Comparison between two historical timber framed solutions representing both tradition and pre-modern earthquake resistance concepts

The consciousness of the need to resist seismic actions has been present in the building tradition for long, well before the scientific approach to the problem was started and earthquake engineering methods were introduced. Since the beginning, earthquake-proof solutions have been developed empirically, learning from the behaviour of buildings, as highlighted by post- earthquake damage surveys. The need to develop strategies to resist earthquakes is a constant problem and, since ancient times, learning from the past has been a good way to improve the quality of buildings. Remarkable cases of refined solutions are offered by the traditional building system which is still in use in Lefkada, one of the Greek islands in the Ionian sea and by the so called “Borbone system” in Southern Italy. These examples refer to construction systems which were constantly improved after each earthquake and are still effective, also offering interesting suggestions for new design. Both systems are based on the wood traditional architecture developed in the geographical areas to which they belong. The sophistication level they reached deserves special consideration, as it represents the best of the seismic design criteria in use in the 18th and 19th centuries, also anticipating some leading concepts present in modern codes. Examples of this are given by the interlocking of orthogonal walls as the premise to the box behaviour, regularity in plan and elevation, the reduction of dead loads. This work proposes a comparison of the two earthquake resistant systems, emphasizing the most meaningful aspects of the Lefkada and Borbone technologies, which are clearly in line with modern seismic design concepts. These aspects deserve special attention, as they might provide inspiration for new constructive strategies which, in line with the current sustainability requirements, would result both effective and environment compatible.