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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
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2020 (English)In: Structure and Infrastructure Engineering, ISSN 1573-2479, E-ISSN 1744-8980Article in journal (Refereed) In press
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 Group, 2020
Keywords
Train Bridge Coupling System; Fatigue Damage; Moving Load ( Model; Moving Spring Mass Damper ( Model; Reinforced Concrete Railway Bridge
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-76136 (URN)10.1080/15732479.2019.1671467 (DOI)
Available from: 2019-09-26 Created: 2019-09-26 Last updated: 2019-09-30
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.
Open this publication in new window or tab >>Damage Detection in Structures – Examples
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2019 (English)In: IABSE Symposium 2019: Towards a Resilent Built Environment - Risk and Asset Management, 2019Conference 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.

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)
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: 2019-04-15Bibliographically 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, March 27-29, 2019, Guimarães, Portugal.
Open this publication in new window or tab >>Detection of Sparse Damages in Structures
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2019 (English)In: IABSE Symposium 2019: Towards a Resilent Built Environment - Risk and Asset Management, 2019Conference 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.

Keywords
sparse damage, 𝑙2-norm, 𝑙1-norm, total variation, dictionary-based regularization, sensitivity
National Category
Engineering and Technology Mathematical Analysis Other Civil Engineering
Research subject
Mathematics; Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-73335 (URN)
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: 2019-04-15
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
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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. 43
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: 2019-10-15
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; 20160816 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-09-13Bibliographically 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: 2017-11-24Bibliographically approved
Huang, Z., Grip, N., Sabourova, N., Bagge, N., Tu, Y.-M. & Elfgren, L. (2016). Modelling of Damage and its Use in Assessment of a Prestressed Bridge. Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Modelling of Damage and its Use in Assessment of a Prestressed Bridge
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2016 (English)Report (Other academic)
Abstract [en]

A 55 years old and 121.5 m long ve-span prestressed bridge has been subjected toshear failure test in Kiruna, Sweden. This in-situ test is a desirable test to validate andcalibrate the existing nonlinear nite element program for predicting the shear behaviorof reinforced and prestressed concrete structures.Two 3D nite element (FE) models of the Kiruna Bridge are built in commercial soft-ware Abaqus, one using shell-elements and one using a combination of shell and beam ele-ments. Predictions obtained from these two models are well consistent with mode shapesand eigenfrequencies computed from acceleration measurements on the bridge before andafter loading it to failure. Shear-failure test of this bridge performed by Lulea Universityof Technology (LTU) is also simulated using the built-in concrete damage plasticity (CDP)model in Abaqus. The predicted load-displacement curve is in good agreement with themeasurement. Verication of the CDP model is conducted at element and member levelwith two dierent damage parameter evolutions. According to the verication, it indi-cates the damage parameter will aect the predicted shear behavior of reinforced concretestructures and it is not reliable to adopt the CDP model to simulate the shear behaviorof reinforced concrete structures based on the present research.A long term goal is to use use the measured mode shapes, eigenfrequencies and FEmodels for evaluating methods for damage identication. Such methods are important formaintenance of dierent structures, for extending their life span and for better knowledgeof their load carrying capacity. We describe how so-called sparse regularization niteelement method updating (FEMU) methods can be used. We then demonstrate someimportant properties of such methods with simulations on a Kirchho plate. For instance,the simulations suggest that both eigenfrequencies and mode shapes should be used forprecise localization of the damage.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2016. p. 21
Series
Research report / Luleå University of Technology, ISSN 1402-1528
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-61185 (URN)978-91-7583-820-5 (ISBN)
Available from: 2016-12-21 Created: 2016-12-21 Last updated: 2018-05-22Bibliographically approved
Huang, Z., Tu, Y.-M., Grip, N., Sabourova, N., Bagge, N., Blanksvärd, T., . . . Elfgren, L. (2016). Modelling of Damage and its use in Assessment of a PrestressedConcrete Bridge. In: Lennart Elfgren, Johan Jonsson, Mats Karlsson, Lahja Rydberg-Forssbeck and Britt Sigfrid (Ed.), IABSE CONGRESS, STOCKHOLM, 2016: Challenges in Design and Construction of an Innovativeand Sustainable Built Environment. Paper presented at 19th IABSE Congress, Stockholm 2016, September 21-23 (pp. 2093-2108). CH - 8093 Zürich, Switzerland
Open this publication in new window or tab >>Modelling of Damage and its use in Assessment of a PrestressedConcrete Bridge
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2016 (English)In: IABSE CONGRESS, STOCKHOLM, 2016: Challenges in Design and Construction of an Innovativeand Sustainable Built Environment / [ed] Lennart Elfgren, Johan Jonsson, Mats Karlsson, Lahja Rydberg-Forssbeck and Britt Sigfrid, CH - 8093 Zürich, Switzerland, 2016, p. 2093-2108Conference paper, Published paper (Refereed)
Abstract [en]

A five-span prestressed concrete bridge has been subjected to a loading test up to failure in Kiruna, Sweden. The bridge was 55 years old and had a length of 121.5 m. The test has been used to validate and calibrate existing nonlinear finite element programs for predicting the shear behavior of reinforced and prestressed concrete structures. Two 3D finite element (FE) models of the Kiruna Bridge are built in commercial software Abaqus, one using shell-elements and one using a combination of shell and beam elements. Predictions obtained from these two models are well consistent with mode shapes and eigenfrequencies computed from acceleration measurements on the bridge before and after loading it to failure.The shear failure of the bridge is also simulated using the built-in concrete damage plasticity (CDP)model in Abaqus. The predicted load-displacement curve is in good agreement with the measurements. Verification of the CDP model is conducted at element and member level with two different damage parameter evolutions. The verification indicates that the damage parameter will affect the predicted shear behavior. It does not seem to be reliable to adopt the CDP model to simulate the shear behavior in the present research. A long term goal is to use use the measured mode shapes, eigenfrequencies and FE models for evaluating methods for damage identification. Such methods are important for maintenance of different structures, for extending their life span and for better knowledge of their load carrying capacity. The use is described of so-called sparse regularized finite element method updating (FEMU) methods. Some important properties of such methods are demonstrated using simulations on a Kirchhoff plate. For instance, the simulations suggest that both eigenfrequencies and mode shapes should be used for precise localization of the damage.

Place, publisher, year, edition, pages
CH - 8093 Zürich, Switzerland: , 2016
Series
IABSE Congress Reports
Keywords
Concrete damage plasticity model, refined shell element model, shear failure test, shear behavior, five-span prestressed concrete bridge, FEM updating, sparse regularization, Kirchhoff plate.
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-60996 (URN)2-s2.0-85018991487 (Scopus ID)978-3-85748-144-4 (ISBN)
Conference
19th IABSE Congress, Stockholm 2016, September 21-23
Available from: 2016-12-10 Created: 2016-12-10 Last updated: 2018-03-27Bibliographically approved
Lintzén, N., Almqvist, A. & Grip, N. (2016). Span curve temperature dependence of classic style cross country skis. Sports Technology
Open this publication in new window or tab >>Span curve temperature dependence of classic style cross country skis
2016 (English)In: Sports Technology, ISSN 1934-6182, E-ISSN 1934-6190Article in journal (Refereed) Accepted
National Category
Geotechnical Engineering Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Mathematical Analysis
Research subject
Soil Mechanics; Machine Elements; Mathematics
Identifiers
urn:nbn:se:ltu:diva-59843 (URN)
Available from: 2016-10-19 Created: 2016-10-19 Last updated: 2018-04-19
Edrees, T., Nikolakopoulos, G., Grip, N. & Jonasson, J.-E. (2015). Investigation of changes in modal characteristics before and after damage of a railway bridge: A case study (ed.). Paper presented at . The IES Journal Part A: Civil & Structural Engineering, 8(2), 131-144
Open this publication in new window or tab >>Investigation of changes in modal characteristics before and after damage of a railway bridge: A case study
2015 (English)In: 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) Published
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.

Keywords
Structural Identification, Damage Detection, Non-Destructive Evaluation, Health Monitoring., Civil engineering and architecture - Building engineering, Samhällsbyggnadsteknik och arkitektur - Byggnadsteknik
National Category
Infrastructure Engineering Control Engineering Mathematical Analysis
Research subject
Structural Engineering; Control Engineering; Mathematics
Identifiers
urn:nbn:se:ltu:diva-3067 (URN)10.1080/19373260.2015.1020889 (DOI)2-s2.0-84928928602 (Scopus ID)0d4f141e-c90a-46ec-8522-13749de68d77 (Local ID)0d4f141e-c90a-46ec-8522-13749de68d77 (Archive number)0d4f141e-c90a-46ec-8522-13749de68d77 (OAI)
Note
Validerad; 2015; Nivå 1; 20150217 (taredr)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7620-9386

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