Reliability of Timber Framed Constructions in Seismic Prone Areas in the Practice Codes Issued from 18th to 19th Century

The analysis of a few significant events of the modern and contemporary history, carried out examining not only the characteristics of the catastrophes but the phases following the occurrence, concerns the earthquakes of Guatemala (1541), Lisbon (1755), Calabria (1783), Lefkas (1826), Casamicciola (1883) and others. Apart from the concern for the humanitarian assistance to injured people, the tax exemption for a certain period, the indications of sanitarian policy in an emergency situation etc., that is a common factor of reports, rules or codes, it is to be noticed that only in a very restricted number of cases technical indications or rules are given for the construction/reconstruction in order to prevent or at least reduce the risk and the amount of damage caused on the buildings by seismic activity. The survey and analysis of the construction practice “codes” presently known, generally issued in seismic prone areas shortly after important earthquakes from the 18th century on, or the reconstruction really put into practice allow to perceive the evolution of the research concerning the origin of the seismic phenomena, the filing, classification, evaluation, interpretation of the damage as well as the slow evolution of the strategies of damage prevention and failure repair. The use and the role, documented since prehistoric times, of the reinforcement of the masonry bearing walls with timber elements or frames is documented in all the seismic zones of the Mediterranean basin, in the widest meaning of the term, as well as all over the world without any apparent mutual influence; then the recommendations, common to some national codes, to make new constructions adopting this building system, is to be regarded as a reference to the traditional practice that had proved to be efficacious at least in preserving the constructions from total collapse and reducing the loss of human lives. The concern for the conservation of the historic buildings, conflicting with the supposed necessity of demolishing the buildings that had been severely damaged, and the rules for the correct repair intervention are only dealt with in the contemporary codes.