There is an inexorable trend for civil engineering structures to become more slender and lightweight, as engineers strive to design more efficient structures with reduced economic cost, reduced carbon footprint and increased flexibility of usage. Unfortunately, due to their reduced mass and stiffness these structures are inherently lively and there is a desperate need for advanced technologies that are capable of ensuring satisfactory vibration performance when people walk, run and jump on them. There are two key issues to address: (1) Technologies are required to deal with existing vibration problems, which are increasingly and widely observed in structures such as floors, footbridges, sports stadia and staircases. Currently available technologies are insufficient to deal with the majority of these problems, which means that extensive and low-tech structural modification schemes have to be employed that are both expensive and highly disruptive. (2) If the ambitions of structural engineers for ever more slender and efficient structures are to be realised, it will be necessary to 'design in' advanced methods of vibration control when developing new structures. This is because many contemporary structures are already being designed at their limits of vibration acceptability. Unfortunately, the new technologies required for this transformative design approach are not yet available. In the last five years, the applicant and his team have carried out exciting research into active control of vibration in floor structures, in which large reductions in vibration have been achieved that are not possible using other floor control technologies. They have also demonstrated that significant material savings may be made using this technology, which has the potential to significantly reduce the carbon footprint of new buildings. This is the main vision for this fellowship and the future, where advanced and intelligent vibration control strategies will become commonplace in structures subject to human dynamic loading. However, a solution that works for floor vibrations from a single person walking is not necessarily going to work for a sports stadium with many thousands of people jumping during a rock concert. Hence, what is required is a required is a complete 'suite' of control technologies, from which the most appropriate solution may be chosen and implemented for any particular vibration problem. In these days of active noise cancelling headphones and semi-active vehicle suspension systems, it is time for these advanced technologies to find their place in civil structural engineering, to solve the unique problems of human-induced vibration. Hence, in this research a comprehensive framework of technologies will be developed, so that the most appropriate technologies may be selected for a particular application. This will be the first time in the world that such a holistic approach has been taken to mitigation of human-induced vibrations. Fundamental research into a range of these technologies, including active, semi-active and hybrid vibration control techniques will be carried out to prove their viability in the civil engineering sector through analytical modelling, laboratory testing and in-the-field implementation. Finally, extensive industrial liaison and public outreach activities are planned to ensure the take-up of these technologies, which is the key way in which this research will benefit UK plc.

There is an inexorable trend for civil engineering structures to become more slender and lightweight, as engineers strive to design more efficient structures with reduced economic cost, reduced carbon footprint and increased flexibility of usage. Unfortunately, due to their reduced mass and stiffness these structures are inherently lively and there is a desperate need for advanced technologies that are capable of ensuring satisfactory vibration performance when people walk, run and jump on them. There are two key issues to address: (1) Technologies are required to deal with existing vibration problems, which are increasingly and widely observed in structures such as floors, footbridges, sports stadia and staircases. Currently available technologies are insufficient to deal with the majority of these problems, which means that extensive and low-tech structural modification schemes have to be employed that are both expensive and highly disruptive. (2) If the ambitions of structural engineers for ever more slender and efficient structures are to be realised, it will be necessary to 'design in' advanced methods of vibration control when developing new structures. This is because many contemporary structures are already being designed at their limits of vibration acceptability. Unfortunately, the new technologies required for this transformative design approach are not yet available. In the last five years, the applicant and his team have carried out exciting research into active control of vibration in floor structures, in which large reductions in vibration have been achieved that are not possible using other floor control technologies. They have also demonstrated that significant material savings may be made using this technology, which has the potential to significantly reduce the carbon footprint of new buildings. This is the main vision for this fellowship and the future, where advanced and intelligent vibration control strategies will become commonplace in structures subject to human dynamic loading. However, a solution that works for floor vibrations from a single person walking is not necessarily going to work for a sports stadium with many thousands of people jumping during a rock concert. Hence, what is required is a required is a complete 'suite' of control technologies, from which the most appropriate solution may be chosen and implemented for any particular vibration problem. In these days of active noise cancelling headphones and semi-active vehicle suspension systems, it is time for these advanced technologies to find their place in civil structural engineering, to solve the unique problems of human-induced vibration. Hence, in this research a comprehensive framework of technologies will be developed, so that the most appropriate technologies may be selected for a particular application. This will be the first time in the world that such a holistic approach has been taken to mitigation of human-induced vibrations. Fundamental research into a range of these technologies, including active, semi-active and hybrid vibration control techniques will be carried out to prove their viability in the civil engineering sector through analytical modelling, laboratory testing and in-the-field implementation. Finally, extensive industrial liaison and public outreach activities are planned to ensure the take-up of these technologies, which is the key way in which this research will benefit UK plc.

The modal properties of a structure include primarily its natural frequencies, damping ratios and mode shapes. Their information is indispensable for design against dynamic loads such as wind, earthquake and human excitation. Uncertainty arises due to the lack of knowledge and modelling limitations and this generally increases project risk. Modal identification has long been recognised as an effective means for uncertainty mitigation in structural dynamics. Theoretically it is possible to identify the modal properties based on only the 'output' vibration response of structures without knowing the 'input' excitation. This type of test, called 'ambient vibration test', has now become the primary and most sustainable means for its high implementation feasibility, robustness and economy. In the absence of loading information and with data collected under uncontrolled field environment, however, the identification results have significant variability and low repeatability. This has limited the economic benefit of ambient vibration tests and undermined the scientific significance of their identification results. This has been well-recognised but there has been no quantitative account for its origin or how to control it. This project aims at developing a comprehensive fundamental methodology for quantifying and managing the uncertainties of the modal properties of civil engineering structures identified from ambient vibration data. At the scientific core is a set of 'uncertainty laws', analogous to the laws of large numbers of data in classical probability, that expresses fundamentally the identification uncertainty of modal properties explicitly and quantitatively in terms of test configurations such as measurement noise, environmental load intensity and the number and location of sensors. Due to complexity of the problem, it is unlikely to obtain insightful results for general situations. The project aims at fundamental expressions with insights governing the dominant behaviour of the remaining identification uncertainty under realistic situations. The project objective is achieved through a comprehensive programme comprising fundamental theory development, extensive verification with synthetic, laboratory and field data, and knowledge transfer with industry. A practical guide for planning and performing ambient vibration test shall be produced incorporating scientific findings of the project and experience of the team members with input from industry partners.