预应力混凝土斜拉桥合龙段置换加固施工过程分析

预应力混凝土斜拉桥合龙段置换加固技术是为解决合龙段与相邻主梁节段之间的湿接缝失效问题而提出的。为分析这种加固技术的受力特点,介绍了这种加固技术的实现途径和施工要点,建立了典型的预应力混凝土斜拉桥的结构计算模型,系统地给出了施工阶段分析的方法,包括合龙段置换的结构基准计算模型的建立和合龙段置换施工过程的模拟,依据计算结果,分析了合龙段置换过程中桥面线形、索力以及塔顶偏位等结构状态参数的变化。研究表明,采用该方法能够反映斜拉桥结构状态的实际变化历程和现状检测结果,模拟计算结果与合龙段置换施工监测结果较为吻合,从而揭示了合龙段置换施工过程结构的变化特点,可为预应力混凝土斜拉桥合龙段置换加固的设计计算和施工控制提供依据。

Construction Stage Analysis on Replacement of Closure Segment in Prestressed Concrete Cable-stayed Bridges

To deal with failure of wet joint between a closure segment and its neighboring segments of main girder in an existing prestressed concrete cable-stayed bridge,the technology on replacement of closure segment was presented.In order to analyze structural characteristics of this technology,its technical approaches and construction key points were introduced.Then a FEM model for a typical prestressed concrete cable-stayed bridge was established,and a construction stage analysis method was given in detail,including establishing a structural basement calculation model for replacement of closure segment and simulating its construction procedures.Based upon calculation results,variations of some structural state parameters with construction stages,such as deck deflection of main girder,longitudinal horizontal displacement at the top of pylons,cable forces,were analyzed.The results showed,this method could reflect actual change process of structural state and existing inspected results of cable-stayed bridge,and FEM results could well meet with construction monitoring results during replacement of closure segment.Thus variations of structural characteristics with construction stages could actually be revealed.This method could provide references for design and construction control of replacement of closure segment in existing prestressed concrete cable-stayed bridges.