Damping dissipation analysis of damped outrigger tall buildings with inerter and negative stiffness considering soil-structure-interaction

This paper analyzes the damping dissipation of damped outrigger tall buildings with inerter and negative stiffness considering soil-structure-interaction (SSI). A unified characteristic equation is established concerning different soil conditions and outrigger systems. By solving the unified characteristic equation, the multi-mode damping effect are parametrically investigated to evaluate the influence of SSI on tall buildings installing conventional outrigger (CO), conventional damped outrigger (CDO), negative stiffness damped outrigger (NSDO), and inerter damped outrigger (IDO). Then, the vibration performances of damped outrigger systems considering SSI are evaluated under both wind and earthquake loadings. Two key points are highlighted: (i) the interaction between the soil rocking behavior and the outrigger rotation in tall buildings; (ii) the influence of frequency variation caused by SSI on the damping effect of IDO and NSDO with frequency-dependent/independent features. Analyzing results indicate that a stronger CO would increase the damping effect of the foundation soil as long as the CO is not installed at lower stories. The SSI effect will render CDO itself undergo more dissipation for the first mode but limit CDO's damping effect on higher modes. IDO can be effective for the target mode, but is very sensitive to SSI effect due to its frequency-dependent feature; a re-optimization of IDO to proper vibration mode is always needed in resisting wind and earthquake. In contrast, NSDO's damping effect is less sensitive to the SSI effect and can be effective to multiple modes due to its frequency-independent feature. For example, the majority of the input energy from winds (over 90%) and earthquake (over 70 %) will be dissipated by NSDO, and such high values change little under SSI conditions, validating NSDO can provide effective and robust control to multiple hazards.