In the HARVEST-WIND project, optimally designed tuned mass-damper-inerters (TMDIs) will be considered to meet code-prescribed serviceability criteria in typical wind-excited tall buildings subject to vortex shedding effects in a performance-based design context. The TMDI, couples the classical tuned-mass-damper (TMD) with an inerter, a two-terminal device resisting the relative acceleration of its terminals, achieving mass-amplification and higher-modes-damping effects compared to the TMD. Energy Harvesting (EH) potential of this new system will be also investigated by adding in parallel to the inerter an electromagnetic motor, obtaining a device (named EH-TMDI) for simultaneous EH and vibration suppression in wind-excited tall buildings.
A benchmark 74-storey building will be considered, where TMDI is added to the structural system assuming ideal linear inerter behaviour and computationally efficient frequency domain will be adopted in structural analyses. The TMDI is optimally designed for stiffness, damping, and inerter constant parameters via a standard numerical optimization search, for a range of pre-specified attached TMDI mass values. The goal is to shown that the TMDI can achieve more lightweight construction in the design of new code-compliant tall buildings against wind and that significant EH skills are available by the varying inertance capabilities of the system.
HARVEST-WIND makes the following original contributions to the state-of-the-art:
1) Conceptual design, analytical and numerical modelling of EH-TMDIs for VC and EH in tall buildings. The use of electromagnetic motors in conjunction with an inerter for EH from oscillating civil engineering structures is hindered by the large magnitude of the involved forces, which are due to the large oscillating mass of the TMD (up to 2% of the total mass of the building). The developed device will overcome this problem by reducing the effective mass of the TMD thanks to the mass amplification effect introduced by the inerter, leading small-mass TMDIs to have the same performances of a large mass ordinary TMDs. However, this coupling adds complexity to the required models capturing the dynamic behaviour of the system. Therefore, advanced FE models and analytical simplified models will be developed for the electromechanical characterization of the EH-TMDI device.
2) Multi-objective optimum design of EH-TMDI equipped tall buildings achieving code-compliant structural performance while maximizing the harvested energy. The optimum design of VC systems against tailored application-dependent performance criteria uses standard numerical techniques and is well-studied in the literature. However, the optimal design of EH-TMDIs involves two always conflicting objectives: reducing vibrations and maximizing the harvested energy. This problem is handled in HARVEST-WIND by appropriate formulation of the EH-TMDI design problem by defining two main service condition: given a host structure and input loading, the first condition is given by the scenario where buildings' occupant are inside (e.g. working hours for office buildings), and aiming to meet code-compliant structural performance requirements as constraints to the optimization problem, the second service condition is when occupants are not inside the building (e.g. off-working hours for offices), where both the inertance and damping are opportunely "de-tuned" with respect to their optimal values for VC in order to allow large vibration for the building and EH.