Thin RC walls

Latin American city administrations need to provide large amount of housing for low income population. As the cost of space has increased significantly, one of the most common solutions is the construction of medium to high rise reinforced concrete wall buildings. Most of these new residential buildings are constructed with very thin walls and a light amount of reinforcing steel. A survey showed that about 40% of the walls of buildings in Colombia are as thin as 8 cm (C. Blandon, 2015). It is therefore to be feared that these walls might fail due to out-of-plane instability during earthquake loading. Such wall failure would not only compromise the horizontal stiffness and strength of the building but would also lead to the loss of the axial load bearing capacity of the wall. The importance of out-of-plane failures on wall response was emphasised by the performance of walls during the earthquakes in Chile (2010, Mw 8.8) and New Zealand (2011, Mw 7.2), in which several walls developed large out-of-plane displacements. These walls were, however, at least 15 cm wide and featured two layers of reinforcement. It is therefore to be feared that buildings with much thinner walls and a single layer of reinforcement can perform very poorly during a future earthquake. Besides, walls in such buildings have typically a low axial load ratio, and hence when subjected to lateral loads they are more prone to develop significant tensile strains in their end regions, which is the main parameter governing instability. Some features of the wall configurations that are currently constructed in Colombia can be found in existing buildings in Europe and the United States.

The objective of our research is to understand experimentally and describe analytically the mechanisms behind the out-of-plane response of reinforced concrete walls with a single layer of reinforcement. To gain insights into these mechanisms we conduct extensively instrumented experimental tests and numerical simulations. For this purpose, two thin walls were tested under uni- and bi-directional quasi-static cyclic loading. The walls developed large out-of-plane displacements, which eventually led to a crushing failure. These tests are the first wall tests for which the entire out-of-plane displacement profile was recorded using optical displacement measures, and yielded new insights into the development of out-of-plane instability. The influence of further parameters (e.g., wall thickness, loading history, reinforcement content, reinforcement diameter, eccentricity of reinforcement layer with regard to wall axis) on the stability of the boundary element has been addressed during a recent experimental campaign featuring cyclic tension-compression tests on reinforced concrete columns. A workshop on the behaviour of buildings with thin walls was organized in June 2017 during the VIII Colombian Conference on Earthquake Engineering, gathering several national and international experts.

 Tests on thin walls under uni- and bi-directional loading. 
Tension-compression tests on boundary elements.
Beam-column element model for simulating the out-of-plane response of boundary element.

  • Article:
    • Stability of thin reinforced concrete walls under cyclic loads: state-of-the-art and new experimental findings [journal link]
    • Tests on thin reinforced concrete walls subjected to in-plane and out-of-plane cyclic loading [journal link]
    • Instability of thin concrete walls with a single layer of reinforcement under cyclic loading: numerical simulation and improved equivalent boundary element model for assessment [journal link]
    • Cyclic tensile-compressive tests on thin concrete boundary elements with a single layer of reinforcement prone to out-of-plane instability [journal link]
  • Dataset:
  • Funding
  • Collaboration:
    • Prof. Carlos Arteta (North University, Colombia)
    • Prof. Carlos Blandón (Universidad EIA, Colombia)
    • Prof. Ricardo Bonett Díaz (University of Medellín, Colombia)
    • Prof. Patricia Guerrero (Universidad del Valle, Colombia)
    • Prof. Julian Carrillo (Nueva Granada Military University, Colombia)
    • Prof. Rajesh Dhakal (University of Canterbury, New Zealand)
    • Prof. Stefano Pampanin (University of Canterbury, New Zealand)
    • Prof. Beatrice Belletti (University of Parma, Italy)