Now showing 1 - 10 of 86
  • Publication
    Structural health monitoring of reinforced concrete beam using piezoelectric energy harvesting system
    (INRIA Rennes - Bretagne Atlantique, 2014-07-11) ; ; ; ;
    There has been focus in recent times in the creation of smart, wireless sensor networks for the purposes of Structural Health Monitoring of large scale civil infrastructure. However, the power requirements of such networks are dependent on finite batteries, which limit the effectiveness of such a system. The use of energy harvesters, however, offers a viable and attractive solution to this problem. This paper investigates the use of such energy harvesters not only to power wireless sensor nodes, but to also act in the process as a damage detection tool. The properties and creation of such energy harvesters is detailed in full. The effects of damage on a simply supported reinforced concrete beam are investigated through finite element analysis. The use of the energy harvesters for damage detection is subsequently investigated and the feasibility of using such harvesters is experimentally validated. The simultaneous power of wireless sensor nodes by the harvesters is determined and an energy harvesting circuit is examined in this regard. This paper establishes the basis and viability of using an energy harvesting system for use in this dual role.
  • Publication
    A Review of Road Structure Data in Six European Countries
    The European Union has expanded significantly in recent years. Sustainable trade within the Union leading to economic growth to the benefit of the 'old' and 'new' member states is thus extremely important. The road infrastructure is strategic and vital to such development since an uneven transport infrastructure, in terms of capacity and condition, has the potential to reinforce uneven development trends and hinder economic convergence of old and new member states. Significantly, in the decades since their design and construction, loading conditions have significantly changed for many major highway infrastructure elements/networks due primarily to increased freight volumes and vehicle sizes. This coupled with the gradual deterioration of a significant number of highway structures, due to their age, and the absence of a pan-European assessment framework can be expected to affect the smooth functioning of the infrastructure in its as-built condition, through increased periods of reduced flow due to planned and unplanned interventions for repair/rehabilitation. This paper reports the findings of a survey regarding the current status of the highway infrastructure elements in six countries within the European Union as reported by the owners/operators. The countries surveyed include a cross section of ‘existing’ older countries and ‘new’ accession countries. The current situations for bridges, culverts, tunnels and retaining walls are reported along with their potential replacement costs. The findings act as a departure point for further studies in support of a Centralized and/or Synchronised EU approach to Infrastructure Maintenance Management. Information in the form presented in this paper is central to any future decision making frameworks in terms of trade route choice and operations, monetary investment, optimized maintenance, management and rehabilitation of the built infrastructure and the economic integration of the newly joined member states.
  • Publication
    Analysis of End-Stop Parameters on the Performance of Heaving Point Absorber Wave Energy Convertors
    Wave energy converters (WEC) have the potential to generate a sizeable proportion of Ireland’s energy needs. Although there has been a great deal of research into WEC technology, no commercial devices exist at this time. One reason for this, has been underestimating the forces involved in the marine environment, and thus under designing components, especially power take off (PTO) systems. End stops are a crucial component of all moving body converters, which have rigid connections to PTOs. They are designed to protect the PTO mechanism by restricting the allowable travel distance. End stops, although vital components of WEC technology limit energy generation and thus must be taken into account in initial design. In this paper, a torus shaped point absorber moving against a monopile is numerically modelled in operational conditions using combined potential flow boundary element method and modified Morison's equation viscous drag. Two torus geometries are modelled, varying the radius and draft. The effect of various end-stop parameters on PTO forces and average annual energy generation are analysed. These parameters being; WEC travel distance, end stop distance and stiffness. Two separate Irish sites are analysed, a high energy site off the west coast and a medium energy site off the south coast. This paper aids WEC development by describing the performance effects of end stop design.
  • Publication
    Experimental Detection of Sudden Stiffness Change in a Structural System Employing Laser Doppler Vibrometry
    (Erredi Grafiche Editoriali, 2012-06-20) ; ; ;
    Sudden changes in the stiffness of a structure are often indicators of structural damage. Detection of such sudden stiffness change from the vibrations of structures is important for Structural Health Monitoring (SHM) and damage detection. Non-contact measurement of these vibrations is a quick and efficient way for successful detection of sudden stiffness change of a structure. In this paper, we demonstrate the capability of Laser Doppler Vibrometry to detect sudden stiffness change in a Single Degree Of Freedom (SDOF) oscillator within a laboratory environment. The dynamic response of the SDOF system was measured using a Polytec RSV-150 Remote Sensing Vibrometer. This instrument employs Laser Doppler Vibrometry for measuring dynamic response. Additionally, the vibration response of the SDOF system was measured through a MicroStrain G-Link Wireless Accelerometer mounted on the SDOF system. The stiffness of the SDOF system was experimentally determined through calibrated linear springs. The sudden change of stiffness was simulated by introducing the failure of a spring at a certain instant in time during a given period of forced vibration. The forced vibration on the SDOF system was in the form of a white noise input. The sudden change in stiffness was successfully detected through the measurements using Laser Doppler Vibrometry. This detection from optically obtained data was compared with a detection using data obtained from the wireless accelerometer. The potential of this technique is deemed important for a wide range of applications. The method is observed to be particularly suitable for rapid damage detection and health monitoring of structures under a model-free condition or where information related to the structure is not sufficient.
  • Publication
    The Dynamics Effects of Marine Growth on a Point Absorbing Wave Energy Converter
    (University of Malta, 2016-01-01) ; ;
    Wave energy convertors have the potential to generate a sizeable proportion of Ireland’s energy needs. Such platforms will be susceptible to bio fouling over their design life with marine growth capable of altering the hydrodynamic loading. Marine growth causes member effective diameter, mass, drag coefficients, force and hydrodynamic added mass to increase. In this paper, marine growth of various thickness and surface roughness is numerically modelled on two torus shaped point absorbers moving against a monopile in operational conditions using combined potential flow boundary element method and Morison equation viscous drag. Marine growth thickness and surface roughness have a notable effect on the platform hydrodynamic forces. However, the power matrix remains generally similar. The smaller WEC shows the greatest change with a 20 % increase in draft and 5 % increase in power.
  • Publication
    Inspection of Cycleways with DataCycle - Preliminary Results
    (Irish Transport Research Network, 2017-08-29) ; ; ;
    This paper presents the first inspection results using DataCycle, a first maintenance management system for cycleways in Ireland. DataCycle provides a system of inspection and assessment of cycleways, along with an inspection manual. As a first application of DataCycle, the inspection method and assessment is applied to two different cycling routes in Cork, Ireland. The first route is the Passage West to Rochestown cycle route, which has been developed along an old disused rail line and is in an area where cycling and walking for both leisure and commuting is possible. The second route is the Cork City to Ballincollig Cycleway. This is the main cyclist commuter route between Ballincollig and the city centre. It covers a distance of 6.4km. The cycle route is comprised of a segregated roadside cycleway and a shared footpath and cycle route in parts. The assessments compare and contrast these two distinct routes and demonstrates how a Cycleway Management System(CMS) in the form of DataCycle can be beneficial to managing this asset in a targeted manner. The ease of use, ability to align with existing maintenance management systems and the possibility of upscaling the system is highlighted. The results present typical outputs for some of the routes inspected implementing the cycleway management system with suggested intervention options. The work demonstrates how the developed system can be easily implemented for cycleways and encourages the use of such centralised maintenance system for cycleways throughout the country. A substantial inspection database for cycling facilities should allow for implementation of asset management methodologies, including cross-asset management formats.
  • Publication
    The dynamic effects of marine growth on a tension moored floating wind turbine
    (Taylor & Francis, 2016-01-01) ; ;
    As the offshore wind industry moves to water depths greater that 50m floating platforms will become the only cost effective solution for mounting turbines. Such platforms will be susceptible to bio fouling over their design life with marine growth capable of altering the hydrodynamic loading. Marine growth causes member effective diameter, mass, drag coefficients, force and hydrodynamic added mass to increase. In this paper, marine growth of various thickness and surface roughness is numerically modelled on a tension moored floating wind turbine under survival conditions using combined potential flow boundary element method and Morison equation viscous drag. The influence of time variant Reynolds number dependant drag coefficients is compared against time invariant drag coefficients. Marine growth thickness and surface roughness have a notable effect on the platform hydrodynamic forces. Surge, pitch motions, and nacelle accelerations decrease as surface roughness increases. Maximum tendon forces increase and minimum tendon forces decrease. This increases the probability of a catastrophic tendon snap or slack event. The authors calculate the increase in displacement required to avoid this loss in tension. Detailed limits on the quantity of marine growth are suggested by the authors, above which the platform must be cleaned. The time invariant drag coefficient method has been found to give sufficiently consistent results to the time variant Reynolds number drag coefficient method
  • Publication
    Damage Assessment of the Built Infrastructure using Smartphones
    (University College Dublin, 2018-08-30) ; ; ;
    The use of image-processing and machine-learning algorithms for road condition monitoring has attracted considerable interest in recent years. This surge in popularity has been propelled by advances in camera technology and the emergence of state-of-the-art deep learning techniques which have allowed inspectors to obtain high-quality imagery on a consistent basis, and then use efficient techniques to recognise road defects with credibility. A wide variety of road defect detection techniques have been proposed, however, the influence that different image acquisition devices have on the accuracy of defect detection has not been studied despite being a key component. The use of smartphone cameras as an inspection tool is of particular interest as they have become ubiquitous in recent times and the built-in cameras have progressed significantly. These cameras are now capable of producing perfectly acceptable images, yet they are still not well compared against established benchmarks. In this paper, the qualities of smartphones are explored and compared against a dedicated DSLR (Digital Single-Lens Reflex) camera. An experiment was designed that involved capturing video footage of a road surface using a smartphone (Samsung Galaxy S7) and a dedicated imaging device (Canon 600D DRSL). A deep learning based crack detection method was applied to imagery from the smartphone and the DRSL cameras and the performances levels were subsequently compared. The results indicate that smartphones are a viable, low-cost method for executing quick assessments of the road integrity. The evaluation of smartphone cameras also addresses the ongoing uncertainty around the level of performance that can be achieved using cheaper sensors for quantitative purposes. Such findings provide reassurance for inspectors wishing to use their smartphones for simple monitoring tasks.
  • Publication
    Guidelines and Recommendations from COST TU 1406
    Asset management depends on well-defined rules and standards for general application. Research results often represent the state of science in specific sections of specific cases. Standardization needs a downgrade of scientific work towards generally applicable specifications. This often leads to irritation in the scientific community fearing that their most interesting results are not specifically appreciated. This conflict makes standardization sometimes difficult. COST action TU1406 is devoted to harmonizing the state of science and technology and to bring all involved disciplines into the process. The results produced are of value for a number of standards on ISO, CEN and National level. This represents another difficulty, namely, to find the right place in any of the organizations and to identify the most suitable technical committee and code. This contribution reports on the experiences made with various committees and the results achieved. It soon became clear that specific parameters for bridge assessment cannot be standardized because they are too specific for a small sector. The way out is formulating the principles how to define them, to make a framework under which the detail results can be applied, and to define the interfaces to other necessary disciplines. Sustainability as a headline was found to be suitable and TC59 of ISO was the committee of choice. Frameworks set in ISO55000 (asset management) and ISO31000 (risk management framework) are successfully addressed. A final draft of ISO 21929-2 is to be expected by early 2019.
  • Publication
    Effects of increasing design traffic load on performance and life-cycle cost of bridges
    (CRC Press - Taylor & Francis Group, 2016-06-07) ; ; ;
    Due to the onerous and expensive nature of preventative and essential maintenance of existing bridge infrastructure, it is prudent to look into methods of improving life-cycle safety and cost of newly constructed bridges at the design phase. In an effort to achieve economy in material quantities and initial cost, the structural capacity of these bridges is often at the required minimum target level. This paper investigates the effects that increased design traffic loading have on the initial construction cost and whether that could be balanced by a reduced requirement for financial intervention in the mid to later stages of the bridge’s design-life. This is achieved by conducting a life-cycle performance and cost assessment on a reinforced concrete slab bridge that is designed to increasing standard traffic loads.