,the stability of the bridge of the same type and the influences of temporary cross bracings on the stability at construction stages were studied.The Highway Bridge 336 on the Provincial Route,Jiangsu was cited as an example,the MIDAS Civil was used to create the spatial finite element model for the bridge,the stability and influences of setting or not setting the temporary cross bracings,positions and types of the bracings at three construction stages on the stability of the arch in temporary status were analyzed.The results of the analysis show that the bridge at the construction stages has good stability safety coefficients.At the construction stages,the tensioning of hangers has negative influence on the stability of the whole bridge.When the temporary cross bracings are symmetrically set,the effect of the bracings of the same type set at 1/4 span is most obvious and the contribution of the X-shape temporary bracings set at the same positions to the stability is the greatest.However,for selection of the spacing distance and types of the bracings,the factors of the aesthetics,economy and construction convenience of the bridge should be comprehensively considered.