Multi-objective performance-based design of tall buildings using energy harvesting enabled tuned mass-damper-inerter (TMDI) devices

This project focuses on wind and/or earthquake excited buildings whose oscillatory motion is controlled via, the commonly used, tuned-mass-damper (TMD): an additional free-to-vibrate mass mounted to the top of buildings via springs and viscous dampers. TMDs are optimally designed (tuned) such that kinetic energy is transferred from the building ("primary structure") to the TMD mass and dissipated by dampers. In general, larger TMD mass achieves better vibration suppression, but this is limited by architectural and structural (weight) constraints. Control of wind induced vibrations require TMD mass of 1%-5% of total building mass and this ratio can reach up to 15-20% or more for severe earthquake excitations.

The project:
-exploits the mass amplification effect of flywheel-based mass amplification devices (MADs) to achieve different apparent mass for the TMD+MAD configuration without changing the TMD weight;
-explores the potential of energy harvesting from wind-induced building vibrations by containing the MAD's flywheel within a magnetic field such that rotational kinetic energy is transformed into electric energy;
-establishes a "pro-active" control paradigm within a multi-objective performance-based structural design framework: the apparent mass of the TMD+MAD changes through gearing according to pre-set "optimally" tuned values for different objectives such as optimal vibration suppression at serviceability state for user comfort- "medium" apparent mass; maximization of energy harvesting during off-hours in office buildings- "low" apparent mass; minimisation of potential for structural damage at ultimate state {extreme wind fronts/downbursts or earthquakes}- "large" apparent mass). These changes can be "programmable" and informed by weather forecast and/or by early warning earthquake systems achieving "smart"/adaptive, energy efficient and resilient structures.

The proposed research idea is potentially transformative because it:
1)will allow for ever-more slender, taller, cost-effective, and aesthetically pleasing tall buildings in congested urban environments (e.g., London, Tokyo, NY, etc. where land use optimisation is essential) through the ability to control wind-induced (and/or earthquake) oscillations by more lightweight TMDs compared to the ones used today. These buildings will also be safer in more aggressive climate environments and with lower CO2 footprint through effective energy harvesting from large amplitude oscillations.
2)will change the "purpose" and functionality of building structures. Through the pro-active control framework, an office building can be designed to ensure absolute comfort to occupants during work hours even under future ever extreme climate change-induced winds for which
it has not been initially been built for. During off-hours the same structure becomes a flexible cantilever producing renewable energy from wind.

The potential ultimate impact ot the project is:
-TECHNOLOGICAL: sparkling considerable new technological R&D and commercialisation opportunities for UK and international manufacturers of vibration suppression and energy harvesting equipment for civil and mechanical/automotive applications globally. SOCIETAL: enhancing infrastructure users' comfort, aesthetics, and structural safety and resiliency under future aggressive environments due to climate change. ECONOMICAL: stimulating the manufacturing sector, the construction industry, and the engineering consultancies towards world-class structures optimally designed for energy harvesting and vibration control; enhancing existing and future infrastructure value and economic life-cycle. ENVIRONMENTAL: reducing energy use and CO2 footprint of buildings through optimum wind energy harvesting, less material usage, and better land usage since more tall buildings can be built in a cost-effective manner.

This project develops (analytically and computationally) an innovative energy harvesting-enabled lightweight flywheel-based mass amplification mechanical device (inerter) and uses it to optimally design tuned mass-damper-inerter (TMDI) equipped tall structures following a novel pro-active control approach within a multi-objective performance-based framework. This new technology and structural design approach will:
1)allow for ever-more slender, taller, cost-effective, and aesthetically pleasing high-rise buildings in congested urban environments through the ability to control wind-induced (and/or earthquake) oscillations by more lightweight tuned mass dampers (TMDs) compared to the ones used today. These buildings will also be safer in more aggressive climate environments and with lower CO2 footprint through effective energy harvesting from large amplitude oscillations.
2)potentially transform the "purpose" and functionality of other civil engineering structures incorporating TMDs for vibration suppression such as (foot-) bridges, off-shore platforms, and wind turbines.
To this end, it is anticipated that, apart from the academic research community (being both a beneficiary and a short-term critical facilitator in achieving the anticipated economic and societal impact), the main beneficiaries of this research project will be:
a) in the short-term, (i) manufacturing companies/industry of vibration suppression/isolation and energy harvesting equipment for civil and mechanical/automotive applications. In particular, this project sparks considerable new technological R&D and commercialisation opportunities for such companies and manufacturers to address the world market needs for customized, lightweight, cost-effective electro-mechanical based vibration absorbers and energy harvesting devices. An expanding market for this device is foreseen as the World's needs for resilient and sustainable tall buildings in congested City centres of developed and developing countries increases together with wind-induced demands for new and existing structures due to climate change. (ii) Structural design offices, consultants, and practicing engineers undertaking analysis and design of tall structures.
b) in the mid-term, owners, asset managing agencies and maintenance contractors of tall buildings and of other civil infrastructure incorporating TMDs for vibration suppression such as (foot-) bridges, off-shore platforms, and wind turbines. The use of lightweight energy harvesting enabled TMDI systems will reduce the overall construction/erection cost of buildings yielding smart, resilient, and sustainable structures better equipped to face future climate change-related challenges. Thus, it will add value to structured assets by reducing insurance costs, enhancing occupants' comfort, and reducing structures' carbon footprint.
c) in the long-term, everyday users of civil engineering structures incorporating the TMDI technology and communities of major city centers and metropolitan areas.
Nevertheless, upon completion of the project, the following additional step is required to realise the aforementioned potential technological, economical, and societal impact to the above beneficiaries: to prototype/manufacture and to validate experimentally the new energy harvesting-enabled flywheel-based mass amplification device (inerter) to be developed in this project. This requires further multi-disciplinary experimental research undertaken by consortia of industrial partners and academic research groups of different fields (including full-scale hybrid testing and scaled-down wind tunnel and shaking table testing). To this end, focus will be given during the lifetime of this project to facilitate impact to the academic community and to the short term beneficiaries identified above which, in turn, will ensure that further experimental research will be conducted exploiting/applying, building on, and expanding the outcomes of this project.