1,720,992 research outputs found
Bærekraftig bygging - En sammenligning av klimagassutslipp fra bæresystem i betong og massivtre
Get PDFByggebransjen står i dag for en tredjedel av klimagassutslippet. Innen 2030 skal klimagassene reduseres med 40%. Byggebransjen er i stadig endring og utvikling. For å konkurrere om oppdragene er det nødvendig å holde seg oppdatert på hvordan man på best måte bygger mest mulig miljøriktig. Målet med denne oppgaven er å kunne opplyse utbyggere om miljøkonsekvensene ved valg av bæresystem.
Denne oppgaven er et samarbeid med Sweco Norge AS og skal svare på problemstillingen: Hvilket av materialene, betong eller tre, vil medføre lavest klimagassutslipp?
Oppgaven tar for seg ett bygg i hhv. betongelementer og massivteelementer. Betongelementbygget er et eksisterende prosjekt og er utgangspunktet for utformingen av bygget i massivtreelementer. For å regne på klimagassutslippet er det gjort en livsløpsanalyse av begge byggene og resultatene har blitt sammenlignet. I denne oppgaven er det konkludert med at bruk av massivtre vil være et bedre valg enn betong. Likevel er det verdt å nevne at størrelse, utforming og plassering kan påvirke resultatet
Critical chloride content in reinforced concrete. COIN workshop, 5-6 June 2008, Trondheim, Norway. P4 «Operational service lifte design»
Get PDFCritical chloride content in reinforced concrete. COIN workshop, 5-6 June 2008, Trondheim, Norway. P4 «Operational service lifte design»
No full textAbaqus FEA with Concrete Damaged Plasticity and its feasibility in recreating laboratory experiments: A numerical analysis and sensitivity study
Get PDFNon-linear Finite Element Analysis of concrete is a subject that is constantly worked on. Due to the complex nature of concrete, both in pure states and when reinforced, there are many different models and approaches when it comes to representing the material digitally. A range of systems exist with an even greater range of different theoretical models implemented in an attempt to replicate, predict, and analyse the behaviour of concrete structures.
One such piece of software is Abaqus FEA, which has the concrete model Concrete Damaged Plasticity as part of its base package. This plasticity model is widely used in order to model concrete, and like other material models it requires a range of different material input parameters to be defined correctly – otherwise accurate results cannot be expected to be achieved.
This thesis aims to investigate the material parameter inputs required by Concrete Damaged Plasticity in Abaqus FEA, utilising material data taken from a previously completed experiment which presents its findings in a doctorate, performed and written by Professor Gro Markeset.
By extracting data from Markeset’s research, adjusting it according to Concrete Damaged Plasticity theory, and carefully investigating the impact of changing each base parameter, the authors have made an attempt at identifying the parameter values that allows for recreation of the laboratory experiment in the Finite Element Software.
Following this, the thesis looks at the feasibility of extracting the identified parameters and combining them with uniaxial stress-strain data in order to mimic an experimental 4-point bending test of reinforced concrete beams. The research performed by the authors of this thesis covers a wide field of necessary considerations related to this type of work. Lastly, suggestions on how to further this work and increase both accuracy and potential are presented.publishedVersio
Automatic BIM-model creation of bridge structure using 3D-laser scanning, algorithms and parametric modeling
No full textBridges have a crucial and huge role in the safety of the public. An important aspect in maintaining the safety of a bridge structure is to have access to a BIM-model that can be used in analysis and facility management. Long-span spatial curved bridge structures with circular pipe components are widely used in engineering. Measuring the overall alignment of long-span spatial curved structures with circular pipe components quickly and accurately is an important aspect that increase the effectiveness of creating digital twins. This thesis has an approach to find a method to measure this overall alignment in an accurate and quick way.
The method in this thesis is applied to a real case study which is a pedestrian bridge located in Oslo, Norway. The bridge consists of curved steel members at top chord and circular pipe components as struts.
The method implements terrestrial 3D laser scanning of the case bridge for data collection. The data obtained from the scans has been processed and imported into MATLAB to extract geometry information of the components automatically by applying algorithms. The information and parameters extracted from MATLAB are then imported into Dynamo to generate a parametric driven BIM-model of the existing bridge. The model is compared with the point cloud of the bridge to analyze the deviation between the point cloud and the parametric driven BIM-model.
The results obtained from various operations have a good level of accuracy, but there are still room for adjustments in the method that can improve the accuracy of the results. The case study examination in this thesis was however successful, and it can be concluded that the method applied in this thesis can help to measure the overall alignment of long-span curved structures with circular pipe components quickly and accurately
Non-Destructive Testing and Machine Learning in Inspection of Post-Tensioned Concrete Bridges
Get PDFBridges are critical infrastructures essential for transportation and economic activities yet face accelerated deterioration from environmental factors and increased usage. Post- tensioned concrete bridges offer potential solutions but recent failures underscore deficiencies in inspection protocols. In Norway, where harsh climates and marine environments exacerbate deterioration, effective Non-Destructive Testing (NDT) methods are crucial.
This thesis explores the integration of Machine Learning (ML) with NDT techniques for post-tensioned bridge inspection. Mock-up testing revealed significant variability among NDT devices, emphasizing the need for expert interpretation. Training ML models, including the Roboflow model, demonstrated initial efficacy but highlighted the ongoing need for fine- tuning and optimal dataset distribution.
Model testing across various scenarios showed the Roboflow model's superiority in detecting structural features such as ducts and rebars, albeit with challenges in distinguishing subtle features. Custom models also showed potential, emphasizing the need for further refinement and adaptation to real-world conditions.
In conclusion, effective real-time detection of structural features in post-tensioned bridges requires advanced ML models integrated with expert NDT interpretation. While promising, ongoing optimization and validation against real-world datasets are essential. This research contributes to enhancing inspection protocols, aiming to improve infrastructure safety and longevity in civil engineering practices.
Keywords: Non-destructive testing, Machine Learning, Post-tensioned Concrete, Roboflow, Custom Model
Control of the curing process for hybrid concrete in post-tensioned slabs
Get PDFThrough the computer-based curing technology program CrackTeSt COIN, the thesis has made measurements of two concrete compositions with high pozzolan dosage, respectively 50% and 65% of the total effective binder. The task is related to Skanska's project Gullhaug Torg 2A, designed with post-tensioned slabs, where the mentioned concrete will be used. Due to the tensioning of compressive forces and the project's progress, the slabs must achieve a compressive strength of 25 MPa within 3 days. This has led to the thesis dealing with the concrete's development of mechanical properties in the form of temperature and compressive strength. This study has shown that the environmental ambitions regarding concrete are possible but that it entails challenges due to the concrete's low heat development and relatively slow strength development. At minus degrees, it is imperative to control the curing process with the correct use of measures and possibly use the concrete with the lowest amount of pozzolans. The pozzolan reaction proceeds slowly at low temperatures and rapidly at high temperatures. The results have shown that progress can be accelerated at high temperatures as the required strength is well within the 3-day requirement.publishedVersio
Automatic BIM-model creation of bridge structure using 3D-laser scanning, algorithms and parametric modeling
Get PDFBridges have a crucial and huge role in the safety of the public. An important aspect in maintaining the safety of a bridge structure is to have access to a BIM-model that can be used in analysis and facility management. Long-span spatial curved bridge structures with circular pipe components are widely used in engineering. Measuring the overall alignment of long-span spatial curved structures with circular pipe components quickly and accurately is an important aspect that increase the effectiveness of creating digital twins. This thesis has an approach to find a method to measure this overall alignment in an accurate and quick way.
The method in this thesis is applied to a real case study which is a pedestrian bridge located in Oslo, Norway. The bridge consists of curved steel members at top chord and circular pipe components as struts.
The method implements terrestrial 3D laser scanning of the case bridge for data collection. The data obtained from the scans has been processed and imported into MATLAB to extract geometry information of the components automatically by applying algorithms. The information and parameters extracted from MATLAB are then imported into Dynamo to generate a parametric driven BIM-model of the existing bridge. The model is compared with the point cloud of the bridge to analyze the deviation between the point cloud and the parametric driven BIM-model.
The results obtained from various operations have a good level of accuracy, but there are still room for adjustments in the method that can improve the accuracy of the results. The case study examination in this thesis was however successful, and it can be concluded that the method applied in this thesis can help to measure the overall alignment of long-span curved structures with circular pipe components quickly and accurately.publishedVersio
Reducing global warming impact for Kjøkøysund based on alternative bridge designs
Get PDFConcrete manufacturing account for almost one tenth of the global CO2- emissions. A big portion of the concrete greenhouse gas emission comes from the production of cement, still concrete is the most used construction material in the world. New types of concrete have been and are under development in order to reduce their global warming impact. One of the new concrete types is low carbon concretes. These types of concrete have been utilized widely in the building industry but is absent in larger bridge constructions.
The main goal for this thesis is to investigate the possibilities for material and design change of Kjøkøysund bridge, with the goal to reduce the global warming impact. Kjøkøysund bridge is a concrete cantilever bridge, which connects Kråkerøy and Kjøkøy. There has been done a condition assessment on the bridge, and the conclusion of this work is to tear the existing bridge and construct a new one next to it. The report from Statens Vegvesen “Bærekraftige betongkonstruksjoner” has been used to investigate the possibilities to optimize and reduce the greenhouse gas emissions for concrete bridges. Some of the possible solutions in the report is to change materials or superstructure design.
In this thesis the research question has been approached by conducting a literature study. The gathered information has been employed on the case study ‘’ Material and design change on Kjøkøysund bridge’’. Various designs with different materials and superstructures have been investigated for an alternative solution for Kjøkøysund bridge. EPD from different concrete and steel supplier have been collected and used in a calculation to find most environmentally friendly material. For the transportation stage A4, the transport calculator provided by Østfoldforskning have been used. To verify these results a life cycle assessment with the software One Click LCA have been conducted, with several other bridge designs which was considered to be suitable for Kjøkøysund bridge.
Regarding global warming impact for Kjøkøysund bridge, alternative bridge solutions have been presented in this thesis. Since this thesis have a broad approach and not focused on one specific solutions, further research must be conducted.publishedVersio
Structural analysis of reinforced concrete beams affected by alkali-silica reaction with focus on material models for concrete
Get PDFMaster i bygg og- konstruksjonsteknikk - sivilingeniørAlkali-silica reaction (ASR) is a chemical reaction that occurs in concrete between the alkalized cement and silica within the aggregates. ASR produces a gel around the aggregates which absorbs water, expands, results in local stresses, and causes the concrete to crack internally and externally. Research on this chemical reaction and development of concrete models including this reaction has been extensive. However, limited research about the structural effects of ASR and load actions due to ASR has been carried out. Due to lack of applicable constitutive models including the effect of ASR in finite element softwares, simplified methods for the assessment of ASR damaged reinforced concrete structures are used.
In this master thesis structural analyses of reinforced concrete beams affected by ASR have been carried out. Analyses on one span- and three span beams have been carried out to study the effect of using more complex concrete material models which includes the stress dependency of the ASR expansion and the stiffness reduction due to ASR. The load actions due to ASR with different concrete material models are computed and compared. From the case studies it was found that the non-unifrom ASR expansion and the stress dependency of the ASR expansion had significant impact on the load actions.publishedVersio
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