Vulnerability of reinforced-concrete-frame buildings and their occupants in the 2009 L'Aquila, Italy, earthquake

Reinforced-concrete-frame buildings, particularly midrise multifamily condominium structures, experienced significant damage in the 2009 L'Aquila, Italy earthquake. The most frequently observed damage was cracking and failure of nonstructural masonry infill walls, but some buildings also experienced structural damage, including column shear failure and collapse. Fieldwork conducted approximately 3 weeks after the earthquake was used to collect data from approximately 483 concrete frame structures in L'Aquila, including building location, characteristics, damage, and postearthquake occupancy. A second survey 1 year later investigated whether buildings had been repaired or reoccupied. These results show that the building damage is correlated to height, usage, elevation irregularities in strength and stiffness, and the ground-shaking intensity at each site. This information provides the basis for empirically derived fragility functions for this typology of concrete frame. Approximately 0.2% of concrete structures collapsed. The study also shows that occupants of tall and older condominium structures in areas north and west of the city center were particularly affected; single-family homes were less damaged and more likely to be occupied during fieldwork. Damaged concrete buildings have led to significant disruption of the community and social fabric, causing the temporary or permanent closure of small businesses, medical offices, restaurants, churches, and schools.