Now showing 1 - 10 of 14
  • 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.
      173
  • Publication
    Laboratory based experimental investigation of patch based piezoelectric energy harvesters for civil infrastructure
    (University College Dublin, 2018-08-30) ; ;
    Vibration energy harvesting technology applications for civil infrastructure has received significant interest in recent times. This is due to the advantages that are associated with power independent, output only energy harvesters which have the potential to act as either the power supply to low-power wireless sensors or as power independent sensors. Studies into the deployment of such harvesters with civil infrastructure applications have shown a potential range of applications ranging including high-rise buildings, pipelines, bridge infrastructure and wind turbine structures. While there can be immense cost associated with validation of energy harvesters through full-scale testing with civil infrastructure, laboratory based validation provides an inexpensive method of validating specific vibration energy harvesting devices with individual structures. By applying available datasets of vibrational response of civil infrastructure to the device using the shaker unit, the individual devices may be tested for realistic excitation conditions without any scaling of the structures vibrational response being required. This paper considers the use of laboratory based testing procedures for the experimental validation of patch based energy harvesters. The theoretical performance of the harvester for a model bridge undergoing train loadings is determined and the performance using measured datasets from full scale testing for train bridge interaction is similarly shown. An experimental setup is created to experimentally test the energy harvesters and the results of the experimental results versus the theoretical expectations are compared. This paper helps further establish the importance of laboratory based testing for vibration energy harvesters with civil infrastructure applications.
      207
  • Publication
    Energy harvesting from train-induced response in bridges
    The integration of large infrastructure with energy-harvesting systems is a growing field with potentially new and important applications. The possibility of energy harvesting from ambient vibration of bridges is a new field in this regard. This paper investigates the feasibility of energy harvesting for a number of trains considering their passage over a bridge. The power that can be derived from an energy-harvesting device due to a train crossing a bridge at different speeds is compared against typical demands of small wireless devices and is found to be adequate for powering such devices. These estimates of harvested energy also relate to the individual signatures of trains. In this work, the modeled dynamic responses of a bridge traversed by trains are compared against full-scale experimental analysis of train-bridge interactions. A potential application in structural health monitoring (SHM) using energy harvesting has also been demonstrated and compared with laboratory experimental data. Consistent and monotonic damage calibration curves have been constructed using estimated harvested energy.
      583Scopus© Citations 82
  • Publication
    Dynamic response signatures of a scaled model platform for floating wind turbines in an ocean wave basin
    Understanding of dynamic behaviour of offshore wind floating substructures is extremely important in relation to design, operation, maintenance and management of floating wind farms. This paper presents assessment of nonlinear signatures of dynamic responses of a scaled tension leg platform (TLP) in a wave tank exposed to different regular wave conditions and sea states characterised by the Bretschneider, the Pierson-Moskowitz, and the JONSWAP spectra. Dynamic responses of the TLP was monitored at different locations using load cells, camera based motion recognition system, and Laser Doppler Vibrometer. The analysis of variability of the TLP responses and statistical quantification of their linearity or nonlinearity, as non-destructive means of structural monitoring from output only condition, remains a challenging problem. In this study, the Delay Vector Variance (DVV) method is used to statistically study the degree of nonlinearity of measured response signals from TLP. DVV is observed to create a marker estimating the degree to which a change in signal nonlinearity reflects real time behaviour of the structure, and also to establish the sensitivity of the instruments employed to these changes. The findings can be helpful in establishing monitoring strategies and control strategies for undesirable levels or types of dynamic response, and can help better estimating changes in system characteristics over the life-cycle of the structure.
      262Scopus© Citations 31
  • Publication
    Mitigating the structural vibrations of wind turbines using tuned liquid column damper considering soil-structure interaction
    This paper considers the potential of using a Tuned Liquid Column Damper (TLCD) to reduce structural vibrations of a wind turbine tower. The effect of TLCD on wind turbine towers, including the soil-structure interactions for a monopile foundation was modelled theoretically and scaled laboratory experiments were carried out to validate these results. The tower of the turbine is represented as a Euler beam with a set of springs at the boundary to simulate the soil-structure interaction. TLCD design was carried out using such a model and the reduction in tower vibrations due to the deployment of TLCD was then examined for various loading conditions in the frequency and the time domain. The efficiency of TLCDs for reducing structural vibrations was investigated for tuned and detuned conditions. The response of a small-scale model was simulated along with that of a full-scale turbine and parametric studies around the variations of inputs related to uncertainties were performed. Experiments were carried out on a scaled model turbine to examine the effectiveness of the TLCD. The practicalities of installing a TLCD in a full-scale turbine were examined.
      566Scopus© Citations 55
  • Publication
    Psychometric properties and responsiveness to change of 15- and 28- item versions of the SCORE: A family assessment questionnaire
    The SCORE (Systemic Clinical Outcome and Routine Evaluation) is a 40-item questionnaire for completion by family members 12 years and older to assess outcome in systemic therapy. This study aimed to investigate psychometric properties of two short versions of the SCORE and their responsiveness to therapeutic change. Data were collected at 19 centers from 701 families at baseline and from 433 of these 3–5 months later. Results confirmed the three-factor structure (strengths, difficulties, and communication ) of the 15- and 28-item versions of the SCORE. Both instruments had good internal consistency and test–retest reliability. They also showed construct and criterion validity, correlating with measures of parent, child, and family adjustment, and discriminating between clinical and non clinical cases. Total and factor scales of the SCORE-15 and -28 were responsive to change over 3–5 mont hs of therapy. The SCORE-15 and SCORE-28 are brief psychometrically robust family assessment instruments which may be used to evaluate systemic therapy.
      1169Scopus© Citations 43
  • Publication
    Horizontal loading effects of fresh concrete on precast arches
    This paper investigates the horizontal effect of fresh concrete on precast arches. A number of different models of horizontal pressure of fresh concrete are considered in this regard. The effects of fresh concrete on a precast arch are represented as a ratio of maximum normal stress from horizontal action of fresh concrete to the normal stress induced by the self-weight of the precast concrete arch. A parameter study on a number of geometric and operational variables was carried out. The implications of this horizontal loading from fresh concrete are discussed within the context of the potential financial effects.
      458
  • Publication
    Modelling and testing of a historic steel suspension footbridge in Ireland
    Daly’s Bridge is a historic steel suspension footbridge in Ireland, known locally as the ‘Shaky Bridge’ for its noticeable movement under pedestrian loading. While there is concern regarding the performance of the structure, testing or modelling have not been carried out till date and inadequate information exist in relation to carrying out such analyses. In this paper, Daly’s bridge is instrumented and tested for the first time and a model of the bridge is established and improved in the process. Apart from ambient vibration, excitation from traversing pedestrians and cyclists is considered. Video analysis of dynamic deflection, a wavelet packet based technique using acceleration responses and dynamic measurements from a cheap smartphone accelerometer application are used to identify and compare the natural frequency of the bridge. The work contributes to the evidence base of full-scale measurements of instrumenting and analysing responses of aging pedestrian bridges highlighting the complexity, challenges, opportunities and limitations related to varied levels of information available from disparate sources . The study also highlights the need of investigating to what extent cheap sensors can be successfully used as compared to their more expensive and sophisticated counterpart.
      560Scopus© Citations 14
  • Publication
    Energy Harvesting Techniques for Health Monitoring and Indicators for Control of a Damaged Pipe Structure
    (Korea Science, 2018-03-25) ; ; ;
    Applications of energy harvesting from mechanical vibrations is becoming popular but the full potential of such applications is yet to be explored. This paper addresses this issue by considering an application of energy harvesting for the dual objective of serving as an indicator of structural health monitoring (SHM) and extent of control. Variation of harvested energy from an undamaged baseline is employed for this purpose and the concept is illustrated by implementing it for active vibrations of a pipe structure. Theoretical and experimental analyses are carried out to determine the energy harvesting potential from undamaged and damaged conditions. The use of energy harvesting as indicator for control is subsequently investigated, considering the effect of the introduction of a tuned mass damper (TMD). It is found that energy harvesting can be used for the detection and monitoring of the location and magnitude of damage occurring within a pipe structure. Additionally, the harvested energy acts as an indicator of the extent of reduction of vibration of pipes when a TMD is attached. This paper extends the range of applications of energy harvesting devices for the monitoring of built infrastructure and illustrates the vast potential of energy harvesters as smart sensors.
    Scopus© Citations 19  247
  • Publication
    Validation of a 28-item version of the Systemic Clinical Outcome and Routine Evaluation in an Irish context: The SCORE-28
    This paper describes the development, in an Irish context, of a 3-factor, 28-item version the Systemic Clinical Outcome and Routine Evaluation (SCORE) questionnaire for assessing progress in family therapy. The 40-item version of the SCORE was administered to over 700 Irish participants including non-clinical adolescents and young adults, families attending family therapy, and parents of young people with physical and intellectual disabilities and cystic fibrosis. For validation purposes, data were also collected using brief measures of family and personal adjustment. A 28-item version of the SCORE (the SCORE-28) containing three factor scales that assess family strengths, difficulties and communication was identified through exploratory principal components analysis. Confirmatory factor analysis showed that the factor structure of the SCORE-28 was stable. The SCORE-28 and its 3 factor scales were shown to have excellent internal consistency reliability, satisfactory test-retest reliability, and construct validity. The SCORE-28 scales correlated highly with the General Functioning Scale of the Family Assessment Device, and moderately with the Global Assessment of Relational Functioning Scale, the Kansas Marital and Parenting Satisfaction Scales, the Satisfaction with Life Scale, the Mental Health Inventory – 5, and the total problems scale of the Strengths and Difficulties Questionnaire. Correlational analyses also showed the SCORE-28 scales were not strongly associated with demographic characteristics or social desirability response set. The SCORE-28 may routinely be administered to literate family members over 12 years before and after family therapy to evaluate therapy outcome.
      1214Scopus© Citations 38