Numerical investigation of the influence of earthquake forces and foundation settlement on the performance of Post-Byzantine churches

Abstract

The earthquake performance of stone masonry Post-Byzantine churches subjected to seismic forces is examined. First, a three-nave Basilica is studied with a system of stone-masonry vaults and domes as a superstructure together with a wooden roof. Next, a cruciform type 18th century church is studied which also utilizes a system of cylindrical vaults and spherical domes that form the superstructure together with the wooden roof. In addition, a three-nave 18th century Basilica is examined where the wooden roof is supported directly on the peripheral masonry walls and the internal colonnades. All these churches developed structural damage to the masonry that is believed to arise from the amplitude of the gravitational and seismic actions combined with the deformability of the foundation, which is examined here. It is shown that the foundation deformability explains, partly, the appearance of structural damage. The numerically predicted regions that reach limit state conditions correlate well with actual damage patterns. Moreover, the vaults and domes of the superstructure appear to be vulnerable also.

Dynamic Behaviour and Earthquake Performance of Greek Basilica Churches With Foundation Deformability

“…Ratio values smaller than one (Rσ, Rτ ,R M <1) predict a corresponding limit state condition ( [9], [10, [11], [12], [15]). Figures 5a and 5b depict Rσ ratio values for the masonry arches above the internal colonnades.…”

“…This is based: a) On the numerical predictions of the state of stress of the masonry walls as obtained from the dynamic analysis of this elastic numerical simulation being subjected to a combination of dead load and seismic forces and b) On the values of the strength over demand ratios at the most critical locations of the masonry walls and vaults. In doing so, strength values were assumed for in-plane shear and flexure as well as out-of-plane flexure for relatively weak unreinforced stone masonry ( [9], [10], [11], [12]). …”

“…The numerical investigation of this church included the following ( [9], [10], 11]): a) Simulation of the behaviour assuming non-deformable supports at the foundation level. b) Simulation of the behaviour assuming deformable supports at the foundation level, introducing at this level elastic springs with properties reflecting the actual soil deformability that was found from in-situ sampling.…”

“…In some instances, the deformability of the soil caused considerable damage as is the case of the church of The Assumption of the Virgin Mary at Dilofo-Voio-Kozani, as will be presented in section 2 ( [7], [8]). In some other cases the main cause of recent damage is the earthquake activity that is accentuated by the deformability of the soil ( [9], [10], [11], [12]). This is presented in the section 3, where the damage of the church of Agia Triada at Vithos-Kozani and of Profitis Elias at Siatista-Kozani is also included, as well as in section 4 where the earthquake performance of the old Byzantine church of Achiropoiitos in Thesalloniki is examined.…”