大跨径预应力混凝土连续梁桥竖向预应力钢棒的应用

Application of Vertical Prestressed Steel Bars to the Long-span Prestressed Concrete Continuous Beam

大跨径预应力混凝土连续梁桥普遍存在梁体下挠和腹板开裂的问题,造成该问题的主要原因之一是连续梁桥竖向预应力损失严重。结合武汉市西四环高速公路通顺河大桥,尝试使用无粘结预应力钢棒,解决传统精轧螺纹钢筋松弛性差、回缩损失大,张拉力和理论伸长量不符、预应力筋易产生腐蚀、施工繁琐等问题。与传统竖向预应力精轧螺纹钢筋相比,无粘结预应力钢棒具有材料性能优异,施工工艺简单,验收方法可靠,易实施等优点。

At present,the problems of beam deflection and web cracking can easily be found in the long-span prestressed concrete continuous beams;one of the main causes is that the loss of vertical prestress in the continuous beams is too large.Based on the engineering example ofTongshun Bridge onWuhan West Fourth Ring Highway,an unbonded prestressed steel bar is introduced in this paper,and the product can effectively solve the problems caused by traditional finishing rolling rebar,like the rebar relaxation,retraction loss,discrepancies betweentension and theoretical elongation,prestressed reinforcement corrosion and the complex construction.Compared with the traditional vertical prestressed rebar,the unbonded prestressed steel bar hastheadvantages of excellent performance material,simple construction process,reliable inspection method and easy implementation.