基于力学与造价的CFRP-钢组合拉索斜拉桥设计理论

针对1400～2800m主跨斜拉桥整体刚度不足的问题，提出一种新型结构方案——碳纤维增强塑料（CFRP）-钢组合拉索斜拉桥。该方案将CFRP斜拉索与传统钢斜拉索同时应用于斜拉桥中，组合2种材料高强轻质及弹性模量高的优点，以：达．到提高斜拉桥整体刚度的设计目的。通过基于力学与造价的参数分析提出该组合拉索斜拉桥的3种设计原则：等安全系数等效刚度最优、等安全系数等效刚度性价比最优、等造价等效刚度最优，并分别给出详细的设计步骤及设计用图。最后，进行了多种方案1400m主跨斜拉桥试设计。结果表明：CFRP-钢组合拉索斜拉桥在力学与经济性方面均具有一定优势，其工程应用具有可行性，是主跨为1400～2800m斜拉桥的优选方案之一。

Design of Cable-stayed Bridges with CFRP-steel Composite Stay Cables Based on Mechanical and Economical Behaviors

To solve the problem resulting from the low structural stiffness,authors proposed a new design of cable-stayed bridges with composite carbon fiber reinforced polymer(CFRP)-steel stay cables,especially for the cable-stayed bridges with main spans of 1 400~2 800 m.More specifically,the CFRP stay cables with high strength-to-weight ratio and traditional steel stay cables with high elastic modulus were combined together for application in cable-stayed bridges,which could improve the entire stiffness of bridges.Through a parametric study concerning the equivalent stiffness and economical behavior,three design strategies for the composite cable-stayed bridges were proposed in details: the best equivalent stiffness with equal safety factor,best equivalent stiffness-to-cost ratio with equal safety factor and best equivalent stiffness with equal budget.The design procedure and design chart based on the proposed strategies were also provided.Finally,the feasibility of the proposed cable-stayed bridges was discussed through a case study of a cable-stayed bridge with a main span of 1 400 m.The results indicate that the proposed composite cable-stayed bridges can demonstrate a high equivalent stiffness and can be an excellent selection for the bridges with main spans of 1 400～2 800 m.