Three dimensional inelastic models to assess earthquake damage of reinforced concrete wall buildings

Abstract

A non-ductile failure has been observed in some reinforced concrete structural wall buildings during recent earthquakes in Chile and New Zealand. Although substantial experimental and analytical research has been conducted, several questions still remain about the behavior of structural walls and their 3D interaction with the rest of the structure. This article compares response results of two different inelastic finite element (FE) models in one real building in Santiago damaged during the 2010, Chile earthquake. In this structure, brittle behavior was localized in the first-basement and first-story. The first model is a 3D FE model developed in the software DIANA and uses 4-node shell elements. The inelastic behavior of concrete was modeled using the total strain rotating crack model, and reinforcement using an embedded formulation. The second model is also a 3D-linear elastic FE model of the building using ETABS, which combines an inelastic force-based fiber beam element (FFE) recently proposed for concrete walls, which includes regularization, steel buckling and fracture, and its complex cyclic behavior. Inelastic dynamic analyses were performed for both models considering different ground motions recorded relatively close to the building during the seismic event. Dynamic results from both models are analyzed and compared with damage observed during the earthquake. Additionally, a comparative analysis of each model is discussed herein. Results show that the observed damage pattern is accurately predicted by both analytical models at reasonable computational cost. Both models predict an important increase in axial load in the walls, which seems to be critical in producing the localized brittle flexural-compressive failure observed. Consequently, these models could be used in practice to assess the condition of existing structural wall buildings and propose effective retrofit strategies.