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 concretebuilding is of paramount importance to design proper retrofit solutions. Number of refinednumerical models are nowadays available, nevertheless predicting the seismic performanceand the earthquake damage at component level is still a challenging task. Marked nonlinearphenomena, strength and stiffness degradation and pinching affect the cyclic behavior ofstructural members designed with reinforcement details non-conforming with current seismiccodes. This, along with the interaction between the bare frame and the stiff infills, makescomplex the reproduction of the global structural behavior. This study focuses on a refinedmodeling procedure properly developed for existing RC frames. The modeling assumptions,the hysteresis assigned to the different building components and the modeling strategy accountingfor the infill contribution are presented and discussed. The model validation at componentand building level related to case-study buildings damaged by the L’Aquila (2009)earthquake is presented. A component-by-component comparison between predicted and observeddamage is shown. The proposed numerical model and the in-depth discussion on theearthquake damage are useful to identify the building weaknesses, estimate the repair costsand design proper retrofit solutions.