Abstract

Masonry arch bridges form an integral part of the Polish road and railway infrastructure. They are the oldest structure types in the bridge population with thousands still in service despite their age and the significant changes in loading conditions since their construction. The design of these structures was based on empirical rules and contemporary railway and road loads, which has resulted in structures with an inherent ability to withstand greater loads and extreme weathering conditions. Today many masonry arches carry a load that is radically different from that which existed when they were constructed. In order that European roads and railways may accommodate increased axle loads, speeds and a greater volume of freight traffic, it is necessary to assess the load carrying capacity of existing masonry arch bridges. Assessment of masonry arch bridges is difficult as there is little knowledge or experience of the design of these structures to modern standards. In addition, many masonry arches belong to the civil engineering heritage, and their substitution or refurbishment requires careful consideration with maintenance strategies adopted to promote solutions that preserve and restore these structures instead of their replacement. To provide confidence in the assessment result, reliable input parameters for the calculations are required. This paper gives suitable possibilities of the calculations methods for the assessment of the load carrying capacity of existing masonry arch bridges. The masonry criterion, which take its mechanical properties under consideration, are presented. The analysis was performed on the basis of Coulomb strength criterion including isotropy and anisotropy of masonry structure. The application of the limit load theory was discussed as well. The practical issue of vaults stability determination methods are herein introduced. The well-known, but modified, pressure center line method and stability analysis based on destruction mechanism are presented. The use of destruction mechanism was exposed during vault stability finding.