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Huang, Z., Tu, Y., Meng, S., Bagge, N., Nilimaa, J. & Blanksvärd, T. (2019). Validation of a numerical method for predicting shear deformation of reinforced concrete beams. Engineering structures, 197, Article ID 109367.
Open this publication in new window or tab >>Validation of a numerical method for predicting shear deformation of reinforced concrete beams
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2019 (English)In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 197, article id 109367Article in journal (Refereed) Published
Abstract [en]

The objective of this paper is to validate a 2D nonlinear finite element (FE) model for estimating the post-cracking shear deformation of reinforced concrete (RC) beams. The proposed FE model treated the cracked concrete as an orthotropic material in the framework of the fixed-crack approach. The experimental data for both the overall response (including the total and shear-induced deflection) and the detailed response (including the mean shear strain, mean vertical strain and principal compressive strain angle) of five I-section RC beams, monitored by the main authors of this paper with the Digital Image Correlation technique, were used to verify the proposed model. In addition, 27 further test beams evaluated in independent research programs were collected to assemble a database. The proposed FE model was further verified against the database. Two additional FE models (the rotating-crack model developed in this work and Response-2000 developed by Bentz (2000)) were also evaluated by simulating the detailed responses of the beams in the database. The results obtained validate the proposed FE model for predicting the post-cracking shear deformation of RC beams and indicate that the proposed FE model is more suitable for simulating the shear behaviour of RC beams than the rotating-crack model or Response-2000.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Reinforced concrete beams, Shear deformation, Nonlinear finite element model, Model verification, Digital image correlation
National Category
Engineering and Technology Other Civil Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-75389 (URN)10.1016/j.engstruct.2019.109367 (DOI)
Note

Validerad;2019;Nivå 2;2019-08-14 (johcin)

Available from: 2019-08-05 Created: 2019-08-05 Last updated: 2019-08-14Bibliographically approved
Nilimaa, J., Sabau, C., Bagge, N., Puurula, A., Sas, G., Blanksvärd, T., . . . Elfgren, L. (2018). Assessment and Loading to Failure of Three Swedish RC Bridges. In: Eva Lantsoght and Pinar Okumus (Ed.), Evaluation of Concrete Bridge Behavior through Load Testing: International Perspectives (pp. 8.1-8.18). Faarmington Hills, MI: American Concrete Institute, 323, Article ID SP-323-8.
Open this publication in new window or tab >>Assessment and Loading to Failure of Three Swedish RC Bridges
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2018 (English)In: Evaluation of Concrete Bridge Behavior through Load Testing: International Perspectives / [ed] Eva Lantsoght and Pinar Okumus, Faarmington Hills, MI: American Concrete Institute, 2018, Vol. 323, p. 8.1-8.18, article id SP-323-8Chapter in book (Refereed)
Abstract [en]

Current codes often underestimate the capacity of existing bridges. The purpose of the tests presented here has been to assess the real behaviour and capacity of three types of bridges in order to be able to utilize them in a more efficient way.

The three studied bridges are: (1) Lautajokk – A one-span trough bridge tested in fatigue to check the shear capacity of the section between the slab and the girders; (2) Övik – A two span trough bridge strengthened with Near Surface Mounted Reinforcement (NSMR) of Carbon Fibre Reinforced Polymers (CFRP) tested in bending, shear and torsion; and (3) Kiruna – A five-span prestressed three girder bridge tested to shear-bending failures in the girders and in the slab.

The failure capacities were considerably higher than what the code methods indicated. With calibrated and stepwise refined finite element models, it was possible to capture the real behaviour of the bridges. The experiences and methods may be useful in assessment and better use of other bridges.

Place, publisher, year, edition, pages
Faarmington Hills, MI: American Concrete Institute, 2018
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-69992 (URN)978-1-64195-007-7 (ISBN)
Available from: 2018-06-29 Created: 2018-06-29 Last updated: 2018-08-10Bibliographically approved
Täljsten, B., Blanksvärd, T., Sas, G., Bagge, N., Nilimaa, J., Popescu, C., . . . Häggström, J. (2018). Bridges tested to failure in Sweden. In: IABSE Conference 2018 – Engineering the Past, to Meet the Needs of the FutureJune 25-27 2018, Copenhagen, Denmark: . Paper presented at IABSE Conference 2018 – Engineering the Past, to Meet the Needs of the Future June 25-27 2018, Copenhagen, Denmark.
Open this publication in new window or tab >>Bridges tested to failure in Sweden
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2018 (English)In: IABSE Conference 2018 – Engineering the Past, to Meet the Needs of the FutureJune 25-27 2018, Copenhagen, Denmark, 2018Conference paper, Published paper (Refereed)
Abstract [en]

Five bridges of different types have been tested to failure and the results have been compared to analyses of the load-carrying capacity using standard code models and advanced numerical methods. The results may help to make accurate assessments of similar existing bridges. There it is necessary to know the real behaviour, weak points, and to be able to model the load-carrying capacity in a correct way.The five bridges were: (1) a strengthened one span concrete road bridge - Stora Höga ; (2) a one span concrete rail trough bridge loaded in fatigue – Lautajokk; (3) a two span strengthened concrete trough railway bridge - Övik; (4) a one span railway steel truss bridge -Åby; and (5) a five span prestressed concrete road bridge - Kiruna. The unique results in the paper are the experiences of the real failure types, the robustness/weakness of the bridges, and the accuracy and shortcomings/potentials of different codes and models for safety assessment of existing structures

Keywords
Test to failure, bridges of concrete and steel, Assessment, Strengthening, Monitoring, Bending, Shar, Torsion, Bond, Fatigue, Carbon Fibre Reinforced Polymers (CFRP)
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-72378 (URN)
Conference
IABSE Conference 2018 – Engineering the Past, to Meet the Needs of the Future June 25-27 2018, Copenhagen, Denmark
Available from: 2018-12-28 Created: 2018-12-28 Last updated: 2019-09-06
Duvnjak, I., Bartolak, M., Nilimaa, J., Sas, G., Blanksvärd, T., Täljsten, B. & Elfgren, L. (2018). Lessons Learnt from Full-Scale Tests of Bridges in Croatia and Sweden. In: IABSE Symposium, Nantes 2018: Tomorrow's Megastructures. Paper presented at 40th IABSE Symposium, 19-21 September 2018, Nantes, France.. International Association for Bridge and Structural Engineering, Article ID S23-127.
Open this publication in new window or tab >>Lessons Learnt from Full-Scale Tests of Bridges in Croatia and Sweden
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2018 (English)In: IABSE Symposium, Nantes 2018: Tomorrow's Megastructures, International Association for Bridge and Structural Engineering , 2018, article id S23-127Conference paper, Published paper (Refereed)
Abstract [en]

Load testing is a way to control the capacity and function of a bridge. Methods and recommendations for load testing are described and examples are given form tests carried out in Croatia and Sweden. In order not to damage the bridge being tested, the load must be limited, often to be within the serviceability limit state (SLS). Numerical models can be calibrated by load tests and then be used to check the carrying capacity for higher loads than what has been tested. Need for further work and recommendations are discussed. By effective planning, costs can be saved and a more sustainable use of bridges can be obtained.

Place, publisher, year, edition, pages
International Association for Bridge and Structural Engineering, 2018
Keywords
Load testing, proof loading, collapse, deformations, serviceability limit state (SLS), numerical modelling, stiffness
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-72381 (URN)2-s2.0-85059365622 (Scopus ID)9783857481611 (ISBN)
Conference
40th IABSE Symposium, 19-21 September 2018, Nantes, France.
Funder
EU, Horizon 2020
Available from: 2018-12-28 Created: 2018-12-28 Last updated: 2019-01-14Bibliographically approved
Bagge, N., Nilimaa, J., Blanksvärd, T., Täljsten, B., Elfgren, L., Sundquist, H. & Carolin, A. (2017). Assessment and failure test of a prestressed concrete bridge. In: Jaap Bakker; Dan M Frangopol; Klaas van Breugel (Ed.), Life-Cycle of Engineering Systems: Emphasis on Sustainable Civil Infrastructure. Paper presented at 5th International Symposium on Life-Cycle Engineering, IALCCE 2016, Delft, Netherlands, 16-20 October 2016 (pp. 1058-1063). Leiden: CRC Press/Balkema
Open this publication in new window or tab >>Assessment and failure test of a prestressed concrete bridge
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2017 (English)In: Life-Cycle of Engineering Systems: Emphasis on Sustainable Civil Infrastructure / [ed] Jaap Bakker; Dan M Frangopol; Klaas van Breugel, Leiden: CRC Press/Balkema , 2017, p. 1058-1063Conference paper, Published paper (Refereed)
Abstract [en]

Tests have been carried out at service- and ultimate load levels of a 55 year-old prestressed concrete girder bridge. The bridge, located in Kiruna, Sweden, was continuous in five spans with a total length of 121.5 m. The overall aim of the study was to determinate the accuracy of assessment methods for existing structures and to provide procedures for optimized assessment. Before the tests a 2D finite element (FE) analysis was performed to predict the behavior and load-carrying capacity of the bridge. In order to more accurately assess the bridge response a 3D FE model has now been developed. The actual loading history and material properties has been considered in the model. A Life Cycle Cost Assessment of the bridge has also been performed

Place, publisher, year, edition, pages
Leiden: CRC Press/Balkema, 2017
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-63448 (URN)2-s2.0-85018632781 (Scopus ID)9781138028470 (ISBN)
Conference
5th International Symposium on Life-Cycle Engineering, IALCCE 2016, Delft, Netherlands, 16-20 October 2016
Available from: 2017-05-19 Created: 2017-05-19 Last updated: 2018-03-26Bibliographically approved
Bagge, N., Nilimaa, J., Puurula, A., Täljsten, B., Blanksvärd, T., Sas, G., . . . Carolin, A. (2017). Full-Scale Tests to Failure Compared to Assessments: Three Concrete Bridges. In: Hordijk D.A., Luković M. (Ed.), Lukovic M.,Hordijk D.A. (Ed.), High Tech Concrete: Where Technology and Engineering Meet - Proceedings of the 2017 fib Symposium. Paper presented at 2017 fib Symposium - High Tech Concrete: Where Technology and Engineering Meet, Maastricht, Netherlands, 12-14 June 2017 (pp. 1917-1924). Cham: Springer
Open this publication in new window or tab >>Full-Scale Tests to Failure Compared to Assessments: Three Concrete Bridges
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2017 (English)In: High Tech Concrete: Where Technology and Engineering Meet - Proceedings of the 2017 fib Symposium / [ed] Lukovic M.,Hordijk D.A., Cham: Springer, 2017, p. 1917-1924Conference paper, Published paper (Refereed)
Abstract [en]

Three Swedish concrete bridges have been tested to failure and the results have been compared to assessment using standard code models and advanced numerical methods.

The three tested and assessed bridges were:

  1. (1)

    Lautajokk, a 29 year old one span (7 m) concrete trough bridge tested in fatigue to check the concrete shear capacity.

     
  2. (2)

    Ӧrnskldsvik, a 50 year old two span trough bridge (12 + 12 m) strengthened to avoid a bending failure.

     
  3. (3)

    Kiruna Mine Bridge, a 55 year old five span prestressed concrete road bridge (18 + 21 + 23 + 24 + 20 m) tested in shear and bending of the beams and punching of the slab.

     

The main results in the paper are the experiences of the real failure types, the robustness/weakness of the bridges, and the accuracy of different codes and models. In all three cases the bridges had a considerable hidden capacity.

Place, publisher, year, edition, pages
Cham: Springer, 2017
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-63917 (URN)10.1007/978-3-319-59471-2_219 (DOI)2-s2.0-85025656710 (Scopus ID)978-3-319-59470-5 (ISBN)978-3-319-59471-2 (ISBN)
Conference
2017 fib Symposium - High Tech Concrete: Where Technology and Engineering Meet, Maastricht, Netherlands, 12-14 June 2017
Available from: 2017-06-12 Created: 2017-06-12 Last updated: 2018-03-26Bibliographically approved
Bagge, N., Nilimaa, j. & Elfgren, L. (2017). In-situ methods to determine residual prestress forces in concrete bridges. Engineering structures, 135, 41-52
Open this publication in new window or tab >>In-situ methods to determine residual prestress forces in concrete bridges
2017 (English)In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 135, p. 41-52Article in journal (Refereed) Published
Abstract [en]

Levels of residual prestress forces are key parameters when assessing the structural behaviour of existing prestressed concrete bridges. However, these parameters are often unknown and not easy to determine. To explore them, two existing non-destructive and destructive approaches have been further developed for practical application and demonstrated on a multi-span continuous girder bridge. The evaluation of the prestress forces was part of an extensive experimental programme aimed to calibrate and develop assessment methods. Due to the pursuit of practical applications for existing bridges, the main focus was on non-destructive methodology, combining experimental data and finite element modelling to obtain the residual prestress forces. Assuming that the initial prestress force corresponded to 85% of the characteristic 0.2% proof strength of the reinforcing steel, estimated losses in investigated sections ranged between 5 and 70%. However, determined residual prestress forces were generally higher than theoretically based estimates accounting for friction and time-dependent losses in the prestressing system. In addition to describing in detail the methods for prestress evaluation, this paper presents suggestions for improvements and further studies, based on experiences from the field tests.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-61348 (URN)10.1016/j.engstruct.2016.12.059 (DOI)000394191000004 ()2-s2.0-85008703720 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-01-10 (andbra)

Available from: 2017-01-10 Created: 2017-01-10 Last updated: 2018-09-13Bibliographically approved
Häggström, J., Bagge, N., Nilimaa, J., Sas, G., Blanksvärd, T., Täljsten, B., . . . Carolin, A. (2017). Testing Bridges to Failure: Experiences. In: IABSE Symposium, Vancouver, 2017: Engineering the Future. Paper presented at 39th IABSE Symposium, Engineering the Future, Vancouver, Canada, Sept 21-23, 2017 (pp. 2832-2839). Zürich, Switzerland: IABSE - International Association for Bridges and Structural Engineering
Open this publication in new window or tab >>Testing Bridges to Failure: Experiences
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2017 (English)In: IABSE Symposium, Vancouver, 2017: Engineering the Future, Zürich, Switzerland: IABSE - International Association for Bridges and Structural Engineering , 2017, p. 2832-2839Conference paper, Published paper (Refereed)
Abstract [en]

Four bridges of different types have been tested to failure and the results have been compared to the load-carrying capacity calculated using standard code models and advanced numerical methods. The results may help to make accurate assessments of similar existing bridges. Here it is necessary to know the real behaviour, weak points, and to be able to model the load-carrying capacity in a correct way.

The four bridges were: (1) a one span steel truss railway bridge; (2) a two span strengthened concrete trough railway bridge; (3) a one span concrete trough bridge tested in fatigue; and (4) a five span prestressed concrete road bridge.

The unique results in the paper are the experiences of the real failure types, the robustness/weakness of the bridges, and the accuracy of different codes and models.

Place, publisher, year, edition, pages
Zürich, Switzerland: IABSE - International Association for Bridges and Structural Engineering, 2017
Keywords
bridges, testing, assessment, load-carrying capacity, reinforced concrete, prestressed concrete, steel, analysis, codes
National Category
Transport Systems and Logistics Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-66134 (URN)2-s2.0-85050030469 (Scopus ID)978-3-85748-153-6 (ISBN)
Conference
39th IABSE Symposium, Engineering the Future, Vancouver, Canada, Sept 21-23, 2017
Funder
EU, FP7, Seventh Framework ProgrammeSwedish Transport Administration
Available from: 2017-10-15 Created: 2017-10-15 Last updated: 2018-08-08Bibliographically approved
Nilimaa, J., Hösthagen, A. & Emborg, M. (2017). Thermal Crack Risk of Concrete Structures: Evaluation of Theoretical Models for Tunnels and Bridges. Nordic Concrete Research, 56(1), 55-69
Open this publication in new window or tab >>Thermal Crack Risk of Concrete Structures: Evaluation of Theoretical Models for Tunnels and Bridges
2017 (English)In: Nordic Concrete Research, ISSN 0800-6377, Vol. 56, no 1, p. 55-69Article in journal (Refereed) Published
Abstract [en]

An approach for thermal crack risk estimations was introduced in the Swedish design guidelines BRO 94. The cracking occurs during the early hardening process because of the exothermic reactions between water and cement and often result in high repair costs and delayed construction. This paper studies and validates the inherent safety levels for one typical case of concrete structure. Three slab-frame structures were analysed and the original crack risk estimations were compared to the actual cracking and postcalculations were carried out, using actual parameters. This paper shows that walls with computed strain ratios over 70% were affected by thermal cracks.

Place, publisher, year, edition, pages
Nordic Concrete Federation, 2017
Keywords
Thermal cracking, Structural Design, Sustainability, Concrete tunnels
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-64967 (URN)000425406000006 ()
Note

Validerad;2017;Nivå 1;2017-08-16 (rokbeg)

Available from: 2017-08-07 Created: 2017-08-07 Last updated: 2018-06-20Bibliographically approved
Bagge, N., Nilimaa, J. & Elfgren, L. (2016). Evaluation of residual prestress force in a concrete girder 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 9th IABSE Congress, Stockholm 2016, September 21-23 (pp. 222-229). CH - 8093 Zürich, Switzerland
Open this publication in new window or tab >>Evaluation of residual prestress force in a concrete girder bridge
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. 222-229Conference paper, Published paper (Refereed)
Abstract [en]

When assessing the structural behaviour of prestressed concrete bridges, understanding the level of prestressing is crucial. However, for existing structures, this is usually an unknown parameter and the literature only describes a few methods of experimentally determining the residual prestress forces. For this paper, a non-destructive testing approach has been evaluated based on testing of a multi-span continuous girder bridge. The method, consisting of in-situ measurements in combination with finite element (FE) simulations, revealed prestress levels in the range 25 % to 82 % of the reinforcement steel yield strength, depending on the section tested. A comparison with theoretically calculated residual prestress forces, taking into account friction and timedependent losses, indicated values of the same order but with some inconsistencies.

Place, publisher, year, edition, pages
CH - 8093 Zürich, Switzerland: , 2016
Series
IABSE Congress Reports
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-63562 (URN)2-s2.0-85018989242 (Scopus ID)978-3-85748-144-4 (ISBN)
Conference
9th IABSE Congress, Stockholm 2016, September 21-23
Available from: 2017-05-29 Created: 2017-05-29 Last updated: 2018-03-26Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1398-6118

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