Abstract
It is of great importance to assess the seismic risk of existing buildings located in a high seismic region to avoid destructive damages due to severe earthquakes. It is, therefore, necessary to estimate the seismic capacity of structures and strengthen them if required. It is also well recognized, however, that the structural safety may be rarely evaluated with certainty due to uncertainties of ground motion, ultimate strength and ductility of structures, and earthquake response etc, and should be regarded probabilistically rather than deterministically. This paper describes 1) the seismic capacity of buildings damaged due to recent severe earthquakes in Japan, 2) the seismic capacity of existing buildings both before and after strengthening, 3) the relationship between the decision criteria and the seismic capacity of damaged and existing buildings, and 4) applicability of probabilistic approach to estimate the earthquake damage ratio and effects by strengthening.
