Cost-Effective Seismic Isolation Retrofit of Heritage Cathedrals in Haiti

In the past earthquakes, heritage buildings have sustained severe damage and collapse in recent earthquakes, including in Italy (2009), Haiti (2010), and New Zealand (2011). For these buildings, the main vertical and lateral load bearing members are typically use variations of unreinforced masonry stone/rubble walls. These walls have little ductility and are susceptible to in-plane and out-of-plane failures that can result in building collapse. The situation is more pronounced in Haiti for heritage structures due to poor quality of design and workmanship. Heritage buildings were significantly damages in Haiti in past earthquakes (including the 2010 event). A proposed mitigation strategy combining seismic isolation and superstructure intervention was used to upgrade selected cathedrals in Haiti. The proposed method significantly reduces the level of seismic excitation acting on the existing walls and limits the superstructure retrofit, and thus preserves the historical features of the structures. Application of this technique to two cathedrals in Haiti is presented.