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Publications (10 of 32) Show all publications
Min, X., Zhang, J., Tu, Y., Li, X., Wang, C., Sas, G. & Elfgren, L. (2024). A full-range fatigue life prediction model for RC beams strengthened with prestressed CFRP plates accounting for the impact of FRP debonding. Engineering structures, 301, Article ID 117305.
Open this publication in new window or tab >>A full-range fatigue life prediction model for RC beams strengthened with prestressed CFRP plates accounting for the impact of FRP debonding
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2024 (English)In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 301, article id 117305Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Elsevier, 2024
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-103512 (URN)10.1016/j.engstruct.2023.117305 (DOI)001139402800001 ()2-s2.0-85179467577 (Scopus ID)
Note

Validerad;2024;Nivå 2;2024-01-19 (signyg);

Funder: Natural Science Foundation of Jiangsu Province of China (grant nos. BK20230703); the Scientific Research Foundation of Nanjing Institute of Technology (grant nos. YKJ202122); the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (23KJB560010); National Key Research and Development Program of China (grant nos. 2017YFC0703006-01); Array (2017YFC0703006-01)

Available from: 2024-01-08 Created: 2024-01-08 Last updated: 2024-04-04Bibliographically approved
Wang, C., Zhang, J., Gonzalez-Libreros, J., Tu, Y., Elfgren, L. & Sas, G. (2024). A quantitative residual stiffness model for carbon fiber reinforced polymer tendons. Fatigue & Fracture of Engineering Materials & Structures, 47(6), 2068-2084
Open this publication in new window or tab >>A quantitative residual stiffness model for carbon fiber reinforced polymer tendons
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2024 (English)In: Fatigue & Fracture of Engineering Materials & Structures, ISSN 8756-758X, E-ISSN 1460-2695, Vol. 47, no 6, p. 2068-2084Article in journal (Refereed) Published
Abstract [en]

In this study, tension-tension fatigue tests were conducted to investigate the residual stiffness degradation of carbon fiber-reinforced polymer (CFRP) tendons. Different stress levels were used in the tests, and measurements of residual stiffness and the number of loading cycles were taken. Based on experimental data for CFRP tendons, a quantitative residual stiffness model was developed by modifying Yao's model. This model is applicable to various stress levels. To assess its accuracy and applicability, the predicted results of this model were compared with those of cited models from other researchers. The findings revealed a three-stage degradation of residual stiffness in CFRP tendons under different stress levels. Furthermore, it was observed that the proportion of fatigue life accounted for by Stage III decreased with smaller stress ranges, while the proportion accounted for by Stage II increased. The proposed quantitative residual stiffness model was verified using both experimental and cited data. Tension-tension fatigue tests of CFRP tendons were conducted at various stress levels. A quantitative model was proposed based on the residual stiffness of the CFRP tendon. Stress level influence on stiffness degradation of composite material was discussed. Model accuracy was verified against experimental and cited data.

Place, publisher, year, edition, pages
John Wiley & Sons, 2024
Keywords
carbon fiber reinforced polymer (CFRP) tendon, quantitative model, residual stiffness, three-stage degradation
National Category
Composite Science and Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-105004 (URN)10.1111/ffe.14290 (DOI)001194229500001 ()2-s2.0-85189614627 (Scopus ID)
Funder
Swedish Research Council Formas, 2023-01443
Note

Validerad;2024;Nivå 2;2024-05-21 (joosat);

Funder: National Key Research and Development Program of China (2017YFC0703006-01);

Full text license: CC BY

Available from: 2024-04-08 Created: 2024-04-08 Last updated: 2024-05-21Bibliographically approved
Agredo Chávez, A., Gonzalez-Libreros, J., Wang, C., Capacci, L., Biondini, F., Elfgren, L. & Sas, G. (2024). Assessment of residual prestress in existing concrete bridges: The Kalix bridge. Engineering structures, 311, Article ID 118194.
Open this publication in new window or tab >>Assessment of residual prestress in existing concrete bridges: The Kalix bridge
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2024 (English)In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 311, article id 118194Article in journal (Refereed) Published
Abstract [en]

The direct socio-economic consequences of the deterioration of aging infrastructure systems have triggered a continuous process of revising and updating current design standards and guidelines for critical network components. Specifically, long-term degradation processes demand the analysis and evaluation of vital structural assets such as prestressed concrete bridges. It is crucial to develop theoretically consistent, user-friendly, and non-destructive methodologies that engineering professionals can employ to prevent and mitigate potential catastrophic outcomes during the service life of these bridges. This study provides a thorough review of the available testing methods employed over the years for prestressed concrete bridges and introduces a comprehensive framework for evaluating existing methods for residual prestress force assessment. Through a multi-criteria selection process, the three most feasible tests were designed and carried out on an existing 66-year-old balanced cantilever box girder bridge exposed to freezing temperatures that affected the instrumentation plan and test execution. Finally, predictive models compliant with standard codes were calibrated based on the experimental results and the life cycle loss of prestress forces was evaluated to assess relevant bounding intervals. Findings reveal limited on-site testing and discrepancies between calculated residual forces and predictions by standard codes. The saw cut method showed a 18% difference from the initial applied prestress according to the prestress protocol, suggesting the use of a cover meter and concrete modulus evaluation for improved accuracy. The strand cutting method resulted in a 14% difference, emphasizing the need for stress redistribution assessment. The second-order deflection method showed a 6% difference, indicating a focus on enhanced boundary conditions and thorough sensitivity analysis for future investigations.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Box girder, Concrete bridges, Diagnostics, Experimental tests, Residual prestress, Structural assessment
National Category
Infrastructure Engineering Building Technologies
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-105634 (URN)10.1016/j.engstruct.2024.118194 (DOI)2-s2.0-85193552116 (Scopus ID)
Funder
Svenska Byggbranschens Utvecklingsfond (SBUF)Swedish Transport Administration
Note

Validerad;2024;Nivå 2;2024-05-31 (hanlid);

Funder: Interreg Aurora; 

Full text license: CC BY

Available from: 2024-05-31 Created: 2024-05-31 Last updated: 2024-05-31Bibliographically approved
Fang, M., Wang, T., Guo, T., Shi, P., Jiang, B., Wang, C., . . . Elfgren, L. (2024). Compressive reactive molecular dynamics on mechanical and structural behaviors of geopolymers: Imposing lateral constraints and varied temperatures. Applied Clay Science, 249, Article ID 107257.
Open this publication in new window or tab >>Compressive reactive molecular dynamics on mechanical and structural behaviors of geopolymers: Imposing lateral constraints and varied temperatures
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2024 (English)In: Applied Clay Science, ISSN 0169-1317, E-ISSN 1872-9053, Vol. 249, article id 107257Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Elsevier Ltd, 2024
National Category
Other Materials Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-103908 (URN)10.1016/j.clay.2024.107257 (DOI)001161999800001 ()2-s2.0-85182403837 (Scopus ID)
Note

Validerad;2024;Nivå 2;2024-02-16 (joosat);

Funder: National Natural Science Foundation of China (51378104, U23A20661); Jiangsu Province (BZ2021011); Fundamental Research Funds for the Central Universities (2242022k30030, 2242022k30031); National Science Fund for Distinguished Young Scholars (52125802);

Available from: 2024-01-24 Created: 2024-01-24 Last updated: 2024-03-07Bibliographically approved
(2024). Condition Assessment of Existing Bridges: A Case Study of The Kalix Bridge. Luleå: Luleå University of Technology
Open this publication in new window or tab >>Condition Assessment of Existing Bridges: A Case Study of The Kalix Bridge
2024 (English)Report (Other academic)
Abstract [en]

This document is the final report for project BBT 2020-013 (Trafikverket). It presents the results for the development and testing of a loading system based on realistic convoy loads for serviceability limit state (SLS) applied to the Kalix Bridge. It also includes a determination of the bridge condition through non-destructive testing (NDT) and assessment of non-destructive methods for the determination of residual prestressing forces. The work carried out included the development of linear and non-linear finite element models and their calibration, based on the information collected in the experimental part. Digital twin models intended for the prediction of bridge response were also created, and novel AI-based methods for crack detection were evaluated. In addition, a framework for condition management based on reliability and robustness parameters was developed within the scope of the project. As the Kalix Bridge was replaced by a new structure in 2022, the report summarizes a comprehensive review of methods for demolition of prestressed bridges and presents a methodology for demolition based on numerical analysis of the structure, considering the specific characteristics of the project and existing information about the bridge.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2024. p. 214
Series
Research report / Luleå University of Technology, ISSN 1402-1528
Keywords
Kalix bridge, prestressed concrete bridges, existing bridges, testbed, assessment, NDT, digital twin, demolition, non-destructive methods, crack detection, reliability, robustness
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-105570 (URN)978-91-8048-586-9 (ISBN)978-91-8048-585-2 (ISBN)
Projects
BBT 2020-013 (Trafikverket)
Note

Authors of the specific chapters in the report:

Chapter 1: Gabriel Sas - Chapter 2: Silvia Sarmiento, Lennart Elfgren - Chapter 3: Jaime Gonzalez-Libreros, Chao Wang, Cosmin Daescu - Chapter 4: Angelica Agredo, Silvia Sarmiento, Ali Mirzazade, Jaime Gonzalez-Libreros - Chapter 5: Angelica Agredo, Silvia Sarmiento, Ali Mirzazade, Jaime Gonzalez-Libreros, Cosmin Popescu, Björn Täljsten, Bård Arntsen, Mats Holmqvist, Syed Abrar, Imran Tamboli, Sanat Wable, Werner Bjerke, Kamal Raj Chapagain Raid Karoumi, Gabriel del Pozo - Chapter 6: Mario Plos, Kamyab Zandi - Chapter 7: Kamyab Zandi - Chapter 8: Silvia Sarmiento, Sebastian Thöns, Ivar Björnsson - Chapter 9: Cosmin Daescu, Jaime Gonzalez-Libreros, Chao Wang - Chapter 10: Jaime Gonzalez-Libreros, Gabriel Sas - Chapter 11: Jaime Gonzalez-Libreros, Gabriel Sas

Funders: FOI-BBT (Trafikverket); SBUF (NCC); Statens Vegvesen

Available from: 2024-05-22 Created: 2024-05-22 Last updated: 2024-07-02Bibliographically approved
Liu, D., Wang, C., Gonzalez-Libreros, J., Tu, Y., Elfgren, L. & Sas, G. (2024). Modified calculation model of train-induced aerodynamic pressure on vertical noise barriers considering the train geometry effect. Journal of Wind Engineering and Industrial Aerodynamics, 249, Article ID 105750.
Open this publication in new window or tab >>Modified calculation model of train-induced aerodynamic pressure on vertical noise barriers considering the train geometry effect
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2024 (English)In: Journal of Wind Engineering and Industrial Aerodynamics, ISSN 0167-6105, E-ISSN 1872-8197, Vol. 249, article id 105750Article in journal (Refereed) Published
Abstract [en]

High-speed trains (HSTs) generate air disturbance, leading to significant aerodynamic pressure on the noise barriers. Differences in train geometry result in variations in the aerodynamic pressure on noise barriers, implying that existing European standard calculation models may not necessarily be suitable for all types of HSTs. In this paper, the influence of the width, height, and nose length of the train on the aerodynamic pressure on vertical noise barriers was studied using computational fluid dynamics (CFD) simulations. Results showed that taller and wider trains result in greater aerodynamic loads on noise barriers. Conversely, an increase in the nose length of a train leads to a reduction in such pressure. Using grey relational analysis, correlation of various factors with the train-induced aerodynamic pressure is, from strong to weak: distance to the track center, width, height, and nose length of the train. Building upon the EN 14067-4 calculation model, the shape coefficients of trains with varying geometric characteristics were derived using the simulation data obtained in this study. A modified pressure calculation model was established accounting for the differences in geometric features of HSTs and pressure distribution in the vertical direction of noise barriers and validated using relevant data from the literature.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Aerodynamic pressure, Computational fluid dynamics simulation, Pressure calculation model, Train geometry, Vertical noise barrier
National Category
Fluid Mechanics and Acoustics
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-101567 (URN)10.1016/j.jweia.2024.105750 (DOI)2-s2.0-85191294975 (Scopus ID)
Funder
Swedish Transport Administration, BBT-2019-022
Note

Validerad;2024;Nivå 2;2024-06-28 (joosat);

Full text: CC BY License

Available from: 2023-10-04 Created: 2023-10-04 Last updated: 2024-06-28Bibliographically approved
Tu, Y., Wang, T., Wen, R., Cao, J., Fang, M., Wang, C., . . . Elfgren, L. (2024). Molecular dynamics study on the adsorption of radioactive ions by geopolymers. Advances in Cement Research, 36(3), 129-141
Open this publication in new window or tab >>Molecular dynamics study on the adsorption of radioactive ions by geopolymers
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2024 (English)In: Advances in Cement Research, ISSN 0951-7197, E-ISSN 1751-7605, Vol. 36, no 3, p. 129-141Article in journal (Refereed) Published
Place, publisher, year, edition, pages
ICE Publishing, 2024
National Category
Other Chemical Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-99416 (URN)10.1680/jadcr.22.00085 (DOI)001024535500001 ()2-s2.0-85164507020 (Scopus ID)
Note

Validerad;2024;Nivå 2;2024-04-05 (joosat);

Funder: National Natural Science Foundation of China (51378104); Jiangsu Province (BZ2021011); Fundamental Research Funds for the Central Universities (2242022k30030, 2242022k30031)

Available from: 2023-08-09 Created: 2023-08-09 Last updated: 2024-04-05Bibliographically approved
Tu, Y., Jiang, B., Guo, T., Fang, M., Wang, T., Shi, P., . . . Sas, G. (2024). Nanoscale insights into NASH under high-velocity fluids erosion: A molecular dynamics study. Journal of Building Engineering, 94, Article ID 109830.
Open this publication in new window or tab >>Nanoscale insights into NASH under high-velocity fluids erosion: A molecular dynamics study
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2024 (English)In: Journal of Building Engineering, E-ISSN 2352-7102, Vol. 94, article id 109830Article in journal (Refereed) Published
Abstract [en]

The poor durability of geopolymer is a major factor hindering its application, and erosion from high-velocity fluids exacerbates this drawback. This study aimed to characterize the microstructural features of geopolymer under high-velocity fluids erosion and investigate the influence of harmful ions on erosion damage. Models of geopolymer/water solution and geopolymer/NaCl solution were constructed to simulate the erosion of geopolymer by high-velocity fluids. The results indicated that under high-velocity fluids erosion, most of the atoms on the surface of the geopolymer experienced leaching, indicating destruction of the substrate. Additionally, water molecules in solution were able to form hydrogen bonds to the substrate surface, accelerating its degradation. Under NaCl solution erosion, Na ions interacted with the exposed bridging oxygen in the geopolymer, and ion exchange occurred between Na ions and the substrate, making the substrate more unstable and leaching more pronounced. The findings of this study provide nanoscale insights into the erosion resistance of geopolymer that could guide the development of new erosion-resistant materials and methods.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
High-velocity fluids, Molecular dynamics, Sea water, Sodium aluminosilicate hydrate
National Category
Mechanical Engineering Physical Sciences Chemical Sciences
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-108261 (URN)10.1016/j.jobe.2024.109830 (DOI)2-s2.0-85196732589 (Scopus ID)
Note

Validerad;2024;Nivå 2;2024-07-03 (hanlid);

Funder: National Natural Science Foundation of China (51378104); National Science Fund for Distinguished Young Scholars (52125802); Policy guidance plan of Jiangsu Province (BZ2021011); Fundamental Research Funds for the Central Universities (2242022k30030, 2242022k30031)

Available from: 2024-07-03 Created: 2024-07-03 Last updated: 2024-07-03Bibliographically approved
Wang, T., Cao, J., Guo, T., Tu, Y., Wang, C., Sas, G. & Elfgren, L. (2024). The role of deep learning in reducing computational cost when simulating chloride ion attack on hydrated calcium silicate with molecular dynamics. Construction and Building Materials, 417, Article ID 135257.
Open this publication in new window or tab >>The role of deep learning in reducing computational cost when simulating chloride ion attack on hydrated calcium silicate with molecular dynamics
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2024 (English)In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 417, article id 135257Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Elsevier Ltd, 2024
National Category
Other Civil Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-104320 (URN)10.1016/j.conbuildmat.2024.135257 (DOI)2-s2.0-85184522280 (Scopus ID)
Note

Validerad;2024;Nivå 2;2024-02-20 (joosat);

Funder: Natural Science Foundation of China [grant numbers 51378104]; National Science Fund for Distinguished Young Scholars [grant numbers 52125802]; "One belt, one road" innovation cooperation project, Jiangsu Province [grant numbers BZ2021011]; Fundamental Research Funds for the Central Universities [grant numbers 2242022k30030, 2242022k30031];

Available from: 2024-02-20 Created: 2024-02-20 Last updated: 2024-02-20Bibliographically approved
Liu, D., Wang, C., Guo, T., Gonzalez-Libreros, J., Ge, Y., Tu, Y., . . . Sas, G. (2024). Time–depth dependent chloride diffusion coefficient of self-compacting concrete. Magazine of Concrete Research, 76(12), 600-616
Open this publication in new window or tab >>Time–depth dependent chloride diffusion coefficient of self-compacting concrete
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2024 (English)In: Magazine of Concrete Research, ISSN 0024-9831, E-ISSN 1751-763X, Vol. 76, no 12, p. 600-616Article in journal (Refereed) Published
Place, publisher, year, edition, pages
ICE Publishing, 2024
National Category
Civil Engineering Materials Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-103740 (URN)10.1680/jmacr.23.00237 (DOI)001134369300001 ()2-s2.0-85180960487 (Scopus ID)
Note

Validerad;2024;Nivå 2;2024-05-21 (joosat);

Available from: 2024-01-16 Created: 2024-01-16 Last updated: 2024-05-21Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-0089-8140

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