Analysis of masonry arch bridges using multi-scale discontinuity layout optimization

Abstract

Masonry arch bridges are still in active usage in many countries across the globe. However, the analysis tools that generally underpin the assessment process for these structures have traditionally been 2D, which means that 3D modes of response cannot be captured. This contribution introduces a multi-scale limit analysis method for 3D masonry arch bridges using discontinuity layout optimization (DLO), which is a highly efficient limit analysis technique that automatically identifies the collapse load and associated failure mechanism of a solid or structure. Using this approach, a macroscopic shell continuum is assumed, using a homogenized material that is obtained by analysing the microscopic behaviour of a representative pattern of masonry units in the structure. Therefore, potential 3D failure modes for masonry arch bridges can be revealed. The basic model assumes rigid masonry units, and takes into account key engineering features such as aspect ratio of masonry units. Simple examples are used to validate the proposed method; then simple square and skew masonry arch bridges are analysed to demonstrate the efficacy of the proposed method.