大跨连续刚构桥预应力张拉顺序影响分析

Influence Analysis of Prestressed Sequence of Long-span Continuous Rigid Frame Bridge

为了确保连续刚构桥施工过程中结构受力合理及安全,以龙溪嘉陵江特大桥为工程背景,分别对其上部结构在挂篮悬浇阶段及中跨合龙阶段在不同预应力张拉方案下的结构受力和变形情况进行分析。结果表明,挂篮悬浇阶段先张拉腹板束能减少主梁拉应力产生的可能性;中跨合龙钢束无论采用先对称张拉长束还是先张拉短束,结构受力均较合理,但后者对主梁线形影响较大。通过在实际施工中的应用,并结合现场施工过程监控,主梁受力始终较好。

In order to ensure that the construction process of continuous rigid frame bridge structure stress is reasonable and safe, the structural stress and deformation of its superstructure under different prestressed tensioning schemes at the bask-hanging casting stage and mid-span closing stage are analyzed respectively based on the engineering background of Longxi Jialing River Bridge. The calculation and analysis results show that the possibility of main tensile stress can be reduced by firstly tensioning the web bundle in the hanging casting stage, the structural stress of the middle span closing steel beam is reasonable whether the symmetrical tensioned beam is used firstly or the short tensioned beam is used firstly, but the latter has a great influence on the girder alignment. Through the implementation in the actual construction, combined with the monitoring of the site construction process, the stress of the main girder is always good.