Nicholas A Alexander
PhD(UCL), BSc(Eng) , CMath, MIMA, CSci, GMICE
Dr Nicholas A Alexander is a Senior Lecturer in Structural Engineering at the University of Bristol. His main research areas are Earthquake Engineering and Nonlinear dynamics. He holds a first class undergraduate degree in Civil Engineering at University College London (UCL) and was awarded the Institution of Civil Engineers (ICE) prize. His PhD is in nonlinear dynamics (UCL) supervised by Prof JMT Thompson. He is a member of the Institute of Mathematics, a Chartered Mathematician (UK) and a Chartered Scientist (UK). He has supervised, to date, 17 PhD students. He has over 100 publications in international journals and conferences. Has an h-index of 16 in Google Scholar. His paper on the dynamics of a nonlinear tuned mass dampers was listed in most cited papers in Journal of Sound & Vibration (2007-11). His paper on offshore wind turbine soil-structure interaction was listed in the most cited papers in Soil-Dynamics and Earthquake Engineering (2011-15). He is a Co-I of the "SAFER: Seismic Safety and Resilience of Schools in Nepal" EPSRC grant £1.6m (2017-2019). He is a Co-I of an EU Horizon 2020 grant €1m, (2016-2018) and the PI of the EPSRC Global Challenge Institutional Sponsorship grant (2016) "A low-cost, sustainable technology for earthquake-resilient urban infrastructure in DC". He was Co-I on ESPRC: grant EP/D035562/1, “Workshop: Info-gap analysis of engineering systems: Robust decisions under severe uncertainty” (2006)
All things dynamical !
- Behaviour of corroded reinforced concrete structures subjected to seismic excitations - How do we model these degrading systems ? Using advanced constitutive material models that have be validated experimental tests.
- Behaviour of nonlinear moment resisting frames under seismic excitation - how do you develop robust low order models for complex nonlinear dynamical systems that are subjected to uncertain loading histories? Are nonlinear response spectra and performance based approaches the way forwards?
- Pre-stressed frames with opening joints that allow structures to soften but remain undamaged after earthquakes. - can we design structures with morphing geometry that remains undamaged after earthquakes?
- Nonlinear tuned mass dampers - can we improve on a linear tuned mass damper? What advantages are gained by the nonlinearity? Are smart semi-active devices the way forwards?
- All analysis in earthquake engineering is predicated on the accurate processing of ground motion timehistories. We use state of the art signal processing ideas such as wavelet decomposition and denoising, Wigner-ville methods, Bispectra, Volterra Kernels, adaptive total least squares etc. - can we determine robust and accurate measure of displacement timehistories from recorded accelerations? (thought to be impossible because of influence of low frequency noise)
- Analysis of long structures that are subjected to differential seismic excitation both in acceleration and displacement; i.e. the multi-support excitation of bridges - How should we analyse these structures to take into account all the true complexity of spatial-temporal variation in ground motion?
- Human-Structure interaction - dynamic feedback between structures and people that can produce complex and unexpected resonances - can we model human beings responses to moving structures and hence the feedback into structures?
- Understanding the dynamics of piled structures, using a nonlinear dynamics perspective - can we model these systems to understand both short terms and long term behaviour?
- Vulnerability of cities; structure-soil-structure interaction - do buildings near to one another interact dynamically? Does the assessment of vulnerability of such systems require a detail knowledge of such dynamic, nonlinear interactions?