| 1. |
- Gottsäter, Erik, et al.
(författare)
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Measurements and simulation of temperature in a portal frame bridge
- 2018
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Ingår i: IABSE Symposium, Nantes 2018: Tomorrow's Megastructures. - 9783857481611 ; , s. S24-9-S24-16
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Konferensbidrag (refereegranskat)abstract
- Since thermal loads can cause cracking, they are important to consider in bridge design. In order to evaluate and develop thermal load cases based on real simulations, models for simulating temperatures can be used. In this paper, a model for thermal simulation is used to simulate temperature in a portal frame bridge outside Lund, Sweden. The results are compared with temperature measurements in 13 locations in the same bridge, which were made during a 12-month period. The results show that although many important material parameters were unknown, the model could recreate both daily and seasonal temperature variations, although it tended to render temperatures about 1°C lower than the measurements, at least during summer. The model can be used in future work in determining thermal load values for the specific bridge type, assuming the model uncertainty is considered by e.g. adding 1°C to calculated load values.
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| 2. |
- Gottsäter, Erik, et al.
(författare)
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Validation of Temperature Simulations in a Portal Frame Bridge
- 2018
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Ingår i: Structures. - : Elsevier BV. - 2352-0124. ; 15, s. 341-348
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Tidskriftsartikel (refereegranskat)abstract
- In the design of bridges, thermal loads are important to take into account since they can cause cracking if the structure or structural part is restrained from changing its size. Accurate thermal load values must therefore be used in bridge design, based on knowledge of the actual temperature distribution in the bridge. This paper presents the validation of a model for temperature simulation, to be used in future work in the determination of temperature differences between deck and abutments in portal frame bridges. The validation is performed by comparing simulated temperatures with temperatures measured at 13 locations in a portal frame bridge during a period of 12 months. The simulation model uses measured air temperature, wind speed and long- and short wave radiation as input to calculate the temperature for every hour in the time period, and includes the soil beside the bridge. The results show that the model was capable of predicting the temperature distribution adequately, and that conservative values of the temperature difference between the structural parts can be obtained by adding no more than a ΔT of 1.5 °C to the simulated temperature difference, depending on the application.
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| 3. |
- Honfi, Daniel, et al.
(författare)
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Inspection and monitoring of bridges in Sweden
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report provides an overview about recent research activities and current practice concerning inspection and monitoring of the structural performance of bridges and the related decision-making process. A brief review of common methods of collecting information on structural performance of bridges is presented, followed by a description of the use of the information collected in structural analysis and maintenance planning. An overview about the state of the art is given including recent scientific developments. Finally, the current Swedish practice for bridge management is presented.
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| 4. |
- Kurkinen, Eva-Lotta, et al.
(författare)
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Kriterier för resurssnålt byggande i praktiken
- 2018. - 18
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This work includes monitoring of set criteria for low climate impact from concrete in procurement of concrete structures for brf. Viva in Gothenburg. The criteria were followed up by updating the LCA study performed during the program phase with new data for the completed building, plus a selection of the project stakeholders were also interviewed to gain an insight into how the industry received the set criteria. The work also includes a final sectionregarding the sensitivity of the calculations as well as the uncertainties/error margins and how they can be treated.Buildings that are supposed to last for 100 years will be exposed to climate change, and consequently, parallel to the LCA follow-up, energy simulations were made to see how thermal comfort and heating needs change over time.The results of the LCA follow-up and the set criteria indicate that the requirements were fulfilled for both the prefabricated concrete and the site-cast concrete. Comparing the overall climate impact between the program phase and the procured building was shown not to be possible since the construction has changed too much, for example, the heated surface area has increased by about 50%, while more materials have been used in walls and floor joints, amongst other things. A sensitivity analysis has instead been carried out showing that the contracted construction has 30% lower climate impact per BOA compared to if it was built with traditional concrete. Had the original construction details from the program stage been used for walls and floor joints, the climate impact would have been about 40% lower instead.Therefore, in future requirements, consideration should also be given to the structures and the amount of materials used, and not just to the concrete recipe as is in this case.The climate simulations show that there is probably a large number of unrecorded cases of low energy apartments that have elevated indoor temperatures in summer even in today's climate.
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| 5. |
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| 6. |
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| 7. |
- Larsson Ivanov, Oskar, et al.
(författare)
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Uncertainty and variation in LCA - Implementation of probabilistic methods to assess environmental impacts of infrastructures
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- For most applications trying to interpret the real world uncertainties will be an important factor to consider, which is also true for Life-Cycle Assessment used for estimating total environmental impact during the life-cycle of products, services, buildings, structures, roads etc. The construction and usage of infrastructure are major causes of emissions and energy use, thus making it even more important for society to aim at reducing this impact. One way of reducing environmental impact is by using LCA to show improvements for specific items and/or benefits of using a specific solution over another. To be able to use LCA, or any other calculated estimation, for comparisons it is of great importance to incorporate effects of uncertainties and to understand where such uncertainties have their sources. Otherwise, any attempt on comparing two solutions will be flawed and there is a risk for bias towards a specific solution. The aim of the work presented in this report have been to describe and discuss the types of uncertainties present in a LCA, and to discuss their importance, source and influence. An extensive review of the current state of the art of both uncertainties in general and specifically for LCA have been performed to find the most common ways of including uncertainties in LCA, with focus on the possibilities and limitations of different types of methods. It was found that many previous attempts on including uncertainties in LCA exists, and they showed that it is now possible to using probabilistic methods such as Monte Carlo simulations to incorporate uncertainties in LCA-tools, since the computational capacity have increased. The common problem for all previous studies and the study presented here is the availability of validated input data including uncertainty estimations. Initiatives exist for data quality control; however, they do not fully consider the effect of uncertainties, and typically have been limited to the consideration of variations in emission factors only. Other factors such as system boundaries and choices made by the user have a much larger influence on the result than a small variation in the emission factor itself.To evaluate this, the basis for a methodology considering uncertainties in LCA and possibilities for controlling these uncertainties is presented. The methodology is based on general definitions of uncertainties to be able to understand the source and characteristics of each affecting parameter and for making informed decisions on how to reduce the uncertainty depending on the purpose of the LCA. This kind of methodology will especially be valuable for raising awareness of uncertainties in LCA for different stages of the building process.The possibility of including uncertainties in a LCA-tool for infrastructures in also presented, showing possibilities for studying the sensitivity of the input parameters and the propagation of uncertainties. A case study is used to demonstrate these possibilities, showing the importance of considering uncertainties in all input parameters. It is shown that the influence of other factors apart from the emission factors can be large, such as material amounts and expected service life, and that they have to be considered if reasonable results are sought. It should be noted, however, that the case study presented in this report serves illustrative purposes and includes significant simplifications.
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| 8. |
- Leander, John, et al.
(författare)
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A decision support framework for fatigue assessment of steel bridges
- 2018
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Ingår i: Engineering Failure Analysis. - : Elsevier BV. - 1350-6307 .- 1873-1961. ; 91, s. 306-314
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Tidskriftsartikel (refereegranskat)abstract
- Many bridges are approaching or have already passed their expected service life. For steel bridges, fatigue is often the decisive degradation phenomenon that theoretically puts restrictions on a continued use. At the same time, fatigue is also afflicted with large uncertainties on the resistance side as well as on the action effect side. An accurate assessment of the service life will require measures outside the governing regulations but understanding what steps to take and how to consider the outcome for decisions on interventions can be a difficult task for a non-expert. This paper presents possible assessment actions and a decision support framework for rational decisions on interventions to extend the theoretical service life of existing bridges. A case study of a critical railway bridge is incorporated to demonstrate the framework. The aim is to provide a tool for bridge managers on how to evaluate and procure different assessment actions.
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| 9. |
- Nasr, Amro, et al.
(författare)
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Climate change impact on safety and performance of existing and future bridges
- 2018
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Ingår i: Proceedings of the Sixth International Symposium on Life-Cycle Civil Engineering (IALCCE 2018). ; , s. 1735-1741, s. 1735-1741
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Konferensbidrag (refereegranskat)abstract
- Recent decades have seen an increased attention towards the threat of climate change to our built environment and not least our infrastructure. Accounting for the different ways in which potential climate change scenarios can affect our infrastructure is paramount in determining appropriate adaptation and risk management strategies. This paper presents the initial findings of a new research project which is concerned with establishing an improved management of the risks to our infrastructure, especially bridges, in light of a changing climate. In this paper, a preliminary survey of the climate change related risks on bridges is conducted. Timely consideration of these impacts is of utmost importance to ensure a satisfactory performance of our bridges in the future. The interplay between the different risks and how the occurrence of one risk may influence other risks is also briefly discussed. The future stages of the project are mentioned as well. The authors would like to acknowledge the support of the Swedish Transport Administration. Any opinions, findings, or conclusions in this work are those of the authors and are not necessarily in accordance with those of the Swedish Transport Administration.
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