Seismic retrofit of cultural heritage buildings – when less is more

In 1356, Basel was subjected to an earthquake with an estimated magnitude of 6.6; it is the largest known historical earthquake in central northern Europe. During this earthquake and the fire that followed large parts of Basel were destroyed. Such an event can occur again at any time in the future. To be prepared, it is essential to evaluate the seismic resistance of the existing building stock. The character of the city centre of Basel results largely from its naturally grown fabric of stone masonry buildings from different epochs. Stone masonry buildings belong to the most vulnerable structures under seismic excitation. At the same time, they are part of the Swiss cultural heritage and not only their appearance but also the structure as such should be maintained. This paper reports on a collaborative project between EPFL and the University of Pavia, which aims on the one hand at developing realistic models for the seismic response of stone masonry buildings and on the other hand at developing minimum intervention strategies that are reversible and as little intrusive as possible and therefore suitable for cultural heritage buildings. This paper describes first findings from the various experimental campaigns that are part of the project and explores how stone masonry typologies can be analysed using image analysis procedures.