| 1. |
- Sundell, Jonas, 1984, et al.
(författare)
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Economic valuation of hydrogeological information when managing groundwater drawdown
- 2019
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Ingår i: Hydrogeology Journal. - : Springer Science and Business Media LLC. - 1431-2174 .- 1435-0157. ; 27:4, s. 1111-1130
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Tidskriftsartikel (refereegranskat)abstract
- © 2019, The Author(s). A procedure is presented for valuation of information analysis (VOIA) to determine the need for additional information when assessing the effect of several design alternatives to manage future disturbances in hydrogeological systems. When planning for groundwater extraction and drawdown in areas where risks—such as land subsidence, wells running dry and drainage of streams and wetlands—are present, the need for risk-reducing safety measures must be carefully evaluated and managed. The heterogeneity of the subsurface calls for an assessment of trade-offs between the benefits of additional information to reduce the risk of erroneous decisions and the cost of collecting this information. A method is suggested that combines existing procedures for inverse probabilistic groundwater modelling with a novel method for VOIA. The method results in (1) a prior analysis where uncertainties regarding the efficiency of safety measures are estimated, and (2) a pre-posterior analysis, where the benefits of expected uncertainty reduction deriving from additional information are compared with the costs for obtaining this information. In comparison with existing approaches for VOIA, the method can assess multiple design alternatives, use hydrogeological parameters as proxies for failure, and produce spatially distributed VOIA maps. The method is demonstrated for a case study of a planned tunnel in Stockholm, Sweden, where additional investigations produce a low number of benefits as a result of low failure rates for the studied alternatives and a cause-effect chain where the resulting failure probability is more dependent on interactions within the whole system rather than on specific features.
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| 2. |
- Sundell, Jonas, 1984, et al.
(författare)
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Comprehensive risk assessment of groundwater drawdown induced subsidence
- 2019
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Ingår i: Stochastic Environmental Research and Risk Assessment. - : Springer Science and Business Media LLC. - 1436-3240 .- 1436-3259. ; 33:2, s. 427-449
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Tidskriftsartikel (refereegranskat)abstract
- © 2019, The Author(s). We present a method for risk assessment of groundwater drawdown induced land subsidence when planning for sub-surface infrastructure. Since groundwater drawdown and related subsidence can occur at large distances from the points of inflow, the large spatial extent often implies heterogeneous geological conditions that cannot be described in complete detail. This calls for estimation of uncertainties in all components of the cause-effect chain with probabilistic methods. In this study, we couple four probabilistic methods into a comprehensive model for economic risk quantification: a geostatistical soil-stratification model, an inverse calibrated groundwater model, an elasto-plastic subsidence model, and a model describing the resulting damages and costs on individual buildings and constructions. Groundwater head measurements, hydraulic tests, statistical analyses of stratification and soil properties and an inventory of buildings are inputs to the models. In the coupled method, different design alternatives for risk reduction measures are evaluated. Integration of probabilities and damage costs result in an economic risk estimate for each alternative. Compared with the risk for a reference alternative, the best prior alternative is identified as the alternative with the highest expected net benefit. The results include spatial probabilistic risk estimates for each alternative where areas with significant risk are distinguished from low-risk areas. The efficiency and usefulness of this modelling approach as a tool for communication to stakeholders, decision support for prioritization of risk reducing measures, and identification of the need for further investigations and monitoring are demonstrated with a case study of a planned railway tunnel in Varberg, Sweden.
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| 3. |
- Rempling, Rasmus, 1976, et al.
(författare)
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Utmattning
- 2021
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Ingår i: Betonghandbok material - Hårdnad betong, fysikaliska egenskaper och beständighet. - 9789179170882 ; , s. 485-510
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Mathern, Alexandre, 1986, et al.
(författare)
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Concrete Support Structures for Offshore Wind Turbines: Current Status, Challenges, and Future Trends
- 2021
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 14:7
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Forskningsöversikt (refereegranskat)abstract
- Today’s offshore wind turbine support structures market is largely dominated by steel structures, since steel monopiles account for the vast majority of installations in the last decade and new types of multi-leg steel structures have been developed in recent years. However, as wind turbines become bigger, and potential sites for offshore wind farms are located in ever deeper waters and ever further from the shore, the conditions for the design, transport, and installation of support structures are changing. In light of these facts, this paper identifies and categorizes the challenges and future trends related to the use of concrete for support structures of future offshore wind projects. To do so, recent advances and technologies still under development for both bottom-fixed and floating concrete support structures have been reviewed. It was found that these new developments meet the challenges associated with the use of concrete support structures, as they will allow the production costs to be lowered and transport and installation to be facilitated. New technologies for concrete support structures used at medium and great water depths are also being developed and are expected to become more common in future offshore wind installations. Therefore, the new developments identified in this paper show the likelihood of an increase in the use of concrete support structures in future offshore wind farms. These developments also indicate that the complexity of future support structures will increase due to the development of hybrid structures combining steel and concrete. These evolutions call for new knowledge and technical know-how in order to allow reliable structures to be built and risk-free offshore installation to be executed.
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| 5. |
- Dymitrow, Mirek, et al.
(författare)
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Crossing dichotomies and breaking mental patterns: Green business development when all else fails?
- 2017
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Ingår i: 8th International Scientific Conference “Rural Development 2017: Bioeconomy Challenges”, 23–24 November, 2017 Kaunas, Lithuania.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Obtaining sustainable and inclusive societal organization is not merely a simple matter of ‘doing it’ by subscribing to some winning formula. Given that conceptual frameworks always guide our thoughts, judgments and actions (Latour, 2013; Harvey, 1996; Dennett, 1993), the ways in which we relate to concepts chosen to serve as guiding forces for future development will eventually determine its outcome. As scholarly evidence continuously suggests the concepts ‘rural’ and ‘urban’ are increasingly recognized as artificial barriers for conducting sound and integrated development endeavors in a globalized reality of interconnectedness. In line with the Sustainable Development Goals, which aim to eradicate poverty, shield the planet and safeguard prosperity for all, commitment to universal access to healthy food year round has become an important agenda point. This, however, has been exacerbated by binary thinking and separate ways of doing policy. This paper aims to share experiences from a unique project launched in the northern parts of Gothenburg, Sweden’s second largest city. While the area offers ample resources and immense opportunities for areal economies, it at the same time remains one of Gothenburg’s most segregated, with high levels of unemployment, ill health and crime. The uniqueness of the project lies not only in its way of abridging the rural-urban divide, but also by consciously deferring from the debilitating rhetoric of previous ‘immigrant policies’, and instead focusing on agricultural productivity, small-scale food producers and sustainable food strategies. Such exhortations to bridge between philosophical and material polarities, however, have not come without conceptual and practical challenges, something this paper aims to subsume and open up to debate.
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| 6. |
- Rempling, Rasmus, 1976, et al.
(författare)
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Performance requirements for Swedish transport infrastructure - A pre-study of challenges and possibilities
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In recent years, significant worldwide research has been conducted regarding the performance assessment of bridges and the concept of performance indicator has been introduced However, there are still significant discrepancies in how these indicators are obtained and used. Simultaneously, it is desirable to achieve processes and methods that are direct, i.e. that measured values are directly compared with projected values over time. This project concerns methods for verification of technical performance requirements. The feasibility study brought together interdisciplinary researchers, consultants, and entrepreneurs to gather knowledge, anchor the research agenda, and implement performance requirements. The project concludes that there is a need for a “Holistic multi-parameter verification/validation system” that relies on the knowledge gained in structural health monitoring research.
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| 7. |
- Mathern, Alexandre, 1986
(författare)
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Addressing the complexity of sustainability-driven structural design: Computational design, optimization, and decision making
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Being one of the sectors with the largest environmental burden and high socio-economic impacts sets high requirements on the construction industry. At the same time, this provides the sector with great opportunities to contribute to the globally pursued sustainability transition. To cope with the increasing need for infrastructure and, at the same time, limit their sustainability impacts, changes and innovation in the construction sector are required. The greatest possibility to limit the sustainability impact of construction works is at the early design phase of construction projects, as many of the choices influencing sustainability are made at that point. Traditionally, an early choice of a preferred design is often made based on limited knowledge and past experience, considering only a handful of options. This preferred design is then taken on to the successive stages in the stepwise design process, leading to suboptimization. Alternatively, many different design choices could be considered and evaluated in a more holistic approach in order to find the most sustainable design for a particular application. However, finding design solutions that offer the best sustainability performance and fulfil all structural, performance and buildability requirements, require methods that allow considering different design options, analysing them, and assessing their sustainability. The aim of this thesis is to explore and develop methods enabling structural engineers to take sustainability objectives into account in the design of structures. Throughout this thesis, a number of methods have been explored to take sustainability aspects into account in the structural design process. As a first step, highly parameterized computer codes for sustainability-driven design have been developed. These codes interoperate with FE analysis software to automatically model and analyse design concepts over the whole design space and verify compliance with structural design standards. The codes were complemented with a harmonized method for life cycle sustainability performance assessment, in line with the state-of-the-art standards. Here, sustainability criteria were defined covering environmental, social, economic, buildability and structural performance for multi-criteria assessment of design concepts. To identify the most sustainable designs within the set, multi-objective optimization algorithms were used. Algorithms that address the high expense of constraint function evaluations of structural design problems were developed and integrated in the parameterized computer codes for sustainability-driven design. To ensure the applicability and validity of these methods, case studies based on real-world projects and common structural engineering problems were used in this thesis. Case studies for bridges and wind turbine foundations as well as a benchmark case of a reinforced concrete beam were investigated. The case studies highlight the potential of the methods explored to support the design of more sustainable structures, as well as the applicability of the methods in structural engineering practice. It is concluded that it is possible and beneficial to combine computational design, life cycle sustainability assessment, and multi-objective design optimization as a basis for decision making in the design phase of civil engineering projects. A wide adoption of such a sustainability-driven design optimization approach in structural engineering practice can directly improve the sustainability of the construction sector.
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| 8. |
- Desivyana, Nindya, 1997, et al.
(författare)
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Challenges in the adoption of sustainable criteria in the Swedish property development industry
- 2023
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Ingår i: Procedia Computer Science. - : Elsevier BV. - 1877-0509. ; 219, s. 1752-1759
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Konferensbidrag (refereegranskat)abstract
- The construction industry is facing an increased focus on sustainability and climate neutrality, causing property developers to implement new requirements into the procurement documents, which are also driven by the national agenda. This study explores the current state of sustainability practice among Swedish property developers and identifies the main obstacles to expand further the implementation of the sustainability criteria. How the property developers define and implement sustainability requirements has been assessed through qualitative semi-structured interviews, focusing on sustainability certification systems, Life Cycle Assessment (LCA), and social sustainability. The results show usage of sustainability certification systems for marketing purposes and high awareness and practice of LCA, even though the accuracy of LCA was questioned. This study also identified guideline gaps for circular economy and social sustainability measurements, which could relate to low initiatives from the certification systems.
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| 9. |
- van Eldert, Jeroen, 1987-, et al.
(författare)
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Application of Measurement While Drilling Technology to Predict Rock Mass Quality and Rock Support for Tunnelling
- 2020
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Ingår i: Rock Mechanics and Rock Engineering. - : Springer. - 0723-2632 .- 1434-453X. ; 53:3, s. 1349-1358
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Tidskriftsartikel (refereegranskat)abstract
- A tunnelling project is normally initiated with a site investigation to determine the in situ rock mass conditions and to generate the basis for the tunnel design and rock support. However, since site investigations often are based on limited information (surface mapping, geophysical profiles, few bore holes, etc.), the estimation of the rock mass conditions may contain inaccuracies, resulting in underestimating the required rock support. The study hypothesised that these inaccuracies could be reduced using Measurement While Drilling (MWD) technology to assist in the decision-making process. A case study of two tunnels in the Stockholm bypass found the rock mass quality was severely overestimated by the site investigation; more than 45% of the investigated sections had a lower rock mass quality than expected. MWD data were recorded in 25 m grout holes and 6 m blast holes. The MWD data were normalised so that the long grout holes with larger hole diameters and the shorter blast holes with smaller hole diameters gave similar results. With normalised MWD data, it was possible to mimic the tunnel contour mapping; results showed good correlation with mapped Q-value and installed rock support. MWD technology can improve the accuracy of forecasting the rock mass ahead of the face. It can bridge the information gap between the early, somewhat uncertain geotechnical site investigation and the geological mapping done after excavation to optimise rock support.
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| 10. |
- Petersson, Jesper, 1974
(författare)
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Blurring the shoreline: De- and re-infrastructuring and the changing colors of European flood policy
- 2021
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Ingår i: Environment and Planning E: Nature and Space. - : SAGE Publications. - 2514-8494 .- 2514-8494 .- 2514-8486. ; 4:2, s. 623-644
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Tidskriftsartikel (refereegranskat)abstract
- This paper provides a genealogy of the emergence of a common EU flood policy, including the scope and direction of this policy. Noticing how EU policy proposes green infrastructure (associated with using nature as a buffer zone in managing floods) as an alternative to grey infrastructure (implying fixed installations of concrete and cement), this paper adopts the theoretical lens of the so-called infrastructural turn, which advocates a relational investigation of infrastructure. By engaging this approach, the paper shows how flood infrastructure can contain very different compositions of (unruly) water and (settled) land. A narrative of a historically strong focus on guarding society from the powerful forces of nature through a fixed line of defense is increasingly giving way to more muddy states—quite literally—where society is expected to learn to live with flooding and show ecological consideration. To capture the EU’s, and especially the European Commission’s efforts to establish a pan-European flood infrastructure that accommodates this turn, the concepts of de- and re-infrastructuring are developed. These concepts act as heuristic devices to capture how policy performs some combinations between water and land as constituting an attractive and functional flood infrastructure, but constitutes other infrastructural relations of the aquatic and the terrestrial as undesirable and, hence, as malfunctioning. This performative act of distinguishing between what constitutes “good and proper” versus “bad and undesirable” infrastructure is referred to as a politics of infrastructure.
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| 11. |
- Kharazmi, Parastou, 1977-
(författare)
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Experimental evaluation of a rubber-epoxy polymeric system used in the rehabilitation of sewer infrastructure- Dataset
- 2019
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Annan publikationabstract
- This dataset includes data related to water sorption analyses to support research findings stated in the article:"Experimental evaluation of a rubber-epoxy polymeric system used in the rehabilitation of sewer infrastructure: a case study in Sweden" with the following abstract: One rehabilitation method used mainly for wastewater sewers in residential buildings involves applying a rubber-epoxy composite to the inner surface of the aged pipeline. In order to understand the material’s performance and stability in operation, during which it is constantly exposed to deteriorative factors, the properties of the material were studied in the laboratory under artificial water and air aging conditions. Changes in the material were monitored by means of tests such as thermal analyses, mechanical testing and water absorption assessment.
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| 12. |
- Rempling, Rasmus, 1976, et al.
(författare)
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Research Roadmap - Information Integration in Construction
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This Roadmap is developed for a challenging Global environment where fundamental paradigms such as data generation and analysis, are shifting at a seismic rate, while change in Construction Industries across the Globe is, in the main, confined to large-scale projects and slow. Against this background, the authors set out to also give a ‘voice’ to small-to-medium scale projects through which the construction output Worldwide is delivered. Hence, project scale was one of the key considerations throughout this Roadmap. Moreover, the authors conceptualized data integration by taking the realities of doing business’ in construction into consideration. The emergent framework facilitates the discussion of knowledge and data integration at organisational, team, operational and technical levels across key project phases. This approach recognizes that business is done through projects but change can only come about if appropriate organizational structures and processes are put in place. Last, but not least, the authors strived to ensure that data integration was not considered solely from a technical perspective. Organisational, team and individual aspects of data integration were integrated in the research framework. Through our work the individual’s willingness to collaborate emerged as a critical driver for high levels of integration, while our survey did identify “Reluctance to work across professional boundaries” as a major barrier to integration. Hence, we conclude that research on integration should pay due attention to the individual.
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| 13. |
- Ståhle, Alexander, et al.
(författare)
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Designguide för Smarta gator
- 2022
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Designguiden för smarta gator konkretiserar hur de fyra megatrenderna urbanisering, digitalisering, samhällsförändringar och miljöförändringar leder till nya krav och utformningsprinciper för framtidens gator. Guiden är tänkt att fungera som en inspiration och ett underlag för att förnya svensk gatupolicy på nationell, regional och kommunal nivå.Guiden innehåller utöver en inledning följande kapitel: en historisk tillbakablick (gatans utveckling), gatans användning, gatans delar, gatans design, designprocessen, guidens genomförande.
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| 14. |
- Blomfors, Mattias, 1990, et al.
(författare)
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Partial safety factors for the anchorage capacity of corroded reinforcement bars in concrete
- 2019
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Ingår i: Engineering structures. - : Elsevier BV. - 0141-0296 .- 1873-7323. ; 181, s. 579-588
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Tidskriftsartikel (refereegranskat)abstract
- Many reinforced concrete bridges in Europe and around the world are damaged by reinforcement corrosion and the annual maintenance costs are enormous. It is therefore important to develop reliable methods to assess the structural capacity of corroded reinforced concrete structures and avoid unnecessary maintenance costs. Although there are advanced models for determining the load carrying capacity of structures, it is not obvious how they should be used to verify the performance of existing structures. To confidently assess the bond of corroded reinforcement in concrete, for example, the calculation model must give a sufficient safety margin. When designing new structures, semi-probabilistic approaches (such as the partial safety factor method) are adopted to achieve the target reliabilities specified in structural design codes. This paper uses probabilistic methods to develop partial factors for application in an existing bond model, to assess the safety of corroded reinforced concrete structures. The response of the bond model was studied using Monte Carlo (MC) simulations for several design cases, with probability distributions fitted to the results. Partial factors were then derived, based on these distributions. Furthermore, an MC-based simulation technique called “importance sampling” was used to study the reliability of several deterministic bond assessments conducted using these partial factors. The results show that deterministic assessments which use the proposed partial factors lead to a safety level at least equal to the target value. The results presented in this paper will support the assessment of reinforced concrete structures with anchorage problems and give a reasonable approximation of the anchorage capacity with sufficient safety margin. When generalised to cover other failure modes and structural configurations, this will enable better utilisation of damaged structures and lead to major environmental and economical savings for society.
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| 15. |
- Abbas, Nada, et al.
(författare)
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Information Needs of Gravel Road Stakeholders
- 2022
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Ingår i: Infrastructures. - : MDPI. - 2412-3811. ; 7:12
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Tidskriftsartikel (refereegranskat)abstract
- Within any ecosystem, information sharing is essential. In this paper, the Swedish gravel road ecosystem is studied, where information plays a crucial role for the effective management of operations and maintenance. However, efficient information sharing is not enabled due to the lack of appropriate information systems. For addressing this issue, this paper intends to elicit information needs of gravel road stakeholders to support the design of a cloud-based information system. The main purpose is to explore the information needs of stakeholders within the Swedish gravel road ecosystem. Data were collected through in-depth semi-structured interviews with 11 participants representing key stakeholders in the ecosystem. Template analysis was used for analyzing the interview results. The major findings were a set of information needs covering road identification and condition, weather conditions, accessibility and traffic, maintenance policy, and sensor data. The results form a comprehensive information model for the further development of a cloud-based gravel road management system that would contribute to increased traffic safety and comfort, lower maintenance and management costs, and better decision-making abilities.
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| 16. |
- Mathern, Alexandre, 1986, et al.
(författare)
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Practical metamodel‑assisted multi‑objective design optimization for improved sustainability and buildability of wind turbine foundations
- 2022
-
Ingår i: Structural and Multidisciplinary Optimization. - : Springer Science and Business Media LLC. - 1615-1488 .- 1615-147X. ; 65:2
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we study the potential of using kriging metamodelling to perform multi-objective structural design optimization using finite element analysis software and design standards while keeping the computational efforts low. A method is proposed, which includes sustainability and buildability objectives, and it is applied to a case study of reinforced concrete foundations for wind turbines based on data from a large Swedish wind farm project. Sensitivity analyses are conducted to investigate the influence of the penalty factor applied to unfeasible solutions and the size of the initial sample generated by Latin hypercube sampling. A multi-objective optimization is then performed to obtain the optimum designs for different weight combinations for the four objectives considered. Results show that the kriging-obtained designs from samples of 20 designs outperform the best designs in the samples of 1000 designs. The optimum designs obtained by the proposed method have a sustainability impact 8–15% lower than the designs developed by traditional methods.
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| 17. |
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| 18. |
- Adl-Zarrabi, Bijan, 1959, et al.
(författare)
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Safe and Sustainable Coastal Highway Route E39
- 2016
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Ingår i: Transportation Research Procedia. - : Elsevier BV. - 2352-1465 .- 2352-1457. ; 14, s. 3350-3359
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Konferensbidrag (refereegranskat)abstract
- The project “Coastal Highway Route E39” have a mandate to, investigate how infrastructure can exploit renewable energy to reduce environmental footprint. Three PhD projects were initiated on this subject at Chalmers University of Technology by Norwegian public road administration. Results in this paper conclude that (1) Life Cycle Assessment should have a geographical dimension with respect to assumptions and input data, (2) there are substantial potential to reduce the CO2 emissions from the E39, especially when considering an electrification, and (3) the harvested energy from hydronic pavement system can be enough for maintaining ice-free roads in Nordic countries.
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| 19. |
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| 20. |
- Gschösser, Florian, et al.
(författare)
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Hidden Ecological Potentials in the Production of Materials for Swiss Road Pavements
- 2012
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Ingår i: Journal of Management in Engineering - ASCE. - 0742-597X. ; 27:1, s. 13-21
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Tidskriftsartikel (refereegranskat)abstract
- Sustainability has become a major concern in the field of civil infrastructures in recent years. Developing road construction projects with lower ecological impacts over a project’s entire life cycle can help in making road infrastructure contribute to sustainable development. This study focuses on the ecological potentials in the production of road materials used in Swiss road pavements. The environmental assessment was performed using a cradle-to-gate life-cycle assessment (LCA) approach in which all processes from the raw material extraction to the finished product were considered. The comparison of the results of the best-case asphalt pavement and the standard asphalt pavement for Swiss highway construction shows ecological potentials of up to 55%. Use of the best-case concrete pavement lowers the environmental impact by up to 53% in comparison to the worst-case concrete pavement for Swiss highways. Concerning composite pavements, the best-case variant offers an ecological potential 38% higher than the standard pavement.
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| 21. |
- Jönsson, Håkan, et al.
(författare)
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Återvinn fler näringsämnen än fosfor i avloppsvatten
- 2012
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Ingår i: Dagens nyheter. - 1101-2447. ; ?, s. 6-
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Annan publikation (populärvet., debatt m.m.)abstract
- För att minska utsläppen av växthusgaser bör vi återvinna fler växtnäringsämnen ur avloppsslammet. Regeringens ensidiga fokus på fosfor i detta avseende riskerar att skada det långsiktiga miljöarbetet. Vi vill skärpa miljömålen och inkludera även ämnen som kväve, kalium och svavel, skriver professorer och forskare från SLU.
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| 22. |
- Mathern, Alexandre, 1986, et al.
(författare)
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Experimental study of time-dependent properties of a low-pH concrete for deposition tunnels
- 2018
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Ingår i: fib Symposium. - 2617-4820. ; , s. 1726-1735
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Konferensbidrag (refereegranskat)abstract
- The Swedish Nuclear Fuel and Waste Management Company developed a method for the final disposal of canisters for spent nuclear fuel in tunnels at depths of about 500 meters. The concept for closure of the deposition tunnels is based on a bentonite seal supported by a spherical concrete dome structure. In order to fulfil the requirements specific to the repository concept, a special mix of low-pH self-compacting concrete was developed. A series of large-scale castings and laboratory tests were conducted to gain experience on this low-pH concrete mix, in conjunction with the full-scale demonstration test of an unreinforced concrete dome plug in the underground hard rock laboratory in Äspö, Sweden. The laboratory tests aimed at studying the creep properties under high sustained compressive stresses of the low-pH concrete mix, its shrinkage properties and the properties of the rock-concrete interface. This paper provides an overview of these tests and analyses the latest results of the recently completed creep tests, which include 6 years of measurements. These results allow to improve understanding of the structural behaviour of the concrete plug and to assess the effects of the very high pressure acting on the plug on its deformations, cracking and water tightness.
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| 23. |
- Bagherbandi, Mohammad, Professor, et al.
(författare)
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Time transfer and significance of vertical land motion in relativistic geodesy applications: a review paper
- 2023
-
Ingår i: Frontiers in Earth Science. - : Frontiers. - 2296-6463. ; 11
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Forskningsöversikt (refereegranskat)abstract
- Determination of the Earth’s gravity field and geopotential value is one of the fundamental topics in physical geodesy. Traditional terrestrial gravity and precise leveling measurements can be used to determine the geopotential values at a local or regional scale. However, recent developments in optical atomic clocks have not only rapidly improved fundamental science but also contributed to applied research. The latest generation of optical clocks is approaching the accuracy level of 10−18 when facilitating atomic clock networks. These systems allow examining fundamental theories and many research applications, such as atomic clocks applications in relativistic geodesy, to precisely determine the Earth’s gravity field parameters (e.g., geopotential values). According to the theory of relativistic geodesy, the frequency difference measured by an optical clock network is related to the gravity potential anomaly, provided that the effects of disturbing signals (i.e., tidal and non-tidal contributions) are filtered out. The relativistic geodesy principle could be used for a practical realization of global geodetic infrastructure, most importantly, a vertical datum unification or realization of height systems. This paper aims to review the background of relativistic (clock-based) geodesy and study the variations of optical atomic clock measurements (e.g., due to hydrology loading and land motion).
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| 24. |
- Hörteborn, Axel, 1986
(författare)
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Ship Behaviour and Ship Bridge Allision Analysis
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The demand for maritime transport has increased with the growing demand for worldwide trade. This has led to a major increase in maritime traffic and ship sizes over the last decades, which raises the probability of accidents. The methods used in maritime risk assessments today are based on old hypotheses that do not include all data available today. The main objective of this thesis is to develop numerical models and methods for the analysis of what is considered as normal navigation behaviour at sea today and improve the analysis of probability for ship-bridge allisions. The first part of the thesis describes what is considered as normal meeting distance at sea today. This information is later used while identifying failure events to ensure that the event behaviour was not caused by other ships. These few cases are excluded from the methodology since the communication and situational awareness in the situations are not known. However, while studying the probability of ship-bridge accidents, it is also important to understand how waterway restrictions may affect the probability of ship-ship collisions. Therefore, this thesis also includes a study of how the improved knowledge concerning meeting distance could be used in a near ship-ship collision identification model. One of the main findings considering normal meeting distance is that small and large ships meet each other at a similar distance at sea. In the second part of the thesis, a methodology is proposed to estimate the probability of ship-bridge allision. The presented methodology uses Automatic Identification System (AIS) data and a ship manoeuvring simulator to simulate and analyse marine traffic with regards to risks for accidents, such as ship-bridge allisions. A failure event identification method is also presented, which is needed to determine the frequency, duration and behaviour for the accident scenarios. The three events that were modelled and simulated in the simulator were: drifting ship, sharp turning ship and missing turning point. The probability of the different failure events corresponded to previous statistics confirming the AIS-based methodology. This means the methods to obtain the probability and duration of the failure events could be utilised in other areas. The simulation methodology was confirmed with the probability of grounding in the Great Belt VTS area. This thesis firstly contributes to a better understanding of the modelling of probability for ship-bridge allisions. This will support bridge-building engineers who need to take into account accidental loads from ship-bridge allision while designing bridges. Secondly, this thesis also contributes to a better representation of normal behaviour at sea, which is used both in fairway designs and in estimations of ship-ship collisions.
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| 25. |
- Adam, Abderisak, 1988, et al.
(författare)
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How task heterogeneity and frequency relates to knowledge codification: Evaluating the Shared Construction Guidelines (SCG) of 24 Swedish Public Client Organizations
- 2017
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Ingår i: 9th Nordic Conference on Construction Economics and Organization. ; , s. 1-9
-
Konferensbidrag (refereegranskat)abstract
- Over a sustained period of time, organizational theorists have argued that public sector organizationsare more inefficient than their private counterparts. Recent studies have explained these inefficienciesas the result of having to do with capabilities rather than resources thereby calling for an improvementof the capabilities of public organizations. A key mechanism for achieving such improvements is thearticulation and codification of knowledge. This study examines an attempt at codifying knowledge inthe form of a set of shared construction guidelines (SCG) employed by 24 large public clientorganizations in the Municipality of Gothenburg, Sweden. Specifically, these guidelines are viewedwith respect to the framework of Zollo and Winter (2002) in terms of how organizations with high taskheterogeneity and low task frequency can more effectively develop dynamic capabilities through thedeliberate learning mechanism of knowledge codification. Preliminary results indicate that taskfrequency and organizational size are stronger indicators than heterogeneity in deciding whether apublic client organization utilizes knowledge codification systems such as the SCG.
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| 26. |
- Adam, Abderisak, 1988
(författare)
-
Managing construction challenges: Viability of a dynamic capabilities approach for the public client
- 2016
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Construction clients in the public sector face a large number of challenges in designing, procuring and managing construction projects in a manner that is conducive to the organization’s overall goals. In particular, clients have faced challenges in delivering projects that satisfied the projects’ goals with respect to cost overruns, delays and sustainable construction. The role of the client in managing these challenges has more recently been emphasized with a growing number of studies and governmental reports calling for the development of the client’s capabilities.This thesis examines the capabilities of the construction client through a dynamic capabilities framework, particularly with respect to the activities of sensing, seizing and transforming. Furthermore, the thesis explores whether the concept of dynamic capabilities is a viable approach for understanding how to manage the clients’ capabilities in a way that ensures that construction-related challenges are addressed. The thesis is based primarily on a case study of a large public construction client located in Sweden.Findings are presented in three appended papers. The thesis concludes with a discussion on the viability of using a dynamic capabilities framework in the specific case described in this thesis. It is argued that the concept of dynamic capabilities is inadequate for capturing the specific context in which public client organizations operate. Suggestions for alternative approaches to understanding the management and development of capabilities are then discussed.
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| 27. |
- Aygül, Mustafa, 1970, et al.
(författare)
-
A comparative study of different fatigue failure assessments of welded bridge details
- 2013
-
Ingår i: International Journal of Fatigue. - : Elsevier BV. - 0142-1123. ; 49:0, s. 62-72
-
Tidskriftsartikel (refereegranskat)abstract
- Five different welded joints frequently used in steel bridges have been selected to investigate the accuracy and applicability of three fatigue assessment methods. The first method, also categorised as the global method, is the nominal stress method, while the more advanced methods are the hot spot and the effective notch stress methods. Solid element based finite element models for welded bridge details were created by following the modelling requirements of each fatigue assessment method. A statistical evaluation based on the results of the finite element analyses and the fatigue test data collected from the literature was performed to determine the mean and characteristic fatigue strength. In addition, the standard deviation for each data series was also determined to conclude how well each method describes the fatigue strength of each welded detail. A method with a lower standard deviation is regarded as more accurate. Moreover, the evaluated results from each method were compared with the recommended fatigue strength values in the Eurocode 3 (EN 1993-1-9:2005) and IIW codes. In the light of the test results in this study, it appears that the codes are in reasonable agreement with the test data, even though a few examples of the opposite occurred. The conclusion based on the revised results in this article indicates that the nominal stress method yields satisfactory results, despite its simplicity. When considering the effort involved in creating FE models for numerical analysis, it seems clear that the choice of the nominal method is fairly acceptable.
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| 28. |
- Blomfors, Martin, et al.
(författare)
-
Reliability analysis of corroded reinforced concrete beam with regards to anchorage failure
- 2019
-
Ingår i: Life-Cycle Analysis and Assessment in Civil Engineering. - : CRC Press/Balkema. - 9781138626331 - 9781351857574 ; , s. 337-344, s. 337-344
-
Konferensbidrag (refereegranskat)abstract
- Reinforcement corrosion is a common problem in reinforced concrete infrastructure today, and it is expected to increase in the future. To simply replace the corroded structures with new ones requires large resources, both in financial and environmental terms. Therefore it is important that existing structures are used to their full potential, also after the onset of corrosion. This paper presents a reliability study of the anchorage capacity of a reinforced concrete beam including reinforcement corrosion. The sensitivity of the different input parameters is also studied. As expected, the results show that the reliability is reduced with corrosion; the magnitude depends to a large extent on the modelling uncertainty used for the bond model for corroded reinforcement. The sensitivity analysis shows an influence of corrosion also on the sensitivities of the input parameters, which is expected based on the properties of the underlying bond model. This paper demonstrates that probabilistic evaluations give valuable insight of the reliability, which can be used to prolong the service-life of existing infrastructure and save both money and the environment.
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| 29. |
- Mathern, Alexandre, 1986, et al.
(författare)
-
Lessons learned from the construction, inspection, and defect assessment of reinforced concrete foundations for wind turbines
- 2022
-
Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 12:3
-
Tidskriftsartikel (refereegranskat)abstract
- Foundations of wind turbines are subject to challenging conditions during their service life as they support ever larger wind turbines under complex loading situations. There have been numerous reports of cracked concrete foundations of wind turbines. Cracking can impair the durability and serviceability of the foundations, thereby leading to very expensive repairs or even to premature failure of the structure. To avoid cracking-related problems and improve the quality of concrete foundations, it is important to gather information and experience from the production stage and its outcome. However, although problems and defects in the construction of wind turbine foundations are widespread, they have very seldom been documented and reported, in particular from a contractor’s perspective. This article analyses and critically reviews data collected during the production, inspection, diagnosis, and repair activities conducted in relation to the construction of foundations for a wind farm project in Sweden. The extent of defects observed on individual foundations is assessed and used to investigate the eventual relation between the observed deviations and different production aspects. Investigation methods to determine the importance of these defects and their consequences and possible remediation measures are also discussed. Finally, recommendations are proposed to improve the quality control of wind turbine foundations.
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| 30. |
- Tegos, Ioannis, et al.
(författare)
-
Experimental and analytical research on the influence of the shear span ratio on the maximum shear strength of hollow circular R/C cross sections
- 2013
-
Ingår i: fib Symposium TEL-AVIV 2013: Engineering a Concrete Future: Technology, Modeling and Construction, Proceedings. - 9789659203901 ; , s. 369-372
-
Konferensbidrag (refereegranskat)abstract
- This paper investigates a particular problem encountered in the design of reinforced concrete elements of circular hollow cross sections. Such problems still appear to be unclear, due to the fact that the current codes deal, al most exclusively, with the design of rectangular cross sections and no specific provisions are given for other cross sections. Hence, the design of such members is being dealt with either poor methods or with the use of methods that normally apply to rectangular cross sections. Specifically, the research deals with the influence of the shear span ratio on the maximum shear strength of reinforced concrete members with circular hollow cross sections. Six reinforced concrete specimens having a circular hollow cross section have been tested. lt was attempted to verify the accuracy of the proposed analytica(model, which estimates the shear strength for circular hollow R/C cross sections. The study was mainly focused on the shear span ratio, which is the dominant factor in the design of structural elements under shear loading. It is useful to be noted that R/C elements of thin hollow circular cross section are used in the case of bridge piers.
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| 31. |
- Täljsten, Björn, 1961-, et al.
(författare)
-
Assessment of prestressed concrete bridges - challenges
- 2020
-
Ingår i: IABSE Symposium, Wroclaw 2020. - Zürich : International Association For Bridge And Structural Engineering (IABSE). ; , s. 487-494
-
Konferensbidrag (refereegranskat)abstract
- Prestressed concrete bridges are important parts of our infrastructure. They are susceptible to different kinds of deterioration processes. Examples of damages and deficiencies are cracking, corrosion, voids, bond loss, reduction of cover layer, delamination, fatigue and loss of stiffness and strength. This necessitates methods to continuously assess their condition in order to avoid problems that might lead to shorter service life or reduction of structural integrity. Many of the existing prestressed bridges in Europe are now approaching their design life length. However, with proper and continuous inspection, monitoring and assessment, we may plan proactive maintenance and the structural safety can be assured or – if necessary - increased. This will save both money and decrease the environmental impact of the structure.
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| 32. |
- Williams Portal, Natalie, 1986, et al.
(författare)
-
Bending behaviour of novel Textile Reinforced Concrete-foamed concrete (TRC-FC) sandwich elements
- 2017
-
Ingår i: Composite Structures. - : Elsevier BV. - 0263-8223 .- 1879-1085. ; 177, s. 104-118
-
Tidskriftsartikel (refereegranskat)abstract
- A novel sandwich element design consisting of two facings made of carbon reinforced Textile Reinforced Concrete (TRC), a low density foamed concrete (FC) core and glass fibre reinforced polymer (GFRP) connecting devices was experimentally investigated according to quasi-static and cyclic quasi-static four-point bending. Optical measurements based on Digital Image Correlation (DIC) were taken during testing to enable a detailed analysis of the bending behaviour and level of composite action. A model, verified by the experiments, was developed based on non-linear finite element analysis (NLFEA) to gain further insight on the failure mechanisms. Under both loading conditions, the bending behaviour of the TRC-FC composite elements was characterized by favourable load bearing capacity, partial composite action, superior ductility and multiple fine cracking. The connecting devices were found to be the critical elements causing the initial failure mechanism in the form of localized pull-out within an element.
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| 33. |
- Berghauser Pont, Meta, 1972, et al.
(författare)
-
Förtätning av stationsnära områden för god tillgänglighet. Utveckling av en analys - och utvärderingsmetod
- 2022
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Det finns en vilja att förtäta i närheten av stationer för att öka användningen av kollektivtrafik och därmed minska klimatpåverkan kopplad till transpor- ter. Förtätning bidrar bland annat till att skapa levande stationssamhällen, med blandade funktioner, god tillgäng- lighet och miljöer som är trygga och vistelsevänliga där olika grupper och behov möts. Potentialerna är många men så även utmaningarna. Förtätning av stationsnära områden kan också leda till oönskade konsekven- ser för social, ekonomisk och ekologisk hållbarhet. Den här rap- porten kan förhoppningsvis ge ökad förståelse för förtätning i relation till regional tillgänglighet samt för positiva och negativa konsekvenser av förtätning i stationsnära områden. Den kan också skapa insikter om hur olika alternativ för utveckling av stations- nära områden kan värderas utifrån Agenda 2030, särskilt Mål 11: Hållbara städer och samhällen. Rapporten är framtagen inom projektet Urbana stationssamhäll- en – förtätning av stationsnära områden för god tillgänglighet (2020–2022) som finansierats av Trafikverket och bedrivits i sam- verkan mellan Urban Futures vid GMV (projektägare), Arkitektur och samhällsbyggnadsteknik vid Chalmers tekniska högskola, Gö- teborgsregionen (GR), Samhällsplanering vid Högskolan Dalarna och Samhällsplanering och miljö vid KTH.
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| 34. |
- Stojanovski, Todor
(författare)
-
Urban Mobility Certificates (UMCs) : Informing mobility choices, carbon emissionsand energy use from transportation
- 2020
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Urban transportation today consumes scarce resources of fossil fuels and it is a majorcause for environmental damage and accelerating climate change. To achieve sustainablemobility in the cities, it is necessary to improve energy efficiency and lower carbonemissions through the promotion of walking, cycling and especially public transportation.The urban form is a great obstacle in achieving sustainable mobility. Many Swedishcities were designed for the private automobile and they lack possibilities to walk, cycle anduse public transportation. To address this problem, this project developed and testedUrban Mobility Certificates (UMCs) or transportdeklaration in Swedish. The UMCsvisually inform sustainable mobility as integration with walking, cycling and publictransportation, estimate modal shares, transportation energy use in kWh/year/person andcarbon emission in t CO2/year/person. Visualizing this information has a potential totrigger a virtuous cycle of transforming neighborhoods, catalyzing sustainabledevelopment to better integrate walking, cycling and public transportation in Swedishneighborhoods.The UMCs produce reasonable results with acceptable errors that are common for thiskind of trip generation models. The can be used to identify unsustainable mobility inexisting neighborhoods and new developments. The UMCs directly inform sustainablemobility in a very concise form (integration, modal shares, transportation energy use inkWh/year/person and carbon emission in t CO2/year/person) and show a complex set ofurban form and accessibility factors as background for the modal shares forecasts. Bothconcise and complex information is needed to illuminate the complex link between urbanform and sustainable mobility. In addition, the methodology can be used to analyzealternative scenarios to redesign sprawling Swedish neighborhoods into more sustainableurban forms. Scenarios like mixed development, introduction of public transportation orcreating a network of walkable streets (called promenadstad in Swedish) can decreasetransportation energy use by 1000 kWh/year/person to 3000 kWh/year/person(extensions of historical urban centers) or halve the Swedish average of 6000kWh/year/person. It is very important to use the UMCs in the earliest stage of the urbanplanning and development process.Sustainable mobility is possible only if there are choices to walk, cycle and use publictransportation. To help in redesigning and redeveloping the Swedish neighborhoods thatare oriented to the automobile, this project furthermore presented a model of small andlarge Swedish city with typical neighborhoods. The application of the UMCs in Swedishplanning and development processes must be understood as a process of informing aboutlack of mobility choices and urban interventions such as introduction of walkable streets,cycling and public transportation infrastructures, mix of functions and Transit OrientedDevelopment (TOD) in typical Swedish neighborhoods.
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| 35. |
- Forssén, Jens, 1968, et al.
(författare)
-
Road traffic noise disease burden estimates for a model study of varying urban morphology cases
- 2021
-
Ingår i: Proceedings of INTER-NOISE 2021 - 2021 International Congress and Exposition of Noise Control Engineering. - : Institute of Noise Control Engineering (INCE).
-
Konferensbidrag (refereegranskat)abstract
- In a model study containing 31 different building morphologies in an urban setting, road traffic noise exposure has been calculated and analysed. For five of the building morphologies also vegetation surfaces on facades and roofs were studied. The facade exposure levels were analysed for both smaller (single-sided) flats and larger (floor-through) flats, considering the direct exposure from the roads as well as the non-direct exposure at noise-shielded positions like inner yards, applying a noise mapping software in combination with a prediction model for the non-direct exposure. Using noise indicators Lden and Lnight, the disease burden, in terms of DALY (Disability-Adjusted Life Years) per person, was estimated and analysed, via predictions of annoyance and sleep disturbance. As general trends, perimeter blocks were shown to perform better than morphologies with less enclosed yards and densification was shown to result in improved performance, assuming a constant traffic flow. In addition, complementing the perimeter blocks with towers was shown to enable improvement. Furthermore, traffic concentration by locating all local traffic to a single road was shown to be beneficial, increasingly so by widening the road. The use of facade vegetation was shown to result in significant overall improvement.
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| 36. |
- Armesto Barros, Jesús, et al.
(författare)
-
Recent and future trends of onshore wind turbine foundations
- 2022
-
Ingår i: Proceedings of the IABSE Symposium Prague 2022: Challenges for Existing and Oncoming Structures. - 9783857481819
-
Konferensbidrag (refereegranskat)abstract
- The decarbonization of the economy and the growing need for electricity are two trends that call for greener energy sources. Wind is a growing renewable energy source, which is expected to become the first source of power in the European Union in the next decade. In particular, onshore wind energy is expected to double by then. Fundamental structural components of wind turbines are their foundations, which are large structures associated with important material consumption and many construction challenges. The dimensions of these foundations are continuously increasing as turbines with taller towers and larger rotor diameters are being built. Designing cost- and material-efficient foundations is crucial to reduce the economic and environmental impact of wind energy. An important factor to successfully address these evolving requirements in the planning and design process is to build on the experience from previous projects. The aim of this work is to investigate the evolution of onshore wind turbines and its consequences on the design and climate impact of gravity foundations by analysing data from Swedish wind farms set in operation between 2013 and 2022. The evolution of turbine size, and foundation dimensions, reinforcement layout, material types and quantities, and embodied carbon are analysed in this paper.
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| 37. |
- Bergenram, Felicia, et al.
(författare)
-
Parametric Optimization of Slab Frame Bridges Considering Investment Cost, Environmental Impact and Buildability
- 2023
-
Ingår i: Procedia Computer Science. - 1877-0509.
-
Konferensbidrag (refereegranskat)abstract
- This paper presents research performed on set-based multi-criteria optimization for the preliminary design of slab frame bridges. As a result of immense CO2 emissions emerging from concrete production, there is a need for optimization methods decreasing the volume of concrete without affecting the function of the structure. Previous research suggests a general correlation between CO2 footprint- and cost reduction, due to minimized material use. However, the aspect of buildability may conflict with lessened material, as optimized designs might simultaneously be less buildable. This research aimed to develop an optimization method with respect to the investment cost and environmental impact while also considering buildability cost aspects. The optimization algorithm shows the possibilities of reducing the environmental impact by up to 13.7% for a slightly increased cost of 2.3%. Thus, by implementing optimization procedures in the early stages of the planning process the holistic cost effects related to green solutions can be presented, favoring the choice of sustainable designs amongst clients during tendering procedures.
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| 38. |
- Ek, Kristine, 1975, et al.
(författare)
-
Multi-criteria decision analysis methods to support sustainable infrastructure construction
- 2019
-
Ingår i: IABSE Symposium, Guimaraes 2019: Towards a Resilient Built Environment Risk and Asset Management - Report. ; , s. 1084-1091
-
Konferensbidrag (refereegranskat)abstract
- The construction of infrastructure projects represents a large sustainability impact, both positive and negative. Increased positive and reduced negative impacts can be achieved through better design and planning of the construction. To make more sustainable choices, well‐defined predictive sustainability assessment methods are required. Multi‐criteria decision analysis (MCDA) is a well-suited method for predictive sustainability assessment. This paper evaluates two MCDA methods for sustainability assessment of infrastructure construction and exemplifies their application with two case studies. The aim of this paper is to discuss if the methods are suitable for identifying the most sustainable alternative during the procurement process of an infrastructure project. It is recommended that MCDA methods are further developed to comply with the recently published EN standard on sustainability assessment of civil engineering works.
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| 39. |
- Heshmati, Mohsen, 1987, et al.
(författare)
-
HYGROTHERMAL DURABILITY OF ADHESIVELY BONDED FRP/STEEL JOINTS
- 2015
-
Ingår i: Implementing Innovative Ideas in Structural Engineering and Project Management. - : ISEC Press. - 9780996043717 ; , s. 75-80
-
Konferensbidrag (refereegranskat)abstract
- The use of fiber reinforce polymer, FRP, bonding to strengthen and repair deteriorated steel structures is increasing owing to its unique advantages over traditional strengthening and repair techniques. However, the lack of knowledge regarding environmental durability of adhesively bonded FRP/steel joints still hinders the widespread application of this method in steel structures. A number of studies have reported significant degradation of mechanical properties of these joints in hot and wet environments. In addition to that, the mechanisms of failure have been observed empirically to change from cohesive failure in the adhesive to apparent interfacial failure with increasing amount of moisture. This study presents the results of an experimental and numerical investigation to predict the mechanical behavior of FRP/steel joints after hygrothermal aging. First, moisture diffusion kinetics and mechanical degradation of a two-part commercially available epoxy adhesive and Carbon FRP material were experimentally characterized over a wide range of temperature and humidity conditions. These parameters were then incorporated in a coupled 3D diffusion-mechanical finite element, FE, model. In addition, bonded double-lap shear joints of CFRP/steel were aged for up to a year and tested to failure. It is found that the presence of moisture for less than a critical period can increase the joint strength. However, prolonged exposure to the same moisture content degrades the load-carrying capacity of the joint.
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| 40. |
- Mathern, Alexandre, 1986, et al.
(författare)
-
Sustainability-driven structural design using artificial intelligence
- 2019
-
Ingår i: 20th Congress of IABSE, New York City 2019: The Evolving Metropolis - Report. ; , s. 1058-1065
-
Konferensbidrag (refereegranskat)abstract
- The construction industry is responsible for a large share of the global environmental impact. The need for addressing sustainability and increased competition calls for the development of innovative design methods that include sustainability in a transparent way. The aim of this work is to propose a framework to use machine learning and artificial intelligence (AI) for structural design optimization based on sustainability and buildability criteria. AI opens up new possibilities to optimize and assess structures early in the planning and design stages. In that way, it is possible to decrease the negative and enhance the positive environmental, economic and social impacts and create a more time‐ and cost‐effective design process. The work is meant to serve as a first step toward the development of AI‐based methods in the construction industry, which can bring digitalization in the construction industry to a new level and create new services and business models.
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| 41. |
- Rempling, Rasmus, 1976, et al.
(författare)
-
Automatic structural design by a set-based parametric design method
- 2019
-
Ingår i: Automation in Construction. - : Elsevier BV. - 0926-5805. ; 108:December
-
Tidskriftsartikel (refereegranskat)abstract
- Modern structural design faces new challenges, such as addressing the needs of several stakeholders and satisfying the criteria for achieving sustainability. The traditional design process does not allow resolution of these challenges. The purpose of this project was to investigate the applicability of a Set-Based Parametric Design method to the structural design process of bridges. The focus was on the early design stage, in which the design team evaluates design alternatives against a chosen set of criteria. The main challenge in this stage of design is that the process should be cost- and time-effective while allowing comparison of the different alternatives and their evaluation in terms of the different design criteria. Certainly, structural design is often performed by a discussion between the different stakeholders involved in this process, i.e. the client, contractor, and engineering team. An evaluation of alternatives against criteria requires a more detailed design, which is contradictory to the early design stage when information is scarce. The selected approach was to develop a script that can generate information for decision-making, automate the structural design process, perform common routine design tasks, and control the numerical analysis. The method combined Set-Based Design, Parametric Design, Finite Element Analysis and Multi-Criteria Decision Analysis. Three existing bridges were selected to demonstrate the applicability of the developed method. The method was successfully applied and it was observed that it resulted in bridges that were more efficient in terms of material costs and carbon dioxide equivalent emissions compared with existing bridges. By delaying the decisions and developing the sets of alternatives, various alternatives can be assessed and evaluated, in the design stage, against different sustainability criteria.
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| 42. |
- Varga, Balázs, 1990, et al.
(författare)
-
Data-driven distance metrics for kriging - Short-term urban traffic state prediction
- 2023
-
Ingår i: IEEE Transactions on Intelligent Transportation Systems. - 1524-9050 .- 1558-0016. ; 24:6, s. 6268-6279
-
Tidskriftsartikel (refereegranskat)abstract
- Estimating traffic flow states at unmeasured urban locations provides a cost-efficient solution for many ITS applications. In this work, a geostatistical framework, kriging is extended in such a way that it can both estimate and predict traffic volume and speed at various unobserved locations, in real-time. In the paper, different distance metrics for kriging are evaluated. Then, a new, data-driven one is formulated, capturing the similarity of measurement sites. Then, with multidimensional scaling the distances are transformed into a hyperspace, where the kriging algorithm can be used. As a next step, temporal dependency is injected into the estimator via extending the hyperspace with an extra dimension, enabling for short horizon traffic flow prediction. Additionally, a temporal correction is proposed to compensate for minor changes in traffic flow patterns. Numerical results suggest that the spatio-temporal prediction can make more accurate predictions compared to other distance metric-based kriging algorithms. Additionally, compared to deep learning, the results are on par while the algorithm is more resilient against traffic pattern changes.
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| 43. |
- Albrecht, Martin
(författare)
-
System innovation dynamics around electric vehicles. The cases of Norway, Denmark and Sweden.
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This paper focuses on the comparison of electric car innovation patterns in Norway, Sweden and Denmark. Doing so, it takes a closer look at what the most essential dynamics in the systems were over time and what enabled those dynamics. The main research aim is to contribute to a wider understanding of why Norway is so much ahead of Sweden and Denmark in electric car adoption. The purpose is also to adopt a perspective that goes beyond a mere focus on economic policy instruments. In order to do so different theory elements are combined in a framework. These elements stem from the transition theory literature field, especially the technological innovation system (TIS) and the multi-level perspective (MLP). This combination allows analysing the development behind a dynamic, not just when it comes to an innovation itself but also with regards to the established regime. The data is gathered through analysis of existing documents and data as well as a series of 27 expert interviews conducted in the three case countries. The findings suggest that there are important differences in transition patterns that can account for the electric vehicle (EV) diffusion situation we can find nowadays in the three Nordic countries. An important stepping stone was the need for a very strong legitimacy of the original EV vision that is also anchored in a coordinated, sector overarching coalition of actors that thinks strategically and long term. Moreover some general beneficial dynamics could be identified across the countries in question. In Norway these beneficial dynamics can be summarised as a systems motor, in Denmark as a failed entrepreneurial motor that shifted towards a constrained municipal motor and in Sweden as a loosely, coordinated and weaker version of a systems motor.
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| 44. |
- Petersson, Jesper, 1974, et al.
(författare)
-
Defend, Retreat and Attack: Urban Waters and Valuation Practices
- 2022
-
Ingår i: Water Alternatives. - : Water Alternatives Association. - 1965-0175. ; 15:1, s. 175-192
-
Tidskriftsartikel (refereegranskat)abstract
- This paper explores the river landscapes and concomitant values resulting from tensions between flood management and visions of a River City. The aim is to contribute to an understanding of the management of urban waters as valuation practices. We regard valuation practices as co-constitutive of current and future river landscapes. Sweden’s second-largest city, Gothenburg, is located next to the sea, and the Göta River, Sweden’s largest water system, runs through it. Our empirical focus is on how this city approaches increasing risks of flooding. We explore three approaches that have been formulated in relation to flood management: defend, retreat and attack. We ask how these approaches are applied in the management of Göta River flooding and in the city’s vision of a future Gothenburg that embraces the river as a genuinely positive aspect of urban life. We present the case as a journey that takes us upstream from the river’s sea inlet port and through Gothenburg. During our kilometre by kilometre journey, the river’s appearance shifts. The varied river landscape mirrors the diversity in how its waters are valuated, both historically and in present times. The perception of urban waters is shaped by practices of valuation. These valuations are generative. They connect the value of water to other entities, actors, plans, activities and buildings, and they are thus key to the river landscapes that will eventually be realised. By way of conclusion, we identify a number of governance challenges that are particularly relevant to urban rivers.
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| 45. |
- Crocetti, Roberto, et al.
(författare)
-
Stress-laminated-timber decks: state of the art and design based on Swedish practice
- 2016
-
Ingår i: European Journal of Wood and Wood Products/Holz als Roh - und Werkstoff. - : Springer Science and Business Media LLC. - 1436-736X .- 0018-3768. ; 74:3, s. 453-461
-
Tidskriftsartikel (refereegranskat)abstract
- Stress-laminated-timber (SLT) bridge decks area valid alternative to conventional short- and medium-spanbridges in terms of cost and performance. SLT decks aremade from a number of planks or glulam beams positionedside by side and stressed together using high-strength steelbars. A concentrated load can therefore be distributed fromthe loaded beams onto adjacent beams due to the resistingfriction caused by the pre-stressing of all beams in thedeck. This paper describes the state of the art of SLT bridgedecks, with special emphasis on Swedish practice. Theeffect of butt joints on deck deflection and solution appliedto accommodate the loss of pre-stress are shown. Simpledesign tools for the preliminary design of road bridges areillustrated. Best practice with regard to some detailing,water protection and durability is also discussed. Finally,possible developments of SLT bridges are discussed.
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| 46. |
|
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| 47. |
- Khosravi, Mahdi, 1988-, et al.
(författare)
-
Assessment of Railway Track Preventive and Corrective Tamping Recovery
- 2023
-
Konferensbidrag (refereegranskat)abstract
- Railway track, as a critical infrastructure, plays a significant role in freight transportation. However, Railway track degrades with age and usage and can impact negatively track availability and safety. Tamping actions are used to rejuvenate the degradation and recover the functionality of the track to an acceptable level. Tamping actions are performed in a form of preventive and corrective regimes. In performing an effective tamping regime, the recovery of both preventive and corrective tamping should be taken into account. In addition, the occurrence of isolated defects should be considered. By combining the recovery model with the degradation model, the long-term behavior of the track geometry can be predicted, and an accurate estimation of tamping needs can be provided, leading to optimum tamping scheduling. In this study, the effects of tamping recovery are modeled for both preventive and corrective strategies. For this aim, the values of both standard deviation (SD) and isolated defects have been predicted and their values before tamping are used as explanatory variables in a multivariable regression model. Finally, the effect of tamping recovery on the values of both SD and isolated defects is estimated. A case study is performed on a heavy haul line located in Sweden’s rail network to evaluate the performance of the proposed multivariable regression model. Observations showed that the model and its coefficients are significant with P-values close to zero, and the R-squared value suggests that the model explains approximately 70% of the variability in the response variable recovery.
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| 48. |
- Curtis, Carey, et al.
(författare)
-
Public Transport Accessibility Tools Matter: A case study of Gothenburg, Sweden
- 2019
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Ingår i: Case Studies on Transport Policy. - : Elsevier BV. - 2213-624X. ; 7:1, s. 96-107
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Tidskriftsartikel (refereegranskat)abstract
- Urban transport investment decision-making has relied on traditional modelling tools that forecast travel demand based on existing travel patterns. This approach has also underpinned decisions about future urban development. Latent travel demand is poorly understood, and this is particularly important given policy aspirations for the take-up of more sustainable transport modes such as public transport. Accessibility tools can make an important contribution to future development and investment decisions given this policy aspiration. In this paper, public transport supply is assessed using an accessibility tool and then compared to travel patterns. By assessing both public transport supply and travel demand through an accessibility lens we are able to gain insight into the latent demand for public transport. An innovative segmentation type approach is employed by comparing supply and demand and from this a typology is proposed as a framework for a more holistic public transport investment strategy. This takes into account public transport accessibility, travel demand of trip makers and their socio-economic situation, set in the context of the urban region.
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| 49. |
- Mirnig, Alexander G., et al.
(författare)
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External communication of automated shuttles: Results, experiences, and lessons learned from three European long-term research projects
- 2022
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Ingår i: Frontiers Robotics AI. - : Frontiers Media SA. - 2296-9144. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Automated shuttles are already seeing deployment in many places across the world and have the potential to transform public mobility to be safer and more accessible. During the current transition phase from fully manual vehicles toward higher degrees of automation and resulting mixed traffic, there is a heightened need for additional communication or external indicators to comprehend automated vehicle actions for other road users. In this work, we present and discuss the results from seven studies (three preparatory and four main studies) conducted in three European countries aimed at investigating and providing a variety of such external communication solutions to facilitate the exchange of information between automated shuttles and other motorized and non-motorized road users.
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| 50. |
- Aldenlöv, Jens, et al.
(författare)
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Public procurement of railway infrastructuremaintenance : a literature review
- 2017
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Ingår i: Proceedings of the 9th Nordic Conference on Construction Economics and Organization. - Lyngby : Polyteknisk Boghandel og Forlag. - 9788750211259 ; , s. 10-21
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Konferensbidrag (refereegranskat)abstract
- The maintenance of railway infrastructure has in several instances been changed from government-based to being based on public procurement, with varying degrees of flexibility for the contractor to design their maintenance work. The purpose of-giving contractors a larger freedom of choice of how to perform maintenance is to stimulate them to innovate and develop their maintenance processes. Since the contracts differ in between and there are changes in government policies over time that affects both existing and new contracts, a comparison between different contracts becomes challenging. A literature review has been conducted to understand the change in procurement strategy and how to encourage contractors to innovate. The research questions include: What procurement strategies are there? How is maintenance evaluated? How does procurement affect the innovation opportunities for entrepreneurs?The literature review focuses on railway maintenance and contract design between client and contractor. In total, 17 articles matched the search criteria and were selected for the review. To have successful maintenance service, five articles suggested partnering as a strategy with common goals in combination with good communication during the entirety of the contract. When selecting incentive plan, four articles mentions that a focus on performance-based incentives in combination with riskmanagement is better rather than actual payment schemes. The reason being that payment is often themain cause of conflicts between client and contractor. The scientific literature suggests that improvement in incentives improves quality of maintenance, decreases delays and technical failures. The conclusion from the literature review is that partnering in railway maintenance is considered successful. With accurate knowledge about railway assets the incentive plan becomes accurate which reduces costs.The literature review is a part of a research project with an overall goal to develop a model to guide the selection of appropriate type of procurement strategy, contract and control of maintenance for a moresustainable railway system.
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