摘要
为了减小斜拉桥曲线形钻石桥塔在施工阶段和运营阶段的拉应力,防止混凝土桥塔出现开裂病害,以主跨480m的宜宾盐坪坝长江大桥为例,开展桥塔抗裂设计技术研究。采用MIDAS Civil程序建立全桥空间有限元模型,计算桥塔在施工阶段和成桥运营状态下的内力,研究桥塔竖向预应力、斜拉索横向偏心布置、塔柱临时横撑及对拉、环向预应力等措施对桥塔应力的改善作用,以及桥塔混凝土掺加钢纤维对材料强度的提升效果。结果表明:曲线形钻石桥塔受力复杂,在塔柱受拉区设竖向预应力是有效的抗裂措施;斜拉索适当向曲线外侧横向偏心布置可减小塔柱横向弯矩;临时横撑及对拉既可减小施工期塔柱拉应力,又可改善塔柱成桥状态的应力;环向预应力为塔柱水平方向提供一定压应力储备;桥塔混凝土中掺加少量钢纤维对强度提升作用不大,可减小桥塔表面非受力裂缝。
To reduce the tensile stress in the diamond-shaped curved pylon of cable-stayed bridge in the construction and operation stages and prevent the concrete pylon from cracking, the Yanpingba Changjiang River Bridge in Yibin with a main span of 480 m was cited as an example, to study the anti-cracking design techniques for the pylon. MIDAS Civil was used to establish the spatial finite element model of the overall bridge, to calculate the internal force of the pylon in both the construction stage and the operation state of the completed bridge. The functions of vertical prestress in the pylon, transverse eccentric arrangement of stay cables, temporary cross beam of the pylon and the pull-back and loop prestress on the improvement of the stresses in the pylon were studied. The effect of mixing steel fibers into the pylon concrete was examined. The results show that the load bearing condition of the diamond-shaped curved pylon is complicated, and placing vertical prestress in the tensile area of the pylon columns is an effective anti-cracking measure. To transversely move the stay cables a little towards outer of the curves can reduce the transverse bending moment of the pylon column. Adding temporary cross beams and tensioning prestressing tendons from two opposite directions can not only reduce the tensile stress in the pylon columns during the construction process, but also improve the stresses in the pylon columns in the completed bridge state. Loop prestressing can provide compressive stress storage in the horizontal direction for the pylon columns. Mixing a little amount of steel fibers has minimal effect on the improvement of pylon concrete strength, but can reduce the cracks on the pylon walls that are not induced by loads.
作者
蒋建军
田波
何锋
陈原
JIANG Jian-jun;TIAN Bo;HE Feng;CHEN Yuan(Sichuan Highway Planning, Survey, Design & Research Institute Ltd. , Chengdu 610041, China)
出处
《世界桥梁》
北大核心
2019年第4期12-16,共5页
World Bridges
关键词
斜拉桥
曲线形钻石桥塔
混凝土结构
抗裂设计
临时横撑
钢纤维混凝土
有限元法
cable-stayed bridge
diamond-shaped curved pylon
concrete structure
anti-cracking design
temporary cross beam
concrete with steel fibers
finite element method
