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- PublicationImpact factors on medium span bridges due to multiple vehicle presence(2002-06-20)
; ; ; The Dynamic Amplification Factor for Bridges is of major concern in both their design and assessment. Research to date has focused on the single truck event. However, in many bridges the critical loading case is that of multiple truck presence on the deck. To accurately determine the dynamic amplification factor it is necessary to examine the effects of multiple trucks traversing a bridge. Experiments in Slovenia were carried out to examine the dynamic amplification factor for single and two truck events. Numerical models were constructed and validated from these experiments. These models were then used to compare the dynamic amplification factors produced from both single and multiple trucks crossing the bridge at various speeds. Important conclusions are drawn for bridge design and assessment purposes.76 - PublicationPredicting Tunneling-Induced Ground MovementCost-effective and permissible tunneling can occur only if ground movement prediction is refined to accommodate changes in both the urban environment and tunneling technology. As cities age, tunnels are being installed closer to existing structures and in increasingly complicated belowground conditions. The reality of stacked tunnels, abandoned facilities, and more extensive use of underground space raises the question of whether relationships derived for single open-shield tunnels in free-field conditions can adequately predict ground movement for modern tunneling techniques with more complicated site conditions. Traditional empirical methods to predict maximum surface settlements and the percentage of lost ground for paired tunnels of the new Austrian tunneling method (NATM) in noncohesive soils are evaluated. Predictive data are compared with field measurements for grouted and nongrouted sections. Results showed that the estimated maximum settlement values of an NATM tunnel were highly similar to those of an open shield tunnel for both the grouted and ungrouted sections, although in some cases the Gaussian shape significantly underestimated the depth of the settlement trough in the outer 30% to 40%. Grouting substantially altered the amount of settlement. The average percentage of volume of lost ground with grouting was 1.6%, whereas the value was 5.2% where no grouting occurred. The empirical methods typically generated a fairly reasonable set of responses for an NATM tunnel.
1066 - PublicationCOST 345 - Procedures Required for the Assessment of Highway Structures, Numerical Techniques for Safety and Serviceability Assessment. Report of Working Groups 4 and 5(European Commission, 2004-09-01)
; ; ; ; ; ; ; This document treats the following aspects of the assessment of existing highway structures: Levels of assessment: Five levels of assessment are recommended varying from simple but conservative to complex but accurate. Uncertainty modelling: An integrated approach to traffic loading, structure condition and structural response is described. Load modelling: There can be considerable unused capacity in highway structures that are not subjected to the full design levels of traffic loading. This can be calculated from traffic weight statistics obtained from a weigh-in-motion system. Modelling materials for assessment: The processes are reviewed by which material properties in existing structures can be estimated. Structural response modelling: The types of analysis appropriate to the five recommended levels of assessment are proposed. Target reliability levels: The levels of reliability considered appropriate for highway structure assessment are discussed. Reliability analysis: The available procedures for full reliability analysis of highway structures are reviewed. All of these topics are covered in detail in the following chapters. It is not possible in a report of this nature to provide sufficient details for an engineer to use all of the methods by reading this re- port alone. The report aims to provide sufficient information for engineers and network managers and authorities to choose the appropriate methodology for assessing their structures. It also aims to inform Engineers charged with assessment about some of the procedures available. It is sincerely hoped that this report will contribute to the continued safety and serviceability of the land transport fixed assets in Europe and elsewhere.125 - PublicationExperimental Testing of a Moving Force Identification Bridge Weigh-in-Motion AlgorithmBridge weigh-in-motion systems are based on the measurement of strain on a bridge and the use of the measurements to estimate the static weights of passing traffic loads. Traditionally, commercial systems employ a static algorithm and use the bridge influence line to infer static axle weights. This paper describes the experimental testing of an algorithm based on moving force identification theory. In this approach the bridge is dynamically modeled using the finite element method and an eigenvalue reduction technique is employed to reduce the dimension of the system. The inverse problem of finding the applied forces from measured responses is then formulated as a least squares problem with Tikhonov regularization. The optimal regularization parameter is solved using the L-curve method. Finally, the static axle loads, impact factors and truck frequencies are obtained from a complete time history of the identified moving forces.
871Scopus© Citations 61 - PublicationExamples of building response to excavation and tunneling(2008-12-16)
; ; ; Monitoring of ground movements around tunnels and excavations on the Washington Metro led to development of procedures for assessing ground loss or movements at the boundaries of the excavation or tunnel and the distribution of movements through the soil mass to the ground surface and to adjacent structures (Cording and Hansmire, 1975, O’Rourke and Cording, 1974). As the field investigations progressed in Washington, instrumentation and observations were concentrated on the effect of ground movements on structures. (Boscardin and Cording, 1989). More recently, a research program consisting of numerical and model studies correlated with field observations was conducted to assess the relation of building distortion and damage to excavation-induced ground movements. This paper provides examples of building damage and distortion resulting from excavation or tunneling and evaluates the behavior of the buildings using methods developed in previous studies. The buildings are on shallow foundations in U.S.cities. Most are masonry bearing wall structures built in the 1800s or early 1900s.1846 - PublicationA Regularised Solution to the Bridge Weigh in Motion EquationsThe traditional approach to Bridge Weigh-in-Motion (WIM) developed by Moses, gives good accuracy for estimating gross vehicle weights but is less accurate for individual axle weights. In this paper, Tikhonov regularisation is applied to the original Moses’ equations to reduce some of the inaccuracies inherent within the algorithm. The optimal regularisation parameter is calculated using the L-curve criterion. The new regularised solution is numerically tested using simulations of moving vehicles on a bridge. Results show that the regularised solution performs significantly better than the original approach of Moses and is insensitive to road surface roughness.
1250 - PublicationThe use of wavelets on the response of a beam to a calibrated vehicle for damage detectionThe monitoring of the dynamic properties of a structure as a tool to detect structural damage has been prevalent for some time. The fundamental theory behind this branch of non-destructive testing is that, if a crack was present in a structure it results in a localised loss in stiffness, which leads to a change in the modal properties of the structure. However, while it is reasonably easy to diagnose that a structure has suffered damage, the more challenging problem is to identify its location and severity. In recent years the wavelet transform has been used to locate discontinuities in measurements that could be associated to structural damage. This paper highlights the potential for using the wavelet technique to analyse the response of a beam to the passage of a moving load.
111 - PublicationEU FP6 - ARCHES Deliverable D10: Recommendations on dynamic amplification allowance(FEHRL, 2009-08-01)
; ; ; ; ; The ARCHES (Assessment and Rehabilitation of Central European Highway Structures) project (2006-09) involved partners from Belgium, Croatia, Czech Republic, Ireland, Italy, Poland, Slovenia, Spain, Switzerland and The Netherlands. The overall goal of the project is to reduce any gaps in the standard of highway infrastructure between Central and Eastern European Countries, particularly New Member States and the rest of the EU. Deliverable D10 is within WP2: optimise the use of existing infrastructure through better safety assessment and monitoring procedures which will avoid interventions, i.e., avoid unnecessary replacing or improving structures that are in fact perfectly safe. In particular, D10 provides a more realistic site-specific dynamic allowance for traffic loading than those genral values recommended in bridge codes.Correct evaluation of the behaviour of highway bridges under heavy traffic loading is extremely important both for the enhancement of design techniques, and also for the assessment of existing infrastructure. It is widely accepted that shortfalls exist in the determination of the traffic load which the bridge may be required to support during its expected lifetime due to inadequate consideration of amongst other factors, the dynamic interaction between the bridge structure and the heavy vehicles crossing it. Since it is the overall objective of this deliverable to combine lifetime static load effect values, with realistic dynamic amplification factors (to obtain an overall total lifetime load effect) there are two distinct parts:1) The calculation of bridge static load effect due to site-specific traffic flow, which is discussed in subtask 2.1.1 (Deliverable D08) along with the resultant assessment of bridge lifetime static load effect, and the selection of those loading events that are deemed critical (statically).Examples on how to determine these bridge traffic load models using Weigh-In-Motion (WIM) data and their configuration when using data from Central European countries are provided in subtask 2.1.1 on bridge traffic load monitoring. This subtask has also compared results between data from Western and Central European countries.2) Deliverable D10 focuses on the assessment of the levels of dynamic interaction occurring between a bridge and its associated vehicular traffic. This analysis incorporates a review of those recommendations given in current design/assessment codes for dynamic allowance.Then, the procedure to obtain a site-specific dynamic amplification factor using theoretical simulations and available experimental data is described. Some specific issues concerning the dynamic allowance associated to: (a) deteriorated bridges; (b) pre-existing bridge vibrations; (c) maximum total effects developing in sections different from midspan, (d) the existence of a bump prior to the bridge, or (e) critical loading cases such as cranes, are also discussed. Finally,general recommendations on dynamic allowance are provided.164 - PublicationEU FP6 - ARCHES Deliverable D08: Recommendations on the use of results of monitoring on bridge safety assessment and maintenance(6th EU FP, 2009-08-31)
; ; ; ; ; ; The ARCHES, which is the Specific Targeted Research Project, was planned in response to the European Commission’s call for proposals 3B, addressing Topic 2.6 ‘Design and manufacture of new construction concepts’ of objective ‘Sustainable Surface Transport’ under the Thematic priority 1.6 ‘Sustainable Development, Global Change and Ecosystems’ of the GROWTH part of the Sixth Framework Programme. The contract was signed by the Commission on the 25th of October 2006. Project commencement date was the 1st of September 2006 and the duration of the project is 36 months.184 - PublicationFactors affecting traffic-generated vibrations on structures and the masonry minaret of Little Hagia Sophia(2010-09-02)
; ; ; Increasingly buildings and their occupants are negatively impacted by traffic–induced vibrations. The continuous application of vibrations is particularly detrimental for historic masonry buildings and for very modern structures constructed of strong and light materials. Population and land development trends indicate greater proximity of traffic flow near buildings in coming years. This paper outlines the factors influencing the frequency content and the magnitude of vibrations on nearby structures in an attempt to enable local communities and their designers to be more proactive in vibration mitigation. Using these described factors, the paper assesses the effects of traffic-induced vibrations on a portion of a monumental masonry building: the minaret of Little Hagia Sophia Mosque (former Byzantine Church of the Saints Sergius and Bacchus) based on adjacent railway field measurements.912 - PublicationModeling same-direction two-lane traffic for bridge loadingMany highway bridges carry traffic in two same-direction lanes, and modeling the traffic loading on such bridges has been the subject of numerous studies. Different assumptions have been used to model multiple-presence loading events, particularly those featuring one truck in each lane. Using a database of weigh-in-motion measurements collected at two European sites for over 1 million trucks, this paper examines the relationships between adjacent vehicles in both lanes in terms of vehicle weights, speeds and inter-vehicle gaps. It is shown that there are various patterns of correlation, some of which are significant for bridge loading. A novel approach to the Monte Carlo simulation of such traffic is presented which is relatively simple to apply. This is a form of smoothed bootstrap in which kernel functions are used to add randomness to measured traffic scenarios. It is shown that it gives a better fit to the measured data than models which assume no correlation. Results are presented from long-run simulations of traffic using the different models and these show that correlation may account for an increase of up to 8% in lifetime maximum loading.
1438Scopus© Citations 86 - PublicationA Review of Road Structure Data in Six European CountriesThe 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.
769 - PublicationOpen minded and open access: introducing NeoBiota, a new peer-reviewed journal of biological invasions(Pensoft Publishers, 2011-08-11)
; ; ; ; The Editorial presents the focus, scope, policies, and the inaugural issue of NeoBiota, a new open access peer-reviewed journal of biological invasions. The new journal NeoBiota is a continuation of the former NEOBIOTA publication series. The journal will deal with all aspects of invasion biology and impose no restrictions on manuscript size neither on use of color. NeoBiota implies an XML-based editorial workflow and several cutting-edge innovations in publishing and dissemination, such as semantic markup of and enhancements to published texts, data publication, and extensive cross-linking within the journal and to external sources.153 - PublicationEvaluating the benefits of Octree-based indexing for LiDAR data(American Society for Photogrammetry & Remote Sensing, 2012)
; ; ; In recent years the geospatial domain has seen a significant increase in the availability of very large three dimensional (3D) point datasets. These datasets originate from a variety of sources, such as for example Light Detection and Ranging (LiDAR) or meteorological weather recordings. Increasingly, a desire within the geospatial community has been expressed to exploit these types of 3D point data in a meaningful engineering context that goes beyond mere visualization. However, current Spatial Information Systems (SISs) provide only limited support for vast 3D point datasets. Even those systems that advertise their support for in-built 3D data types provide very limited functionality to manipulate such data types. In particular, an effective means of indexing large 3D point datasets is yet missing, however it is crucial for effective analysis. Next to the large size of 3D point datasets they may also be information rich, for example they may contain color information or some other associated semantic. This paper presents an alternative spatial indexing technique, which is based on an octree data structure. We show that it outperforms R-tree index, while being able to group 3D points based on their attribute values at the same time. This paper presents an evaluation employing this octree spatial indexing technique and successfully highlights its advantages for sparse as well as uniformly distributed data on the basis of an extensive LiDAR dataset.1028 - PublicationA wavelet-based damage detection algorithm based on bridge acceleration response to a vehiclePrevious research based on theoretical simulations has shown the potential of the wavelet transform to detect damage in a beam by analysing the time-deflection response due to a constant moving load. However, its application to identify damage from the response of a bridge to a vehicle raises a number of questions. Firstly, it may be difficult to record the difference in the deflection signal between a healthy and a slightly damaged structure to the required level of accuracy and high scanning frequencies in the field. Secondly, the bridge is going to have a road profile and it will be loaded by a sprung vehicle and time-varying forces rather than a constant load. Therefore, an algorithm based on a plot of wavelet coefficients versus time to detect damage (a singularity in the plot) appears to be very sensitive to noise. This paper addresses these questions by: (a) using the acceleration signal, instead of the deflection signal, (b) employing a vehicle-bridge finite element interaction model, and (c) developing a novel wavelet-based approach using wavelet energy content at each bridge section, which proves to be more sensitive to damage than a wavelet coefficient line plot at a given scale as employed by others.
1855Scopus© Citations 185 - PublicationLiquid interactions with porous media and the fate of toxic materials(Maths in Industry, 2012-04-20)
; ; ; ; Toxic liquid chemicals released into the environment may pose an immediate risk to human health through contact or related vapour hazards. However, they can also interact with surfaces and remain in situ, potentially presenting a subsequent hazard. To improve understanding of the fate of these materials in different environments, the study group investigated interactions between liquid droplets and porous media across a range of different time scales.195 - PublicationPortable Bridge WIM Data Collection Strategy for Secondary Roads(2012-06)
; ; ; A common method of collecting traffic loading data across a large road network is to use a network of permanent pavement-based WIM systems. An alternative is to use one or more portable Bridge Weigh-In-Motion systems which are moved periodically between bridges on the network. To make optimum use of such a system, a suitable data collection strategy is needed to choose locations for the system. This paper describes a number of possible strategies which the authors have investigated for the National Roads Authority in Ireland. The different strategies are examined and their advantages and disadvantages compared. Their effectiveness at detecting a heavy loading event is also investigated and the preferred approach is identified.381 - PublicationTheoretical testing of an empirical mode decomposition damage-detection approach using a spatial vehicle-bridge interaction modelEmpirical mode decomposition (EMD) is used to detect and locate damage in a bridge using its acceleration response to the crossing of a vehicle. EMD is a technique that converts the measured signal into a number of basic functions that make up the original signal. These functions are obtained purely from the original signal in a sequential procedure, where lower order basic functions contain a range of high frequency components of the signal and higher order basic functions contain the low frequency components. Damage is identified through a distinctive peak in the decomposed signal resulting from applying EMD. Recent studies have shown the potential of this tool to detect single and multiple damages when using the response of a one-dimensional beam model to the crossing of a constant load. In this paper, the technique is further developed using simulations from a quarter-car vehicle-bridge dynamic interaction finite element model. The vehicle model is composed of mass elements, which represent the tyre and body masses, and stiffness and damping elements, which represent tyre and suspension systems. The bridge deck is modelled using plate elements with typical properties found on site and the road profile is generated stochastically from power spectral density functions based on ISO standard guidelines. Different levels of damage are simulated as localised losses of stiffness at random locations within the bridge and a number of longitudinal and transverse locations are used as observation points. The ability of the EMD algorithm to detect damage is analysed for a variety of scenarios including two vehicle configurations (light and heavy), a range of speeds between 5 and 15 m/s, and smooth and rough road surfaces. The influence of the distance from the simulated acceleration points to the damage locations, on the accuracy of the predicted damage, is also discussed.
601Scopus© Citations 3 - PublicationZn, Fe and S isotope fractionation in a large hydrothermal system(Elsevier, 2012-07-01)
; ; ; ; The genesis of hydrothermal ore deposits is of crucial economic importance. This study investigates the extent, causes and consequences of zinc and iron isotope fractionation in a large hydrothermal system at the world-class Navan Zn–Pb orebody, Ireland. Large variations in Zn, Fe and S isotope compositions have been measured in microdrilled sphalerite (ZnS) at the millimetre scale. d66Zn and d56Fe display a well-defined positive correlation and both also correlate with d34S. These relationships represent the combined effects of kinetic Zn and Fe isotope fractionation during sphalerite precipitation, and S isotope variation through mixing of hot, metal-rich hydrothermal fluids and cool, bacteriogenic sulfide-bearing brines. Combined with S isotope data, d56Fe and d66Zn data on mine concentrates confirm that hydrothermal sulfide is a minor component of the overall deposit signature. Our data suggest that incoming pulses of metal-rich hydrothermal fluid triggered sulfide mineralisation, and that rapid precipitation of sphalerite from hydrothermal fluids will lead to strong kinetic fractionation of Zn and Fe isotopes at very short time and length scales, thereby limiting the use of Fe and Zn isotopes as exploration tools within deposits, but revealing the possibility of detecting new deposits from isotopically heavy Zn–Fe geochemical halos.1373Scopus© Citations 116 - PublicationExtension of semi-analytical approach to determine natural frequencies and mode shapes of multi-span orthotropic bridge deckThis paper extends a single equation, semi-analytical approach for three-span bridges to multispan ones for the rapid and precise determination of natural frequencies and natural mode shapes of an orthotropic, multi-span plate. This method can be used to study the dynamic interaction between bridges and vehicles. It is based on the modal superposition method taking into account intermodal coupling to determine natural frequencies and mode shapes of a bridge deck. In this paper, a four- and a five-span orthotropic roadway bridge decks are compared in the first 10 modes with a finite element method analysis using ANSYS software. This simplified implementation matches numerical modeling within 2% in all cases. The paper verifies that applicability of single formula approach as a simpler alternative to finite element modeling.
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