http://hdl.handle.net/10197/7934 Fri, 03 Nov 2017 17:59:33 GMT 2017-11-03T17:59:33Z http://researchrepository.ucd.ie:80/bitstream/id/23531/ http://hdl.handle.net/10197/7934 http://hdl.handle.net/10197/9002 Methodologies for Crack Initiation in Welded Joints Applied to Inspection Planning Zou, Guang; Banisoleiman, Kian; González, Arturo Crack initiation and propagation threatens structural integrity of welded joints and normally inspections are assigned based on crack propagation models. However, the approach based on crack propagation models may not be applicable for some high-quality welded joints, because the initial flaws in them may be so small that it may take long time for the flaws to develop into a detectable size. This raises a concern regarding the inspection planning of high-quality welded joins, as there is no generally acceptable approach for modeling the whole fatigue process that includes the crack initiation period. In order to address the issue, this paper reviews treatment methods for crack initiation period and initial crack size in crack propagation models applied to inspection planning. Generally, there are four approaches, by: 1) Neglecting the crack initiation period and fitting a probabilistic distribution for initial crack size based on statistical data; 2) Extrapolating the crack propagation stage to a very small fictitious initial crack size, so that the whole fatigue process can be modeled by crack propagation models; 3) Assuming a fixed detectable initial crack size and fitting a probabilistic distribution for crack initiation time based on specimen tests; and, 4) Modeling the crack initiation and propagation stage separately using small crack growth theories and Paris law or similar models. The conclusion is that in view of trade-off between accuracy and computation efforts, calibration of a small fictitious initial crack size to S-N curves is the most efficient approach. Tue, 01 Nov 2016 00:00:00 GMT http://hdl.handle.net/10197/9002 2016-11-01T00:00:00Z http://hdl.handle.net/10197/8765 Uncertainty quantification and calibration of a modified fracture mechanics model for reliability-based inspection planning Zou, Guang; Banisoleiman, Kian; González, Arturo Efficient inspection and maintenance are important means to enhance fatigue reliability of engineering structures, but they can only be achieved efficiently with the aid of accurate pre-diction of fatigue crack initiation and growth until fracture. The influence of crack initiation on fatigue life has received a significant amount of attention in the literature, although its im-pact on the inspection plan is not generally addressed. Current practice in the prediction of fatigue life is the use of S-N models at the design stage and Fracture Mechanics (FM) models in service. On the one hand, S-N models are relatively easy to apply given that they directly relate fatigue stress amplitude to number of cycles of failure, however, they are difficult to extrapolate outside the test conditions employed to define the S-N curves. On the other hand, FM models like the Paris propagation law give measurable fatigue damage accumulation in terms of crack growth and have some ability to extrapolate results outside the test conditions, but they can only be a total fatigue life model if the initial crack size was known given that they do not address the crack initiation period. Furthermore, FM models generally introduce large uncertainties in parameters that are often difficult to measure such as initial crack size, crack growth rate, threshold value for stress intensity factor range, etc. This paper proposes a modified FM model that predicts the time to failure allowing for crack initiation period. The main novelty of the modified FM model is the calibration using S-N data (i.e., inclusive of crack initiation period) for an established criterion in fatigue life and reliability level. Sources of uncertainty associated to the model are quantified in probabilistic terms. The modified FM model can then be applied to reliability-based inspection planning. An illustrative example is performed on a typical detail of ship structure, where the optimum inspection plan derived from the proposed model is compared to recommendations by existing FM models. Results demonstrate to what extent is the optimum inspection plan influenced by the crack initiation period. The modified model is shown to be a reliable tool for both fatigue design and fatigue management of inspection and maintenance intervals.  12th International Conference on Structural Safety & Reliability (ICOSSAR 2017), Vienna, Austria, August, 2017 Thu, 10 Aug 2017 00:00:00 GMT http://hdl.handle.net/10197/8765 2017-08-10T00:00:00Z http://hdl.handle.net/10197/8759 Development of probabilistic fracture mechanics method for fatigue life prediction based on EIFS concept Zou, Guang; Banisoleiman, Kian; González, Arturo A problem with fracture mechanics (FM) based fatigue analysis is that reliable information on initial crack/flaw size is often unavailable. Also, FM method cannot be applied directly to welded joints with relatively small initial flaws and long crack initiation life. This paper proposes a novel probabilistic FM method based on the equivalent initial flaw size (EIFS) concept. The initial crack size is substituted with EIFS to take both the crack initiation and propagation life into account. Three methods are tested to obtain mean value of EIFS: calibrating to S-N curve, Kitagawa-Takahashi (KT) diagram and fitting to test data. The obtained EIFSs are evaluated by comparing the predicted fatigue lives and crack evolutions with S-N curve and test crack evolution data. The suggested procedure is to derive the mean value of EIFS from S-N curve and the coefficient of variation from KT diagram. 36th International Conference on Ocean, Offshore and Arctic Engineering (OMAE 2017), Trondheim, Norway, June, 2017 Thu, 01 Jun 2017 00:00:00 GMT http://hdl.handle.net/10197/8759 2017-06-01T00:00:00Z http://hdl.handle.net/10197/8756 Developments in damage assessment by Marie Skłodowska-Curie TRUSS ITN project González, Arturo The growth of cities, the impacts of climate change and the massive cost of providing new infrastructure provide the impetus for TRUSS (Training in Reducing Uncertainty in Structural Safety), a €3.7 million Marie Skłodowska-Curie Action Innovative Training Network project funded by EU's Horizon 2020 programme, which aims to maximize the potential of infrastructure that already exists (http://trussitn.eu). For that purpose, TRUSS brings together an international, inter-sectoral and multidisciplinary collaboration between five academic and eleven industry institutions from five European countries. The project covers rail and road infrastructure, buildings and energy and marine infrastructure. This paper reports progress in fields such as advanced sensor-based structural health monitoring solutions - unmanned aerial vehicles, optical backscatter reflectometry, monitoring sensors mounted on vehicles, ... - and innovative algorithms for structural designs and short- and long-term assessments of buildings, bridges, pavements, ships, ship unloaders, nuclear components and wind turbine towers that will support infrastructure operators and owners in managing their assets. 12th International Conference on Damage Assessment of Structures (DAMAS 2017), Kitakyushu, Japan, July, 2017 Sat, 01 Jul 2017 00:00:00 GMT http://hdl.handle.net/10197/8756 2017-07-01T00:00:00Z http://hdl.handle.net/10197/8755 Developments in damage assessment by Marie Skłodowska-Curie TRUSS ITN project González, Arturo The growth of cities, the impacts of climate change and the massive cost of providing new infrastructure provide the impetus for TRUSS (Training in Reducing Uncertainty in Structural Safety), a €3.7 million Marie Skłodowska-Curie Action Innovative Training Network project funded by EU's Horizon 2020 programme, which aims to maximize the potential of infrastructure that already exists (http://trussitn.eu). For that purpose, TRUSS brings together an international, inter-sectoral and multidisciplinary collaboration between five academic and eleven industry institutions from five European countries. The project covers rail and road infrastructure, buildings and energy and marine infrastructure. This paper reports progress in fields such as advanced sensor-based structural health monitoring solutions - unmanned aerial vehicles, optical backscatter reflectometry, monitoring sensors mounted on vehicles, ... - and innovative algorithms for structural designs and short- and long-term assessments of buildings, bridges, pavements, ships, ship unloaders, nuclear components and wind turbine towers that will support infrastructure operators and owners in managing their assets. Thu, 01 Jun 2017 00:00:00 GMT http://hdl.handle.net/10197/8755 2017-06-01T00:00:00Z http://hdl.handle.net/10197/8754 Damage detection using curvatures obtained from vehicle measurements O'Brien, Eugene J.; Martinez, Daniel; Malekjafarian, Abdollah; Sevillano, Enrique This paper describes a new procedure for bridge damage identification through drive-by monitoring. Instantaneous curvature (IC) is presented as a means to determine a local loss of stiffness in a bridge through measurements collected from a passing instrumented vehicle. Moving reference curvature (MRC) is compared with IC as a damage detection tool. It is assumed that absolute displacements on the bridge can be measured by the vehicle. The bridge is represented by a finite element (FE) model. A Half-car model is used to represent the passing vehicle. Damage is represented as a local loss of stiffness in different parts of the bridge. 1% random noise and no noise environments are considered to evaluate the effectiveness of the method. A generic road surface profile is also assumed. Numerical simulations show that the local damage can be detected using IC if the deflection responses can be measured with sufficient accuracy. Damage quantification can be obtained from MRC. Sat, 01 Jul 2017 00:00:00 GMT http://hdl.handle.net/10197/8754 2017-07-01T00:00:00Z http://hdl.handle.net/10197/8753 Reliability assessment of braided BFRP reinforcement for concrete structures Antonopoulou, Sofia; McNally, Ciaran In recent years the long term durability of reinforced concrete structures has become a major concern. The effect of harsh loading conditions and aggressive environmental factors can lead to corrosion of reinforcing steel in civil engineering applications. This in turn leads to undesired repairs, additional costs and shorter service lives. Advanced composite materials, such as Basalt Fibre Reinforced Polymer (BFRP), have the capacity to significantly address this problem. These materials have enhanced physical properties such as higher mechanical and corrosion resistance, and have the potential to replace traditional steel rebars as tension reinforcement in concrete. There are however limitations that prevent their use on a larger scale, and lack of ductility is the most significant. Braiding techniques could provide the required performance benefits related to the additional ductility and flexibility needed, as well as enhancing the bond between FRP and concrete. If this is achieved, it has the potential to prevent a brittle failure and successfully meet strength, reliability and cost demands. This study focuses on the basics of materials characterization and reliability analysis of internal BFRP reinforcement for concrete structures towards design optimization for structural reliability over their service life.  27th European Safety and Reliability Conference (ESREL 2017), Portoro¿, Slovenia, June, 2017 Thu, 25 May 2017 00:00:00 GMT http://hdl.handle.net/10197/8753 2017-05-25T00:00:00Z http://hdl.handle.net/10197/8752 Comparative study on Bayesian updating of bridge safety model Heitner, Barbara; Yalamas, Thierry; O'Brien, Eugene J.; Décatoire, Rodrigue; Schoefs, Franck Probabilistic assessment of ageing bridges has become an important research area as it interests not only researchers but investors, municipalities and even governments. In this paper a simple bridge model is presented in a probabilistic context. A comparative study is carried out involving damage indicators and Bayesian updating. Bayesian updating is a powerful tool, which has been used in various research areas. However, using it for approximating the safety level of a bridge is challenging due to the various sources of uncertainties that may affect the performance of a measurement based damage indicator. The effects of different factors involved in the updating are examined in this paper and compared. 27th annual European Safety and Reliability Conference (ESREL 2017), Portoroz, Slovenia, June, 2017 Thu, 25 May 2017 00:00:00 GMT http://hdl.handle.net/10197/8752 2017-05-25T00:00:00Z http://hdl.handle.net/10197/8751 The effect of angles and distance on image-based, three-dimensional re-constructions Chen, Siyuan; Laefer, Debra F.; Byrne, Jonathan; Natanzi, Atteyeh S. This paper introduces a three-dimensional reconstruction experiment based on a physical laboratory-based experiment on a brick wall. Using controlled shooting distances and angles, different images sets were captured and processed with a structure from motion based technique, which can reconstruct 3D models based on multi-view, two-dimensional (2D) images. Those 2D geometries are shown to generate significant deformations within the resulting point cloud, especially where there were large angles (with respect the camera position and the wall's normal direction) and at close distances to the wall's surface. This paper demonstrates that by overlapping different flawed image sets, the deformation problem can be minimised.  27th annual European Safety and Reliability Conference (ESREL 2017), Portoroz, Slovenia, June, 2017 Thu, 25 May 2017 00:00:00 GMT http://hdl.handle.net/10197/8751 2017-05-25T00:00:00Z http://hdl.handle.net/10197/8750 Pavement Condition Measurement at High Velocity using a TSD Malekjafarian, Abdollah; Martinez, Daniel; O'Brien, Eugene J. The aim of this paper is to present the latest developments in the use of an instrumented vehicle called the Traffic Speed Deflectometer (TSD). A large axle load is applied to the pavement under the TSD . The deflection caused by this axle load is measured using several Doppler lasers. In the first step, the velocity of the deflection of the pavement is measured which can be shown to be proportional to the slope of the de- formed profile . The pavement deflection is calculated in the second step using an integration model . A Wi n- kler model is used to simulate the pavement behavio ur under the axle load and the TSD is represented as a half-car model . The TSD is shown to be an effective tool for pavement damage detection. 27th annual European Safety and Reliability Conference (ESREL 2017), Portoroz, Slovenia, June, 2017 Thu, 25 May 2017 00:00:00 GMT http://hdl.handle.net/10197/8750 2017-05-25T00:00:00Z http://hdl.handle.net/10197/8749 Reliability-based inspection planning in view of both crack initiation and propagation Zou, Guang; Banisoleiman, Kian; González, Arturo Fatigue cracks pose threats to the integrity of welded structures and thus need to be addressed in the whole service lives of structures. In-service inspections are important means to decease the probability of failure due to uncertainties that cannot be accounted for in the design stage. To help schedule inspection actions, the decline curve of reliability index with time needs to be known. A predictive tool is normally developed based on crack propagation models neglecting the crack initiation stage, which leads to conservative predictions for fatigue life. Inspection plans built on those predictions are far from optimal, especially for welds with relatively long crack initiation life. This paper proposes to use a fracture mechanics based reliabil-ity analysis method that takes the crack initiation stage into account via the concept of Time-To-Crack-Initiation (TTCI). The optimum inspection plan for a fatigue prone ship structural component is derived by the new approach and compared to the commonly-used method that only considers crack propagation life. Two inspection planning approaches are tested to investigate the influence of incorporating crack initiation period: (i) target reliability approach and, (ii) equidistant inspection times approach. With each planning ap-proach, two inspection methods are adopted: close visual and magnetic particle inspection. The paper con-cludes with recommendations on the inspection method and planning approach to adopt while considering and without considering the crack initiation stage. 27th annual European Safety and Reliability Conference (ESREL 2017), Portoroz, Slovenia, June, 2017 Thu, 25 May 2017 00:00:00 GMT http://hdl.handle.net/10197/8749 2017-05-25T00:00:00Z http://hdl.handle.net/10197/8748 Field characterization of location-specific dynamic amplification factors towards fatigue calculations in ship unloaders Milana, Giulia; Banisoleiman, Kian; González, Arturo This paper highlights the impact of dynamic amplification factors in remaining fatigue life assessment of ship unloaders. In practice, the widely accepted procedure for these structures is to carry out a fatigue life assessment envisages: (1) carrying out static analysis, (2) taking into account dynamics via the application of dynamic amplification factors, and (3) applying Miner's rule. This factor, provided by the standard, is applied to the structure as a whole without considering the vibration of each structural member individually. This paper characterizes the dynamic behavior of each element using location-based dynamic amplification factors estimated from measurements. This caters for a more accurate assessment of the structure, whilst maintaining the simplicity of the standard procedure. 27th annual European Safety and Reliability Conference (ESREL 2017), Portoroz, Slovenia, June, 2017 Thu, 25 May 2017 00:00:00 GMT http://hdl.handle.net/10197/8748 2017-05-25T00:00:00Z http://hdl.handle.net/10197/8747 Parametric analysis of modelling properties governing the seismic response of free-standing spent fuel racks Gonzalez Merino, Alberto; Costas de la Peña, Luis; González, Arturo Spent fuel racks are steel structures designed to store the spent fuel assemblies removed from the nuclear power reactor. In order to maximize the storage capacity of the pool, rack units are spaced by only a few centimeters setting up a matrix shape to fit in the spent fuel pool with a minimum clearance. Rack units rest in free-standing conditions submerged in water at 12 m depth. During a seismic event, racks undergo large displacements namely sliding, rocking, twisting and turning. Furthermore, the response of a unit is influenced by the others due to the so-called 'water coupling effect'. An accurate estimation of their response is essential to achieve a safe pool layout and a reliable structural design. The dynamic analysis of such a rack system deals with highly nonlinear behavior, a transient dynamic response and a fluid-structure interaction problem. A transient analysis with direct integration of the equation of motion throughout the whole earthquake duration becomes therefore unavoidable. An ad-hoc methodology based on the finite element method takes advantage of dynamic contact elements and implements the hydrodynamic mass concept. The latter has traditionally been accepted as a cost-effective approach to replace the water effect by an equivalent added mass. However, some dispersion of results still remains. This paper carries out a parametric analysis of the key modelling properties for a simple two-rack system. This technique examines the behavior of the main transient outputs as a modelling parameter is systematically varied. The modelling parameters under study are the mesh discretization, the rack-to-pool and fuel-to-cell contact stiffness, the flexural rigidity of the fuel assembly and the gaps existing between the fuel assembly and the storage cell. Its influence is highlighted on outputs as maximal and minimal relative displacements, maximal vertical force on support and CPU time. These numerical results provide a source of insight into the general behavior of the rack systems and an effective tool to propose a reliable modeling and meshing. The trade-off between outputs and computational cost and is also discussed. 27th annual European Safety and Reliability Conference (ESREL 2017), Portoroz, Slovenia, June, 2017 Thu, 25 May 2017 00:00:00 GMT http://hdl.handle.net/10197/8747 2017-05-25T00:00:00Z http://hdl.handle.net/10197/8561 A New Damage Indicator for Drive-by Monitoring using Instantaneous Curvature O'Brien, Eugene J.; Martinez, Daniel; Malekjafarian, Abdollah; Pape, Torill Drive-by monitoring has enhanced the possibilities for bridge damage detection, with the potential to deliver a bridge rating in the time it takes an instrumented vehicle to pass overhead. This paper outlines the importance of Instantaneous Curvature (IC) as an indicator of local damage. For the IC calculation, bridge deflections are measured from the vehicle before and after the occurrence of damage, so that a comparison between the two situations can be made. Differences in curvature are clearly visible in numerical simulations, especially at the damage location. A Finite Element model of a simply supported bridge subject to a crossing vehicle is modelled dynamically. In this paper, the Curvature Ratio (CR) is proposed as the damage indicator, defined as the ratio of IC in the current bridge to IC in the corresponding healthy bridge. Road profile and random noise in the simulated measurements are considered to represent realistic conditions. Simulations in MATLAB demonstrate that CR is an effective indicator in most of the analysis cases. Austroads Bridge Conference 2017 (ABC 2017), Pullman Melbourne Albert Park, Melbourne, Australia, 3-6 April 2017 Thu, 06 Apr 2017 00:00:00 GMT http://hdl.handle.net/10197/8561 2017-04-06T00:00:00Z http://hdl.handle.net/10197/8382 Damage Detection by Drive-by Monitoring Using the Vertical Displacements of a Bridge Martinez, Daniel; O'Brien, Eugene J.; Sevillano, Enrique Drive-by monitoring has received increasing attention in recent years, as it has great potential useful for Structural Health Monitoring (SHM) applications. Although direct instrumentation of civil infrastructures has been demonstrated to be a way of detecting damage, it is also a very expensive method as it requires data acquisition, storage and transmission facilities on each bridge. Drive-by constitutes an alternative that allows the monitoring of a bridge without the necessity of installing sensors on it. In this numerical study, the vertical displacements of the bridge are used for damage detection purposes. The goal of this paper is to describe a model that can reproduce the vertical displacements of the bridge when a simulated vehicle is driving through and show how these displacements change with damage. Vertical displacements are calculated before and after damage, so that the sensitivity of the data to bridge damage can be determined. A finite element (FE) model of a simply supported beam interacting with a moving half car is used in this study. Damage is represented as a loss of stiffness in several parts of the bridge. Vertical displacements are generated at a moving reference for healthy and damaged states, corresponding to vehicle location on the bridge. Two options are explored, the first axle and the second one, as the locations to fix the simulated sensor on the vehicle. Sixth International Conference on Structural Engineering, Mechanics and Computation (SEMC 2016), Cape Town, South Africa, 5 to 7 September 2016 Wed, 07 Sep 2016 00:00:00 GMT http://hdl.handle.net/10197/8382 2016-09-07T00:00:00Z http://hdl.handle.net/10197/8289 Development of Braided Basalt FRP Rebar for Reinforcement of Concrete Structures Antonopoulou, Sofia; McNally, Ciaran; Byrne, Greg In recent years, the development and use of Fibre Reinforced Polymer composite materials in infrastructure have gained increasing attention worldwide. More specifically, natural mineral fibres such as basalt are currently being developed and are showing promising properties. Within an appropriate polymer matrix, their use as reinforcement in concrete structures offers performance benefits related to their environmentally friendly and non-corrodible nature. In particular, BFRPs have the potential to replace conventional internal steel rebar and thus, to be the next generation material in concrete reinforcement applications. A detailed literature review indicates that a careful selection of the appropriate manufacture technique and design methodology are required in order to prevent brittle failure on a concrete structure reinforced with FRP composite material. This paper reports on how to use the additional helical reinforcement and the braid configuration in order to increase strength, structural ductility and long term durability. Moreover, this study outlines the development of an analytical numerical model to predict the longitudinal elastic modulus of braided composites, as well as its validation by comparison of the results with available data from the literature. 8th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering (CICE 2016), Hong Kong, China, 14-16 December 2016 Fri, 16 Dec 2016 00:00:00 GMT http://hdl.handle.net/10197/8289 2016-12-16T00:00:00Z http://hdl.handle.net/10197/8250 Strength assessment of in-situ concrete for the evaluation of structural capacity: State of the art Sourav, Shah Nur Alam; Salam Al-Sabah, Abd; McNally, Ciaran With more emphasis on reusing and extending the life of structures, it often becomes necessary to assess the capacity of existing concrete structures. One major component of this assessment relates to the concrete strength. Most reliable results are obtained by taking cores. However, such assessment is ideally made with a combination of destructive and nondestructive testing to minimise damage to the structure. The currently available methods for assessing in-situ concrete strength of the existing structures can be broadly divided into two groups. One group of tests is completely non-destructive. The other group is partially destructive where limited damage to the surface is caused by the tests. For the strength evaluation of existing concrete, methods such as surface hardness test, ultrasonic pulse velocity test, penetration resistance test and maturity test fall under the non-destructive category. Partially destructive tests include pull out test, CAPO test, pull off test and break off test. This paper critically evaluates and analyses the applicability and limitations of the methods used for evaluating concrete strength in existing structures. Most methods for strength evaluation are found to measure a certain property such as elasticity, density, tensile strength or hardness of concrete and then relate the measured value to compressive strength. Studies on these methods show a wide variation in the correlations between estimated and predicted compressive strength. Partially destructive methods are noted to provide correlations with good consistency between estimated and predicted compressive strength. Civil Engineering Research in Ireland Conference (CERI 2016), Galway, Ireland, 29-30 August 2016 Tue, 30 Aug 2016 00:00:00 GMT http://hdl.handle.net/10197/8250 2016-08-30T00:00:00Z http://hdl.handle.net/10197/8152 State of Technology Review of Civilian UAVs Chen, Siyuan; Laefer, Debra F.; Mangina, Eleni Background: Unmanned Aerial Vehicle (UAV) technology has exploded in recent years. Presently UAVs are beginning to be major in roads into geographical mapping, site inspection, agriculture, and search and rescue. Methods: This paper reviewed patents and papers worldwide related to both hardware and software for the construction and deployment of UAVs and is intended to provide a snapshot of currently available UAV technologies, as well as to identify recent trends and future opportunities in affiliated hardware and software. Results: Basic components related to self-designed units are explained (e.g. platform selection, autopilot control comparison and sensor selection), and current applications and research areas are discussed. Since autonomous navigation is a key technology in UAV applications, concepts about this are also explained. Conclusions: Both in the self-designed and commercial markets, UAV components are becoming modularized. By following a standard components list, it is no longer difficult to make a customised UAV. In this way, commercial products are becoming cheaper and more standardized in their performance. Current limitations of UAVs has also become more readily detectible. Extending the flight time, improving autonomous navigation abilities, and enriching the payload capacity will be the future research focus to address these limitations. Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/10197/8152 2016-01-01T00:00:00Z http://hdl.handle.net/10197/8048 Methodologies for Crack Initiation in Welded Joints Applied to Inspection Planning Zou, Guang; Banisoleiman, Kian; González, Arturo Over the past decades, crack propagation has been extensively studied by researchers around the word. The approach based on crack propagation models have been widely used in inspection planning. This approach has the advantage that it gives measurable fatigue damage accumulation in terms of crack propagation with time and thus crack propagation models can be updated with inspection results. However, a prerequisite for using crack propagation models in inspection planning is that parameters such as initial crack size, crack growth rate, geometry function, etc. are known.  Among those parameters, initial crack size, depending on welding quality, material and the environment, is associated with the most uncertainties because of sampling and measuring problems. Another prerequisite for using crack propagation models in inspection planning is that crack initiation period can be assumed to be negligible. Both prerequisites are challenged nowadays as manufacturing and welding techniques have been improved. Some high-quality welded joins have been proven free from detectable size of flaws and the crack initiation period can account for a large part of the whole fatigue life. This gives rise to big difficulty for inspection planning of high-quality welded joins, as there is no generally acceptable approach for modelling the whole fatigue process that includes crack initiation period. Compared to as-welded joints, reliable inspection planning is more crucial for high-quality welded joins, as they are generally designed to withstand a larger stress range. In addition, they may have shorter time for inspection as crack initiation time account for a large part of fatigue life, with a shorter crack propagation period to failure due to higher stress range. To address this problem for high-quality welded joints, a robust model accounting for the whole fatigue process needs to be developed. The core issue is how the crack initiation period can be modelled and added to the crack propagation time. To help identify this issue, this paper reviews treatment methods for crack initiation period and initial crack size in crack propagation models applied to inspection planning. Generally there are four approaches, by: 1) Neglecting the crack initiation period and fitting a probabilistic distribution for initial crack size based on statistical data, e.g. Weibull distribution or lognormal distribution; 2) Extrapolating the crack propagation stage to a very small fictitious initial crack size, so that the whole fatigue process can be modelled by crack propagation models; 3) Assuming a fixed detectable initial crack size and fitting a probabilistic distribution for crack initiation time based on specimen tests; 4) Modelling the crack initiation and propagation stage separately using small crack growth theories and Paris law or similar models. Conclusion is that in view of trade-off between accuracy and computation efforts, calibration of a small fictitious initial crack size to S-N curves is the most efficient approach. ICRSS 2016: 18th International Conference on Reliability and Structural Safety, Venice, Italy, 7-8 November 2016 Tue, 08 Nov 2016 00:00:00 GMT http://hdl.handle.net/10197/8048 2016-11-08T00:00:00Z http://hdl.handle.net/10197/8038 Developing braided FRP reinforcement for concrete structures Antonopoulou, Sofia; McNally, Ciaran; Byrne, Greg In recent years, significant research has been conducted, by both industry and academia, into the optimum development and use of Fibre Reinforced Polymer composite materials in infrastructure. In particular, it is widely recognised that FRPs have the potential to replace conventional internal steel rebars in concrete reinforcement and offer performance benefits related to their advanced properties, such as corrosion resistance, high tensile strength etc.A review of the available literature indicates that brittle behaviour of FRP can significantly decrease the expected ultimate load capacity and, thus have a negative effect on structure¿s long term durability. However, selecting braiding as manufacture technique and enhancing flexural capacity and shear strength through additional helical reinforcement, could provide structure with the additional ductility needed to prevent a brittle failure. Furthermore, the impact of deterioration mechanisms, focusing on the interaction between FRP and concrete in a structure, is an aspect for further investigation via laboratory testing and advanced analysis.This study summarises the results of research on structural design and manufacture methods of FRP composite materials by presenting new configuration and types of FRP reinforcement in order to encourage the use of these promising materials in construction industry. Civil Engineering Research in Ireland Conference (CERI 2016), Galway, Ireland, 29-30 August 2016 Tue, 30 Aug 2016 00:00:00 GMT http://hdl.handle.net/10197/8038 2016-08-30T00:00:00Z http://hdl.handle.net/10197/7997 Probabilistic modelling of bridge safety based on damage indicators Heitner, Barbara; O'Brien, Eugene J.; Schoefs, Franck; Yalamas, Thierry; Décatoire, Rodrigue; Leahy, Cathal This paper introduces the various aspects of bridge safety models. It combines the different models of load and resistance involving both deterministic and stochastic variables. The actual safety, i.e. the probability of failure, is calculated using Monte Carlo simulation and accounting for localized damage of the bridge. A possible damage indicator is also presented in the paper and the usefulness of updating the developed bridge safety model, with regards to the damage indicator, is examined. The 9th International Conference on Bridges in Danube Basin: New Trenda in Bridge Engineering and Efficient Solution for Large and Medium Bridges 2016, Žilina, Slovakia, 30 September - 1 October 2016 Sat, 01 Oct 2016 00:00:00 GMT http://hdl.handle.net/10197/7997 2016-10-01T00:00:00Z http://hdl.handle.net/10197/7985 Sources of structural failure in ship unloaders Milana, Giulia; Banisoleiman, Kian; Gonzalez, Arturo This paper reviews the most common causes of failure in ship unloaders. The structural forms employed in the design of ship unloaders and the characteristics of the loads acting on these structures are introduced first. Then, typical failures including overloading, joint failure, cable breaking, corrosion and fatigue failure amongst others, are described. Fatigue failure is discussed in further detail. When assessing a ship unloader for fatigue, it is necessary to define the fatigue demand and the fatigue strength capacity of those structural details under investigation. The latter experiences stress cycles that accumulate over time until reaching a limit that leads to cracking. Loads and stresses need to be monitored to describe those cycles, and critical locations must be checked to prevent a catastrophic failure. 26th European Safety and Reliability Conference (ESREL 2016), Glasgow, UK, 25-29 September 2016 Thu, 29 Sep 2016 00:00:00 GMT http://hdl.handle.net/10197/7985 2016-09-29T00:00:00Z http://hdl.handle.net/10197/7970 Evaluation of bridge safety based on Weigh-in-Motion data Heitner, Barbara; O'Brien, Eugene J.; Schoefs, Franck; Yalamas, Thierry; Décatoire, Rodrigue; Leahy, Cathal This paper investigates various concerns, sensitivities of and correlation between the different parameters influencing the load on a bridge and its resistance to that load. The actual safety, i.e. the probability of failure, is calculated by combining the dead load, Weigh-in-Motion data based traffic load and resistance models. The usefulness of updating the developed bridge safety model using damage indicators from a Structural Health Monitoring system is also examined. Civil Engineering Research in Ireland 2016 (CERI2016), National University of Ireland Galway, Ireland, 29-30 August 2016 Tue, 30 Aug 2016 00:00:00 GMT http://hdl.handle.net/10197/7970 2016-08-30T00:00:00Z http://hdl.handle.net/10197/7969 Monitoring the Condition of a Bridge using a Traffic Speed Deflectometer Vehicle Travelling at Highway Speed O'Brien, Eugene J.; Sevillano, Enrique; Martinez, Daniel The Traffic Speed Deflectometer (TSD) is a vehicle incorporating a set of laser Doppler vibrometers on a straight beam to measure the relative velocity between the beam and the pavement surface. This paper describes a numerical study to see if a TSD could be used to detect damage in a bridge. From this measured velocity it is possible to obtain the curvature of the bridge, from whose analysis, it will be demonstrate that information on damage can be extracted. In this paper a Finite Element model is used to simulate the vehicle crossing a single span bridge, for which deflections and curvatures are calculated. From these numerical simulations, it is possible to predict the change in the curvature signal when the bridge is damaged. The method looks promising and it suggests that this drive-by approach is more sensitive to damage than sensors installed on the bridge itself. BCCCE 3rd International Balkans Conference on Challenges of Civil Engineering, Epoka University, Tirana, Albania, 19-21 May 2016 Sat, 21 May 2016 00:00:00 GMT http://hdl.handle.net/10197/7969 2016-05-21T00:00:00Z http://hdl.handle.net/10197/7968 Drive-by Bridge Damage Detection Using Curvatures in Uncertain Environments Martinez, Daniel; O'Brien, Eugene J.; Sevillano, Enrique Considerable effort has been dedicated in recent years to the development of bridge damage detection techniques. Recently, drive-by monitoring has become popular as it allows the bridge to be monitored without installing sensors on it. In this work, the Traffic Speed Deflectometer (TSD), which incorporates a set of laser Doppler sensors on a straight beam to obtain the relative velocity between the vehicle and the pavement surface, is modelled to obtain deflections on the bridge as the vehicle drives. From these deflections it is possible to obtain the curvature of the bridge, from which inferences on damage can be made. However, most of the time, the measurements taken by drive-by sensors are subject to a set of uncertainties or noise that can lead the damage detection procedure to either give false positives or to miss damage. For that reason, an analysis is needed in order to determine if these methods can work properly in uncertain or noisy environments. Moreover, as the road surface roughness affects the dynamic interaction between the vehicle and the bridge, this may also have an effect on the damage predictions. Hence, the goal of this paper is to study the sensitivity of curvature measurements to both the presence of environmental noise and the effect of the road surface roughness. Civil Engineering Research in Ireland Conference (CERI2016), Galway, Ireland, 29-30 August 2016 Tue, 30 Aug 2016 00:00:00 GMT http://hdl.handle.net/10197/7968 2016-08-30T00:00:00Z http://hdl.handle.net/10197/7909 Dynamic analysis of the nonlinear response of high density fuel storage racks Gonzalez Merino, Alberto; Costas de la Peña, Luis; González, Arturo High Density Spent Fuel Storage racks are steel structures designed to hold nuclear spent fuel assemblies removed from the nuclear power reactor. Weighing around 60 tons, they are 5m high free-standing structures resting on the floor of a 12m depth pool and separated by only a few centimetres. Their underwater seismic response is a troubling safety issue, especially after Fukushima nuclear disaster. However, only limited basic guidelines have been provided as regulatory design criteria to date. The racks’ design deals with a very highly nonlinear behaviour, a transient dynamic response and a fluid-structure interaction problem. Industry is currently using available computer-aided finite element analysis software to solve the design problem in a cost-effective manner but some dispersion of results still exists. Hence, the nuclear regulatory authorities are requiring an evaluation of the current uncertainty associated to the assessment of rack displacements, rocking and maximum forces on supports. This paper discusses the main difficulties faced during the seismic analysis and presents an ad-hoc analysis methodology based on the hydrodynamic mass concept which takes advantage of a simplifying thermal analogy. The methodology, implemented in ANSYS FE Mechanical is hereby described for a reduced scale 2-rack model where the coupling effect of water in the dynamic motion of immersed racks is quantified and displacements and forces are provided. Finally, methodology assumptions are discussed and lessons learnt about the behaviour trends are summarized. Civil Engineering Research in Ireland (CERI 2016), Galway, Ireland, 29-30 August 2016 Tue, 30 Aug 2016 00:00:00 GMT http://hdl.handle.net/10197/7909 2016-08-30T00:00:00Z http://hdl.handle.net/10197/7810 Uncertainties in seismic design of free-standing HDSFS Racks Gonzalez Merino, Alberto; Costas de la Peña, Luis; González, Arturo High Density Spent Fuel Storage (HDSFS) racks are structures designed to hold nuclear spent fuel assemblies removed from the nuclear power reactor after having been irradiated. They are used in the first step of the waste management process, during the wet storage. The underwater seismic response of HDSFS racks is a troubling safety issue. Since they are 12 m submerged free standing multi-body structures loaded with radioactive fuel, their design remains as complex as crucial [1] [2]. The design deals with a Fluid-Structure Interaction (FSI) problem, a transient dynamic response and a very highly nonlinear behaviour. Several cost-effective industrial approaches have been used in these calculations to date, but some dispersion of results still exists. Therefore, the regulatory authorities are requiring an evaluation of the uncertainties in the methodology. Equipos Nucleares, S.A. (ENSA) is a worldwide expert in racks design and construction [3] and has recently launched a research project to improve the understanding of the phenomena. The latter is funded by the European Comision1 and aimed to identify, evaluate and reduce the uncertainties involved in the calculations. In this paper, the state of the art and the current sources of uncertainty are discussed. 9th International Youth Nuclear Congress (IYNC 2016), Hangzhou, China, 24-30 July 2016 Sat, 30 Jul 2016 00:00:00 GMT http://hdl.handle.net/10197/7810 2016-07-30T00:00:00Z http://hdl.handle.net/10197/7770 Fatigue Life Assessment Methods: the Case of Ship Unloaders Milana, Giulia; Banisoleiman, Kian; González, Arturo This paper reviews methodologies for fatigue analysis with emphasis on ship unloaders. Maintaining the performance of ship unloaders at a satisfactory level is essential for any port's operation in order to comply with the global demand of shipping and trading. Ship unloaders are subject to alternating operational loadings and to adverse environmental conditions, and as a result, they show a rapid rate of deterioration that makes them susceptible to failure by cumulative damage processes such as corrosion and fatigue. The purpose of this paper is to review key features of the most common methodologies for fatigue analysis and to underline the limitations and uncertainties involved. Finally, developments in reliability-based approaches are suggested for a more accurate fatigue assessment of ship unloaders. 1st International Conference on Natural Hazards & Infrastructure (ICONHIC 2016): Protection, Design and Rehabilitation, Chania, Greece, 28-30 June 2016 Thu, 30 Jun 2016 00:00:00 GMT http://hdl.handle.net/10197/7770 2016-06-30T00:00:00Z http://hdl.handle.net/10197/7768 Instantaneous Curvature in Bridge Damage Detection Sevillano, Enrique; O'Brien, Eugene J.; Martinez, Daniel Among all the Structural Health Monitoring (SHM) recent methods found in literature, drive-by monitoring has demonstrated to be promising for damage detection purposes, particularly in bridges. As curvatures can be derived from displacement measurements taken by this method, they can also be used for damage detection, which has already been successfully demonstrated. This paper describes the use of Instantaneous Curvature (IC) for that purpose. Once the absolute displacements of the bridge are measured, damage location and quantification can be obtained through IC when having a moving reference over a bridge. In this paper, a bridge is represented by a finite element model of a Euler-Bernoulli beam. A Half-Car model of a vehicle is used to represent a Traffic Speed Deflectometer (TSD), a drive-by monitoring vehicle. Damage is represented as a loss of stiffness in different parts of the bridge and 1 % measurement noise is added. A generic road profile is also considered. Healthy and damaged states of the bridge are compared in order to validate the method. Proceedings of the CSHM-6: Structural Health Monitoring of New and Ageing Infrastructure, Queen's University Belfast, Belfast, United Kingdom, 26-27 May 2016 Fri, 27 May 2016 00:00:00 GMT http://hdl.handle.net/10197/7768 2016-05-27T00:00:00Z http://hdl.handle.net/10197/7668 Analysis of Load Test on Composite I-Girder Bridge Huseynov, F.; Brownjohn, J. M. W.; O'Brien, Eugene J.; Hester, David This paper showcases the importance of field testing in efforts to deal with the deteriorating infrastructure. It demonstrates a load test performed on a healthy but aging composite reinforced concrete bridges in Exeter, UK. The bridge girders were instrumented with strain transducers and static strains were recorded while a four-axle, 32 tonne lorry remained stationary in a single lane. The results obtained from the field test were used to calculate transverse load distribution factors (DFs) of the deck structure for each loading case. Additionally, a 3-D finite element model of the bridge was developed and calibrated based on field test data. Similar loading cases were simulated on the analytical model and behaviour of the structure under static loading was studied. It was concluded that the bridge support conditions had changed throughout its service life, which affected the superstructure load distribution characteristics. Finally, DFs obtained from analysis were compared with factors provided in Design Manual for Roads and Bridges Standard Specification for similar type of bridges. Proceedings of the CSHM-6: Structural Health Monitoring of New and Ageing Infrastructure, Queen's University Belfast, Northern Ireland, United Kingdom, 26-27 May 2016 Fri, 27 May 2016 00:00:00 GMT http://hdl.handle.net/10197/7668 2016-05-27T00:00:00Z http://hdl.handle.net/10197/6859 TRUSS: A Marie Skłodowska-Curie Innovative Training Network in the field of Structural Safety González, Arturo TRUSS: A Marie Skłodowska-Curie Innovative Training Network in the field of Structural Safety are a prestigious scheme funded by the European Union which aims to train a new generation of creative, entrepreneurial and innovative Early-Stage Researchers (ESRs), able to face current and future challenges and to convert knowledge and ideas into products and services for economic and social benefit [1]. A total 1161 proposals were evaluated as part of the H2020-MSCA-ITN-2014 call for a success rate of about 10.5%. The School of Civil Engineering in University College Dublin (UCD) is coordinating one of the 121 successful ITN proposals, titled TRUSS (Training in Reducing Uncertainty in Structural Safety, http://TrussITN.eu). TRUSS is a 4 year project with an estimated budget of €3.7 million that started on the 1st January 2015. Near 40% of the total budget is shared amongst Irish beneficiaries. Tue, 14 Jul 2015 00:00:00 GMT http://hdl.handle.net/10197/6859 2015-07-14T00:00:00Z