合龙方案对多跨连续梁桥施工监控的影响分析

多跨连续梁的合龙顺序对结构成桥累计位移和内力有较大影响,以1座(48+4×80+48)m预应力混凝土连续梁桥为例,根据不同的合龙方案确定3种工况,对不同工况下的桥梁结构建立不同结构体系转换的施工阶段分析有限元模型,分析合龙顺序及合龙期间的预应力张拉阶段对施工阶段的预拱度及成桥内力的影响,对比分析多跨连续梁桥合龙口两端产生较大位移差的原因。提出多跨连续梁桥线形监控难度的主要影响因素为累计位移最大值和合龙口两端的累计位移差。结果表明,合龙顺序对梁体施工中的预拱度设置量影响较大,特别是不同结构体系下预应力张拉效应差别较大,合理的合龙顺序和分批分阶段张拉预应力可降低施工过程中线形监控的难度,根据分析结果提出合理的合龙顺序建议。

Research on the Effect of Closure Program on Construction Monitoring of Multi-span Continuous Beam Bridge

The closure order of multi-span continuous beam often exerts eminent influence on the cumulative displacement and internal force of the bridge structure. With reference to a pre-stressed concrete continuous beam bridge of( 48 +4 ×80 +48) m,finite element models are established with respect to three different conditions according for each different closure program to analyze the effects of closure order and pre-stress tensioning in the process of closure on the camber and the internal force during the construction and the causes of displacement difference between the closure ports. It is concluded that the main influencing factors impacting the monitoring are the maximum accumulated displacement and the accumulated displacement difference between closure ports. The results indicate that the setting of camber is greatly influenced by the closure order,especially,the difference in pre-stressed tensioning effect for different structural systems is very big. As reasonable closure order with phased pre-stressed tensioning may facilitate the linear control in construction process,reasonable closure order is proposed based on analysis results.