Safety evaluation of a masonry arch bridge by nonlinear finite element simulations

Using the example of a railway bridge, a procedure for the safety evaluation of existing masonry arch bridges is presented. The investigated bridge was to be preserved and utilized under increased usage requirements. A conventional framework based analysis was not considered to be a promising approach for this particular problem. By nonlinear finite element simulations, however, it was possible to reveal an additional load-carrying capacity. In order to simulate the mechanical behavior of the structure as realistic as possible, the adjacent soil was incorporated in the finite element model. Nonlinear material laws were used for both masonry and soil. For the masonry, the smeared crack approach of nonlinear fracture mechanics has been adopted. The curved bridge axis, lateral loads, and eccentricities of the vertical loads required a 3D modeling. The simulation results allowed to prove structural safety even under exceptional traffic loads anticipated for the future. In addition, possible causes for the existing damage pattern could be identified.