高性能装配式组合桥墩-基础接头抗震性能与设计准则研究

Pier-foundation joints are the key parts of prefabricated piers, which control the performance and safety of the structure. It is an important technical way to improve the seismic performance of the assembled composite piers in the strong earthquake zone by improving the material properties and joints structure. This project introduces high-performance steel and ultra-high-performance fiber concrete into the joint to form a high-performance assembled composite pier-foundation joint. By means of model test, numerical simulation and theoretical analysis, the force transmission mechanism and energy dissipation capacity of three different joints are studied. By analyzing the influence laws of high material and constitution on the ductile performance, the reasonable matching of materials and constitutions in the joint are explored, as well as the rational constitutions. The structural design criteria of high-performance assembled composite pier-foundation joints are established. The main factors affecting the ductility of joints are also identified, and the simplified calculation model of ductility of bridge piers is established. On the basis of test, numerical simulation and theoretical analysis, the ductility design criteria of high-performance assembled composite piers are constructed. The research results of this project can provide a scientific basis for the design and construction of high-performance assembled composite piers in China, which is of great significance for promoting the industrial construction and green development of bridges.

桥墩-基础连接接头是装配式组合桥墩中的关键受力部位，控制着结构整体性能与使用安全，通过改善材料性能和接头构造是提升强震区装配式组合桥墩抗震性能的重要技术途径。本项目将高性能钢、超高韧性纤维混凝土引入到接头中，形成高性能装配式组合桥墩-基础接头，针对螺栓锚固式、预应力式和埋入式等典型接头形式，采用模型试验、数值模拟和理论分析相结合的方法，探究接头的传力机制与耗能能力，分析高性能材料及构造型式对接头和结构延性性能的影响，探寻材料与构造的合理匹配，提出接头的合理构造，建立高性能装配式组合桥墩-基础接头的构造设计准则；明确影响接头延性性能的主要因素，建立桥墩的延性简化计算模型，构建高性能装配式组合桥墩的延性设计准则。本项目研究成果可为我国高性能装配式组合桥墩的设计、施工提供科学依据，对推动桥梁工业化建造和绿色发展具有重要意义。

装配式钢-混凝土组合桥墩结合了钢桥墩与混凝土桥墩的优点，为装配式下部结构在强震区应用提供了新的型式。为进一步提升装配式组合桥墩的抗震性能，本项目将高性能钢（HPS）与超高性能水泥基复合材料（UHPFRC）应用于组合桥墩中，形成高性能装配式组合桥墩，对其关键部位—桥墩-基础接头的抗震性能与设计准则开展研究，提出了高性能装配式组合桥墩-基础直接埋入式、PBL埋入式和半埋入式接头，研究了接头形式及构造、截面构造、埋入深度、材料选用等关键参数对接头破坏模态、承载力、延性及耗能能力等的影响规律，明确了不同类型接头的传力机制，提出了接头的合理构造形式，建立了高性能装配式组合桥墩-基础接头的承载力计算方法，构建了高性能装配式组合桥墩-基础接头设计准则。研究结果表明，对于埋入式接头，管内与接头后浇筑部分采用UHPFRC，增加PBL剪力键、减小PBL间距以及增加PBL开孔直径等构造措施均可以改善埋入式接头的抗震性能；提出了直接埋入式与PBL埋入式组合桥墩的埋深建议值；钢管强度对结构抗震性能的影响相对较大，厚度次之，空心率最小；轴压比大于0.3后，随着轴压比的增加，结构抗震性能降低程度相对较大；对于半埋入式接头，相同埋深下，半埋入式接头的水平极限承载力、延性较直接埋入式接头有一定提高；而桥墩埋深降低、螺栓数目和直径减小，结构的破坏模式会发生改变，抗震性能降低；结合韧性抗震设计理念，提出了高性能装配式组合桥墩-基础接头的韧性抗震设计方法，建立了抗震设计流程，构建了高性能装配式组合桥墩-基础接头的设计准则。本项目研究成果可为高性能装配式组合桥墩的设计建造和推广应用提供技术支撑，推动桥梁工业化建设和绿色低碳发展。