ON THE ROLE OF ROAD NETWORKS IN REDUCING HUMAN LOSSES AFTER EARTHQUAKES

A road-network reliability analysis for a scenario seismic event is performed for a region of southern Italy characterised by a large number of small to medium municipalities quite close to each other and served by a dense network of roads. Among the many functions of the road network, whose links may fail after an earthquake due to the collapse of the bridges within them, the one selected for the present study is that of allowing rescue operations to be carried out at the sites of collapsed schools. For this to be possible, connection must be maintained between schools that survived, rescue centres and hospitals. Required elements for the study are the fragility curves of the bridges, the schools, the hospitals and the rescue centres. Output of the study is the expected value of the fraction of the total population in the area that is in need of assistance and cannot be hospitalised due to either failure of the network or other vulnerable components.     

SEISMIC RISK ASSESSMENT OF RC STRUCTURES WITH THE “2000 SAC/FEMA” METHOD

The applicability of a new, fully probabilistic approach to seismic design and assessment of reinforced concrete (RC) structures is investigated. Fundamental advantages of the method are mathematical simplicity and comparatively light computational effort. The original formulation, which was developed for steel structures, is first illustrated; ah extension which allows consideration of multiple failure mechanisms, typical of RC structures, is then proposed. The applicability of the method is demonstrated through an example: the seismic risk of a four storey RC building that was not designed for seismic resistance is evaluated. Three failure mechanisms are considered: joint failure, column shear failure and drift failure.