Engineering Structures
José A.Gallardo, Matías F.Chacón
Building collapse, Non-linear finite element model, Continuum concrete model, Shear wall building, Uncertainty analysis
Buildings with Reinforced Concrete (RC) walls are commonly used to resist lateral forces in seismic countries because they provide high lateral stiffness and strength. In recent earthquakes, shear wall buildings have shown good behavior in general; however, a small percentage underwent severe damage localized typically in lower stories. Several numerical models have been developed and proposed to simulate the failure mechanism and behavior of RC walls. From the existing models, only those denoted as micro-models can accurately simulate the stress and strain distributions. The aim of this research is double: (i) to validate a nonlinear finite element wall model and the associated material stress-strain constitutive relationship using the behavior of a real building during the 2010 Chile earthquake; and (ii) to analyze the uncertainty of the response of the building due to changes in model parameters. To validate the response of the wall model, four experimental benchmark RC wall specimens were studied, and model accuracy was evaluated using five parameters: initial stiffness, peak base-shear, ultimate base-shear, maximum displacement, and dissipated energy. A sensitivity analysis was carried out to study the influence of material parameters in the wall response and its damage. The case-study is a 18-story building with 1 basement, which suffered severe damage during the 2010 Chile earthquake, which has been studied by non-linear response-history analysis. Uncertainty in the building response due to three important modeling assumptions was considered: Rayleigh’s damping model parameters; effective elastic bending stiffness of the structural elements; and effect of the vertical ground motion component. Results showed that the proposed model can predict the seismic response of the building with reasonable accuracy by identifying correctly the damage location. This case-study enabled us to assess also the effect of damping in non-ductile structures, the important influence of the slab stiffness in the response, and the effect of the vertical ground motion component in the sequence of damaged walls.
