Seismic Behaviour of U-Shaped Walls

• Head of Project: Prof. Dr. A. Dazio
• Assistant: Dr. K. Beyer
• Partner: -

U-shaped walls are frequently used to provide reinforced concrete (RC) buildings with lateral strength. Their shape not only provides strength and stiffness in any horizontal direction, it is also well suited to accommodate lift shafts or stair cases. Although U-shaped walls are very popular in practice, experimental results on their behaviour under seismic loading are very sparse, and codes do not provide detailed guidelines for their design when a ductile behaviour is aimed for. The principal objective of this research project is to contribute towards understanding the flexural, shear and torsional stiffnesses as well as the strength and the displacement capacity of U-shaped walls when subjected to seismic loading.

The research project consisted of an analytical and an experimental part. In the experimental part two RC U-shaped walls (scale 1:2) with different wall thicknesses were subjected to quasi-static cyclic loading. Both test units represented the lower third of a U-shaped wall in a six-storey building. The walls were subjected to bi-directional loading and to torsion. In the numerical part of the project the U-shaped walls were analysed using different programs aiming at simple models which can also be used in engineering practice. These models were compared to the evidence gained during the experimental part of the project and recommendations regarding the modelling of U-shaped walls were formulated.

In a forthcoming second phase of the project the effect of the loading history on the hysteretic behaviour of U-shaped walls as well as the force-deformation characteristics of non-capacity designed walls will be investigated. Finally, a comprehensive set of recommendations for the design of buildings featuring U-shaped walls will be formulated.