Serviceability and Damage Scenario in Irregular RC Structures: Post-Earthquake Observations and Modeling Predictions

The catastrophic earthquake that struck the city of L’Aquila in early April 2009 caused extensive damage to buildings at the University of L’Aquila. Among these edifices are those of the Engineering Faculty, which, in particular, suffered large structural displacements and accelerations that resulted in failures of nonstructural elements (infills, false ceilings, door and window frames), the breakage of wiring and piping systems, and the destruction of furniture and machinery. Of these buildings, the so-called Edifice A presents the most critical damage scenario, requiring a significant rehabilitating intervention. The structural behavior of this building, composed of seven independent RC substructures, is the object of intensive investigation; this is in part because irregularities among these substructures, in terms of geometry, stiffness, and weight distribution, provide a rich case study for interpreting different structural and nonstructural damage scenarios. The paper interprets the observed damage through use of incremental analyses for evaluation of the threshold between linear and nonlinear structural behavior. For this purpose, several finite-element (FE) models are developed with increasing complexity in the geometry and the shear-wall modeling. Capacity curves obtained by the nonlinear pushover analyses are afterward compared with the perceived seismic demands of the structures including site effects. Moreover, based on simplified analyses, numerical evaluations of acceleration-producing failures in the infill walls and the split-face brick walls were performed to achieve an overall description of the structural and nonstructural damage.