Nonlinear finite element modeling and response analysis of the collapsed Alto Rio building in the 2010 Chile Maule earthquake.

The 15-story Alto Rio building built in 2006 in the city of Concepción, Chile, was the only modern building that collapsed catastrophically during the February 27, 2010 M_w 8.8 Maule earthquake, resulting in eight human casualties. This building was typical of many medium rise reinforced concrete bearing wall buildings designed and built in Chile during the period 1996-2009. Understanding the mechanism that led to the collapse of the Alto Rio building is of high relevance in the earthquake engineering community. For this purpose, a detailed three-dimensional nonlinear model of the as-built Alto Rio building structure was developed in the OpenSees analysis framework using the beam-truss modeling approach. The geometry of the structure was obtained directly from the architectural blueprints. Realistic cyclic material constitutive models were used for the reinforcing steel and concrete materials. This paper describes in detail the development of the building model. Furthermore, it presents the results obtained from a nonlinear pushover analysis and from a nonlinear time-history analysis using a bi-axial horizontal input ground motion generated by blending time-history ground accelerations recorded at an accelerograph station located 1.2 km from the building and time-history ground displacements recorded at a GPS station located 3.7 km from the building. [ABSTRACT FROM AUTHOR]