COLLAPSE MECHANISMS OF MASONRY BUILDINGS DERIVED BY THE DISTINCT ELEMENT METHOD

The present paper investigates the crack patterns and the collapse mechanisms of stone masonry structures subjected to severe earthquake excitations, using a distinct element representation of the structural walls. The investigation was focused on typical structures of traditional Cypriot architecture. It was found that, for typical houses, the most common mode of collapse is the out-of-plane failure of the façade walls, while other failure mechanisms were related to the excessive shearing of the stiffer walls and the collapse of window or door lintels. For this reason, three-dimensional analysis is usually necessary, in order to capture the response realistically. However, the response of the vaults and arches can be estimated quite realistically by two-dimensional modeling. A number of possible intervention techniques were also studied, as the addition of concrete ties or a concrete slab at the roof level and the construction of additional structural walls. Such techniques result in decreasing the out-of-plane deformation of the walls, diminishing, in a great extend, the possibility of collapse. The addition of steel ties to arched walls also enhances the seismic resistance. It is recognized that further research is needed in the field, especially in the simulation of the progressive damage and degradation of the masonry fabric during subsequent shaking cycles