Validation of refined numerical modeling for existing RC buildings: comparison between predicted and observed earthquake damage

A reliable estimation of the seismic performances of existing reinforced concrete building is of paramount importance to design proper retrofit solutions. Number of refined numerical models are nowadays available, nevertheless predicting the seismic performance and the earthquake damage at component level is still a challenging task. Marked nonlinear phenomena, strength and stiffness degradation and pinching affect the cyclic behavior of structural members designed with reinforcement details non-conforming with current seismic codes. This, along with the interaction between the bare frame and the stiff infills, makes complex the reproduction of the global structural behavior. This study focuses on a refined modeling procedure properly developed for existing RC frames. The modeling assumptions, the hysteresis assigned to the different building components and the modeling strategy accounting for the infill contribution are presented and discussed. The model validation at component and building level related to case-study buildings damaged by the L’Aquila (2009) earthquake is presented. A component-by-component comparison between predicted and observed damage is shown. The proposed numerical model and the in-depth discussion on the earthquake damage are useful to identify the building weaknesses, estimate the repair costs and design proper retrofit solutions.