This thesis focuses on enhancing the assessment of masonry arch bridges through the application of advanced three-dimensional (3D) continuum finite element modelling (FEM). Many historical bridges in the Netherlands were designed for lighter loads than those imposed by current traffic conditions. Consequently, their structural evaluation is crucial to ensure safety, optimize maintenance strategies, and preserve cultural heritage. Existing design standards codes provide limited guidance for masonry bridge assessment, which emphasizes the need for refined numerical modelling techniques capable of capturing the real mechanical behavior of these complex structures.
To address this gap, a series of three- and two-dimensional finite element models were developed in DIANA FEA, based on a full-scale experimental benchmark bridge tested in the United Kingdom. The modelling approach incorporated both linear and nonlinear material behaviors for masonry and backfill using the total strain crack and Mohr-Coulomb constitutive models, respectively. Interface elements were used to represent the contact and frictional interactions between materials, while soil-structure interaction effects were explicitly modelled. The study systematically examined the influence of spandrel walls and backfill confinement on the bridge’s global stiffness, load distribution, and ultimate capacity.
Model calibration was carried out using the mechanical properties and geometrical parameters provided by the benchmark test. The 3D nonlinear continuum model was validated against experimental results in terms of radial displacements, cracking, and collapse mechanisms. Comparative analyses between the 3D and 2D models demonstrate that the inclusion of spandrel walls in the 3D framework increases initial global stiffness by 30-36 % and peak-load capacity is increased by 50%. The 3D model accurately reproduced the load spreading through the backfill, the development of cracks, and the redistribution of stresses after cracking, but the 2D plane strain model was unable to capture effectively, which underestimated the capacity by 55%.
Overall, the findings confirm that nonlinear 3D continuum finite element modelling provides a more realistic representation of the structural response of masonry arch bridges. This modelling strategy not only improves predictive accuracy but also offers valuable insights for structural assessments. The outcomes of this research contribute to developing reliable evaluation methodologies and serve as a reference framework for future studies and engineering practice in the assessment of masonry arch structures.