Change search
Refine search result
123 1 - 50 of 108
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Al-Gburi, Majid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Effect of casting sequences on the restraint in slab-on-ground2014Conference paper (Refereed)
    Abstract [en]

    One of the widespread issues in concrete structures is cracks occurring at early age. Cracks that appear in the young concrete may cause early start of corrosion of rebars or early penetration of harmful liquids or gases into the concrete body. These situations could result in reduced service life and in significantly increased maintenance cost of structures. Therefore it is important for construction companies to avoid these cracks. Restraint represents one of the main sources of thermal and shrinkage stresses at early age concrete. The casting sequence is affected by the restraint from adjacent structures. The present study discusses the influence of five casting sequences for the typical structure slab-on-ground. The aim is to map restraints for a number of possible casting sequences, and to identify the sequence with the lowest restraint. The study covers both continuous and jumped casting sequences, which include one, two and three contact edges. The result shows that the best casting sequence is the continuous technique with one contact edge

  • 2.
    Al-Gburi, Majid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Effect of the boundary conditions on the crack distribution in early age concrete2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 347-351Article in journal (Refereed)
    Abstract [en]

    Restrained movement in early age concrete may cause cracking. The boundary conditions – restraint – influence the possible crack distribution. This study aims at highlighting the effect of such restraint on the crack distribution. This is done by using the “Cracking Model for Concrete” in ABAQUS/Explicit simulating the non-linear behaviour under and after cracking. In the study the typical case wall-on-slab was in focus using a structure previously been tested in laboratory with both fixed and free bottom slab. The result of the modelling shows fairly good agreement with the cracks observed in the tests.

  • 3.
    Al-Gburi, Majid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. College of engineering, University of Mosul, Iraq.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Prediction of Restraint in Second Cast Sections of Concrete Culverts using Artificial Neural Networks2018In: European Journal of Environmental and Civil Engineering, ISSN 1964-8189, E-ISSN 2116-7214, Vol. 22, no 2, p. 226-245Article in journal (Refereed)
    Abstract [en]

    Estimation of restraint is very important for accurately predicting the risk of early thermal and shrinkage cracking in concrete structures. The stress in young concrete is affected by changes in its dimensions during hydration and the restraint imposed by adjoining structures. In concrete culverts, the restraints from existing structures acting upon the first and second casting sections to be cast are different, causing them to exhibit different early cracking behaviour. This work presents a new method for predicting restraint in complex concrete structures using artificial neural networks (ANNs). Finite element calculations were performed to predict restraint in 108 slabs, 324 walls and 972 roofs from second sections of concrete culverts, and the results obtained were used to train and validate ANN models. The ANN models were then used to study the effects of varying selected parameters (the thickness and width of the roof and slab, the thickness and height of the walls, and the length of the culvert section) on the predicted restraint. Mathematical expressions for predicting restraint values in slabs, walls and roofs were derived based on the ANN models’ output and implemented in an Excel spreadsheet that provides a simple way of predicting restraint in practical applications. Restraint values predicted in this way agree well with the results of finite-element calculations

  • 4.
    Al-Gburi, Majid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Reduction of Early Age Crack Risks in Concrete Walls by Using a New Casting Technique2016In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 26, no 3, p. 216-224Article in journal (Refereed)
    Abstract [en]

    Volumetric changes in early age concrete that are restrained might lead to cracks. The degree of restraint is influenced by the casting sequence and the dimensions of the castings. In the current study a new casting technique is proposed to reduce restraint in the newly cast concrete with a new arrangement of the structural joint to the existing old concrete. The proposed technique is valid for the typical structure wall-on-slab using one structural joint. This casting method means that lower part of the wall is cast together with the slab, and that part is called a kicker. Hereby, the behavior of the structure changes from a typical case wall-on-slab to a typical case wall-on-wall. It has been proven by the beam theory and demonstrated by numerical calculations that there is a clear reduction in the restraint from the slab to the wall using kickers. In the paper different kicker heights are studied with the aim of determining the minimum restraint in the upper part of the wall cast in contact with the kicker. The technique using kickers is compared with common measures used in the field to avoid cracking, such as cooling pipes in the new casting and/or heating cables in the adjoining old concrete. The presented method is both cost and time effective, as it opens the possibility to use larger structural length of each casting sequence.

  • 5.
    Al-Gburi, Majid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Using Artificial Neural Network to Predict the Restraint in Concrete Culvert at Early Age2015In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 25, no 3, p. 258-265Article in journal (Refereed)
    Abstract [en]

    Estimation of restraint is very important for accurate prediction of the risk of concrete cracking at early age. The present study predicts the restraint in 324 walls and 972 roofs for a concrete culvert. A parametric study included the thickness and width of the roofs, thickness and height of the walls, thickness and width of the slab, and length of the structures. Each parameter increased or decreased the restraint in the walls and the roofs. The calculation of the restraint was done elastically by the finite-element method (FE). The results were used by an artificial neural network (ANN) tool, where firstly an influential percentage was investigated as input parameters on the restraint prediction. Equations have been derived by the ANN model to calculate the restraint in the walls and the roofs. It was then used in an Excel sheet to calculate the restraint and compare the result with the result from the finite-element calculations giving high accuracy between the ANN model and the FE calculations

  • 6.
    Al-Gburi, Majid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hösthagen, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Simplified methods for crack risk analyses of early age concrete: Part 1: Development of Equivalent Restraint Method2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 46, no 2, p. 17-38Article in journal (Refereed)
    Abstract [en]

    The present study deals with both the compensation plane method, CPM, and local restraint method, LRM, as alternative methods studying crack risks for early age concrete. It is shown that CPM can be used both for cooling and heating, but basic LRM cannot be applied to heating. This paper presents an improved equivalent restraint method, ERM, which easily can be applied both for usage of heating and cooling for general structures. Restraint curves are given for two different infrastructures, one founded on frictional materials and another on rock. Such curves might be directly applied in design using LRM and ERM.

  • 7.
    Al-Gburi, Majid
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Yousif, Salim T
    Mosul University.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Simplified methods for crack risk analyses of early age concrete: Part 2: Restraint factors for typical case wall-on-slab2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 46, no 2, p. 39-56Article in journal (Refereed)
    Abstract [en]

    Existing restraint curves have been applied to the method of artificial neural networks (ANN) to model restraint in the wall for the typical structure wall-on-slab. It has been proven that ANN is capable of modeling the restraint with good accuracy. The usage of the neural network has been demonstrated to give a clear picture of the relative importance of the input parameters. Further, it is shown that the results from the neural network can be represented by a series of basic weight and response functions. Thus, the results can easily be made available to any engineer without use of complicated software.

  • 8. Bernander, Stig
    et al.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nilsson, Martin
    Inverkan av eftergivlighet hos underlaget på spänningar i nygjutna betongkonstruktioner1997In: Bygg & Teknik, ISSN 0281-658X, no 7, p. 25-27Article in journal (Other (popular science, discussion, etc.))
  • 9.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Grip, Niklas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Investigation of changes in modal characteristics before and after damage of a railway bridge: A case study2015In: The IES Journal Part A: Civil & Structural Engineering, ISSN 1937-3260, E-ISSN 1937-3279, Vol. 8, no 2, p. 131-144Article in journal (Refereed)
    Abstract [en]

    The linear, time-invariant transfer function Txy has been utilized for the construction of FRF, based on the ambient vibration measurements. The results presented here indicated the possibility to identify and localize damages in steel railway bridges from the variations in the modal characteristics of the structure. The comparison between the modal characteristics for the healthy and collapsed bridge confirmed that damage had been existed. The abnormal percentage of change in modal damping, between the healthy and any other condition for a structure, can be regarded as a serious indicator for early stages of damage, while the high percentage of change in modal damping can clearly indicate the existence of damage in that structure. The average ratio of change in the damping ratio from the healthy to the collapsed bridge was about 206 % and this ration could be regarded as an index for the existence of a serious damage in steel bridges, which needs further evaluation in other test cases.

  • 10.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    A comparative study on the identification of building natural frequencies based on parametric models2014In: Proceedings of the 33rd IASTED International Conference on Modelling, Identification and Control: February 17 – 19, 2014, Innsbruck, Austria, 2014Conference paper (Refereed)
    Abstract [en]

    The analysis and design of civil engineering structures is a complex problem, which is based on many assumptions to simplify these operations. This in turn, leads to a difference in the structural behaviour between calculations based models and real structures. Structural identification was proposed by many researchers as a tool to reduce this difference between models and actual structures. Moreover, Parametric models and non-parametric models were used intensively for system identification by many researchers. In this research effort, the system identification concept is utilized to identify the natural frequencies for a steel building’s frames. Different black box linear parametric models such as Transfer Function model (TF), Auto-Regressive model with eXternal input model (ARX), Auto-Regressive Moving Average with eXternal input (ARMAX) model, Output Error model structure (OE), and Box-Jenkins model (BJ) were examined for identifying the first 10th natural frequencies for the building’s frames, based on simulation results. Abaqus 6.12 finite-element software was utilized to perform the time history analysis for the examples and the obtained responses at one point of the roofs (assumed as a sensor) were further processed by the parametric models to obtain the building’s natural frequencies based on the Abaqus time history analysis results (assumed as a measurements). After that, Abaqus 6.12 was utlized again to perform another analysis, which is called frequency analysis to obtain the building’s natural frequencies and mode shapes based on the stiffness and mass (not the measurements) of the buildings. The results showed that the linear parametric models TF, ARX, ARMAX, OE, and BJ are robust to identify the natural frequencies of building and they are recommend for future work.

  • 11.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Comfort Level Identification for Irregular Multi-storey Building Subjected to Vibrations2015In: Automation in Construction, ISSN 0926-5805, E-ISSN 1872-7891, Vol. 50, p. 40-49Article in journal (Refereed)
    Abstract [en]

    In this article, the System Identification approach is being used to identify the vertical frequencies of the top storey in a multi-storey building prefabricated from reinforced concrete in Stockholm. Before building construction, detailed investigation indicated that the building will not be affected by train vibrations from the nearby railway yard. After building completion, disturbing vibrations were observed in the building. Three measurement types namely: ambient vibration test, forced vibration test on the rails, and forced vibration test have been performed in order to specify the probable reasons for these vibrations. Five methods of structural identification approach, specifically: ARX, ARMAX, BJ, OEand State Space Models have been implemented for the identification process in this study usingthe tests' results. All the test types and model structures utilized have identified a concentration inthe floor only, which is close to the frequencies of human body parts. Furthermore, the article concludes that the ARMAX model and the Output Error model have indicated an excellent performance to predict the mathematical models of vibration's propagation in the building, when compared with other models used from the three types of tests. In addition, the results of the aforementioned system identification methods, implemented for this study, have indicated that there are no other reasons for the disturbing vibrations still observed in the building. Furthermore, the results confirmed the correctness of the previous theoretical and experimental results obtained by different specialists, who stated that the values of floor acceleration are within the acceptable limits, and the probable reason for any disturbance is the resonance between the generated low frequencies and the human body parts’ frequencies.

  • 12.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Semi-active structural control strategies2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 31-34Article in journal (Refereed)
    Abstract [en]

    The utilization of structural control systems to alleviate the responses of civil engineering structures, under the effects of dynamics loadings, has become a standard technology, while still there are numerous of current research approaches for advancing the effectiveness of these methodologies. It is important for successful application of smart structure to provide an effective control algorithm to compute the control forces to be applied on the building in order to reduce the external disturbances. The aim of this article is to provide a review of the control strategies to control the performance of semi-active systems utilized in civil engineering structures.

  • 13.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Skanska Sverige AB Technology, Bridge and Civil Engineering.
    A state-of-the-art review of Structural Control Systems2015In: Journal of Vibration and Control, ISSN 1077-5463, E-ISSN 1741-2986, Vol. 21, no 5, p. 919-937Article in journal (Refereed)
    Abstract [en]

    Nowadays the utilization of structural control systems for alleviating the responses of civil engineering structures, under the effects of different kinds of dynamics loadings, has become a standard technology, while still there are numerous of current research approaches for advancing the effectiveness of these methodologies. The aim of this article is to review the state of the art technologies in structural control systems by introducing a general literature review for all the types of vibrations control systems that have been appeared till now. These systems can be classified into four main groups: a) passive, b) semi active, c) active, and d) hybrid based on their operational mechanism. A brief description of each of these main groups and their subgroups, with their corresponding advantages and disadvantages will be also extendedly reported in this review. This article will conclude by providing an overview of some innovative practical implementations of devices, which are able to demonstrate their potentials and future directions of structural control systems in civil engineering.

  • 14.
    Ekerfors, Katarina
    et al.
    Luleå tekniska universitet.
    Jonasson, Jan-Erik
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Behaviour of young high-strength concrete1993In: Utilization of High Strength Concrete : Proceedings: Symposium in Lillehammer, Norway / [ed] Ivar Holand, Oslo: Norsk Betongforening , 1993, p. 691-697Conference paper (Refereed)
  • 15.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bernander, Stig
    Emborg, Mats
    Gabrielsson, Henrik
    Groth, Patrik
    Luleå tekniska universitet.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Nilsson, Martin
    Noghabai, Keivan
    Ronin, Vladimir
    Westman, Gustaf
    Design of high performance concrete structures: a Swedish design handbook1999In: Utilization of high strength/high performance concrete: proceedings : symposium in Sandefjord, Norway 20-24 June 1999 / [ed] Ivar Holand; Erik J. Sellevold, Oslo: Norsk Betongforening , 1999, p. 232-242Conference paper (Refereed)
  • 16. Elfgren, Lennart
    et al.
    Emborg, Mats
    Gabrielsson, Henrik
    Groth, Patrik
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Noghabai, Keivan
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Design of high performance concrete structures in Sweden1998In: International Symposium on High-Performance and Reactive Powder Concretes: organized by Université de Sherbrooke / [ed] Pierre-Claude Aïtcin; Yves Delagrave, Sherbrooke, Que: University of Sherbrooke , 1998, p. 139-156Conference paper (Refereed)
  • 17.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Energetically Modified Cement (EMC) and Ordinary Portland cement (OPC): a comparison2000Report (Other academic)
  • 18.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Ronin, Vladimir
    High performance concrete with energetically modified cement (EMC)2004In: Proceedings International Symposium on Ultra-High Performance Concrete: Kassel, 13-15 Sept, 2004 / [ed] Michael Schmidt; E Fehling; Carsten Geisenhanslüke, Kassel: Kassel University Press GmbH, 2004, p. 93-102Conference paper (Refereed)
    Abstract [en]

    The demands of the modern building industry require development of new types of binder materials with improved properties for high and ultra high strength concretes and with significantly improved durability. They will provide new potential possibilities for the controlling of high performance concrete technology. In the Department of Civil Engineering at Luleå University of Technology a study of energetically modified cement (EMC) indicates that it is possible to obtain much more rapid hardening cement than the original cement used. As an example the strength of EMC-concrete increases about 100 per cent at the age of one day compared with a conventional high strength concrete.A new type of the cement gives possibilities to obtain required workability of the concrete mixtures with low water to binder ratios (w/B < 0.24) and achieve the strength levels up to 200 MPa with binder content not exceeding 550 kg/m3. The modification process used in this study means a special mechanochemical treatment in vibrating milling equipment of the blend containing Ordinary Portland Cement (OPC) and silica fume (SF), which increases the surface energy and the chemical reactivity of the newly obtained binder. This results in an accelerating effect, which maintains at least for nine months. According to ongoing investigations the energetically modified cement appears to give a considerable acceleration effect in the whole range of studied temperature. Concretes produced with EMC cement demonstrated very high durability at very severe testing conditions, including drying, saturation in sodium chloride solution and freezing-thawing. These results are very promising and it might be used in a lot of applications as winter concreting, precast element production, special structural elements, repair of buildings, rehabilitation, topping of concrete, floors, roads, etc.

  • 19.
    Elfgren, Lennart
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Olofsson, Thomas
    Emborg, Mats
    Jonasson, Jan-Erik
    High performance concrete structures: a Swedish research program1996In: Concrete in the service of mankind. 4, Radical concrete technology: proceedings of the international conference held at the University of Dundee, Scotland, UK on 24-26 June 1996 / [ed] Ravindra K. Dhir; Peter C. Hewlett, London: Taylor and Francis Group , 1996, Vol. 4, p. 141-150Conference paper (Refereed)
  • 20.
    Emborg, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Carlswärd, Jonas
    Hedin, Christer
    Jonasson, Jan-Erik
    Program kortar ner väntetid när betonggolv ska glättas2010In: Husbyggaren : bygg, el, VVS, anläggning, ISSN 0018-7968, no 2Article in journal (Other (popular science, discussion, etc.))
  • 21.
    Emborg, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Långtidsstabilitet till följd av frysning och tining av betong och bentonit vid förvaring av låg- och medelaktivt kärnavfall i SFR 12007Report (Other academic)
  • 22.
    Emborg, Mats
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Nilsson, Martin
    Utsi, Sofia
    Simonsson, Peter
    Designing robust SCC for industrial construction with cast in place concrete2005In: Second North American Conference on the Design and Use of Self-Consolidating Concrete [and] Fourth International RILEM Symposium on Self-Compacting Concrete; [October 30 - November 2, 2005];Second North American Conference on the Design and Use of Self-Consolidating Concrete [and] Fourth International RILEM Symposium on Self-Compacting Concrete; [October 30 - November 2, 2005: [proceedings] / [ed] Surendra P. Shah, Hanley Wood, 2005, p. 1251-1257Conference paper (Refereed)
  • 23. Emborg, Mats
    et al.
    Jonasson, Jan-Erik
    Westman, Gustaf
    Luleå tekniska universitet.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Crack risk due to thermal and humidity stresses in high performance concrete (EMC)1996In: Proceedings: Nordic Concrete Research Meeting, Espoo, Finland 1996, Oslo: Norsk Betongforening , 1996, p. 56-57Conference paper (Refereed)
  • 24.
    Fjellström, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Bäckström, Henrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Crack-free concrete: an understanding of creep2011In: Nordic Concrete Research: Proceedings of the XXI Nordic Concrete Symposium, Hämeenlinna, Finland 2011, Oslo: The Nordic Concrete Federation , 2011, p. 477-480Conference paper (Refereed)
    Abstract [en]

    A durable structure of concrete is achieved when no cracking occurs during the young ages of the hardening process. Therefore, it’s of importance to address shrinkage and creep correctly. Drying is the primary source of shrinkage, and the time development in shrinkage is an effect of the balance between drying and creep. Therefore, creep is to be measured on sealed and non-sealed specimens in order to investigate the nature of drying creep. Measurements will be performed for loading ages up to 1 year. These experimental data will be used to create accurate models, including both short and long term effects.

  • 25.
    Fjellström, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Heat loss compensation for semi-adiabatic calorimetric tests2013In: Nordic Concrete Research, ISSN 0800-6377, Vol. 47, no 1, p. 39-60Article in journal (Refereed)
    Abstract [en]

    Heat of hydration has long been of importance since it affects the temperature levels within a concrete structure, and thus, potentially affects its durability. The only source of energy is the reaction between cement and water. This energy warms up the concrete sample and all the ambient materials. Therefore, in order to model these energies, the TSA (traditional semi-adiabat) setup is transformed into an associated sphere. By this, the temperature distribution and the energies within each layer of the TSA can be calculated. The sum of all energies gives the total heat of hydration. A refined model using a correction factor is introduced, which accounts for energies lost to the TSA setup materials. Results show that the effect of this factor cannot be disregarded, especially not for TSAs with low cooling factors.

  • 26.
    Fjellström, Peter
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Model for concrete strength development including strength reduction at elevated temperatures2012In: Nordic Concrete Research, ISSN 0800-6377, Vol. 45, no 1, p. 25-44Article in journal (Refereed)
    Abstract [en]

    When casting concrete structures, one of the most important properties is the concrete strength development. The need of actions on site is different at various stages of hardening, from the fresh concrete to the hardened concrete. The paper defines a model analysing maturity and associated strength growth within three important time periods. The model can be applied separately within each of these periods depending on test data available.It is shown in the paper that the temperature plays an important role on the strength development of concrete structures. The hydration rate increases with increased temperatures, which can be described by maturity functions. If the concrete temperature remains high, strength reduction at later ages usually occurs compared to hardening at lower temperature, which may be denoted strength reduction at elevated temperatures or cross over effects. Both these phenomena have been implemented in the model for strength growth presented in the paper. The functionality of the model is demonstrated by evaluation of laboratory tests for five concrete mixes and two types of cement.

  • 27.
    Groth, Patrik
    et al.
    Luleå tekniska universitet.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Olofsson, Thomas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Brottmekanisk modellering av sprickbildning i ung betong2000In: Bygg & Teknik, ISSN 0281-658X, no 7, p. 27-28Article in journal (Other (popular science, discussion, etc.))
  • 28.
    Hatem, Mohammed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Pusch, Roland
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Rheological properties of low pH cement-palygorskite injection grout2013In: Journal of Advanced Science and Engineering Research, ISSN 2231-8844, Vol. 3, no 3, p. 167-192Article in journal (Refereed)
    Abstract [en]

    The rheological properties of cementitious materials containing fine particles, such as mineral admixture were investigated using a Viso Star-L rheometer with cylindrical spindles. Selected features of the behavior of these materials are evaluated from a rheological perspective through literatures results for the past 30 years. One of the important factors that governs the ability of grout to penetrate fractures, channels and porous material is the rheology. The mineral admixture was clay palygorskite which can be used for early gelation because of its thixotropic properties as well as the powder quartz used as aggregate. The cementitious materials were designed and three recipes (MPG1, MPG2 and MPG3) were examined in this research by changing the mix proportions of the mineral admixture palygorskite and water content. For ensuring the accuracy of rheological measurement for the candidate’s grouts, necessary verification was been evaluated such as, influence of mixing time, stability and “time effect” to the accuracy of viscosity measurement, and yield stress as well as the physical properties at 3, 7 and 28 days. The results showed that grouts recipes with quartzite aggregate of different granulometry, are chemically compatible and fulfill the requirement of containing no organic matter. Candidate’s grouts found to satisfy the stable sedimentation criteria with sedimentation rates less than 5% after 2 hours. Furthermore, it was found that the grout recipe 3 followed by 1 showed lower yield stress and plastic viscosity which are (0.1 Pa and 0.269 Pas) and (0.288 Pa and 0.531 Pas) respectively.

  • 29.
    Hatem, Mohammed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Al-Gburi, Majid
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Pusch, Roland
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Design of concrete mixes by systematic steps and ANN2012In: Journal of Advanced Science and Engineering Research, ISSN 2231-8844, Vol. 2, no 4, p. 232-251Article in journal (Refereed)
    Abstract [en]

    The current research caters for the possibility of arriving at a system for designing concrete mixeseasily using available materials locally by specified wide ranges of pre-requisites of three mainprescribed properties to cover a good variety of practical mixes, which are water, water-cement ratioand total aggregate-cement ratio. Using these three properties, a tri-linear form was constructed bygraphical technique manner based on absolute volume approach. This approach defines as asummation of absolute volume for each of these three materials individually water, cement andaggregate should be equal to the absolute volume of whole concrete mixture based on thesealtogether. A quad-form area which includes a wide range of mixes can be formed from thisrepresentation. This area should achieve all the prescribed properties aforementioned. Artificial neuralnetwork concept used in this study also to build easily and quickly system which can be translatedinto Excel sheet. This system predict proportions of concrete mixture and the compressive strengthusing the results designed by the quad-form area method in addition to the data from literature around500 mixes based on local materials used in Iraq. Six input parameters (water to cement ratio, theslump, % of fine to total aggregate content, maximum aggregate size, fineness modulus of fineaggregate and the compressive strength) were used in this system to get the outputs. In addition, nineinput parameters ((water, cement, sand and gravel contents) and the properties of the mix (Finenessmodulus, W/C ratio, the slump, % of fine to total aggregate and the M.A.S)) were used as basis ofcompressive strength model. The algorithm of this system aimed to reduce the high number of trailmixes error as well as saving the labors, cost and time. Results indicated that the concrete mix designand the compressive strength model can be predicted accurately by using graphical perspective andthe ANN approach.

  • 30.
    Hatem, Mohammed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Pusch, Roland
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Pourbakhtiar, Alireza
    Proportioning of cement-based grout for sealing fractured rock-use of packing models2013In: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 5, no 10, p. 765-774Article in journal (Refereed)
    Abstract [en]

    Fractured, very permeable rock hosting repositories for radioactive waste will require grouting. New grout types of possible use where long-term performance is needed should have a small amount of cement for minimizing the increase in porosity that will follow from the ultimate dissolution and erosion of this component. They have to be low-viscous and gain strength early after injection and packing theory can assist designers in selecting suitable proportions of various grout components. Optimum particle packing means that the porosity is at minimum and that the amount of cement paste needed to fill the voids between aggregate particles is very small. Low porosity and microstructural stability must be guaranteed for long periods of time. Organic additives for reaching high fluidity cannot be used since they can give off colloids that carry released radionuclides and talc can be an alternative superplasticizer. Low-pH cement reacts with talc to give high strength with time while Portland cement gives early but limited strengthening. The clay mineral palygorskite can be used for early gelation because of its thixotropic properties. Once forced into the rock fractures or channels in soil it stiffens and serves as a filter that prevents fine particles to migrate through it be lost. However, its hydrophilic potential is too high to give the grout a high density and high strength. According to the experiments carried out most of the investigated grouts are injectable in fractures with apertures down to 100 μm.

  • 31.
    Hatem, Mohammed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Pusch, Roland
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Performance of Cement-poor Concrete with Different Superplasticizers2014In: International Journal of Research and Reviews in Applied Sciences, ISSN 2076-734X, E-ISSN 2076-7366, Vol. 18, no 2, p. 163-172Article in journal (Refereed)
    Abstract [en]

    Concrete can be used for casting plugs in deep boreholes where fracture zones are intersected. They will be exposed to flowing groundwater and be in contact with very tight seals of smectite clay installed where the surrounding rock is tight. The cast concrete must be able to carry the clay segments placed over it after a few days. Its bearing capacity does not have to be very high after that since the clay soon adheres to the rock and carries itself. The concrete must be poor in cement for minimizing the risk of creation of voids caused by dissolution of the cement and it should have “inert” aggregate of quartz-rich material. Inorganic superplasticizers instead of conventional organic ones should be used for eliminating the risk of degradation and loss by formation of colloids that can carry radionuclides to the biosphere from holes bored in repository rock. The two concrete types discussed in the present study had Portland and Merit 5000 low pH cement as binders and crushed quartzite as aggregate. Talc mineral powder and ordinary organic Glenium 51 were used as superplasticizers for comparing their impact on the physical properties. The matrix of the cement-poor talc concrete gave ductile behaviour during initial hardening. The very dense matrix of either of the concretes would not lead to compression of the system even after complete loss of cement, which will happen over a longer period of time. The overall conclusion was that talc as superplasticizer and conditioner of the concrete can make the concrete sufficiently fluid for constructing seals at depth in boreholes, and react with cement to provide high strength with some delay. pH is much lower in Merit than in Portland concrete, which causes less impact on the clay seals. Portland concrete has five times higher strength than Merit concrete after a week but three times lower strength after 28 days.

  • 32.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Groth, Patrik
    Luleå tekniska universitet.
    Jonasson, Jan-Erik
    Reduction of thermal stresses in structures with air-cooling1995In: Thermal cracking in concrete at early ages: proceedings of the international symposium held by RILEM at the Technical Univ. of Munich ..., Oct. 10-12, 1994 / [ed] Rupert Springenschmid, London: Spon press, 1995, p. 433-440Conference paper (Refereed)
  • 33.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Hur skiljer man mellan krympning och temperatur-rörelse?2000In: Bygg & Teknik, ISSN 0281-658X, no 7, p. 12-15Article in journal (Other (popular science, discussion, etc.))
  • 34.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Measurements of self-desiccation and shrinkage of hardening concrete1997In: Moisture Measurement in Concrete Constructions Exposed to Temperature and Moisture Variations: Nordic mini-seminar of the Nordic Concrete Federation, Espoo, Finland 22.8.1997 / [ed] Heikki Kukko; Hemming Paroll, Espoo: Valtion teknillinen tutkimuskeskus. Tie- ja liikennelaboratorio , 1997, p. 73-101Conference paper (Refereed)
  • 35.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Värme- och mognadsutveckling för PK-cement1999Report (Other academic)
  • 36.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Ronin, Vladimir
    Concrete of the future with energetically modified cement (EMC)1996In: Proceedings: Nordic Concrete Research Meeting, Espoo, Finland 1996, Oslo: Norsk Betongforening , 1996, p. 23-24Conference paper (Refereed)
  • 37.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Ronin, Vladimir
    Jonasson, Jan-Erik
    Elfgren, Lennart
    Grönare betong1999In: Bygg & Teknik, ISSN 0281-658X, Vol. 91, no 7, p. 12-13Article in journal (Other (popular science, discussion, etc.))
  • 38.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    Emborg, Mats
    Jonasson, Jan-Erik
    Bernander, Stig
    Hardening technology for concrete structures1997In: Advanced design of concrete structures: [papers presented at the Symposium on Advanced Design of Concrete Structures, held in Chalmers University of Technology in Göteborg, Sweden on June 12 - 14, 1997] / [ed] Kent Gylltoft, Barcelona: International Center for Numerical Methods in Engineering (CIMNE), 1997, p. 313-318Conference paper (Refereed)
  • 39.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    Emborg, Mats
    Jonasson, Jan-Erik
    Bernander, Stig
    Härdningsstyrning av betongkonstruktioner1996In: Byggforskning : Byggforskningsrådets tidning för en bättre byggd miljö, ISSN 1102-3686, no 3, p. 38-39Article in journal (Other (popular science, discussion, etc.))
  • 40.
    Hedlund, Hans
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Westman, Gustaf
    Luleå tekniska universitet.
    Jonasson, Jan-Erik
    Analysis of early age cracking in HPC structures1999In: Utilization of high strength/high performance concrete : proceedings: symposium in Sandefjord, Norway 20-24 June 1999 / [ed] Ivar Holand; Erik J. Sellevold, Oslo: Norsk Betongforening , 1999, p. 1134-1143Conference paper (Refereed)
  • 41.
    Hösthagen, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Equivalent Restraint Method Correlated to Empirical Measurements2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 505-508Article in journal (Refereed)
    Abstract [en]

    The present study deals with the correlation between numerical models and empirical observations in newly cast concrete specimens. The model used is the equivalent restraint method, ERM, which is established from several local restraint method calculations, LRM. The csating of walls in a tunnel construction is investigated. Correlation between models and empirical measurements is established in three steps.

  • 42.
    Hösthagen, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wallin, Kjell
    Projektengagemang i Stockholm AB.
    Stelmarcik, Marcin
    Thermal crack risk estimations for tunnel: equivalent restraint method correlated to empirical observations2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 49, p. 127-143Article in journal (Refereed)
    Abstract [en]

    The present study deals with the correlation between numerical models and empirical observations in newly cast concrete structures. The model used is the equivalent restraint method, ERM, which is established from several local restraint method calculations, LRM. The casting of walls and roof in a tunnel construction is investigated. Correlation between models and empirical measurements is established in three steps: 1) the restraint situation is analyzed; 2) the calculated temperature developments are compared to empirical temperature measurements to calibrate the models; and 3) calculated strain ratios are compared with observed crack patterns, and in general a good correlation is achieved

  • 43.
    Hösthagen, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. anders.hosthagen@ltu.se.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Emborg, Mats
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nilsson, Martin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Thermal Crack Risk Estimations of Concrete Walls: Temperature and Strain Measurements Correlated to the Equivalent Restraint Method2017In: Proceedings of the 23rd Nordic Concrete Research Symposium, Oslo, Norway: Nordic Concrete Federation , 2017Conference paper (Refereed)
    Abstract [en]

     Self-induced non-elastic deformations in hardening concrete, caused by restrained volume changes due to thermal dilatation and moisture deformations, often leads to cracking. In crack risk analyses, determination of the degree of restraint is vital. One model to estimate the restraint and calculate the thermal crack risk is the Equivalent Restraint Method, ERM. The method has previously been analyzed but needs to be further examined and validated. Recordings of tunnel sections were performed and compared to calculated values by ERM. Satisfying correlation between theoretically estimated and observed temperatures, strains and time of through cracking was achieve which is promising for future implementation and testing of the method.

  • 44.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    A study of time-dependent deformations in modern concrete2009In: Creep, shrinkage and durability of concrete and concrete structures: proceedings of the eight international conference on Creep, Shrinkage and Durability of Concrete and Concrete Structures, Ise-Shima, Japan, 30 September - 2 October 2008 / [ed] Tada-aki Tanabe, Boca Raton: CRC Press, Taylor & Francis Group , 2009, p. 1477-1481Conference paper (Refereed)
    Abstract [en]

    If we consider modem concrete structures subjected to severe environment or severe loading, dense concretes are often used. Hereby, two important features are creep and shrinkage that have paramount importance for serviceability, durability, and long-term reliability of structures. This paper presents new models for the prediction of creep and shrinkage deformations in dense concrete structures. The formulas presented have been applied as modifications on the approach of CEB-FIP Model Code aimed for more open concrete structures. Such a procedure makes the framework well known to designers

  • 45.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Aktivitet: Modellering av temperatur- och fuktberoende sprickrisker i ung betong2009Conference paper (Other (popular science, discussion, etc.))
    Abstract [sv]

    (finns endast på engelska)

  • 46.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Betongens värmeutveckling1991In: Bygg & Teknik, ISSN 0281-658X, no 7, p. 19-21Article in journal (Other (popular science, discussion, etc.))
  • 47.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Data for crack analysis of young concrete with and without fly ash2012Report (Other academic)
  • 48.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Materialdata för betong SKANSKA-K6516P2005Report (Other academic)
    Abstract [sv]

    Denna utredning, som omfattar mätning av materialegenskaper för hårdnande betong och utvärdering av resultaten anpassade för att användas i datorsystemet ConTeSt, är ett uppdrag från SKANSKA till LTU (Luleå tekniska universitet).

  • 49.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Modelling of moisture isotherms including alkali effects2000In: Proceedings of the Workshop on Water in Cement Paste & Concrete Hydration and Pore Structure / [ed] Dirch H. Bager, Oslo: Norsk Betongforening , 2000, p. 28-48Conference paper (Refereed)
  • 50.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Modelling of temperature, moisture and stresses in young concrete1994Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The present study consists of three areas, namely modelling of- (1) temperature, (2) moisture state, and (3) stresses in young concrete. The derivation of models, examination of material data, and development of computer programs have progressed differently in these areas. The first area, modelling of temperatures, is the most comprehensive and complete, since it has been researched more extensively than the other areas. On the other hand, the way of modelling stresses in this study is purely theoretical and has not been tested against empirical data, but gives some guidelines for future applications. Finally, the modelling of moisture state is somewhere in between the other two areas. The results can be applied to different fields of concreting, such as estimation of form stripping times, estimation of necessary measures to be taken in winter concreting, study of drying shrinkage cracking, and study of stresses due to varying temperatures in early age concretes. The aim of this report is not to discuss applications, but to give the background and material data used in the models for calculating the temperature, moisture state, and stresses in young concrete. It is shown that temperature can be modelled to within an accuracy of 1 to 2°C which is acceptable for most applications. However, it is essential to have good knowledge of both material data and environmental conditions. For the study of moisture states, a consistent model for the description of desorption and absorption isotherms has been developed. The treatment of both desorption and absorption isotherms in the same theoretical framework makes it possible to introduce scanning curves between these limit curves for subsequent drying and wetting. The effects of alkali have been modelled as an alkali equilibrium isotherm estimated from the known amounts of sodium and potassium oxides in the cement. The alkali influenced curve can be combined with any description of the isotherms with respect to the physically bound water. The need for considering the effects of alkali for higher humidities has been shown in moisture calculations.

123 1 - 50 of 108
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf