Seismic Performance of Yielding Columns Supported by Rocking Foundations: A Computational Study
Abstract
The effectiveness of foundation rocking as a seismic energy dissipation mechanism to reduce shake demands is studied by the use of a finite element numerical model consisting of a realistic structure and a soil-foundation interaction model. While both fixed base and rocking foundation systems performed satisfactorily during relatively small shaking events, rocking foundation systems exhibited superior performance during strong shaking events. Furthermore, rocking foundation design reduced the peak deck drift due to flexure, peak acceleration on the deck, and the column base moment by more than 50% when compared to conventional design. By intentionally reducing the rocking coefficient smaller than base shear coefficient, the beneficial effects of rocking foundations were fully utilized. It was shown that a slight increase in footing embedment and/or initial shear modulus of soil has the potential to improve settlement-rotation behavior of the foundation significantly, while still mobilizing rocking behavior and dissipating seismic energy.