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Ansell, Anders
Publications (10 of 12) Show all publications
Eriksson, D., Gasch, T. & Ansell, A. (2019). A Hygro-Thermo-Mechanical Multiphase Model for Long-Term Water Absorption into Air-Entrained Concrete. Transport in Porous Media, 127(1), 113-141
Open this publication in new window or tab >>A Hygro-Thermo-Mechanical Multiphase Model for Long-Term Water Absorption into Air-Entrained Concrete
2019 (English)In: Transport in Porous Media, ISSN 0169-3913, E-ISSN 1573-1634, Vol. 127, no 1, p. 113-141Article in journal (Refereed) Published
Abstract [en]

Many concrete structures located in cold climates and in contact with free water are cast with air-entrained concrete. The presence of air pores significantly affects the absorption of water into the concrete, and it may take decades before these are fully saturated. This generally improves the long-term performance of such structures and in particular their frost resistance. To study the long-term moisture conditions in air-entrained concrete, a hygro-thermo-mechanical multiphase model is presented, where the rate of filling of air pores with water is described as a separate diffusion process. The driving potential is the concentration of dissolved air, obtained using an averaging procedure with the air pore size distribution as the weighting function. The model is derived using the thermodynamically constrained averaging theory as a starting point. Two examples are presented to demonstrate the capabilities and performance of the proposed model. These show that the model is capable of describing the complete absorption process of water in air-entrained concrete and yields results that comply with laboratory and in situ measurements.

Place, publisher, year, edition, pages
Netherlands: Springer, 2019
Keywords
Air-entrained concrete, Multiphase model, Long-term absorption, Diffusion, Pore size distribution
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-240364 (URN)10.1007/s11242-018-1182-3 (DOI)000459472600005 ()2-s2.0-85055973654 (Scopus ID)
Note

QC 20190108

Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2019-03-19Bibliographically approved
Magnusson, J., Hallgren, M., Malm, R. & Ansell, A. (2019). Numerical analyses of shear in concrete structures subjected to distributed blast loads. Engineering structures
Open this publication in new window or tab >>Numerical analyses of shear in concrete structures subjected to distributed blast loads
2019 (English)In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323Article in journal (Refereed) Submitted
Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Dynamic loading, shear failure, numerical modelling, FEM, shear span
National Category
Other Civil Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-250797 (URN)
Note

QC 20190509

Available from: 2019-05-06 Created: 2019-05-06 Last updated: 2019-05-13Bibliographically approved
Gasch, T., Eriksson, D. & Ansell, A. (2019). On the behaviour of con-crete at early-ages: A multiphase description of hygro-thermo-chemo-mechanical properties. Cement and Concrete Research, 116, 202-216
Open this publication in new window or tab >>On the behaviour of con-crete at early-ages: A multiphase description of hygro-thermo-chemo-mechanical properties
2019 (English)In: Cement and Concrete Research, ISSN 0008-8846, E-ISSN 1873-3948, Vol. 116, p. 202-216Article in journal (Refereed) Published
Abstract [en]

Understanding the early-age behaviour of concrete is of importance for designing durable concrete structures. To contribute to the improvement of this, a hygro-thermo-chemo-mechanical model is presented that accounts for phenomena such as hydration, external and internal drying, self-heating, creep, shrinkage and fracture. The model is based on a multiphase porous media framework, using the Thermodynamically Constrained Averaging Theory (TCAT) as starting point to derive the governing equations of the system. This allows for a systematic treatment of the multiscale properties of concrete and how these develop during hydration, e.g. chemical and physical fixation of water. The proposed mathematical model is implemented within the context of the Finite Element Method (FEM), where all physical fields are solved in a fully-coupled manner. Chosen properties of the model are demonstrated and validated using three experimental results from the literature. Generally, the simulated results are in good agreement with the measurements.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Hydration, Microstructure, Creep, Shrinkage, Modeling
National Category
Infrastructure Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-240363 (URN)10.1016/j.cemconres.2018.09.009 (DOI)000457667500023 ()2-s2.0-85057608758 (Scopus ID)
Note

QC 20190109

Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2019-03-15Bibliographically approved
Eriksson, D., Gasch, T., Malm, R. & Ansell, A. (2018). Freezing of partially saturated air-entrained concrete: A multiphase description of the hygro-thermo-mechanical behaviour. International Journal of Solids and Structures, 152-153, 294-304
Open this publication in new window or tab >>Freezing of partially saturated air-entrained concrete: A multiphase description of the hygro-thermo-mechanical behaviour
2018 (English)In: International Journal of Solids and Structures, ISSN 0020-7683, E-ISSN 1879-2146, Vol. 152-153, p. 294-304Article in journal (Refereed) Published
Abstract [en]

Even though air-entrained concrete is usually used for concrete structures located in cold climates that are exposed to wet environments, frost damage is frequently detected during inspections. However, it is often hard to assess the extent and severity of the damage and, thus, there is a need for better tools and aids that can complement already established assessment methods. Several studies have successfully shown that models based on poromechanics and a multiphase approach can be used to describe the freezing behaviour of air-entrained concrete. However, these models are often limited to the scale of the air pore system and, hence, hard to use in applications involving real structures. This study proposes a hygro-thermo-mechanical multiphase model which describes the freezing behaviour of partially saturated air-entrained concrete on the structural scale. The model is implemented in a general FE-code and two numerical examples are presented to validate and show the capabilities of the model. The first concerns a series of experimental tests of air-entrained cement pastes, whereas the second aims to show the capability of the model to account for an initial non-uniform distribution of moisture. While the model predictions underestimate the magnitude of the measured strains, the results still show that the model can capture the general freezing behaviour observed in the experimental tests on the structural scale. Furthermore, the results demonstrate that the model is capable of describing freezing induced deformations caused by non-uniform moisture distributions.

Keywords
Freezing, Partially saturated, Air-entrained concrete, Structural scale, Finite element modelling
National Category
Civil Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-237303 (URN)10.1016/j.ijsolstr.2018.07.004 (DOI)000447576100023 ()2-s2.0-85051402406 (Scopus ID)
Note

QC 20181114

Available from: 2018-10-26 Created: 2018-10-26 Last updated: 2019-01-07Bibliographically approved
Sjölander, A. & Ansell, A. (2018). Investigation of non-linear drying shrinkage for end-restrained shotcrete of varying thickness. Magazine of Concrete Research, 70(6), 271-279
Open this publication in new window or tab >>Investigation of non-linear drying shrinkage for end-restrained shotcrete of varying thickness
2018 (English)In: Magazine of Concrete Research, ISSN 0024-9831, E-ISSN 1751-763X, Vol. 70, no 6, p. 271-279Article in journal (Refereed) Published
Abstract [en]

Tunnels in hard, jointed rock are commonly reinforced with shotcrete (sprayed concrete) applied directly on the irregular rock surface. The thickness for such linings can be as small as 50 mm, which result in a fast drying. The resulting shrinkage of the restrained lining is a well-known phenomenon, which leads to cracking. The installation of drainage systems also results in an end-restrained shotcrete lining that is more prone to shrinkage cracking. The drying process is a complex problem that depends on multiple factors such as cement content, porosity and ambient air conditions (i.e. temperature, relative humidity and wind speed). Two numerical models capable of capturing the structural effects of drying shrinkage were compared in this study. It was found that inclusion of non-linear drying shrinkage is important for accurately describing crack initiation in an end-restrained shotcrete slab. The best fit to the experimental data was obtained when the rate of drying was described as a non-linear decreasing function.

Place, publisher, year, edition, pages
ICE Publishing, 2018
Keywords
cracks & cracking, shrinkage, slabs & plates
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-223781 (URN)10.1680/jmacr.17.00171 (DOI)000425130400001 ()2-s2.0-85042038519 (Scopus ID)
Funder
Rock Engineering Research Foundation (BeFo)
Note

QC 20180307

Available from: 2018-03-07 Created: 2018-03-07 Last updated: 2019-02-13Bibliographically approved
Sjölander, A. & Ansell, A. (2017). Analysis of the interaction between rock and shotcrete for tunnel support. In: Marianne Tange Holst (Ed.), XXIII Nordic Concrete Research Meeting: . Paper presented at Nordic Concrete Research.
Open this publication in new window or tab >>Analysis of the interaction between rock and shotcrete for tunnel support
2017 (English)In: XXIII Nordic Concrete Research Meeting / [ed] Marianne Tange Holst, 2017Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

The first part of a project aiming at increase the knowledge and understanding of how shotcrete (sprayed concrete) in interaction with rock could better be modelled is presented. The study focus on how an irregular thickness of shotcrete will affect its structural capacity. Examples show that continuously bonded shotcrete have an ability to redistribute local stresses while partly de-bonding leads to localized, wide cracks. One goal is to obtain a better understanding for how and why cracking and bond failure is initiated. The results obtained so far are here briefly summarized and commented, also showing some examples of results.

Keywords
Cracking, Fibres, Modelling, Structural Design, Testing.
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-225521 (URN)
Conference
Nordic Concrete Research
Funder
Rock Engineering Research Foundation (BeFo)
Note

QC 20180411

Available from: 2018-04-06 Created: 2018-04-06 Last updated: 2018-04-11Bibliographically approved
Ahmed, L. & Ansell, A. (2017). Dynamic measurements for determination of Poisson’sratio of young concrete. In: : . Paper presented at XXIII Symposium on Nordic Concrete Research & Development. Aalborg
Open this publication in new window or tab >>Dynamic measurements for determination of Poisson’sratio of young concrete
2017 (English)Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
Aalborg: , 2017
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-235276 (URN)
Conference
XXIII Symposium on Nordic Concrete Research & Development
Note

QC 20180920

Available from: 2018-09-19 Created: 2018-09-19 Last updated: 2018-09-20Bibliographically approved
Schönbeck, P., Löfsjögård, M. & Ansell, A. (2017). Requirements on concrete floor structures - a comparison of medical imaging facilities. In: Marianne Tange Holst (Ed.), Proceedings of XXIII Nordic Concrete Research Symposium in Aalborg: . Paper presented at XXIIIth Symposium on Nordic Concrete Research & Developement, 21. – 23. August 2017 in Aalborg, Denmark.
Open this publication in new window or tab >>Requirements on concrete floor structures - a comparison of medical imaging facilities
2017 (English)In: Proceedings of XXIII Nordic Concrete Research Symposium in Aalborg / [ed] Marianne Tange Holst, 2017Conference paper, Published paper (Refereed)
Abstract [en]

Requirements management in construction projects have a tendency towards production-driven processes and definition of technical solutions. The stakeholders are involved by being asked to comment on defined products which can have consequences on the performance of the end-product. This comparison describes three projects within the Stockholm County where the scope to build new medical imaging facilities with the same requirements on the concrete floor structure. The result shows that the same requirements have resulted in different solutions which could have an impact on the performance of the buildings. Further research regarding tools for systematic requirements management is needed to ensure performance and sustainability of new buildings.

Keywords
Execution, Modelling, Structural Design, Sustainability
National Category
Civil Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-217369 (URN)
Conference
XXIIIth Symposium on Nordic Concrete Research & Developement, 21. – 23. August 2017 in Aalborg, Denmark
Funder
Stockholm County Council
Note

QC 20171215

Available from: 2017-12-13 Created: 2017-12-13 Last updated: 2019-04-15Bibliographically approved
Rydell, C., Gasch, T., Eriksson, D. & Ansell, A. (2014). Stresses in water filled concrete pools within nuclear facilities subjected to seismic loads. Nordic Concrete Research (51), 43-62
Open this publication in new window or tab >>Stresses in water filled concrete pools within nuclear facilities subjected to seismic loads
2014 (English)In: Nordic Concrete Research, ISSN 0800-6377, no 51, p. 43-62Article in journal (Refereed) Published
Abstract [en]

This paper presents a study on water filled pools within nuclear facilities subjected to seismic loads. The type of structure studied is an elevated rectangular concrete tank, supported by the reactor containment, which is a high cylindrical concrete structure. Seismic analysis is performed using finite element models, accounting for fluid-structure interaction (FSI) between the water and the concrete structure. The stresses in a concrete pool are calculated, also investigating the changes in stresses as additional cross-walls are added. The effects from earthquakes dominated by low and high frequencies are evaluated, representative for conditions at the West coast of North America and Northern Europe, respectively. It is shown that the coupled fluid-structure systems have more significant modes in the high frequency range compared to the models without water, that is, for frequencies at which the Northern European type earthquake has significant energy compared to the Western North American earthquake. The seismic analyses show that the relative increase of hydrodynamic pressure is higher when the outer walls of the pool are stiffened due to the inclusion of additional cross-walls. With the inclusion of additional cross-walls, modes with lower natural frequencies, although still relatively high, become more important for the hydrodynamic pressure response. Leading to a higher stress response in the outer walls of the pool for models including the additional cross-walls compared to models without cross-walls. The study indicates that the effect from fluid-structure interaction is of great importance also for seismic loads with relatively high-frequency content.

National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-145402 (URN)
Note

QC 20150211. Updated from manuscript to article in journal

Available from: 2014-05-19 Created: 2014-05-19 Last updated: 2018-12-14Bibliographically approved
Eriksson, D., Gasch, T. & Ansell, A.A hygro-thermo-mechanical multiphase model for long-term water absorption into air-entrained concrete.
Open this publication in new window or tab >>A hygro-thermo-mechanical multiphase model for long-term water absorption into air-entrained concrete
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Many concrete structures located in cold climates and in contact with free water are cast with air-entrained concrete. The presence of air pores significantly affects the absorption of water in the concrete, and it might take decades before these are fully saturated. This generally improves the long-term performance of such structures and in particular their frost resistance. To study the long-term moisture conditions in air-entrained concrete, a hygro-thermo-mechanical multiphase model is presented, where the rate of water filling of air pores is described as a separate diffusion process. The driving potential is the concentration of dissolved air, obtained using an averaging procedure with the air pore size distribution as the weighting function. The model is derived using the Thermodynamically Constrained Averaging Theory (TCAT) as a starting point. Two examples are presented to demonstrate the capabilities and performance of the proposed model. These show that the model is capable of describing the complete absorption process of water in air-entrained concrete, and yield results that comply with laboratory and in situ measurements.

Keywords
Air-entrained concrete, Multiphase model, Long-term absorption, Diffusion, Pore size distribution
National Category
Infrastructure Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-225114 (URN)
Note

QC 20180403

Available from: 2018-03-29 Created: 2018-03-29 Last updated: 2018-04-03Bibliographically approved
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