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- Bergström, Markus, et al.
(författare)
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Structural health monitoring of degrading concrete beams in a laboratory environment
- 2006
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Ingår i: Composites in Civil Engineering. - : International Institute for FRP in Construction (IIFC). ; , s. 335-338
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Much effort has been invested separately on degradation, repair and upgrading of concrete structures. However, few holistic studies including laboratory testing have been performed on the entire cycle during a structures life. Reinforced concrete is the most widely used building material in the world. Normally the life of concrete structures is very long. However, concrete structures possess one drawback; at least in severe environments, the steel reinforcement may corrode. The effects can clearly be seen when the steel reinforcement is attacked by chlorides. The reduced steel cross-section area and loss of bond strength between steel and concrete will lead to increased deformations, cracking and premature ultimate load, thus affecting both the serviceability limit state (SLS) and the ultimate limit state (ULS). Procedures to repair and upgrade the damaged structure are used to increase the structural performance. They follow the structural member of time, a SHM (Structural Health Monitoring) approach is adapted to this project. By applying SHM to a degrading structure it assures that it will keep up to current standards by continuous monitoring, analysing, evaluation and eventually also retrofitting.
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- Plos, Mario, 1963, et al.
(författare)
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Structural assessment of concrete bridges
- 2008
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Ingår i: Nordic Concrete Research. - 0800-6377. ; 38:2008/2, s. 89-101
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Tidskriftsartikel (refereegranskat)abstract
- The paper summarises the work on concrete bridges performed in the EU project Sustainable Bridges. The work provides enhanced assessment methods that are able to prove higher load-carrying capacities and longer fatigue lives for existing concrete railway bridges, and is implemented in a Guideline [1]. Methods for determination of in-situ material properties and advanced methods for structural analysis were developed. One main focus was non-linear analysis, since these provides the greatest potential for discovering of additional sources for load-carrying capacity. Furthermore, methods to assess the remaining structural resistance of deteriorated concrete bridges with respect to corrosion and fatigue were developed.
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- Al-Emrani, Mohammad, 1967, et al.
(författare)
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You have full text access to this content Experimentelle Untersuchung des Ermüdungsverhaltens genieteter Träger
- 2002
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Ingår i: Stahlbau. - 1437-1049 .- 0038-9145. ; :2, s. 145-150
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Tidskriftsartikel (refereegranskat)abstract
- The results from ten fatigue tests performed on six full-scale riveted stringers are presented and discussed. The stringers were taken from a 100 year old bridge, and the tests were performed at two different stress ranges: 60 and ~100 MPa. The tested stringers showed an excellent fatigue performance and their fatigue lives were in correspondence with or above the fatigue design curve given by the codes. Furthermore, the efficiency of using stop-holes to retard fatigue crack propagation in riveted girders was examined. The method was found to be an effective measure when aimed at temporarily arrest the crack propagation in riveted girders.
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- Fransson, Lennart, et al.
(författare)
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Ice loads for wind-power foundations in the Gulf of Bothnia
- 2009
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Ingår i: Proceedings of the 20th International Conference on Port and Ocean Engineering under Arctic Conditions. ; June 9-12, 2009, s. 12-19
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Konferensbidrag (refereegranskat)abstract
- Ice loads measured on lighthouses in the Gulf of Bothnia can serve as guidance for design of foundations for wind-power generators. At some locations in the sea these structures must withstand high pressure from solid land fast ice as well as from ridges or other compacted ice masses that are drifting. Recommendations for design of offshore foundations around the Swedish coastline have recently been written by the authors. For the purpose of design, effective pressure as well as compressive strength is assumed to be independent of ice thickness. All structures should be designed for dynamic ice loads that are dependent on the natural frequency of the structure and the ice drift velocity. Increased effective pressure has earlier been indicated for high speed ice crushing both in field studies and compression tests. The presented results from ice load measurements on lighthouse Norströmsgrund support the suspicion that also design ice loads should increase with drift speed. This rate effect and other uncertainties about the worst case scenario for ice-induced vibrations suggest a more conservative design of wind-power foundations inside the dynamic ice zone.
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- Jonsson, Thomas, et al.
(författare)
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Crash Prediction Models for Intersections on Rural Multilane Highways: Differences by Collision Type
- 2007
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Ingår i: Proceedings of the 86th Annual meeting of TRB, CD-ROM. - : SAGE Publications. ; 2019, s. 91-98
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Konferensbidrag (refereegranskat)abstract
- Accident prediction models are often used to predict the number of accidents on segments and at intersections in the road network. Most often the models are developed for a total number of crashes for the facility, or crashes by severity. However, the frequency and severity of crashes of different types can be expected to vary with regards to the underlying phenomena that cause them to occur. To better account for this variation, this paper describes modeling of accidents at intersections on rural four-lane highways in California separately for four different collision types: Opposite direction crashes, Same direction crashes, Intersecting direction crashes and Single vehicle crashes. The findings from this modeling are reported with a special focus on the differences among crash types with regards to: 1) severity distribution, 2) the dependence on traffic flow, and 3) which variables are best at explaining between site variations in the occurrence of different crash types. There are evident differences in severity as well as the relationship of flow among several of the crash types. Intersecting and Opposite direction crashes are more severe than Same direction crashes. Same and Opposite direction crashes exhibit similar relationships with traffic flow, but there are differences compared to Intersecting direction crashes as well as to Single vehicle crashes. Also the variables that turn out as good predictor variables differ somewhat for each crash type.
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