钢桁-混凝土连续刚构协作体系桥梁顶推效应研究

Effect of Jacking Force on Combined Steel Truss and Concrete Continuous Rigid-Frame Bridge

为了研究合龙顶推工艺对铁路大跨钢桁-混凝土连续刚构协作体系桥梁长期变形的影响,建立了合龙顶推的分析模型,提出了基于桥墩侧移量的顶推力反演修正准则;并以某在建高速铁路大跨钢桁-混凝土连续刚构协作体系桥梁为背景,分析顶推力对主梁竖向下挠和桥墩弯矩的影响,以及钢桁架与顶推力对主梁下挠的影响比例关系。结果表明:合理的顶推力可以显著改善桥墩受力状态,并有效缓解主跨跨中下挠;钢桁架减小主跨跨中挠度的幅度相比顶推力较小,但对边跨的变形是有利的。建议综合考虑顶推效应和钢桁架来改善高速铁路混凝土连续刚构桥主梁下挠。

For the long-span railway bridge of a combined steel truss and concrete continuous rigid-frame system,the jacking techniques used in the closure process are likely to exert influence on the long-term deformation of the bridge.Studies have been carried out to make clear this influence.In this paper,the closure jacking process was numerically simulated,based on which the inversed and revised criterion dependent on lateral displacements of piers is proposed.A highspeed railway bridge of the similar type that is currently under construction was cited as a case.The influence of jacking force on the vertical deflection of main girder and bending moments of piers was analyzed,and the proportional relationships between main girder vertical deflection and steel truss as well as jacking force were discussed.The results show that reasonable jacking force can significantly improve the stress state of the pier and effectively mitigate midspan vertical deflection in the main span.Compared with jacking force,steel truss exerts relatively smaller influence on the reduction of midpan vertical deflection in the main span,but can alleviate the deformation of side spans.It is suggested that the influence of jacking force and steel truss be considered and integrated to improve the vertical deflection of main girder of the concrete continuous rigid-frame bridge on high speed railway.