大跨径UHPC-波形钢腹板组合箱梁桥新体系扭转与畸变性能研究

波形钢腹板组合箱梁桥采用折叠型钢板替代混凝土腹板，减轻了部分自重并彻底解决了腹板开裂问题，但其顶底板为普通混凝土，依然存在抗拉强度低、徐变偏大等问题，导致结构在受力和耐久性方面存在不足。为此，申请者提出了大跨径UHPC-波形钢腹板组合箱梁桥新体系，即利用UHPC超强的力学性能和耐久性，替换顶底板中常规混凝土，同时增设密集横隔板。新体系具有自重轻、开裂风险低、长期变形小、耐久性好等优势，有望彻底避免大跨箱梁桥开裂和下挠问题。新体系属于典型的薄壁结构，扭转与畸变问题突出，需要重点关注。本项目采用试验、理论与数值仿真相结合的手段，对新体系的扭转与畸变性能开展研究，旨在：掌握偏载下的扭转畸变性能，揭示纯扭作用下的承载机理与破坏特征；建立新体系的扭转与畸变计算理论；提出扭转畸变性能改善措施，给出横隔板间距建议公式。研究成果可进一步拓宽波形钢腹板组合结构体系范畴，具有显著的理论研究意义和工程应用价值。

Composite box girders with corrugated steel webs (CBGCSWs) are developed by using corrugated steel plates to replace concrete webs in traditional concrete box girders. This type of structure possesses many advantages, such as light self-weight and complete avoidance of web cracking. However, the top and bottom slabs of CBGCSWs are made by normal concrete which has low tensile strength and large creep deformation; therefore, CBGCSWs have shortcomings in structural behaviour and durability. To solve this problem, the applicant proposes a new structure system by replacing the normal concrete slabs of CBGCSWs with ultra-high performance concrete (UHPC) slabs. In addition, dense diaphragms are also added to increase stability. The new structure system is called long-span UHPC box girder bridges with corrugated steel webs. The proposed new system possesses lots of advantages including light self-weight, low risk of cracking, small long-term deflection and good durability, and could completely solve the problems of girder cracking and excessive deflection. The wall thicknesses of the proposed new system are relatively thick, which makes the torsion and distortion performance a critical concern. In this project, the torsion and distortion performance of the new system is systematically investigated using model test, theoretical analysis and numerical modelling. The aims of this project are to mastering the torsion and distortion performance of the new system under eccentric loads and revealing the bearing mechanism and failure characteristic under pure torsion; establishing the calculation theory for the torsion and distortion of the new system; developing measures for improving the torsion and distortion performance and proposing the equation for diaphragm spacing. The expected research findings of this project will broader the scope of composite structure with corrugated steel webs. It is of great theoretical significance and social benefit.