Dr Haris Alexakis
Lecturer, Civil Engineering | Aston University
Birmingham, UNITED KINGDOM
Dr Alexakis conducts research on smart/digital infrastructure for sustainable civil engineering systems.
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Biography
Haris is lecturer in Civil Engineering at Aston University, UK and academic visitor at Cambridge University, UK. His research currently focuses on smart and resilient infrastructure by combining multi-sensing information, structural analysis and statistical modelling. As research associate at the Cambridge Centre for Smart Infrastructure and Construction, he developed an autonomous structural health monitoring system with acoustic emission sensors, fibre optic strain and temperature sensors, and high-sensitivity accelerometers for detecting deterioration in ageing bridges. Before his appointment at Aston and Cambridge, he was adjunct assistant professor at the University of Central Florida, USA. He holds a bachelor’s and master’s degree in Civil and Structural Engineering, a master’s degree in Seismic Design of Structures and awarded a PhD in Limit Analysis and Earthquake Resistance of Masonry Structures from the University of Patras, Greece. He worked for a decade as consultant structural engineer, leading the restoration and seismic reinforcement of several historic structures.
Areas of Expertise (6)
Ageing Infrastructure
Smart Bridges
Structural Health Monitoring
Structural Analysis of Masonry/Historic Structures
Signal Processing and Data Analytics
Structural Dynamics
Accomplishments (1)
Rail Visionary Award, New Civil Engineer TechFest
2019
Education (3)
University of Patras: Ph.D., Civil Engineering 2013
University of Patras: B.Sc. & M.Eng., Civil Engineering 2005
University of Patras: M.Sc., Seismic Design of Structures 2007
Links (2)
Media Appearances (4)
Turkey-Syria earthquakes: What lessons can the ground engineering sector learn?
Ground Engineering online
2023-02-20
The foundation design, as Aston University civil engineering lecturer and structural engineer Haris Alexakis explained, is after all one part of the “holistic structural design required to achieve the desired seismic performance”.
UK engineers, seismologists and geologists to embark on post-earthquake mission to Turkey
Ground Engineering online
2023-02-16
Aston University civil engineering lecturer Haris Alexakis commented: "Poor implementation of seismic codes and inadequate quality control in construction details and materials are in many cases the reasons why some modern buildings completely crumple within the first seconds of a strong ground shaking.
Turkey earthquakes: why did thousands of buildings collapse and why are contractors being arrested?
NationalWorld online
2023-02-14
Aston University civil engineering lecturer Haris Alexakis told NationalWorld that poor implementation of seismic codes and inadequate quality control in construction were often why modern buildings “completely crumple within the first seconds of a strong ground shaking”.
Fibre optic sensors installed on M6 concrete bridge as part of CSIC multi-sensing systems-integration project
Cambridge Centre for Smart Infrastructure and Construction online
2020-12-08
“Ultimately, this project aims to provide an early warning monitoring system that will enable improved maintenance strategies and systems for ageing highway assets,” said Dr Haris Alexakis, who is part of the team installing the fibre optic strain sensors.
Articles (3)
Distributed dynamic fibre-optic strain monitoring of the behaviour of a skewed masonry arch railway bridge
Journal of Civil Structural Health Monitoring2021 Skewed masonry arch railway bridges are common, yet their structural behaviour under typical working loads, along with gradual changes in behaviour due to degradation, can be difficult to determine. This paper aims to address this problem through detailed monitoring of a damaged, skewed masonry arch railway bridge in the UK, which was recently repaired. A comprehensive Structural Health Monitoring system was installed, including an array of fibre-optic Fibre Bragg Grating (FBG) sensors to provide distributed sensing data across a large portion of the bridge. This FBG monitoring data is used, in this paper, to investigate the typical dynamic structural response of the skewed bridge in detail, and to quantify the sensitivity of this response to a range of variables. It is observed that the dynamic bridge response is sensitive to the time of day, which is a proxy for passenger loading, to the train speed, and to temperature. It is also observed that the sensitivity of the response to these variables can be local, in that the response can differ throughout the bridge and be affected by existing local damage. Identifying these trends is important to distinguish additional damage from other effects. The results are also used to evaluate some typical assumptions regarding bridge behaviour, which may be of interest to asset engineers working with skewed masonry arch bridges.
Fibre Optic Sensing of Ageing Railway Infrastructure enhanced with Statistical Shape Analysis
Journal of Civil Structural Health Monitoring2021 Developing early-warning sensor-based maintenance systems for ageing railway infrastructure, such as masonry arch bridges, can be a challenging task due to the difficulty of identifying degradation/damage as the source of small, gradual changes in sensor data, as opposed to other environmental and loading effects. This paper offers a new method of applying statistical modelling and machine learning to enhance the interpretation of fibre optic sensing data, and, therefore, improve deterioration monitoring of railway infrastructure. Dynamic strain and temperature monitoring data between 2016 and 2019 from a fibre Bragg grating (FBG) network installed in a Victorian railway viaduct are first presented. The statistical shape analysis adopted in this study is modified to track changes in the shape of FBG signals directly linked to train speed and dynamic strain amplitudes. The method is complemented by a support vector machine, which is trained to identify different classes of trains. After distinguishing train types, dynamic strain was found to be clearly correlated to temperature, verifying previous findings. No correlation with train speed was observed. The integrated system is then able to compensate for changes in the structural performance due to variations in train loading and ambient temperature, and identify changes in dynamic deformation caused by degradation, in an order comparable to the signal noise (± 2 micro-strain). As a result, the new procedure is shown to be capable of detecting small magnitudes of local degradation well before this degradation manifests itself in typical global measures of response.
Damage identification of brick masonry under cyclic loading based on acoustic emissions
Engineering Structures2020 Ageing infrastructure, such as masonry railway bridges, suffers from structural deterioration due to fatigue loading. This paper presents an experimental study of brick masonry deterioration under gradually increasing cyclic loading with the aid of Acoustic Emission (AE) sensors. Two masonry beams were tested in the laboratory under similar stress conditions that masonry arches experience during train loading. An in-house AE monitoring system was developed for this study allowing both feature-based and waveform-based AE analysis. In the lab tests, different modes of damage were activated, such as tensile bond failure, brick and mortar crushing, diagonal shear failure and joint sliding. Feature-based AE analysis shows an increase in cracking rate before brittle failure events that is not necessarily accompanied by an increase in deformation rate. Statistical analysis reveals clear trends in AE results that correlate to different damage stages. The paper discusses how these findings can be leveraged to develop real-time structural alert systems that could provide early warning of damage before a significant increase in dynamic deformation occurs.
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