Digitala Vetenskapliga Arkivet

Endre søk
Begrens søket
66676869707172 3401 - 3450 of 5875
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 3401.
    McGarvey, Terence
    Statens väg- och transportforskningsinstitut, Infrastruktur, INFRA, Drift och underhåll, DOU.
    Barrier separated road type design: accelerated degradation2017Rapport (Annet vitenskapelig)
    Abstract [en]

    To reduce the risk of vehicular head-on collisions, the Swedish Transport Administration (Trafikverket), has been transforming high traffic-volume conventional roads into barrier separated roads. This process has reduced the number of fatalities by around 80 percent.

    However, evidence has shown that barrier separated roads degrade quicker than conventional road types.

    The extent of the problem was quantified by comparing various sets of road surface characteristic data. Comparisons revealed that degradation levels increase by up to 60 percent in the single lane sections of 2+1 type barrier separated roads.

    Vehicle position surveys were carried out and subsequent data analysis confirmed that confinement of vehicle lateral wander is a main cause of the problem. The analysis indicated that in the single lane section of a 2+1 type barrier separated road, vehicle lateral wander reduced by 24 percent for light vehicles and 19 percent for commercial traffic. These figures increased to 44 percent and 39 percent for a 1+1 type barrier separated road.

    Accelerated degradation can be attributed to poor cross-sectional design. The amount of vehicular lateral wander is restricted and results in surface wear and loading being concentrated in narrow tracks along the road section.

    Design improvements are possible but will obviously require higher initial investment expenditure.

    Fulltekst (pdf)
    fulltext
  • 3402.
    McGarvey, Terence
    Statens väg- och transportforskningsinstitut, Infrastruktur, INFRA, Drift och underhåll, DOU.
    Vehicle lateral position depending on road type and lane width: vehicle position surveys carried out on the Swedish road network2016Rapport (Annet vitenskapelig)
    Abstract [en]

    In previous studies of barrier separated road types, it was found that vehicle lane position and the amount of lateral wander varied depending on road type and lane width. These variations will have a direct effect on the rate of surface wear and will influence where stresses and strains are distributed in the pavement structure. In order to determine the extent of these variations, a series of position surveys were carried out on common road types found on the Swedish road network. Twenty-one sets of survey data provided information on over 271,000 vehicles. The data was divided into three groups depending on approximate axle track width. Using the survey data, it was possible to calculate and plot the distribution of lateral position (wheel path), the average position, and the variation of lateral position (lateral wander) for each group. Factors such as lane type, lane width, verge width, total width, and close proximity of guardrail all had some influence on vehicle position and amount of lateral wander. The extent of lateral wander varied quite considerably. Standard deviation values associated with the average position of light vehicles varied between 455 millimetres and 190 millimetres. Commercial traffic values were lower and ranged between 430 millimetres and 140 millimetres. These are large variations and will have a significant effect on road degradation rates. Such variations should be taken into account when planning construction or maintenance work.

    Fulltekst (pdf)
    fulltext
  • 3403.
    McLearnon, Stephen
    et al.
    Trafikverket.
    Jakobsson, Liza
    Trafikverket.
    Persson, Sofia
    Trafikverket.
    Förbereda för ett införande av anläggningar för nykterhetskontroller i vissa hamnar: Redovisning av ett regeringsuppdrag2017Rapport (Annet vitenskapelig)
    Abstract [sv]

    Regeringen har gett Trafikverket i uppdrag att förbereda för införande av anläggningar för nykterhetskontroller i vissa hamnar. Redovisningen ska innehålla förslag på hamnar, där också dialog och samarbete med föreslagna hamnar har inletts. Redovisningen ska också visa på förslag på lösningar, finansieringen och kostnadseffektiviteten av dessa, ansvarsfördelning mellan berörda parter, en tidplan för genomförande och hur upphandling av anläggningar förbereds.

    Fulltekst (pdf)
    fulltext
  • 3404. McVay, M.
    et al.
    Birgisson, Björn
    University of Florida.
    Lee, S.
    Influence of Sample Size, Testing and Pile/Shaft Model Variability on LRFD Resistance Factors2004Inngår i: Geotechnical Special Publication, ISSN 0895-0563, Vol. 2Artikkel i tidsskrift (Fagfellevurdert)
  • 3405. McVay, M
    et al.
    Birgisson, Björn
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Nguyen, T
    Kuo, C
    Uncertainty in LRFD phi, Factors for Driven Prestressed Concrete Piles2002Inngår i: Transportation Research Record, Vol. 1808Artikkel i tidsskrift (Fagfellevurdert)
  • 3406. McVay, M
    et al.
    Ellis, R
    Birgisson, Björn
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Consolazio, G
    Putcha, S
    Lee, S
    Use of LRFD, Cost and Risk: Designing a Drilled-Shaft Load Test Program in Florida Limestone2003Inngår i: Transportation Research Record, Vol. 1849Artikkel i tidsskrift (Fagfellevurdert)
  • 3407.
    Meesmann, Uta
    University of Liège.
    Potential For Growth: New Countries Joining2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The objective of this presentation is to give a brief overview of the structure of the ESRA network and the possibilities to join this initiative. The next edition, in which countries can join, will be launched in October 2018.

    Fulltekst (pdf)
    fulltext
  • 3408.
    Meesmann, Uta
    University of Liège.
    Special Session: Monitoring Road Safety Attitudes & Performance the ESRA Approach2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This session will provide insights on the ESRA approach of monitoring road safety attitudes and safety performance, on a global level. It especially addresses researchers and policy makers who are interested in using representative online surveys in road safety monitoring. Furthermore, potential partners will have the chance to ask questions on participation in the ESRA network.

    ESRA (E-Survey of Road users’ Attitudes) is a global cross-national initiative in currently 38 countries. The aim of the project is to provide scientific support to road safety policy by generating comparable national data on the current road safety situation. Using a uniform sampling method, an identical questionnaire and uniform programming of the questionnaire, allows for full comparability among the countries.

    The objective of this session is to provide an overview on the project: motivation, objectives, methodology, and key results. The different speakers will highlight examples of extracting results on regional, national and thematic level:

    1. Uta Meesmann (ESRA coordinator; Vias institute, Belgium): motivation, objectives, methodology and recent key results on regional level.
    2. Ward Vanlaar (ESRA2 core group partner; TIRF, Canada): comparison of national- and regional results with respect to mobile phone use (Europe, Canada, and USA).
    3. Sangjin Han (ESRA2 core group partner; KOTI, Republic of Korea): comparison of national results of the Republic of Korea with European results (benchmarking).
    4. Gerald Furian (ESRA1_2 core group partner; KfV, Austria): extracting thematic results from ESRA and combining them with external data sources, here exemplified with CARE accident data.
    5. Uta Meesmann (ESRA coordinator; Vias institute, Belgium): brief overview of the structure of the ESRA network and the possibilities to join this initiative (next wave ESRA2 - 2019).

    The session will close with a discussion on using representative online survey in monitoring road safety attitudes and performance. Furthermore, potential new partners will have the chance to ask questions on joining this network.

    Background and motivation: Monitoring road safety attitudes and performance

    Trends in road safety performance and the success of policy measures can be monitored using road safety indicators. Important data sources to assess the road safety situation are accident statistics, road side surveys, and questionnaire surveys. The latter, in particular if they are conducted online, are a relatively inexpensive way to obtain indicators on safety culture and road users’ behaviour, but they rely on self-declared information which might be prone to factors such as social desirability in responses. A main advantage of questionnaire surveys is that they can provide insights into socio-cognitive determinants of behaviour, such as attitudes, perceived social norm, risk perception, or existing habits. Socio-cognitive factors can help to understand the underlying motivations of certain behaviour (e.g. Ajzen, 1991; Rosenstock, 1974; Rogers, 1975; Vanlaar and Yannis, 2006). It is tempting to use such indicators based on questionnaire surveys for benchmarking purposes. However, the results of national surveys are seldom comparable across countries because of differences in the aims, the scope, the methodology, the questions used, or the sample population being surveyed.

    Therefore, the European Commission initiated the European project SARTRE (Social Attitudes to Road Traffic Risk in Europe; homepage: www.attitudes-roadsafety.eu/) in 1991. A common questionnaire and study design was developed and face to face interviews were conducted among a representative sample of the national adult population. Four editions of the SARTRE survey were launched (1991, 1996, 2002, 2010). In the first three editions of the SARTE project, surveys were directed only to car drivers. In the fourth edition, the target group was extended to ‘powered two wheelers’, pedestrians, cyclists and users of public transport (Cestac and Delhomme, 2012). This SARTRE4 survey in 2010, was the last large-scale measurement of social attitudes towards road traffic risk in Europe. Since then, there was a lack of comparable and reliable data on road safety attitudes and behaviour within Europe. Hence, in 2015, the Vias institute (formerly Belgian Road Safety Institute) launched the ESRA initiative (E-Survey of Road users’ Attitudes; homepage: www.esranet.eu).

    Fulltekst (pdf)
    fulltext
  • 3409.
    Meesmann, Uta
    University of Liège.
    The ESRA Survey: Cross National Initiative To Monitor Road Users’ Attitudes And Performence2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In 2015 the Vias institute (formerly Belgian Road Safety Institute), in cooperation with research institutes and road safety organizations from 17 European countries, launched the ESRA initiative (E-Survey of Road users’ Attitudes; homepage: www.esranet.eu). The initiative apparently meets current needs. Already the first ESRA survey (ESRA1) rapidly grew to a global survey across 38 countries (figure 1) and is expected to grow to over 50 countries across 6 continents in the next edition (ESRA2).

    The aim of the project is to provide scientific support to road safety policy by generating comparable national data on the current road safety situation. Using a uniform sampling method, an identical questionnaire and uniform programming of the questionnaire, allows for full comparability among the countries. The first ESRA survey (ESRA1) was conducted online using representative samples (N=1,000) of the national adult populations in 38 countries (online internet access panel).

    A common questionnaire was developed and translated into 33 national langue versions. The field work was carried out in three waves: (1) June/July 2015, (2) November 2016, (3) July/August 2017. In total, ESRA1 covers almost 40,000 respondents from 38 countries across the world. The themes covered in the survey are, amongst others: ‘the use of different transport modes’, ‘involvement in road crashes’, ‘safety feeling’, ‘concerns about road safety’, ‘self-declared behaviour’, ‘attitudes towards road safety’, ‘acceptability of unsafe traffic behaviour’, ‘enforcement’, and ‘support for policy measures’. For most of these themes the ESRA1 survey investigated the following four topics: speeding, driving under influence, distraction and seat belt use. Moreover, the results can be linked to sociodemographic characteristics of the respondent such as: gender, age or educational level. ESRA1 survey targeted all type of road users, mainly car drivers but also other groups such as motorcyclists, cyclists or pedestrians (e.g. helmet use).

    The current intention is to repeat this survey on a triennial basis, retaining a core set of questions in every survey allowing the development of time series of road safety performance indicators. The next edition (ESRA2) will be launched in October 2018. More information can be found on: www.esranet.eu; Meesmann et al., 2018; Torfs et al., 2016).

    Fulltekst (pdf)
    fulltext
  • 3410. Mehta, Y
    et al.
    Birgisson, Björn
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Choubane, B
    Rubblization Over Soft Soils - The Florida Experience2002Inngår i: International Journal of Road Materials and Pavement Design, Vol. 3Artikkel i tidsskrift (Fagfellevurdert)
  • 3411.
    Meijer, Sebastiaan
    KTH, Skolan för teknik och hälsa (STH), Hälso- och systemvetenskap, Vårdlogistik. Delft University of Technology, Netherlands.
    The Power of Sponges: Comparing High-Tech and Low-Tech Gaming for Innovation2015Inngår i: Journal Simulation & Gaming, ISSN 1046-8781, E-ISSN 1552-826X, Vol. 46, nr 5, s. 512-535Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background. Innovation in transport systems has a need for simulated environments to experiment with new configurations, ideas, and solutions. Gaming is one such environment. This article applies the approach to the context of capacity allocation and traffic control innovation in the Dutch railway system. Both high-tech and low-tech games are built and applied. Aim and method. By comparing cases using low-tech and high-tech games for innovation in a related bundle of projects in the railway sector, this article aims to identify different patterns emerging from a retrospective cross case comparison. The cases aimed at testing and assessing various ideas about the innovation process through high- and low-tech gaming. Results. The high-tech cases were used to generate more quantitative data, for purposes where a concept had to be tested that has been formulated at a higher level of detail. It shows that, despite the higher precision, fidelity of high-tech simulators was not necessarily better than that of low-tech cases. None of the cases were set up to formally accept or reject hypotheses, but followed the typical innovation logic of testing and assessing ideas early in the process. Conclusions. The numerous qualitative data, gathered during the gaming sessions, illustrated the benefits and drawbacks of high- and low-tech gaming. The real world decisions made by the client, based on the gaming sessions, show that the scope of the project was broader than merely an intervention in an existing transport system. Low-tech games showed to be useful for dealing with rapid systems development (prototyping). They allow flexible role settings, varying rules, and resources. High-tech games did not provide obvious fidelity advantages, but yielded more quantitative data suitable for analysis. Recommendations. The article identifies the need for a new methodological approach: gaming supporting system/organization design.

  • 3412.
    Melander, Therese
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Optimerad anbudsprocess vid Tyréns2018Independent thesis Basic level (university diploma), 5 poäng / 7,5 hpOppgave
  • 3413.
    Melbourne, Clive
    et al.
    USalford, Manchester, UK.
    Holm, Göran
    Swedish Geotechnical Institute, Lindköping, Sweden.
    Bien, Jan
    Wroclaw University of Technology, WUT, Poland.
    Casas, Joan Ramon
    Universitat Politècnica de Catalunya, UPC, Barcelona, Spain.
    Tommor, Adrin
    USalford, Manchester, UK.
    Bengtsson, Per Evert
    Swedish Geotechnical Institute, Lindköping, Sweden.
    Kaminski, Tomasz
    WUT, Wroclaw, Poland.
    Rawa, Pawel
    WUT, Wroclaw, Poland.
    Roca, Pere
    UPC, Barcelona, spain.
    Molins, Climent
    UPC, Barcelona, Spain.
    Masonry Arch Bridges: Sustainable Bridges Background document 4.72007Rapport (Fagfellevurdert)
    Abstract [en]

    A recent survey  showed that 40% of existing rail network bridges in Europe are masonry arches. More than 60% of those bridges are over 100 years old and still carry ever increasing levels of loading and increasing volumes of traffic. Due to the constantly increasing weight of rail traffic there is increasing demand for better understanding of their life expectancy and fatigue limits. It is imperative that the bridge stock is not adversely affected by these changes in the loading regime and that appropriate assessment, modelling, repair and strengthening techniques are available.

    This background document is an attempt to address and solve the above questions.To this end, the document is divided in the following parts:

    D4.7.1 Structural assessment of masonry arch bridges

    D4.7.2 Numerical analyses of load distribution and deflections in railway bridge transitionzones due to passing trains

    D4.7.3 Methods of analysis of damaged masonry arch bridges

    D4.7.4 Potentiality of probabilistic methods in the assessment of masonry arches

    Fulltekst (pdf)
    SB 4.7
  • 3414.
    Melin, Anna
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    Lindberg, Gunnar
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    Karlsson, Robert
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Benz, T.
    Development path of Heavy Route systems: impact and socio-economic consequences. Deliverable 4.22009Rapport (Annet vitenskapelig)
  • 3415. Melin, Magnus
    et al.
    Edwards, Thomas
    Gap-analys avseende Trafikverkets förmåga att förvalta tillgångar2017Rapport (Annet vitenskapelig)
    Abstract [sv]

    Forskning- utveckling- och demonstrationsprojektet ”GAP-analys avseende TRV:s förmåga att förvalta tillgångar” inom verksamhetsområdena Väg och Järnväg har genomförts i nära samarbete med Trafikverket. Syftet med detta FUD-projektet är att hjälpa Trafikverket prioritera och beslutar om utvecklingsområden och åtgärdar för att fortsätta resan mot ökad tillgångsprestanda (mät av Trafikverkets kunder och övriga intressenter). Den GAP analysen som utförs genom en mognadsbedömning med hjälp av en strukturerade modell och medföljande förslag i denna rapport understöttar Trafikverkets vidareutveckling av sina processer och därmed sin förmåga att bedriva tillgångsförvaltningen på ett strukturerat upprepbart sätt som ”best practice”, bland annat ISO 55000 och ”International Union of Railways” (UIC:s) vägledning om den standarden, förespråka. Den strukturerade modellen har baseradats på UIC:s vägledning för järnvägsverksamheter som har försvenskats genom översättning och vidareanpassats för att också möjliggör till en viss mån även tillämpning på Trafikverkets verksamhetsområde Väg. Den har använts för att samla in intervjudata och där det bedömts erforderligt har dessa kompletterats med andra intervjudata inhämtad från ISO 55001-baserade intervjuar. En grafisk och statistisk analys av insamlade data har gjorts för att formulera och testa bedömningar av Trafikverkets mognadsgrad i sex olika nivåer för ett antal strukturella och ledningsmässiga elelement eller byggstenar relevant till tillgångsförvaltning. Slutligen har rapportförfattarna formulerat fyra huvudrekommendationer och ett antal mindre förslag för vidare arbete.

    Fulltekst (pdf)
    Gap-analys avseende Trafikverkets förmåga att förvalta tillgångar
  • 3416.
    Melkunaite, Laura
    dbi dansk brand- og sikringsteknisk institut, Denmark.
    Baker, Greg ()
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research AS, Norge.
    Cadete, Goncalo ()
    INOV.
    Carreira, Elisabete ()
    INOV.
    Gaspar, Carlos ()
    INOV.
    Gattinesi, Peter
    JRC, Italy.
    Guay, Fanny ()
    dbi dansk brand- og sikringsteknisk institut, Denmark.
    Honfi, Daniel ()
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik.
    Ioannou, Ioanna ()
    University College London, UK.
    Kinscher, J ()
    INERIS, Spain.
    Lange, David ()
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research, Brandmotstånd.
    Petersen, Laura ()
    EMSC.
    Reilly, Paul ()
    University of Sheffield, UK.
    RØD, Bjarte ()
    Arctic University of Norway, Norway.
    Salmon, Romuald ()
    INERIS, Spain.
    Stevensen, Rebecca ()
    University of Sheffield, UK.
    Theocharidou, Marianthi ()
    JRC, Italy.
    Utkin, Andrei ()
    INOV.
    IMPROVER Deliverable 1.1 International Survey2016Rapport (Annet vitenskapelig)
    Abstract [en]

    In recent years, the concept of resilience started to dominate strategic, operational as well as political domains of modern societies. Living in highly interconnected environment, where layers of infrastructures, people and economic interests interact creating both opportunities and vulnerabilities, different countries around the world turned towards resilience practices to reduce vulnerability of their critical infrastructures and societies. However, how can one implement resilience concepts without a comprehensive understanding of the concept itself? Focusing on the concept and practice of critical infrastructure resilience, this report provides a comprehensive overview of the existing scientific literature regarding the concept of resilience in general. It discusses the development of the concept of resilience and its application in societal, economic, ecological, organisational and critical infrastructure domains. The report provides an extensive discussion on the definition of resilience concepts, as well as information on scientific endeavours to implement and measure concepts of resilience.

     

    The report also contains detailed information on the definitions and implementation of the concepts of resilience in different continents, namely Europe, Africa, Asia, Oceania, North America and South America. Focusing on the concept of critical infrastructure resilience, it provides an overview of the existing official concepts of resilience, implementation tools, and general practices aimed at increasing organisational, societal, economic and technical resilience in different countries.

     

    To collect all the information, the IMPROVER consortium performed an extensive literature review on the use of resilience concepts. We also held a workshop with the associate partners, and conducted a set of personal interviews with critical infrastructure operators and resilience experts around the Europe. While conducting a number of case studies in different continents, we analysed existing region and state-level documents, and reports.

    Fulltekst (pdf)
    IMPROVER D1.1 International Survey
  • 3417.
    Mellat, Peyman
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Dynamic analysis of soil-steel composite bridges for high speed railway traffic: Case study of a bridge in Märsta, using field measurements and FE-analysis2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Soil-steel composite bridge refers to structures where a buried flexible corrugated steel pipe works in composite action with the surrounding soil. These structures are being increasingly used in road and railway projects as an alternative to standard type bridges, e.g. short- and medium span concrete beam- and portal frame bridges. On account of their economic advantage and short and easy construction operation, soil-steel composite bridges are getting more popular as railway crossings located far from the cities at the heart of the nature.

    In this research, the dynamic behaviour of soil-steel composite bridges under high-speed train passages is studied. The studied case is a short span soil-steel composite railway bridge located in Märsta close to Stockholm. The behaviour of the bridge is first observed through field measurements in terms of deflections, stresses, and accelerations at several locations on the bridge. The measured responses are then analysed in order to predict the properties of the soil and steel material working in composite action. Subsequently, 2D and 3D finite element models are developed in order to simulate the behaviour of the bridge. The models are calibrated using the field measurements through several parametric studies. The 3D-model also enables estimation of the load distribution, which is found to increase at higher train speeds. An effective width to be used in 2D analyses is proposed. Finally, the response of the bridge is studied under high-speed train models according to Eurocode.

    Fulltekst (pdf)
    fulltext
  • 3418.
    Mellat, Peyman
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Andersson, Andreas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Pettersson, Lars
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Karoumi, Raid
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Dynamic behaviour of a short span soil-steel composite bridge for high-speed railways - field measurements and FE-analysis2014Inngår i: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 69, s. 49-61Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dynamic response from passing trains at high speed is studied for a short span soil-steel composite bridge. Field measurements have been performed, comprising steel strains, vertical crown displacements and accelerations in the steel and the backfill. Soil material damping properties are estimated through analysis of the field measurements. Approaches for numerical modelling are presented, focusing on the dynamic response from passing trains. Both 2D and 3D continuum models are compared with the measured response. Based on the models, the influence of the Young’s modulus of the backfill on the bridge behaviour is investigated. The 3D-model also enables estimation of the load distribution, which is found to increase at higher train speeds. An effective width to be used in 2D analyses is proposed. A dynamic design check using the high-speed train load models in the Eurocode is presented, that for the studied bridge envisage a resonance peak at about 320 km/h.

  • 3419. Meng, Fei
    et al.
    Ma, Shuyi
    Muhammad, Yaseen
    Li, Jing
    Sahibzada, Maria
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Chi, Fengxia
    Analysis of Virgin Asphalt Brands via the Integrated Application of FTIR and Gel Permeation Chromatography2020Inngår i: Arabian journal for science and engineering, ISSN 2193-567X, Vol. 45, s. 7999-8009Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Counterfeit asphalts have often been deliberately adulterated to reduce costs, which has seriously impeded the development of road and highway construction. In this study, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and gel permeation chromatography (GPC) were applied in combination to explore a fast, accurate, low-cost and efficient method to better identify the brand and quality of asphalt. Results revealed that ATR-FTIR spectra of seven brands of asphalt were basically identical, while they differ in benzene ring substituent content and (-CH2-)n (n >= 4) content. The fingerprint intervals of virgin asphalt were 1770-1636 cm-1, 1060-985 cm-1 and 920-690 cm-1. The aging degree of the same brand of asphalt was identified by 1770-1636 cm-1 and 1060-985 cm-1, while 920-690 cm-1 range was used to identify the fingerprint interval of the original asphalt brand. GPC analysis revealed that the large molecular size (LMS) content of original Fu Lian and Shuang Long asphalt brands greatly differed which were not identified by FTIR. Owing to the thermal oxidation, the LMS content of the same brand of virgin asphalt increased by 4-6% after short-term aging. The present study based on the integrated operation of GPC-FTIR for the fast and accurate recognition and distinguishing between different brands of asphalts could be of potential practical applications.

  • 3420.
    Merk, Olaf
    International Transport Forum (ITF).
    Kumar, Uday ()
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Santos Alfageme, Maria ()
    International Transport Forum (ITF).
    Data-driven Transport Infrastructure Maintenance2021Rapport (Annet vitenskapelig)
    Abstract [en]

    What we did

    This report assesses the potential of data-driven approaches to improving transport infrastructure maintenance. It looks at trends in maintenance strategies, explores how the targeted use of data could make them more effective for different types of transport infrastructure, and looks into implications for policy. The report builds on discussions held during workshops with members of the International Transport Forum’s Corporate Partnership Board.

    What we found

    Maintenance constitutes an inevitable, albeit often invisible, part of countries’ transport policies. Increased demand for transport infrastructure accelerates infrastructure’s ageing. The effects of climate change further aggravate this. Unsurprisingly, many governments look for transport infrastructure maintenance policies that provide better value for money than current practices offer.

    Infrastructure maintenance strategies are gradually shifting towards data-driven approaches. They exploit the power of digital technologies, Big Data analytics and advanced forecasting methodologies. Data-driven approaches have gained momentum in transport infrastructure maintenance as a result of four simultaneous technological innovations.

    First, the development of digital technologies has resulted in the digitalisation of society, industry and transport, which facilitates data sharing. Second, computing technologies have provided the necessary horsepower for running the digital infrastructure. Third, the Internet of Things and sensor technology have increased the potential for automating reporting from sensors that capture and measure new phenomena and provide data sets that flow through digital infrastructures. Fourth, artificial intelligence (AI) has helped to extract information from vast amounts of data, recognising patterns beyond the capacity of individual observation and exploiting digital infrastructure and computing power.

    Policy makers are beginning to leverage these developments in various ways. Data-driven maintenance is becoming common in many parts of the transport industry.

    Railroads collect massive amounts of inspection data from different sources using various methods, such as track inspection cars and drones that gather data to model track degradation. However, the rail sector faces numerous challenges for applying Big Data analysis: a lack of specific data analysis tools, high cost of involving stakeholders and heterogeneous data sources. Also, the algorithms currently used to predict the wear of rail infrastructure only work under lab conditions.

    For road infrastructure, various automated inspection methods exist. These include vision-based methods, laser scanning, ground penetration radar and a combination of these. All are accurate and effective but usually costly. As a result, the coverage and collection frequency can prove insufficient for detectingchanging road conditions. Several pilot studies have tried to use smartphones to collect data on the state of roads to reduce deployment costs for data-driven maintenance.

    At airports, the demand for accurate real-time data has spawned systems that automatically acquire and process infrastructure data. Advanced technologies now register when deformities develop on runways. They accurately measure moisture levels, temperature, strain and other factors relevant to wear and degradation. Several airports have built, or plan to build, concrete pavements with embedded strain gauges and other sensors to monitor the stress in the material caused by aircraft.

    Overall, data-driven approaches to infrastructure maintenance promise to enhance fact-based decision making and capabilities to predict the remaining useful life of assets. They can also improve cost efficiency and environmental sustainability. However, some new challenges need to be addressed, notably for the use of AI. AI predicts future behaviour based on historical data. Yet all predictions can prove incorrect where events do not follow past trends.

    What we recommendScale up and speed up the deployment of data-driven approaches to transport infrastructure maintenance

    Transport infrastructure maintenance could benefit from a broader and accelerated roll-out of data-driven approaches. These could improve the quality of assets, enhance the life cycles and save costs - especially when the relevant technologies are well-known, such as sensor technologies. In some cases, more tests and pilot projects will be useful, notably where leveraging data technologies for more effective maintenance policies poses specific challenges, as is the case of artificial intelligence in the railway sector.

    Update regulation and guidelines for transport infrastructure maintenance to facilitate the introduction of more data-driven approaches

    Current regulations and guidelines apply to condition-based maintenance strategies. These may set requirements that are ill-adapted to data-driven approaches to maintenance and may hamper their roll-out. Policy makers should ensure that the policies applied to data-driven approaches do not stifle their potential benefits.

    Ensure data-driven infrastructure maintenance approaches follow good practices in data governance

    The use of data in infrastructure maintenance must be in line with privacy protection laws and regulations. All data should be anonymised and encrypted. Location and trajectory data should be covered by the most robust protection methods, as they create the severest vulnerabilities for citizens. Tools to limit privacy risks include non-disclosure agreements between data users and providers, the involvement of trusted third parties to conduct the data collection and the development of “safe answers” approaches, in which only query results are exchanged instead of raw data. Governments could also broker data-sharing partnerships for the purpose of data-driven maintenance, for instance, between data providers and infrastructure managers. However, it may want to limit such partnerships to data of public interest and require purpose specificity and data minimisation.

    Fulltekst (pdf)
    fulltext
  • 3421.
    Meyer, Fredrik
    et al.
    Trafikverket.
    Faith-Ell, Charlotta
    WSP.
    Ericson, Johan
    WSP.
    Meyer, Fredrik ()
    Trafikverket.
    New Main Lines – Purpose and Overarching Goals: Executive Summary2020Rapport (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    This Memorandum is a translated version of Nya stambanor – syfte och övergripande mål: Kortversion av slutrapport (New main lines – purpose and overarching goals: Executive summary (2020:052)). The full report (2019:211) describes the entire process of developing the  intended purpose and overarching goals, while this Memorandum only reproduces the outcome: the agreed Goal Structure, Purpose and Overarching Goals for the new main lines. The full report is available in Swedish.”

    Fulltekst (pdf)
    New main lines
    Download (jpg)
    New main lines
  • 3422.
    Meyer, Fredrik
    et al.
    Trafikverket.
    Faith-Ell, Charlotta
    WSP.
    Ericson, Johan
    WSP.
    Nya stambanor – syfte och övergripande mål: Kortversion av slutrapport2020Rapport (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    Denna PM är en kortversion av rapporten Nya stambanor – syfte och övergripande mål som togs fram inom projektet Målarbete 2.0. I huvudrapporten beskrivs hela arbetsprocessen fram till beslutat syfte och övergripande mål. Denna PM återger endast resultatet dvs. beslutad målstruktur, syfte och övergripande mål och dess preciseringar för nya stambanor.

    Fulltekst (pdf)
    fulltext
    Download (jpg)
    presentationsbild
  • 3423.
    Meyer, Jonas
    et al.
    EMPA, Dübendorf, Switzerland.
    Bischoff, Reinhard
    EMPA, Dübendorf, Switzerland.
    Feltrin, Glauco
    EMPA, Dúbendorf, Switzerland.
    Krüger, Markus
    Institute of Construction Materials, University of Stuttgart, Germany.
    Grosse, Christian U
    Institute of Construction Materials, University of Stuttgart, Germany.
    Chatzichrisafis, Panagiotis
    Institute of Construction Materials, University of Stuttgart, Germany.
    Data analysis and reduction methodologies for wireless sensor networks: Sustainable Bridges Background document 5.82007Rapport (Fagfellevurdert)
    Abstract [en]

    This report describes procedures and algorithms for data analysis and reduction methodologies regarding vibration analysis and acoustic emission techniques (AET) utilized for a prototype bridge monitoring system which is based on wireless sensor network (WSN) technology. The network consists of a terminal or base station (data logging and configuration unit), representing the data sink in the network, and several tens of sensor nodes spread over a bridge and representing the data sources. Each sensor node is equipped with sensors, a microcontroller and a radio transceiver. All nodes together form a multi-hop communication network.

    The laboratory and field tests described demonstrate that this concept is feasible even on low power WSN platforms and that it is a key element for the successful application of wireless sensor networks in long term structural monitoring.

    Fulltekst (pdf)
    SB 5.8
  • 3424.
    Meyer, Jonas
    et al.
    EMPA, Dübendorf, Switzerland.
    Bischoff, Reinhard
    EMPA, Dübendorf, Switzerland.
    Feltrin, Glauco
    EMPA, Dúbendorf, Switzerland.
    Krüger, Markus
    Institute of Construction Materials, University of Stuttgart, Germany.
    Saukh, Olga
    Institute of Construction Materials, University of Stuttgart, Germany.
    Bachmeier, Sebastian
    Institute of Construction Materials, University of Stuttgart, Germany.
    Prototype Implementation of a Wireless Sensor Network: Sustainable Bridges Background document 5.72007Rapport (Fagfellevurdert)
    Abstract [en]

    This report describes the prototype of a bridge monitoring system based on wireless sensor network technology. The network consists of a terminal or base station (data logging and configuration unit), representing the data sink in the network, and several tens of sensor nodes spread over a bridge and representing the data sources. Each sensor node is equipped with sensors, a microcontroller and a radio transceiver. All nodes together form a multi-hop communication network. That is, each sensor node figures as data source and relaying station, forwarding data received from adjacent nodes. The nodes cooperatively organize itself into a network. That is, the paths of data packets to the base station are set up dynamically. Therefore, if a single node or parts of the network fail, new paths to the base station are established. Furthermore, any number of nodes can be added at any time without implementing specific routing instructions. The routing mechanism of the data packets is optimised for maximizing the network’s lifetime, i.e. energy consumption is distributed evenly among the nodes.

    Fulltekst (pdf)
    SB 5.7
  • 3425. m.fl., Bengt Sandblad
    D8.4 Simulations of the Iron Ore line2014Rapport (Annet vitenskapelig)
    Abstract [en]

    The purpose of this document is to describe simulations performed for the Iron Ore Line (IOL), in order to test and evaluate the systems for operational re-planning in case of per-turbations. The simulator Hermes has been used for the simulations, with input data describing the IOL. When the simulator has been found valid for the IOL, a number of per-turbations scenarios have been used for evaluation of the ON-TIME modules for perturba-tion handling. The Perturbation Management Modules (PMM) have been connected to the simulator system. The PMM detects perturbations and the need for re-planning and calcu-lates a new real time traffic plan (RTTP), which is automatically executed to the (simulat-ed) traffic control system. Two different scenarios have been used for evaluation studies. One with a delayed loaded iron ore train and one with speed restrictions between two stations. The evaluation studies have resulted in the following conclusions: • The Hermes simulator can simulate the traffic on the IOL, for undisturbed traffic as well as for traffic with certain perturbations. However, with a number of limita-tion, as discussed above. • The developed systems for automatic re-planning, the PMM modules, are able to handle the perturbations specified in some scenario for the IOL. • That evaluations show that a number of requirements must be fulfilled, it the sys-tems are going to be used in real traffic control on the IOL. • That the results give us a good basis for future research and development. • It will be necessary to perform more advanced evaluations, in order to specify these requirements in detail. Final remarks are that the results so far are very interesting for future development in Sweden. Important will be to integrate the PMM modules with a fully interactive envi-ronment. The present system in Boden, with STEG and CATO, can profit from efficient systems for optimal re-planning and decision support. The human controllers’ tasks must be coordinated with the more automated functions and their user interfaces must visualize important aspects of the PMM actions.

    Fulltekst (pdf)
    D8.4 Simulations of the Iron Ore line
  • 3426.
    Miao, Xuehui
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Duan, Qiong
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Parametric vibration of stay cable and vibration control2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    A stay cable might undergo large amplitude vibration excited by deck and pylon when the frequency of deck or pylon is twice as the natural frequency of the cable, so called parametric vibration.

    Several analytical models are studied to observe the behavior of a cable when parametric vibration occurs and verified by the results obtained from ABAQUS. They are also used to investigate significance of cable-deck interaction phenomenon. Parametric study has been conducted to investigate the effect of excitation, static tension, damping of cable, viscous damper and tuned mass damper (TMD) on cable vibration.

    As concluded, cable-deck interaction is significant to induce cable vibration. Viscous damper can mitigate vibration when the excitation is small. As for large excitation, TMD has an advantage.

  • 3427.
    Mihocic, E.
    et al.
    SHAPE Australia, Sydney, Australia.
    Gharehbaghi, K.
    RMIT University, Melbourne, Australia.
    Hilletofth, Per
    Jönköping University, Tekniska Högskolan, JTH, Industriell produktutveckling, produktion och design.
    Tee, K. F.
    INTI International University, Nilai, Malaysia.
    Myers, M.
    Heriot-Watt University, Dubai Campus, Dubai, United Arab Emirates.
    Augmenting the cities’ and metropolitan regional demands for mega rail infrastructure: the application of SWOT and factor analysis2024Inngår i: Smart and Sustainable Built Environment, ISSN 2046-6099, E-ISSN 2046-6102Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Purpose: In successfully meeting city and metropolitan growth, sustainable development is compulsory. Sustainability is a must-focus for any project, particularly for large and mega rail infrastructure. This paper aims to investigate to what degree social, environmental and economic factors influence the government when planning sustainable rail infrastructure projects. To respond to such a matter, this paper focuses on two Australian mega-rail projects: the South West Rail Link (SWRL) and the Mernda Rail Extension (MRE). Design/methodology/approach: As the basis of an experimental evaluation framework strengths, weaknesses, opportunities and threats (SWOT) and factor analysis were used. These two methods were specifically selected as comparative tools for SWRL and SWRL projects, to measure their overall sustainability effect. Findings: Using factor analysis, in the MRE, the factors of network capacity, accessibility, employment and urban planning were seen frequently throughout the case study. However, politics and economic growth had lower frequencies throughout this case study. This difference between the high-weighted factors is likely a key element that determined the SWRL to be more sustainable than the MRE. The SWOT analysis showed the strengths the MRE had over the SWRL such as resource use and waste management, and natural habitat preservation. These two analyses have shown that overall, calculating the sustainability levels of a project can be subjective, based on the conditions surrounding various analysis techniques. Originality/value: This paper first introduces SWRL and MRE projects followed by a discussion about their overall sustainable development. Both projects go beyond the traditional megaprojects' goal of improving economic growth by developing and enhancing infrastructure. Globally, for such projects, sustainability measures are now considered alongside the goal of economic growth. Second, SWOT and factor analysis are undertaken to further evaluate the complexity of such projects. This includes their overall sustainable development vision alignment with environmental, economic and social factors.

  • 3428.
    Mikhaltchouk, Inga
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande. KTH Royal Institute of Technology, Sweden.
    Forsman, Mikael
    KTH Royal Institute of Technology, Sweden.
    Concrete Casting – Construction Engineers’ Attitudes and Knowledge About Work Environment, Risk Factors, Injuries and Self-compacting Concrete2021Inngår i: IEA 2021: Proceedings of the 21st Congress of the International Ergonomics AssociationPart of the Lecture Notes in Networks and Systems book series (LNNS, volume 221), Springer Science and Business Media Deutschland GmbH , 2021, s. 323-328Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The construction industry has one of the highest frequencies of sick leaves caused both by accidents and by work-related diseases. Casting is one example of a demanding task. After casting with regular concrete, the concrete mass needs to be manually vibrated to reduce the air and to fill the formwork properly. During this activity workers are exposed to forward bent postures, repeated heavy lifts, noise and hand-arm vibrations. Self-compacting concrete (SCC) is a fluid concrete and as such, does not need vibrations. In addition, one may expect economic benefits when using SCC. Despite the advantages of SCC its market share in Sweden is about 10%, and lower than in a neighboring country. There is yet no explanation for the low usage of SCC in Sweden. The aim of this study is to reach a deeper understanding of construction engineers’ attitudes and knowledge concerning work health and work environments during concrete casting, and about SCC and its usage. One-hour-interviews were conducted with 6 male construction engineers. The results indicated that respondents were familiar with risks for accidents, but much less familiar with risks for musculoskeletal disorders, and with risks from hand-arm vibrations. The study also revealed low level of knowledge about SCC and other new methods and materials that could improve and streamline processes at a construction site. © 2021, The Author(s)

  • 3429.
    Mikhaltchouk, Inga
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Forsman, Mikael
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Ergonomi.
    Concrete Casting – Construction Engineers’ Attitudes and Knowledge About Work Environment, Risk Factors, Injuries and Self-compacting Concrete2021Inngår i: Proceedings of the 21st Congress of the International Ergonomics Association (IEA 2021) Congress of the International Ergonomics Association, Springer, 2021, Vol. 221, s. 323-328Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The construction industry has one of the highest frequencies of sick leaves caused both by accidents and by work-related diseases. Casting is one example of a demanding task. After casting with regular concrete, the concrete mass needs to be manually vibrated to reduce the air and to fill the formwork properly. During this activity workers are exposed to forward bent postures, repeated heavy lifts, noise and hand-arm vibrations. Self-compacting concrete (SCC) is a fluid concrete and as such, does not need vibrations. In addition, one may expect economic benefits when using SCC. Despite the advantages of SCC its market share in Sweden is about 10%, and lower than in a neighboring country. There is yet no explanation for the low usage of SCC in Sweden. The aim of this study is to reach a deeper understanding of construction engineers’ attitudes and knowledge concerning work health and work environments during concrete casting, and about SCC and its usage. One-hour-interviews were conducted with 6 male construction engineers. The results indicated that respondents were familiar with risks for accidents, but much less familiar with risks for musculoskeletal disorders, and with risks from hand-arm vibrations. The study also revealed low level of knowledge about SCC and other new methods and materials that could improve and streamline processes at a construction site.

  • 3430.
    Milder, Ann-Cathrin
    WSP.
    Väg 25, Halmstad: Fördjupad riskanalys och förslag till åtgärder2019Rapport (Annet vitenskapelig)
    Abstract [sv]

    Riskanalysen beskriver grundvattenförekomsten längs väg 25, öster om Halmstad, och bedömer de risker som vägtrafiken innebär för förorening av grundvattnet. Analysen utmynnar i att det föreligger en låg risk för förorening. Rapporten föreslår därför, i linje med gällande handbok, inga förebyggande åtgärder.

    Fulltekst (pdf)
    fulltext
    Download (jpg)
    presentationsbild
  • 3431.
    Milder, Ann-Cathrin
    WSP.
    Väg 26 NO Halmstad: Fördjupad riskanalys och förslag till åtgärder2019Rapport (Annet vitenskapelig)
    Abstract [sv]

    Riskanalysen beskriver grundvattenförekomsten längs väg 26, nordost om Halmstad, och bedömer de risker som vägtrafiken innebär för förorening av grundvattnet. Analysen utmynnar i att det föreligger en hög risk för förorening. Rapporten föreslår en kombination av räcken, kantsten, dagvattenledning och fördröjningsdamm.

    Fulltekst (pdf)
    fulltext
    Download (jpg)
    presentationsbild
  • 3432.
    Milder, Ann-Chatrin
    WSP.
    Väg E6/E20, Halmstad: Fördjupad riskanalys och förslag till åtgärder2019Rapport (Annet vitenskapelig)
    Abstract [sv]

    Riskanalysen beskriver grundvattenförekomsten längs väg E6 genom Halmstad tätort och bedömer de risker som vägtrafiken innebär för förorening av grundvattnet. Analysen utmynnar i att det föreligger en hög risk för förorening. Rapporten föreslår en kombination av räcke, kantsten, täta diken, dagvattensystem och fördröjningsdammar.

    Fulltekst (pdf)
    fulltext
    Download (jpg)
    presentationsbild
  • 3433.
    Miliutenko, Sofiia
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms).
    Potting, Josepha
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Miljöstrategisk analys (fms).
    Life cycle energy and climate change considerations in the road infrastructure planning processes in the Netherlands and Sweden2012Konferansepaper (Annet vitenskapelig)
  • 3434.
    Min, Xinzhe
    et al.
    School of Civil Engineering and Architecture, Nanjing Institute of Technology, Nanjing, China.
    Zhang, Jiwen
    Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, National Engineering Research Center for Prestressing Technology, School of Civil Engineering, Southeast University, 211189 Nanjing, China.
    Li, Xing
    Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, National Engineering Research Center for Prestressing Technology, School of Civil Engineering, Southeast University, 211189 Nanjing, China.
    Wang, Chao
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Tu, Yongming
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, National Engineering Research Center for Prestressing Technology, School of Civil Engineering, Southeast University, 211189 Nanjing, China.
    Sas, Gabriel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. SINTEF Narvik AS, Narvik 8517, Norway.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    An experimental study on fatigue debonding growth of RC beams strengthened with prestressed CFRP plates2022Inngår i: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 273, artikkel-id 115081Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Externally bonded Fiber Reinforced Polymer (FRP) laminates are increasingly used to strengthen Reinforced Concrete (RC) members. However, FRP debonding remains a major drawback of this strengthening method. To better understand the mechanisms of FRP debonding, six RC beams strengthened with prestressed or non-prestressed Carbon Fiber Reinforced Polymer (CFRP) plates were subjected to static and fatigue loading. CFRP plate debonding was observed in both cases. However, the mechanism of debonding differed: under cyclical fatigue loading, debonding was initiated under both loading points simultaneously and propagated synchronously towards the nearest support whereas in static tests debonding began under a single loading point and progressed suddenly towards its adjacent support. The results also showed that stress redistribution induced coupling between accumulated fatigue damage in the steel reinforcement and fatigue debonding of the CFRP plate, accelerating the fatigue failure of the specimens.

  • 3435.
    Min, Xinzhe
    et al.
    School of Civil Engineering and Architecture, Nanjing Institute of Technology, Nanjing, China.
    Zhang, Jiwen
    Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, National Engineering Research Center for Prestressing Technology, School of Civil Engineering, Southeast University, 211189, Nanjing, China.
    Tu, Yongming
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, National Engineering Research Center for Prestressing Technology, School of Civil Engineering, Southeast University, 211189, Nanjing, China.
    Li, Xing
    Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, National Engineering Research Center for Prestressing Technology, School of Civil Engineering, Southeast University, 211189, Nanjing, China.
    Wang, Chao
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Sas, Gabriel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    A full-range fatigue life prediction model for RC beams strengthened with prestressed CFRP plates accounting for the impact of FRP debonding2024Inngår i: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 301, artikkel-id 117305Artikkel i tidsskrift (Fagfellevurdert)
  • 3436.
    Mineur, Christian
    Trafikverket.
    Bristanalys Hjulstabron: passage för större fartyg till Mälarhamnarna2021Rapport (Annet vitenskapelig)
    Abstract [sv]

    Nuvarande Hjulstabron är en öppningsbar bro och kommer att utgöra en begränsning i utveckling av handelssjöfart i Mälaren när övriga farledsåtgärder är genomförda. Genom en ombyggnad av Södertälje sluss och kanal, en utveckling av Mälarhamnar och den farledsfördjupning som nu pågår, kommer transporter för gods till och från hamnarna i Mälaren först att kunna nå tänkt fartygsstorlek och ökat tonnage efter ett utbyte av aktuell bro för Riksväg 55 i Hjulsta. Större fartyg i enlighet med de nya max måtten för fartyg i Mälaren kan användas samtidigt som sjöfartens användbarhet och säkerhet ökar. Den nuvarande öppningsbara bron bedöms även ha stora behov av att rekonstrueras närmaste 10 åren p g a åldersskäl.

    Mer godstransporter till sjöss kan minska belastningen på det ansträngda väg- och järnvägssystemet runt Mälaren och i Stockholmsområdet. Detta samtidigt till nytta ur ett klimatperspektiv. Hela Mälarprojektet inklusive kvarstående begränsande del som Hjulstabron utgör anpassas för att bidra till mer hållbara transporter och hantera behovet av att utveckla våra vattenvägar i Mälaren kopplat till När- och kustsjöfarten i Östersjön.

    Fulltekst (pdf)
    Bristanalys Hjulstabron
    Download (jpg)
    presentationsbild
  • 3437.
    Mirzadeh, Iman
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Butt, Ali Azhar
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Toller, Susanna
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Miljöstrategisk analys.
    Birgisson, Björn
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    A Life Cycle Cost Approach based on the Calibrated Mechanistic Asphalt Pavement Design Model2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Life Cycle Cost Analysis (LCCA) provides cost estimation over the life time of a project and thereby helps road administrations, designers, and contractors with choosing an economical design. Calculation of the costs can be based on a pavement design model, such as the Calibrated Mechanistic model (CM), in order to capture the mechanical behaviour of the asphalt pavement. This study aimed to develop an approach for performing comparative LCCA in order to find the most economical design alternative in terms of the total cost for the pavement design life. The integrated LCCA-CM approach was used to evaluate different design alternatives with different rehabilitation intervals for asphalt pavements. 

  • 3438.
    Mirzadeh, Iman
    et al.
    Statens väg- och transportforskningsinstitut, Infrastruktur, INFRA, Drift och underhåll, DOU.
    Eriksson, Olle
    Statens väg- och transportforskningsinstitut, Infrastruktur, INFRA, Drift och underhåll, DOU.
    Lundström, Robert
    NCC.
    Performance requirements in design-build contracts: development of a risk assessment model2020Rapport (Annet vitenskapelig)
    Abstract [en]

    The gradual shift in procurement of road infrastructures from traditional design-bid-build (DBB) to design-build (DB) contracts, have resulted in an ever-increasing need for contractors and consultants to assess and predict the technical performance of selected designs and corresponding risks. Moreover, there is a great interest for the road administration to better motivate the type of contract and the procurement strategy based on risks and outcomes in road projects. This report has focused on developing a model for evaluation of the impact of performance requirements in DB and design-bidmaintain (DBM) projects. The model can analyse the risk of exceeding the maximum requirements during the warranty period. Therefore, it can be applied by contractors for evaluation of the technical risk not only at the bidding stage but also during the warranty period. It can also be used by the road administration as a decision support tool for setting performance requirements at the project level.

    Fulltekst (pdf)
    fulltext
  • 3439.
    Mirzadeh, Iman
    et al.
    Statens väg- och transportforskningsinstitut, Drift och underhåll, DOU.
    Eriksson, Olle
    Statens väg- och transportforskningsinstitut, Drift och underhåll, DOU.
    Lundström, Robert
    NCC.
    Performance requirements in design-build contracts: development of a risk assessment model2020Rapport (Annet vitenskapelig)
    Abstract [en]

    The gradual shift in procurement of road infrastructures from traditional design-bid-build (DBB) to design-build (DB) contracts, have resulted in an ever-increasing need for contractors and consultants to assess and predict the technical performance of selected designs and corresponding risks. Moreover, there is a great interest for the road administration to better motivate the type of contract and the procurement strategy based on risks and outcomes in road projects. This report has focused on developing a model for evaluation of the impact of performance requirements in DB and design-bidmaintain (DBM) projects. The model can analyse the risk of exceeding the maximum requirements during the warranty period. Therefore, it can be applied by contractors for evaluation of the technical risk not only at the bidding stage but also during the warranty period. It can also be used by the road administration as a decision support tool for setting performance requirements at the project level.

    Fulltekst (pdf)
    FULLTEXT01
  • 3440.
    Mirzahassanagha, Zeinab
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Malo, Eva
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    Performance of reinforced concrete bridges strengthened with Carbon Fiber Reinforced Polymers: Case study: Essinge Bridge over Pampaslänken2021Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This master thesis deals with the performance of existing reinforced concrete bridges strengthened with externally bonded carbon fibre reinforced polymers (CFRP). One of the main aims of this work is to understand the functionality of such an external strengthening method applied to a concave surface in a heavy concrete structure such as a bridge. Another important goal is to investigate the bond behavior of this method. To accomplish the aforementioned aims a case study bridge is chosen to be examined. The Essinge bridge located in the central Stockholm, is the selected bridge in which this report will focus on.

    Externally strengthening an existing bridge is a method used to both preserve as well as improve the existing structure. Some examples justifying the need to use such a technique are: the degradation of materials or changes in the bearing capacity of the structure which might be the result of increased traffic loads. In the case of Essinge bridge, the structure is strengthened with externally bonded CFRP sheets after the extension of the bridge which led to changes in the statical mode of action of the structure. An additional reason which makes this case interesting to study is the ’’concave’’ surface on which the CFRP sheets are applied to.

    To study the Essinge bridge in detail, both a numerical analysis and a three-dimensional finite element model is used. All the numerical simulations are performed in the Abaqus software. It is important to mention that for the majority of the simulations a two-axle vehicle load of 300kN (per axle) is applied to the structure. Moreover, a quality assurance of the FE model is carried out to verify the functionality of the model. Some of the results coming from these analyses can be compared with measurements from the monitoring system placed on the bridge. Moreover, other simulation results could be compared with results coming from a test loading performed on the bridge on May 2021. From this comparison, a satisfactory agreement could be found in the peak values of normal strain in concrete and CFRP.

    Due to time limitations, only linear static analyses are performed. Consequently, in order to capture the non-linearity of the concrete, the Extended Finite Element Method (XFEM) available in Abaqus is used to model a possible crack in the concrete. More specifically, the crack is placed in the concrete part of the deck plate where the maximum value of normal stress is obtained.

    The bond behavior between the concrete and the CFRP sheets is modelled in two different ways. The first way represents a ’’perfect’’ bond between these two materials meanwhile the second one is based on the so-called Cohesive Zone Method (CZM). The fundamental difference between these two methods is that when using the CZM, a possible failure mode in the bond layer can be captured. Moreover, the input data and parameters defined in the CZM have a detrimental role in the obtained results.

    It can be noted that the results of the case study bridge cannot be generalized. On the other hand, a better understanding about the external strengthening method implemented on the example of Essinge bridge is obtained. By using the CZM, a vehicle load which could initiate damage in the bond layer could be found.

    Fulltekst (pdf)
    fulltext
  • 3441.
    Mirzanamadi, Raheb
    et al.
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Miljö, MILJÖ.
    Nyberg, Erik
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Miljö, MILJÖ.
    Torstensson, Peter
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Miljö, MILJÖ. Department of Mechanics and Maritime Sciences / CHARMEC, Chalmers University of Technology, Sweden.
    Andersson-Sköld, Yvonne
    Statens väg- och transportforskningsinstitut, Samhälle, miljö och transporter, SAMT, Miljö, MILJÖ. Department of Architecture and Civil Engineering, Chalmers University of Technology, Sweden.
    Lateral Track Buckling in Sweden: Insights from Operators and Infrastructure Managers2024Inngår i: CivilEng, E-ISSN 2673-4109, Vol. 5, nr 1, s. 136-149Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rail transport is expected to become a key component in the development of a long-term sustainable transport system. The planning, construction, operation, and maintenance of railway infrastructure are crucial in this effort. Hence, it is essential to ascertain that the railway infrastructure withstands and is adapted to extreme weather conditions and climate change. This study focuses on evaluating climate adaptation measures for lateral track buckling in Sweden. Through a literature review and interview with an expert at Swedish Transport Administration, it is highlighted that the maintenance status of railway infrastructure plays a significant role in the occurrence of lateral track buckling. According to the expert, inadequate track maintenance is the primary cause of lateral track buckling rather than weather variables like air temperature. The interview also clarifies that the chain of events related to the handling of track buckling is mainly initiated by the observation of a discrete lateral irregularity by a train driver, whereupon the train dispatcher at the traffic management center stops traffic until the location in the track has been inspected by a track entrepreneur. During the inspection, up to half of the observed cases of track buckling turn out to be false.

    Fulltekst (pdf)
    fulltext
  • 3442.
    Mirzazade, Ali
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    An Algorithmic Framework for Intelligent Concrete Structural Defects Detection and Classification2023Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The primary objective of inspecting concrete civil structures is to gather information concerning the deterioration of concrete elements, including issues like concrete cover cracking, delamination, or corrosion. Typically, this data is documented through field inspection notes, hand-drawn sketches, and photographs. Unfortunately, this information is often stored in diverse formats, relying on close-range images and paper-based records. Moreover, the process heavily depends on the inspector's experience, structural knowledge, and familiarity with the material properties of the system under investigation. Traditional inspection methods have inherent limitations, as they generally focus on easily accessible areas due to time constraints, safety concerns, or the challenging terrains often encountered in the field. This is particularly relevant when inspecting large structures like bridges, where examining the entire area would be time-consuming and potentially unsafe. The transfer of knowledge from one inspection period to the next becomes problematic when different inspectors are involved. Hence, there is a compelling need to explore modern inspection and monitoring techniques for structures, with a focus on reducing disruption and enhancing the efficiency and reliability of data acquisition.

    In this context, the previously published licentiate thesis was aimed to contribute by developing optical alternatives that complement existing techniques. These alternatives should be cost-effective, suitable for on-site application, and easily deployable. To align with the objectives of this research project, the following research questions were addressed before in the licentiate seminar:

    1.    How accurate is Close-Range Photogrammetry (CRP) for monitoring geometric deviations and detecting defects?

    2.    In pursuit of maximum accuracy and minimal computation time in crack detection, which convolutional neural network (CNN) architecture performs best in classification and semantic segmentation tasks?

    3.    Is there a correlation between surface deformations in reinforced concrete, measured through Digital Image Correlation (DIC), and strains in the embedded reinforcement?

    However, there are still challenges to be addressed. Concrete civil structure inspection involves more than just defect detection and measurement. In this final thesis, the objective is to discuss an algorithm for creating an intelligent machine capable of classifying concrete defects. This requires the computer, acting as the inspector, to possess substantial knowledge about the concrete structure, including protocols, standards, guidelines, and an understanding of the overall structure's status. Consequently, two additional research questions are introduced:

    1.    Building on our previous discussion in the licentiate seminar regarding the correlation between surface deformations and strains in embedded rebars, we aim to enhance the accuracy of the strain estimation. To achieve this, we intend to train intelligent regression models using available experimental data and newly generated synthetic data. Research Question 1: How can we estimate strains on embedded rebars with the application of machine learning regression, employing a hybrid-learning approach? This question is explored in the paper "Prediction of strain in embedded rebars for RC member: application of a hybrid learning approach."

    2.    While computer vision techniques are effective in defect detection, structural health assessment encompasses more than just identifying defects. The objective is to provide a comprehensive solution that bridges the gap between defect detection, classification, and assessment, ultimately contributing to a more accurate understanding of detected defects. Research Question 2: How can we bridge the gap between defect detection and classification to achieve effective defect classification? This question is the subject of the forthcoming manuscript, "Defect Classification and Structural Assessment of Concrete Bridges: A Data-Driven Decision-Making Approach".

    Fulltekst (pdf)
    fulltext
  • 3443.
    Mirzazade, Ali
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Autonomous bridge inspection based on a generated digital model2022Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Railway owners manage geographically dispersed networks comprising major elements of ageing infrastructure that are very susceptible to natural hazards. Consequently, transport agencies must address maintenance issues to guarantee serviceability and safety. This includes increased inspections and investing into structural health monitoring (SHM) programs. Regular SHM of existing bridges are usually scheduled during their service life to evaluate their health and as part of proactive maintenance where future deterioration is anticipated. Typically, a routine inspection consists of field measurements and visual observations made by a bridge inspector. However, disruption to civil infrastructure services due to scheduled maintenance work, visual inspection, etc. is increasing. 

    The main purpose of SHM is to collect information such as geometry, previous and ongoing concrete deterioration, steel rebar corrosion, water seepage, concrete cover delamination, deflections, or settlements etc. The way such data are documented is through field inspection notes, freehand sketches, and photographs. Oftentimes, the data is stored in different systems and data collection and visualization still relies on paper-based record keeping processes. In addition, the procedure is highly dependent on the inspector’s experience [1], and knowledge of the structural behavior, together with the material properties of the system being investigated. The method has its limitations in the sense that only accessible parts are investigated due to time shortage, safety issues, or the difficult terrain in which the structure is sometimes located. This is especially true for large structures, such as bridges, where investigating the whole area would be highly time-consuming and potentially unsafe [2]. Honfi et al. [3] noted that the inspection’s duration is highly dependent on the bridge span (less than 10m can amount to 0.5 days and bigger than 100 m can amount to 20 days). In addition, defects can only be detected when their presence is visible to the naked eye, so they may already affect the life of the structure. Graybeal et al. [4] noted that routine inspections have relatively poor accuracy, with the following factors affecting the reliability of these results: inspector fear of traffic, near visual acuity, color vision, accessibility, and complexity. Furthermore, knowledge transfer from one inspection period to another becomes difficult when different inspectors carry out the investigation. Therefore, there is a strong need to identify new inspection and monitoring techniques for infrastructure that, in addition to being contactless and productive, reduce disruption, and improve the efficiency and reliability of the acquired data.

    With the expansion of the low-cost consumer cameras, photogrammetry could play an important role in supporting SHM on existing bridges. Vaghefi et al. [5] carried out a study of 12 remote sensing technologies and their potential to detect a series of common problems on US bridges. They concluded that 3D optical technologies have potential for documenting surface-related defects. Faster bridge inspection and visualization was described when aiming to quantify the defects over bridge deck surfaces with a low cost and easily deployable technology. Other studies reported on the use of photogrammetry as alternative to traditional measurement applied in laboratory environment; a review is done by Baqersad et al. [6]. The researchers themselves have a well-proven experience in applying photogrammetry for determination of failure mechanisms in concrete structures, defect detection, and monitoring full-field deformations. In an effort, by Popescu et al. [7], to develop new monitoring and inspection methods with a preliminary study, photogrammetry and terrestrial laser scanning utilized to generate the 3D model of six railway bridges located in northern Sweden. Results have shown an acceptable performance of 3D model of existed infrastructure generated by photogrammetry. Therefore, the current project will contribute with optical alternatives to traditional SHM approaches that are low-cost, suitable for field application, and easily deployable.

    The results indicate that bridge inspection on generated digital model is more reliable, productive, and accessible than traditional surveys. For 3D model generation we used photogrammetry technique, which is more efficient and cost-effective compared to the laser scanning, but improvements in accuracy and automation during the image acquisition phase are still required. 

    The approach of autonomous defect detection performed on two case studies. Two types of defects including cracks, and block opening in a hard-to-access area was successfully detected and measured by pixel-wise mapping to an orthophoto. The proposed method has considerable potential in automated infrastructure inspection but some problems due to background noise remain to be overcome. The existence of noisy patterns such as shadows, dirt, and snow or water spots on surfaces makes damage detection very challenging, especially for the fine cracks. Overall, while the automated inspection technique proposed herein performs well, it clearly still requires supervision by a human inspector.

    Fulltekst (pdf)
    fulltext
  • 3444.
    Mirzazade, Ali
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Nodeh, Maryam Pahlavan
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, EISLAB.
    Popescu, Cosmin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. SINTEF Narvik AS, Narvik, Norway.
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Utilization of Computer Vision Technique for Automated Crack Detection Based on UAV-Taken Images2021Inngår i: International Conference of the European Association on Quality Control of Bridges and Structures: EUROSTRUCT 2021: Proceedings of the 1st Conference of the European Association on Quality Control of Bridges and Structures / [ed] Carlo Pellegrino; Flora Faleschini; Mariano Angelo Zanini; José C. Matos; Joan R. Casas; Alfred Strauss, Springer, 2021, s. 713-720Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Conventional bridge inspection is usually performed by experienced engineers, trying to detect and document damage patterns manually. By increased number of built Bridges, there is a growing interest in automated damage detection methods. Therefore, the field of autonomous bridge inspection with the application of machine learning techniques on UAV-taken images is gaining popularity. Due to recent technological advancement, a large number of datasets can be collected, with a high rate of productivity and accuracy, to train convolutional neural networks (CNNs) leading us to automated Structural health monitoring (SHM). In this paper, a case study is chosen to scan two times with almost one year as a time interval. In the first scanning, dataset was gathered to train four different CNNs. Then, the performance of CNNs was compared for the purpose of autonomous crack detection in the second round of scanning. Models evaluated on a number of performance metrics, namely- (i) accuracy, (ii) loss, (iii) computation time, (iv) model size, and (v) architectural depth. Finally, the performance of studied CNNs is discussed, which can lead researchers in the Transfer-Learning approach to generate a model for damage detection with a limited number of datasets prepared in the first turn of bridge inspection. 

  • 3445.
    Mirzazade, Ali
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. SINTEF Narvik AS, Narvik, 8517, Norway.
    Popescu, Cosmin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. SINTEF Narvik AS, Narvik, 8517, Norway.
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Application of close range photogrammetry in structural health monitoring by processing generated point cloud datasets2021Inngår i: IABSE Congress Ghent 2021: Structural Engineering for Future Societal Needs / [ed] H. H. (Bert) Snijder; Bart De Pauw; Sander van Alphen; Pierre Mengeot, International Association for Bridge and Structural Engineering (IABSE) , 2021, s. 450-458Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In bridge inspection, vertical displacement is a relevant parameter for both short and long-term health monitoring. Assessing change in deflections could also simplify the assessment work for inspectors. Recent developments in digital camera technology and photogrammetry software enables point cloud with colour information (RGB values) to be generated. Thus, close range photogrammetry offers the potential of monitoring big and small-scale damages by point clouds. The current paper aims to monitor geometrical deviations in Pahtajokk Bridge, Northern Sweden, using an optical data acquisition technique. The bridge in this study is scanned two times by almost one year a part. After point cloud generation the datasets were compared to detect geometrical deviations. First scanning was carried out by both close range photogrammetry (CRP) and terrestrial laser scanning (TLS), while second scanning was performed by CRP only. Analyzing the results has shown the potential of CRP in bridge inspection.

  • 3446.
    Mirzazade, Ali
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. SINTEF Narvik AS, Narvik, 8517, Norway .
    Popescu, Cosmin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. SINTEF Narvik AS, Narvik, 8517, Norway .
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Predicting strains in embedded reinforcement based on surface deformation obtained by digital image correlation technique2021Inngår i: IABSE Congress Ghent 2021: Structural Engineering for Future Societal Needs / [ed] H. H. (Bert) Snijder; Bart De Pauw; Sander van Alphen; Pierre Mengeot, International Association for Bridge and Structural Engineering (IABSE) , 2021, s. 425-434Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This study is carried out to assess the applicability of using a digital image correlation (DIC) system in structural inspection, leading to deploy innovative instruments for strain/stress estimation along embedded rebars. A semi-empirical equation is proposed to predict the strain in embedded rebars as a function of surface strain in RC members. The proposed equation is validated by monitoring the surface strain in ten concrete tensile members, which are instrumented by strain gauges along the internal steel rebar. One advantage with this proposed model is the possibility to predict the local strain along the rebar, unlike previous models that only monitored average strain on the rebar. The results show the feasibility of strain prediction in embedded reinforcement using surface strain obtained by DIC.

  • 3447.
    Mirzazade, Ali
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Popescu, Cosmin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. SINTEF Narvik AS, 8517 Narvik, Norway.
    Gonzalez-Libreros, Jaime
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Sas, Gabriel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Semi-autonomous inspection for concrete structures using digital models and a hybrid approach based on deep learning and photogrammetry2023Inngår i: Journal of Civil Structural Health Monitoring, ISSN 2190-5452Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bridge inspections are relied heavily on visual inspection, and usually conducted within limited time windows, typically at night, to minimize their impact on traffic. This makes it difficult to inspect every meter of the structure, especially for large-scale bridges with hard-to-access areas, which creates a risk of missing serious defects or even safety hazards. This paper presents a new technique for the semi-automated damage detection in tunnel linings and bridges using a hybrid approach based on photogrammetry and deep learning. The first approach involves using photogrammetry to reconstruct a 3D model. It is shown that a model with sub-centimeter accuracy can be obtained after noise removal. However, noise removal also reduces the point cloud density, making the 3D point cloud unsuitable for quantification of small-scale damages such as fine cracks. Therefore, the captured images are also analyzed using deep convolutional neural network (CNN) models to enable crack detection and segmentation. For this aim, in the second approach, the 3D model is generated by the output of CNN models to enable crack localization and quantification on 3D digital model. These two approaches were evaluated in separate case studies, showing that the proposed technique could be a valuable tool to assist human inspectors in detecting, localizing, and quantifying defects on concrete structures.

    Fulltekst (pdf)
    fulltext
  • 3448.
    Moberg, Elias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för samhällsbyggnad och industriell teknik, Industriell teknik.
    The value of flexibility in a future electric power distribution system2021Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The size and composition of the Swedish electricity generation are changing. This, in combination with new legal requirements from regulatory entities including the EU Directive 2019/944, creates several challenges for the design of the future system. Among other things, the directive suggests that flexibility solutions are to be integrated into grids to increase the degree of utilization and avoid congestions, when socio-economically profitable. This thesis evaluates what this could mean in a Swedish context, in combination with providing a basic understanding of the contradictions that can arise between a desired efficient grid use in an energy system that goes towards more distributed and intermittent energy generation sources.

    The work is carried out in collaboration with Vattenfall Eldistribution AB, focusing on the geographical area of Uppsala and Stockholm, the Swedish region hit hardest by local congestions. The work assumes that the economic value of a flexibility solution is at most equivalent to the cost of a conventional new construction aimed at capacity strengthening, or the Value of Lost Load (VoLL). The report’s most important deliverable is a model based on this view. The model is used to evaluate the economic value of flexibility per kWh, in three regional grid construction projects within the mentioned region. 

    The results show that there is a great potential for using flexibility resources to increase utilization in grids and also to optimize the costs that society pays for this infrastructure by such methods. However, the work concludes that the usage of flexible technologies primarily is to adapt electric consumption with intermittent energy generation, rather than being used to solve local grid capacity shortages.

    Fulltekst (pdf)
    fulltext
  • 3449.
    Moen, Olof
    Göteborgs Universitet.
    Femstegsmodellen: affärsmodell med ruttoptimering för ökad transporteffektivitet vid urbana godstransporter2016Rapport (Annet vitenskapelig)
    Abstract [sv]

    Urbana godstransporter har under de senaste åren hamnat allt mer i fokus genom deras upplevda negativa påverkan på stadsmiljön samt utsläpp av växthusgaser och hälsofarliga emissioner. För att nå miljömål samt öka våra städers attraktivitet krävs en ny inriktning i utvecklingen av transportsystemet, en utveckling mot ett mer transportsnålt samhälle där effektivare godstransporter i stadsmiljö är en del av lösningen. Den ökade urbaniseringen och förtätningen av städer ställer nya krav på urbana godstransporter. Ökad effektivitet och resursoptimerade transporter blir en förutsättning för en framtida fungerande stad. Dagens utmaning med ökande trängsel och låga fyllnadsgrader för godstrafiken måste på sikt lösas. Femstegsmodellen är en vidareutveckling av kommunal samordnad varudistribution som ökar fyllnadsgraden, minskar antal körda kilometer och ger färre distributionsbilar för samma mängd gods. Konceptet har i denna studie överförts och testats på en privat aktör. Det unika med Femstegsmodellen är att den fokuserar på att styra godstransporterna redan i upphandlingsskedet och använder ruttoptimering som verktyg för att öka energieffektiviteten. Rätt använd kan modellen ge betydande samhällsekonomiska vinster samtidigt som den ger kostnadsbesparingar för transportköpare och ökad lönsamhet i transportörsledet. Studien har utarbetats inom ramen för Trafikverkets FoI-verksamhet och för innehållet svarar författaren, databearbetning och simuleringar med ruttoptimering har utförts av Daniel Moback (WSP Analys & Strategi).

    Fulltekst (pdf)
    FULLTEXT01
    Fulltekst (jpg)
    Omslagsbild
  • 3450.
    Moghtadernejad, Saviz
    et al.
    Swiss Fed Inst Technol, Inst Construct & Infrastruct Management, Eidgenoss TH, CH-8093 Zurich, Switzerland..
    Jin, Yuchuan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE). Royal Inst Technol, Kungliga Tekniskahogskolan KTH, Div Transport Planning, S-11428 Stockholm, Sweden..
    Adey, Bryan Tyrone
    Swiss Fed Inst Technol, Inst Construct & Infrastruct Management, Eidgenoss TH, CH-8093 Zurich, Switzerland..
    Estimating the Values of Missing Data Related to Infrastructure Condition States Using Their Spatial Correlation2023Inngår i: Journal of Infrastructure Systems, ISSN 1076-0342, E-ISSN 1943-555X, Vol. 29, nr 1, artikkel-id 04022041Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Infrastructure managers consistently monitor the condition of their assets to predict their deterioration speed and determine the optimal time to execute preventive interventions. However, despite the recent progress in more frequent and accurate monitoring of assets and storage of the related results, in practice, real-world data often contains errors and discrepancies such as missing data or faulty entries. This problem can happen owing to collection errors during routine inspections or inconsistency of data storage formats in different years. Because the quality of data plays a significant role in the accuracy of deterioration prediction and the resulting intervention programs, it is important to improve condition state predictions by imputing the values of missing information. This paper examines the efficiency of different models that use the spatial correlation of infrastructure assets in predicting the value of missing data. The models include univariate and multivariate Kriging, a hybrid artificial neural network (ANN)-Kriging model, and the bidirectional long short term memory (bi-LSTM) neural network, which can model the data with spatial correlation or a sequential relationship. The results confirm that the condition indicator values can be estimated with reasonably low levels of error.

66676869707172 3401 - 3450 of 5875
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf