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Hellgren, R. & Malm, R. (2024). Systematic Literature Search and Meta Regression of Measured Static Ice Loads on Concrete Dams. Journal of cold regions engineering, 38(2), Article ID 04024002.
Open this publication in new window or tab >>Systematic Literature Search and Meta Regression of Measured Static Ice Loads on Concrete Dams
2024 (English)In: Journal of cold regions engineering, ISSN 0887-381X, E-ISSN 1943-5495, Vol. 38, no 2, article id 04024002Article in journal (Refereed) Published
Abstract [en]

This study presents a systematic literature review of ice load measurements on dams. Several hypotheses about the relationship between the maximum ice load and external variables are tested using regression analysis on the data collected from the literature. The performed tests show that ice thickness, water level change category, and dam height are factors that have a significant and relevant relationship with the magnitude of all measured ice loads. The ice thickness is the only tested variable that also shows a significant and relevant relationship with differences in ice load between winters at one dam. The variation in recorded ice load from several sensor positions at one dam during the same winter is considerable. Generally, the difference between the sensor area and the structure–ice interaction area is large, resulting in extensive extrapolation and uncertainties regarding the representativeness of the measured results.

Place, publisher, year, edition, pages
American Society of Civil Engineers (ASCE), 2024
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-343198 (URN)10.1061/JCRGEI.CRENG-661 (DOI)2-s2.0-85183457603 (Scopus ID)
Note

QC 20240208

Available from: 2024-02-08 Created: 2024-02-08 Last updated: 2024-02-08Bibliographically approved
Enzell, J., Nordström, E., Sjölander, A., Ansell, A. & Malm, R. (2023). Physical Model Tests of Concrete Buttress Dams with Failure Imposed by Hydrostatic Water Pressure. Water, 15(20), Article ID 3627.
Open this publication in new window or tab >>Physical Model Tests of Concrete Buttress Dams with Failure Imposed by Hydrostatic Water Pressure
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2023 (English)In: Water, E-ISSN 2073-4441, Vol. 15, no 20, article id 3627Article in journal (Refereed) Published
Abstract [en]

Although the failure of a concrete dam is a complex and highly dynamic process, the current safety assessments of concrete gravity and buttress dams rely on a simplified 2D stability analysis, which neglects the load redistribution due to 3D monolith interactions and the valley shape. In addition, the estimation of breach parameters in concrete dams is based on assumptions rather than analyses, and better prediction methods are needed. Model tests have been conducted to increase the understanding of the failure behavior of concrete dams. A scale model buttress dam, with a scale of 1:15, consisting of 5 monoliths that were 1.2 m in height and 4 m in width, was constructed and loaded to failure using water pressure. The model dam had detachable abutment supports and shear keys to permit variations in the 3D behavior. The results showed that the shear transfer was large between the monoliths and that the failure of a single dam monolith is unlikely. A greater lateral restraint gives not only a higher failure load but also a better indication of impending failure. These findings suggest that the entire dam, including its boundary conditions, should be considered during a stability assessment. The results also suggest that the common assumption in dam safety codes that a single monolith fails during flooding analysis is not conservative. The dataset obtained provides a foundation for the future development of dam-monitoring alarm limits and for predictive models of dam-breaching processes.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
concrete dams; buttress dams; physical model tests; dam failures; stability assessment
National Category
Infrastructure Engineering
Research subject
Civil and Architectural Engineering, Concrete Structures
Identifiers
urn:nbn:se:kth:diva-334840 (URN)10.3390/w15203627 (DOI)001095503200001 ()2-s2.0-85175366976 (Scopus ID)
Note

QC 20231017

Available from: 2023-08-28 Created: 2023-08-28 Last updated: 2023-11-30Bibliographically approved
Hellgren, R., Enzell, J., Ansell, A., Nordström, E. & Malm, R. (2022). Estimating the Ice Loads on Concrete Dams Based on Their Structural Response. Water, 14(4), Article ID 597.
Open this publication in new window or tab >>Estimating the Ice Loads on Concrete Dams Based on Their Structural Response
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2022 (English)In: Water, E-ISSN 2073-4441, Vol. 14, no 4, article id 597Article in journal (Refereed) Published
Abstract [en]

In the assessment of concrete dams in cold climate, it is common that the theoretical stability becomes insufficient for load cases that include ice loads. However, the magnitude and return period of these ice loads have a high degree of uncertainty. This study estimates the magnitude of ice loads on eight concrete dam monoliths using measurements of their displacement from 29 winters. In the displacement signals, events are identified and assumed to be caused solely by ice loads. The observed displacement during an event is interpreted as an ice load using a load-displacement relationship derived from FE simulations of each dam. These simulations show that ice loads of the magnitudes given in design guidelines and recorded in previous measurements would significantly affect the structural response of the studied dams. However, only small traces of ice loads can be found in the observed responses of the studied dams. The estimated ice loads are significantly lower than the ice loads recorded in traditional ice load measurements. These results indicate that the average magnitude of ice load on an entire monolith is significantly lower than the measured local pressures. This would imply that ice loads may be a smaller concern regarding dam safety than previously believed.

Place, publisher, year, edition, pages
MDPI AG, 2022
Keywords
ice loads, concrete dams, back-calculation, dam safety, monitoring
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-310035 (URN)10.3390/w14040597 (DOI)000762527900001 ()2-s2.0-85124989768 (Scopus ID)
Note

QC 20220318

Available from: 2022-03-18 Created: 2022-03-18 Last updated: 2023-08-28Bibliographically approved
Enzell, J., Malm, R. & Abbasiverki, R. (2022). Implementation of endurance time analysis for seismic push-over analysis of a concrete gravity dam. In: : . Paper presented at XXIV Nordic Concrete Research Symposium, August 16-19, 2022, Stockholm..
Open this publication in new window or tab >>Implementation of endurance time analysis for seismic push-over analysis of a concrete gravity dam
2022 (English)Conference paper, Published paper (Refereed)
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-320080 (URN)
Conference
XXIV Nordic Concrete Research Symposium, August 16-19, 2022, Stockholm.
Note

QC 20221025

Available from: 2022-10-13 Created: 2022-10-13 Last updated: 2022-11-28Bibliographically approved
Enzell, J., Malm, R. & Tollsten, M. (2022). Predicting the Influence of Seasonal Thermally Induced Cracking on a Reinforced Concrete Arch Dam. KSCE Journal of Civil Engineering
Open this publication in new window or tab >>Predicting the Influence of Seasonal Thermally Induced Cracking on a Reinforced Concrete Arch Dam
2022 (English)In: KSCE Journal of Civil Engineering, ISSN 1226-7988, E-ISSN 1976-3808Article in journal (Refereed) Published
Abstract [en]

Many of the world’s concrete dams are approaching the end of their expected service life and many of these dams are cracked due to environmental effects. It is thus desirable to be able to extend the service life of many of these dams. It is therefore important to develop reliable methods of analysis to assess the current status of these dams and to determine the safety of these, partly damaged structures. A slender reinforced concrete arch dam is used as a case study with the aim of predicting the structural response, the cracks found in-situ and of assessing the safety of the dam. This dam has cracked extensively along the downstream face primarily due to seasonal temperature variations. A detailed finite element model has been developed to simulate the history of the dam with the variations in ambient conditions that have occurred over its lifetime. The results show good agreement regarding both the crack pattern and displacement of the dam. A procedure to simulate a progressive dam failure, starting from the current state, is utilized to assess the current level of safety. The results show that the cracking has a limited effect on the safety factor of the dam. 

Place, publisher, year, edition, pages
Springer Nature, 2022
National Category
Infrastructure Engineering
Research subject
Civil and Architectural Engineering, Concrete Structures
Identifiers
urn:nbn:se:kth:diva-310464 (URN)10.1007/s12205-022-0112-7 (DOI)000777062300004 ()2-s2.0-85127589767 (Scopus ID)
Note

QC 20220420

Available from: 2022-04-04 Created: 2022-04-04 Last updated: 2022-06-25Bibliographically approved
Magnusson, J., Ansell, A., Hallgren, M. & Malm, R. (2022). Shear in concrete structural elements subjected to dynamic loads. In: : . Paper presented at XXIV Nordic Research Symposium, August 16-19, 2022, Stockholm..
Open this publication in new window or tab >>Shear in concrete structural elements subjected to dynamic loads
2022 (English)Conference paper, Published paper (Refereed)
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-320079 (URN)
Conference
XXIV Nordic Research Symposium, August 16-19, 2022, Stockholm.
Note

QC 20221018

Available from: 2022-10-13 Created: 2022-10-13 Last updated: 2022-10-18Bibliographically approved
Ansell, A. & Malm, R. (2021). Balkar, ramar snittstorheter och fackverk: Exempel och sammanfattning. Stockholm
Open this publication in new window or tab >>Balkar, ramar snittstorheter och fackverk: Exempel och sammanfattning
2021 (Swedish)Report (Other academic)
Place, publisher, year, edition, pages
Stockholm: , 2021. p. 135
Series
TRITA-ABE-RPT ; 2131
National Category
Engineering and Technology
Research subject
Civil and Architectural Engineering, Concrete Structures
Identifiers
urn:nbn:se:kth:diva-304262 (URN)
Note

QC 20211101

Available from: 2021-10-29 Created: 2021-10-29 Last updated: 2022-06-25Bibliographically approved
Hassanzadeh, M., Malm, R. & Hansson, H. (2021). Explosionslasters inverkan på reaktorinneslutningens betongdelar. Stockholm: Strålsäkerhetsmyndigheten (SSM)
Open this publication in new window or tab >>Explosionslasters inverkan på reaktorinneslutningens betongdelar
2021 (Swedish)Report (Refereed)
Place, publisher, year, edition, pages
Stockholm: Strålsäkerhetsmyndigheten (SSM), 2021. p. 101
Series
SSM report ; 2021:22
National Category
Infrastructure Engineering
Research subject
Civil and Architectural Engineering, Concrete Structures
Identifiers
urn:nbn:se:kth:diva-302789 (URN)
Note

QC 20211102

Available from: 2021-10-01 Created: 2021-10-01 Last updated: 2022-06-25Bibliographically approved
Eriksson, D., Wahlbom, D., Malm, R. & Fridh, K. (2021). Hygro-thermo-mechanical modeling of partially saturated air-entrained concrete containing dissolved salt and exposed to freeze-thaw cycles. Cement and Concrete Research, 141, Article ID 106314.
Open this publication in new window or tab >>Hygro-thermo-mechanical modeling of partially saturated air-entrained concrete containing dissolved salt and exposed to freeze-thaw cycles
2021 (English)In: Cement and Concrete Research, ISSN 0008-8846, E-ISSN 1873-3948, Vol. 141, article id 106314Article in journal (Refereed) Published
Abstract [en]

In cold regions, understanding the freeze-thaw behavior of air-entrained concrete is important for designing durable structures and assessing the remaining service life of existing structures. This study presents a hygro-thermo-mechanical multiphase model that describes the cyclic freeze-thaw behavior of partially saturated air-entrained concrete containing dissolved salt. An equilibrium and a non-equilibrium approach are adopted to model the ice formation, including the freeze-thaw hysteresis, inside the porous network. The model also considers the diffusive and convective transport of the dissolved salt coupled to the freeze-thaw processes. Two examples are presented to verify and highlight the capabilities of the model. The first example shows that the model is capable of reproducing the experimentally observed mechanical response of specimens containing NaC1-solutions of different concentrations. In the second example, a larger absorption of liquid from an external reservoir is obtained with an increasing salt concentration in the reservoir, which is consistent with experimental observations.

Place, publisher, year, edition, pages
Elsevier BV, 2021
Keywords
Freezing and thawing (C), Finite element analysis (C), Absorption, Hysteresis, Salt
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-289880 (URN)10.1016/j.cemconres.2020.106314 (DOI)000608764100002 ()2-s2.0-85097753874 (Scopus ID)
Note

QC 20210212

Available from: 2021-02-12 Created: 2021-02-12 Last updated: 2022-06-25Bibliographically approved
Hellgren, R., Petrich, C., Arntsen, B. & Malm, R. (2021). Ice load measurements on Rätan concrete dam using different sensor types. Cold Regions Science and Technology, 103425-103425, Article ID 103425.
Open this publication in new window or tab >>Ice load measurements on Rätan concrete dam using different sensor types
2021 (English)In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, p. 103425-103425, article id 103425Article in journal (Refereed) Published
Abstract [en]

Concrete dams in cold regions are designed to withstand loads from the ice sheet on top of the reservoir. However, the ice load's magnitude and return period are among the most considerable uncertainties in safety assessments of concrete dams. In a previous study, the development and installation of a 1 × 3 m2 prototype ice load panel attached at the upstream face of a concrete dam was presented. The panel is large enough for the ice sheet's cross-section to remain in contact with the panel as the water level varies, and it measures the total ice load without interpolation. This paper presents measurement results from the load panel from winters 2018–19 and 2019–20, an update to the measurement design, and additional ice pressure measurements with traditional stress cells. The panel measured seasonal maximum ice loads of 100 and 200 kN/m for the two winters, respectively. Winter 2019–20, when the panel measured the largest loads, was mild for the location, with great ice thickness near the dam face (1.2 m) and an almost snow-free ice sheet throughout the winter. Two 2.75 × 1.75 m2 dummy panels were installed adjacent to the load panel prior to the winter 2019–20 to minimize the load panel's protruding effect. These panels significantly reduced the local impact, as evident by the crack-pattern of the ice sheet near the load panel. The load panel recorded large ice loads (>75 kN/m) for all combinations with increasing/decreasing air temperature and/or water level. Identification of temperature change events and water level change events during the winters, shows that a change in air temperature, water level, or any combination of these, is not sufficient alone to explain large ice loads at Rätan dam. These findings suggest that other conditions must be satisfied before a water level or temperature change results in large ice loads. In February 2020, three panels consisting of a steel frame with four stress cells on each were placed on the dummy panels’ upstream face, and one single stress cell was placed 6 m out in the reservoir in front of the load panel. The majority of the stress cells recorded ice pressure larger than their measurement range. At the end of the ice season, only two of the panels’ twelve stress cells were still functional, and the ice vastly deformed the steel frames. From the period before the frames were damaged and unrelated to the choice of interpolation method, the recordings by the three stress cell panels at the dam are among the historically largest inferred ice loads on dams.

Keywords
Ice load, Concrete dam, Load panel, Stress cells, Ice pressure. Ice thickness
National Category
Civil Engineering
Research subject
Civil and Architectural Engineering, Concrete Structures
Identifiers
urn:nbn:se:kth:diva-303904 (URN)10.1016/j.coldregions.2021.103425 (DOI)000721725100002 ()2-s2.0-85117401515 (Scopus ID)
Note

QC 20211206

Available from: 2021-10-21 Created: 2021-10-21 Last updated: 2022-06-25Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-3586-8988

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