高强钢丝网增强UHPC加固混凝土桥墩抗震机理与设计方法研究

既有钢筋混凝土桥墩早期设计规范不合理、施工缺陷以及长期使用过程中的损伤、老化是其在地震作用下易于破坏的重要原因，应用UHPC进行外包加固可有效发挥材料在耐久性和断裂韧性方面的优势，但现有抗震加固方式未能充分利用UHPC材料的损伤容限。为此，本项目提出采用UHPC匹配高强钢丝网，对混凝土桥墩塑性铰区域进行预防性抗震加固，力求最大程度提升其抗震性能。本项目主要研究内容包括：（1）通过压弯构件非线性承载力分析理论，优化加固桥墩试件抗震设计参数；（2）开展界面粘结性能试验和拟静力试验，探讨UHPC与混凝土桥墩界面变形协调机制；（3）建立加固桥墩抗震有限元模型，结合拟静力试验研究，揭示高强钢丝网增强UHPC加固混凝土桥墩损伤劣化机理；（4）基于系统的试验研究和数值分析，构建加固桥墩恢复力和塑性铰长度数学模型，提出高强钢丝网增强UHPC加固混凝土桥墩抗震设计方法，为其工程应用提供理论支撑和设计参考。

The reasons such as the unreasonable design code in the early, construction defect, damage and degeneration during the long-term use for the existing reinforced concrete piers, will result in the potential failure of the structures under the earthquake. The superiority of the material on the durability and fracture toughness can occur when the reinforced concrete piers are strengthened by UHPC. However, the existing strengthening modes using UHPC can’t completely develop the damage tolerance of the material. Therefore, a preventative seismic retrofitting of concrete piers using UHPC jackets and high-strength steel wire meshes is proposed in the project for promoting the seismic performance of the concrete piers. The research content is mainly as follows: (1) The capacity analysis of beam and column is carried out to optimize the design parameters of the retrofitted concrete pier specimens; (2) Based on the interface adhesion and cyclic loading tests, the mechanism of interface deformation compatibility between UHPC and concrete pier is discussed; (3) The damage degradation process under the cyclic loading for the concrete piers strengthened by ultra-high performance concrete jackets and high-strength steel wire meshes is estimated, based on the established ductility analysis model and the cyclic loading test; (4) After the systematic experimental study and simulated analysis, the mathematical models including the restoring force and plastic hinge length are established, and the seismic design method of the strengthened pier is put forwards, which will provide the theoretical support and designed reference for the engineering application.