自锚式悬索桥主缆锚固结构研究

自锚式悬索桥以其结构造型美观和对地形和地质状况适应性强等优点,成为城市里100~400m跨径范围内极具竞争力的桥梁方案。三汊矶湘江大桥是一座主跨328m的大跨度自锚式悬索桥,主缆通过钢锚箱锚固在加劲梁两端。由于主缆直接锚固在加劲梁的两端,设置合理的锚固结构以保证主缆与加劲梁连接的强度、刚度、稳定性和主缆的轴力平顺传递,成为自锚式悬索桥设计的关键问题之一。总结钢自锚式悬索桥主缆的三种锚固型式:混凝土结构锚固、钢结构锚固和环形锚固,分析各自的优缺点和适用范围。对三汊矶湘江大桥的主缆锚固结构进行空间有限元分析和13∶.2大比例模型试验。计算和试验结果都表明,在设计索力状态下,锚固结构各构件的应力在70~130MPa之间;在1.6倍超载索力状态下,应力都在200MPa以下。验证大桥锚箱式锚固结构的安全性和可靠性,为自锚式悬索桥锚固结构的设计提供直接的指导。

Cable anchorage structure of self-anchored suspension bridge

Self-anchored suspension bridge,in the span range of 100m to 400m,has been recognized as a cost-effective and favorable scheme in urban areas,due to its elegant appearance and adaptability to geological and topographic conditions.The Sanchaji bridge is a self-anchored suspension bridge with a main span of 328m.The main cables are secured to the stiffening girders via steel anchor boxes,to ensure the strength,stiffness,stability and load transfer of the cable-girder connection.The design of cable-girder anchorage structure has become one of the most critical issues for self-anchored suspension bridges.Three cable anchorage systems,i.e.concrete anchorage,deck anchorage and loop cable anchorage systems are summarized,and their advantages,disadvantages and serviceability are investigated.A 3-D FEM analysis of the anchorage zone and a large scale(1:3.2) model test are carried out to verify the safety and reliability of the cable anchorage system.The calculation and test results indicate that the stresses of the anchorage structure are in the range of 70 MPa to 130 MPa under the design load,and below 200MPa with 1.6 times overload.The findings reported in the present paper may provide a guideline for design of the cable anchorage structure of the self-anchored suspension bridge.