Abstract

Today, there are a large number of masonry arch bridges in service within railway networks. These old infrastructures have been designed for service loads in the past 100 years. Owing to increased service loads, it is essential to investigate the behavior of masonry arch bridges. Several empirical, analytical and numerical studies have been conducted to estimate the residual capacities of masonry arch bridges. The present study aims to employ the extended finite element method (XFEM) to obtain the ultimate capacities of old arch bridges for the first time. By adopting a non-geometric approach in fracture mechanics and defining initial structural defects, XFEM can easily predict the failure and ultimate capacity of a structure by using the crack growth pattern. Thus, the present study made use of two ageing railway arch bridges that are known to be cracked structures to build a three-dimensional XFEM model. The ultimate capacities and safety factors of the bridges are studied by defining several initial defects in different conditions. Finally, using experimental outcomes, the nonlinear finite element method along with the concrete damaged plasticity model are exploited to validate the results. The results indicate that XFEM agrees very well with the other methods. Considering its unique flexibilities, XFEM can be employed effectively and efficiently to analyze ageing cracked masonry arch bridges.

摘要

今天，铁路网内有大量的砖石拱桥在服役。这些旧的基础设施是为过去 100 年的服务负载而设计的。由于服务负荷的增加，研究砌体拱桥的行为是必不可少的。已经进行了一些经验的、分析的和数值的研究来估计砖石拱桥的剩余承载力。本研究旨在首次采用扩展有限元法 (XFEM) 获得旧拱桥的极限承载力。通过在断裂力学中采用非几何方法并定义初始结构缺陷，XFEM 可以使用裂纹扩展模式轻松预测结构的失效和极限能力。因此，本研究利用两座已知为开裂结构的老化铁路拱桥来构建三维 XFEM 模型。通过定义不同条件下的几个初始缺陷来研究桥梁的极限承载力和安全系数。最后，利用实验结果，利用非线性有限元法和混凝土损伤塑性模型来验证结果。结果表明 XFEM 与其他方法非常吻合。考虑到其独特的灵活性，XFEM 可以有效且高效地用于分析老化开裂的砌体拱桥。利用实验结果，利用非线性有限元法和混凝土损伤塑性模型来验证结果。结果表明 XFEM 与其他方法非常吻合。考虑到其独特的灵活性，XFEM 可以有效且高效地用于分析老化开裂的砌体拱桥。利用实验结果，利用非线性有限元法和混凝土损伤塑性模型来验证结果。结果表明 XFEM 与其他方法非常吻合。考虑到其独特的灵活性，XFEM 可以有效且高效地用于分析老化开裂的砌体拱桥。