Parametric study of masonry shells form-found for seismic loading

In this paper, a form finding approach is presented that allows for the shape generation of masonry shells in seismic areas. Through a parametric study, this method is illustrated for a wide variety of boundary conditions and leads to a set of shapes for double layer thin shells. Earlier studies have shown that continuous shells behave well during earthquakes due to their high stiffness and low mass. Additionally, there is a renewed interest in constructing masonry shells because of their low carbon impact, spurring the need to understand how such shells should be designed in seismic areas. Currently available form finding techniques for shells, however, rely solely on gravity loads for the generation of their shape and do not account for seismic loading The form finding approach examined here is based on the generally accepted assumption that masonry structures cannot resist tensile stresses. Therefore, for masonry shells subjected to both vertical gravity and horizontal seismic loading, a compression-only load path (in 2D often referred to as a thrust line) should be present within the thickness of the shell to avoid collapse mechanisms. Through the application of an inversed hanging chain model subjected to lateral loading in a dynamic relaxation solver, shell forms are generated for which it can be ensured that such a load path exists To illustrate this methodology, a variety of shapes are generated based on a set of parameters including boundary conditions and net stiffness. The shapes discussed in this paper are the first instances of compressiononly shells reported in literature, whose forms are successful and efficient in withstanding combined gravity/seismic loading. This paper's findings demonstrate how to tailor masonry shells for a resilient built environment and can be extended to the shape generation of shells constructed out of other compression-only materials such as unreinforced concrete, stone and earth.