Performance of slender reinforced concrete structural walls under significant lateral loads

Special reinforced concrete structural walls are the most common lateral force-resisting system in reinforced concrete construction in the United States. However, recent earthquakes in Chile have indicated that flexure-dominated walls may still exhibit low-ductility failure mechanisms. The National Institute of Standards and Technology (NIST) has initiated a multi-phase large-scale testing project in order to better understand the behavioral implications on ductility of several design parameters, and develop code recommendations based on findings. The first phase focuses on boundary element detailing, wall configuration, reinforcement ratio and configuration, and axial load ratio. In addition to large-scale walls, subcomponent-scale tests, which are indicative of boundary elements in reinforced concrete walls, are being conducted to provide preliminary data. Specimens are tested cyclically in tension and compression, with some subjected to large tension strains prior to cyclic loading. Results from the first two tests indicate that sections exposed to significant tension strain have a significantly reduced compressive capacity. Damage progression during tests also suggests that the buckling behavior observed in the 2010 Maule Chile earthquake may be the result of localized damage that occurs beyond the section's compressive capacity, rather than the cause of it. Additionally, data shows that rectangular sections may be more difficult to adequately confine than previously thought.