Dynamic and earthquake behaviour of Greek post-byzantine churches with foundation deformability - Experimental investigation of stone masonry material properties

Abstract

The dynamic and earthquake behaviour of Post-Byzantine Christian churches made of stone masonry is examined. All these churches developed damage to their masonry elements due to the amplitude of the gravitational and seismic actions combined with the deformability of the foundation. The numerical results together with assumed strength values are utilized to predict the behaviour of the various masonry parts in in-plane, shear, and normal stress as well as out-of-plane flexure. It is shown that the foundation deformability partly explains the appearance of structural damage. When comparing the numerically predicted regions that reach limit state conditions with actual damage patterns a reasonably good agreement in a qualitative sense can be observed. The masonry walls near the foundation, the door and window openings and the roof appear to be the most vulnerable either in out-of-plane bending or in in-plane shear for the critical combination of seismic forces and gravitational loads. The vaults and domes of the superstructure also appear to be vulnerable. The effectiveness of retrofitting schemes is also discussed. A relatively mild retrofitting scheme is examined that utilizes special mortar injections as well as semi-temporary shoring together with wooden and metal ties. The numerical investigation is supplemented with a series of limited laboratory tests on constituent materials which represent old stone masonry.