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Publikationer (10 of 63) Visa alla publikationer
Nilsson, M., Nilimaa, J., Emborg, M., Hösthagen, A. & Westerholm, M. (2024). Materialdata för beräkning av temperatur, hållfasthet och spänningar – betong med AnlFA-cement, flygaska och slagg. Luleå: Luleå tekniska universitet
Öppna denna publikation i ny flik eller fönster >>Materialdata för beräkning av temperatur, hållfasthet och spänningar – betong med AnlFA-cement, flygaska och slagg
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2024 (Svenska)Rapport (Övrigt vetenskapligt)
Ort, förlag, år, upplaga, sidor
Luleå: Luleå tekniska universitet, 2024. s. 38
Serie
Teknisk rapport / Luleå tekniska universitet, ISSN 1402-1536
Nationell ämneskategori
Infrastrukturteknik Annan materialteknik
Forskningsämne
Byggkonstruktion
Identifikatorer
urn:nbn:se:ltu:diva-106153 (URN)978-91-8048-597-5 (ISBN)
Projekt
Trafikverkets och Anläggning AMAs metoder för undvikande av tidig sprickbildning i betong – nyutveckling med hänsyn till miljökriterier
Tillgänglig från: 2024-06-10 Skapad: 2024-06-10 Senast uppdaterad: 2024-06-10Bibliografiskt granskad
Al-Gburi, M., Gonzalez-Libreros, J., Sas, G. & Nilsson, M. (2022). Quantifying the Environmental Impact of Railway Bridges Using Life Cycle Assessment: A Case Study. In: IABSE Symposium Prague 2022: Challenges for Existing and Oncoming Structures - Report: . Paper presented at IABSE Symposium Prague 2022: Challenges for Existing and Oncoming Structures, Prague, Czech Republic, May 25-27, 2022. International Association for Bridge and Structural Engineering
Öppna denna publikation i ny flik eller fönster >>Quantifying the Environmental Impact of Railway Bridges Using Life Cycle Assessment: A Case Study
2022 (Engelska)Ingår i: IABSE Symposium Prague 2022: Challenges for Existing and Oncoming Structures - Report, International Association for Bridge and Structural Engineering, 2022Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

As emission regulations in the EU are becoming stricter, the reduction of greenhouse gas emissions from the construction industry has become a pressing need. As part of the efforts related to this issue, it has been found that Environmental Life Cycle Analysis (LCA) approaches are required to optimize the design, construction, operation, and maintenance of buildings and infrastructure assets. In this paper, The Institution of Structural Engineers guidance on how to calculate the embodied carbon in structures is used as LCA model and evaluated in a case study. The guidance divides the structure´s life cycle into five stages (A1-A3: Product, A4-A5: Construction process, B1-B7: Use, C1-C4: End of live and D: Benefits and loads beyond the system boundary) and the environmental impact is measured in terms of carbon dioxide equivalent emissions (kgCo2e) or global warming potential (GWP). The model was applied to an existing reinforced concrete trough bridge, which is a structure type commonly used in Swedish railways. Results show that that the model was effective and simple for investigating the environmental impact of the studied structure. 

Ort, förlag, år, upplaga, sidor
International Association for Bridge and Structural Engineering, 2022
Nyckelord
Life cycle analysis, Reinforced concrete, Railway Bridge, Embodied carbon, Global warming potentia
Nationell ämneskategori
Annan samhällsbyggnadsteknik
Forskningsämne
Byggkonstruktion
Identifikatorer
urn:nbn:se:ltu:diva-91104 (URN)2-s2.0-85133522166 (Scopus ID)
Konferens
IABSE Symposium Prague 2022: Challenges for Existing and Oncoming Structures, Prague, Czech Republic, May 25-27, 2022
Tillgänglig från: 2022-06-09 Skapad: 2022-06-09 Senast uppdaterad: 2023-09-05Bibliografiskt granskad
Al-Gburi, M., Jonasson, J.-E. & Nilsson, M. (2022). Reducing Thermal Crack Risks Caused by Restraint in Young Concrete - A Case Study on Walls of Water Tanks. Nordic Concrete Research, 66(1), 41-54
Öppna denna publikation i ny flik eller fönster >>Reducing Thermal Crack Risks Caused by Restraint in Young Concrete - A Case Study on Walls of Water Tanks
2022 (Engelska)Ingår i: Nordic Concrete Research, ISSN 0800-6377, Vol. 66, nr 1, s. 41-54Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Concrete cracks in structures such as water tanks and nuclear power stations cause anxiety to owners, contractors and engineers. These cracks may significantly increase the structure’s permeability and thus increase leakage, reduce durability, and eventually lead to loss of structural functionality. Therefore it is important to minimize their occurrence and size. To identify effective ways of minimizing cracking in young concrete segments, a parametric study was conducted using the finite element method (FEM). Parameters considered include casting sequence, joint position, wall height, and cooling. The study examined continuous and jumped casting approaches to the casting of a cylindrical reinforced concrete tank for a sewage-treatment plant, with and without the application of the ‘kicker’ technique in which the lower part of the wall is cast with the slab. The main cause of cracking is thermal change and restraint imposed by adjacent older structures, and the FEM predictions agree well with experimental observations. Continuous casting is most effective at minimizing cracking because it creates only two contact edges between newly cast and existing structures producing the lowest level of restraint. The kicker technique is shown to be very effective for reducing restraint and consider rephasing.

Ort, förlag, år, upplaga, sidor
Walter de Gruyter, 2022
Nationell ämneskategori
Bearbetnings-, yt- och fogningsteknik Byggproduktion
Forskningsämne
Byggkonstruktion
Identifikatorer
urn:nbn:se:ltu:diva-92219 (URN)10.2478/ncr-2022-0001 (DOI)000825200600004 ()
Anmärkning

Validerad;2022;Nivå 2;2022-07-21 (sofila)

Tillgänglig från: 2022-07-22 Skapad: 2022-07-22 Senast uppdaterad: 2023-09-05Bibliografiskt granskad
Nilforoush, R., Pia, G., Nilsson, M. & Elfgren, L. (2020). Anchorage capacity and performance in plain and steelfibre-reinforced-concrete. In: Jan Bien; Jan Biliszczuk; Pawel Hawryszkow; Maciej Hildebrand; Marta Knawa-Hawryszkow; Krzysztof Sadowski (Ed.), 1st IABSE Online Symposium 2020: Synergy of Culture and Civil Engineering - History and Challenges. Paper presented at 1st IABSE Online Symposium, Wroclaw, Poland (Online), October 7-9, 2020 (pp. 700-709). International Association for Bridge and Structural Engineering (IABSE)
Öppna denna publikation i ny flik eller fönster >>Anchorage capacity and performance in plain and steelfibre-reinforced-concrete
2020 (Engelska)Ingår i: 1st IABSE Online Symposium 2020: Synergy of Culture and Civil Engineering - History and Challenges / [ed] Jan Bien; Jan Biliszczuk; Pawel Hawryszkow; Maciej Hildebrand; Marta Knawa-Hawryszkow; Krzysztof Sadowski, International Association for Bridge and Structural Engineering (IABSE) , 2020, s. 700-709Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

Nowadays, prefabricated concrete components made from Steel-Fiber-Reinforced Concrete (SFRC) are widely used in the construction industry. These components are often connected to existing or new structural elements through various fastening systems. Previous studies have shown that the addition of steel fibers to concrete mixture substantially improves the fracture properties of concrete. To date, however, rather limited research is available on the behavior of fastening systems in SFRC. To improve the current knowledge of fastening systems to SFRC structures, a pilot experimental study is carried out on cast-in-place anchor bolts embedded in Plain Concrete (PC) and SFRC members. In this study, the influence of the presence of steel fibers and concrete compressive strength on the anchorage capacity and performance is evaluated. Furthermore, the applicability of current design methods is evaluated for anchorage systems in SFRC.

Ort, förlag, år, upplaga, sidor
International Association for Bridge and Structural Engineering (IABSE), 2020
Nyckelord
Anchor bolt, Design recommendations, Fiber-reinforced concrete, Headed anchor, Plain concrete, Pull-out test
Nationell ämneskategori
Annan samhällsbyggnadsteknik
Forskningsämne
Byggkonstruktion
Identifikatorer
urn:nbn:se:ltu:diva-85852 (URN)2-s2.0-85103462408 (Scopus ID)
Konferens
1st IABSE Online Symposium, Wroclaw, Poland (Online), October 7-9, 2020
Forskningsfinansiär
Svenska Byggbranschens Utvecklingsfond (SBUF)
Anmärkning

ISBN för värdpublikation: 978-385748169-7

Tillgänglig från: 2021-06-22 Skapad: 2021-06-22 Senast uppdaterad: 2023-09-05Bibliografiskt granskad
Nilforoush, R., Nilimaa, J., Bagge, N., Puurula, A., Ohlsson, U., Nilsson, M., . . . Elfgren, L. (2020). Fracture energy of concrete for bridge assessment. In: Jan Bien; Jan Biliszczuk; Pawel Hawryszkow; Maciej Hildebrand; Marta Knawa-Hawryszkow; Krzysztof Sadowski (Ed.), 1st IABSE Online Symposium 2020: Synergy of Culture and Civil Engineering - History and Challenges. Paper presented at 1st IABSE Online Symposium 2020, Wroclaw, Poland (Online), October 7-9, 2020 (pp. 692-699). International Association for Bridge and Structural Engineering (IABSE)
Öppna denna publikation i ny flik eller fönster >>Fracture energy of concrete for bridge assessment
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2020 (Engelska)Ingår i: 1st IABSE Online Symposium 2020: Synergy of Culture and Civil Engineering - History and Challenges / [ed] Jan Bien; Jan Biliszczuk; Pawel Hawryszkow; Maciej Hildebrand; Marta Knawa-Hawryszkow; Krzysztof Sadowski, International Association for Bridge and Structural Engineering (IABSE) , 2020, s. 692-699Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

In numerical assessments of concrete bridges, the value of the concrete fracture energy GF plays an important role. However, mostly the fracture energy is only estimated based on the concrete compressive strength using empirical formulae. In order to study methods to determine the concrete fracture energy for existing bridges, tests were carried out on 55-year-old concrete from a bridge tested to failure in Kiruna in northern Sweden. Uniaxial tensile tests are performed on notched cylindrical concrete cores drilled out from this and other bridges. In the paper, different methods to determine the concrete fracture energy are discussed and recommendations are given for assessment procedures.

Ort, förlag, år, upplaga, sidor
International Association for Bridge and Structural Engineering (IABSE), 2020
Nyckelord
Assessment of structures, Brittleness, Concrete modelling, Fracture energy, Three-point-bending test, Uniaxial tensile test
Nationell ämneskategori
Infrastrukturteknik
Forskningsämne
Byggkonstruktion
Identifikatorer
urn:nbn:se:ltu:diva-85850 (URN)2-s2.0-85103462867 (Scopus ID)
Konferens
1st IABSE Online Symposium 2020, Wroclaw, Poland (Online), October 7-9, 2020
Forskningsfinansiär
TrafikverketLuleå tekniska universitet
Anmärkning

ISBN för värdpublikation: 978-385748169-7

Tillgänglig från: 2021-06-22 Skapad: 2021-06-22 Senast uppdaterad: 2023-09-05Bibliografiskt granskad
Cyron, W., Nilsson, M., Emborg, M. & Ohlsson, U. (2019). Bonded Concrete Overlays: A Brief Discussion on Restrained Shrinkage Deformations and Their Prediction Models. Nordic Concrete Research, 61(2), 107-129
Öppna denna publikation i ny flik eller fönster >>Bonded Concrete Overlays: A Brief Discussion on Restrained Shrinkage Deformations and Their Prediction Models
2019 (Engelska)Ingår i: Nordic Concrete Research, ISSN 0800-6377, Vol. 61, nr 2, s. 107-129Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Bonded concrete overlays (BCO) on bridge decks are beneficial solutions due to their superior properties as compared to the typical asphalt pavement. A significant number of overlays suffer however, from occurrence of cracks and delamination due to poor bond, and restrained shrinkage and thermal dilation. Over the past years different appraisals for estimation of the restrained deformations have been developed, from micro-scale models, based on poromechanics, to empirical equations as given in B3 or B4 models suggested by Baiant. This paper provides a short overview of calculation models along with a brief theoretical explanation of shrinkage mechanism.

Ort, förlag, år, upplaga, sidor
Walter de Gruyter, 2019
Nyckelord
bridge, overlay, concrete, shrinkage, creep
Nationell ämneskategori
Infrastrukturteknik
Forskningsämne
Byggmaterial; Byggkonstruktion
Identifikatorer
urn:nbn:se:ltu:diva-95682 (URN)10.2478/ncr-2019-0019 (DOI)000508428100007 ()
Anmärkning

Godkänd;2023;Nivå 0;2023-02-23 (hanlid)

Tillgänglig från: 2023-02-23 Skapad: 2023-02-23 Senast uppdaterad: 2023-09-05Bibliografiskt granskad
Sabourova, N., Grip, N., Tu, Y., Wang, C., Enochsson, O., Blanksvärd, T., . . . Elfgren, L. (2019). Railway Concrete Arch Bridge over Kalix River at Långforsen: Dynamic Properties and Load-Carrying Capacity. Luleå: Luleå University of Technology
Öppna denna publikation i ny flik eller fönster >>Railway Concrete Arch Bridge over Kalix River at Långforsen: Dynamic Properties and Load-Carrying Capacity
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2019 (Engelska)Rapport (Refereegranskat)
Abstract [en]

The concrete arch bridge over Kalix River at Långforsen was built in 1960 and has a mid-span of 89,5 m and a height of 13,7 m. The bridge owner, Trafikverket, wanted to increase its allowable axle load from 225 to 300 kN. Field tests were carried out under service condition and with ambient vibrations. The test results were used to update and validate Finite Element Models. At last, the refined models were used to check the possibility to increase the axle load.

According to earlier assessments, most parts of the bridge is capable of carrying an axle load of 330 kN. The only critical sections are located in the beams carrying the rail on top of the arch in the section where the beams are united with the arch. Here the stresses in the longitudinal bottom reinforcement are slightly too high.

These sections have been studied in a FEM model for different loads and results show maximum strains of about 50·10-6 corresponding to stresses of only about 10 MPa in the reinforcement in the critical sections. Live load vertical deflections of the crown of the arch is of the order of only ± 6 mm. Dynamic studies have also been made showing that fatigue is no issue. Altogether the studies show that the bridge is able to carry an increased axle load of 300 kN without problems.

Ort, förlag, år, upplaga, sidor
Luleå: Luleå University of Technology, 2019. s. 44
Serie
Forskningsrapport / Luleå tekniska universitet, ISSN 1402-1528
Nyckelord
Concrete Arch Bridge, Railway, Dynamic Properties, Load-Carrying Capacity
Nationell ämneskategori
Infrastrukturteknik
Forskningsämne
Byggkonstruktion
Identifikatorer
urn:nbn:se:ltu:diva-76116 (URN)978-91-7790-473-1 (ISBN)
Forskningsfinansiär
Trafikverket
Tillgänglig från: 2019-09-25 Skapad: 2019-09-25 Senast uppdaterad: 2023-09-05Bibliografiskt granskad
Nilforoush, R., Nilsson, M. & Elfgren, L. (2018). Experimental Evaluation of Influence of Member Thickness, Anchor-Head Size, and Orthogonal Surface Reinforcement on the Tensile Capacity of Headed Anchors in Uncracked Concrete. Journal of Structural Engineering, 144(4), Article ID 04018012.
Öppna denna publikation i ny flik eller fönster >>Experimental Evaluation of Influence of Member Thickness, Anchor-Head Size, and Orthogonal Surface Reinforcement on the Tensile Capacity of Headed Anchors in Uncracked Concrete
2018 (Engelska)Ingår i: Journal of Structural Engineering, ISSN 0733-9445, E-ISSN 1943-541X, Vol. 144, nr 4, artikel-id 04018012Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Cast-in-place headed anchors with different head sizes embedded in plain and reinforced concrete members of various thicknesses were subjected to pullout tests. The influence of member thickness, size of the anchor head, and orthogonal surface reinforcement on the tensile capacity and performance of anchor bolts was evaluated. The member thickness varied from 1.5 to 3.0 times the anchor embedment depth and headed anchors with small, medium, and large heads were tested.

The experimental results of the present study showed that increasing member thickness and/or the use of orthogonal surface reinforcement lead to increased anchorage capacity and anchorage ductility, whereas the anchorage stiffness decreases slightly. In contrast to the anchorage ductility, the tensile breakout resistance and the anchorage stiffness increase significantly with increasing size of the anchor head.

The experimental results corresponded closely to numerical results from a previous study (Nilforoush et al. 2016 a & b), which suggested a modified model incorporating several modification factors for improving the predictive capability of the Concrete Capacity (CC) method. In the present study, these factors yielded improved prediction of the tensile breakout capacity of the tested headed anchors.

Ort, förlag, år, upplaga, sidor
American Society of Civil Engineers (ASCE), 2018
Nyckelord
headed anchor, anchor bolt, concrete cone breakout, concrete splitting, member thickness, anchor head, surface reinforcement
Nationell ämneskategori
Samhällsbyggnadsteknik Infrastrukturteknik
Forskningsämne
Konstruktionsteknik
Identifikatorer
urn:nbn:se:ltu:diva-66332 (URN)10.1061/(ASCE)ST.1943-541X.0001976 (DOI)000425620500004 ()2-s2.0-85040823012 (Scopus ID)
Anmärkning

Validerad;2018;Nivå 2;2018-01-23 (andbra)

Tillgänglig från: 2017-10-31 Skapad: 2017-10-31 Senast uppdaterad: 2023-09-05Bibliografiskt granskad
Al-Gburi, M., Jonasson, J.-E. & Nilsson, M. (2018). Prediction of Restraint in Second Cast Sections of Concrete Culverts using Artificial Neural Networks (ed.). European Journal of Environmental and Civil Engineering, 22(2), 226-245
Öppna denna publikation i ny flik eller fönster >>Prediction of Restraint in Second Cast Sections of Concrete Culverts using Artificial Neural Networks
2018 (Engelska)Ingår i: European Journal of Environmental and Civil Engineering, ISSN 1964-8189, E-ISSN 2116-7214, Vol. 22, nr 2, s. 226-245Artikel i tidskrift (Refereegranskat) Published
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

Ort, förlag, år, upplaga, sidor
Taylor & Francis, 2018
Nationell ämneskategori
Infrastrukturteknik
Forskningsämne
Konstruktionsteknik
Identifikatorer
urn:nbn:se:ltu:diva-13947 (URN)10.1080/19648189.2016.1186116 (DOI)000427321300006 ()2-s2.0-84969262827 (Scopus ID)d43d84f0-c1d2-4a54-9629-77677abf0d2c (Lokalt ID)d43d84f0-c1d2-4a54-9629-77677abf0d2c (Arkivnummer)d43d84f0-c1d2-4a54-9629-77677abf0d2c (OAI)
Anmärkning

Validerad;2017;Nivå 2;2017-12-04 (svasva)

Tillgänglig från: 2016-09-29 Skapad: 2016-09-29 Senast uppdaterad: 2023-09-05Bibliografiskt granskad
Nilforoush, R., Nilsson, M. & Elfgren, L. (2017). Experimental evaluation of tensile behaviour of single cast-in-place anchor bolts in plain and steel fibre-reinforced normal- and high-strength concrete. Engineering structures, 147, 195-206
Öppna denna publikation i ny flik eller fönster >>Experimental evaluation of tensile behaviour of single cast-in-place anchor bolts in plain and steel fibre-reinforced normal- and high-strength concrete
2017 (Engelska)Ingår i: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 147, s. 195-206Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Cast-in-place anchor bolts embedded in plain and steel fibre-reinforced normal- and high-strength concrete members were subjected to monotonic tensile loads. The influence of the concrete member thickness, concrete strength, and the addition of steel fibres to the concrete mixture, on the anchorage capacity and performance was evaluated. The experimental results were evaluated in terms of anchorage capacity, anchorage ductility and stiffness as well as failure mode and geometry. Furthermore, the validity of Concrete Capacity (CC) method for predicting the tensile breakout capacity of anchor bolts in plain and steel fibre-reinforced normal- and high-strength concrete members was evaluated.

The anchorage capacity and ductility increased slightly with increasing member thickness, whereas the anchorage stiffness decreased slightly. In contrast to the anchorage ductility, the anchorage capacity and stiffness increased considerably with increasing concrete compressive strength. The anchorage capacity and ductility also increased significantly with the addition of steel fibres to the concrete mixtures. This enhanced capacity and ductility resulted from the improved flexural tensile strength and post-peak cracking behavior of steel fibre-reinforced concrete.

The average ratio of measured strengths to those predicted by the CC method for anchors in plain concrete members was increased from 1.0 to 1.17 with increasing member thickness. In steel fibre-reinforced concrete, this ratio varied from 1.29 to 1.51, depending on the member thickness and the concrete strength.

Ort, förlag, år, upplaga, sidor
Elsevier, 2017
Nyckelord
Anchor bolt, Headed anchor, Concrete cone breakout, Splitting failure, Normal-strength concrete, High-strength concrete, Member thickness, Steel fibre-reinforced concrete
Nationell ämneskategori
Samhällsbyggnadsteknik Infrastrukturteknik
Forskningsämne
Konstruktionsteknik
Identifikatorer
urn:nbn:se:ltu:diva-63862 (URN)10.1016/j.engstruct.2017.05.062 (DOI)000408073500015 ()2-s2.0-85020246241 (Scopus ID)
Anmärkning

Validerad;2017;Nivå 2;2017-06-12 (andbra)

Tillgänglig från: 2017-06-10 Skapad: 2017-06-10 Senast uppdaterad: 2023-09-05Bibliografiskt granskad
Organisationer
Identifikatorer
ORCID-id: ORCID iD iconorcid.org/0000-0002-3459-2855

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