Piezoelectric materials present the capability of converting mechanical to electrical energy or vice versa. Those devices have an interesting point of study since their application adapts to a new circumstance. Hence, the present work relates the implementation of a piezoelectric material embedded in the structural building internal connections, adopting the concept of smart buildings/structures. The project aims to develop piezoelectric-dampers (PiDs), which are composite elements made by piezoelectrics, steel, and rubber. PiDs are located in the bracing-to-beam connections of the buildings and work by transforming the wind-induced oscillations in electrical usable energy, and this phenomenon occurs due to the piezoelectric components they own. It is expected that the harvested energy is directly proportional to the device's experimented frequency of vibration. EH from piezoelectric devices is not so implemented in buildings due to reasons, such as the deficiency of piezoelectric materials in bearing loads and low frequencies of the vibrations occurring in buildings. The project tends to promote the concept of energy harvesting (EH) from piezoelectric devices in structural building's connection at macro scale. Hence, the PiDs present an innovative coupling between the piezoelectric block and the load-carrying member as steel and rubber, allowing the piezoelectric-blocks to work in nonlinear/high-frequency regimes arising from buckling or impact, aiming a higher efficiency. Last, the energy produced by those devices will benefit wireless sensors used in building automation and structural health monitoring systems. It presents an idea of sustainability, such as, production of a new power source and avoiding the use of cables. In addition, another point of the project is the study of a rheological model to understand the influence of PiDs on structural damping.
a) Innovative devices/technology. EH-enabled composite PiDs connections in dynamically excited tall buildings using piezoelectric materials. Conceptual design and electromechanical modeling of PiDs will be conducted by a bottom-up approach. Novel aspects in PiDs conception are: i) their nonlinear functionality (buckling or impact dynamics); ii) their macro-scale (coupling piezoelectric materials with materials carrying large forces, e.g. rubber, steel). These aspects will bridge current knowledge gaps hindering usage of pzEH in civil structures, and will lead to the following ground-breaking expected results:
- revolutionary unconventional structural connections will be developed;
- access of civil engineers to piezoelectric as a new, smart, construction material will be facilitated.
b) Novel, approaches/methods for Civil Engineering design by the definition of a novel multi-performances approach for PiDs-equipped tall buildings for code-compliant structural performance against service and extreme/accidental loads and EH maximization towards energy autonomous BA and SHM. PBD of tall buildings is one of the primary research areas for the PI and collaborators. Further, optimal design of SHM systems involves optimal placement of sensors in a given structure irrespective of available power source locations and/or optimal data sampling and wireless transmission. However, the project idea addresses a significantly different problem from the above (not addressed before since PiDs or any other similar technology did not exist) involving the optimal placement of PiDs (based on stress concentration and optimal sensors location criteria) to maximize EH (objective function) while meeting code-prescribed performance requirements (taken as constraints) for wind forces. The novelty lies in the optimization criteria which are based on the diffuse self-powering and wireless unique characteristics of the proposed system. This point will lead to the following ground-breaking expected results:
- a new analytical, multidisciplinary (electro-mechanical) theory representing the behaviour of PiDs in large-scale structure will be formulated;
- a new breed of smart energy-autonomous structures will change the way of designing, constructing and perceiving civil engineering structures;