Displacement-based seismic design and analysis of different configurations of RC frames

The object of this paper is the evaluation of the seismic response of reinforced concrete frames designed according to the Direct Displacement-Based Design (DDBD) approach. The design was carried out following procedures and regulations included in the Model Code recently proposed for the application of this methodology. The displacement-based approach was investigated considering a set of RC frames characterized by nine storeys and different configurations. In particular the following configurations were studied: regular in elevation, characterized by a setback at the upper storeys and irregular in elevation with a soft storey. The methodology was applied together with a simplified procedure based on equilibrium conditions for determining design member forces. The seismic behaviour of the designed frames was studied by performing pushover and non-linear dynamic analyses on the basis of a fibre model of the structures. A group of earthquake records compatible with design displacement spectrum was selected for the non-linear dynamic analyses. The results of analyses were compared with the seismic behaviour expected from design in order to evaluate the effectiveness of the procedure with particular attention to the different examined configurations.