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Znidaric, Ales
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Znidaric, Ales
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Znidaric, Ales
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Now showing 1 - 10 of 11
- 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 - PublicationCharacteristic dynamic traffic load effects in bridges(Elsevier, 2009-07)
; ; ; ; When formulating an approach to assess bridge traffic loading with allowance for Vehicle-Bridge Interaction (VBI), a trade-off is necessary between the limited accuracy and computational demands of numerical models and the limited time periods for which experimental data is available. Numerical modelling can simulate sufficient numbers of loading scenarios to determine characteristic total load effects, including an allowance for VBI. However, simulating VBI for years of traffic is computationally expensive, often excessively so. Furthermore, there are a great many uncertainties associated with numerical models such as the road surface profile and the model parameter values (e.g., spring stiffnesses) for the heavy vehicle fleet. On site measurement of total load effect, including the influence of VBI, overcomes many of these uncertainties as measurements are the result of actual loading scenarios as they occur on the bridge. However, it is often impractical to monitor bridges for extended periods of time which raises questions about the accuracy of calculated characteristic load effects. Soft Load Testing, as opposed to Proof Load or Diagnostic Load Testing, is the direct measurement of load effects on bridges subject to random traffic. This paper considers the influence of measurement periods on the accuracy of soft load testing predictions of characteristic load effects, including VBI, for bridges with two lanes of opposing traffic. It concludes that, even for relatively short time periods, the estimates are reasonably accurate and tend to be conservative. Provided the data is representative, Soft Load Testing is shown to be a useful tool for calculating characteristic total load effect.1310Scopus© Citations 56 - PublicationRecommendations on dynamic amplification allowanceThe 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.
346 - PublicationCritical speed for the dynamics of truck events on bridges with a smooth road surface(Elsevier, 2010-05-24)
; ; ; ; ; Simple numerical models of point loads are used to represent single and multiple vehicle events on two-lane bridges with a good road profile. While such models are insufficiently complex to calculate dynamic amplification accurately, they are presented here to provide an understanding of the influence of speed and distance between vehicles on the bridge dynamic response. Critical combinations of speed as a function of main bridge natural frequency and meeting point of two vehicles travelling in opposite directions are identified. It is proposed that such simple models can be used to estimate the pattern of critical speeds versus dynamic amplification for heavy trucks on a bridge with a relatively smooth surface. The crossing of a three-dimensional spring-dashpot truck is simulated over a bridge plate model to test this hypothesis for a range of road roughness. Further validation is carried out using the site-specific mean pattern associated to field measurements due to the passage of a truck population. The latter is found to be closely resembled by the theoretical pattern derived from simple point load models.1574Scopus© Citations 22 - PublicationProcedures for the assessment of highway structures(Institution of Civil Engineers / Thomas Telford Publishing, 2005-02)
; ; ; ; Bridges, earth retaining walls and buried structures make up a substantial proportion of the fixed assets of the land based transportation infrastructure within Europe. Little work has been done on the development of documents covering the assessment of highway structures compared to the design of new structures. This paper describes an approach to assessment developed through working groups 4 and 5 of the European COST (Co-Operation in Science and Technology) Action 345, ‘Procedures required for assessing highway structures’. This Action was supported by the European Commission and involved experts from 16 European countries. The ICE Trust fund has supported a study of a road bridge in Vienna to demonstrate the applicability and potential benefits of the approach developed through COST 345. The approach is similar to that used in the UK in that there are five levels of assessment of increasing complexity and reliability, but there are a number of differences. This paper describes the approach developed through COST 345 with a view of opening the debate on the need for a code of practice for assessment that facilitates the use of site-specific loading.1490Scopus© Citations 21 - PublicationDirect measurement of dynamics in road bridges using a bridge weigh-in-motion system(Technika. Vilnius Gediminas Technical University, 2013-12)
; ; ; A method is presented of measuring a bridge’s characteristic allowance for dynamic interaction in the form of Assessment Dynamic Ratio. Using a Bridge Weigh-in-Motion system, measurements were taken at a bridge in Slovenia over 58 days. From the total observed traffic population, 5-axle trucks were extracted and studied. The Bridge Weigh-in-Motion system inferred the static weights of the trucks, giving each measured event’s dynamic increment of load. Theoretical simulations were carried out using a 3-dimensional vehicle model coupled with a bridge plate model, simulating a traffic population similar to the population measured at the site. These theoretical simulations varied those properties of the 5-axle fleet that influence the dynamic response; simulating multiple sets of total (dynamic + static) responses for a single measured static strain response. Extrapolating the results of these theoretical simulations to a 50-year Assessment Dynamic Ratio gives similar results to those obtained by extrapolating the data measured using the Bridge Weigh-in-Motion system. A study of the effect of Bridge Weigh-in-Motion system errors on the predictions of Assessment Dynamic Ratio is conducted, identifying a trend in the Bridge Weigh-in-Motion calculations of maximum static response. The result of this bias is in turn quantified in the context of predicting characteristic maximum total load effect.452Scopus© Citations 10 - 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 - PublicationExperimental determination of dynamic allowance for traffic loading in bridges(Transportation Research Board, 2010)
; ; ; Bridge codes adopt values for dynamic allowance in traffic load models that are necessarily conservative to cover for an entire range of bridges with different mechanical characteristics, boundary conditions, and the large number of uncertainties associated to the vehicle-bridge interaction problem. A further level of conservatism occurs due to the independent manner in which the governing static load and the corresponding allowance for dynamics are specified. In particular, certain bridges are not susceptible to high levels of vehicle-bridge interaction when loaded by a critically heavy vehicle or a critical combination of vehicles. Recent advances in Bridge Weigh-In-Motion technology allow not only to collect information on the weights, spacings and speeds of the traffic loads traversing a bridge, but also to separate the maximum static strain from the total measured strain using a filtering procedure. In this paper, maximum static and total load effects are collected and analysed for three different sites as part of the European project ARCHES (6th RTD framework programme). Bridge measurements are used to discuss the dynamics of the most frequent truck classes and the entire traffic sample. The measurements reveal a decrease in percentage increment in dynamics and a reduction on the variability of the dynamic increment as the static load effect increases. This phenomenon can be of particular relevance in the assessment of the dynamics of extreme loading cases.348 - PublicationRecommendations for Dynamic Allowance in Bridge AssessmentThis paper summarises the developments in the dynamic response of bridges to traffic loading based on a large amount of simulations and field tests carried out within the 6th EU framework ARCHES (2006-2009). When assessing the total traffic load effect on a bridge, there is a number of alternatives to characterise the associated dynamic component depending on the information available to the engineer. The simplest approach is to adopt the conservative values provided in bridge codes covering for many uncertainties. Nevertheless, if bridge drawings, bridge properties, updated weigh-in-motion data and road profile were known, then validated vehicle-bridge finite element interaction models can be used to reduce these uncertainties. Dynamic allowance can also be experimentally derived from measured total load effects using modern bridge weigh-in-motion technology. Guidelines are provided on how to obtain a site-specific value of dynamic allowance, both numerically and experimentally.
512 - 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