大跨度高铁斜拉桥钢-混结合主梁收缩徐变研究

为研究钢混结合主梁混凝土桥面板的收缩徐变对大跨度高铁无砟轨道斜拉桥的影响,以昌吉赣客专赣江特大桥为工程背景,采用Midas Civil软件建立全桥精细化数值分析模型,考虑钢混结合梁混凝土桥面板不同的加载龄期,分析结合梁斜拉桥在收缩徐变效应下变形及受力的变化。结果表明:赣江特大桥结合梁在施工成桥初期至运营5年后,钢混结合梁混凝土桥面板收缩徐变引起面板及钢箱梁的应力变化情况均满足规范要求,桥面板及钢箱梁在施工成桥1年后收缩徐变完成50%以上,3年后完成80%左右;桥面板混凝土的加载龄期越长,混凝土收缩徐变对桥梁结构变形和受力的影响越小,并在混凝土加载龄期达到180 d后对桥梁结构的影响呈稳定趋势,将结合梁桥面板预制存放180 d后再进行吊装,可有效降低混凝土收缩徐变对此种结构正常使用期间力学行为的影响。

Research on Shrinkage and Creep of Composite Girder for Long-span High-speed Railway Cable-stayed Bridge

In order to study the influence of shrinkage and creep of the steel-concrete composite girder concrete deck of long-span high-speed railway cable-stayed bridge with ballastless track,taking Ganjiang bridge of Changji passenger dedicated line as an example,a numerical analysis model of the bridge was established by Midas Civil software.Considering the different loading age of the concrete deck,the deformation and stress changes of composite beam cable-stayed bridge under the effect of shrinkage and creep were analyzed.The result shows that:from the initial stage of construction to 5 years of operation,the stress changes of concrete deck and steel box girder caused by shrinkage and creep of steel-concrete composite beam meet the requirements of specifications;the shrinkage and creep of bridge deck and steel box girder are more than 50%after 1 year of construction and 80%after 3 years of operation;the longer the loading age of bridge deck concrete,the more shrinkage of concrete and smaller the influence of creep on the deformation and stress of the bridge structure,and the more stable the influence on the bridge structure after the loading age of concrete reaches 180 days.The influence of concrete shrinkage and creep can be effectively reduced in terms of the mechanical behavior of the structure during normal use by prefabricating and storing the combined beam deck for 180 days before hoisting.