| 1. |
- Flansbjer, Mathias, et al.
(författare)
-
Structural Concept of Novel RPC Sandwich Façade Elements with GFRP Connectors
- 2016
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Ingår i: IABSE Congress Stockholm 2016. - : IABSE c/o ETH Hönggerberg. - 9783857481444 ; , s. 2164-2171
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Konferensbidrag (refereegranskat)abstract
- The SESBE research project aims to develop novel smart sandwich façade elements with high insulating capabilities while providing a reduced thickness in conjunction with superior mechanical and durability properties. The present paper mainly focuses on the verification of the mechanical performance of the glass fibre reinforced polymer (GFRP) connectors in the façade element composed of reactive powder concrete (RPC) panels with foam concrete insulation between them. Because of the reduced thickness of the large façade elements, the performance of the connectors is critical for the entire structural concept. A description of structural performance and results based on experimental methods and finite element (FE) analysis are presented.
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| 2. |
- Flansbjer, Mathias, et al.
(författare)
-
Strutural performance of GFRP connectors in Composite sandwich facade elements
- 2016
-
Ingår i: Journal of Facade Design and Engineering. - 2213-302X .- 2213-3038. ; 4:1-2, s. 35-52
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Tidskriftsartikel (refereegranskat)abstract
- A systematic testing and modelling program has been developed for the verification of the structural performance of facade sandwich elements to take structural aspects into consideration in the SESBE research project, focusing on the development of “smart” facade elements.The present paper mainly focuses on the verification of the mechanical performance of the glass fibre reinforced polymer (GFRP) connectors of the novel type of facade element composed of reactive powder concrete (RPC) panels with foam concrete insulation between them. Because of the reduced thickness of the large facade elements, the performance of the connectors is critical for the entire structural concept. The first series of the testing and modelling programme concerning connector performance are presented here. The results suggest that sufficient strength and ductility of the connectors can be ensured using GFRP in the proposed thin light-weight facade elements.
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| 3. |
- Vennetti, Daniel, et al.
(författare)
-
Safety of temporary stands
- 2016
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Ingår i: IABSE Congress Stockholm 2016. - 9783857481444 ; , s. 2788-2795
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Konferensbidrag (refereegranskat)abstract
- The paper gives an overview of some relevant technical aspects related to temporary stands. Since these kinds of structures are often used by a large number of people, consequences of structural failure could be significant. However, the effort put into their design and maintenance is often less than in case of permanent structures. Furthermore, it is not always clear who bears the responsibility if accidents happen. The current study concludes that the structural behaviour of these systems is much more complex than one might think; therefore clear regulations, guidelines and approaches are needed. A major concern is the requirements for validation of structural performance by numerical modelling and testing. Improvements in standardisation also require further research in several areas, such as e.g. structural dynamics, nature of loads, requirements, human-structure interaction.
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| 4. |
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| 5. |
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| 6. |
- Bedon, Chiara, et al.
(författare)
-
Numerical Modelling of Structural Glass Elements under Thermal Exposure
- 2018
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Konferensbidrag (refereegranskat)abstract
- Glass is largely used in engineering applications as a structural material, especially for laminated glass (LG) sections. However, the well-known temperature-dependent behaviour of visco-elastic interlayers for LG sections should be properly accounted for safety purposes, even in ambient conditions. The materials thermo-mechanical degradation with increase of temperature could further severely affect the load-bearing performance of such assemblies. Thermo-mechanical Finite Element (FE) numerical modelling, in this regard, can represent a robust tool and support for designers. Key input parameters and possible limits in FE models, however, should be properly taken into account and calibrated, especially for geometrically simplified models, to enable realistic and reliable estimations of real structural behavior. In this paper, FE simulations are proposed for monolithic (MG) and LG specimens under radiant heating, based on one-dimensional (1D) models. With the use of experimental results from the literature, parametric studies are discussed, indicating limits and issues at several modelling assuptions. Careful consideration is paid for various thermal material properties (conductivity, specific heat), boundary conditions (conductivity, emissivity) as well as geometrical features (thickness tolerances, etc.) and composition of LG sections (interlayer type, thickness). Comparative parametric results are hence discussed in the paper.
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| 7. |
- Bedon, Chiara, et al.
(författare)
-
Performance of structural glass facades under extreme loads – Design methods, existing research, current issues and trends
- 2018
-
Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 163, s. 921-937
-
Tidskriftsartikel (refereegranskat)abstract
- Glass has been overwhelmingly used for windows and facades in modern constructions, for many practical reasons, including thermal, energy, light and aesthetics. Nevertheless, due to the relatively low tensile strength and mostly brittle behaviour of glass, compared to other traditional materials, as well as to a multitude of interacting structural and non-structural components, windows/facades are one of the most fragile and vulnerable components of buildings, being representative of the physical line of separation between interior and exterior spaces. As such, multidisciplinary approaches, as well as specific fail-safe design criteria and analysis methods are required, especially under extreme loading conditions, so that casualties and injuries in the event of failure could be avoided and appropriate safety levels could be guaranteed. In this context, this paper presents a review of the state of art on analysis and design methods in use for glass facades, with careful consideration for extreme loading configurations, including natural events, such as seismic events, extreme wind or other climatic exposures, and man-made threats, i.e. blast loads and fire. Major results of available experimental outcomes, current issues and trends are also reported, summarising still open challenges.
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| 8. |
- Bedon, Chiara, et al.
(författare)
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Structural characterisation of adaptive facades in Europe – Part I : Insight on classification rules, performance metrics and design methods
- 2019
-
Ingår i: Journal of Building Engineering. - : Elsevier BV. - 2352-7102. ; 25
-
Tidskriftsartikel (refereegranskat)abstract
- Adaptive facades are increasingly used in modern buildings, where they can take the form of complex systems and manifest their adaptivity in several ways. Adaptive envelopes must meet the requirements defined by structural considerations, which include structural safety, serviceability, durability, robustness and fire safety. For these novel skins, based on innovative design solutions, experimentation at the component and / or assembly level is required to prove that these requirements are fulfilled. The definition of appropriate metrics is hence also recommended. A more complex combination of material-related, kinematic, geometrical and mechanical aspects should in fact be properly taken into account, compared to traditional, static facades. Accordingly, specific experimental methods and regulations are required for these novel skins. As an outcome of the European COST Action TU1403 ‘Adaptive facades network’ - ‘Structural’ Task Group, this paper collects some recent examples and design concepts of adaptive systems, specifically including a new classification proposal and the definition of some possible metrics for their structural performance assessment. The aim is to provide a robust background and detailed state-of-the-art information for these novel structural systems, towards the development of standardised and reliable procedures for their mechanical and thermo-physical characterisation.
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| 9. |
- Bedon, Chiara, et al.
(författare)
-
Structural characterisation of adaptive facades in Europe - Part II : Validity of conventional experimental testing methods and key issues
- 2019
-
Ingår i: Journal of Building Engineering. - : Elsevier Ltd. - 2352-7102. ; 25
-
Tidskriftsartikel (refereegranskat)abstract
- Given their intrinsic features, adaptive facades are required to satisfy rigid structural performances, in addition to typical insulation, thermal and energy requirements. These include a minimum of safety and serviceability levels under ordinary design loads, durability, robustness, fire resistance, capacity to sustain severe seismic events or other natural hazards, etc. The overall design process of adaptive facades may include further challenges and uncertainties especially in the case of complex assemblies, where multiple combinations of material-related phenomena, kinematic effects, geometrical and mechanical characteristics could take place. In this context, experimental testing at the component and/or at the full-scale assembly level has a fundamental role, to prove that all the expected performance parameters are properly fulfilled. Several standards and guideline documents are available in the literature, and provide recommendations and procedures in support of conventional testing approaches for the certification and performance assessment of facades. These documents, however, are specifically focused on ordinary, static envelopes, and no provisions are given for the experimental testing of dynamic, adaptive skins. In this regard, it is hence expected that a minimum of conventional experimental procedures may be directly extended from static to dynamic facades. However, the validity of standardized procedures for adaptive skins is still an open issue. Novel and specific experimental approaches are then necessarily required, to assess the structural characteristics of adaptive facades, depending on their properties and on the design detailing. In this paper, existing fundamental standards for testing traditional facades are first recalled and commented. Special care is spent for the validity and reliability of conventional testing methods for innovative, adaptive envelopes, including a discussion on selected experimental methods for facade components and systems. Non-conventional testing procedures which may be useful for adaptive skins are then also discussed in the paper, as resulting from the research efforts of the European COST Action TU1403 ‘Adaptive facades network’ - ‘Structural’ Task Group.
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| 10. |
- Bedon, Chiara, et al.
(författare)
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Thermal assessment of glass façade panels under radiant heating : Experimental and preliminary numerical studies
- 2018
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Ingår i: Journal of Facade Design and Engineering. - 2213-302X. ; 6:3, s. 049-064
-
Tidskriftsartikel (refereegranskat)abstract
- Nowadays, glass is increasingly being used as a load-bearing material for structural components in buildings and façades. Different structural member solutions (such as panels, beams, columns) and loading conditions were the subjects of several research studies in recent years. Most of them, however, were typically limited to experimental testing and numerical simulations on glass elements and assemblies at room temperature. Thermo-mechanical investigations, inclusive of the temperature-dependent behaviour of visco-elastic interlayers used in laminated glass solutions, as well as the typical thermo-mechanical degradation of glass properties in line with temperature increase, in this regard, are still limited. Such an aspect can be particularly important for adaptive façades, in which the continuous variation of thermal and mechanical boundary conditions should be properly taken into account at all the design stages, as well as during the lifetime of a constructed facility. Given the key role that thermo-mechanical studies of glazing systems can pe use of glass in façades, this paper focuses on Finite Element (FE) numerical modelling of monolithic and laminated glass panels exposed to radiant heating, by taking advantage of past experimental investigations. In the study discussed herein, being representative of some major outcomes of a more extended research project, one-dimensional (1D) FE models are used to reproduce the thermal behaviour of selected glass specimens under radiant heating, as observed in the past experiments. Given the high computational efficiency but very basic assumptions of 1D assemblies, a critical discussion of experimental-to-numerical comparisons is then proposed for a selection of specimens.
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| 11. |
- Björnsson, Ivar, et al.
(författare)
-
Decision support framework for bridge condition assessments
- 2019
-
Ingår i: Structural Safety. - : Elsevier BV. - 0167-4730 .- 1879-3355. ; 81
-
Tidskriftsartikel (refereegranskat)abstract
- An essential aspect in the maintenance of existing bridges is the ability to adequately and accurately assess and evaluate the condition of the structure. Condition assessments, which can be carried out in any number of ways, provide valuable information concerning the actual state of a bridge, including the severity of potential damages, and form the basis for further maintenance decisions. Any decision support concerning the management of existing structures thus requires attention towards the uncertainties associated with the assessment methods when applied in practice as well as the maintenance actions these support. These uncertainties cannot be solely described as model uncertainties but are also a result of the variation in engineering performance observed in practice. In the current paper a rational and systematic framework is presented which provides practical decision support concerning whether condition assessments are necessary, what assessment methods are recommended, if invasive actions are needed, or if some other non-invasive option may be more appropriate. The framework takes into account three main attributes of an enhanced condition assessment, namely, modelling sophistication, considerations of uncertainties and risks, and knowledge/information content. Increasing the level of one or more of these attributes may be advantageous only if the expected benefits or added value of information is considered appropriate in relation to the cost of implementation in practice. A decision making model, based on Bayesian decision theory, is adopted to evaluate this problem. Two case studies, in which the framework is applied, are provided for illustrative purposes; the first is a generic numerical example and the second a decision scenario related to the fatigue assessment of an existing railway bridge.
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| 12. |
- Björnsson, Ivar, et al.
(författare)
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Suitable degree of crudeness in engineering practice
- 2019
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Ingår i: IABSE Symposium, Guimaraes 2019. - : International Association for Bridge and Structural Engineering (IABSE). - 9783857481635 ; , s. 1592-1599
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Konferensbidrag (refereegranskat)abstract
- Practicing structural engineers may be familiar with the main principles of structural reliability but may not necessarily be experts in using such methods. This may lead to a lack in understanding the effect of uncertainties on the ensuing structural safety and to sub-optimization of more traditional structural engineering aspects. The aim of the current paper is to highlight the importance of considering risks and uncertainties in design and to improve the awareness of practicing engineers to such considerations. The importance of a consistent treatment of uncertainties in structural engineering is brought to attention with focus on the modelling approaches which often underlie decisions. Different aspects discussed are: decision making in light of uncertainty, principles of consistent crudeness and the influence of engineering performance in practice on the safety of structures. A simplified model, considering strategies for improving engineering models, is considered and examples, based on simplified decision models, are also provided.
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| 13. |
- Blomfors, Mattias, 1990, et al.
(författare)
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Engineering Assessment Method for Anchorage in Corroded Reinforced Concrete
- 2016
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Ingår i: IABSE Congress Stockholm 2016. - : IABSE c/o ETH Hönggerberg. - 9783857481444 ; , s. 2109-2116
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Konferensbidrag (refereegranskat)abstract
- There is an increasing need for reliable methods to assess load-carrying capacity and remaining service life of existing infrastructure. Several previous research projects have resulted in a verified, simple 1D model for assessment of anchorage in corroded reinforced concrete structures. Previous verification has involved both experiments and detailed 3D NLFE analyses. To further develop the 1D model it needs to be extended to comprise more practical situations. In order to facilitate an efficient extension procedure in the future, the size of 3D NLFE model that is required to capture the bond behaviour between corroded reinforcement and concrete is investigated. Beam-end models and models of sub-sections were studied, and the results in terms of bond stress and crack pattern were compared. Preliminary results indicate good agreement for some situations; however for some cases a section model seems to overestimate the capacity.
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| 14. |
- Blomfors, Mattias, 1990, et al.
(författare)
-
Partial safety factors for the anchorage capacity of corroded reinforcement bars in concrete
- 2019
-
Ingår i: Engineering structures. - : Elsevier BV. - 0141-0296 .- 1873-7323. ; 181, s. 579-588
-
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. |
- Blomfors, Mattias, 1990, et al.
(författare)
-
Practical bond model for corroded RC bridges
- 2017
-
Ingår i: High Tech Concrete. - Cham : Springer International Publishing. - 2617-4820. - 9783319594705 ; , s. 1793-1803
-
Konferensbidrag (refereegranskat)abstract
- Corrosion of steel reinforcement is a common cause of deterioration in reinforced concrete bridges and many existing bridges are damaged to varying degrees. The rate of deterioration of the bridge stock has been shown to increase due to climate change. Unsympathetically, the demand for load-carrying capacity is however often increased with time. Therefore there is an increasing need for reliable methods to assess the load-carrying capacity and remaining service-life of existing infrastructure. A simple model for the assessment of Anchorage in corroded Reinforced Concrete structures (ARC) has previously been developed. It was originally based on fib Model Code 1990 and has been verified with experiments and three-dimensional nonlinear finite element (3D NLFE) analyses for both accelerated and natural corrosion as well as for different degrees of corrosion. The model was applied when assessing two road bridges in Sweden. The investigation demonstrated great cost savings but also areas for improvement, in particular regarding (a) applicability to practical cases and (b) incorporation of uncertainties in the assessment. The primary focal point of this paper is to present an overview of the development of the ARC model together with recent verifications against a large bond test database as well as foreseen future developments. It was found that the ARC model represents the physical behaviour reasonably well, and gives conservative values of bond strength compared to the bond tests database. In future works, among others, uncertainties of the input variables will be incorporated by means of probabilistic modelling, making way for implementation of the ARC model into semi-probabilistic safety concepts by extraction of modification factors. Overall, with more accurate and reliable assessment methods for corroded RC structures, environmental and economic savings are imminent as more of the potential of existing structures can be realized.
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| 16. |
- Blomfors, Martin, et al.
(författare)
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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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| 17. |
- Blomfors, Mattias, 1990, et al.
(författare)
-
Reliable engineering assessments of corroded concrete structures
- 2017
-
Ingår i: Nordic Concrete Research : Proceedings of the XXIII Nordic Concrete Research Symposium, Aalborg, Denmark, 21-23 August, 2017 - Proceedings of the XXIII Nordic Concrete Research Symposium, Aalborg, Denmark, 21-23 August, 2017. ; , s. 245-248
-
Konferensbidrag (refereegranskat)abstract
- Corrosion of steel reinforcement is a large and increasing problem for reinforced concrete structures. Simple and reliable assessment methods are required to use the full capacity of existing infrastructure. In this paper, a reliable engineering assessment method is outlined. A model for anchorage has been developed and verified against a large database of bond tests. Also the influence of corrosion on the bending and shear capacity is to be included, and a probabilistic model will be established. The outcome of this work will enable practising engineers to perform reliable assessments of concrete structures with corroded reinforcement.
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| 18. |
- Blomqvist, Lars, 1962-, et al.
(författare)
-
Spin-off från möbelindustrin till byggbranschen
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- There is a deficit of housing in Sweden and it is built too little to compensate for this according to the National Board of Housing, Building and Planning, which, among other things, indicate resource shortages as a reason.The furniture and construction industry have much in common. However, the furniture industry has a larger share of industrial production, which means production at a lower cost. By retrieving production ideas in other industries, there is an opportunity to radically renew and transform the (wood) construction industry and thus streamline the construction process. Historically, cross-sectoral spin-off effects have been shown to generate success factors.The goal of this project is to develop prototypes for building connections inspired by the furniture and interior industry and explore them together with industry actors. This, in turn, serves as an inspiration for a larger project, together with industry actors aiming at developing systems for assembly of building elements, which provide higher precision and are faster to perform than today's system. The pilot developed in this project shows that the idea is ripe for a more full-scale investigation.
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| 19. |
- Cabrero, Jose Manuel, et al.
(författare)
-
A probabilistic study of brittle failure in dowel-type timber connections with steel plates loaded parallel to the grain
- 2019
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Ingår i: Wood Material Science and Engineering. - : Informa UK Limited. - 1748-0272 .- 1748-0280. ; 14:5, s. 298-311
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Tidskriftsartikel (refereegranskat)abstract
- Dowel-type connections in timber structures should be typically designed in a way that, if the load bearing capacity is exceeded, desirable ductile failure should likely occur, i.e. yielding of the metal dowel or embedment of the timber. However, the probability of brittle failures cannot be completely avoided in many cases. If the connection is loaded parallel to the grain direction, splitting, row-shear, plug/block shear and tensile failure are examples of such brittle failure modes. To ensure a beneficial structural performance locally and sufficient structural robustness globally, the probability of such brittle failures should be kept at a sufficiently low level. However, in the current version of EN1995, the probability of such failure is not considered explicitly. The final aim of the presented research study is to develop a rational approach for the consideration of brittle failure in timber connections with dowel-type fasteners and steel plates loaded parallel to the grain, consistently with the partial factor method. As a first step, a probabilistic model has been used to study the susceptibility to brittle failure and provide a rational basis for the calibration of a “brittle overstrength factor”. The results of this study are reported in the current contribution.
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| 20. |
- Debuyser, Michael, et al.
(författare)
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Behaviour of monolithic and laminated glass exposed to radiant heating
- 2017
-
Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 130, s. 212-229
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Tidskriftsartikel (refereegranskat)abstract
- Glass is seeing a growing interest as a structural material as a result of its relatively good strength to weight ratio and the obvious aesthetic benefits of its use in buildings. However due to the sensitivity of glass to thermal shock and the considerably temperature-dependent behaviour of interlayer materials as a result of their visco-elastic nature, the mechanical behaviour of laminated glass will be severely influenced by exposure to fire. Relatively little research has been conducted in the past to study the response of load bearing structural glass, and laminated glass in particular to radiant heating. This paper represents an effort to try to understand the effects of through depth radiation absorption and temperature conduction through laminated glass with a view to ultimately developing a model for studying load bearing glass exposed to elevated temperatures, such as those that would be expected in a fire. The paper reports on an experimental research programme in which several monolithic and laminated glass configurations were exposed to a radiant heat flux to study the different phenomena that occur upon exposure to fire conditions, including the ratios of absorbed, transmitted and reflected heat flux to the incident heat flux. The paper then presents a numerical heat transfer model which is developed based on these experimental results and that is able to determine the evolution of the temperature profile as a result of a given incident heat flux. The effectiveness of the heat transfer model is demonstrated through comparison with the temperatures measured during the experimental work.
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| 21. |
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| 22. |
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| 23. |
- Honfi, Daniel, et al.
(författare)
-
A practical approach for supporting decisions in bridge condition assessment and monitoring
- 2019
-
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
-
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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| 24. |
- Honfi, Daniel, et al.
(författare)
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Behavior of load-bearing glass at elevated temperature
- 2018
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Ingår i: ce/papers. - : Wiley. - 2509-7075. ; 2:5-6, s. 533-540
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT The use of glass as a structural material has increased in the built environment over the last decades. Despite the large number of research projects and studies, it still poses difficulties in structural design. This particularly applies to the behaviour of glass in fire and under elevated temperatures since the available data on temperature dependent mechanical and thermal properties of glass is still limited. This contribution provides a brief overview of material properties of glass at elevated temperature and elaborates on current requirements for the fire safety included in standards.
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| 25. |
- Honfi, Daniel, et al.
(författare)
-
Decision support for bridge condition assessment
- 2017
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Ingår i: SMAR 2017 Proceedings.
-
Konferensbidrag (refereegranskat)abstract
- The paper presents the first steps of the development of a theoretical framework for a rational yet practical decision making process concerning the condition assessment of existing bridges in Sweden. The main focus is on how to choose the appropriate level of enhanced conditions assessment considering aspects of model sophistication, uncertainty consideration and knowledge content utilisation. A conceptual case study is presented exemplifying how the framework can be used to structure the assessment actions of a steel bridge subjected to fatigue deterioration.
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| 26. |
- Honfi, Daniel, et al.
(författare)
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Decision support for maintenance and upgrading of existing bridges
- 2017
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Ingår i: IABSE Conference, Vancouver 2017. - : International Association for Bridge and Structural Engineering (IABSE). - 9783857481536 ; , s. 336-345, s. 336-345
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Konferensbidrag (refereegranskat)abstract
- Maintenance of transportation infrastructure assets can be relatively expensive, since it does not only include the direct cost of interventions, but also the indirect consequences of traffic disruptions. To make optimal decisions about maintenance actions, including rehabilitation and upgrading, reliable information about the performance of existing structures is needed. However, obtaining such information might require significant efforts and can be done in various ways. The purpose of an ongoing Swedish research project BIG BRO is to develop a framework for a decision support methodology that can be used for implementing maintenance strategies for bridges on a rational basis. The present paper provides a brief overview about the project as well as describes some of the ongoing work.
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| 27. |
- Honfi, Daniel, et al.
(författare)
-
Inspection and monitoring of bridges in Sweden
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report provides an overview about recent research activities and current practice concerning inspection and monitoring of the structural performance of bridges and the related decision-making process. A brief review of common methods of collecting information on structural performance of bridges is presented, followed by a description of the use of the information collected in structural analysis and maintenance planning. An overview about the state of the art is given including recent scientific developments. Finally, the current Swedish practice for bridge management is presented.
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| 28. |
- Honfi, Daniel, et al.
(författare)
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On the contribution of technological concepts to the resilience of bridges as critical infrastructure assets
- 2016
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Ingår i: IABSE Congress Stockholm 2016. - 9783857481444 ; , s. 975-982
-
Konferensbidrag (refereegranskat)abstract
- The current paper reports about the progress in the ongoing European project IMPROVER (Improved risk evaluation and implementation of resilience concepts to critical infrastructure), in which a fundamental part is devoted to technological resilience concepts. Within the project a general methodology for resilience evaluation is developed, in which existing concepts in the field of structural engineering are aligned with non-technological domains (e.g. organizational and societal) contributing to resilience. A shift from protection to enhancing resilience leads to a shift in focus from traditional risk management towards crisis management. Some of these issues are exemplified here with the application on bridges as critical infrastructures.
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| 29. |
- Honfi, Daniel
(författare)
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Practical considerations in utilizing structural health information in bridge maintenance
- 2019
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Ingår i: Structural Health Monitoring 2019. - : DEStech Publications Inc.. - 9781605956015 ; , s. 1533-1540
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Konferensbidrag (refereegranskat)abstract
- The paper presents two illustrative examples about the utilization of structural health information for rational decision making in everyday bridge management. It is suggested that Bayesian decision analysis could be useful even in sample cases to help efficiently use specific and generic information about structural condition. However, there are some challenges concerning practical application.
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| 30. |
- Honfi, Daniel, et al.
(författare)
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Rational maintenance of timber bridges
- 2017
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Ingår i: Conference proceedings, ICTB 2017. 3rd International Conference on Timber Bridges.
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Konferensbidrag (refereegranskat)abstract
- The present paper provides some ideas about how decisions concerning maintenance of timber bridges should be made in a rational way. First, a brief discussion is provided concerning the evolution of maintenance strategies in general and it is suggested that maintenance of timber bridges should follow a risk-based approach. Then the discussion moves on to the condition assessment of timber bridges with a main focus on inspection and monitoring. The use of non-destructive testing methods and structural health monitoring is highlighted with regard to collecting useful information for maintenance decisions. It is argued that the information collected, should be used in a Bayesian decision analysis framework, which is especially useful in quantifying to value of information and thus the worth of various inspection and monitoring alternatives.
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| 31. |
- Honfi, Daniel
(författare)
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Time-variant reliability of timber beams according to Eurocodes considering long-term deflections
- 2019
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Ingår i: Wood Material Science & Engineering. - : Informa UK Limited. - 1748-0272 .- 1748-0280. ; 26:3, s. 167-178
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Tidskriftsartikel (refereegranskat)abstract
- In order to achieve a consistent level of failure probability, structural design codes are optimized using probabilistic methods. This optimization process traditionally focuses on the ultimate limit states (ULS). However, in the design of timber structures the performance of the structural members is often governed by the serviceability limit state (SLS) associated with different load levels than applied in the ULS. The probability of serviceability failure is strongly dependent on the loading sequence and the time-dependent response of timber; therefore, a time-variant probabilistic model is recommended to estimate them properly. This study aims to investigate the time-dependent reliability for long-term deflections of timber office and residential floor beams according to the specifications of the Eurocodes. A simple creep model is used to calculate the deflections and Monte Carlo simulation is carried out to determine the reliability index. It was found that the creep factor and the suggested deflection limits given in Eurocode 5 might not be appropriate to achieve the expected target reliabilities. To obtain a more consistent reliability, more suitable values for the mentioned parameters were suggested. However, the primary aim was to present a framework to determine appropriate deflection limits for structural codes.
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| 32. |
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IMPROVER D2.2 Report of criteria for evaluating resilience
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In the recent years, the focus has moved from critical infrastructure protection to that of resilience. But how do we know whether a critical infrastructure is resilient or not, how can it be evaluated, measured and enhanced? Drawing on, combining and developing the ideas of the existing literature and practices, the current report develops a holistic, easy-to-use and computable methodology to evaluate critical infrastructure resilience, called Critical Infrastructure Resilience Index (CIRI). The methodology is applicable to all types of critical infrastructure, including a possibility to tailor it to the specific needs of different sectors, facilities and hazard scenarios. The proposed methodology is especially suitable for organizational and technological resilience evaluation, but permits including also elements of societal resilience indicators to the evaluations. The methodology is based on four levels of hierarchically organized indicators. Level 1 consists of the phases well known from the so-called crisis management cycle. Under these phases, we find sets of Level 2 rather generic indicators. Thus under level 1 ‘Prevention’, for instance, we may find a Level 2 indicator such as ‘Resilient design’, further divided into Level 3 more detailed indicators such as ‘Physical robustness’, ‘Cyber robustness’, ‘Redundancy’, ‘Modularity’, and ‘Independency’. The task is to study these indicators on Level 4 in the context of concrete critical infrastructure facilities and hazard scenarios, that is, applying Level 3 indicators into concrete circumstances. The methodology then permits to transfer quantitative, semi-quantitative and qualitative evaluations of individual sector-specific resilience indicators into uniform metrics, based on process maturity levels. This in turn makes it possible to give a specific critical infrastructure, or its part, a resilience value on the scale 0-5. While the real resilience value becomes clear only when one engages in the analysis of several indicators, the methodology can be used also as a step-by-step measurement and development tool for resilience, without necessary immediately engaging in time-consuming total resilience analysis. The user of this methodology is supposed to be the operator of critical infrastructure, or part of it, in the spirit of self-auditing. In case it would be implemented in a wider scale, in cooperation between the operators and authorities, it would give the authorities a holistic picture about the respective society’s critical infrastructure resilience. In this report, we draw a concise picture of the methodology and illustrate how this methodology could be applied to a specific infrastructure and hazard scenario.
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| 33. |
- Ioannou, Ioanna, et al.
(författare)
-
IMPROVER D2.1 Methodology for identifying hazard scenarios to assess the resilience of critical infrastructure
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Critical infrastructure is exposed to a wide range of hazards, capable to disrupt its operations in various degrees. This raises the question of which hazard scenario an operator shall use to assess the resilience of their critical infrastructure asset. Various techniques aiming to prioritize the various risks are commonly used in the literature. This study proposed an 8-step methodology, which aims to rank the risks of pre-defined hazard scenarios by eliciting the opinions of the stakeholders through a structured expert elicitation technique termed paired comparison. The novelty of the proposed technique is its ability to quantify the degree of disagreement regarding the ranking order of the scenarios and thus to capture the uncertainty associated with these risks. The proposed methodology has been applied to four living labs, namely: the Oresund region, the port of Oslo, the A31 Highway in France and the potable water network in Barreiro. The applications aims to rank scenarios of natural and operational hazards according to their disaster- and emergency-risk. Despite the small number of participants, the results provide an excellent basis for further discussion regarding the most likely disaster or emergency risk scenarios. For most living labs, the ranking of the hazards using paired comparison was successful in identifying the scenarios associated with the highest risk. Overall, ranking the natural hazards according to their disaster- or emergency-risk has been associated with a higher degree of consensus than the ranking of the operational hazards reflecting on the higher complexity and perhaps the limited understanding of the later. In more detail, snow storm is the hazard with the highest disaster risk for the A31 Highway. Similarly, earthquake is the hazard with the highest disaster risk for the water network in Barreiro. Three meteorological hazards ranked the highest for both the likelihood to occur and to cause disaster to the Øresund region. By contrast, the ranking of the hazards for the port of Oslo identified several scenarios with similar likelihood to cause disaster, which ranked very different in their likelihood to occur in the next 5 years. This raises question as to whether the most of least likely to occur scenarios is most suitable which can be answered in collaboration with the stakeholders. With regard to the operational hazards, the contamination of the water in the water source or the distribution network due to an accident at the high-risk industrial SEVECO operations has been identified as the single scenario with the highest risk of disaster for the water network in Barreiro. Three events including a multiple day strike and two accidents in the wet bulk terminal have been identified as having the highest disaster risk for the port of Oslo. By contrast, no operational hazards can be identified as having the highest risk of occurrence for the A31 highway and the Øresund region
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| 34. |
- Kozlowski, Marcin, et al.
(författare)
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Numerical Analysis and 1D/2D Sensitivity Study for Monolithic and Laminated Structural Glass Elements under Thermal Exposure
- 2018
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- Glass is largely used in architectural and engineering applications (i.e., buildings and vehicles) as a structural material, especially in the form of laminated glass (LG) sections. To achieve adequate and controlled safety levels in these applications, the well-known temperature-dependent behavior of viscoelastic interlayers for LG sections should be properly accounted for during the design process. Furthermore, the materials' thermomechanical degradation with increases of temperature could severely affect the load-bearing performance of glass assemblies. In this context, uncoupled thermomechanical finite element (FE) numerical models could represent a robust tool and support for design engineers. Key input parameters and possible limits of the FE method, however, should be properly calibrated and assessed, so as to enable reliable estimations for the real behavior of glazing systems. In this paper, FE simulations are proposed for monolithic (MG) and LG specimens under radiant heating, based on one-dimensional (1D) and two-dimensional (2D) models. A special attention is focused on thermal effects, being representative of the first step for conventional uncoupled, thermomechanical analyses. Based on experimental results available in the literature, FE parametric studies are discussed, giving evidence of limits and issues due to several modeling assumptions. In particular, careful consideration is paid for various thermal material properties (conductivity, specific heat) and thermal boundaries (conductivity, emissivity), but also for other influencing parameters like the geometrical features of samples (thickness tolerances, cross-sectional properties, etc.), the composition of LG sections (interlayer type, thickness), the loading pattern (heat transfer distribution) and the presence of additional mechanical restraints (i.e., supports of different materials). Comparative FE results are hence critically discussed, highlighting the major effects of such influencing parameters.
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| 35. |
- Kozłowski, Marcin, et al.
(författare)
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Structural considerations on timber-glass composites at fire scenarios
- 2018
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Ingår i: Challenging Glass 6. - : TU Delft Open. - 9789463660440 ; , s. 229-240
-
Konferensbidrag (refereegranskat)abstract
- This paper focuses on a recently developed concept, in which glass is combined with timber to provide post-breakage strength and ductility. This combination allows for good post-breakage performance and overall robustness of timber-glass composite beams and wall elements, which has been reported in several publications. The application of timber-glass elements in practice, however, raises important issues related to structural fire performance. The paper elaborates on this issue and provides general information about the behavior of glass, timber and adhesives at elevated temperatures and under fire conditions. Furthermore, it presents ideas and strategies developed for potential application of timber-glass composites in practical situations. The paper presents also initial results from an on-going research project on fire performance of timber-glass composites Copyright © with the authors. All rights reserved.
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| 36. |
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| 37. |
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| 38. |
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| 39. |
- Lange, David, et al.
(författare)
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Incorporation of resilience assessment in critical infrastructure risk assessment frameworks
- 2017
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Ingår i: Safety and Reliability - Theory and Applications - Proceedings of the 27th European Safety and Reliability Conference, ESREL 2017. - CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 : CRC Press/Balkema. - 9781138629370 ; , s. 1031-1038
-
Konferensbidrag (refereegranskat)abstract
- This paper explores the concept of Critical Infrastructure (CI) resilience and its relationship with current Risk Assessment (RA) processes. It proposes a framework for resilience assessment of CI, which integrates the resilience paradigm into the RA process according to ISO 31000. The framework consists of three levels, namely (a) asset (focus on individual CI assets), (b) system (focus on dependencies between CI assets) and (c) national or regional (focus on societal aspects). It is applicable to individual CI or their combinations, accounting both for existing RA processes, for interdependencies and their effect on interconnected CI, while at the same time employing current, available resilience analysis tools and methodologies. This approach is also compatible with the current European guidelines for national RA applied by the EU Member States. © 2017 Taylor & Francis Group, London.
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| 40. |
- Lange, David, et al.
(författare)
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Novel techniques and approaches for risk based application of resilience concepts to critical infrastructure : An introduction to the IMPROVER project
- 2017
-
Ingår i: Risk, Reliability and Safety. - Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742 : CRC Press. - 9781138029972 ; , s. 2168-
-
Konferensbidrag (refereegranskat)abstract
- The impact of disasters and crises in Europe is char-acterised by a highly interconnected society–a society which is increasingly reliant on critical infrastructures providing services which are centralised, if not terri-torially then contextually. Through cascading failures through interdependent systems the indirect consequences of natural and man-made disasters may be more severe than expected.
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| 41. |
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| 42. |
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| 43. |
- Larsson Ivanov, Oskar, et al.
(författare)
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Consideration of uncertainties in LCA for infrastructure using probabilistic methods
- 2019
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Ingår i: Structure and Infrastructure Engineering. - : Informa UK Limited. - 1573-2479 .- 1744-8980. ; 15:6, s. 711-724
-
Tidskriftsartikel (refereegranskat)abstract
- The construction and usage of transport infrastructure are major causes of greenhouse gas emissions and energy consumption. The effects of resource consumption and pollutant emissions are often quantified through Life Cycle Assessment (LCA) models. All decisions made in infrastructure projects during the whole life cycle are afflicted by uncertainty, e.g. physical properties of materials or amount of pollutants emitted by certain processes. The pervasive role of uncertainty is reflected in LCA models, which therefore should consider uncertainty from various sources and provide a sound quantification of their effects. The aim of the work presented in this paper is to give an overview of different sources of uncertainty in LCA of infrastructure projects and to describe systematic methods to evaluate their influence on the results. The possibility of including uncertainty in a LCA-tool for infrastructure is presented, studying the sensitivity of the model output to the input parameters and two alternative approaches for propagation of uncertainty using two case studies. It is shown that, besides the influence of uncertainty in emission factors, other inputs such as material amounts and service life could contribute significantly to the variability of model output and has to be considered if reliable results are sought.
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| 44. |
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| 45. |
- Larsson Ivanov, Oskar, et al.
(författare)
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Prolca—treatment of uncertainty in infrastructure LCA
- 2019
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Ingår i: Life-Cycle Analysis and Assessment in Civil Engineering. - : CRC Press/Balkema. - 9781138626331 - 9781351857574 ; , s. 2923-2930
-
Konferensbidrag (refereegranskat)abstract
- The construction, operation and maintenance of transportation infrastructure require energy and materials which impact the environment. Large infrastructure projects thus use resources intensively and leave a significant environmental footprint. To demonstrate and support the sustainability of such large-scale projects, life cycle assessment (LCA) has become a common tool to evaluate environmental impacts in all stages of infrastructure life cycle, from raw material production through end-of-life management. However, the various phases of the assessment are all associated with uncertainties. If decisions are made without consideration of these uncertainties, they might be misleading and suboptimal. In this paper, results are presentedwhere variations associated with different parameters and tools for life cycle assessment have been considered using probabilistic methods. A categorization of common uncertainties in LCA is also included. The most influential parameters can be identified with sensitivity analysis methods, since for LCA with a large number of parameters it may be unreasonable to incorporate all in a probabilistic simulation. For a limited amount of influential variables, Monte Carlo simulation has been used to assess the effects of uncertainties on the results.A bridge has been used as a case study to find important aspects in infrastructure LCA. The results indicate that if the most influential parameters are considered as random variables, it is possible to estimate the uncertainty and increase the validity of the life cycle assessment.
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| 46. |
- Larsson Ivanov, Oskar, et al.
(författare)
-
Uncertainty and variation in LCA - Implementation of probabilistic methods to assess environmental impacts of infrastructures
- 2018
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- For most applications trying to interpret the real world uncertainties will be an important factor to consider, which is also true for Life-Cycle Assessment used for estimating total environmental impact during the life-cycle of products, services, buildings, structures, roads etc. The construction and usage of infrastructure are major causes of emissions and energy use, thus making it even more important for society to aim at reducing this impact. One way of reducing environmental impact is by using LCA to show improvements for specific items and/or benefits of using a specific solution over another. To be able to use LCA, or any other calculated estimation, for comparisons it is of great importance to incorporate effects of uncertainties and to understand where such uncertainties have their sources. Otherwise, any attempt on comparing two solutions will be flawed and there is a risk for bias towards a specific solution. The aim of the work presented in this report have been to describe and discuss the types of uncertainties present in a LCA, and to discuss their importance, source and influence. An extensive review of the current state of the art of both uncertainties in general and specifically for LCA have been performed to find the most common ways of including uncertainties in LCA, with focus on the possibilities and limitations of different types of methods. It was found that many previous attempts on including uncertainties in LCA exists, and they showed that it is now possible to using probabilistic methods such as Monte Carlo simulations to incorporate uncertainties in LCA-tools, since the computational capacity have increased. The common problem for all previous studies and the study presented here is the availability of validated input data including uncertainty estimations. Initiatives exist for data quality control; however, they do not fully consider the effect of uncertainties, and typically have been limited to the consideration of variations in emission factors only. Other factors such as system boundaries and choices made by the user have a much larger influence on the result than a small variation in the emission factor itself.To evaluate this, the basis for a methodology considering uncertainties in LCA and possibilities for controlling these uncertainties is presented. The methodology is based on general definitions of uncertainties to be able to understand the source and characteristics of each affecting parameter and for making informed decisions on how to reduce the uncertainty depending on the purpose of the LCA. This kind of methodology will especially be valuable for raising awareness of uncertainties in LCA for different stages of the building process.The possibility of including uncertainties in a LCA-tool for infrastructures in also presented, showing possibilities for studying the sensitivity of the input parameters and the propagation of uncertainties. A case study is used to demonstrate these possibilities, showing the importance of considering uncertainties in all input parameters. It is shown that the influence of other factors apart from the emission factors can be large, such as material amounts and expected service life, and that they have to be considered if reasonable results are sought. It should be noted, however, that the case study presented in this report serves illustrative purposes and includes significant simplifications.
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| 47. |
- Larsson, Oskar, et al.
(författare)
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A probabilistic approach for handling uncertainty in infrastructure LCA
- 2016
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Ingår i: IABSE Congress Stockholm 2016. - 9783857481444 ; , s. 1677-1685
-
Konferensbidrag (refereegranskat)abstract
- To demonstrate and support sustainability of large-scale infrastructure projects, life cycle assessment (LCA) has become a common tool used in the evaluation of environmental impact. However, LCA includes a number of phases, which are all associated with uncertainties. Decisions made without regard to these uncertainties may be suboptimal and/or misleading. The current paper discusses some important issues about how to deal with uncertainties in LCA. Two case studies are presented that shows the effect of including uncertainty in various parameters. The results show that a reduction in uncertainty due to manufacturing improvements can increase the reliability of the results significantly. It was also found that the uncertainty assumptions for parameters where data is not available have a large impact on the LCA-results.
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| 48. |
- Leander, John, et al.
(författare)
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A decision support framework for fatigue assessment of steel bridges
- 2018
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Ingår i: Engineering Failure Analysis. - : Elsevier BV. - 1350-6307 .- 1873-1961. ; 91, s. 306-314
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Tidskriftsartikel (refereegranskat)abstract
- Many bridges are approaching or have already passed their expected service life. For steel bridges, fatigue is often the decisive degradation phenomenon that theoretically puts restrictions on a continued use. At the same time, fatigue is also afflicted with large uncertainties on the resistance side as well as on the action effect side. An accurate assessment of the service life will require measures outside the governing regulations but understanding what steps to take and how to consider the outcome for decisions on interventions can be a difficult task for a non-expert. This paper presents possible assessment actions and a decision support framework for rational decisions on interventions to extend the theoretical service life of existing bridges. A case study of a critical railway bridge is incorporated to demonstrate the framework. The aim is to provide a tool for bridge managers on how to evaluate and procure different assessment actions.
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| 49. |
- Leander, John, et al.
(författare)
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Risk-based planning of assessment actions for fatigue life prediction
- 2017
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Ingår i: 2nd International Conference on Structural Integrity, ICSI 2017, 4-7 September 2017, Funchal, Madeira, Portugal. - : Elsevier. ; 5, s. 1221-1228
-
Konferensbidrag (refereegranskat)abstract
- It is vital to extend the service life of existing bridges as far as possible as a means for improved sustainability leading to reduced economic cost and resource consumption. This requirement is especially valid for bridges which are critical components of highly vulnerable infrastructure systems. Achieving this aim requires enhanced methods involving various actions and methods influencing different aspects of the assessment process. A framework is presented in this paper based on three common factors used to describe the assessment actions of existing bridges; (i) model sophistication, (ii) uncertainty consideration, and (iii) knowledge content. The framework elucidates the influence of different decisions on the assessment process and facilitates the planning of appropriate assessment actions. Furthermore, it provides a basic scheme for a risk-based decision analysis for determining suitable assessment actions or activities. A fatigue assessment of an existing bridge detail is used to demonstrate the application of the framework in practical cases.
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| 50. |
- Lenk, Peter, et al.
(författare)
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Resilience, Damage Tolerance & Risk Analysis of a Structure Comprising Structural Glass
- 2016
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Ingår i: Engineered Transparency 2016. - 9783433031872 ; , s. 639-646
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- With increased popularity of structural glass applications, questions about structural safety and risk associated with such applications to the general public shall be examined in detail. Often these types of applications are used in public or semi-public spaces thus they receive increased attention and the consequences of failure or underperformance are crucial. Further, a comprehensive, standardised methodology of designing glass structurally is still lacking. In this paper we will review resilient con-cepts currently adopted by engineers designing with structural glass to ensure that structural reliability and robustness criteria are met. This is especially challenging, since a well-established probabilistic basis, that is (at least partly) available for traditional construction materials, has not yet been devel-oped for structural glass. To ensure the consideration of a system and life-cycle perspective, opera-tional objectives, damage sensitivity and damage tolerance for possible load exposures during the design lifetime will be outlined.
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