Historical quakeproof building systems in Italy: constructional skill and normative experimentation. Notes for a critical comparison

Italian Building heritage shows a vulnerability of striking topical interest after the last earthquake in Central Italy. To every historical observation of building seismic vulnerability it mostly corresponds an intense search of more effective quakeproof criteria, and of new standards to attenuate the risk. Much less energy is historically devoted to investigating whether the collapse is to be attributed to noncompliant and faulty construction or whether the real full requirement compliance validated the regulatory criteria at that time in force. The introduction of normative discontinuities was preferred instead of continuously verifying historical constructive skills. The study of wood frame-based systems is of great interest: particularly important are the so-called beneventan “case baraccate” (1627) or the “case baraccate” of the Bourbon period (1783): the latter proved a really favorable behavior in the Messina quake (1908). But the general drive to use reinforced concrete systems and the economic pulses leaded to the substitution of “casa baraccata” with reinforced concrete housings, despite the quake collapsed some such buildings. Political and regulatory wills with economic lobbies appear to overcome constructive factors, favoring techniques easily modelled, rather than retaining local skills that proved to translate in effective, sustainable techniques linked to the historical local memory.