Resistenza sismica di telai in c.a. progettati con il Regio Decreto 2239/1939

Reinforced Concrete buildings currently represent over 50% of the total building stock in Italy. Many of them, designed before the advent of seismic codes, were constructed in the period ’50s-‘70s, showing peculiar structural characteristics and material qualities. In the paper the seismic resistance of some plane frames representative of mid-rise building types designed to vertical loads and constructed in the period pre-70s, has been evaluated. Based on a purposely set up methodology, a simulated design of the structures has been made with reference to the codes in force, the available handbooks and the current practice at the time of construction. The seismic response is calculated through non linear dynamic analyses using natural accelerograms relevant to Italian earthquakes. The seismic behaviour has been analysed emphasizing the role of infills and, particularly, of the building age through a comparison with the results of previous studies on post-70s structures.