Abstract
This paper deals with multi-story buildings erected mostly in interwar period in seismic areas and designed for gravitational actions only. The typical structural system is reinforced concrete frames and masonry infills. A usual multi-story interwar structure was chosen in order to evaluate its seismic resilience. There were made in situ measurements for its dynamic characteristics. The numerical model was calibrated according to in situ measurements. There were proposed two methods of increasing the seismic resilience. First method consists in improving the resilience by reshaping without reinforcing. The second method is additional to the first. It consists in reinforcing infilled frames in order to take over seismic loads.