Seismic Behavior of Frame-Wall-Rocking Foundation Systems. I: Test Program and Slow Cyclic Results.

The mechanism of foundation rocking has received much attention recently due to its appealing seismic resistant features, namely, self-centering tendency and energy dissipation capability. It is well recognized, however, that other inelastic mechanisms will contribute to a system's seismic resistance. Considering the strength difference between a rocking footing and a shear wall structural fuse, and the system symmetry, six different two-story-two-bay frame-wall-foundation building models were constructed and tested in a geotechnical centrifuge. In this paper, the test program and experimental results when the models were subjected to slow cyclic loading are presented. A companion paper presents results from the dynamic phase of testing. Results indicate that, with the aid of foundation rocking, the system behaves in a ductile and stable manner with no strength degradation, even when the model is pushed to a drift of more than 2.5%. Importantly, when structural and foundation component strengths are approximately equal, the hysteretic energy is reasonably distributed among the superstructure inelastic components and the rocking foundations. Finally, numerical analyses predictions demonstrate comparable local and global response to measurements obtained during the experiments. [ABSTRACT FROM AUTHOR]