Aspects of Seismic Assessment and Redesign of Traditional Masonry Buildings (original) (raw)
Most of the traditional greek buildings (new-classic ones or not, small or large), with an age of more than 75 up to 250 yrs, are made of rubble stone masonry with a large volume of low strength lime mortars, while their floors/roofs are mainly made of timber. Their seismic assessment and redesign, based on recent conceptions and normative or informative code principles and criteria, is a challenging problem for the Structural Engineer, not to mention restrictions imposed due to the monumental character of almost all of these old buildings. To this end, the new “frame” of Euro-Codes, and especially of EC 6 and EC 8, is applied in general, as recently completed by the new Greek Codes on (Structural) Assessment and Interventions (nGCSI, 2012), fully harmonized with this “frame” of ECs but far beyond them and more detailed, with a lot of relative application rules. Several aspects are involved in structural assessment and redesign of such old buildings, as covered by the Codes and shortly presented/discussed in this paper, such as : Investigation and documentation of the geometrical and the mechanical data of the existing building, together with their reliability levels (DRLs), i.e. the so-called “knowledge levels”, influencing almost all phases and steps of the design; Quantitative assessment and documentation of any wear, deterioration or damage, of any kind, together with a practical but reliable and safe assessment of the residual mechanical characteristics, based on damage levels (DLs); Decision regarding the performance level (PL), i.e. the foreseen or expected degree of damage during the earthquake itself, probably different for the assessment or the redesign of the structural interventions; Aspects of mechanical behaviour of the masonry (and other) elements, out-of-plane and in-plane response, macro-models etc., before and after repair or/and strengthening, as well as Methods of analysis and dimensioning or redimensioning, linear and non-linear, checks in terms of force or of displacement, depending on PLs and based on skeleton curves. In this paper, most of the related issues are shortly covered, as faced during the structural design, while certain characteristic examples and applications are presented.