平行钢丝拉索承载力评定  

Bearing capacity assessment for parallel wire cables

作　　者：兰成明[1] 李惠[2] 鞠杨[3] 

机构地区：[1]北京科技大学国家材料服役安全科学中心,北京100083 [2]哈尔滨工业大学,黑龙江哈尔滨150090 [3]中国矿业大学,北京100083

出　　处：《土木工程学报》2013年第5期31-38,共8页China Civil Engineering Journal

基　　金：国家自然科学基金(51008302;51125017);国家重点基础研究发展计划973计划(2010CB226804;2011CB013604);中央高校基本科研业务费专项资金(FRF-TP-13-037A)

摘　　要：依托国内某大跨径斜拉桥换索工程,对服役18年的拉索内钢丝锈蚀程度和力学性能进行测试,探讨腐蚀对钢丝强度及延性的影响。根据单根钢丝强度的概率分布采用统计强度理论建立平行钢丝拉索承载力评定方法,研究长度效应和Daniels效应对整根拉索承载力的影响规律。研究表明:钢丝名义强度的减小主要由于腐蚀导致钢丝截面面积减小造成的,腐蚀导致钢丝的延性显著降低;单根钢丝的极限强度服从Weibull分布,随着比例参数的增加(即钢丝相关长度减小),钢丝的强度逐渐降低;随着平行拉索内钢丝数的增加,拉索强度均值减小率趋于固定值,拉索强度的变异系数渐近于0,拉索的强度趋于固定值;腐蚀拉索承载力降低是由腐蚀导致钢丝截面面积减小和腐蚀导致相关长度减小造成的,有可能后者的影响比前者还大。Corroded cables with 18-year service life on a large-scale cable-stayed bridge are employed to investigate the corrosion extent and the mechanical properties of wires. The influence of corrosion on strength and ductility of wire are discussed. The bearing capacity assessment method of parallel wire cable is established based on the statistical strength theory and probability distribution of single wire strength. The numerical simulation of influence laws of length effect and Daniels effect on the cable strength is conducted. The experimental results indicate that the cross-section loss caused by corrosion is the main reason of nominal strength reduction of steel wire. Furthermore, corrosion can significantly reduce the ductility of steel wires. Ultimate strength of single wire obeys the Weibull distribution, and the ultimate strength decreases with the increase of scale parameters. With the increase of wire number in cable, the bearing capacity reduction ratio of cable tends to be constant and the variation coefficient of cable strength approaches zero. Cross-section loss and correlation length reduction of the cable due to corrosion are the two main reasons for reduction of cable bearing capacity. Sometimes, the latter has bigger influence than the former.

关 键 词：平行钢丝拉索 腐蚀 WEIBULL分布 Daniels效应 长度效应 

分 类 号：U448.2[建筑科学—桥梁与隧道工程]