中文摘要：

介绍了二次预应力组合梁的构思、基本原理与特点，阐述了二次预应力组合梁的受力性能、变形性能、结合面徐变应力重分布的研究进展，对二次预应力组合梁在公路桥梁中的应用研究进行了总结分析。指出二次预应力组合梁可以减小预应力混凝土梁的徐变上拱50％以上，从根本上解决减小梁的徐变上拱和提高截面抗裂安全性的矛盾，同时，还可以节约预应力筋10％以上，在公路超薄梁桥、城市立交桥中综合技术经济优势明显；二次预应力组合梁的设计方法、结合面连接方式与构造、结合面抗剪性能、施工技术是进一步研究需要重点解决的问题。

英文摘要：

The concept, basic principle and characteristics of twice prestressed composite beam are introduced, and the mechanical performance, deformation performance and creep stress re-distribution of interface of twice prestressed composite beam are expounded. Then, the researches of application of twice prestressed composite beam in highway bridge are summarized and analyzed. It is concluded that （ 1 ） the twice prestressed composite beam can decrease creep camber of prestressed concrete beam more than 50%, thus, the contradiction between reducing creep camber and improving the safety of section crack resistance can be well solved; （2） twice prestressed composite beam can save approximately 10% of prestress tendons, and has comprehensive technical and economic advantages in uhra-thin beam highway bridges and urban overpass bridges. The further research of twice prestressed composite beam will be focused on the design method, connection mode, structure and shear performance of the interface, and the construction technology.