基于防腐和受力性能的钢-碳纤维(CFRP)组合缆索截面形式研究

Cable consisting of steel and carbon fiber reinforced plastic(CFRP) which possesses the advantages of the two kinds of materials is a new direction of cable in suspension bridge. However, its composition style, structural behavior and anticorrosive property have not been studied at present. Theoretical, numerical and experimental studies are conducted to acquire the style of cable section consisting of steel and CFRP with better anticorrosive property and mechanical property. Firstly, in order to get a more optimized area ratio of steel and CFRP in composite section, the influence of the area ratio on the static and dynamic stiffness is discussed. Basing on the area ratio, the composition style of steel and CFRP is proposed. Then the mechanical behaviors of composite section subjected to single and coupling of multi-loading mode including tension, bend, twist and so on are researched by theoretical and numerical analysis. According to the research results, the style of composition section is further optimized. Furthermore, the accelerated corrosion tests are carried out to investigate the anticorrosive property of the composition section in various corrosion environments which is made up by one of acid, alkali, salt, wet, tensile stress etc. and some of them. Finally, the features of composition section under the worst loading mode are summarized. And the key points of design of composition section under the worst corrosion environment are proposed. Taking into account the above research results, the size of cable and other factors, the optimization design theory of composition section of steel-CFRP is proposed. The research results could be used to solve cable corrosion and limited spanning capacity of suspension bridge, and it is very significant.

钢-碳纤维（CFRP）组合截面缆索可同时结合两种材料的优点，是缆索形式一个新的发展方向，其截面形式、受力和防腐性能有待探索和研究。本申请拟通过理论、仿真分析和模型试验，研究具有良好防腐和受力性能的钢-CFRP组合缆索截面形式。首先研究钢和CFRP的面积比例对悬索桥静动力刚度和跨越能力的影响，确定优化目标比例，并初步拟定以防腐为目的的钢-CFRP组合缆索截面形式。其次，结合理论和仿真分析研究该组合截面在拉、弯、扭等受力模式的单独和耦合作用下的力学行为，进一步优化截面组合形式，并开展在酸、碱、盐、干湿、拉应力等各不利因素单独作用和其中几种不利因素的耦合作用下的加速腐蚀试验。最后，总结组合截面缆索在最不利受力模式下的力学行为特点和最不利腐蚀条件下的防腐设计要点，并考虑尺寸效应等诸多因素，提出钢-CFRP组合缆索截面优化设计理论。研究成果对解决悬索桥主缆腐蚀和跨越能力受限等问题有重大意义。

本项目因现役悬索桥全钢丝主缆存在严重锈蚀而立项，旨在通过本项目研究寻求一种兼具良好防腐和受力性能的钢-CFRP组合截面主缆形式。研究内容主要包含：（1）悬索桥组合截面主缆形式；（2）组合截面主缆防腐性能；（3）组合截面主缆受力性能；（4）组合缆索截面优化设计理论。本项目首先通过整理分析国内外实测和实验结果，得到全钢丝主缆内部腐蚀环境以及现役全钢丝主缆的内部腐蚀特点。再通过理论公式分析了组合截面主缆中钢和CFRP面积比例对悬索桥跨越能力和静动力刚度的影响。综合考虑悬索桥主缆的施工架设、锚固性能、组合截面材料性能差异，以及全钢丝主缆腐蚀特点，拟定的组合截面形式为：圆形主缆截面外围由耐腐蚀的CFRP棒，内部由高强钢丝径向对称构成。然后，分别研究了高强钢丝的腐蚀速率随温度、湿度、拉应力、盐溶液浓度之间的关系，研究表明：钢丝腐蚀速率随温度升高、湿度和拉应力增大、盐溶液浓度升高而加快，多因素耦合作用下加速更加显著。为研究组合截面的防腐特性，分别针对全钢丝截面试件和钢-CFRP组合截面试件进行了一系列的实验室多因素耦合作用的加速腐蚀实验。实验结果表明：与全钢丝截面试件相比，组合截面可降低主缆的整体腐蚀水平，但因CFRP与钢之间存在电位差，且因外围CFRP耐腐蚀，不会产生有助于阻止水汽进入内部的腐蚀产物，宜在外层CFRP与内部钢丝之间设置耐腐蚀绝缘性能好的高分子材料，进行隔绝，可以进一步提高组合截面主缆的防腐性能。基于接触-摩擦理论建立了组合截面主缆的有限元模型，分别分析了组合截面主缆在轴向拉力作用和复杂受力模式下的力学行为。分析结果表明：采用高弹模的CFRP可使组合截面中CFRP承担较多荷载，充分发挥CFRP的高强特点，降低内部钢丝应力。在吊索力作用下，组合截面主缆中各丝受力规律基本一致，安全系数差异较小，组合截面主缆受力性能良好。最后，将本课题的研究成果进行总结，得到钢-CFRP组合截面主缆优化设理论。本文的研究成果有利于提高悬索桥主缆的使用寿命，具有较高的工程意义和经济价值。