SEISMIC VULNERABILITY OF TRADITIONAL BUILDINGS: THE EFFECT OF ROOF-MASONRY WALLS INTERACTION

The seismic improvement of the monumental heritage is of particular relevance in European countries and in Italy in particular, where a large number of ancient masonry palaces and churches have to be preserved from seismic damage. Research has been very active in this field for many years and has provided interesting analysis tools; among these, the recognition of typical damage patterns has proven very efficient for damage assessment and vulnerability analyses. In the specific case of churches, a number of collapse mechanisms has been codified and has become a standard reference. Here attention is focused on a specific mechanism involving the transversal response of the church longitudinal walls and the roof system, which has been associated to frequent cases of severe damage in recent Italian earthquakes. The proposed analytical interpretation of the mechanism permits to highlight the effect of the basic parameters on the general structural response through consideration of the limit equilibrium condition. The procedure is, then, applied to typical example cases, leading to the evaluation of the collapse acceleration. The proposed criterion is suitable for pointing out critical situations simply from visual inspection and basic measurements and may be effectively applied in vulnerability analyses.