UNREINFORCED STONE MASONRY CHURCES IN GREECE UNDER GRAVITATIONAL AND EARTHQUAKE ACTIONS

Unreinforced stone masonry made of low strength mortar has been used for centuries in forming old type stone masonry “Greek” churches. The seismic performance of such stone masonry structures damaged during recent strong seismic activity in Greece combined with long term effects from foundation settlement is presented and discussed. In order to obtain a quantification of the in-plane sliding shear failure criterion a number of stone masonry triplets were built with weak mortar and were tested in the laboratory. Measurements from such shear-sliding tests involving three stone and two mortar joints are presented and discussed together with corresponding numerical simulation results. The cohesive surface interaction constitutive law, with values of its parameters validated through the used process of the specific triplet test, can be also employed in forming realistic limit-state criteria for stone masonry elements. The used simplified dynamic linear elastic analysis can yield realistic prediction of the expected performance of such stone masonry structures. However, the necessity to obtain a more comprehensive set of measured strength properties for such type of masonry construction must be also underlined. From this simplified dynamic linear elastic analysis it can be concluded that the soil-foundation deformability results in a significant increase in the tensile stresses at the region that the tympanum of the spherical dome is supported on the vaulting part that springs from the two interior masonry pilasters and the apse. This conclusion is in agreement with the observed damage that developed in the region of the structural system for this church.