索塔锚固区“U”形环向预应力伸长量不均匀性探讨

Discussion on Non-uniformity of U-Looped Prestressing Tendons Elongation at Tower Anchorage Zone

大吨位小半径"U"形环向预应力在混凝土斜拉桥锚固区中得到了较为广泛的应用,但目前的研究只是定性地认为钢铰线伸长量和受力存在不均匀性,不均匀的程度并未研究清楚。在前人的基础上,笔者设计了一种不均匀性的测试方法,借助统计手段,通过梅溪河斜拉桥索塔锚固区足尺模型试验研究了小半径"U"形环向预应力伸长量不均匀性和由此引起的预应力钢筋受力的不均匀性,研究认为小半径"U"形环向预应力伸长量和受力不均匀存在必然性,且群锚中钢铰线根数越多,这种不均匀程度越严重,张拉控制应力限值不宜再按现行桥梁设计规范取值,应适当降低。

Large-tonnage-and-small-radius U-looped prestressing tendons（ UPTs for short）have been widely used in the anchorage zone of cable-stayed bridge tower. However, only the research that the elongation of steel hinge line and tensile stress has non-uniformity is carried out in current study and the level of elongation and tensile stress non-uniformity has not been cleared. A novel method to test the non-uniformity is proposed, which is by virtue of the statistical method. The non-uniformity of small-radius UPTs elongation and tensile stress is studied by the full-scale model test of the tower anchorage zone at one cable-stayed bridge. The research draws the conclusion that the non-uniformity of small-radius UPTs elongation and tensile stress is certain to exist, and the non-uniformity level increases with the number of steel hinge lines. When UPTs prestressing system is used, the tension stress limit should not be controlled by the current bridge design specification, and the value of that should be reduced appropriately.