Un índice de daño sísmico objetivo para la evaluación de los edificios de hormigón armado

An objective seismic damage index to evaluate the reinforced concrete buildings performance

In modern seismic resistant design codes is considered that the structural elements (columns and beams) have a nonlinear behaviour during the action of an earthquake similar to the considered in design process. This implies that these elements are damaged and it is very interesting for the designer to be able to estimate the expected global damage in the structure and to relate it to the design ductility, and also with the ductility demand. The damage index calculated applying finite elements method, have values that do not reflect the deterioration in the case of buildings designed for low ductility, this feature is contrary with the damage index calculated for ductile buildings. Therefore, in this work an objective damage index is proposed, based on the ductility and the values of the elastic and ultimate stiffness, that is independent of the selected structural typology. The procedure is illustrated by means of the assessment of the index from damage to three buildings, two of which have been designed for low ductility (building with waffle slabs and framed building with flat beams) and a third one that is framed building with depth beams, designed for high ductility. For the three buildings the static nonlinear response has been determined by means of a force-based procedure, and also the performance point corresponding to the three buildings are calculated applying the N2 method. The results obtained demonstrate that the objective damage index proposed provides values that characterize suitably the damage suffered by the three buildings, at the instant of collapse.