Influence of biaxial interaction of hysteretic restoring base forces on wind-induced inelastic response of base-isolated tall buildings

This study addresses the influence of biaxial interaction of hysteretic restoring forces of base isolation system on wind-induced response of base-isolated tall buildings. Both buildings with and without eccentricity in center of resistance are considered. Response history analysis is carried out to characterize the coupled responses of a square-shaped base-isolated tall building. A comprehensive parameter study is presented which covers a wide range of yielding level, response ratio and correlation of alongwind and crosswind base displacements. The results demonstrate that the biaxial interaction leads to increase in low-frequency component and decrease in resonant component of lower inelastic base displacement. However, the increase of low-frequency component of base displacement does not affect the upper building response relative to base isolation system. As a result, the upper building response is reduced by the influence of biaxial interaction. The biaxal interaction also results in fast growth of time-varying mean alongwind base displacement. The increase of low-frequency component can be significant when the yielding level of higher response is significant and two translational base displacements are quite different in magnitude. The correlation of two translational base displacements enhances the influence of biaxial interaction. For the base-isolated building with eccentricity, the alongwind and crosswind base responses are closer in magnitudes thus are less influenced by the biaxial interaction.

Automated summary

This study investigates the impact of biaxial interaction of hysteretic restoring forces of base isolation system on the wind-induced response of base-isolated tall buildings. The results show that the biaxial interaction increases the low-frequency component and decreases the resonant component of lower inelastic base displacement. However, this increase in low-frequency component does not affect the upper building response relative to the base isolation system. Additionally, the biaxial interaction leads to a rapid growth of the time-varying mean alongwind base displacement. The increase in low-frequency component is significant when the yielding level of higher response is significant and the two translational base displacements are quite different in magnitude. The correlation of the two translational base displacements enhances the influence of biaxial interaction. For base-isolated buildings with eccentricity, the alongwind and crosswind base responses are less influenced by biaxial interaction.