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  • 51.
    Coric, Ibrahim
    et al.
    Trafikverket.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. Skanska Sverige.
    Sas, Gabriel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. Norut, Norge.
    Ohlsson, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Railway Bridges on the Iron Ore Line in Northern Sweden– From Axle Loads of 14 to 32,5 ton2018Inngår i: IABSE Conference 2018 – Engineering the Past, to Meet the Needs of the FutureJune 25-27 2018, Copenhagen, Denmark: IABSE Reports, Vol 111, 2018, Vol. 111Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Iron Ore Railway Line was built around 1900 and has more than 100 bridges. It has a length of ca 500 km and runs from Kiruna and Malmberget in northern Sweden to the ice-free harbour in Narvik in Norway on the Atlantic and to Luleå in Sweden on the Baltic. The original axle load was 14 ton. The axle load has gradually been increased to 25 ton in 1955, to 30 ton in 1998 and to 32,5 ton in 2017.The increases in axle loads have been preceded by monitoring and assessment studies of the bridges. The capacity and need for strengthening or replacement of the bridges have been evaluated. Many of the bridges could carry a higher load than what it was designed for. Experiences from studies before the axle load was increased in 1998 and 2017 are presented and discussed.

  • 52.
    Crabtree Gärdin, David
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Jimenez, Alexander
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Optical methods for 3D-reconstruction of railway bridges: Infrared scanning, Close range photogrammetry and Terrestrial laser scanning2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The forecast of the next upcoming years estimates a growth of demand in transport. As the railway sector in Europe has developed over many years, the infrastructure presents performance issues because of, among other factors, asset maintenance activities being difficult and time consuming. There are currently 4000 railway bridges in Sweden managed by Trafikverket which are submitted to inspections at least every six years. The most common survey is done visually to determine the physical and functional condition of the bridges as well as finding damages that may exist on them. Because visual inspection is a subjective evaluation technique, the results of these bridge inspections may vary from inspector to inspector. The data collection is time consuming and written in standard inspection reports which may not provide sufficient visualization of damages. The inspector also needs to move around the bridge at close distance which could lead to unsafe working conditions.

    3D modelling technology is becoming more and more common. Methods such as Close Ranged Photogrammetry (CRP) and Terrestrial Laser Scanning (TLS) are starting to be used for architecture and heritage preservation as well as engineering applications. Infrared (IR) scanning is also showing potential in creating 3D models but has yet not been used for structural analysis and inspections. A result from these methods is a point cloud, a 3D representation of a model in points that can be used for creating as-built Building Information Modeling (BIM)-models.

    In this study, the authors put these three methods to test to see if IR scanning and CRP are suitable ways, such as TLS is, to gather data for 3D-reconstruction of concrete railway bridges in fast, safe and non-disturbing ways. For this, the three technologies are performed on six bridges chosen by Trafikverket. The further aim is to determine if the 3D-reconstructions can be used for acquiring BIM-information to, among other things, create as-built drawings and to perform structural evaluations.

    As a result from the study, IR scanning and CRP show great potential as well as TLS in 3D-reconstruction of concrete railway bridges in fast, safe and non-disturbing ways. Still, there is a need of development regarding the technologies before we can start to rely on them completely.

  • 53.
    Cremona, Christian
    et al.
    Laboratoire Central des Ponts et Chaussées, Paris, France.
    Patron, A
    LCPC, Paris, France.
    Johansson, Bernt
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. Luleå University of Technology, Sweden.
    Larsson, Tobias
    Luleå University of Technology, Sweden.
    Eichler, B
    RWTH, Aachen, Germany.
    Höhler, S
    RWTH, Aachen, Germany.
    Kühn, B
    PSP, Aachen, Germany.
    Improved Assessment Methods for Static and Fatigue Resistance of Old Steel Railway Bridges: Sustainable Bridges Background document D4.62007Rapport (Fagfellevurdert)
    Abstract [en]

    The report is divided into four parts related to the four research activities of the WP4 metal subgroup:

    – Analysis of material properties of existing metal railway bridges,

    – Fatigue of riveted structure,

    – Updated assessment methods for riveted structures,

    – Enhanced non destructive techniques for inspecting riveted structures.

  • 54.
    Cwirzen, Andrzej
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Metsäpelto, Lari
    MSc, YIT Infra Oy, Helsinki, Finland.
    Habermehl-Cwirzen, Karin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Interaction of Magnesia with Limestone-Metakaolin-Calcium Hydroxide Ternary Alkali-Activated Systems2018Inngår i: Advances in Materials Science and Engineering, ISSN 1687-8434, E-ISSN 1687-8442, Vol. 2018, artikkel-id 1249615Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of magnesia on ternary systems composed of limestone, metakaolin and calcium hydroxide, alkali activated with sodium silicate, sodium hydroxide, and sodium sulphate was studied by determination of the compressive strength, X-ray powder diffraction (XRD), thermogravimetry (TG), and scanning electron microscope (SEM). Pastes activated with sodium silicate and sodium sulphate showed strength regression caused by a formation of an unstable prone to cracking geopolymer gel. The presence of magnesia in sodium hydroxide-activated system hindered this trend by promoting a formation of more stable crystalline phases intermixed with brucide. In general, magnesia densified the binder matrix by promoting a formation of amorphous phases while sodium hydroxide produced the most porous microstructure containing high amount of crystalline phases.

  • 55.
    de Dardel, Felix
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Brandskydd efter tid - Uppfylls funktionen av brandskyddsinstallationer efter tid de krav som förutsätts vid nybyggnation?2019Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Nya byggnader konstrueras och uppförs dagligen i Sverige. Då utvecklingen går framåt blir personer mer specificerade inom olika byggnadstekniska områden och tidsramarna för byggnation blir allt stramare. När byggnaderna är färdigkonstruerade övergår byggnationsskedet till förvaltningsskede och underhållet samt kontrollen av brandskyddet i byggnaden överlämnas till de som äger alternativt nyttjar byggnaden. Därefter förväntas funktionerna i brandskyddet fortsätta att stå i paritet med det som ursprungligen projekterats genom ett systematiskt brandskyddsarbete.

    Examensarbetet syftar till att undersöka om funktionen av de ingående brandskyddsinstallationerna uppfyller de krav som de ursprungligen projekterats för. Detta kontrollerades genom att sju platsbesök genomfördes, samt att sex brandskyddsdokumentationer och åtta inventeringsdokument inhämtades. Utifrån dessa underlag kunde urval om brandskyddstekniska installationer urskiljas och granskas mer ingående.

    Resultatet av studien visar att totalt 17 specifika brister, som beror på åldring eller användning av byggnaden, kunde identifieras i de totalt åtta behandlade fastigheterna. Det innebär ett snitt på över två specifika brister per fastighet. Studien ger en indikation på att brister i funktioner av brandskyddet är förekommande efter tid.

    Att brister i brandskyddets funktioner uppkommer bidrar till att brand kan ske i ökad omfattning och ett snabbare brandförlopp. Det här kan i sin tur ge förödande konsekvenser för både personer och egendom.

    Orsakerna till försämringen kan bero på många faktorer. Förlorad information mellan olika byggskeden, bristfällig dokumentation samt att funktionalitet prioriteras över brandskydd är endast några faktorer som identifierats vara bidragande till denna utveckling.

  • 56.
    Dogar, Attiq Ur Rahman
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Post Elastic Behaviour and Moment Redistribution in a Double Span LTP200 Steel Trapezoidal Sheet2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
  • 57. Dury, Robin
    et al.
    Bernander, Stig
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Kullingsjö, Anders
    Skanska Teknik AB.
    Laue, Jan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Pusch, Roland
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Progressive Landslide Analysis with Bernander Finite Difference Method2017Inngår i: / [ed] Vikas Thakur, Jean-Sébastien L’Heureux, Ariane Locat, 2017, s. 1-Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The poster presents a new Spreadsheet developed by Robin Dury (2017) to simplify the use of the Finite Difference Method developed by Stig Bernander et al (2011, 2016).

    It includes:

    - Material Properties

    - Finite Difference Method

    - Progressive failure process with five phses

    - Discussion

    - References

  • 58.
    Duvnjak, Ivan
    et al.
    University of Zagreb, Croatia.
    Bartolak, Marko
    University of Croatia.
    Nilimaa, Jonny
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Sas, Gabriel
    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.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Lessons Learnt from Full-Scale Tests of Bridges in Croatia and Sweden2018Inngår i: IABSE Symposium, Nantes 2018: Tomorrow's Megastructures, International Association for Bridge and Structural Engineering , 2018, artikkel-id S23-127Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Load testing is a way to control the capacity and function of a bridge. Methods and recommendations for load testing are described and examples are given form tests carried out in Croatia and Sweden. In order not to damage the bridge being tested, the load must be limited, often to be within the serviceability limit state (SLS). Numerical models can be calibrated by load tests and then be used to check the carrying capacity for higher loads than what has been tested. Need for further work and recommendations are discussed. By effective planning, costs can be saved and a more sustainable use of bridges can be obtained.

  • 59.
    Duvnjak, Ivan
    et al.
    University of Zagreb, Croatia.
    Damjanović, Domagoj
    University of Zagreb, Croatia.
    Sabourova, Natalia
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Grip, Niklas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Ohlsson, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Tu, Yongming
    School of Civil Engineering, Southeast University, Nanjing, China.
    Damage Detection in Structures – Examples2019Inngår i: IABSE Symposium 2019: Towards a Resilent Built Environment - Risk and Asset Management, 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Damage assessment of structures includes estimation of location and severity of damage. Quite often it is done by using changes of dynamic properties, such as natural frequencies, mode shapes and damping ratios, determined on undamaged and damaged structures. The basic principle is to use dynamic properties of a structure as indicators of any change of its stiffness and/or mass. In this paper, two new methods for damage detection are presented and compared. The first method is based on comparison of normalised modal shape vectors determined before and after damage. The second method uses so-called 𝑙1-norm regularized finite element model updating. Some important properties of these methods are demonstrated using simulations on a Kirchhoff plate. The pros and cons of the two methods are discussed. Unique aspects of the methods are highlighted.

  • 60.
    Eberius, Catrin
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Fjällström, Kristin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    The impact of fire development on design resistance of structures2017Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The current design methods used to determine fire progression and temperature-time development in fire compartments today are being questioned to not give accurate results in large and complex enclosures (larger than 500 m2). The established design methods proposed by Eurocode and used by fire safety engineers today are primarily the standard temperature-time curve and the parametric temperature-time curves. The parametric temperature-time curves are based on the heat and mass balance equations and both methods assume homogenous temperatures and uniform burning. These assumptions are being questioned for use in large enclosures such as open-plan compartments and compartments with multiple floors connected which are typically modern and common building types in today’s society.

    Today there are no established design methods developed to determine fire progression in large enclosures, but the Improved Travelling Fire Method (iTFM) and the New MT model II are new, alternative design methods which are prospects to become established engineering tools in the future. The iTFM is developed at the University of Edinburgh for travelling fires in large size compartments and the New MT model II is developed by RISE, Research Institutes of Sweden, for large tunnel fires. These two new design methods have been investigated and compared to established methods in a case study. Also localised fires from Eurocode with proposed interpretations by Ulf Wickström has been investigated and compared to the standard temperature-time curve and the parametric temperature-time curves. The new interpretation suggests that the given heat flux boundary conditions in Eurocode are interpreted as adiabatic surface temperatures based on given emissivities and convection heat transfer coefficients according to Eurocode.

    Through a case study the different methods were compared throughout reference buildings with constant material properties and fire loads, but with varying floor area and height. The result focused on if the new methods have more bearing on reality than the standard fire curve and the parametric temperature-time curves methods when determining fire progression and temperature-time development. Desired benefits with the new methods are to better predict and describe fire development in large enclosures. The referenceIIIbuildings were considered as occupancy class 2 (Vk2) and Br2 buildings with a load bearing fire resistance capacity demand of 30 minutes. This report is an early stage in the process of developing new fire models to improve the fire designing process when working with large compartments. The aim with the new, alternative methods and localised fires with proposed interpretation is to enable them to become engineering tools used by fire safety engineers in the future to create a more efficient and adapted design process.

    The results differ significantly depending on used method and reference building. The maximum temperatures conducted by the iTFM are in general higher than the standard fire curve and the parametric temperature-time curves. When applying the method to the reference building with high ceiling height and low spread rate the resulting temperatures were lower than the standard fire curve. The fire progression of the New MT model II is highly dependent on opening factor and time until temperature increase starts. In comparison to the parametric fire curves with the same opening factors the New MT model II resulted in considerably faster temperature development and higher temperatures. Localised fires with the new proposed interpretations resulted in adiabatic surface temperatures which were compared to the standard temperature-time curve after 30 minutes of fire and the maximum temperature of the parametric temperature-time curves. The comparison resulted in slightly lower temperatures for the localised fires with the new proposed interpretations compared to the standard temperature-time curve and similar temperatures compared to the parametric temperature-time curves in the case study.

    The results of the iTFM and the New MT model II differs significantly depending on physical parameters used in the calculation processes. The models are customizable and vary depending on fire scenarios and compartments and could possibly be future alternative methods when designing for fires in large compartments. Further studies and development together with real fire tests would provide the models with better accuracy and continuity. Localised fires with proposed new interpretations are a future prospect to become a future standard method for determination of maximum temperature of member surfaces in fire safety design.

  • 61.
    Edin, Erik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Ström, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Comparing a full scale test with FDS, FireFOAM, McCaffrey & Eurocode2019Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    In the rapidly growing field of CFD-calculations (Computational Fluid Dynamics), companies and organizations are bringing forth new tools, tools that display an image of a given fire scenario. These tools are developed because they provide time efficiency as well as a sustainable economic approach. Another useful tool is analytical solutions, these analytical solutions serve the same purpose as CFD-modeling, providing results of a given scenario. The purpose of this thesis was to simulate a fire plume with two different CFDprograms and compare the gas temperature from each simulation with a full-scale test. Also, analytical solutions were used to perform the same comparisons. Four different calculation models were utilized to obtain results. The CFD-programs were FDS (Fire Dynamics Simulator) and FireFOAM. The analytical solutions were performed using McCaffrey´s plume equation and Eurocode solutions for localized fire temperatures. FDS is a very well documented program, due to this, problems that arose were easily fixed. The structure of FDS enables the user to maneuver the program easily. SmokeView was used to visualize the simulation. FireFOAM is written in C++ and is operated through the command prompt. The structure of the program was time-consuming to understand mainly because of two reasons, primarily because the authors lack of knowledge in coding in C++, and second because of the LINUX environment. Moreover, the process of working in FireFOAM was mostly through trial and error. On some occasions, issues arose that could be solved by communication with other CFD users at CFD-Online. When major problems occurred, regarding the code or other CFD issues, Johan Anderson at RISE Research Institutes of Sweden guided us through most of these problems and enabled us to move forward with the work. ParaView was used to visualize the simulation, and Excel was used to evaluate the temperature data from the FDS- and FireFOAM simulations. For the calculations in FDS and FireFOAM, a sensitivity analysis was performed to see which grid size presented best results in each program. A grid size of 5 cm, 10 cm, and 20 cm were applied in FDS, and in FireFOAM the grid dimensions were set to 5 cm and 10 cm. The results showed that 5 cm was the most appropriate grid size for both programs. It would have been more favorably to simulate with several different grid sizes, to further strengthen the grid analysis. Though, due to the time frame of the thesis, further simulations were not performed. Calculations were repeated for the same scenario only with a lower HRR (Heat release rate). An extensive sensitivity analysis was conducted for FDS in the form of two different simulations. One simulation where HRR was the same as the full-scale test but with twice the area of the burner. In the second simulation, the same area was used on the burner as the fullscale test, but with half the HRR. Results from the analytical solutions were easy to achieve; however, the model has some limitations regarding calculations within the flame region. The estimated gas temperature, using FDS, aligns well with the full-scale test. The temperatures analyzed from FireFOAM deviated in general through the flame region and reached unreasonable high temperatures close to the ceiling. Since the analytical solutions were based on different conditions compared to those applied in the full-scale test, it was expected that the results should deviate. However, McCaffrey plume equations can still be used to give an approximate picture of scenarios similar to that of the full-scale test, and the same applies to Eurocode solutions for localized fire temperatures. Analysis of the results shows that FDS can be used to simulate similar scenarios. FireFOAM simulates a gas temperature that is overestimated within the flame region. One of the reasons for this was due to the grid size since the sensitivity analysis III showed that a refined grid size resulted in more correct temperature value, the reason for not simulating with a more refined grid size was due to the restricted time frame of this thesis. FireFOAM is, at present, recommended for researchers who wish to use the code for specific purposes. Therefore, given the same premises, FireFOAM is not recommended for the standard fire safety analysis.

  • 62.
    Edrees, Tarek
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Identification of building damage using armax model: A parametric study2016Inngår i: Diagnostyka, ISSN 1641-6414, Vol. 17, nr 3, s. 3-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Structural Identification approach is used to identify and localize the existence of damage for a steel frame. The black box linear parametric model called Auto-Regressive Moving Average with eXternal input (ARMAX) was utilized for the construction of the Frequency Response Functions, based on simulation results. The Singular Value Decomposition method was adopted to identify how many significant eigenvalues exist and plot the Complex Mode Indicator Function for the complete frame. Three damage indices were adopted to evaluate the state of damage in the frame. The results indicated that the ARMAX is a robust scheme for structural damage detection.

  • 63.
    Edrees, Tarek
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. College of Engineering, Department of Civil Engineering, University of Mosul, Mosul, Iraq.
    Nikolakopoulos, George
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Dritsas, Leonidas
    University of Patras, Department of Electrical Engineering.
    Semi-active control of flexible structures using closed-loop input shaping techniques2017Inngår i: Structural Control and Health Monitoring: The Bulletin of ACS, ISSN 1545-2255, E-ISSN 1545-2263, Vol. 24, nr 5, artikkel-id e1913Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this research effort, a novel approach on the control of structures with magnetorheological (MR) dampers is presented, based on an appropriately adapted closed-loop version of the generic input shaping control theory. The MR damper is a very promising kind of semi-active control system (actuator), mixing the advantages of the active and passive structural control systems, hence their increasing use as attenuators that reject the effects of dynamic loads on civil engineering structures. The main contribution of this article is the application and performance evaluation of the novel ‘Linear Matrix Inequality-based’ feedback version of the input shaping control theory for the first time in the area of structural control. The need for the use of a feedback version of input shaping control stems from the design trade-off between robustness and speed of response requirements. A simulation of a benchmark three-story building with one MR damper is employed to verify the efficiency of the proposed control approach. The nonlinear behaviour of the MR damper, rigidly connected between the first floor of the structure and the ground, is captured by the well-known Bouc–Wen model. The superiority and effectiveness of the proposed scheme in reducing the responses of the structure were proved using seven quantifiable evaluation criteria and by comparing these results with those achieved by classical and well-established alternative control schemes.

  • 64.
    Ek, Niklas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Andersson, Isac
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Temperature distribution and charring penetrations in timber assemblies exposed to parametric fire curves: Comparisons between tests and TASEF predictions2017Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    Four furnace tests have been performed using two different parametric fire curves and the results are compared with computer simulations and Eurocode calculations. What differentiates the parametric fire curve from other fire curves is in particular the cooling phase, something that has proven to be hard to model for timber structures.

     

    A literature study and computer simulations were followed by experimental work performed at SP Wood Building Technology in Stockholm. The computer simulations were performed using the computer code TASEF. The predictions from TASEF were compared with measurements from the fire tests to evaluate how well the program can predict temperature distribution using a parametric fire curve.

     

    The four fire tests were executed at SP Wood Building Technology, glued laminated timber beams were used in all tests. When preparing the test specimens thermocouples were installed to measure temperature distribution, the thermocouples were installed in drilled holes. A deviation study regarding these drill-holes was performed as a part of the preparations. The temperature distributions measured during the tests were compared with the temperature distribution predicted by TASEF.

     

    Charring rate and charring depth were obtained from the fire tests, from the TASEF simulations but also by using equations given in the Eurocode. Since TASEF simulates temperature distribution and not charring depth, the 300 °C isotherm was assumed to represent the charring depth. The results from all three methods were compared and evaluated.

     

    The agreement between experiments and TASEF predictions regarding temperature distribution and charring depth were in general very good. Parametric fire curves with opening factors of 0.02 m1/2 and 0.04 m1/2 were used in four fire tests. TASEF performed more accurate predictions regarding the temperature distribution for the small opening factor but looking at the charring depth the predictions were better for the bigger opening factor. It is recommended to perform further studies and find out the reason for this behaviour.

     

    Comparing the charring depths measured at the tests with values calculated using Eurocode 5 there were some differences in charring depths. Charring depths for the horizontal direction of the beams were much alike, but when comparing the charring depths for the vertical direction there is a significant difference. The equations regarding charring depth for wood exposed to parametric fire curves in Eurocode 5 underestimate the charring depth. It is recommended to evaluate these equations further.

     

    For one of the timber beams delamination occurred, this has previously been assumed not to occur to glued laminated beams. More studies should be performed regarding delamination of glued laminated beams exposed to fire.

  • 65.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Activity: Bridge Design, K7005B2015Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 66.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Aktivitet: Högpresterande betong ger lättare konstruktioner1992Annet (Annet (populærvitenskap, debatt, mm))
  • 67.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Aktivitet: Kompetenscentra behövs. Goda erfarenheter av tvärdisciplinär forskning i Luleå1992Annet (Annet (populærvitenskap, debatt, mm))
  • 68.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Avdelningen för Konstruktionsteknik. Verksamhetsberättelse 1983/841984Rapport (Annet (populærvitenskap, debatt, mm))
  • 69.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Avdelningen för Konstruktionsteknik. Verksamhetsberättelse 1984/851985Rapport (Annet (populærvitenskap, debatt, mm))
  • 70.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Discussion of “Failure Load Test of a CFRP Strengthened Railway Bridge in Örnsköldsvik, Sweden” by Marcus Bergström, Björn Täljsten, and Anders Carolin2011Inngår i: Journal of Bridge Engineering, ISSN 1084-0702, E-ISSN 1943-5592, Vol. 16, nr 3, s. 490-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The authors have written an interesting paper on the test to failure of a strengthened railway bridge. However, the failure mode analysis of the bridge as built is not correct. The failure mode is the same for the bridge as built as for the strengthened bridge, i.e., crushing of the compression concrete with yielding of the steel in tension. For the strengthened bridge, bond failure of the carbon-fiber-reinforced polymer (CFRP)reinforcement also played an important part in the initiation of the final collapse. Eq. (1) in the original paper underestimates the bending moment capacity M1 of the bridge as built almost by a factor of 2 as loading up to crushing of the concrete was not considered. Instead, Eq. (8) should have been used with a zero contribution from strengthening. In Eq. (8) there is also a printing error as the coefficient β2 is left out in the last parentheses (it should read “h - β2x2” instead of “h - 2”). The underestimation of the capacity of the bridge as built gives erroneous results in Table 2 and in Fig. 5. In Table 2 the height x1 of the compression zone for the bridge as built should be about half the given value of 291 mm. The value M1 corresponding to the bridge as built should be about twice the given value of 4.5 MN. The given flexural capacities M1 and M2, of the as built and strengthened bridges, respectively, refer to the corresponding applied vertical load P causing the flexural moments and not to the moments themselves. This explains why the unit MN is used instead of MN·m. Furthermore, the shear capacity V also refers to the corresponding applied vertical load P causing the shear and not to the shear capacity itself (which is about half the value of the applied load P). Furthermore, in Table 2 the comment to the shear capacity V should be referring to Eq. (11) instead of to Eq. (6). In Fig. 5, all the load values refer to the values of the applied load P causing the shear and flexure;  not to the moments M1 and M2 or to the shear force T. After the corrections mentioned previously, the values corresponding to the two moments M1 and M2 will be located much closer to each other. 

    The corrections do not change the main conclusions of the paper, and the discusser agrees with the authors that the tested bridge gives a good example of the complex interaction of bending and shear in concrete bridges. Additional information about the test and the different analysis of it and the European Research Project, which it was a part of, can be found in Elfgren et al. (2008), Puurula et al. (2008), Feltrin et al. (2008), Helmerich et al. (2008), Jensen et al. (2008), Täljsten et al. (2008), and Sustainable Bridges (2008).

  • 71.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Maskinfundament: Beräkning av egensvängningar1984Annet (Annet vitenskapelig)
    Abstract [sv]

    En metod presenteras för att beräkna translations- och translationssvängningar för maskinfundament av betong. Metoden illustreras med ett beräkningsexempel.

  • 72.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Notiser.  Hallå där... om Internationella Broföreningens kongress i Stockholm 20162016Inngår i: Cementa, ISSN 0346-8771, nr 3, s. 5-Artikkel, omtale (Annet (populærvitenskap, debatt, mm))
  • 73.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Projekt: Sveriges Bygguniversitet2012Annet (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    En samverkan mellan de tekniska högskolar i Sverige som utbildar civilingenjörer i samhällsbyggnad / väg- och vattenbyggnad, dvs i första hand Lunds tekniska högskola, LTH, Chalmers tekniska högskola, Kungliga tekniska högskolan, KTH, och Luleå tekniska universitet, LTU)

  • 74.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Bernander, Stig
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Knutsson, Sven ()
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Response to and Comments on “Geotechnical Peer Review of Dr. S. Bernander’s Reports and Analysis of the North Spur”2018Rapport (Annet vitenskapelig)
    Abstract [en]

    The concerns regarding the stability of the North Spur can be summarized in three points:

    (1) None of the most critical inclined failure surfaces have been studied by Muskrat Falls Corporation. These failure surfaces may be initiated on the upstream side of the dam containment. Here the effects of the deformations, caused by the pressure of the rising water level, have to be resisted by the metastable soil layers in the North Spur. A local failure may occur progressing downwards towards the downstream side of the Spur. A catastrophic dam breach would follow. The GPRP further categorically overlooks the fact that horizontal failure planes cannot possibly represent the highest risk of instability irrespective of whether the analysis is based on the Limit Equilibrium Mode (LEM) or on the Progressive Failure Mode.

    (2) The stress/strain deformation properties of the porous soils in the North Spur have not been made available. Only strength properties, related to fully drained conditions, have been given. How stresses relate to simultaneous deformations under undrained (or partially undrained) conditions have not been defined in any way. Such relationships are crucially essential for any up-to-date analysis of slope stability.

    (3) A high risk of North Spur instability has been found related to impoundment.  A series of investigatory calculations have been made, based on deformation properties from similar landslides and on a wide variety of assumed input data for possible critical failure surfaces. The results of these analyses indicated a safety factor far below 1.

    The peer review does not address the above three points. It gives a good view of the general conditions but also contains misconceptions, erroneous considerations and refutable comments indicating that the earlier reports by Bernander have not been fully understood by the panel members.

    As no up-to-date analysis of the stability of the North Spur has been provided, our conclusion is that an independent group of experts, appointed by government, should be entrusted with this important task.

  • 75.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Nilimaa, Jonny
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Project: Mainline-MAINtenance, renewaL and Improvement of rail transport iNfrastructure to reduce Economic and environmental impacts2012Annet (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    - Apply new technologies to extend the life of elderly infrastructure - Improve degradation and structural models to develop more realistic life cycle cost and safety models - Investigate new construction methods for the replacement of obsolete infrastructure- Investigate monitoring techniques to complement or replace existing examination techniques -Develop management tools to assess whole life environmental and economic impact.

  • 76.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Emborg, Mats
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Elsa och Sven Thysells Stiftelse för konstruktionsteknisk forskning inom väg och vatten vid Luleå tekniska universitet: En skrift tillägnad Donator Sven Thysell på 100-årsdagen 2016-09-022016Rapport (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    Denna skrift ger en kort beskrivning av Elsa och Sven Thysells stiftelse för konstruktionsteknisk forskning inom väg- och vatten vid Luleå tekniska universitet. Skriften har sammanställts inför donator Sven Thysells 100-årsdag den 2 september 2016. Vi är mycket tacksamma för det stöd Stiftelsen har gett och ger till konstruktionsteknisk forskning vid LTU. Stödet betyder mycket för att vår verksamhet skall kunna utvecklas till nytta för samhället

  • 77.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Enochsson, Ola
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Thun, Håkan
    Project: Sustainable Bridges2013Annet (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    Ett EU-projekt med avsikt att förlänga livlängden för befinmtliga järnvägsbroar

  • 78.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Fransson, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser. Skanska Teknik AB.
    Infrastructure in NW Russia - Potential development: A Pre-feasibility Study with Special Reference to Winter Transportation, Concrete Structures, and Timber Structures 2000Rapport (Annet vitenskapelig)
    Abstract [en]

    In co-operation with a Finnish Group of researchers a pre-feasibility study was undertaken regarding potential development of the Infrastructure in NW Russia. Special emphasis was given: Winter Transportation and Reinforcement of Load Bearing Ice Covers; Concrete Construction and Strengthening of Concrete Structures; Timber Construction and Mechanical Wood Industry Development; and Energy Conservation and Industrial Energy Development.

    Based on the study three Russian-Swedish co-operation projects have started:

    - Load Bearing Ice Covers (Literature Survey)

    - Forces caused by Ice Crushing against Off-Shore Structures (EC funded Research Project)

    - Strengthening of a Bridge. Co-operation Stabilator/Skanska - Arkhangelsk Road

  • 79.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Grennberg, Torsten
    Luleå tekniska universitet.
    Horrigmoe, Geir
    Luleå tekniska universitet.
    Axelsson, Kennet B. E.
    Högskolan i Luleå, Luleå tekniska universitet, Luleå University of Technology.
    Johansson, Bernt
    Institutionen för Anläggningsteknik. Verksamhetsberättelse 1986/871987Rapport (Annet (populærvitenskap, debatt, mm))
  • 80.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Horrigmoe, Geir
    Luleå tekniska universitet.
    Grennberg, Torsten
    Luleå tekniska universitet.
    Axelsson, Kennet B. E.
    Högskolan i Luleå, Luleå tekniska universitet, Luleå University of Technology.
    Johansson, Bernt
    Institutionen för Anläggningsteknik - Verksamhetsberättelse 1985/861986Rapport (Annet (populærvitenskap, debatt, mm))
  • 81.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Jonsson, JohanTrafikverket.Karlsson, Mats D.Trafikverket.Rydberg-Forssbäck, LahjaTrafikverket.Sigfrid, BrittTrafikverket.
    IABSE Congress Stockholm, 2016: Challenges in Design and Construction of an Innovative and Sustainable Built Environment2016Konferanseproceedings (Fagfellevurdert)
    Abstract [en]

    The conference aims to inspirre structural engineers and infrastructure managers to help forming and maintaing an innovative and sustainable built environment. The ernormous impact and long-time effect of the built environment motivates us to catch the opportunities that we have in front of us and help us ensure the best decisions by politicians and other decision makers.

    The proceeding contains 6 keynote presentations and more than 350 papers

  • 82.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Karlsson, Inge
    Chalmers tekniska högskola.
    Losberg, Anders
    Chalmers tekniska högskola.
    Torsion-Bending-Shear Interaction for Concrete Beams: Closure of discussion1976Inngår i: Journal of the Structural Division, Proceedings of tha American Society of civil Engineers, ASCE, ISSN 0733-9445, Vol. 102, nr ST1, s. 289-291, artikkel-id Proc. Paper 11819Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Closure to discussion by Solanki, Pandit and Helmy of paper in J of the Structural Division, ASCE, Vol 100, ST8, August 1974, pp 1657-1676

  • 83.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Karlsson, Lennart Å S
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Produkt- och produktionsutveckling. Tekniska fakultetsnämnden vid LuTH.
    Magnusson, Claes
    Tekniska fakultetsnämnden vid LuTH.
    Forskning och forskarutbildning vid Tekniska högskolan i Luleå: Strategisk Plan 1991-19951990Rapport (Fagfellevurdert)
    Abstract [sv]

    Forskningen vid Tekniska högskolan i Luleå syftar till att vinna ny kunskap inom områden som är betydelsfulla för landet och regionen. Forskarutbildningen syftar till att utbilda licentiater och doktorer inom sådana områden.

    Under femårsperioden fram till och med 1995 bör den externfinansierade forskningen öka med 25 %. Vidare bör 5-10 europeiskla samarbetsprojekt etableras. För att uppmå dessa mål bör programarbete genomföras inom bland annat områdena datateknik, teknik för kallt klimat, material- konstruktions- och produktionsteknik, kvinnor och teknik samt miljöteknik.

    En plan bör även upprättas för ny- och återanskaffning av utrustning.

    En doktorsexamen och en licentiatexamen bör avläggas per tvåårsperid i varje professorsämne. För att klara detta bör varje ämne ha minst tre aktiva forskarstuderande. De forskarstuderande bör erbjudas god handledning, ett bra utbud av doktorandkurser och en god akademisk miljö.

  • 84.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Linneberg, Poul
    COWI A/S, Lyngby, Denmark.
    Gudmundsson, Gudmundur Valur
    Vegagerdin - The Icelandic Road and coastal Administration.
    Leivo, Markku
    VTT Technical Research Centre of Finland.
    Köhler, Jochen
    Norwegian University of Science and Technology.
    Quality Control Plans for European Concrete Road Bridges: Experiences from Cooperation within COST Action TU 14062017Inngår i: Proceedings of the 23rd Nordic Concrete Research Symposium, Oslo, Norway, Oslo: Nordic Concrete Federation , 2017, s. 249-252Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The main objective of the COST Action TU1406 is to develop a guideline for the establishment of Quality Control plans for roadway bridges by integrating the most recent knowledge on performance assessment procedures. 36 European countries are working together in this endeavor during 2015-2019.

  • 85.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Nilforoush, Rasoul
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Nilsson, Martin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Ohlsson, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Assessment of Fasteners to Concrete: A Tribute to Rolf Eligehausen2017Inngår i: Connections between Steel and Concrete: 3rd International Symposium / [ed] Akanshu Sharma and Jan Hofmann, Stuttgart, 2017, s. 1294-1302Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Some examples are given of assessment of fastenings to concrete structures and the work started by Rolf Eligehausen in fib Task Group 2.9 “Fastenings to structural concrete and masonry”. Studies have been made on e.g. the influence of creep on adhesive anchors and of surface reinforcement and size effects on headed anchors.

  • 86.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Load Testing as Part of Bridge Management in Sweden.: Chapter 112019Inngår i: Load Testing of Bridges: Proof load Testing and the Future of Load Testing, Volume Editor Eva O. L. Landsoght: Series: Structures and Infrastructures, Vol. 13, Series Editor Dan M. Frangopol, / [ed] Eva O.L. Landsoght (Vol 13), Dan M. Frangopol (Series Editor), London/Leiden: Taylor and Francis Group , 2019, 1, s. 333-346Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Load testing of new and existing bridges was performed regularly in Sweden up to the 1960ies. It was then abandoned due to high costs versus little extra information obtained. Most bridges behaved well in the serviceability limit range and no knowledge of the ultimate limit stage could be obtained without destroying the bridge. At the same time the methods for calculating the capacity developed and new numerical methods were introduced. Detailed rules were given on how these methods should be used. Some decommissioned bridges were tested to their maximum capacity to be able to study their failure mechanisms and to calibrate the numerical methods. In this paper some examples are given on how allowable loads have increased over the years and of tests being performed. Nowadays, load testing may be on its way back, especially to test existing rural prestressed concrete bridges, where no design calculations have been retained

  • 87.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Sas, Gabriel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Nilimaa, Jonny
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Bagge, Niklas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. WSP, Luleå, Sweden.
    Tu, Yongming
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Puurula, Arto
    Savonia University of Applied Sciences, Kuopio.
    Häggström, Jens
    Trafikverket, Luleå, Sweden.
    Paulsson, Björn
    Charmec, Chalmers University of Technology.
    Load-testing used for qulity control of bridges2018Inngår i: Quality Specifications for Roadway Bridges: Workshop of COST TU 1406 / [ed] José Matos, 2018, s. 1-6Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Load testing is a way to control the capacity and function of a bridge. Methods and recommendations for load testing are described and examples are given form tests carried out. In order not to damage the bridge being tested, the load must be limited, often to be within the serviceability limit state (SLS). Numerical models can be calibrated by load tests and then be used to check the carrying capacity for higher loads than what has been tested. Need for further work and recommendations are discussed. By effective planning costs can be saved and a more sustainable use of bridges can be obtained.

  • 88.
    Elfgren, Lennart
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Veljkovic, Milan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Projekt: Centrum för riskanalys och riskhantering, CRR2012Annet (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    En centrumbildning vid LTU i samarbete med näringsliv och samhälle för studier av riskanalys och riskhantering

  • 89.
    Enochsson, Ola
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser. Bodens kommun, Sverige.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Johansson, Håkan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Ojanen, Johan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Emborg, Mats
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Tillståndsbedömning av järnvägsbro över Byske älv vid Myrheden, Bandelen Bastuträsk – Nyfors, km 1031+9372010Rapport (Fagfellevurdert)
    Abstract [sv]

    Järnvägsbron över Byske Älv vid Myrheden är en bågbro av betong som färdigställdes 1941. Bågen har en spännvidd av 39,2 m och den totala längden är 59,6 m. Bågen blev fläckvis frysskadad i samband med gjutningen och har reparerats med ca 10 års mellanrum. År 2003 upptäcktes ånyo betongskador i underkant på bågen. Den dåliga betongen bilades bort och ersattes med torrbruk som sprutades på plats. Efter reparationen bedömdes bron kunna klara tåglast BV-2 (25 tons axellast och 7,2 ton/m utbreddlast). För att bedöma brons fortsatta livslängd och bärförmåga har Avd för Byggkonstruktion vid LTU tagit del avtidigare tillståndsbedömningar och besiktigat bron 2009-02-13 och 2009-08-25--26. Bron visade sig vara i förhållandevis gott skick. Vi bedömer att den kan klara tåglast BV-2 i ytterligare fem år under förutsättning att den hålls under uppsikt och att en närmare utredninggörs av gjutfogarna i bågen under skivstöden och av skivstödens ledformade anslutningar mot bågen. Bron borde hålla i 20 år eller mer om ballasten rensas från finare grusfraktioner så att dräneringen förbättras. Vattenavledningen från bron bör vidare ordnas så att vatten från brobanan förhindras rinna ner längs bågen och bidra till frost- och korrosionsangrepp. Dessutom bör dålig/skadad betong vattenbilas bort och ersätts med pågjutning av ny betong.

  • 90.
    Eriksson, Petter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. 1992.
    Temperatursprickor i Ung Betong: Uppföljning av Den Svenska Sprickmodellen2017Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Då betong gjuts startar en serie av reaktioner mellan cementet och vattnet i betongen. Via dessa reaktioner hårdnar betongen och dess hållfasthet ökar. En produkt av reaktionerna är värme som avges inom konstruktionen. På så vis expanderar betongen samtidigt som hållfastheten ökar. Då betongen avsvalnar kontraherar den, samtidigt hålls konstruktionen fast av omkringliggande konstruktioner som kan vara en platta som aktuell konstruktion gjuts på. Detta mothåll kallas tvång som i sin tur skapar spänningar i det motgjutna elementet till följd av de mothållna rörelserna. Om dessa spänningar överskrider den aktuella draghållfastheten spricker betongen.

    De sprickor som uppstår till följd av spänningarna försämrar konstruktionens täthet, vilket kan leda till skador och förminskad livslängd och bärförmåga. För att minska risken för dessa sprickor införde Vägverket krav i BRO 94 som reglerade maximala spänningsnivåer till följd av spricksäkerhetsfaktorer och tre metoder att begränsa dessa sprickor. Detta är vad som kallas den svenska sprickmodellen. Det huvudsakliga syftet med arbetet har varit att utvärdera den svenska sprickmodellen, sett främst för metod 3, för vilken datorberäkningar ska genomföras för bedömning av spänningsnivå alternativt töjningsnivå.

    Som underlag för arbetet har 3 konstruktioner använts. Den nybyggda järnvägstunneln genom Gamla Uppsala, samt två äldre broar/tunnlar i Ulriksdal och Antuna. De gjutförhållanden som rådde och sprickbegränsande åtgärder som användes återskapades i programvaran ConTeSt Pro. Det är en mjukvara som utvecklats speciellt för denna typ av temperatur- och spänningsberäkningar för ung betong. Genom tillhandahållna temperaturmätningar och anteckningar från arbetsplatser har de verkliga förhållandena återskapats för att kunna beräkna rättvisa spänningsnivåer.

    Under den 2-4 november 2016 genomfördes fältarbete i Stockholm och Uppsala. Målet var att få större förståelse för projektet, men främst att kartera tunneln i Gamla Uppsala efter sprickor. Detta krävdes för att kunna jämföra de töjningskvoter som erhölls från beräkningarna med den verkliga uppsprickningen i konstruktionerna.

    En stor del av arbetet var att beräkna töjningskvoterna i ConTeSt. Orsaken till detta var att beräkningen simulerade ett tidsspann som vanligen uppgick till två månader. I och med detta förändrades yttre faktorer som lufttemperatur mycket i modellen, vilket tog lång tid att återskapa. Då alla 19 konstruktioner som beräknats var klara sammanställdes de beräknade töjningskvoterna och jämfördes med de karterade sprickorna samt kraven på spricksäkerhetsfaktorn från den svenska sprickmodellen.

    När resultaten analyserats tydde mycket på att spricksäkerhetsfaktorn var för låg för en av de studerade exponeringsklasserna. Detta beror troligtvis på att toleransen för ändringar i väderlek och fel vid gjutning är för snäv, vilket kan resultera i uppsprickning. Slutligen föreslås en ökning av säkerhetsfaktorn, så att den svenska sprickmodellen motverkar sprickor i ung betong på ett mer effektivt sett.

  • 91.
    Erlingsdotter Stridsman, Rebecca
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Månsson, Felicia
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Residual Stresses Induced by Welding in High Performance Steel2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Today, high performance steel as a construction material is treated as conventional steel in the European standards. Referring to the Eurocodes, the buckling curves for dimensioning of steel constructions only presents values up to steel grade S460, meaning that the full potential of high performance steel is not considered. If the amplitude of the residual stresses in high performance steel can be confirmed to be smaller than in conventional steel, more slender cross sections could be obtained when using high performance steel, HPS. One challenge with the residual stress patterns for HPS is its variation obtained in different studies, where new resulting residual stress patterns are found depending on plate thickness and manufacturing methods for the steel.

     

    Residual stresses in steel are stresses not associated with external forces. The stresses are instead caused by internal forces, such as differencing temperature. Residual stresses can therefore be connected to stresses due to welding. Considering HPS, it is distinctive from conventional steel in the way that it has higher performance in tensile strength, toughness, weldability, corrosion and cold formability.

     

    This study has been performed by Finite Element Modelling in the software Abaqus and by performing an experiment. The objective of this study was to find residual stress patterns and to compare the results with existing residual stress patterns according to the European Convention for Constructional Steel (ECCS) and the Swedish handbook for steel constructions provided by Boverket (BSK 07), but also to compare the results with previous studies.

     

    The influence of temperature changes due to welding was studied for a L-section made of steel S690QL, where only the longitudinal stresses were considered during the research. The numerical analysis in Abaqus was performed using a DFlux subroutine, which is written in Fortran language. Furthermore, the analysis was divided into subparts; one heat transfer analysis and two three-dimensional stress analyses for two different boundary conditions, with the purpose of obtaining results in terms of temperature and stresses for further analysis. The experimental work was performed on three specimens using Gas Metal Arc Welding, where thermocouples and strain gages were used for measuring temperature and strains respectively.

     

    Conclusions of this study were that the resulting residual stress pattern obtained the experiment was similar to the stress pattern for a L-section in BSK 07, while the resulting residual stress pattern obtained in the numerical analysis was mostly comparable to ECCS, but with similarities to BSK 07 and a previous study by Cherenenko & Kennedy (1990).  Moreover, the resulting residual tensile stresses obtained in the study had the same amplitude or lower than what is specified in BSK 07.

  • 92.
    Fahleson, Claes
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Provning av skjuvförbindare2005Rapport (Annet vitenskapelig)
  • 93.
    Fathi, Navid
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Study of an axially loaded sandwich panel: Study based on finite element analysis and experimentation of a 1 mm flat profiled steel plate2017Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Sandwich panels produced by Isolamin AB are comprised of a core, such as polyurethane or mineral wool that is attached between two steel plates. The problem that the thesis attempts to solve is whether a flat profiled sandwich panel of 1mm can withstand loads from 3-storey modular house. To solve this problem investigation in other forms of buckling behaviour will be done. This investigation will be carried out through experimentation, finite element modelling and calculations to find resistance values. Ultimately, these results will be analysed and examined and prove if the sandwich panel with 1mm steel plate is able to withstand a 3-storey modular house. 

  • 94.
    Feneuil, Blandine
    et al.
    Aalto University, Concrete Technology Laboratory, Department of Civil and Structural Engineering, School of Engineering, Aalto University.
    Habermehl-Cwirzen, Karin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Cwirzen, Andrzej
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion. Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Contribution of CNTs/CNFs morphology to reduction of autogenous shrinkage of Portland cement paste2016Inngår i: Frontiers of Structural and Civil Engineering, ISSN 2095-2430, E-ISSN 2095-2449, Vol. 10, nr 2, s. 224-235Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this experimental study, carbon nanotubes (CNTs) and carbon nanofibers (CNFs) were dispersed by intensive sonication in water in the presence of superplasticizer and subsequently mixed with Portland cement with water/ cement ratios varying between 0.3 and 0.4. The autogenous shrinkage in the fresh stage was investigated. The CNTs and CNFs were characterized by high resolution scanning electron microscopy (SEM) and the hydrated pastes were studied by X-ray diffraction and SEM. The results showed a reduction of the autogenous shrinkage by 50% for pastes containing small amounts (0.01 wt%) of nanomaterials. Higher additions appeared to be less effective. The highest reduction of shrinkage was observed for carbon nanofibers which were long, rather straight and had diameters of around 200 nm. The result showed that the addition of nanomaterials accelerated the hydration processes especially in the early stages of hydration. The effect was the most pronounced in the case of functionalized nanotubes. The proposed mechanism resulting in the reduction of the autogenous shrinkage was a combination of nano-reinforcing effects, alterations of hydration and microstructure of the hydrated matrix.

  • 95.
    Feng, Kailun
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriellt och hållbart byggande. Department of Construction Management, Harbin Institute of Technology, Harbin, China.
    Lu, Weizhuo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriellt och hållbart byggande.
    Chen, Shiwei
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. Department of Construction Management, Harbin Institute of Technology, Harbin, China.
    Wang, Yaowu
    Department of Construction Management, Harbin Institute of Technology, Harbin, China.
    An Integrated Environment–Cost–Time Optimisation Method for Construction Contractors Considering Global Warming2018Inngår i: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 10, nr 11, artikkel-id 4207Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Construction contractors play a vital role in reducing the environmental impacts during the construction phase. To mitigate these impacts, contractors need to develop environmentally friendly plans that have optimal equipment, materials and labour configurations. However, construction plans with optimal environment may negatively affect the project cost and duration, resulting in dilemma for contractors on adopting low impacts plans. Moreover, the enumeration method that is usually used needs to assess and compare the performances of a great deal of scenarios, which seems to be time consuming for complicated projects with numerous scenarios. This study therefore developed an integrated method to efficiently provide contractors with plans having optimal environment-cost-time performances. Discrete-event simulation (DES) and particle swarm optimisation algorithms (PSO) are integrated through an iterative loop, which remarkably reduces the efforts on optimal scenarios searching. In the integrated method, the simulation module can model the construction equipment and materials consumption; the assessment module can evaluate multi-objective performances; and the optimisation module fast converges on optimal solutions. A prototype is developed and implemented in a hotel building construction. Results show that the proposed method greatly reduced the times of simulation compared with enumeration method. It provides the contractor with a trade-off solution that can average reduce 26.9% of environmental impact, 19.7% of construction cost, and 10.2% of project duration. The method provides contractors with an efficient and practical decision support tool for environmentally friendly planning.

  • 96.
    Feng, Kailun
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriellt och hållbart byggande. Department of Construction Management, Harbin Institute of Technology, Harbin, 150001, China.
    Lu, Weizhuo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriellt och hållbart byggande.
    Olofsson, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriellt och hållbart byggande.
    Chen, Shiwei
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand. Department of Construction Management, Harbin Institute of Technology, Harbin, 150001, China.
    Yan, Hui
    School of Civil Engineering and Transportation, South China University of Technology, Guangzhou, 510641, China.
    Wang, Yaowu
    Harbin Institute of Technology, Information Technology Institute, Harbin, China.
    A predictive environmental assessment method for construction operations: Application to a Northeast China case study2018Inngår i: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 10, nr 11, artikkel-id 3868Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Construction accounts for a considerable number of environmental impacts, especially in countries with rapid urbanization. A predictive environmental assessment method enables a comparison of alternatives in construction operations to mitigate these environmental impacts. Process-based life cycle assessment (pLCA), which is the most widely applied environmental assessment method, requires lots of detailed process information to evaluate. However, a construction project usually operates in uncertain and dynamic project environments, and capturing such process information represents a critical challenge for pLCA. Discrete event simulation (DES) provides an opportunity to include uncertainty and capture the dynamic environments of construction operations. This study proposes a predictive assessment method that integrates DES and pLCA (DES-pLCA) to evaluate the environmental impact of on-site construction operations and supply chains. The DES feeds pLCA with process information that considers the uncertain and dynamic environments of construction, while pLCA guides the comprehensive procedure of environmental assessment. A DES-pLCA prototype was developed and implemented in a case study of an 18-storey building in Northeast China. The results showed that the biggest impact variations on the global warming potential (GWP), acidification potential (AP), eutrophication (EP), photochemical ozone creation potential (POCP), abiotic depletion potential (ADP), and human toxicity potential (HTP) were 5.1%, 4.1%, 4.1%, 4.7%, 0.3%, and 5.9%, respectively, due to uncertain and dynamic factors. Based on the proposed method, an average impact reduction can be achieved for these six indictors of 2.5%, 21.7%, 8.2%, 4.8%, 32.5%, and 0.9%, respectively. The method also revealed that the material wastage rate of formwork installation was the most crucial managing factor that influences global warming performance. The method can support contractors in the development and management of environmentally friendly construction operations that consider the effects of uncertainty and dynamics.

  • 97.
    Forsberg, Thomas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Pusch, Roland
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Yang, Ting
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Knutsson, Sven
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geoteknologi.
    Borehole seals of expandable clay with desired water content by use of “dry water”2017Inngår i: Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dense clay can be used for sealing of boreholes. Keeping the clay confined in perforated tubes it can be inserted in boreholes of nearly any length and diameter. Expansion of the clay to fill the borehole takes place by uptake of water and migration of clay through the perforation. The clay thereby exerts a swelling pressure on the confining rock causing effective sealing. For shallow boreholes to be sealed a very low initial degree of water saturation of the clay may be valuable since this makes the clay expand and seal the hole quickly, but for certain cases the clay should have a higher degree of water saturation. This can be required for moderating the rate of clay densification that may otherwise give too high wall friction for placement in very long holes. Sealing of very deep holes and holes containing highly radioactive waste makes temperature important: the heat-induced expansion of initially fully saturated clay can fracture the confining rock. The issue is therefore to prepare the clay inserts withproperly selected water content. The paper describes preparation of clay seals by mixing air-dry clay powder with nanoparticles of water droplets coated with very thin shells of a hydrophobic silicious substance (“dry water”). It behaves as dry powder and is easily mixed with dry clay. On compaction to the desired density the shells break into aggregates of minute fragments while water becomes homogeneously distributed in the mass. Laboratory and bench-scale testing verify that the properties of clay prepared in this way are the same as of clay saturated by sorbing water through a filter, a process that can take hundreds of years for big samples. Keywords:borehole sealing, clay blocks, degree of saturation, density, “dry water”, water content1. IntroductionSeveral concepts for sealing of boreholes and disposal of radioactive waste make use of dense

  • 98.
    Ge, Yuanfei
    et al.
    Southeast University, Nanjing.
    Yu, Shaojun
    Southeast University, Nanjing.
    Yu, Zhang
    Southeast University, Nanjing.
    Tu, Yongming
    Southeast University, Nanjing.
    Ohlsson, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    A refined model of concrete carbonation by coupling of multi-factors2016Inngår i: IABSE CONGRESS, STOCKHOLM, 2016: Challenges in Design and Construction of an Innovativeand Sustainable Built Environment / [ed] ennart Elfgren, Johan Jonsson, Mats Karlsson, Lahja Rydberg-Forssbeck and Britt Sigfrid, H - 8093 Zürich, Switzerland, 2016, s. 1198-1206Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Studies on carbonation of concrete play an important role in accurately predicting the service life. However, most research work on carbonation of concrete was carried out in qualitative ways and seldom in quantitative ways. In this paper, based on conservation of mass of C3S(s), C2S(s), CSH(s), CH(s), CH(aq), CO2(aq) and CO2(g) and one-dimensional diffusion and reaction equation, a refined mathematical model of concrete carbonation composed of a series of partial differential equations (PDEs) was built. Corresponding MATLAB codes were developed with calculus of differences to solve the mathematical model of concrete carbonation. The results of the mathematical models in this paper agree very well with measurements, which show that this model can be used to accurately predict concrete carbonation as well as remaining service life of concrete bridges and other concrete structures

  • 99.
    Ghasemi, Yahya
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Flowability and proportioning of cementitious mixtures2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Understanding the role of constituents of cementitious mixtures as the most globally used human-made material and their effect on the flowability of the blends is of great importance. A comprehensive understanding of the ingredients of mixtures allows for optimized proportioning of constituents and can lead to a reduction in cement and water demand of the blends.

    The thesis focuses on relating the flow of mixtures to the specific surface area of the particles through the concepts of excess water layer theory by assuming that the particles are enveloped by a thin film layer that separates the grains and lubricates their surfaces. However, in order to study the film thickness, it is inevitable to consider packing density and specific surface area of the particles. Both of the mentioned parameters and their influence on water requirement of mixtures were investigated as a part of the project.

    The theoretical part of the thesis includes background and explanation of the concepts and theories used in conducting the research including particle packing theory, specific surface area, and excess layer theories. In addition, the thesis attempts at defining and formulating terms and parameters such as representative shape, mixer efficiency, and optimal packing.

    The experimental part of the thesis consists of laboratory measurements of packing density in the loose state, estimation of specific surface area using microtomography and slump tests for mortar and concrete.

    The results of the thesis indicate that the available packing models can estimate the packing density with acceptable accuracy. In addition, it was shown that it is possible to estimate flowability of mixtures based on information about the specific surface area of the constituents. A mix design approach is introduced which predicts flow spread of slump test, a measure that is often used in laboratories and at the building sites.

    Moreover, the research revealed that the estimation of the specific surface area of particles can be improved by assuming a platonic solid shape for the particles instead of spheres. Furthermore, the mixer efficiency was quantified and optimization of mixtures against packing density and water requirement was explained.

    The finding of the project lays a foundation for a simple workability based mix design approach.

  • 100.
    Ghasemi, Yahya
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Emborg, Mats
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    A method for obtaining optimum packing of aggregates for concrete at the onset of flow2017Inngår i: Proceedings of the 23rd Nordic Concrete Research Symposium, Oslo, Norway: Nordic Concrete Federation , 2017, s. 361-365Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Particle packing models have been studied extensively during past decades and led to development of some complex and relatively accurate predictions of packing of granular materials. While the models are capable of calculating the packing density for different volumetric share of constitutes, the concept of optimum packing remains unclear. The study aims to define optimum packing based on particle packing theory and excess water layer theory .The approach makes it also possible to calculate amount of paste that is required to put a concrete mixture at the onset of flow. Some pilot tests conducted in the laboratory showed good agreement with calculated data.

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