连续梁桥竖向预应力钢绞线二次张拉的应力损失分析
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摘要
近年来,大跨径预应力混凝土梁桥在施工过程或使用阶段,普遍出现各种不同性质的混凝土开裂,其中腹板斜裂缝的出现比例高达86%,裂缝的出现引起结构刚度的降低导致变形增大,同时腹板斜裂缝还会直接降低腹板本身的刚度50%以上,对桥梁的耐久性及使用安全性产生了很大的安全威胁。裂缝的发生一方面是运营荷载的变化,另一方面就是设计对竖向预应力空间效应考虑不足所致。针对官渡黄河大桥连续梁施工,研究二次张拉低回缩钢绞线竖向预应力锚固体系的预应力损失情况,为竖向预应力施工提供参考。
In recent years,during the construction process or use stage of large-span prestressed concrete girder bridges,concrete cracking of various properties has been common,in which the proportion of web oblique cracks is as high as 86%,and the occurrence of cracks causes structural rigidity to decrease. The deformation is increased,and the oblique crack of the web directly reduces the stiffness of the web itself by more than 50%,which poses a great security threat to the durability and safety of the bridge. The occurrence of cracks is on the one hand the change of the operational load,and on the other hand the design is insufficient to consider the spatial effect of the vertical prestress. According to the continuous beam construction of Guandu Yellow River Bridge,the prestress loss of the vertical prestressed anchor system of the secondary tension and retraction steel strand is studied,which provides a reference for vertical prestressed construction.
In recent years,during the construction process or use stage of large-span prestressed concrete girder bridges,concrete cracking of various properties has been common,in which the proportion of web oblique cracks is as high as 86%,and the occurrence of cracks causes structural rigidity to decrease. The deformation is increased,and the oblique crack of the web directly reduces the stiffness of the web itself by more than 50%,which poses a great security threat to the durability and safety of the bridge. The occurrence of cracks is on the one hand the change of the operational load,and on the other hand the design is insufficient to consider the spatial effect of the vertical prestress. According to the continuous beam construction of Guandu Yellow River Bridge,the prestress loss of the vertical prestressed anchor system of the secondary tension and retraction steel strand is studied,which provides a reference for vertical prestressed construction.
引文
[1]胡林翼.竖向预应力钢绞线二次张拉施工工艺研究[J].湖南交通科技,2016,42(2):200–203.
[2]李国平,黎金星.基于无应力长度目标的平行钢绞线斜拉索张拉方法[J].中国公路学报,2017,30(2):48–56.
[2]李国平,黎金星.基于无应力长度目标的平行钢绞线斜拉索张拉方法[J].中国公路学报,2017,30(2):48–56.