Stability of thin RC walls

Recent earthquakes in Chile (2010) and New Zealand (2011) revealed the risk related to out-of-plane failures of reinforced concrete walls. While the walls in Chile and New Zealand had all thicknesses of more than 15 cm, there are regions in the world where—due to material costs—walls as thin as 8 cm are used for the construction of buildings of several stories.
The fear is that such walls might collapse in the event of a significant earthquake. Such construction exists in particular in Latin American countries, where city administrations are required to provide large amount of housing for low income population.
At EPFL, through grants from SNF and Codev and in collaboration with researchers from Colombia, a country that is heavily affected by this problem, we tested walls typical for such construction practice simulating the earthquake loading with up to 5 servo-hydraulic actuators.
The tests are the first tests on RC walls that developed large out-of-plane displacements along the wall height for which the entire 3D displacement field was measured. For this purpose we used two complimentary optical measurement systems that are available in the laboratory (Optotrak, an LED-based system, and digital image correlation).
Using the same measurement techniques, we investigated more in depth the various parameters influencing the out-of-plane response by subjected 12 isolated boundary elements to tension-compression cycles.
Thanks to these measurements, we could identify the mechanisms behind the out-of-plane failure of such thin walls. Moreover, the optical data allows a detailed validation of finite element models with regard to their capacity of predicting out-of-plane failures, which was not possible before. The data set is public and is used by several research groups around the globe for model validation. The research results have been presented to researchers and practicing engineers in Colombia and beyond.
EPFL Laboratory: Earthquake Engineering and Structural Dynamics Laboratory
Project participants: EPFL: Angelica Rosso, Lisandro Jimenez, Dr. João Almeida, Prof. Katrin Beyer

School of Engineering of Antioquia (Colombia): Prof. Carlos Blandón Uribe

University of Medellin (Colombia): Prof. Ricardo Bonett Díaz

Universidad del Valle (Colombia): Prof. Aydée Patricia Guerrero

Universidad del Norte (Colombia): Prof. Carlos Alberto Arteta Torrents