钢筋混凝土拱桥基于能力设计原理的抗震设计方法研究

Reinforced concrete arch bridges have been widely used in mountain areas of our country, but the seismic design approach for them is quite limited. To introduce the capacity design principle in the seismic design of reinforced concrete arch bridges, this project takes the most commonly used reinforced concrete deck arch bridges with box sections as the focus to study the seismic performance of reinforced concrete arch bridges and their structural members through both experimental and analytical investigations. First, a suitable flexural yield mechanism is established through nonlinear finite element analysis, which is driven by minimizing the rotation demand in the plastic hinges and overall lateral displacements. After that, quasi-static experimental testing is conducted on the arch units to evaluate their seismic performance and the hysteretic behavior is predicted using a fiber-based model to reveal the ductile mechanism of reinforced concrete arch bridges through a detailed parametric analysis. Finally, ductile members and capacity protected members for the reinforced concrete arch bridges are determined based on the capacity design principle and the ductile seismic design approach is established for reinforced concrete arch bridges. Then, the applicability of this approach is validated through a case study. This project will break through the limitations of the existing seismic design approach for reinforced concrete arch bridges and it is great theoretical significance and engineering value to improve the safety of reinforced concrete arch bridges when subjected to earthquakes events.

钢筋混凝土拱桥在我国山区广泛应用，但其抗震设计方法尚不完善。为了在钢筋混凝土拱桥抗震设计中引入能力设计原理，本项目以广泛应用的上承式钢筋混凝土箱形拱桥为研究对象，采用模型试验和数值模拟相结合的研究方法，对拱桥结构体系及其构件的抗震性能进行系统研究。首先，通过全桥非线性有限元分析，遵循最大可能降低塑性铰弯曲需求和减小全桥位移的原则，建立拱桥结构体系合理的屈服机制。然后，通过对主要受力构件拱圈开展模型拟静力加载试验，系统评估拱圈的抗震性能。进而采用纤维模型对拱圈的滞回性能进行数值模拟，通过大量的参数分析揭示拱圈的延性抗震机理。最后，基于能力设计原理，确定拱桥结构体系中的延性构件和能力保护构件，建立钢筋混凝土拱桥延性抗震设计方法，并以某工程实例验证方法的适用性。项目研究将突破现有钢筋混凝土拱桥抗震设计的局限性，对提高钢筋混凝土拱桥的抗震安全性，具有重要理论意义和工程价值。

拱桥因其受力性能好、跨越能力强、造型美观以及经济适用等优势在世界范围内被广泛应用。随着拱桥施工技术的发展以及混凝土材料强度的提高，混凝土拱桥在大跨度桥梁中竞争优势显著提高，在地质条件良好的地区得以大量修建。然而，现阶段混凝土拱桥仍遵循弹性抗震设计方法，无法满足结构的安全要求。为了在拱桥抗震设计中引入能力设计原理，本项目首先通过非线性有限元软件对钢筋混凝土箱型拱桥开展全桥分析，综合分析各控制截面的内力响应和位移响应发现，拱上立柱作为延性构件可以最大程度地减小塑性铰的弯曲需求和全桥位移。然后以拱桥结构中的主要受力构件拱圈作为研究对象，对其在高轴压比作用下的抗震性能开展了系统的试验研究和理论分析。研究发现试件塑性铰区的抗震性能受轴压比影响显著。随着轴压比的增大，试件延性显著降低，但在高轴压比作用下仍可表现出一定的延性；受弯受剪承载力提高；耗能能力降低，但在高轴压比作用下试件的等效粘滞阻尼比仍满足规范要求；塑性铰区箍筋响应增大，更易屈服。最后，基于能力设计原理，形成钢筋混凝土箱形拱桥抗震分析和抗震设计的指导方针并给出选定的屈服机制延性发展所需的构造细节建议。