Change search
Link to record
Permanent link

Direct link
Publications (10 of 52) Show all publications
Storni, D., Singh, H., Tangrand, K. & Grip, N. (2024). Research on wavelets and artificial intelligence algorithms for structural health monitoring of concrete bridges. Mathematics in Engineering, Science and Aerospace (MESA), 15(1), 131-150
Open this publication in new window or tab >>Research on wavelets and artificial intelligence algorithms for structural health monitoring of concrete bridges
2024 (English)In: Mathematics in Engineering, Science and Aerospace (MESA), ISSN 2041-3165, E-ISSN 2041-3173, Vol. 15, no 1, p. 131-150Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Cambridge Scientific Publishers Ltd, 2024
National Category
Infrastructure Engineering Mathematical Analysis
Research subject
Applied Mathematics
Identifiers
urn:nbn:se:ltu:diva-104451 (URN)
Projects
Herøy FoU
Note

Validerad;2024;Nivå 1;2024-04-09 (hanlid);

Funder: Nordland Fylkeskommune, Norway; Statens Vegvesen, Norway; NTNU; SINTEF; UiT—The Arctic University of Norway (100397)

Available from: 2024-03-04 Created: 2024-03-04 Last updated: 2024-04-22Bibliographically approved
Singh, H., Grip, N. & Nicklasson, P. J. (2021). A comprehensive study of signal processing techniques of importance for operation modal analysis (OMA) and its application to a high-rise building. Nonlinear Studies, 28(2), 389-412
Open this publication in new window or tab >>A comprehensive study of signal processing techniques of importance for operation modal analysis (OMA) and its application to a high-rise building
2021 (English)In: Nonlinear Studies, ISSN 1359-8678, Vol. 28, no 2, p. 389-412Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Cambridge Scientific Publishers, 2021
National Category
Computational Mathematics
Research subject
Applied Mathematics
Identifiers
urn:nbn:se:ltu:diva-83576 (URN)2-s2.0-85121816304 (Scopus ID)
Note

Validerad;2022;Nivå 1;2022-01-21 (johcin)

Available from: 2021-04-09 Created: 2021-04-09 Last updated: 2022-11-09Bibliographically approved
Sabourova, N., Duvnjak, I., Grip, N., Damjanovic, D., Tu, Y., Popescu, C., . . . Elfgren, L. (2020). Detection of sparse damages in plates. In: Jan Bień, Jan Biliszczuk, Paweł Hawryszków, Maciej Hildebrand, Marta Knawa-Hawryszków, Krzysztof Sadowski (Ed.), IABSE Symposium, Wroclaw 2020: Synergy of Culture and Civil Engineering – History and Challenges. Paper presented at IABSE Symposium “Synergy of Culture and Civil Engineering – History and Challenges”, 7-9 October, 2020, Wrocław, Poland (pp. 1141-1148). Zürich: International Association For Bridge And Structural Engineering (IABSE)
Open this publication in new window or tab >>Detection of sparse damages in plates
Show others...
2020 (English)In: IABSE Symposium, Wroclaw 2020: Synergy of Culture and Civil Engineering – History and Challenges / [ed] Jan Bień, Jan Biliszczuk, Paweł Hawryszków, Maciej Hildebrand, Marta Knawa-Hawryszków, Krzysztof Sadowski, Zürich: International Association For Bridge And Structural Engineering (IABSE) , 2020, p. 1141-1148Conference paper, Published paper (Refereed)
Abstract [en]

Structural damage is often a spatially sparse phenomenon, i.e. it occurs only in a small part of the structure. This property of damage has not been utilized in the field of structural damage identification until quite recently, when the sparsity-based regularization developed in compressed sensing problems found its application in this field. In this paper we consider classical sensitivity-based finite element model updating combined with a regularization technique appropriate for the expected type of sparse damage. The validity of the proposed methods is demonstrated using simulations on a bridge. The pros and cons of these methods are discussed.

Place, publisher, year, edition, pages
Zürich: International Association For Bridge And Structural Engineering (IABSE), 2020
Keywords
Damage Detection, Sparse Damage, FEM Updating, Regularization
National Category
Other Civil Engineering Mathematical Analysis
Research subject
Structural Engineering; Applied Mathematics
Identifiers
urn:nbn:se:ltu:diva-81136 (URN)2-s2.0-85103443479 (Scopus ID)
Conference
IABSE Symposium “Synergy of Culture and Civil Engineering – History and Challenges”, 7-9 October, 2020, Wrocław, Poland
Note

ISBN för värdpublikation: 978-3-85748-169-7

Available from: 2020-10-14 Created: 2020-10-14 Last updated: 2022-12-30Bibliographically approved
Wang, C., Zhang, J., Tu, Y., Sabourova, N., Grip, N., Blanksvärd, T. & Elfgren, L. (2020). Fatigue Assessment of Reinforced Concrete Railway Bridge based on a Coupled Dynamic System. Structure and Infrastructure Engineering
Open this publication in new window or tab >>Fatigue Assessment of Reinforced Concrete Railway Bridge based on a Coupled Dynamic System
Show others...
2020 (English)In: Structure and Infrastructure Engineering, ISSN 1573-2479, E-ISSN 1744-8980Article in journal (Refereed) Published
Abstract [en]

This paper proposes a fatigue damage assessment methodology of a reinforced concrete bridge based on a train bridge coupled dynamic analysis system. This coupling system is composed of a vehicle a ballasted track and a bridge structure to realize a coupled vibration analysis during train passages. This methodology adopts the Palmgren Miner rule to linearly accumulate fatigue damage, and accomplishes fatigue assessment based on recommended SN relationships for reinforced concrete from various criteria. In this paper, the dynamic performances of a bridge structure are analyzed with two different vehicle models, a moving load model (and a moving spring mass damper model). Calculated dynamic stresses areused to evaluate the fatigue damage of critical positions in a reinforced concrete bridge. A case study is carried out of a railway arch bridge with a span of 89 m, Långforsen Bridge. It runs over Kalix River on the railway between Kalix and Morjärv in northern Sweden The fatigue assessment is made by combining the presented methodology with measurements. Furthermore, the effects of train speed and axle load on fatigue damage are investigated. The results indicate that good estimations of the fatigue damage assessment are made for four measured cases based on a train-bridge coupled dynamic analysis. For low speeds and light loads no difference could be seen in the cumulative fatigue damage for the two vehicle models. But high speeds and/or heavy load ssignificantly affect the fatigue damage.

Place, publisher, year, edition, pages
Taylor & Francis, 2020
Keywords
Train Bridge Coupling System, Fatigue Damage, Moving Load Model, Moving Spring Mass Damper Model, Reinforced Concrete Railway Bridge
National Category
Infrastructure Engineering Mathematical Analysis
Research subject
Structural Engineering; Applied Mathematics
Identifiers
urn:nbn:se:ltu:diva-76136 (URN)10.1080/15732479.2019.1671467 (DOI)000488187400001 ()2-s2.0-85074260959 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-04-21 (johcin)

Available from: 2019-09-26 Created: 2019-09-26 Last updated: 2023-02-10Bibliographically approved
Duvnjak, I., Damjanović, D., Sabourova, N., Grip, N., Ohlsson, U., Elfgren, L. & Tu, Y. (2019). Damage Detection in Structures – Examples. In: IABSE Symposium 2019: Towards a Resilent Built Environment - Risk and Asset Management. Paper presented at IABSE Symposium 2019, Towards a Resilient Built Environment - Risk and Asset Management, March 27-29, 2019, Guimarães, Portugal (pp. 471-478). nternational Association for Bridge and Structural Engineering (IABSE)
Open this publication in new window or tab >>Damage Detection in Structures – Examples
Show others...
2019 (English)In: IABSE Symposium 2019: Towards a Resilent Built Environment - Risk and Asset Management, nternational Association for Bridge and Structural Engineering (IABSE) , 2019, p. 471-478Conference paper, Published paper (Refereed)
Abstract [en]

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

Place, publisher, year, edition, pages
nternational Association for Bridge and Structural Engineering (IABSE), 2019
Keywords
mode shape damage detection, finite element model updating, 𝑙1-norm regularization
National Category
Engineering and Technology Mathematics Other Civil Engineering
Research subject
Mathematics; Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-73334 (URN)10.2749/guimaraes.2019.0471 (DOI)2-s2.0-85065261356 (Scopus ID)
Conference
IABSE Symposium 2019, Towards a Resilient Built Environment - Risk and Asset Management, March 27-29, 2019, Guimarães, Portugal
Available from: 2019-03-28 Created: 2019-03-28 Last updated: 2023-02-22Bibliographically approved
Sabourova, N., Grip, N., Ohlsson, U., Elfgren, L., Tu, Y., Duvnjak, I. & Damjanović, D. (2019). Detection of Sparse Damages in Structures. In: IABSE Symposium 2019: Towards a Resilent Built Environment - Risk and Asset Management. Paper presented at IABSE Symposium 2019 'Towards a Resilient Built Environment - Risk and Asset Management', 27-29 March, 2019, Guimarães, Portugal (pp. 515-522). International Association for Bridge and Structural Engineering (IABSE)
Open this publication in new window or tab >>Detection of Sparse Damages in Structures
Show others...
2019 (English)In: IABSE Symposium 2019: Towards a Resilent Built Environment - Risk and Asset Management, International Association for Bridge and Structural Engineering (IABSE) , 2019, p. 515-522Conference paper, Published paper (Refereed)
Abstract [en]

Structural damage is often a spatially sparse phenomenon, i.e. it occurs only in a small part of the structure. This property of damage has not been utilized in the field of structural damage identification until quite recently, when the sparsity-based regularization developed in the compressed sensing found its application in this field.

In this paper we consider classical sensitivity-based finite element model updating combined with a regularization technique appropriate for the expected type of sparse damage. Traditionally (1) 𝑙2-norm regularization was used to solve the ill-posed inverse problems, such as damage identification. However, using (2) already well established 𝑙1-norm regularization or (3) our proposed 𝑙1-norm total variation regularization and (4) general dictionary-based regularization allows us to find damages with special spatial properties quite precisely using much fewer measurement locations than the number of possibly damaged elements of the structure. The validity of the proposed methods is demonstrated using simulations on a Kirchhoff plate model. The pros and cons of these methods are discussed.

Place, publisher, year, edition, pages
International Association for Bridge and Structural Engineering (IABSE), 2019
Series
IABSE Symposium Report ; 114
Keywords
sparse damage, 𝑙2-norm, 𝑙1-norm, total variation, dictionary-based regularization, sensitivity
National Category
Mathematical Analysis Other Civil Engineering
Research subject
Mathematics; Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-73335 (URN)10.2749/guimaraes.2019.0515 (DOI)2-s2.0-85065234822 (Scopus ID)
Conference
IABSE Symposium 2019 'Towards a Resilient Built Environment - Risk and Asset Management', 27-29 March, 2019, Guimarães, Portugal
Note

ISBN för värdpublikation: 978-1-5108-8445-8

Available from: 2019-03-28 Created: 2019-03-28 Last updated: 2023-02-22Bibliographically approved
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
Open this publication in new window or tab >>Railway Concrete Arch Bridge over Kalix River at Långforsen: Dynamic Properties and Load-Carrying Capacity
Show others...
2019 (English)Report (Refereed)
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.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2019. p. 44
Series
Research report / Luleå University of Technology, ISSN 1402-1528
Keywords
Concrete Arch Bridge, Railway, Dynamic Properties, Load-Carrying Capacity
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-76116 (URN)978-91-7790-473-1 (ISBN)
Funder
Swedish Transport Administration
Available from: 2019-09-25 Created: 2019-09-25 Last updated: 2023-09-05Bibliographically approved
Singh, H. & Grip, N. (2019). Recent trends in operation modal analysis techniques and its application on a steel truss bridge. Nonlinear Studies, 26(4), 911-927
Open this publication in new window or tab >>Recent trends in operation modal analysis techniques and its application on a steel truss bridge
2019 (English)In: Nonlinear Studies, ISSN 1359-8678, Vol. 26, no 4, p. 911-927Article, review/survey (Refereed) Published
Abstract [en]

Aging of infrastructure causes many problems with great consequences, essentially economical. Operation modal analysis (OMA) is one of the most crucial techniques used for dynamic analysis of civil engineering structures (e.g. bridges, dams or tunnels). OMA uses various time and frequency domain methods to obtain the modal parameters. The analysis of OMA techniques can be used to detect, locate and quantify the damage in a structure. The major challenge for damage detection using OMA is the analysis of a large amount of noisy data collected from sensors. New signal processing techniques and artificial intelligence can play an important role in future research in the area. In this article, we present and discuss recent developments in OMA techniques and also give a concrete example on a steel truss bridge, where the most popular OMA techniques have been implemented and applied.

Place, publisher, year, edition, pages
Cambridge Scientific Publishers, 2019
National Category
Mathematical Analysis
Research subject
Applied Mathematics
Identifiers
urn:nbn:se:ltu:diva-80356 (URN)
Note

Godkänd;2020;Nivå 0;2020-08-18 (alebob)

Available from: 2020-08-11 Created: 2020-08-11 Last updated: 2022-11-09Bibliographically approved
Grip, N., Sabourova, N. & Tu, Y. (2017). Sensitivity-based model updating for structural damage identification using total variation regularization (ed.). Mechanical systems and signal processing, 84(A), 365-383
Open this publication in new window or tab >>Sensitivity-based model updating for structural damage identification using total variation regularization
2017 (English)In: Mechanical systems and signal processing, ISSN 0888-3270, E-ISSN 1096-1216, Vol. 84, no A, p. 365-383Article in journal (Refereed) Published
Abstract [en]

Sensitivity-based Finite Element Model Updating (FEMU) is one of the widely accepted techniques used for damage identification in structures. FEMU can be formulated as a numerical optimization problem and solved iteratively making automatic updating of the unknown model parameters by minimizing the difference between measured and analytical structural properties. However, in the presence of noise in the measurements, the updating results are usually prone to errors. This is mathematically described as instability of the damage identification as an inverse problem. One way to resolve this problem is by using regularization. In this paper, we compare a well established interpolation-based regularization method against methods based on the minimization of the total variation of the unknown model parameters. These are new regularization methods for structural damage identification. We investigate how using Huber and pseudo Huber functions in the definition of total variation affects important properties of the methods. For instance, for well-localized damages the results show a clear advantage of the total variation based regularization in terms of the identified location and severity of damage compared with the interpolation-based solution.For a practical test of the proposed method we use a reinforced concrete plate. Measurements and analysis were performed first on an undamaged plate, and then repeated after applying four different degrees of damage.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Mathematical Analysis Infrastructure Engineering
Research subject
Mathematics; Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-7622 (URN)10.1016/j.ymssp.2016.07.012 (DOI)000388785700020 ()2-s2.0-84991782200 (Scopus ID)605f69d8-d15c-4b74-947a-926770375ecc (Local ID)605f69d8-d15c-4b74-947a-926770375ecc (Archive number)605f69d8-d15c-4b74-947a-926770375ecc (OAI)
Note

Validerad; 2016; Nivå 2; 2016-08-16 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2023-05-09Bibliographically approved
Grip, N., Sabourova, N., Tu, Y. & Elfgren, L. (2017). Vibrationsanalys för tillståndsbedömning av byggkonstruktioner: Tillämpningsexempel : (Main results and summary in Swedish. Detailed results in English Appendices.). Stockholm
Open this publication in new window or tab >>Vibrationsanalys för tillståndsbedömning av byggkonstruktioner: Tillämpningsexempel : (Main results and summary in Swedish. Detailed results in English Appendices.)
2017 (Swedish)Report (Other academic)
Abstract [sv]

I projektet beskrivs och tillämpasnågra metoder för tillståndsbedömningav olika typer av konstruktioner med och utan skador.Tillståndsbedömningen skermed hjälp av vibrationsanalys.Detektering av skador av olika typ och storlekdiskuteras. Randvillkorens betydelse undersöks för att få överensstämmelse mellan förutspådda och uppmätta egenmoder och egenfrekvenser.Med den programvara som utvecklats är det möjligt att detektera sprickor i enkla betongplattor med hjälp av vibrationsmätningar. För mer avancerade konstruktioner finns en potential att vidareutveckla programvaran.Mätningar och analyser presenterasför femkonstruktioner: (1) En betongplatta –Sprickor har kunnat identifieras utifrån vibrationsmätningar och en successivt uppdaterad finit element modell (FEM).(2) En bågbro av betong över Långforsen i Kalix älv–Okända randvillkor har kunnat bestämmasför t ex undergrundens styvhetmedhjälp avuppmätta vibrationer. Detekteringav specifika skadorhar ännu inte kunnat genomföras.(3) En fackverksbro av stålöver Åby älv–Enviss skadedetektering har kunnat genomföras med vibrationsmätningar. Brons sårbarhet för korrosion och lokala mekaniska skador har studerats.(4) En förspänd betongbrotill gruvan i Kiruna–Modeller av bron har arbetats framför obelastatoch brottbelastat tillståndoch jämförts med uppmätta vibrationer med gott resultat.(5) Ett betonghus med nio våningar i Luleå –En FEM-modell av huseti bruksstadiethar tagits fram och resultat från den har jämförts med uppmätta vibrationer med gott resultat.Metoder och resultatpresenteras översiktligti rapportens huvudtext. Detaljerade beskrivningar gesi appendix.I appendix presenterasäven en programvaramed färdiga moduler för de undersökta konstruktionerna. Programmet kan laddas ner och användasfritt

Abstract [en]

In the project,methods are presented and appliedfor assessment ofdifferent types ofbuilding structures with and without damages.The assessmentis done withhelp ofvibration analysis.Detection of defects of different types and sizes are discussed. The influence of boundary conditions isstudied in order to get agreement between predicted and measured Eigen modes and Eigen frequencies.With the program that has been developed,is it now possible to detect cracks in simple concrete structures with help of measurements of vibrations. For more advanced structures there is a potentialto further develop the program. Measurements and analyses have been made for fivestructures:(1) A concrete slab–Cracks have been detected based on vibrationmeasurementsand a successivelyupdated Finite Element Model (FEM).(2) Aconcrete archbridge at Långforsen in Kalix River-Unknown boundary conditions havebeen possible todetermine with help of vibration measurementsregarding for example foundation properties. Detection of specific damages hasnot yet been possible.(3) A steel truss bridge over Åby River–Some detection of damages hasbeen possible to carry outwith Finite Element Model updatingregarding corrosion and mechanical damages.. (4) A prestressed concrete bridge to the mine in Kiruna-Several models of theundamaged and damagedbridgehave been established and they have been calibrated to measured vibration propertieswith good results.(5) A nine storey concrete building in Luleå–A FEM model has been developedfor the serviceability limit stateand results from it has been compared to measured vibrationswith good results.A general presentation is given ofthe developedmethods and resultsin the main text. Detailed descriptions are provided in Appendices.A program is presented with ready-to-use models for the studied structures. The program may be downloaded and is presented in detail in an Appendix.

Place, publisher, year, edition, pages
Stockholm: , 2017. p. 305
National Category
Infrastructure Engineering Building Technologies Computational Mathematics Mathematical Analysis
Research subject
Mathematics; Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-66140 (URN)
Projects
SBUF (Svenska Byggbranschens Utvecklingsfond)
Note

Dessutom har Zheng Huang, Chao Wang, Niklas Bagge, Jens Häggström, Jonny Nilimaa, Thomas Forsberg,Ola Enokson,Thomas Blanksvärd och Ulf Ohlsson bidragit med material och synpunkteroch som medförfattare i artiklar och konferensbidrag.

Available from: 2017-10-15 Created: 2017-10-15 Last updated: 2022-10-27Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7620-9386

Search in DiVA

Show all publications