| 1. |
- Oja, Johan, et al.
(författare)
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Mätutrustning för bestämning av fibervinkel och kärnvedsinnehåll vid tvärtransport av träprodukter i råsorteringen
- 2006
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Rapport (refereegranskat)abstract
- The aim of the project has been to integrate technology for measuring fibre angle and heartwood content into an equipment that measures both properties during transverse feed in the green sorting. The results show that technology based on laser and image analysis makes this possible. The project has also proved that it is possible to produce straighter lumber by sorting out the part that is most prone to skewness and put these boards in the bottom of the stack during drying. The results were very clear and when following up the results in the secondary processing, the yield was improved in both cross-cutting and planing. The next step should be to verify that the technology works also on spruce and to study the potential in combining measurement technology with improved drying technology. Key words: Fibre angel, spiral grain, Scots pine, heartwood, drying, skewness
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| 2. |
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| 3. |
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| 4. |
- Björngrim, Niclas, et al.
(författare)
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Factory Mounted and Retrofit Passive Resistance Sensors Adapted to Monitor Moisture Content in Timber Bridges
- 2017
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Ingår i: BioResources. - : North Carolina State University. - 1930-2126 .- 1930-2126. ; 12:4, s. 7218-7227
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Tidskriftsartikel (refereegranskat)abstract
- The biggest threats to the longevity of a timber bridge are rot and decay. Wood protection by design, inspections, and monitoring of the bridge for elevated moisture content will ensure that the full service life of the structure can be achieved. Today's sensors for moisture content measurements are limited in their functionality and range. This paper presents a sensor that can be both factory installed and retrofitted, which can measure the moisture content through the cross-section of the member in a timber bridge. The sensor has been mounted on Sundbron bridge during manufacturing and retrofitted on Gislaved bridge. The ensuing measurements helped to adjust a design flaw on Gislaved bridge. Monitoring of Sundbron showed that the bridge deck dried up after the bridge had been exposed to sleet and snow during the on-site assembly of the stress laminated bridge deck
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| 5. |
- Björngrim, Niclas, 1980-, et al.
(författare)
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The use of large-scale X-ray computed tomography for the evaluation of damaged structural elements from an old timber bridge
- 2022
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Ingår i: Wood Material Science & Engineering. - : Taylor & Francis Group. - 1748-0272 .- 1748-0280. ; 17:6, s. 1028-1029
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Tidskriftsartikel (refereegranskat)abstract
- This paper shows how timber structures in our cultural heritage can be evaluated by large-scale X-ray computed tomography (CT) to supplement visual inspection and conventional strength and biological degradation tests. Approx. 25 year old preservative-impregnated timber beams from a nearly 300-year-old timber bridge were replaced due to severe degradation. The condemned beams were examined by CT scanning, and three-point bending and decay tests were performed. The CT imaging gave a good overview of the internal structure of the beams, and features such as rot, nails and cracking could easily be detected and quantified. The CT images indicate that mild-steel nails from the decking of the bridge were the main cause of subsequent degradation by rot fungus. The load at breakage and the modulus of elasticity (MOE) values of the condemned beams were approx. half those of the undamaged reference beam. Large-scale CT scanning is a powerful tool for the non-destructive inspection of timber members in historical structures.
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| 6. |
- Fjellström, Per-Anders
(författare)
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Fältmätning bjälklag, Lotsen
- 2001
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Trätek har på uppdrag av bl a Norra Massivträ AB utfört långtidsmätningar på ett mellanbjälklag av massivträ i Lotsen, Ursviken. Mätningarnas syfte är att fastställa klimatrelaterade förändringar i konstruktionen. Mätningarna omfattar temperatur/fuktmätning i omgivning, temperatur/fuktmätning i trävirke och spännkraft i fem spännstag.
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| 7. |
- Fjellström, Per-Anders
(författare)
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Fältmätning bjälklag, Prefekten 1
- 2001
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Trätek har på uppdrag av Martinssons Trä AB utfört långtidsmätningar på ett mellanbjälklag av massivträ i Prefekten 1, Skellefteå. Mätningarnas syfte är att fastställa klimatrelaterade förändringar i bjällklaget. Mätningarna omfattar tempertur/fukt i omgivningen, temperatur/fukt i trävirket, och spännkraft i två spännstag. Mätningarna görs fortlöpande och all mätdata lagras för bearbetning och sammanställning halvårsvis.
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| 8. |
- Fjellström, Per-Anders
(författare)
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Fältmätning bjälklag, Prefekten II
- 2001
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Trätek har startat långtidsmätningar på ett mellanbjälklag i Prefekten II, Skellefteå. Mätningarnas syfte är att fastställa klimatrelaterade förändringar i konstruktionen.
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| 9. |
- Fjellström, Per-Anders
(författare)
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Fältmätning gång- och cykelbro, Årjäng
- 2001
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Trätek har startat långtidsmätningar på en gång- och cykelbro över väg 172 i Årjäng. Mätningarnas syfte är att fastställa klimatrelaterade förändringar i brokonstruktionen.
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| 10. |
- Fortino, Stefania, et al.
(författare)
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A multi-Fickian hygro-thermal model for timber bridge elements under Northern Europe climates
- 2016
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Ingår i: WCTE 2016. - 9783903024359 ; , s. 2068-2075
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Konferensbidrag (refereegranskat)abstract
- This work proposes a multi-Fickian method to analyse the hygro-thermal behaviour of timber bridge elements under Northern Europe climates. A temperature-dependent wood hysteresis is included in the model and the thermal effects due to temperatures above and below zero are taken into account. As a case study, the model is used for the hygro-thermal simulation of a glulam beam of Älsvbacka bridge in North of Sweden that was monitored by using wireless sensors in a previous study. The model, implemented in Abaqus FEM code, is able to predict the states of moisture and temperature in protected parts of the beam by using as external loads the relative humidity and temperature of the air provided by in-situ measurements. Furthermore a simplified model using a wood hysteresis independent of temperature is found to provide similar results and appears easier to implement in finite element codes.
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| 11. |
- Niklewski, Jonas, et al.
(författare)
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Durability of rain-exposed timber bridge joints and components
- 2016
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Ingår i: WCTE 2016. - 9783903024359 ; , s. 4667-4675
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Konferensbidrag (refereegranskat)abstract
- The design of details is an important aspect in durability design of rain-exposed timber structures. Joints are considered the weak-points of these structures as they accumulate moisture and facilitate deterioration by decay. The present study aims to study the influence of detail design, and its effect on the service life, by estimating the decay rate in a number of rain-exposed timber components and joints, typically found in timber bridges. A test-setup was exposed outdoors over a period of one year while the moisture content was measured in specific measuring points. The test-setup included groups of beams, columns and joints commonly found in timberbridges. For the beams and columns, the effectiveness of typical protective measures was also tested. The annual decay rate was estimated using two different decay prediction models. Compared to a reference beam, the results show that structural protection reduced the risk of decay while joints and end-grain tended to be at increased risk. The lowest service life, estimated to 3-4 years, was found close to end-grain where drying was hindered but moisture could accumulate. In general, the discrepancy between the two decay models was large for low to medium exposure and decreased with increasing exposure.
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| 12. |
- Pousette, Anna, et al.
(författare)
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Broinspektion - träbroar
- 2004
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Rapport (refereegranskat)abstract
- Many modern timber bridges have been built in Sweden during the last ten years. This report is about Swedish timber bridges and methods for the inspection of the bridges. It also includes reports from some inspections of timber bridges. The relatively new timber bridges are in good condition. The most frequent problems and corrective actions regarding the bridges have been related to railings, surface treatments and connections. At close inspections of some timber bridges no serious damages were found that will reduce the performance during the next ten years. Timber bridge design has been improved throughout the years, and some of the defects found depended on shortcomings in details in the early bridges. Several bridges were not sufficiently maintained. Periodic cleaning is important for keeping the wood clean and dry to ensure a long life of the bridges. Defects of the inspected bridges were mainly related to cracks and delaminations, surface treatments, moisture contents, steel coatings, connections, pre-stressed steel bars, connections to abutments and pavings. The principally used field measuring method is the resistive moisture meter, as moisture is the most critical parameter for the decay of wood. The resistive moisture meter has good accuracy and is almost non-destructive, as the electrodes only cause small holes in the wood. Rot on the outside of beams can be found with a knife and on the inside with a drill. Less destructive methods for rot surveys are the Pilodyn for outer rot and Resistograph for inner rot, but they sometimes give measures that can be hard to interpret as wood is an inhomogeneous material with large natural variations. Key words: timber bridge, inspection, wood moisture meter, Pilodyn, Resisiograph
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| 13. |
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| 15. |
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| 16. |
- Pousette, Anna, et al.
(författare)
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Inspektion av träbroar
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport innehåller anvisningar för inspektion av träbroar. Rapporten är en svensk bearbetning av rapporten "Inspection of Timber Bridges" från Nordic Wood-projektet "Broar av trä". I Sverige har under de senaste 10 åren byggts nästan 500 nya träbroar. Rapporten har tagits fram för att ge inspekörer av träbroar ett stöd, samt kännedom om vilka hjälpmedel som finns till hands vid inspektion av träbroar. I rapporten har inte tagits ställning till hur ofta en inspektion av en träbro bör utföras, eller hur omfattande den bör vara.
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| 17. |
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