The service life of rigid sewer pipes is often controlled by joint integrity. Leaking joints can cause ingress of water and develop voids where surrounding soil has eroded. The influence of soil voids on the stability of buried rigid pipes is investigated, considering the effects of void size, void location and void shape. A series of simplified void geometries are defined, and their influence on bending moments in the rigid sewer is studied through finite element analysis. Elastic analysis indicates that the bending moments from expanding voids at the springline will increase slowly, accelerating once the void spans a 45 degree arc, approximately doubling at 90 degrees, and tripling if the loosened backfill is modeled for shear failure. This preliminary study suggests that the growth of erosion voids should be stopped before they reach 45 degrees, but validation through physical testing is necessary. Elastic-plastic finite element analysis is used to calculate the deformation of rigid fractured pipe with different thicknesses, considering both bonded and full-slip interface conditions. The analysis confirms that bonded idealized flexible pipe theory is very effective for calculation of increases in horizontal diameter of the fractured pipe. Furthermore, decreases in vertical diameter can be simply related to increase in horizontal diameter using (1-2t/OD) obtained from fractured pipe kinematics. Both elastic and elastic-plastic finite element analyses used to study the deformations of fractured rigid pipe reveal that contact angle appears to be the dominant factor affecting fractured pipe deformations. Deformation of the damaged rigid pipe increases dramatically with void growth and accelerates when erosion void contacts with the outer surface of the pipe over an arc greater than 45 degrees. Computational analyses examine the behavior of centrifuge model tests which examine soil load transfer to flexible sewer liners after fracture and erosion voids form nearby. The magnitude of deformation changes for finite element models is found to be comparable to observations when voids are formed at springline. However the development patterns are dramatically different as voids located under the invert, and it appears that the laboratory test featured physical characteristics that are not modeled in the analysis. / Thesis (Master, Civil Engineering) -- Queen's University, 2007-09-24 20:33:29.689

No description available.

The goal of this thesis is to develop more effective quantitative procedures to evaluate the stability of deteriorated metal culverts and a better understanding of the deteriorated culverts' behaviour through non-destructive testing, full scale experiments and numerical analyses. First, three design cases were examined using numerical analysis to study the effects of corrosion, burial depth and staged construction on the capacity of deteriorated steel culverts. Then, a method to measure the remaining wall thickness of two 1.8 m diameter corroded metal culverts using ultrasonic device was developed. Both culverts were then buried in the test pit at Queen's University and tested under nominal and working vehicle loads at 0.9m cover and 0.6m cover. The more heavily corroded structure (CSP1) was tested up to its ultimate limit state, inducing local bending across the crown, as well as local buckling of the remnants of the corrugated steel wall between perforations at the haunches. The results suggest that the single axle pads interact to influence the culvert's behaviour despite the shallow cover used in these experiments. CSP1 was able to carry the working load and did not fail until reaching 340 kN, which was equal to 90% of the fully factored load. The experiment suggests that less deteriorated metal culverts (as compared to CSP1) may have the required capacity. Two finite element packages, CANDE and ABAQUS, were used to perform the numerical investigation and the AASHTO and CHBDC approaches were then used to calculate the thrust force in the culverts. Although the numerical analysis produced conservative values for the thrust forces, it failed to capture the non-linear behaviour of both specimens in the experiments. Both the AASHTO and the CHBDC approaches produced unconservative thrust forces compared to experimental results while numerical analysis using Moore's spreading factor produced the most conservative results in terms of thrust. The analysis suggests that CANDE could be used to predict thrust forces in less deteriorated metal culverts. A procedure to assess the stability of deteriorated corrugated metal culverts based on quantitative data was developed using the numerical analysis and experimental results. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-01-30 12:56:17.945

The U.S. Congressional Research Service issued a report for Congress in May 2016, entitled” Earthquake Risk and U.S. Highway Infrastructure: Frequently Asked Questions” which highlighted the absence of a national database on the status of seismic vulnerability of bridges or other infrastructure, and thus no estimate of costs to retrofit vulnerable bridges. Low to moderate seismicity regions exist in each of the continental United States, with over 30 states having mostly or entirely low-to-moderate seismicity. Resources at state transportation agencies and municipalities are focused on higher seismicity regions, creating a gap in quantifying the system-wide seismic vulnerability despite an overall aging bridge inventory, much of which was built before current seismic design standards. This research addressed this data gap and reduces barriers to quantifying seismic vulnerability of existing bridges in low-to-moderate seismicity regions. The work included nonlinear dynamic numerical modeling of typical multiple span bridge configurations in both pristine and deteriorated conditions, by subjecting them to seventy ground motions across four low-to-moderate seismic hazard levels, to evaluate their seismic performance. These typical bridge configurations represent over 160,000 bridges, which comprise 55 % of the multiple span bridges nationwide. The research results indicate that there is an overall low probability of significant seismic damage to these typical bridges in such regions. The results also show that current seismic hazard thresholds used for the design of new bridges, and for retrofit of existing bridges, which provide the basis for exempting some bridges from specific seismic analysis and design, can underestimate the expected seismic forces. Those results can be used to refine those exemption thresholds to provide appropriate protection against potential seismic damage in those cases. The study results also formed the basis for a system-wide rapid seismic vulnerability screening algorithm developed for the Vermont bridge inventory, which is applicable to other states with low to moderate seismicity regions.

Convective heat transfer to CO2 flowing upward in electrically heated vertical tubes at supercritical pressures was studied for wall heat fluxes q within ranges that included values corresponding to the onset of heat transfer deterioration (HTD). The inlet pressure was P = 8.35 MPa, the mass flux was in the range 200 kg/m2s ≤ G ≤ 1500 kg/m2s, and the inlet temperature was in the range 0 ◦C ≤ Tin ≤ 35 ◦C. Wall temperature measurements were collected in three tubular test sections, having inner diameters of D = 4.6, 8, and 22 mm. The abilities of three different HTD identification methods to separate the entire data set into deteriorated and normal heat transfer modes were tested. Two types of buoyancy parameters were tested as HTD detection methods, and correction factors for changes in mass flux were devised. The minimum heat flux at HTD onset was found to follow a power law of mass flux with the same exponent for all three sections and the same proportionality coefficient for the two smaller sections but a smaller one for the larger test section. For heat flux values that were larger than this minimum, HTD was found to occur only within a limited range of Tin, whose width increased with increasing heat flux. The heat transfer coefficient for normal heat transfer was expressed as an exponential function of the diameter.

The Hampton Roads Bridge-Tunnel is one of the oldest prestressed concrete structures in the United States. The 3.5 mile long twin structure includes the world's first underwater tunnel between two man-made islands. Throughout its 60 years in service, the harsh environment along the Virginia coast has taken its toll on the main load carrying girders. Concrete spalling has exposed prestressing strands within the girders allowing corrosion to spread. Some of the more damaged girders have prestressing strands that have completely severed due to the extensive corrosion. The deterioration has caused select girders to fail the necessary load ratings. The structure acts as an evacuation route for the coast and is a main link for the local Norfolk Naval Base and surrounding industry. Because of these constraints, load posting is not a viable option. Live load testing of five spans was performed to investigate the behavior of the damaged spans. Innovative techniques were used during the load test including a wireless system to measure strains. Two different deflection systems were implemented on the spans, which were located about one mile offshore. The deflection data was later compared head to head. From the load test results, live load distribution factors were developed for both damaged and undamaged girders. The data was also used by the local Department of Transportation to validate computer models in an effort to help pass the load rating. Overall, this research was at the forefront of the residual strength of prestressed concrete girders and the testing of in-service bridges. / Master of Science / According to Federal law, each bridge across the United States must be inspected by a licensed engineer on a biennial cycle – meaning every two years. Roughly every ten years, or when major work is performed such as a bridge widening, a load rating must be performed. During a load rating, licensed structural engineers analyze every structural component of a bridge under various loads. These loads include general traffic loads, heavy design loads, as well as special permit truck loads. For each of these loadings, it is proven whether each structural component has enough strength to withstand the load entering the member. Inspection reports are incorporated into the load rating analysis to account for any deterioration in the members which will lower its strength. Recently, a load rating was performed on the Hampton Roads Bridge-Tunnel. The Bridge-Tunnel is a 3.5 mile long twin structure located in Southeastern Virginia. Throughout its 60 years in service, the harsh coastal environment has caused extensive deterioration to some of its main load carrying girders. The deterioration has caused the Bridge-Tunnel to fail its load ratings meaning load posting may have to be imposed. This means signs, and possibly security guards, would have to be implemented before the approach ramps preventing trucks over a certain weight limit from entering. The structure acts as an evacuation route for the coast and is a main link for the local Norfolk Naval Base and surrounding industry. Because of these constraints, load posting is not a viable option. The Bridge-Tunnel is one of the oldest structures of its type so the effects of the deterioration are not well understood causing conservative assumptions to be used within the load rating. This research describes load testing that was performed on the structure to understand the performance and deterioration effects of the bridge. The results and recommendations from this research were used by the load rating engineers to justify assumptions made and help pass the load rating.

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

<p>Denna rapport är en jämförande studie av utvalda konsolidanter som används till att stabilisera nedbrutet insektsangripet trä. Av de trägnagande skadeinsekter vi har i Sverige är det främst<em> </em>den<em> </em>strimmiga trägnagaren som är intressant i möbelsammanhang. I rapporten beskrivs den strimmiga trägnagaren, en liten skadeinsekt<strong> </strong>som kan åstadkomma stor skada om den får verka ostörd. Insekten finns utspridd i hela Europa och är ett stort problem då den angriper alla typer av träslag. Nedbrutet insektsangripet trä<strong> </strong>förlorar sin styrka och kan behöva konsolideras genom att injicera konsolidanter in i träet. Studien är tänkt att jämföra styrkan på de vanligast förkommande och använda konsolidanterna. Urval av dessa har dels gjorts genom att intervjua konservatorer i Sverige, Norge och Danmark, dels utifrån tillgänglig litteratur och forskning. I studien injiceras de utvalda konsolidanterna in i provbitar av artificiellt konstruerat insektsangripet trä som sedan utsätts för hållfasthetsprover. Provbitarna är utformade i kuber av björk, 45x45x45 mm och är borrade med 2 mm stora hål för att efterlikna angripet trä. Två olika typer av hållfasthetsprov har använts för att mäta styrkan hos de olika konsolidanterna, tryckhållfasthet tvärsfiber och skjuvhållfasthet. Resultaten av hållfasthetsproverna visar inga tydliga tecken på att de injicerade konsolidanterna gett någon direkt styrka till provbitarna. I tryckhållfasthets tvärsfiber finns en dock en tendens tillförhöjda värden. För att kunna dra någon slutsats bör ytterligare studier genomföras.</p> / <p>This report is a comparative study of a chosen set of consolidating agents used to stabilize wood suffering from the infestation of wood boring insects. When considering furniture, the most common wood boring insect in Sweden is the Furniture Beetle. This report discusses the Furniture Beetle, a small insect which if left alone, achieves a great amount of damage. This particular beetle can be found in all of Europe and is a sizable problem, since it can attack all species of wood. Infested wood is destabilized by the beetles boring a web of internal tunnels throughout, which results in a loss of strength. This wood is then commonly injected with a consolidation agent to compensate for its internal weakness. The study is made to compare the strength of the most commonly used consolidating agents. These lection of agents was determined by interviewing conservators in Sweden, Norway and Denmark, as well as from accessible literature and research. In the study the selected consolidating agents are injected into trial pieces of artificially compromised wood which are in turn exposed to strength testing in a laboratory setting. The trial pieces are squares of birch wood measuring 45x45x45mm which have several 2mm holes drilled into them lengthwise, to simulate the beetle's pathways. Two types of strength testing were carried out to test the consolidation agents and their effect. One testmeasures the strength by compression across the grain, while the other puts pressure on either side, forcing the piece to fail along the grain. The results of the testing do not distinctively show that the consolidating agents impose any significant strength to the trial pieces. There is however a tendency of increased strength shown in the cross grain compression tests. To draw any firm conclusions, additional research is required.</p>

Denna rapport är en jämförande studie av utvalda konsolidanter som används till att stabilisera nedbrutet insektsangripet trä. Av de trägnagande skadeinsekter vi har i Sverige är det främst den strimmiga trägnagaren som är intressant i möbelsammanhang. I rapporten beskrivs den strimmiga trägnagaren, en liten skadeinsekt som kan åstadkomma stor skada om den får verka ostörd. Insekten finns utspridd i hela Europa och är ett stort problem då den angriper alla typer av träslag. Nedbrutet insektsangripet trä förlorar sin styrka och kan behöva konsolideras genom att injicera konsolidanter in i träet. Studien är tänkt att jämföra styrkan på de vanligast förkommande och använda konsolidanterna. Urval av dessa har dels gjorts genom att intervjua konservatorer i Sverige, Norge och Danmark, dels utifrån tillgänglig litteratur och forskning. I studien injiceras de utvalda konsolidanterna in i provbitar av artificiellt konstruerat insektsangripet trä som sedan utsätts för hållfasthetsprover. Provbitarna är utformade i kuber av björk, 45x45x45 mm och är borrade med 2 mm stora hål för att efterlikna angripet trä. Två olika typer av hållfasthetsprov har använts för att mäta styrkan hos de olika konsolidanterna, tryckhållfasthet tvärsfiber och skjuvhållfasthet. Resultaten av hållfasthetsproverna visar inga tydliga tecken på att de injicerade konsolidanterna gett någon direkt styrka till provbitarna. I tryckhållfasthets tvärsfiber finns en dock en tendens tillförhöjda värden. För att kunna dra någon slutsats bör ytterligare studier genomföras. / This report is a comparative study of a chosen set of consolidating agents used to stabilize wood suffering from the infestation of wood boring insects. When considering furniture, the most common wood boring insect in Sweden is the Furniture Beetle. This report discusses the Furniture Beetle, a small insect which if left alone, achieves a great amount of damage. This particular beetle can be found in all of Europe and is a sizable problem, since it can attack all species of wood. Infested wood is destabilized by the beetles boring a web of internal tunnels throughout, which results in a loss of strength. This wood is then commonly injected with a consolidation agent to compensate for its internal weakness. The study is made to compare the strength of the most commonly used consolidating agents. These lection of agents was determined by interviewing conservators in Sweden, Norway and Denmark, as well as from accessible literature and research. In the study the selected consolidating agents are injected into trial pieces of artificially compromised wood which are in turn exposed to strength testing in a laboratory setting. The trial pieces are squares of birch wood measuring 45x45x45mm which have several 2mm holes drilled into them lengthwise, to simulate the beetle's pathways. Two types of strength testing were carried out to test the consolidation agents and their effect. One testmeasures the strength by compression across the grain, while the other puts pressure on either side, forcing the piece to fail along the grain. The results of the testing do not distinctively show that the consolidating agents impose any significant strength to the trial pieces. There is however a tendency of increased strength shown in the cross grain compression tests. To draw any firm conclusions, additional research is required.

This thesis describes the development and validation of a look-up table capable of predicting heat transfer to water flowing vertically upward in a circular tube in the trans-critical pressure range from 19 to 30 MPa. The table was based on an extensive and screened experimental database and its trends were smoothened to remove unrealistic scatter and physically implausible discontinuities. When compared to other prediction methods, the present look-up table approximated the experimental data closer in values and trends. Moreover, unlike existing prediction methods, the table applies not only to normal heat transfer conditions but also to conditions with heat transfer deterioration and enhancement. A separate multi-fluid look-up table for trans-critical heat transfer was also developed, which besides the existing water database incorporated new measurements in carbon dioxide; the latter were collected at the University of Ottawa supercritical flow loop under conditions of interest for the current Super-Critical Water-Cooled Reactor designs, for which few water data were available in the literature. Existing fluid-to-fluid scaling laws were tested and two additional sets of scaling laws were proposed, which are applicable not only to the supercritical pressure region, but also to the high pressure subcritical region. The multi-fluid table is applicable to water at conditions of normal and abnormal heat transfer, but its applicability to model fluids is restricted to the normal heat transfer mode.