The Performance of Two Unreinforced Masonry Churches in Greece Under Gravitation and Earthquake Actions

Abstract

The seismic performance of "Greek" churches made by low-strength unreinforced masonry is examined. These structures were damaged during recent strong seismic activity in Greece combined with long term effects from foundation settlement. Measurements from shear-sliding laboratory tests of stone masonry triplets are presented and discussed together with corresponding numerical simulation results in an effort to quantify the in-plane sliding shear failure criterion. The cohesive surface interaction constitutive law was employed in forming realistic limit-state criteria for such weak mortar stone masonry. Next, the performance of specific "Greek" churches is numerically simulated employing simplified dynamic linear elastic analysis and assumed limit-state criteria. This simplified approach yielded realistic predictions of the observed performance. However, the necessity to obtain a comprehensive set of measured strength properties for such type of masonry construction is 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 stress demands at critical regions. This conclusion is also in agreement with the observed damage.