| 1. |
- Ahmed, Samih, et al.
(författare)
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Post-Tensioned Stress Ribbon Systems in Long Span Roofs
- 2019
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Ingår i: 20th Congress of IABSE, New York City 2019. - : International Association for Bridge and Structural Engineering. - 9783857481659 ; , s. 534-540
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Konferensbidrag (refereegranskat)abstract
- Cable systems have numerous advantages, such as: large column-free areas, and reduced materials consumption, which reduces the load and the cost. Nevertheless, they are rarely used in long span roofs due to large deflections, and the insufficient space for end supports, or/and back-stayed cables. This work suggests the use of post-tension stress ribbon system in long span roofs in order to reduce the pull-out forces, deflections and concrete stresses compared to a conventional cable system. A comparison is carried out through meticulous and accurate finite element simulations, using SAP2000, implemented for the new +200m roof of Västerås Travel Center (Sweden), which will become one of the longest cable suspended roofs in the world, if not the longest. Results confirm the suitability and superiority of stress ribbon systems as it reduces concrete stresses, deflections, pull-out forces and vertical reactions. These reductions are found highly correlated to the applied prestressing forces.
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| 2. |
- Carro-López, D., et al.
(författare)
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An old bridge transformed into a new one : Possible, recommendable?
- 2019
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Ingår i: 20th Congress of IABSE, New York City 2019. - : International Association for Bridge and Structural Engineering (IABSE). - 9783857481659 ; , s. 951-956
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Konferensbidrag (refereegranskat)abstract
- There is an extensive network of reinforced concrete bridges that give service to roads, highways and railways. These structures where constructed with quality standards of the past, and they suffer of severe problems. Now we consider the idea of substituting them with structural elements with much longer service life. However, there is an important question to be addressed in this area: what to do with the existing infrastructure that would be demolished. Even more if we consider environmental issues. One good example of this recurrent problem could be found in the case of the Gullspång bridge (Sweden). It was constructed in 1935 and it was severely damaged with corrosion. The administration decided in the 2016 that no further repair would be done and that the bridge would be demolished and a new erected in substitution. A fraction of the concrete from the old bridge was crushed and processed to produce new aggregate. With this aggregate, using the coarse fraction, it was analyzed the structural effect of replacing natural aggregates with these recycled aggregates. The performance of the new structural elements was positive, and it seems that a high percentage of the natural aggregates could be replaced with recycled ones.
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| 3. |
- Ekström, Daniel P T, 1976, et al.
(författare)
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Predicting project performance using pre-construction performance indicators - A case study evaluation
- 2019
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Ingår i: 20th Congress of IABSE, New York City 2019: The Evolving Metropolis - Report. - 9783857481659 ; , s. 1438-1443
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Konferensbidrag (refereegranskat)abstract
- Predicting the outcome of a construction project largely relies on estimated targets of time and cost. Still, hitting the targets does not mean that the project is a success on all performance levels. Here, a retrospective case study was undertaken on a construction project identified as a successful project by the partners involved. The purpose of the study was to validate conceptual design indicators of a high-performance construction project as reported in the literature, by answering the following research questions: "What characterizes the dialogue between the different disciplines; (2) What is the dialogue about; and (3) When in the process do questions arise?" Findings indicate that the interprofessional dialogue within the project team was well established. The paper introduces a discussion that the dialogue benefited from the collaborative project environment as well as the early design intent. Further, the study also suggests that the interprofessional dialogue supported a sound project team development.
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| 4. |
- Gottsäter, Erik, et al.
(författare)
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Crack widths in portal frame bridges subjected to restraint effects
- 2019
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Ingår i: 20th Congress of IABSE, New York City 2019: The Evolving Metropolis - Report. ; , s. 1101-1105, s. 1101-1105
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Konferensbidrag (refereegranskat)abstract
- Restraint stresses appear in structural parts which are prevented from adjusting their shape when subjected to e.g. shrinkage or thermal actions. If the restrained stresses are large, cracking might occur, which can affect the durability of the structure. In the case of restraint effects, the reinforcement required in a bridge to limit the crack widths can be difficult to determine, as the magnitude of the restraint stresses depend on the stiffness of the structure. If cracking occurs, the stiffness is reduced and thereby also the stresses. For this reason, in structural parts affected by restraint effects, it can be hard to estimate both the number of cracks that will appear and the resulting restraint stress that governs the crack widths. In this study, crack widths in a portal frame bridge subjected to thermal actions and shrinkage were investigated using non-linear FE analysis. A bond-slip relation was used for concrete-reinforcement interaction, as the resulting crack spacing was unknown. Corresponding analysis was performed using linear elastic material models and hand calculations of crack widths, for two different thermal load cases, and relations between the results from the different methods are presented. The result can lead to the development of a more accurate design model, which would lead to more efficient use of reinforcement.
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| 5. |
- Honfi, Daniel, et al.
(författare)
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A practical approach for supporting decisions in bridge condition assessment and monitoring
- 2019
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Ingår i: 20th Congress of IABSE, New York City 2019. - : International Association for Bridge and Structural Engineering (IABSE). - 9783857481659 ; , s. 2137-2142, s. 2137-2142
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Konferensbidrag (refereegranskat)abstract
- In this contribution a practical and rational decision-making approach is presented to be applied for common bridges typically managed by public authorities. The authors have developed a model with the intention to be applicable for practical cases for common bridges in the daily work of bride operators responsible for a large number of assets, yet still maintain the principles of more generic frameworks based on probabilistic decision-theory. Three main attributes of the verification of sufficiency of structural performance are considered, namely: 1) the level of sophistication of modelling performance, 2) the degree of verification and acceptance criteria in terms of dealing with uncertainties and consequences, 3) the extent of information is obtained and incorporated in the verification. The simplicity of the approach is demonstrated through an illustrative case study inspired by practical condition assessment decision problems. It is argued that in practical cases it may be desirable to utilize less advanced methods owing to constraints in resources or lack of reliable data (e.g. based on structural health monitoring or other on-site measurement techniques).
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