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Unreinforced stone masonry made of low strength mortar has been used for centuries in forming old type stone masonry churches of the “Basilica” typology. 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. A simplified numerical process is presented for evaluating the performance of such damaged stone masonry structures, making use of linear and non-linear numerical tools and assumed limit-state failure criteria. In order to obtain a quantification of the in-plane sliding shear failure criterion, a number of stone masonry wallets were built with weak mortar and were tested in the laboratory. Through the comparison of the obtained numerical predictions with the observed structural behaviour for selected cases of stone masonry “Basilica” churches, the validity of the applied simplified numerical process is demonstrated. It is shown that reasonable approximation of the observed performance of such structures can be obtained when the assumed failure criteria are realistic.

Abstract

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This paper summarizes observations and conclusions from a series of investigations on the seismic performance of stone masonry Christian basilica churches. A considerable number of these churches develops structural damage to the masonry walls-piers that arises from the amplitude of the gravitational and seismic actions combined with the deformability of the foundation. This traditional "old-type" construction for Christian churches still exists in several regions of the Mediterranean Basin, apart from Greece, despite the considerable seismic hazard that these regions are exposed to. An expert system was developed, which utilizes the basic geometric and material characteristics of a given masonry pier together with the in-plane stress resultant demands in a cross section, such as the axial force (Ny) the bending moment (M y ) and the shear force (Q y ), in order to check the performance of such a pier. This is done by comparing the demands posed by these stress resultants with the corresponding capacities as they are predicted by the provisions of Euro-code 6 or from relevant empirical formulae. This is done by considering either the in-plane flexural or the in-plane shear capacity. This expert system is applied to typical basilica churches damaged by the recent 2014 Kefalonia earthquake in order to demonstrate its usefulness in the evaluation process of either the expected or the observed earthquake performance of this type of heritage structure.