合龙温差下部分斜拉桥顶推力的确定

Determination of Jacking-force of Extradosed Bridge Considering Final Closure Temperature Differences

在斜拉桥施工过程中,由于实际合龙温度与设计合龙温度不一致而引起部分斜拉桥发生位移及温度内力,从而极易导致合龙偏差问题。为此本文以某特大桥工程为依托,建立结构有限元分析模型,以设计合龙温度20℃为基准,以实际可能的合龙时段温度21~39℃为分析参数,提出以不同内力值为目标值消除温度附加内力的顶推力优化分析方法。研究结果表明：曲线部分斜拉桥的主梁内力、位移与合龙温差呈线性增长关系;合龙温差对曲线部分斜拉桥产生的扭矩及侧弯值可以忽略不计;以消除塔墩梁固结处主梁位移为目标确定合理顶推力的效果较好,其塔墩梁固结处主梁位移及墩底弯矩消除量可分别达到合龙温差作用的98%及78%,利于控制成桥线形;实际施工中应依照力学性能施加偏心顶推力。研究成果可为此类桥梁合龙时顶推力的施加提供参考意义。

During extradosed bridge construction,the differences between actual closure temperature and design closure temperature may cause vertical displacement and internal forces,which will further cause final closure deviation problem. Structure finite element analysis mode was established based on an extradosed bridge. Based on design temperature 20℃,this paper set actual possible closure temperature 21℃ ~ 39℃ as analysis parameter,a closure jacking-force optimization analysis method was proposed,use different internal force value as target to eliminate temperature additional internal forces. The results showed four conclusions. Firstly,internal force and displacement of girder in addition of closure temperature differences were linear growth relations of extradosed bridge. Secondly,the influences from closure temperature difference on torque and lateral bending of curve extradosed bridge may be ignored. Thirdly,determine closure jacking-force by eliminate the beam displacement in consolidation may get the best effect,the elimination of beam displacement and pier bending moment may separately achieve 98% and 78% after jacking force applied,and which is good for bridge linear control. Finally,eccentric jacking force should be applied based on mechanical properties in actual construction. Research results can be used to guide similar bridge closure jacking force.