混凝土自锚式悬索桥超宽加劲梁施工过程受力分析

Mechanical analysis on construction process of extra wide stiffening girder of self-anchored concrete suspension bridge

【目的】研究混凝土自锚式悬索桥超宽加劲梁在施工过程中的应力分布规律,为超宽加劲梁的设计与施工提供一定的理论依据。【方法】采用剪力柔性梁格法,通过Midas/Civil建立空间有限元梁格模型,对自锚式悬索桥加劲梁受力性能进行分析。【结果】在施工过程中,加劲梁横截面各腹板处顶、底板中纵向应力的分布存在较大的不均匀性,预应力张拉工况中,加劲梁外侧边腹板处压应力最大;体系转化工况中,中腹板处压应力增量最大。体系转换过程中加劲梁顶、底板的应力变化规律不同,顶板中的压应力值在体系转换完成后达到最大,底板最大压应力值则出现在体系转换过程中。施加二期恒载,对吊索进行被动张拉,能够有效地减少主动张拉吊索过程产生的顶、底板应力差值。【结论】主缆轴力与预应力作用是造成加劲梁内应力分布不均的主要原因,通过调整预应力钢束的数量及位置,能够使加劲梁内应力分布更均匀。

【Objective】Studying the stress distribution of an extra-wide stiffening girder of a concrete self-anchored suspension bridge,during the construction process,could provide theoretical reference for its design and construction.【Method】The shear flexible beam grid method was used to establish a finite element beam grid model in space with a Midas/Civil system.Further,the performance of stiffening girder under loading was analyzed.【Result】The transverse stress distribution in the top and bottom plates of the stiffening girder demonstrated an obvious non-uniformity.In the process of pre-stressing,the stress on the outer webs of the girder was larger than that on the inner webs.In the process of system conversion,the stress increment on inner webs was larger.It was during the process of system conversion that the stress variations in the top and bottom plates of the stiffening girder were different.The maximum compressive stress in the bottom plate was recorded in the hanger tensioning process.Therefore,in the top plate,the compressive stress reaches a maximum after system conversion,while in the bottom plate,the compressive stress reaches a maximum during the process of system conversion.As a passive tensioning process of the hangers,the application of second-phase constant load could significantly reduce the stress difference between the top and bottom plates caused by the initial hanger tension.【Conclusion】The main reason for the non-uniformity in the transverse stress distribution was investigated to be the axial force in the main cable and the action of pre-stressed tendons.The stress distribution in the stiffening girder could be made uniform by adjusting the number and position of pre-stressed tendons.