大跨度斜拉桥索塔锚固区应力分析

Stress Analysis of Anchorage Zone on Tower of Long-span Cable-stayed Bridge

斜拉桥拉索锚固区是索塔受力的关键部位,在斜拉索大吨位拉力及预应力共同作用下,受力十分复杂,保证其结构安全、受力合理是斜拉桥建造过程中的关键问题。运用实体有限元方法对某斜拉桥索塔锚固区进行空间应力分析,对比分析了3种不同工况下锚固区的受力特点及应力分布规律。分析结果表明,采用环向井字形的水平预应力束配置形式是合理的;在1 265MPa的张拉控制应力下,各钢束应力都已经相当接近1 116MPa,说明了预应力钢束的强度已经充分发挥,不宜再提高张拉控制力。

Anchorage zone on tower of cable-stayed bridge has complex structures and stress distributions, and keeping it on a safety state under a large tonnage tension and prestress is more concerned in design and construction. The stress distribution of the anchorage zone was analyzed by 3D finite element method. Furthermore, the mechanical properties and the rules of stress distributions were investigated and compared in three different load cases. The results show that the disposition form of level prestressing tendon is reasonable. The stress of the entire tendon is very close to 1 116 MPa under the tension control stress of 1 260 MPa. It is shown that the intensity of the tendon has given full play to prestress and it is not appropriate to increase the tension control stress.