Design, analysis and construction of hydrostatic masonry bridges: An assessment of load capacity using the discrete element method and physical scale models

Abstract

Masonry is a building technique extensively used throughout history in different applications. However, structures in concrete have become common practice during the last century. Even though masonry bridges cover a large portion of existing bridges, and are a sustainable choice because of their adaptability and long service life, sufficient methods to assess and design masonry bridges are not clear. In this master thesis, the collapse load of masonry bridges designed as hydrostatic shells is investigated. The methods used are hand calculations, load tests on phys ical scale models and computational analysis using the Discrete Element Method (DEM). To validate the computational method an analysis is performed on a simple masonry arch as it is a known case. To validate the computational method, an analysis is performed on a simple masonry arch, a well-documented case, thereby obtaining useful coefficients for the unproven concept of the hydrostatic bridge. The form finding process is done in Rhinoceros3D and Grasshopper, and the geom etry created is used to model both the Discrete Element Model and the physical model. The hand calculations provided highly conservative results, as the resulting collapse load from the DEM analysis is 66 times larger and from the physical load test six times larger. The computational and physical models behave similarly when loaded, and both indicate that the critical loading position is in the midspan of the bridge. The physical model was loaded with 13.9 kg before collapse. By applying dimensional scaling, this result translates to 46.9 tonnes for a full-scale bridge. This indicates that the bridge concept is viable at full-scale. The result from the DEM analysis is qualitatively good but over-estimates the collapse load. Further work includes adding features to the computational model to provide more reliable results and investigating different geometries for the hydrostatic bridge.