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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Soil Steel Composite Bridges. An international survey of full scale tests and comparison with the Pettersson-Sundquist design method

Moreo Mir, Alberto January 2013 (has links)
Nowadays, many different efficient solutions are being studied to solve engineering problems. Inside this group of solutions we can find the Soil Steel Composite Bridges (SSCB) as an alternative to traditional bridges. SSCB are being used more often every day and they are showing themselves as competitive structures in terms of feasibility and constructability. This project was started to achieve two different goals. The first one was to create a general database of SSCB including few selected tests all around the world and the second one was to compare and discuss full scale tests using the Pettersson-Sundquist design method. To create the database and the following comparisons, twenty-five different full scale tests were used. From this tests all the necessary information was extracted and used to create the database. After creating the database, the project continued with the discussion and comparison of the full scale tests. Specifically those discussions and comparisons were related to the resistance of the soil (the soil modulus) used in the construction of the SSCB. All the values of the different soil modulus of each full scale test used in the comparisons were calculated using the Swedish Design Manual (SDM). Two different types of soil modulus were calculated in this project using SDM, ones are the soil modulus back calculated using the values reported from the live load tests performed on the culverts and the others are theoretical soil modulus calculated using the detailed information of the soil. The report continues with the explanation of the different conclusions ended up with during this project. It can be highlighted within this group of conclusions, the one related to the importance of reporting all the necessary information from the full scale tests including the soil parameters, the measures of the culvert, the cross sectional parameters and the vehicle dimensions among others. Another important conclusions are the effect of using the slabs over the top of the culvert and how it would effect to the sectional forces over the culvert and also the limitations using method B of the SDM regarding the type of soil used as backfilling Finally, the project finishes explaining some proposals for future research about other fields of the study of SSCB.
62

Slip Lined Culvert Retrofit and Fish Passage

Webb, Joseph Ray 10 June 2009 (has links) (PDF)
Culverts throughout the country are approaching or are past their original design lives. These ‘baby boomer’ culverts will need to be repaired, rehabilitated, or replaced. Because entire culvert replacement is so expensive and intrusive, alternate measures to extend the culvert project life are growing increasingly popular. One such method is slip lining, where a ‘sleeve’ is installed within an existing culvert barrel and stabilized. Plastic pipe sleeves are very popular for slip lining primarily because the plastic material's lower Manning's roughness values allow for the culvert capacity to be maintained despite a reduction in culvert size. Unfortunately, the reduced friction within the barrel can create a barrier to fish passage due to increased water velocities. The increased velocities also cause greater outlet scour which can result in further obstacles to fish passage. These new fish barriers can greatly affect aquatic ecosystems by limiting the access that fish have to smaller tributaries used for spawning and rearing—access that is critical to the life cycles of many fish. It is suggested that mitigation of the increased velocities should go hand-in-hand with slip lined culvert design projects where fish passage (present or future) is to be considered. Can the demand for hydraulic capacity as well as the demand for fish passage be satisfied? Careful design and installation, coupled with post-project monitoring can result in slip lined culvert retrofits which successfully pass fish. Investigation of federal and state laws and various agency guidelines has informed the creation of a list of culvert conditions which should prompt consideration of slip lined culvert retrofit among other design alternatives. Additionally, a literature review and survey of all U.S. state Departments of Transportation as well as state Fish and Wildlife Departments has shown that there has been very limited experience in providing for fish passage through slip lined culverts. Literature and practice has pointed to the use of baffles and tailwater control weirs for velocity mitigation. Site visits have been made to the few states with this experience to assess developing technologies and record successful and unsuccessful installations. Additional hydraulic analysis using current software suggests general trends in the effects slip lined culvert retrofits on flow type, headwater, velocity as well as the effects of tailwater control weirs. Issues of sustainability, constructability and maintenance, as well as monitoring are addressed.
63

Sediment Transport Conditions Near Culverts

Rowley, Kyle Jay 01 August 2014 (has links) (PDF)
Relatively little work has been done to understand how coarse grained sediments behave near culverts. Particularly for embedded culverts, sediment transport must be understood to achieve sustainable culvert designs for aquatic organism passage and peak discharge requirements. Several culvert sites in the Wasatch Mountains of Utah were studied through the spring flood season of 2014. Data obtained from the culvert sites were used to create numerical models with the Sedimentation and River Hydraulics Two-Dimensional model. The field sites and numerical model were used to study deposition of sediments at the entrance to culverts, sediment replenishment inside culverts, and lateral fining within the culvert barrel. Each element of the study was observed in the field. It was shown that the Sedimentation and River Hydraulics Two-Dimensional model is a useful tool to simulate the observed phenomenon of sediment deposition upstream of culverts, sediment replenishment, and lateral fining. Sedimentation and River Hydraulics Two-Dimensional model should be used in culvert design procedures as a means to understand sediment transport conditions.This work documents the first time that deposition of sediments upstream of a culvert and lateral fining within a culvert barrel have been successfully modeled. The work shows that culvert replenishment occurs naturally in many scenarios and should be simulated as part of the culvert design process. The results from this work will be useful for future design guidelines for culvert installations.
64

Impacts of Road Crossings and Flow on Crayfish Population Structures

Slutzker, Juliet M. 16 April 2015 (has links)
No description available.
65

BEHAVIOUR OF DETERIORATED PIPES REHABILITATED WITH GROUTED SLIPLINERS

Simpson, Bryan 29 November 2013 (has links)
The goals of this research are to develop and validate the use of distributed fibre optic sensors for use in strain monitoring of buried culverts, and to use full-scale experiments to evaluate the performance of both deteriorated steel and reinforced concrete culverts rehabilitated with grouted slipliners subjected to surface loading. Bench scale experiments were conducted to evaluate the use of fibre optic sensors against conventional strain sensors. Then, fibre optic sensors were attached to a full-scale culvert that was tested in a buried state as a proof of concept. Finally, fibre optic sensors were used in two large scale buried pipe tests to explore the performance of rehabilitated flexible and rigid culverts. A deteriorated steel culvert was tested in a buried state under surface loading, then rehabilitated with a grouted high density polyethylene (HDPE) slipliner while still in a buried state and tested under surface loading at 0.9 m and 0.6 m burial depths. The rehabilitated steel pipe was tested under service loading, and up to 1250 kN of applied load. The results suggested that the grouted annulus stiffened the overall structure, and increased the capacity of the system to over 3 times the fully factored design load. A deteriorated reinforced concrete culvert was tested and rehabilitated in a similar fashion. The grout in the annulus penetrated the cracks at the crown, invert and joint of the concrete pipeline. The lined concrete pipe was tested to 1200 kN under single axle loading, and to 800 kN under single wheel loading. The results suggested that while the concrete pipe was stiffened by the grout, it remained the primary contributor to structural capacity, with the liner contributing little to the capacity. Repair reduced the diameter change by an average of 90%, with the capacity reaching approximately 3.3 and 4.2 times the design loads for single axle and single wheel pair loading, respectively. The maximum response was under single axle loading over the barrels of the concrete pipe. In no instance did the structures reach an ultimate limit state, and the tests were stopped after bearing failure of the soil occurred. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-11-28 17:24:50.815
66

Beräkningsverktyg till strategisk planering av framtidens ledningsbundna infrastruktur : Utveckling av modell för LCC- och LCA-analyser av ledningsbunden infrastruktur / Strategic tool for calculation of subsurface infrastructure in the future : Development of a model for combined LCA- and LCC-analyses of subsurface infrastructure

Bergman, Filip, Olsson, Niklas January 2017 (has links)
En ny lag kring hållbarhetsredovisning för företag med samhällsbärande verksamhet innebär att företagen behöver rikta ett större fokus på hållbarhet och därmed minska miljöpåverkan. För att öka hållbarheten och medvetenheten kring vilka kostnader och vilken miljöpåverkan företagets aktiviteter leder till kan ett livscykelperspektiv leda till ökad kunskap och förståelse.Ledningsbunden infrastruktur som el, opto, vatten och avlopp är idag en förutsättning i samhället. Flera av näten som idag används installerades i mitten på 1900-talet vilket innebär att de snart har uppnått sin förväntade livslängd. Med detta följer ökade underhållsarbeten och kostnader för företagen som förvaltar näten. Exempelvis innebär förnyelsen av svenska vatten- och avloppsledningar en årlig investering på 1,9 miljarder kr, något som kommer behöva dubbleras de närmsta 50 åren. 50 % av kostnaderna för att utföra underhållsåtgärder vid konventionell förläggning beror på trafikavstängning och schaktning.Till följd av ovanstående problematik har Tekniska verken arbetat fram en ny lösning för förläggning av ledningsbunden infrastruktur som innebär att ledningsnät för el, opto, vatten, avlopp, sopsug och fjärrvärme förläggs i en kulvert. Kulverten är den första i sitt slag och är gjord av plast med kammare i betong för att sammankoppla rören och dra ut servisledningar. Den första plats som denna infrakulvert installerats på är Vallastaden i Linköping som exploateras för bo- och samhällsexpo 2017.För att utvärdera denna teknik utvecklades i detta examensarbete en modell som kan användas till att beräkna livscykelkostnaderna och miljöpåverkan för infrakulverten och jämföra detta med konventionell förläggning. I examensarbetet begränsades datainsamlingen till att endast studera kostnader och miljöpåverkan har därför inte studerats. Modellen har utvecklats för att ta hänsyn till infrastrukturens stokastiska karaktär och kan beräkna medelkostnader och standardavvikelser samt genomföra detaljerade känslighetsanalyser. Denna typ av modell har ett flertal användningsområden för förvaltande företag då det ger en uppfattning om förväntade kostnader och kan utvärdera risker i samband med investeringar. / A new law concerning sustainability reporting for companies with important functions in society means that companies need a greater focus on sustainability and thus reduce environmental impacts. To enhance sustainability and awareness of the costs and the environmental impacts from its activities, a life-cycle perspective can lead to increased knowledge and understanding.Subsurface infrastructure such as electricity, fiber, water and sewage is now a prerequisite in society. Several of the networks used today was installed in the mid-1900s, which means that they soon have reached their life expectancy. With this follows increased maintenance work and costs for the companies that manage the networks. For example, the renewal of Swedish water and sewage means an annual investment of 1.9 billion SEK, which will have to be doubled over the next 50 years. 50% of the costs to perform maintenance operations with conventional technique is due to traffic shutdown and excavation.As a result of the problems above Tekniska verken has developed an innovation for the installation of piped infrastructure, which involves systems for electrical, optical, water, sewage, waste suction and district heating, placed in a culvert. The culvert is the first of its kind and is made of plastic with concrete chambers to connect the pipes and pull out the service lines. The first place that this infra-culvert is installed in is Vallastaden in Linköping, which is exploited for Bomässan 2017.To evaluate this technology a model was developed in this thesis that can be used to calculate the life cycle costs and environmental impact of infrastructure positioned in the culvert and compare this with conventional technique. The thesis had a limited data collection that only studied the costs and the environmental impact has not been studied. The model has been developed to take into account the infrastructure stochastic nature and can calculate the average cost and standard deviations, and performing detailed sensitivity analyzes. This type of model has a number of uses for companies managing infrastructure as it gives an idea of the expected costs and can evaluate the risks associated with investments.
67

Contribuição ao projeto estrutural de galerias de concreto pré-moldado com seções transversais não usuais / Contribution to the study of precast concrete culverts with unusual cross sections

Domingues, Aline Bensi 20 March 2017 (has links)
As galerias enterradas são amplamente utilizadas em obras de arte corrente (OAC) na infraestrutura de rodovias e ferrovias. Visando disponibilizar mais alternativas na produção de galerias de concreto pré-moldado, a pesquisa apresenta uma análise comparativa de custos para seções transversais não usuais, direcionado a grandes profundidades de instalação. A primeira seção proposta é denominada modificada e é composta por uma base retangular com uma cobertura em arco e a segunda seção proposta é definida por três arcos com uma base plana. Essas seções além de possuir formato de geometria favorável à distribuição dos esforços solicitantes, mantêm o benefício de possibilitar uma compactação adequada do solo na lateral da galeria, como acontece em galerias retangulares convencionais, e isso garante o confinamento do solo e a redistribuição de pressões, graças à mobilização do efeito de arqueamento. Para considerar a interação solo-estrutura foram realizadas análises via elementos finitos com o pacote computacional GeoStudio® próprio para análises geotécnicas. Os resultados comprovaram a interferência do formato das geometrias no comportamento da interação solo-galeria e também evidenciaram que a redução da espessura das paredes da galeria mobiliza em maior intensidade a capacidade resistente do solo e isso reduz os esforços na estrutura. Quanto à análise dos dimensionamentos, com base na comparação dos custos evidenciou-se que, para as galerias modificadas a redução das taxas de armadura está relacionada com flecha do arco da cobertura, sendo que a economia verificada no custo total de materiais das seções estudadas variou de 4 a 29% comparado à galeria retangular. Para a galeria definida por três arcos, confirmou-se que quanto mais alongado for o seu formato, melhor é o comportamento à grandes profundidades de instalação, sendo que a economia verificada no custo total da galeria mais elíptica (DTA I-b) chegou a 50% em relação à galeria retangular e demais geometrias estudadas tiveram economia entre 17 e 42%. / Box culverts are often used in current drainage in the infrastructure of highways and railways. In order to provide more production\'s alternatives of precast concrete culvert, the research presents the comparative cost analysis for unusual cross sections, directed to large depths of installation. The first proposed cross section called modified culvert is composed of a rectangular base with an arc roof. The second is defined by three arcs with a flat base. These cross sections have geometric shapes favorable to the distribution of bending moment and shear forces. It maintains the benefit of adequate compaction of the backfill at the side of the culvert, as well as in conventional box culvert, which ensures ground confinement and pressure redistribution due to the mobilization of the arching effect. In order to consider the soil-structure interaction, finite element analyzes were performed using GeoStudio® software, which is a computational package specific for geotechnical analysis. The results showed that the geometries have influence on the behavior of the soil-culvert interaction, and that the reduction of the thickness of the culvert walls mobilizes the soil resistant capacity, reducing the stresses in the structure. Regarding the structural design, considering the comparison of costs, it was evidenced a reduction of steel reinforcements for the modified culvert, which is related to the arrow of the arc of the cover. The materials saving verified in the total cost of the studied sections ranged from 4% to 29% compared to the box culvert. For the culvert defined by three arches, it was evidenced that the more elongated its geometry, better the behavior for the great depths of installation. The highest materials saving was verified in the total cost of the most elliptical culvert (DTA I-b), which reached a value of 50%. Compared to the box culvert, the others geometries studied had savings between 17-42%.
68

Contribuição ao projeto estrutural de galerias de concreto pré-moldado com seções transversais não usuais / Contribution to the study of precast concrete culverts with unusual cross sections

Aline Bensi Domingues 20 March 2017 (has links)
As galerias enterradas são amplamente utilizadas em obras de arte corrente (OAC) na infraestrutura de rodovias e ferrovias. Visando disponibilizar mais alternativas na produção de galerias de concreto pré-moldado, a pesquisa apresenta uma análise comparativa de custos para seções transversais não usuais, direcionado a grandes profundidades de instalação. A primeira seção proposta é denominada modificada e é composta por uma base retangular com uma cobertura em arco e a segunda seção proposta é definida por três arcos com uma base plana. Essas seções além de possuir formato de geometria favorável à distribuição dos esforços solicitantes, mantêm o benefício de possibilitar uma compactação adequada do solo na lateral da galeria, como acontece em galerias retangulares convencionais, e isso garante o confinamento do solo e a redistribuição de pressões, graças à mobilização do efeito de arqueamento. Para considerar a interação solo-estrutura foram realizadas análises via elementos finitos com o pacote computacional GeoStudio® próprio para análises geotécnicas. Os resultados comprovaram a interferência do formato das geometrias no comportamento da interação solo-galeria e também evidenciaram que a redução da espessura das paredes da galeria mobiliza em maior intensidade a capacidade resistente do solo e isso reduz os esforços na estrutura. Quanto à análise dos dimensionamentos, com base na comparação dos custos evidenciou-se que, para as galerias modificadas a redução das taxas de armadura está relacionada com flecha do arco da cobertura, sendo que a economia verificada no custo total de materiais das seções estudadas variou de 4 a 29% comparado à galeria retangular. Para a galeria definida por três arcos, confirmou-se que quanto mais alongado for o seu formato, melhor é o comportamento à grandes profundidades de instalação, sendo que a economia verificada no custo total da galeria mais elíptica (DTA I-b) chegou a 50% em relação à galeria retangular e demais geometrias estudadas tiveram economia entre 17 e 42%. / Box culverts are often used in current drainage in the infrastructure of highways and railways. In order to provide more production\'s alternatives of precast concrete culvert, the research presents the comparative cost analysis for unusual cross sections, directed to large depths of installation. The first proposed cross section called modified culvert is composed of a rectangular base with an arc roof. The second is defined by three arcs with a flat base. These cross sections have geometric shapes favorable to the distribution of bending moment and shear forces. It maintains the benefit of adequate compaction of the backfill at the side of the culvert, as well as in conventional box culvert, which ensures ground confinement and pressure redistribution due to the mobilization of the arching effect. In order to consider the soil-structure interaction, finite element analyzes were performed using GeoStudio® software, which is a computational package specific for geotechnical analysis. The results showed that the geometries have influence on the behavior of the soil-culvert interaction, and that the reduction of the thickness of the culvert walls mobilizes the soil resistant capacity, reducing the stresses in the structure. Regarding the structural design, considering the comparison of costs, it was evidenced a reduction of steel reinforcements for the modified culvert, which is related to the arrow of the arc of the cover. The materials saving verified in the total cost of the studied sections ranged from 4% to 29% compared to the box culvert. For the culvert defined by three arches, it was evidenced that the more elongated its geometry, better the behavior for the great depths of installation. The highest materials saving was verified in the total cost of the most elliptical culvert (DTA I-b), which reached a value of 50%. Compared to the box culvert, the others geometries studied had savings between 17-42%.
69

An Experimental Study On The Behavior Of Box-shaped Culverts Buried In Sand Under Dynamic Excitations

Ulgen, Deniz 01 September 2011 (has links) (PDF)
Seismic safety of underground structures (culvert, subway, natural gas and water sewage systems) plays a major role in sustainable public safety and urban development. Very few experimental data are currently available and there is not generally accepted procedure to estimate the dynamic pressures acting on underground structures. This study aims to enhance the state of prevalent information necessary in understanding the dynamic behavior of box culverts and the stresses acting under dynamic excitations through experimental analyses. For this purpose, a series of shaking table tests were conducted on box-type culverts buried in dry sand. To simulate the free-field boundary conditions, a laminar box was designed and manufactured for use in a 1-g shake table. Four culvert models having different rigidities were tested under various harmonic motions in order to examine the effect of flexibility ratio on dynamic lateral soil pressures. Based on the tests results, a simplified dynamic pressure distribution acting on sidewalls of the culvert model was suggested. Then, a dynamic lateral coefficient was defined for the proposed peak pressure value in the distribution. The values of this coefficient were obtained as a function of shear strain and relative stiffness between the soil and underground structure. Finally, a simplified frame analysis approach was suggested for the assessment of the forces on the structure, to help to carry out a preliminary design of box-type culverts. In this approach, it was assumed that the culvert was fixed at bottom and subjected to lateral stresses on sidewalls and shear stresses on the upper face. For the confirmation of the method, centrifuge tests were conducted on a box-type culvert model under the Seventh Framework Programme of European Union with Grant Agreement No.227887. Results show that the proposed simplified procedure can be used in reasonable accuracy as a practical approach for the preliminary assessment of box-type culverts buried in dry sand under seismic action.
70

Flexible culverts in sloping terrain : Research advances and application

Wadi, Amer January 2015 (has links)
Although the construction of flexible culverts involves simplicity in comparison to similar concrete structures, the complexity of the beneficial interaction between soil and steel materials requires good understanding for their composite action and performance. Current design methods have certain validity limitations with regard to applicable slopes above the structures. Given the short construction time of flexible culverts, there is an urge to explore the feasibility and the constructability of such as cost-effective structures in sloping terrain, where they may function as an avalanche protection structure for a given road, a culvert under a ski slope, or even as a protection canopy for tunnel entrances. This report compiles the efforts carried out toward gaining knowledge about the different factors that may affect the behaviour of flexible culverts in sloping environment. The report includes an extended summary of the investigation, which is mainly presented in two appended papers. The study involved numerical simulation of three case studies to investigate their performances with regard to soil loading and avalanche loads as well. The height of cover, surface slope intensity, slope stability, soil support conditions, and avalanche proximity, were studied and discussed. The study results allowed realizing the susceptibility of flexible culverts to low heights of soil cover when built in sloping terrain, which is reflected in the deformation response and the incremental change in sectional forces, especially the bending moments. It is also found that increasing the depth of soil cover may feasibly improve the structural performance under asymmetrical soil loading and avalanche loads, where it subsequently help in reducing the bending moments in the wall conduit. The presence of a flexible culvert may affect adversely the soil stability in sloping terrain and thus need to be addressed in design. Furthermore, the flexural response of a flexible culvert is directly influenced by the soil support configuration at the downhill side of the structure. In addition, the report also attempts to highlight some general guidelines about the design aspects of flexible culverts in sloping terrain, and seeks to reflect some of the findings on the design methodology for flexible culverts used in Sweden. / <p>QC 20151130</p>

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