Design Methodology for Unbonded Post-Tensioned Rocking Walls

Unbonded post-tensioned rocking walls have demonstrated superior seismic performance with greatly reduced damage and exceland representative research on rocking walls are summarized in this paper. Some inconsistencies and voids in the major design parameters for rocking walls are identified. A brief description is provided for two rocking-wall specimens tested under quasi-static cyclic loading. Force flow and failure mechanisms of rocking walls observed from the tests were studied, and it is discovered that they are very different from those of special structural walls. The test data showed that the concentration of compressive strain in concrete at the corners of rocking walls was a local behavior such that the need for confinement reinforcement higher above the toe region was diminished. Fiber grout weaker than concrete in rocking walls used as ductile bearing materials at the wall-foundation interface is a reasonable alternative to ACI 550.7. Design recommendations for height and volumetric ratio of confinement reinforcement are provided. A requirement for the aspect ratio of rocking walls stricter than that in ACI 550.7 is proposed to prevent shear sliding of the walls.