竖向预应力作用效果的数值模拟与预应力损失的试验研究

对箱梁竖向预应力筋张拉引起的混凝土竖向应力和螺纹钢筋的应力进行了有限元计算和现场测试分析,测试结果表明预应力损失离散性很大,而且预应力损失可能高达50%.这是由于箱梁的高度有限,竖向预应力筋的长度都比较短,因而在达到张拉控制应力时高强精轧螺纹粗钢筋的伸长量有限.目前的竖向预应力锚固技术尚存在不足,在锚固时稍有不慎造成钢筋回缩量偏大,很容易造成预应力损失.

Numerical Simulation on Vertical Prestressed Effect and Experimental Studies on Prestressed Loss

The vertical stress in concrete and the stress of thread reinforcing bar are calculated by FEM and are measured.That is made by stretch the vertical prestressed bar in the box girder.It shows that prestressed loss is with high discreteness and prestressed loss may be as high as 50 percent.Because the height of box girder is limited,vertical prestressed bar is short,so when control stress of prestressing is attained,elongation of thick high strength thread reinforcing bar is limited.Up till now,the techniques of the vertical prestressed anchorage is still inadequate.While anchoring,without high discretion,the retraction of tendons will be large and the prestressed loss will be produced easily.The department of design and construction should take the phenomenon seriously.