Traditional techniques on masonry buildings that improve performance under seismic risk

Some regions of mainland Portugal, especially the southern region, are exposed to considerable seismic hazard. There is also a wide variety of building typologies, including structures of masonry and wood, masonry and reinforced concrete and reinforced concrete built in different times and with different degrees of seismic vulnerability. In the last few years, there was a significant growth in the number of building rehabilitation projects in historic centres of Portuguese cities. Some of these interventions are founded on well-conceived projects which take into account the date of construction and the original construction methods and materials, however, there are somewhat legal procedures which seriously undermine the safety of renovated buildings decreasing their seismic performance. This paper illustrates some provisions on traditional building techniques that ensure a better performance of buildings during an earthquake. It also points out and illustrates some of the major mistakes in building rehabilitation that contribute to increase their seismic vulnerability.