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Journey to Sustainability: Small Regions, Sustainable Carrying Capacity and Sustainability Assessment MethodsGraymore, Michelle, n/a January 2005 (has links)
Small region sustainability is an extremely important part of the journey to sustainability of the global population, as the most difference can be made at this spatial level through decision making and community choice. However, small regions have not been the focus of sustainability literature. Therefore, this thesis develops theory to explain what small region sustainability involves and tested the applicability of current sustainability assessment methods to find an effective tool for the journey to sustainability that can be used for social learning, decision making, policy development, research and monitoring of sustainability in small regions. It was found through the development of a model of sustainable carrying capacity and the major pressures of human activities on the environment, that sustainability for small regions means living equitably with the impacts of human activities in the region within the limits of its ecosystems. This thesis also found that none of the current sustainability methods tested were effective or useful as a tool for small regions. Therefore, a new sustainability assessment method was developed, the Sustainable Carrying Capacity Assessment (SCCA), which assesses the equitability and size of the major pressures that the human activities are causing and determines if this pressure exceeds the sustainable carrying capacity of the region, and thus, the sustainability of the population. Thus, for small regions to become sustainable, they must live equitably within the sustainable carrying capacity of the region's ecosystems, and a tool that can help them achieve this is the SCCA. By raising social awareness, guiding policy development and decision making this method can help guide small regions, and other spatial levels on their journey to sustainability. Therefore, it is recommended that Local Government Areas, Regional Organisation of Councils, schools, local community groups and anyone who wants to learn more about sustainability use this method. This thesis, therefore, makes a significant contribution to the field of sustainability.
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Posouzení existující železobetonové konstrukce / Assessment of existing reinforced concrete structuresPospíšil, Ondřej January 2014 (has links)
This master’s thesis is concerned with the static load capacity assessment of the reinforced concrete facility in the sports and recreational compound Kraví Hora in Brno, which is up to be reconstructed. The calculation results, overall assessment and static security suggestions are interpreted in the summary of the thesis.
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Nonlinear FEM load bearing capacity assessment of a concrete bridge subjected to support settlements : Case of a continious slab bridge with angled supportsHansson, Daniel January 2013 (has links)
A nonlinear finite element analysis was performed for an existing road bridge in order to see if that could show a higher load bearing capacity, as an alternative to repairing or replacing. The regular linear analysis had shown that the bridge could not take any traffic load due to the effects from large and uneven support settlements. It is a five-span reinforced concrete bridge with a continuous slab on supports made out of rows of columns. The width-to-span ratio was around 1 and the supports were angled up to about 30°, giving rise to a complex three-dimensional behaviour, which was seen and studied in the nonlinear results. Since the bending moment was the limiting factor, the nonlinear analysis focused on that. The direct result was that the load bearing capacity was 730 kN for the traffic vehicle boogie load, B, in the ultimate limit state. This was however only for the load case tested, and several more disadvantageous vehicle positions may exist. Other aspects also became limiting, as the maximum allowed vertical deflection in the serviceability limit state was reached at 457 kN. The most restraining though, was the shear capacity from the linear analysis; 78 kN, since it was not possible to simulate that type of failure with the shell elements used in the nonlinear finite element analysis. The main aim of the thesis was nonetheless reached, since the nonlinear analysis was able to show a significant increase in load bearing capacity. A comparison was made with the settlements for the nonlinear case, to see how much influence they had on the load bearing capacity for traffic load. This was performed for both the bridge and a simple two-span beam. Both showed that there was no effect on the load bearing capacity in the ultimate limit. One thing to note was that the full settlements were applied, and with no relaxation due to creep. Another aim of the thesis was to make comments on the practical usability of the nonlinear finite element method in load bearing capacity assessments. A linear analysis was performed before the nonlinear in order to be able to determine the load case to be used in the latter. This worked well, as the strengths of the two methods could then be utilized. Convergence problems were however encountered for the nonlinear when using the regular static solver. Due to this, the dynamic explicit calculation scheme was used instead, treating the case as quasi-static. This managed to produce enough usable results. It was concluded that the nonlinear finite element method is useable for assessment calculations, but that its strengths and weaknesses must be known in order to make it an efficient method.
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Capacity assessment of a single span arch bridge with backfill : A case study of the Glomman BridgeBjurström, Henrik, Lasell, Johan January 2009 (has links)
No description available.
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Nonlinear FEM load bearing capacity of a concrete bridge subjected to support settlements : Case of a continuous slab bridge with angled supportsHansson, Daniel January 2013 (has links)
A nonlinear finite element analysis was performed for an existing road bridge in order to see if that could show a higher load bearing capacity, as an alternative to repairing or replacing. The regular linear analysis had shown that the bridge could not take any traffic load due to the effects from large and uneven support settlements. It is a five-span reinforced concrete bridge with a continuous slab on supports made out of rows of columns. The width-to-span ratio was around 1 and the supports were angled up to about 30°, giving rise to a complex three-dimensional behaviour, which was seen and studied in the nonlinear results. Since the bending moment was the limiting factor, the nonlinear analysis focused on that. The direct result was that the load bearing capacity was 730 kN for the traffic vehicle boogie load, B, in the ultimate limit state. This was however only for the load case tested, and several more disadvantageous vehicle positions may exist. Other aspects also became limiting, as the maximum allowed vertical deflection in the serviceability limit state was reached at 457 kN. The most restraining though, was the shear capacity from the linear analysis; 78 kN, since it was not possible to simulate that type of failure with the shell elements used in the nonlinear finite element analysis. The main aim of the thesis was nonetheless reached, since the nonlinear analysis was able to show a significant increase in load bearing capacity. A comparison was made with the settlements for the nonlinear case, to see how much influence they had on the load bearing capacity for traffic load. This was performed for both the bridge and a simple two-span beam. Both showed that there was no effect on the load bearing capacity in the ultimate limit. One thing to note was that the full settlements were applied, and with no relaxation due to creep. Another aim of the thesis was to make comments on the practical usability of the nonlinear finite element method in load bearing capacity assessments. A linear analysis was performed before the nonlinear in order to be able to determine the load case to be used in the latter. This worked well, as the strengths of the two methods could then be utilized. Convergence problems were however encountered for the nonlinear when using the regular static solver. Due to this, the dynamic explicit calculation scheme was used instead, treating the case as quasi-static. This managed to produce enough usable results. It was concluded that the nonlinear finite element method is useable for assessment calculations, but that its strengths and weaknesses must be known in order to make it an efficient method.
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Capacity assessment of a single span arch bridge with backfill : A case study of the Glomman BridgeBjurström, Henrik, Lasell, Johan January 2009 (has links)
<p> </p><p>The aim of this Master Thesis is to assess the load carrying capacity of the Glomman Bridge outside of the Swedish city Örebro. The Glomman Bridge is an unreinforced concrete single span arch bridge with backfill. The bridge was constructed in 1923 on assignment from the Swedish National Railways (SJ).</p><p>The failure criteria used in this thesis is that the bridge collapses when any cross section in the concrete arch reaches its ultimate capacity. In reality, the bridge may manage heavier loads than this. When the capacity is reached in a cross section, a hinge is formed and the arch relocates the forces to other parts of the arch that can carry higher stresses. The real bridge will not collapse until a fourth hinge is formed, and by that a mechanism. To be able to calculate the cross section forces in the arch, it was necessary to know the influences of the loads on the arch when they were run along the bridge. For this purpose, influence lines were obtained from a 2D finite element model created in ABAQUS, a general FE-analyses software. A calculation routine to find the least favourable load combination was then created in Matlab, a numerical calculation software. The routine was made to find the worst case among different load cases and to combine the standardized axle pressures with the present number of axles.</p><p>A parametric survey was also performed because the material properties for the different parts of the bridge are very uncertain. In the survey, the initial values were changed one at a time to study the outcome on the load factor. The load factor is the ratio between the ultimate limit load and the actual load. The studied parameters are the compressive strength, the Young's modulus, the density and the Poisson's ratio of the different parts of the bridge. The parameters are studied individually irrespective of possible correlation. The studied parts of the bridge are the backfill, the arch, the abutments and the asphalt. The clearly most important component is found to be the backfill. With increased stiffness or increased Poisson's ratio in the backfill follows increased load factor.</p><p>The equations behind the failure envelope can be derived from equilibrium equations for the unreinforced cross section. The influence lines are normalised with respect to the capacity of the cross section to get the degree of efficiency along the whole length of the arch, instead of the common influence lines that give the cross section forces. This is done because the failure is not caused by large cross section forces but by an exceeded ultimate stress. As the different loads are run along the bridge, the largest positive and negative efficiency for bending moment and normal force are localised. The normalised cross section forces are plotted together with the failure envelope and the load factor is then calculated.</p><p>Several masonry arch bridges were loaded until collapse in a study performed by the British Transport and Road Research Laboratory. One of the bridges in the study, the Prestwood Bridge, has been used in this thesis as a comparison to the Glomman Bridge. The load carrying capacity of the Prestwood Bridge is known, and is used to verify that the method using the failure envelope is applicable.</p><p>To compare the results from the cross section analysis from the failure envelope model to another method, the Glomman Bridge and the Prestwood Bridge were also tested in the commercial software RING 2.0. The method used in RING 2.0 differs from the failure mode in this thesis by calculating the load factor when four different cross sections reach their capacity and the bridge collapses.</p><p>The failure envelope method allows an A/B-value (Axle- and Bogie load) of 102 kN/147 kN when using very poor values of the parameters and 181 kN/226 kN when using a reference case with normal parameters.</p><p>Although the load capacity is found to be acceptable, the uncertainties are still large. To get a more accurate apprehension of the condition of the actual bridge, further research should be carried out, such as e.g. a non-linear model.</p> / <p>Syftet med föreliggande examensarbete är att uppskatta bärförmågan hos bron Glomman utanför Örebro. Glomman är en oarmerad betongvalvbro i ett spann med ovanliggande jordfyllning. Bron byggdes 1926 på uppdrag av Statens Järnvägar (SJ).</p><p>Brottkriteriet i detta examensarbete är att bron går till brott när något tvärsnitt i betongbågen uppnår sin kapacitet. I själva verket är det möjligt att bron kan klara tyngre last än detta. När kapaciteten nås i ett tvärsnitt uppstår en led och bågen omlagrar krafterna till andra bågdelar som klarar större spänningar. Den verkliga bron rasar inte förrän en fjärde led har utvecklats, och därmed en mekanism. För att kunna beräkna tvärsnittskrafterna i bågen, var det nödvändigt att känna till trafiklasternas påverkan på bågen när de kördes över bron. För detta ändamål erhölls influenslinjer från en tvådimensionell finita elementmodell skapad i ABAQUS, ett generellt FE-program. En beräkningsrutin för att finna värsta tänkbara lastkombinering skapades i Matlab, ett numeriskt beräkningsprogram. Rutinen utformades för att hitta värsta fallet bland olika lastfall samt för att kombinera standardiserade axeltryck med det aktuella antalet axlar.</p><p>En parameterstudie utfördes också då materialegenskaperna för de olika delarna i bron är mycket osäkra. I parameterstudien ändrades ingångsvärdena ett åt gången för att studera utslaget på lastfaktorn. Lastfaktorn är förhållandet mellan brottgränslasten och den verkliga lasten. De parametrar som studeras är tryckhållfastheten, <em>E</em>-modulen, densiteten och tvärkontraktionen för de olika brodelarna. Parametrarna studeras enskilt utan hänsyn till eventuell korrelation. De brodelar som studeras är fyllningen, bågen, fundamenten och asfalten. Den klart viktigaste komponenten visar sig vara fyllningen. Med ökad styvhet eller ökad tvärkontraktion i fyllningen följer ökad lastfaktor.</p><p>Ekvationerna bakom brottenveloppet kan härledas ur jämviktsekvationer för det oarmerade tvärsnittet. Influenslinjerna normeras med avseende på tvärsnittets kapacitet för att få ut utnyttjandegraden längs hela bågen. Detta görs då det egentligen inte är för stor tvärsnittskraft som orsakar brott utan för stor spänning. Högsta och lägsta utnyttjandegrad för böjande moment och normalkraft lokaliseras när de olika typlasterna körs över bron. Utnyttjandegraderna placeras i brottenveloppet för att sedan räkna fram en lastfaktor.</p><p>Ett flertal liknande broar har lastats till brott i en studie genomförd av British Transport and Road Research Laboratory. En av broarna i studien, Prestwood Bridge, har använts i denna rapport som jämförelse med Glomman. Då bärförmågan hos Prestwood Bridge är känd används den till att bekräfta att metoden med brottenveloppet är tillämpbar.</p><p>För att jämföra resultaten från tvärsnittsanalysen i brottenveloppmetoden med en annan metod, testades även Glomman och Prestwood Bridge i det kommersiella programmet RING 2.0. Metoden som används i RING 2.0 skiljer sig från brottmoden i denna rapport genom att istället beräkna lastfaktorn när fyra olika tvärsnitt har uppnått sina kapaciteter och bron kollapsar.</p><p>Metoden med brottenvelopp tillåter ett A/B-värde (Axel- och Boggitryck) på 102 kN/147 kN när mycket dåliga parametervärden används och 181 kN/226 kN när referensfallet med normala parametervärden används.</p><p>Även om bärförmågan kan anses vara acceptabel är osäkerheterna stora. För att få en nogrannare uppfattning om brons faktiska tillstånd bör fortsatta studier utföras, som t.ex. en icke-linjär modell.</p>
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The effect of a workplace intervention programme on return to work after strokeNtsiea, Mokgobadibe Veronica 06 February 2014 (has links)
Thesis (Ph.D. (Physiotherapy))--University of the Witwatersrand, Faculty of Health Sciences, 2013. / Stroke impacts on a survivor’s ability to participate in community activities such as return to work (RTW) and affects people who are still within the working age. Return to work contributes to life satisfaction and social identity at least partly through independence gained from income-generation. The impact of RTW programmes for stroke survivors is limited and not generalisable to South Africa. This study aimed to bridge this gap in South Africa, and was conducted within the Gauteng province as it comprises the largest share of the South African population.
Objectives and Methodology:
The aim of the study was to determine the current practice in RTW intervention programmes for stroke survivors in the Gauteng Province of South Africa and to establish the effect of a workplace intervention programme on the rate of RTW of previously employed stroke survivors. This study had two stages:
Stage one: A cross sectional survey was performed using a self administered questionnaire to establish current practice in RTW intervention programmes and the therapists’ perceived barriers and enablers of RTW after stroke.
Stage two study included: a) a randomised controlled trial (RCT) to evaluate a six week RTW intervention, with follow-up at three and six months. The workplace intervention programme was tailored according to the functional ability and workplace challenges of each stroke survivor and was as follows: Week one: Assessment for work skill. The assessment included work modules which identified potential problems such as: visual discrimination; eye hand coordination; form and spatial perception; manual dexterity; colour discrimination; cognitive problems, and job specific physical demand factors. Week two: The therapist interviewed the stroke survivor and employer separately to establish perceived barriers and enablers of RTW. This was followed by a meeting between the therapist, stroke survivor and employer/supervisor to discuss and develop a plan to overcome identified barriers and to strengthen identified enablers based on consensus between stroke survivor and employer. Week three: A work visit for the stroke survivor to demonstrate what they did at work and identify what they could still do safely and what they could not do. This included vocational counselling and coaching; emotional support; adaptation of the working environment; advice on coping strategies to compensate for mobility and upper limb functional limitations; and fatigue management. Weeks four, five and six:
continuation of the work visits, while monitoring progress, and making necessary adjustments
as per stroke survivor and employer’s needs. This was done at the workplace while the
participants continued with their usual therapy at the hospital. The control group received usual
care. The primary outcome was RTW rate. The secondary outcomes included activities of daily
living (measured with the Barthel Index); mobility (measured with the Modified Rivermead
Mobility Index); basic cognitive function (measured with the Montreal Cognitive Assessment)
and perceived quality of life (measured with the Stroke Specific Quality of life Scale). Another
aim of stage two study was to: b) establish the stroke survivors’ and employers’ perceived
barriers and enablers of RTW (this was done with the experimental group only); and to: c)
identify predictors of RTW.
Stage one study results: Thirty six (68%) of the 53 questionnaires sent to stroke rehabilitation
facilities were returned. Seventeen (47%) of the 36 clinical settings referred stroke survivors to
facilities offering RTW services; 12 (33%) facilities did not refer stroke survivors for RTW and
did not offer RTW services; and seven (20%) facilities offered RTW services. Of the seven
facilities that rendered RTW services for stroke survivors, five (71%) communicated with the
employer to discuss reasonable accommodation and four (57%) did assessments for potential
to RTW. The most common reason given by the 29 facilities for not offering RTW services was
that they referred stroke survivors to other therapists who offered these services. The second
most common reason was the unemployment status of the stroke survivor at the time of having
stroke. The therapists’ most commonly perceived barriers of RTW were the severity of the
stroke survivors’ physical impairments (n = 3) (36%) and their employment status (n = 11) (31%)
at the time of having stroke. The most commonly perceived enablers were willingness of the
employer to reasonably accommodate the stroke survivor at work (n = 12) (33%), family support
(n = 8) (22%) and increased length of hospital stay to allow for intensive rehabilitation (n = 7)
(19%). Stigma in the workplace was the only variable which had a statistically significant
relationship with the type of clinical facility therapists worked at (p = 0.02).
Stage two study results: The average age for the study group was 45 (SD: 8.7) years and the
average stroke duration was 4.6 (SD: 1.8) weeks. There were 41 (51%) male stroke survivors
and 39 (49%) female stroke survivors. Majority (55%) of the stroke survivors were breadwinners
(63%), had a grade 11 to 12 educational level (64%), an income above R5000 (46%) and had a
helper (74%) whom they did not have to pay (81%). Stroke survivors who returned to work had
better quality of life at six months after stroke than those who did not RTW (p = 0.05).
Results from the qualitative study indicated that the perceived enablers of RTW included: ability of the employer to provide reasonable accommodation and good interpersonal working relationships between stroke survivor, employer and co-workers. The perceived barriers of RTW included: unaffordable reasonable accommodation costs; inaccessible transport; having cognitive (memory and attention) and speech impairments and high unemployment rates.
The overall RTW rate was 20% at three months follow-up and 40% at six months follow-up. Twenty seven percent of the stroke survivors in the intervention group returned to work at three months compared to 12% in the control group (p = 0.13). At six months, the majority of stroke survivors (60%) in the intervention group returned to work compared to 20% in the control group (p <0.001).
The following factors were predictive of RTW: male gender (p = 0.03); fewer speech problems (p = 0.02); increased time off work post stroke (p = 0.001); ability to perform activities of daily living (p = 0.02); good mobility (p = 0.01) and good cognitive ability (p = 0.02). The stroke survivors in the intervention group were 5.2 times more likely to RTW than those in the control group at six months following stroke, and for every unit increase in the activities of the Barthel Index and Montreal Cognitive assessment score, the likelihood of RTW increased by 1.7 and 1.3 respectively.
Conclusion: A RTW intervention consisting of workability assessments and workplace visits was effective in facilitating RTW for stroke survivors in Gauteng province, South Africa. Key predictors of RTW included male gender; increased time off work post stroke; ability to perform activities of daily living; good mobility and good cognitive ability and were identified as facilitating RTW; speech problems were identified as barriers to RTW. Overall, these results suggest the need to direct resources towards increasing work place intervention strategies after stroke.
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Factors that impact on the capacity of district aids task forces to coordinate sustainable decentralized hiv/aids services in Zambia: the case of Lusaka daftChanda, Michael Mulimansenga January 2013 (has links)
Master of Public Health - MPH / Introduction According (UNAIDS/WHO, 2011a) globally, 34.0 million [31.4 million–35.9 million] people were living with HIV at the end of 2011 out of which 80% live in Sub Saharan Africa. In absolute terms, the burden of HIV increased by 354% between 1990 and 2006 (Ortblad et al, 2010). The prevalence of HIV in Zambia stands at 14.3% in the age group 15 to 49 years. Having realized that HIV/AIDS is no longer a health issue alone Zambia embarked on the multisectoral response initiative which allows many stakeholders to play their role. In order to coordinate this multiplicity of stakeholders the government of Zambia created the National HIV/AIDS/STI/TB Council (NAC) with the core mandate to coordinate the national HIV/AIDS response agenda. In turn, the NAC created the Provincial (PATF) and District AIDS Task Forces (DATF) as decentralized structures through which to coordinate the response at provincial and district levels respectively. However, DAFT is not coordinating the response to HIV/AIDS epidemic effectively but the reason for the ineffective coordination has not yet been described. Aim The aim of the study is to explore factors which impact on the capacity of Lusaka DATF to
coordinate an effective and sustainable local HIV/AIDS response. Methods
A descriptive qualitative research was undertaken using purposive sampling methods. Data collection methods included a Document Review, Key Informant Interviews using semi structured interview guides, Focus Group Discussions and Field Notes. Results The study has found that the following factors promote effective coordination of DATF stakeholders and their activities at local level: recognition of the DATF by stakeholders as a formal structure which is enshrined within the institutional framework of the government; joint planning and resource mobilisation for activities by stakeholders particularly around national commemoration days such as World AIDS Day and the National VCT day and holding of stakeholder forum meetings to share experiences and lessons learnt.
The study has also established that the following factors are responsible for preventing the DATF from coordinating effectively include: DATF does not exist as a legal entity enshrined in any Act of Parliament No. 10 of 2002 which created the NAC; there are multiple reporting channels for local stakeholders instead of having only one reporting framework through the DFATF; inadequate stakeholder forums; lack of memoranda of understanding between the DATF and stakeholders; weak technical capacity of the DACA due to factors such as lack of a training programme; inadequate joint planning and resource mobilisation plans and efforts; poor understanding and different interpretations of the of the concept of coordination by different stakeholders; weak feedback mechanisms from the DATF secretariat to stakeholders; and multiplicity of DATF guidelines by different partners which have at times contradicted each other. Poor political, civic and technical leadership engagement has been identified as key inhibiting factors.
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Variantní řešení Obchodního areálu - Dobronická / Alternative solutions of the Business premises - DobronickáWinterová, Karin January 2020 (has links)
The subject of the Master thesis is alternative solutions of the parking lot including review of parking bays and adjacent paved areas for the needs of the shopping area (wholesale of food, eight stores of different charakter, fast food restaurant, fuel station and 3 automatic car wash systems) and design two variants of intersections (direct intersection and roundabout) with new urban road where is the shopping area connected. A traffic survey and capacity assessment of existing and newly proposed variants were carried out for the design of the intersection.
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Capacity assessment of a single span arch bridge with backfill : A case study of the Glomman BridgeBjurström, Henrik, Lasell, Johan January 2009 (has links)
The aim of this Master Thesis is to assess the load carrying capacity of the Glomman Bridge outside of the Swedish city Örebro. The Glomman Bridge is an unreinforced concrete single span arch bridge with backfill. The bridge was constructed in 1923 on assignment from the Swedish National Railways (SJ). The failure criteria used in this thesis is that the bridge collapses when any cross section in the concrete arch reaches its ultimate capacity. In reality, the bridge may manage heavier loads than this. When the capacity is reached in a cross section, a hinge is formed and the arch relocates the forces to other parts of the arch that can carry higher stresses. The real bridge will not collapse until a fourth hinge is formed, and by that a mechanism. To be able to calculate the cross section forces in the arch, it was necessary to know the influences of the loads on the arch when they were run along the bridge. For this purpose, influence lines were obtained from a 2D finite element model created in ABAQUS, a general FE-analyses software. A calculation routine to find the least favourable load combination was then created in Matlab, a numerical calculation software. The routine was made to find the worst case among different load cases and to combine the standardized axle pressures with the present number of axles. A parametric survey was also performed because the material properties for the different parts of the bridge are very uncertain. In the survey, the initial values were changed one at a time to study the outcome on the load factor. The load factor is the ratio between the ultimate limit load and the actual load. The studied parameters are the compressive strength, the Young's modulus, the density and the Poisson's ratio of the different parts of the bridge. The parameters are studied individually irrespective of possible correlation. The studied parts of the bridge are the backfill, the arch, the abutments and the asphalt. The clearly most important component is found to be the backfill. With increased stiffness or increased Poisson's ratio in the backfill follows increased load factor. The equations behind the failure envelope can be derived from equilibrium equations for the unreinforced cross section. The influence lines are normalised with respect to the capacity of the cross section to get the degree of efficiency along the whole length of the arch, instead of the common influence lines that give the cross section forces. This is done because the failure is not caused by large cross section forces but by an exceeded ultimate stress. As the different loads are run along the bridge, the largest positive and negative efficiency for bending moment and normal force are localised. The normalised cross section forces are plotted together with the failure envelope and the load factor is then calculated. Several masonry arch bridges were loaded until collapse in a study performed by the British Transport and Road Research Laboratory. One of the bridges in the study, the Prestwood Bridge, has been used in this thesis as a comparison to the Glomman Bridge. The load carrying capacity of the Prestwood Bridge is known, and is used to verify that the method using the failure envelope is applicable. To compare the results from the cross section analysis from the failure envelope model to another method, the Glomman Bridge and the Prestwood Bridge were also tested in the commercial software RING 2.0. The method used in RING 2.0 differs from the failure mode in this thesis by calculating the load factor when four different cross sections reach their capacity and the bridge collapses. The failure envelope method allows an A/B-value (Axle- and Bogie load) of 102 kN/147 kN when using very poor values of the parameters and 181 kN/226 kN when using a reference case with normal parameters. Although the load capacity is found to be acceptable, the uncertainties are still large. To get a more accurate apprehension of the condition of the actual bridge, further research should be carried out, such as e.g. a non-linear model. / Syftet med föreliggande examensarbete är att uppskatta bärförmågan hos bron Glomman utanför Örebro. Glomman är en oarmerad betongvalvbro i ett spann med ovanliggande jordfyllning. Bron byggdes 1926 på uppdrag av Statens Järnvägar (SJ). Brottkriteriet i detta examensarbete är att bron går till brott när något tvärsnitt i betongbågen uppnår sin kapacitet. I själva verket är det möjligt att bron kan klara tyngre last än detta. När kapaciteten nås i ett tvärsnitt uppstår en led och bågen omlagrar krafterna till andra bågdelar som klarar större spänningar. Den verkliga bron rasar inte förrän en fjärde led har utvecklats, och därmed en mekanism. För att kunna beräkna tvärsnittskrafterna i bågen, var det nödvändigt att känna till trafiklasternas påverkan på bågen när de kördes över bron. För detta ändamål erhölls influenslinjer från en tvådimensionell finita elementmodell skapad i ABAQUS, ett generellt FE-program. En beräkningsrutin för att finna värsta tänkbara lastkombinering skapades i Matlab, ett numeriskt beräkningsprogram. Rutinen utformades för att hitta värsta fallet bland olika lastfall samt för att kombinera standardiserade axeltryck med det aktuella antalet axlar. En parameterstudie utfördes också då materialegenskaperna för de olika delarna i bron är mycket osäkra. I parameterstudien ändrades ingångsvärdena ett åt gången för att studera utslaget på lastfaktorn. Lastfaktorn är förhållandet mellan brottgränslasten och den verkliga lasten. De parametrar som studeras är tryckhållfastheten, E-modulen, densiteten och tvärkontraktionen för de olika brodelarna. Parametrarna studeras enskilt utan hänsyn till eventuell korrelation. De brodelar som studeras är fyllningen, bågen, fundamenten och asfalten. Den klart viktigaste komponenten visar sig vara fyllningen. Med ökad styvhet eller ökad tvärkontraktion i fyllningen följer ökad lastfaktor. Ekvationerna bakom brottenveloppet kan härledas ur jämviktsekvationer för det oarmerade tvärsnittet. Influenslinjerna normeras med avseende på tvärsnittets kapacitet för att få ut utnyttjandegraden längs hela bågen. Detta görs då det egentligen inte är för stor tvärsnittskraft som orsakar brott utan för stor spänning. Högsta och lägsta utnyttjandegrad för böjande moment och normalkraft lokaliseras när de olika typlasterna körs över bron. Utnyttjandegraderna placeras i brottenveloppet för att sedan räkna fram en lastfaktor. Ett flertal liknande broar har lastats till brott i en studie genomförd av British Transport and Road Research Laboratory. En av broarna i studien, Prestwood Bridge, har använts i denna rapport som jämförelse med Glomman. Då bärförmågan hos Prestwood Bridge är känd används den till att bekräfta att metoden med brottenveloppet är tillämpbar. För att jämföra resultaten från tvärsnittsanalysen i brottenveloppmetoden med en annan metod, testades även Glomman och Prestwood Bridge i det kommersiella programmet RING 2.0. Metoden som används i RING 2.0 skiljer sig från brottmoden i denna rapport genom att istället beräkna lastfaktorn när fyra olika tvärsnitt har uppnått sina kapaciteter och bron kollapsar. Metoden med brottenvelopp tillåter ett A/B-värde (Axel- och Boggitryck) på 102 kN/147 kN när mycket dåliga parametervärden används och 181 kN/226 kN när referensfallet med normala parametervärden används. Även om bärförmågan kan anses vara acceptabel är osäkerheterna stora. För att få en nogrannare uppfattning om brons faktiska tillstånd bör fortsatta studier utföras, som t.ex. en icke-linjär modell.
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