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  • 101.
    Bernander, Stig
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Svensk, Ingmar
    Luleå tekniska universitet.
    On the brittleness of soft clays1982Rapport (Annet vitenskapelig)
  • 102. Bernspång, Lars
    Iterative and adaptive solution techniques in computational plasticity1991Doktoravhandling, med artikler (Annet vitenskapelig)
  • 103. Bernspång, Lars
    et al.
    Hammam, T.
    Mattiasson, K.
    Schedin, E.
    Melander, A.
    Samuelsson, A.
    Verification of an explicit finite-element code for the simulation of the press forming of rectangular boxes of coated sheet steels1993Inngår i: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 39, nr 3-4, s. 431-453Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The industrial aim for shorter lead times in the development process for new products has encouraged a fast development of finite-element procedures for the simulation of sheet-metal forming. These procedures can shorten the design stage for new sheet-forming tools and the try-out period. In order to reach these goals robust calculation procedures and extensive verification of results are required. This paper presents a detailed validation of one promising type of finite-element code, namely the explicit code DYNA3D. Experiments for verification were performed on a zinc-coated sheet steel with a hot-dip galvanized coating. Stretch forming and deep drawing of cylindrical cups were performed. Rectangular boxes were formed from rectangular blanks and blanks with cut corners. Dies both with and without draw beads were used. Punch forces, flange draw-in and strain distributions were measured. The pressings with cylindrical shape were used to determine coefficients of friction with a fitting procedure based on comparison of data from pressings and from the DYNA3D calculations. These tribological data and constitutive data of the steels were used in the simulation of pressings of rectangular boxes. The calculations with DYNA3D gave a good description of flange draw-in and the strain distributions in the pressings. In most of the cases studied the punch-force curves were well reproduced. It is concluded that the present code is well suited for the simulation of sheet-forming operations.

  • 104. Bernspång, Lars
    et al.
    Mattiasson, Kjell
    Chalmers University of Technology.
    Samuelsson, Alf
    Chalmers University of Technology.
    A quasi-dynamic approach to the analysis of sheet metal forming1991Rapport (Annet vitenskapelig)
  • 105. Bernspång, Lars
    et al.
    Mattiasson, Kjell
    Chalmers University of Technology.
    Samuelsson, Alf
    Chalmers University of Technology.
    Sheet metal forming modelled as a quasi-dynamic process1991Rapport (Annet vitenskapelig)
  • 106. Bernspång, Lars
    et al.
    Samuelsson, A.
    Chalmers University of Technology.
    Kussner, M.
    Technische Hochschule Darmstadt.
    Wriggers, P.
    Technische Hochschule Darmstadt.
    The consistent strain method in finite element plasticity1995Inngår i: Computers & structures, ISSN 0045-7949, E-ISSN 1879-2243, Vol. 54, nr 1, s. 27-33Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An algorithm for finite element analysis of problems in elastoplasticity with continuous stress and strain approximation is presented. By a global iteration procedure, equilibrium is preserved at the nodes in a weak sense, and the local constitutive relation between stresses and strains is satisfied. A high order numerical integration is used to achieve a good quality stiffness matrix and to evaluate the boundary between elastic and plastic regions in the case of partly plastic elements.

  • 107.
    Bien, Jan
    et al.
    Wroclaw University of Technology.
    Elfgren, LennartLuleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.Olofsson, JanSkanska.
    Sustainable bridges: assessment for future traffic demands and longer lives2007Collection/Antologi (Annet vitenskapelig)
  • 108.
    Bien, Jan
    et al.
    Wroclaw University of Technology, WUT, Poland.
    Jakubowski, K
    Wroclaw University of Technology, WUT, Poland.
    Kaminski, Tomasz
    WUT, Wroclaw, Poland.
    Rawa, Pawel
    WUT, Wroclaw, Poland.
    Helmerich, Rosemarie
    BAM, Bundesanstalt für Materialprüfung, Berlin, Germany.
    Niederleithinger, Ernst
    Federal Institute for Materials Research and Testing, BAM, Berlin, Germany.
    Reiss, M
    UMinho, Guimaraes, Portugal.
    Kubiak, Z
    PLK, Polish Railways, Poland.
    Demonstration bridge C: Masonry Arch Structure: Sustainable Bridges Background document 7.42007Rapport (Fagfellevurdert)
    Abstract [en]

    The bridge was selected as a typical masonry arch bridge for demonstration and testing of the project achievements. The age (built 1875), construction and span length (arch radius 4,97 m) of the structure are representative for masonry bridges in Europe. The bridge also doesn't have any technical documentation as most of old masonry bridges. From the practical point of view it is interesting that the track in service is placed asymmetrically, just on one side of the bridge.

    Within the works performed on the bridge the following activities can be distinguished:

    • NDT testing of the structure geometry and material in situ,

    • Laboratory test of specimens taken form the structure,

    • Numerical analyses for evaluation of the bridge load capacity and the ultimate load.

  • 109.
    Bien, Jan
    et al.
    Wroclaw University of Technology, WUT, Poland.
    Kmita, Jan
    Wroclaw University of Technology, WUT, Poland.
    Krzyzanowski, Józef
    Wroclaw University of Technology, WUT, Poland.
    Rawa, Pawel
    WUT, Wroclaw, Poland.
    Prototype of exciter for vibration tests and concept of monitoring system: Sustainable Bridges Background document 5.62007Rapport (Fagfellevurdert)
    Abstract [en]

    This report is a description of the main principles of the proposed monitoring system, testing procedures, techniques of data acquisition and processing. After general information on dynamic tests in the bridge monitoring the prototype of exciter is described. The main principles and assumptions according to its construction are presented. Tests of the exciter executed in laboratory conditions as well as in field are presented and discussed.  General principles of the monitoring system based on vibration tests carried out by means of the built exciter are described. Practical application of the monitoring system based on vibration tests is described for example of a damage test carried out on a Demonstration Bridge  located in Siechnice close to Wrocław.

  • 110.
    Bien, Jan
    et al.
    Wroclaw University of Technology, Poland.
    Rawa, Pawel
    Wroclaw University of Technology, Poland.
    Kaminski, Tomas
    Wroclaw University of Technology, Poland.
    Possibilities of unification of bridge condition evaluation: Sustainable Bridges SB-D3.32007Rapport (Fagfellevurdert)
    Abstract [en]

    This report is presenting possibilities as well as some conceptions of European harmonization in the area of bridge condition assessment. The proposals are addressed to all railway authorities to stimulate discussion on potential needs and possible directions of the unification process. Solutions developed by the Project can be recommended for implementation in the next versions of the existing bridge management systems or in the anew created systems. The proposed concepts can be also applied as independent external computer-based tools of bridge condition assessment supporting the existing bridge management systems.

    The main objectives of the presented report can be listed as follows:

    • presentation of proposed basic terminology in the field of bridge condition assessment;

    • presentation and comparison of bridge geometry models which can be applied in computer systems supporting assessment of bridge condition;

    • presentation of proposal of hierarchical classification of bridge damages as a first step to harmonization of the procedure of bridge condition assessment;

    • presentation of proposal of quantitative measures for all basic types of bridge damages for improvement of precision and objectivity of condition assessment;

    • presentation of conception of bridge condition evaluation based on numerical quantificationof damages and supported by the computer expert tools.

  • 111.
    Bischoff, Reinhard
    et al.
    EMPA, Swiss Federal Laboratory for Materials, Testing and Research.
    Meyer, Jonas
    EMPA, Zurich.
    Enochsson, Ola
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Feltrin, Glauco
    EMPA, Zurich.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Event-based strain monitoring on a railway bridge with a wireless sensor network2009Inngår i: Structural Health Monitoring of Intelligent Infrastructure: Proceedings of the 4th International Conference on Structural Health Monitoring of Intellgent Infrastructure / [ed] Urs Meier; Bernadette Havranek; Masoud Motavalli, Zürich: EMPA-Akademie , 2009, s. 74-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a monitoring application with a wireless sensor network that was performed on a 95 years old riveted steel railway bridge. In order to perform an accurate assessment, strains were monitored on critical elements to catch the real loading during the passage of heavy freight trains. The wireless sensor network deployed on the bridge consisted of 8 nodes supplied with resistance strain gages and the root node connected to a solar energy rechargeable, battery powered base station. The monitoring system was operated in event-based mode to achieve an energy efficient operation to prolong the lifetime of the sensor network. The event detection was carried out with ultra low power MEMS acceleration sensors, which measured continuously the accelerations of the bridge and detected an approaching train. If this occurred, the sensor generated an interrupt that immediately switched on the strain gage's conditioning board and starts the measurement. Switching on the conditioning board shortly before starting the measurement, however, produces biased raw data because the strain gage was still heating up due to the current flow. Instead of eliminating the time-dependent bias by adding a dummy gage to the Wheatstone bridge, the bias was removed by post-processing the raw data. The paper demonstrates that this procedure provides sufficiently accurate input data for use in cycle counting based fatigue assessment of steel bridges.

  • 112.
    Björnfot, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Bildsten, Louise
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Erikshammar, Jarkko
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Haller, Martin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Simonsson, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Lessons learned from successful value stream mapping (VSM)2011Inngår i: Proceedings of IGLC-19: 19th Conference of the International Group for Lean Construction / [ed] John Rooke; Dave Bhargav, Lima: Fondo Ed. Pontificia Universidad Católica del Peru , 2011, s. 163-173Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    To improve, it’s crucial to see! Vital characteristics of Lean are visualisation and transparency, i.e. allowing everyone to see all what occurs in production. A common tool for this purpose is Value Stream Mapping (VSM). Due to varying flows, performing a successful VSM in construction confers additional challenges. In this paper, lessons learned from successful VSM studies in construction are provided.Three VSM case studies were performed at different companies ranging from patio door manufacturing to kitchen cabinet assembly. Lessons learned can be structured into three phases; preparing the VSM (selecting “value stream leaders” and VSM team, clarifying values, etc.), performing the VSM (use of mapping tools, approximation of key indicators, waste identification, etc.), and following-up the VSM (Plan-Do-Check-Act, evaluating customer values, etc.).For the involved companies, the lessons learned imply the start of a “Lean journey” even though the involved companies found it difficult to relate VSM improvements to business strategies. Consequently, there are opportunities to further improve the application of VSM. However, it’s important to remember that VSM is about the straight-forward visualisation of flows and that these flows are made transparent for the whole organisation.

  • 113.
    Björnfot, Anders
    et al.
    Faculty of Technology, Economy and Management, Gjøvik University College.
    Johnsson, Helena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Simonsson, Peter
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    'Find-think-write-publish': Lean thinking in scientific paper writing2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Construction research supports long-term development of the construction industry and the society. Thus it is important to evaluate research against existing knowledge and to constantly develop new knowledge. The main mechanism for doing so is publishing scientific papers. In Sweden, praxis has developed that a Ph.D. consists of a handful of scientific papers. The average time period for a Ph.D. is five years after which the funding situation changes drastically. Previously, the duration of Ph.D. studies at Luleå University of Technology, Sweden often exceeded the planned five years, disrupting the flow of Ph.D. examinations. To increase awareness and interest in paper writing, a method was sought to visualise and manage the writing process. This paper investigates how an Oobeya room can be implemented in construction research to support paper writing. Experiences of working with the Oobeya room in three separate research divisions prove that it is possible and fruitful to better manage knowledge in academic institutions. Even though research is creative, it can be properly managed without hampering scientific freedom. Evidence from managing scientific paper writing using the Oobeya room shows that proper management of research will actually create better research that is more publishable with shorter lead times!.

  • 114.
    Blandine, Feneuil
    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.
    Cwircen, Andrzej
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Erratum to: Contribution of CNTs/CNFs morphology to reduction of autogenous shrinkage of Portland cement paste2017Inngår i: Frontiers of Structural and Civil Engineering, ISSN 2095-2430, E-ISSN 2095-2449, Vol. 11, nr 2, s. 255-255Artikkel i tidsskrift (Fagfellevurdert)
  • 115.
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Förstärkning av betong med mineralbaserade kompositer2007Inngår i: V-byggaren : väg- och vattenbyggaren, ISSN 0283-5363, nr 5, s. 70-75Artikkel i tidsskrift (Annet vitenskapelig)
  • 116.
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Mechanical properties of different geometries of CFRP grid: tensile evaluation of material properties2006Rapport (Annet vitenskapelig)
    Abstract [en]

    There are a number of components included in strengthening of concrete with mineral based composites; base concrete that is in need of strengthening, primers, polymer modified cement bonding agents and carbon fibre reinforced polymers (CFRP). CFRP are light weight composites of carbon fibres imbedded in a matrix that can be tailor-made into different geometries. This report is a part of an ongoing evaluation of a concrete strengthening technique using mineral based composites. This report was done to evaluate the tensile properties of different CFRP grids included in strengthening of concrete with mineral based composites. The experimental test set-up was performed as pure tensile of smaller parts of the different grids. The main mechanical properties presented in the report are failure stress, modulus of elasticity and failure strain. The result was compared to the values provided by the manufacturer. In the results no clear trends was evident between the experimental values and the manufacturer values. In the results it can be concluded that the mechanical properties provided by the manufacturer can not be used as design values. The experimental values were both higher and lower than the manufacturer values for the failure stress and modulus of elasticity. Different failure types of the grids are illustrated in the report.

  • 117.
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Mätprogram för broarna över Åby älv och Rautasjokk: FAS 22013Rapport (Annet vitenskapelig)
  • 118.
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Mätprogram för broarna över Åby älv och Rautasjokk: Utmattning och överlast2012Rapport (Annet vitenskapelig)
    Abstract [sv]

    Den här rapporten är beställd av trafikverket som en förstudie om förslag till möjligheterna att mäta på en bro över Åby älv som ligger på stambanan, samt vilka resultat som detta skulle kunna medföra.

  • 119.
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Strengthening of concrete structures by the use of mineral based composites2007Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Strengthening of concrete structures with epoxy bonded carbon fiber reinforced polymers (CFRP) has been proved to be an excellent strengthening technique. However, using epoxy adhesives for bonding do contain some disadvantages such as diffusion closeness, thermal incompatibility to the base concrete, regulations regarding the working environment and minimum application temperature. Some of these drawbacks can be lessened by substituting the epoxy to a polymer reinforced mortar as the bonding agent. A new acronym for strengthening concrete structures with CFRP and polymer reinforced mortars is introduced, mineral based composites (MBC). This thesis presents experimental tests for both flexural strengthening and shear strengthening techniques using CFRP grids and polymer modified mortar as the bonding agent are presented. Flexural strengthening using the MBC system was designed as a pilot study to evaluate suitability of different mortars with different mechanical properties. The outcome of the pilot study on flexural strengthened small scale concrete beams gave indications on the choice of mortar used in the MBC system. A total amount of 21 concrete beams with and without shear strengthening subjected to four-point bending is evaluated in the thesis. The concrete beams were 4.5 m long and had a rectangular cross section of 180 x 500 mm. A number of parameters were varied for these beam specimens namely; concrete strength, shear reinforcement design, mortar properties, grid design and the addition of flexural strengthening using Near Surface Mounted Reinforcement (NSMR). Considering the steel shear reinforcement, three different variations were utilized; no shear reinforcement, a stirrup distance of 250 mm and 350 mm respectively. The results from the experimental study of the shear capacity using MBC on beams with no shear reinforcement indicates that strengthening concrete structures with the MBC system has competitive properties compared to epoxy bonded strengthening techniques. The MBC system reached 97% of the ultimate load achieved by a strengthening system with vertically applied epoxy bonded carbon fibre sheets. The ultimate failure load was increased with the increase of carbon fibre amount in the grid. Using a grid with small distance between the CFRP tows generated a higher first visible shear crack load. A simplified analytical design proposal to estimate the shear resistance contribution of the MBC strengthening system is proposed in the thesis. Reasonable results were obtained compared to experimental ultimate failure loads. Strains were monitored in the longitudinal steel reinforcement and the steel stirrups for the beams with internal steel shear reinforcement. Here it as clear that the use of the MBC strengthening system reduces the strains in the steel stirrups. Further, photmetric strain measurement on the surface of the strengthening system was also assessed. The use of the MBC strengthening system also reduces the prinicpal strain at the surface of the shear strengthening system. It can be concluded that the MBC strengthening system has great potentials to strengthen concrete structures. Further research are however needed in both development of the materials included

  • 120.
    Blanksvärd, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Strengthening of concrete structures by the use of mineral based composites: system and design models for flexure and shear2009Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    A great number of society's resources are invested in existing concrete structures, such as bridges, tunnels, different kind of buildings etc. All of these structures have both an expected function and an expected life span. However, both the function and the life span can be influenced by external factors, e.g. degradation and altered load situations. Further influencing aspects could be mistakes in design or during the construction phase. Repairing and/or strengthening these structures could maintain or increase the function as well as the life span.To strengthen concrete structures by using adhesively bonded fibres or fibre reinforced polymers (FRP) has been shown to be an excellent way of improving the load bearing capacity. The most common adhesive used for this type of strengthening is epoxies. Unfortunately, there are some drawbacks with the use of epoxy adhesives such as diffusion tightness, poor thermal compatibility with concrete and requirements for a safe working environment which might lead to allergic reactions if proper protective clothing is not used. A further limiting factor is the requirement on the surrounding temperature at application. A commonly recommended minimum temperature at the time for application is 10°C, which makes the preparations regarding application during colder seasons much more complicated. However, some of these drawbacks could be reduced by substituting the epoxy adhesive for a mineral-based bonding agent with similar material properties as concrete.The strengthening system and also the topic of this thesis is termed "mineral-based composites" (MBC). The MBC consists in this context of grids of carbon FRP with high tensile strength that are bonded to an existing concrete surface by the use of a cement based bonding agent.The scientific approach in this thesis includes analytical methods to describe load bearing capacity for the strengthened concrete structure in both flexure and shear. The analytical approaches are then verified against experimental results. Above the theoretical and experimental performance of the MBC system a review of state of the art research has been made in order to collate and map existing mineral-based strengthening systems other than the MBC system.To develop and verify the theoretical models and to compare the performance of the MBC system to other possible designs of mineral-based strengthening systems, six papers are appended in the thesis. - The first paper describes the performance of the MBC system when used in flexural strengthening. The experimental program in this paper consists of a concrete slab strengthened with both the MBC system and epoxy based system. In addition, a parametric study was made on small scale beam specimens to evaluate the performance of using different cement-based bonding agents.- The second paper describes the performance of the MBC system when used as shear strengthening. This study consists of experimental results of 23 reinforced concrete beams with different concrete qualities, internal shear reinforcement ratios together with different variations of the CFRP grid design and mineralbased bonding agents. In addition, a comparison is also made to traditional epoxy-based strengthening. This paper also has an analytical approach to estimate the shear resistance.- The third paper describes existing mineral-based strengthening systems and how these perform in comparison to the proposed MBC strengthening system in shear and flexure.- The fourth paper maps different possibilities to design and combine various materials in order to obtain a mineral-based strengthening system. This paper also consists of experimental research on the tensile behaviour of the MBC system when using high performance fibre reinforced cementitious bonding agents (engineered cementitious composites - ECC). In addition, these results and discussions are also coupled to the observations made in flexural and shear strengthening.- The fifth paper gives suggestions on how to estimate the shear bearing capacity of MBC strengthened concrete beams. The suggested shear design approaches are mainly based on traditional shear design models based on truss analogy, but one design presented is based on the compression field theory.- The sixth and last paper describes the strain development in a shear strengthened concrete beam both with and without the MBC system. All of the results from the investigations made in this thesis indicate that the MBC system contributes to increasing the load bearing capacity for strengthened concrete structures considerably. It is also shown that the MBC system can give competitive strengthening effects compared to existing epoxy bonded strengthening systems. From the experimental investigations on the shear strengthened beams it is shown that the strains in the shear span are lowered compared to a non strengthened specimen. This reduction of strains is also shown in the transition zone between the development of macro cracks from micro cracks. The suggested analytical approach in order to estimate the load bearing capacity of strengthened concrete structures in both flexure and shear indicates that realistic estimations can be made. The flexural design is straightforward while the shear design is more intricate. It is however concluded that a simple and safe design could be made based on the "additional" approach using a 45° truss.

  • 121. Blanksvärd, Thomas
    et al.
    Carolin, Anders
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Rosell, E.
    Swedish Road Administration, Borlänge.
    Mineral based bonding of CFRP to strengthen concrete structures2006Inngår i: Bridge maintenance, safety, management, life-cycle performance and cost: proceedings of the Third International Conference on Bridge Maintenance, Safety and Management, Porto, Portugal, 16 - 19 July 2006 / [ed] Paulo J. S. Cruz; Dan M. Frangopol, London: Taylor & Francis Group, 2006, s. 1057-1058Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Strengthening of concrete structures with epoxy bonded carbon fiber reinforced polymers (CFRP) has been proved to be a good strengthening technique. However, this strengthening technique with epoxy adhesives do contain some disadvantages such as diffusion closeness, thermal incompatibility to the base concrete, working environment and minimum application temperature. Some of these drawbacks can be overcome by substituting the epoxy to a polymer reinforced mortar as the bonding agent. This work presents a pilot study with CFRP strengthened concrete beams. In this case the epoxy bonded CFRP has been replaced with a mineral based composite (MBC). The results from the pilot study indicates that the MBC strengthening system do achieve very good composite action and strengthening effects. These results warrant for further research and improvement of the MBC strengthening system

  • 122. Blanksvärd, Thomas
    et al.
    Carolin, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Rosell, Ebbe
    Mineral based bonding to strengthen concrete structures2006Inngår i: Advances in bridge maintenance, safety, management and life-cycle performance: Proceedings of the Third International Conference on Bridge Maintenance, Safety and Management, IABMAS 06, London: Taylor and Francis Group , 2006Konferansepaper (Fagfellevurdert)
  • 123.
    Blanksvärd, Thomas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Häggström, Jens
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Nilimaa, Jonny
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Sabourova, Natalia
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Grip, Niklas
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Carolin, Anders
    Paulsson, Björn
    UIC, Trafikverket.
    Tu, Yongming
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Test to failure of a steel truss bridge: Calibration of assessment methods2014Inngår i: Bridge Maintenance, Safety, Management and Life Extension: proceedings of the Seventh International Conference of Bridge Maintenance, Safety and Management, 7-11 July 2014, Shanghai, China / [ed] Airong Chen; Dan M. Frangopol; Xin Ruan, London: CRC Press, Taylor & Francis Group , 2014, s. 1076-1081Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The steel truss railway bridge at Åby River was built in 1957 with a span of 32 m (105 feet). In 2012 it was replaced by a new steel beam bridge and the old bridge was placed beside the river. It was tested to failure to study its remaining load-carrying capacity in September 2013. The test was carried out by Luleå University of Technology by commission from Trafikverket as a part of the European Research Project MAINLINE (www.mainline-project.eu). In this paper some preliminary results are given. Two hydraulic jacks, anchored by cables to the bedrock, pulled the bridge downwards. The bridge remained elastic up to about three times the original design load and the load could then be almost doubled with substantial yielding deformations before a buckling failure appeared in the top girders for a load of ca. 11 MN (1000 short tons) for a midpoint deflection of ca. 0, 2 m (8 inches). No brittle or fatigue failure in any of the joints appeared and the bridge proved to behave in a ductile way with a substantial hidden capacity.

  • 124.
    Blanksvärd, Thomas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Sas, Gabriel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Strengthening Concrete Structures using Mineral Based Composites2013Inngår i: Proceedings of the 11th International Symposium on Fiber Reinforced Polymer for Reinforced Concrete Structures / [ed] Joaquim Barros; José Sena-Cruz, Universidade do Minho , 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    During the last two decades, strengthening concrete structures with epoxy bonded carbon fiber reinforced polymers (CFRP) has shown excellent results in increasing bearing capacity. However, there are some limitations with epoxy coated concrete surfaces, e.g.; low permeability which may provoke freeze/thaw problems, poor thermal compatibility to the concrete substrate which makes epoxy coating more sensitive to the surrounding temperature and regulations when it comes to the security and health (allergic reactions) of applicators and third party users. In this respect, using mineral based composites (MBC) may overcome some of these challenges associated with epoxy bonded strengthening systems. MBC, in this context, refers to high strength fibers bonded to the surface using a mineral based bonding agent. This study examines the cracking behavior and strain development of shear MBC strengthened RC beams. The results show that using MBC as shear strengthening postpones the formation of macro-cracks and that a considerable strengthening effect is achieved by using MBC.

  • 125. Blanksvärd, Thomas
    et al.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    CFRP and mineral based bonding agents to strengthen concrete structures2008Inngår i: Proceedings, Nordic Concrete Research, Bålsta, Sweden: [ ... XXth Symposium on Nordic Concrete Research & Development ... The current proceedings contain 90 summaries of oral poster presentations] / [ed] Johan Silfwerbrand, Oslo: Norsk Betongforening , 2008, s. 90-91Konferansepaper (Fagfellevurdert)
  • 126. Blanksvärd, Thomas
    et al.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Strengthening of concrete structures with cement based bonded composites2008Inngår i: Nordic Concrete Research, ISSN 0800-6377, nr 2, s. 143-163Artikkel i tidsskrift (Fagfellevurdert)
  • 127.
    Blanksvärd, Thomas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Using mineral based composites for shear strengthening concrete members2012Inngår i: Concrete solutions: proceedings of Concrete solutions, 4th International Conference on Concrete Repair, Dresden, Germany, 26 - 28 September 2011 / [ed] Michael Grantham; Viktor Mechtcherine, Boca Raton, Fla.: CRC Press/Balkema , 2012, s. 623-629Konferansepaper (Fagfellevurdert)
    Abstract [en]

    During the last two decades, strengthening concrete structures with epoxy bonded carbon fiber reinforced polymers (CFRP) has shown excellent results in increasing bearing capacity. However, there are some limitations with epoxy coated concrete surfaces, e.g., low permeability which may provoke freeze/thaw problems, poor thermal compatibility to the concrete substrate which makes epoxy coating more sensitive to the surrounding temperature and regulations when it comes to the security and health (allergic reactions) of applicators and third party users. In this respect, using mineral based composites (MBC) may overcome some of these challenges associated with epoxy bonded strengthening systems. MBC, in this context, refers to high strength fibers bonded to the surface using a mineral based bonding agent. This study examines the cracking behavior and strain development of shear MBC strengthened RC beams. The results show that using MBC as shear strengthening postpones the formation of macro-cracks and that a considerable strengthening effect is achieved by using MBC

  • 128. Blanksvärd, Thomas
    et al.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Carolin, Anders
    Shear crack propagation in MBC strengthened concrete beams2008Inngår i: FRP Composites in Civil Engineering: proceedings of the 4th International Conference on FRP Composites in Civil Engineering ; Zurich, Switzerland, 22 - 24 July 2008 / [ed] Masoud Motavalli, Dübendorf: EMPA-Akademie , 2008Konferansepaper (Fagfellevurdert)
  • 129. Blanksvärd, Thomas
    et al.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Carolin, Anders
    Shear strengthening of concrete structures with the use of mineral-based composites2009Inngår i: Journal of composites for construction, ISSN 1090-0268, E-ISSN 1943-5614, Vol. 13, nr 1, s. 25-34Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rehabilitation and strengthening of concrete structures have become more common during the last 10-15 years, partly due to a large stock of old structures and partly due to concrete deterioration. Also factors such as lack of understanding and the consequences of chloride attack affect the need for rehabilitation. In addition, more traffic and heavier loads lead to the need for upgrading. Existing externally bonded strengthening systems using fiber-reinforced polymers (FRP) and epoxy as bonding agents have been proven to be a good approach to repair and strengthen concrete structures. However, the use of epoxy bonding agents has some disadvantages in the form of incompatibilities with the base concrete. It is, therefore, of interest to substitute epoxy with systems that have better compatibility properties with the base concrete, for example, cementitious bonding agents. This paper presents a study on reinforced concrete beams strengthened in shear with the use of cementitious bonding agents and carbon fiber grids, denoted as mineral-based composites (MBC). In this study it is shown that the MBC system has a strengthening effect corresponding to that of strengthening systems using epoxy bonding agents and carbon fiber sheets. Different designs and material properties of the MBC system have been tested. An extensive monitoring setup has been carried out using traditional strain gauges and photometric strain measurements to obtain strains in steel reinforcement, in FRP, and strain fields on the strengthened surface. It has been shown that the use of MBC reduces strains in the steel stirrups and surface cracks even for low load steps as compared to a nonstrengthened concrete beam.

  • 130.
    Blanksvärd, Thomas
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Täljsten, Björn
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Sas, Gabriel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Mineral based strengthening systems for upgrading RC Structures2012Inngår i: Fib symposium Stockholm 2012: concrete structures for sustainble community : proceedings / [ed] Dirch H. Bager; Johan Silfwerbrand, Stockholm: Swedish Conrete Association , 2012, s. 363-366Konferansepaper (Fagfellevurdert)
    Abstract [en]

    During the last two decades, strengthening concrete structures with epoxy bonded carbon fibre reinforced polymers (CFRP) have shown excellent results in increasing bearing capacity. However, there are some limitations with epoxy coated concrete surfaces, e.g.; low permeability which may provoke freeze/thaw problems, poor thermal compatibility to the concrete substrate which makes epoxy coating more sensitive to the surrounding temperature and regulations when it comes to the safety and health (allergic reactions) of applicators and third party users. In this respect, using mineral based composites (MBC) may overcome some of these challenges associated with epoxy bonded strengthening systems. MBC, in this context, refers to high strength fibres bonded to the surface using a mineral based bonding agent. This study is examining the cracking behaviour and strain development of shear MBC strengthened RC beams. The results show that using MBC as shear strengthening postpones the formation of macro-cracks and that a considerable strengthening effect is achieved by using MBC.

  • 131.
    Bohling, Daniel
    et al.
    Aalto University, Helsinki, Finland.
    Cwirzen, Andrzej
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Habermehl-Cwirzen, Karin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Bond Strength between Glass Fiber Fabrics and Low Water-to-Binder Ratio Mortar: Experimental Characterization2018Inngår i: Advances in Civil Engineering / Hindawi, ISSN 1687-8086, E-ISSN 1687-8094, Vol. 2018, artikkel-id 8197039Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Full utilization of mechanical properties of glass fiber fabric-reinforced cement composites is very limited due to a low bond strength between fibers and the binder matrix. An experimental setup was developed and evaluated to correlate the mortar penetration depth with several key parameters. The studied parameters included fresh mortar properties, compressive and flexural strengths of mortar, the fabric/mortar bond strength, fabric pullout strength, and a single-lap shear strength. Results showed that an average penetration of mortar did not exceed 100 µm even at a higher water-to-binder ratio. The maximum particle size of the used fillers should be below an average spacing of single glass fibers, which in this case was less than 20 µm to avoid the sieving effect, preventing effective penetration. The pullout strength was strongly affected by the penetration depth, while the single-lap shear strength was also additionally affected by the mechanical properties of the mortar.

  • 132.
    Bonath, Victoria
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Fransson, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Isförhållanden inom Luleå hamnbassäng2013Rapport (Annet vitenskapelig)
    Abstract [sv]

    Issituationen i Luleå hamn vintern 2012/13 var normalsvår vilket innebar en ökad istillväxt motsvarade 150 cm ren is i områden som bröts kontinuerligt. Detta ska jämföras med det obrutna istäckets tjocklek som var ca 60 cm. Isen i rännan bestod av klotformade isblock (10 – 120 cm) omgivna av issörja. Under mars månad var isblockens storlek mätt vid vattenytan i genomsnitt 45 cm och andelen vatten eller finfördelad issörja var ca 30%. Analyser av isborrkärnor visar att isblocken hade en hållfasthet som ökade med antalet brytningar och var i paritet med det ostörda istäcket i början av mars. Blocken bestod då till 70% av finkrossad is eller frusen snösörja.Isproduktionen i området med bruten is tycks vara linjärt beroende av antalet negativa graddagar där tillväxttakten uppmättes till 0,235 cm per grad och dygn. En numerisk modell för beräkning av istillväxt föreslås där frysning av issörja vid ytan och under isblock ingår. Modellen stämmer bra överens med uppmätta värden från en ränna nära hamnen som bröts kontinuerligt två gånger i veckan. Mer fältstudier av isbildning och uppbrytning är önskvärd för att öka modellens tillförlitlighet under förhållanden som skiljer sig väsentligt från de som rådde i testrännan. Samtliga mätprotokoll från ismätningarna i rännan finns bifogade i rapporten.Tillgänglig statistik visar att antalet negativa graddagar efter isläggningen i Luleå hamn vid en svår isvinter är ca 1000. Våra mätningar tyder på att det under en sådan vinter bildas 2,4 m ren is om ett vändområde används kontinuerligt. Beräkningar med den numeriska modellen resulterade i en möjlig istjocklek på 3 m under en svår vinter om medeltemperaturen är 50% kallare än under den aktuella mätperioden 2012. I nuläget klarar hamnisbrytaren Viscaria att operera och vända fartyg i bruten is motsvarande 1,4 m. Om tjockare is bildas är det väsentligt att ett nytt vändområde med ostörd is kan tas i bruk. Under en svår isvinter krävs därför att minst tre åtskilda vändområden är tillgängliga i Luleå hamn.

  • 133.
    Bonath, Victoria
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Kurkinen, Eva-Lotta
    SP Sveriges Tekniska Forskningsinstitut.
    Ohlsson, Ulf
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    A comparison between a commercial energy calculation tool for buildings with calculations using a response model2014Inngår i: NSB 2014 10th Nordic Symposium on Building Physics 15-19 June 2014 Lund, Sweden, Malmö, 2014, s. 863-870, artikkel-id 107Konferansepaper (Fagfellevurdert)
  • 134.
    Bonath, Victoria
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Patil, Aniket
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Fransson, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Sand, Björnar
    Laboratory testing of compressive and tensile strength on level ice and ridged ice from Svalbard region2013Inngår i: Proceedings of the 22nd International Conference on Port and Ocean Engineering under Arctic Conditions, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Compression and tensile strength properties are important input data for constitutive modelling. Still strength properties of ridged ice are not yet sufficiently investigated. During winter 2011 and 2012 field trips were performed to the Svalbard region with the aim to investigate structure and strength of pressure ridges. Core samples from different ridges and the surrounding level ice were taken and transported to the laboratory at Luleå University of Technology. Studies on thin sections of the ice samples under cross-polarized light delivered information about internal structure of the ice. Uniaxial compressive and tensile strength tests were performed with horizontal and vertical loading directions. The experimental procedure is explained in detail. Salinity and porosity were measured for each sample. In this paper the mechanical properties obtained from the testing are documented by consideration of crystal type, ice depth and total porosity.

  • 135.
    Bonath, Victoria
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Petrich, Chris
    Northern Research Institute Narvik.
    Sand, Bjørnar
    Northern Research Institute Narvik.
    Fransson, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Cwirzen, Andrzej
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.
    Morphology, internal structure and formation of ice ridges in the sea around Svalbard2018Inngår i: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 155, s. 263-279Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The results from 3 years of comprehensive field investigations on first-year ice ridges in the Arctic are presented in this paper. The scopes of these investigations were to fill existing knowledge gaps on ice ridges, gain understanding on ridge characteristics and study internal properties of ice. The ability of developing reliable simulations and load predictions for ridge-structure interactions is the final principal purpose, but beyond the scope of this paper. The presented data comprise ridge geometry, ice block dimensions from ridge sails, ice structure in the ridge and values on the ridge porosity and the degree of consolidation. The total ridge thickness conformed to other ridges studied in the same regions. The consolidated layer thickness was on average 2–3 times the level ice thickness. Minimum 33% and in average 90% of the ridge keel area was consolidated. The distribution of ice block sizes and block shapes within a ridge appears to be predictable. A new approach for deriving a possible ridging scenario and ridge age is presented. Different steps of the ridge building process were identified, which are in good agreement with earlier simulated ridging events. After formation of very thin lead ice between two floes deformation occurs through rafting and ridging until closure of the lead. Subsequently the adjacent level ice floe fractures proceeding ridge formation until ridging forces exceed driving forces. A time span of 10 days could be assessed for a possible ridge formation date, estimating the ridge age of the studied ridge located east of Edgeøya at 78° N to be 7 to 8 weeks.

  • 136.
    Breisand, Sigmund
    et al.
    Breisand Konsult.
    Hällmark, Robert
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Tidig samverkan gav bättre samverkansbroar2012Inngår i: Samhällsbyggaren, ISSN 2000-2408, Vol. 3, s. 12-15Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 137. Broms, Carl Erik
    et al.
    Elfgren, Lennart
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Skruvförankringar i maskinfundament1983Inngår i: Byggmästaren, ISSN 0007-7550, Vol. 62, nr 9, s. 25-28Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 138.
    Broms, Carl Erik
    et al.
    Jacobson & Widmark AB.
    Johansson, Håkan E
    Rehnström, Arne
    Anchor bolts in reinforced concrete foundations: short time tests1980Rapport (Annet vitenskapelig)
  • 139.
    Broström, Jeremy
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Nyström, Claes
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Lutningar: Från ritning till verklighet2017Independent thesis Basic level (professional degree), 5 poäng / 7,5 hpOppgave
    Abstract [sv]

    Detta dokument redogör för metoden, resultaten och slutsatserna från enfältundersökning där gång och cykelbanors olika procentuella lutning harundersökts. Detta dokument kan användas som vägledning för att lättare föreställasig hur en procentuell lutning på en väg ser ut i verkligheten. Profilritningar av deinmätta vägarna med tillhörande bilder finns tillgängliga som bilagor. Enprofilritning brukar i de flesta fall inneha olika skalor i vertikal och horisontalledvilket kan ge en felaktig bild om storleken på lutningen ifall personen som granskarritningen inte är medveten om detta. I denna rapport går det att läsa om utfallet avde inmätta vägarna i Luleå med omnejd och skillnaden hur en ritning ser ut därskalan är annorlunda i höjd och plan jämfört med en som inte är det. Lutningarna påde befintliga vägarna har jämförts med Trafikverkets gällande krav och råd för huren väg ska utformas och det fastställs huruvida de har efterföljts eller ej. Efter utfördamätningar och sammanställning av värdena har resultatet jämförts och analyserats.Det framgår tydligt att en lutning som i verkligheten inte ser särskilt brant ut blir iförvrängd skala mer lik en skidbacke än en gångbana.

  • 140.
    Buck, Dietrich
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Hagman, Olle
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Wang, Alice
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Träteknik.
    Gustafsson, Anders
    SP Technical Research Institute of Sweden, SP Sustainable Built Environment, Skellefteå.
    Further Development of Cross-Laminated Timber (CLT): Mechanical Tests on 45° Alternating Layers2016Inngår i: WCTE 2016 : Proceedings, Vienna: Vienna University of Technology, Austria , 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

     

    In this paper, a series of experimental bending and compression tests were performed on cross-laminated timber (CLT) products with ±45° alternating layers, to evaluate their performance against conventional panels of 90° orientation. Engineered wood products, such as CLT with ±45° alternating layers can provide opportunities for greater use in larger and more sustainable timber constructions. A total of 40 panels, manufactured in an industrial CLT production line with either of these two configurations, were tested and compared. Panels were evaluated in bending tests n=20 and the remaining ones in compression tests. Results showed that 35% increased the strength in the four-point bending tests for panels containing ±45° alternating layers compared with the 90° alternating layers. Compression strength was increased by 15%. Stiffness increased by 15% in the four-point bending and 30% in the compression. The results indicate that CLT containing ±45° alternating layers has increased strength and stiffness compared to 90° alternating layers. These findings suggest that further developments in CLT are feasible in advanced building applications.

  • 141.
    Bässler, Ralph
    et al.
    BAM, Berlin, Germany.
    Burkert, Andreas
    BAM, Berlin, Germany.
    Eich, G
    BAM, Berlin, Germany.
    Electrochemical Techniques to Detect Corrosion Stage of Reinforcement in Concrete Structures: Suistainable Bridges.  Background document SB3.92007Rapport (Fagfellevurdert)
    Abstract [en]

    In order to initiate necessary rehabilitation measures at the right moment from the safety aspectas well as the economic point of view non-destructively determined information on the current corrosion behavior of the reinforcing steel have a high importance. For that various electrochemical measurement techniques are available, like measurement of corrosion potential, determination of short-circuit currents on corrosion cells, and external controlled electrochemical investigations. In passive conditions the rebar potentials can fluctuate in a wide range depending on different parameters. In some potential areas a clear classification of active (corroding) or passive conditions is not possible. In such cases measurements by Galvanostatic Pulse Method (GPM) might be supportive. Evaluation of the results enables a much better classification regarding the situation at the reinforcement. However the applicability is being discussed controversially. Basing on differences of own and literature results gathered on park decks and bridges as well as in special laboratory approaches it is necessary to evaluate the limitations on real structures. Right now there is a big skepticism in terms of correct applicability of corrosion rate measurement devices. A very good evaluation of the reinforcement corrosion behavior has been achieved in laboratory. In potential ranges, where a clear assignment to passivity or activity could not be made, GPM-technique allows a better evaluation. It can be stated, that GPM is suitable for evaluation of the corrosion rate on uniformly corroding small specimens. In case of very local corrosion spots and wide passive zones on a test plate, also a good qualitative evaluation of the corrosion stage could be achieved using potential mapping. Here it turned out that relatively small corrosion spots only can be detected by a narrow measurement grid. However an evaluation of corrosion behavior in these conditions by GPM seems to be impossible. The GPM-technique is applicable if corrosion conditions on the object are relatively uniform. Only very local corrosion spots on an almost passive structure limit the usability of the achieved values. The limitation and applicability of the technique on real structures have been evaluated on a bridge without significant corrosion.

  • 142.
    Cairns, John
    et al.
    Heriot Watt University, Edinburgh.
    Pantazopoulou, Voula
    Demokritos University of Thrace, Greece.
    Noghabai, Keivan
    Luleå tekniska universitet.
    Rodriguez, Jesus
    Geocisa Dragados Group, Madrid, Spain.
    Bond of corroded reinforcement2000Inngår i: Bond of reinforcement in concrete: state-of-art report / prep. by Task Group Bond Models (former CEB Task Group 2.5), Lausanne: International Federation for Structural Concrete / Task Group Bond Models , 2000, s. 187-215Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 143.
    Caprolu, Giuseppe
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Experimental testing of anchoring devices for bottom rails in partially anchored timber frame shear walls2011Rapport (Annet vitenskapelig)
    Abstract [en]

    Källsner and Girhammar have presented a new plastic design method of wood-framed shear walls at ultimate limit state. This method allows the designer to calculate the load-carrying capacity of shear walls partially anchored, where the leading stud is not anchored against the uplift.The anchorage system of shear walls is provided from anchor bolts and hold downs. Anchor bolts provide horizontal shear continuity between the bottom rail and the foundation. Hold downs are directly connected from the vertical end stud to the foundation. When hold downs are not provided, the bottom row of nails transmits the vertical forces in the sheathing to the bottom rail (instead of the vertical stud) where the anchor bolts will further transmit the forces into the foundation.Because of the eccentric load transfer, transverse bending is created in the bottom rail and splitting often occurs.Bottom rail experimentally studied with respect to two primary failure modes, splitting along the bottom of the bottom rail due to cross-wise bending and splitting along the edge side of the bottom rail due forces perpendicular to the grain for the sheathing-to-framing connections.The parameters varied are the location of the anchor bolt, the size of the washer and the orientation of the pith.The bottom rail was subjected to loading perpendicular to grain through one-sided sheathing.In this report the different test series are presented. Three series were conducted depending on the location on the anchor bolt. In each series different sets were studied depending on the size of the washer and in each set the pith was placed upwards or downwards.The tests showed three different failure modes. In addition to the failure modes that the testing program was aimed at, splitting along the bottom or side of the bottom rail, the final failure was due to plastic bending and withdrawal of the sheathing-to-framing nails.The results show that the size of the washer and the position of the bolt have a significant influence on the maximum load and the failure modes. It was found that decreasing the distance of the washer to the loaded edge of the bottom rail increases the maximum load.

  • 144.
    Carlswärd, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Shrinkage cracking of steel fibre reinforced self compacting concrete overlays: test methods and theoretical modelling: test methods and theoretical modelling2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Steel fibres are often applied as crack reinforcement in overlays even though methods for the design with respect to crack widths are not yet available. Thus, the intention was for the research to form a basis for future design of overlays with respect to cracks. A main ambition was to give guidance on e.g. type of steel fibre reinforced concrete (SFRC) required to limit crack widths and how to prepare the substrate surface in order to produce a high and even base restraint. Test methods and theoretical analysis has been applied to fulfil the aims. The experimental part consisted of end-restrained shrinkage tests, bond tests and half scale overlay tests. End-restrained shrinkage and half scale overlay tests were conducted in order to evaluate the effect of steel fibres for different restraint situations while the bond tests were intended to give information regarding the appropriateness of different substrate treatments from a bond strength perspective. Test results showed that the situation of restraint has a significant influence on the cracking response. A single crack developed if the overlay was restrained only at the ends for both un-reinforced concrete as well as for SFRC. However, the crack width was found to be reduced due to the addition of steel fibres. In case of a continuous restraint provided by bond to the substrate on the other hand, numerous well distributed, fine cracks were observed. For this situation there was no measurable influence of fibres on the width and distribution of cracks. A conclusion is thus that reinforcement is not required in case of thin overlays (depths of 50 mm have been studied) if a high and even bond strength is obtained. Test results verified that high bond strength can be achieved by pre-moistening the substrate prior to overlaying, in combination with thorough cleaning. However, the substrate should be allowed to dry back prior to overlaying, as a wet surface was shown to be deteriorating for the bond strength. Caution is also recommended if the overlay is cast onto a dry substrate. In case of insufficient bond strength, with an apparent risk for partial debonding, i.e. parts of the overlay debond while other parts are still bonded, reinforcement is however required to limit crack widths. A theoretical method has been proposed for the design of SFRC for such situations and predictions have been verified through comparisons with experimental results.

  • 145. Carlswärd, Jonas
    Steel fibre reinforced concrete toppings exposed to shrinkage and temperature deformations2002Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The work presented in the thesis primarily focuses on problems that are characteristic for thin layers of concrete exposed to imposed loads. More specific, the work aims at investigating, or rather finding ways to evaluate the efficiency of steel fibres as regards the limitation of crack widths in concrete under restrained conditions. To fulfil the ambitions a test method was developed in which concrete toppings were placed on the upper face of a bottom slab that constituted a stiff foundation. The toppings were then exposed to temperature loads that successively resulted in both the formation of vertical cracks in the concrete as well as horizontal cracks along the interface to the substructure. A total number of eight tests divided into two series were then performed using the proposed technique of testing. At each such occasion two toppings were tested simultaneously, one Plain Concrete (PC) and one Steel Fibre Reinforced Concrete (SFRC) specimen. In this way a comparative evaluation of the influence of steel fibres was facilitated. Results showed that end hooked steel fibres, in amounts of 30 to 60 kg/m3, in most cases reduced the maximum widths of appearing cracks substantially although the reinforcement ratios were not sufficient to get completely crack free structures. It is also clear from the experiments that the effect to some extent was influenced by the properties of the interface in the sense that the fibre contribution seemed to increase as the bond quality became poorer. A series of restrained shrinkage tests were also performed primarily for the sake of verification. Within the frames of this study a total of eight half- scale toppings, four with a depth of 6 cm and four with 12 cm depth, were cast on the surface of an old concrete floor. Both plain and steel fibre reinforced concrete specimens were included in the series. Also, for comparison reasons some conventional steel bar reinforced toppings were produced as well. After an initial curing period of three days the specimens were exposed to one-sided drying that successively resulted in the development of visible cracks. From a crack limiting point of view it was concluded that steel fibres were at least as effective as the steel bar mesh, although it was clear that none of the alternatives were adequate for the purpose of achieving crack-free structures. However, the main reason as to why the effect of reinforcement was not as pronounced as anticipated was believed to be that the bond proved to be insufficient. In particular, considering that the ends of the toppings were fastened to the floor by means of expanding bolts this resulted in a too severe load situation. Regarding the influence of the depth it was shown that cracks appeared at a considerably earlier stage for the thin toppings. At the end of the measuring period the cracks were also considerably wider. This was explained as being a result of the considerably faster rate of desiccation experienced for a thin layer. A simple linear elastic Finite Element analysis was also conducted to verify the effect of the sectional depth in addition to the influence of the concrete creep on the development of stresses in the concrete. Results from this study showed that stresses are substantially reduced due to creep effects. It was further shown that the progress of tensile stresses in the concrete is somewhat slower for a thicker section, mainly due to the slower shrinkage strain development.

  • 146. Carlswärd, Jonas
    et al.
    Emborg, Mats
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Avoiding undesirable end results of bonded steel fibre concrete overlays: observations from tests and theoretical calculations2014Inngår i: Nordic Concrete Research, ISSN 0800-6377, Vol. 49, s. 93-112Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to a high degree of damages and undesirable final results of bonded overlays, research has been conducted to develop recommendations on design and execution. Laboratory and half scale tests as well as theoretical analyses have been carried out including e. g. base and end restraint tests on overlays with various reinforcement, concrete qualities, substrate preparing and curing. Also, analytical and numerical calculations have been performed. Results reveal that the bond between overlay and substrate is the most critical parameter for a successful final result. Other key parameters are shrinkage and curing, while fibre and bar reinforcement generally proved to be less significant. Theoretical models work well on this case and will be further developed

  • 147.
    Carlswärd, Jonas
    et al.
    Betongindustri AB.
    Emborg, Mats
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Prediction of stress development and cracking in steel fiber-reinforced self-compacting concrete overlays due to restrained shrinkage2010Inngår i: Fiber-Reinforced Self-Consolidating Concrete: Research and Applications, American Concrete Institute, 2010, s. 31-49Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Shrinkage cracking of self-compacting concrete (SCC) overlays with and without steel fibres has been assessed through laboratory testing and theoretical analysis. Test results verified that steel fibre reinforcement has a crack width limiting effect. However, the contribution in case of fibre contents up to 0.75 vol% was not found to be sufficient to distribute cracks in situations where bond to the substrate was nonexistent. Thus, even higher steel fibre contents (or other types of fibres) are required in order to control cracks. A distributed pattern of fine cracks was however obtained even for unreinforced SCC within bonded areas of the overlays. This implies that steel fibres, or other crack reinforcement, are not required if high bond strength is obtained. An analytical model, proposed to assess the risk of cracking and to predict crack widths in overlays, was found to give reasonable correlation with experimental results

  • 148. Carlswärd, Jonas
    et al.
    Emborg, Mats
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Restrained shrinkage cracking of thin overlays made of steel fibre reinforced self-compacting concrete2005Inngår i: Proceedings: Nordic Concrete Research meeting : Sandefjord, Norway 2005 / [ed] Terje Kanstad; Einar Aassved Hansen, Oslo: Norsk Betongforening , 2005, s. 362-364Konferansepaper (Fagfellevurdert)
  • 149. Carlswärd, Jonas
    et al.
    Emborg, Mats
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Shrinkage cracking of steel fibre reinforced SCC overlays2008Konferansepaper (Annet vitenskapelig)
  • 150. Carlswärd, Jonas
    et al.
    Emborg, Mats
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och -produktion.
    Shrinkage cracking of thin concrete overlays2014Inngår i: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, s. 355-359Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to a high degree of damages and undesirable end results of bonded overlays, research is conducted to develop recommendations on design and execution. Laboratory and full scale tests as well as theoretical analyses have been carried out including e. g. base and end restraint tests on overlays with various reinforcement, concrete qualities, substrate preparing and curing. Moreover, analytical and numerical calculations have been performed. Results reveal that the e. g. bond between overlay and substrate is a critical parameter for a successful end result. Another key parameter is sufficient curing, while reinforcement generally proved to be less significant. Theoretical models works well on this structural situation and will be further developed.

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