In the last twenty years, the design requirements of bridge barriers have changed with the aim of improving the safety of commuters on the bridge. A majority of precast concrete bridge barriers (PCBB) on highway bridges in British Columbia were designed and installed in accordance with the 1988 Canadian Highway Bridge Design Code (CHBDC). To ensure that these barriers comply with the current code requirements, research and testing were deemed obligatory. In particular, the anchorage capacity of the parapet under the CHBDC design load warrants verification. A finite element model of the barrier was developed in ANSYS to study its structural response. Static testing of a set of barriers was carried out at the University of British Columbia to better understand the behaviour of the barrier. The experimental results were used to calibrate and verify the finite element model. Through the finite element model and experimental results, a simpler model has been developed in a formatted spreadsheet environment to allow better estimates of the anchorage capacity of different barrier designs. The model was scaled to a wider use for practicing engineers so to ease and improve the design of anchorages of precast concrete bridge barrier under Performance Level 2 loading in accordance with the Canadian Highway Bridge Design Code.

In the last twenty years, the design requirements of bridge barriers have changed with the aim of improving the safety of commuters on the bridge. A majority of precast concrete bridge barriers (PCBB) on highway bridges in British Columbia were designed and installed in accordance with the 1988 Canadian Highway Bridge Design Code (CHBDC). To ensure that these barriers comply with the current code requirements, research and testing were deemed obligatory. In particular, the anchorage capacity of the parapet under the CHBDC design load warrants verification. A finite element model of the barrier was developed in ANSYS to study its structural response. Static testing of a set of barriers was carried out at the University of British Columbia to better understand the behaviour of the barrier. The experimental results were used to calibrate and verify the finite element model. Through the finite element model and experimental results, a simpler model has been developed in a formatted spreadsheet environment to allow better estimates of the anchorage capacity of different barrier designs. The model was scaled to a wider use for practicing engineers so to ease and improve the design of anchorages of precast concrete bridge barrier under Performance Level 2 loading in accordance with the Canadian Highway Bridge Design Code.

In the last twenty years, the design requirements of bridge barriers have changed with the aim of improving the safety of commuters on the bridge. A majority of precast concrete bridge barriers (PCBB) on highway bridges in British Columbia were designed and installed in accordance with the 1988 Canadian Highway Bridge Design Code (CHBDC). To ensure that these barriers comply with the current code requirements, research and testing were deemed obligatory. In particular, the anchorage capacity of the parapet under the CHBDC design load warrants verification. A finite element model of the barrier was developed in ANSYS to study its structural response. Static testing of a set of barriers was carried out at the University of British Columbia to better understand the behaviour of the barrier. The experimental results were used to calibrate and verify the finite element model. Through the finite element model and experimental results, a simpler model has been developed in a formatted spreadsheet environment to allow better estimates of the anchorage capacity of different barrier designs. The model was scaled to a wider use for practicing engineers so to ease and improve the design of anchorages of precast concrete bridge barrier under Performance Level 2 loading in accordance with the Canadian Highway Bridge Design Code. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Ground anchorages are the main support for the structures as tunnels, mines and retaining walls. Both BS8081: 1989 and current practice suggest that there is a need for anchorages to be installed cost-effectively and monitored efficiently in terms of their long-term condition. An EPSRC research project was carried out to investigate the application of the GRANIT system developed at the University of Aberdeen, a proven viable long-term condition monitoring system for rock anchorage, to soil anchorages incorporating soil behaviour.

Since the introduction of temporary skeletal anchorage in orthodontics during the eighties, osteosynthesis miniplates, modified with orthodontic attachments, have been increasingly used. However, no quantitative data about bone reactions around loaded miniplates, and only few prospective clinical studies with small numbers of patients, were found in the literature. Therefore, this project was set up to scientifically emphasize the use of miniplates for orthodontic anchorage with combined experimental and clinical approaches. The specific objectives of the experimental chapters of this thesis were to evaluate if orthodontic loading has an impact on bone reactions around screws supporting miniplates, and to describe the histological components of the bone-screw interface. The clinical chapters aimed to determine patients’, orthodontists’ and surgeons’ perceptions about miniplates, to assess their success rate and to describe the surgical techniques of placement and removal. The experimental study involved eighty miniplates, placed in the jaws of 10 dogs : 2 miniplates per jaw quadrant. After 2 weeks, coil springs applying a 125 g force were placed between the miniplates of an upper quadrant and the controlateral lower quadrant of each dog. The other miniplates were not loaded and were considered controls. Five dogs were sacrificed 7 weeks after implantation and 5 dogs after 29 weeks. Fluorochromes were injected at implantation and at sacrifice. Jaw quadrants were scanned with peripheral Quantitative Computed Tomography. Undecalcified sections were carried out and submitted to microradiographic analysis to assess bone-implant contact and bone volume/total volume. The sections were finally observed under UV light, stained and examined under ordinary light. The success rate in this animal study was 53 % and the proportion of stable miniplates was significantly higher in the maxilla than in the mandible. No significant difference in success rate was found between loaded and nonloaded miniplates. Mobility occurred on average 5 weeks after placement. Bone mineral density was higher around mandibular than around maxillary miniplates, but was not significantly different around loaded and nonloaded miniplates. Bone implant contact and bone volume/total volume did not differ significantly neither between the loaded and the nonloaded screws, nor according to the direction of load, whereas they increased with time. Fifty-six percent of the screws were osseointegrated. Healing reactions showed mainly limited remodelling of lamellar bone. The remaining screws were fibro-integrated. Stability and osseointegration of titanium orthodontic miniplates were thus influenced by the recipient site anatomy, but not by loading. The clinical study focused on ninety-seven consecutive patients treated with miniplates, who completed questionnaires. A total of 200 miniplates were placed by nine oral surgeons, who filled out questionnaires after placement and removal surgeries. The 30 orthodontists treating these patients also completed questionnaires concerning miniplate success, handling complexity, and effectiveness. The success rate obtained in this clinical survey was 92.5 %. Placement surgery, generally performed under local anesthesia, lasted on average 15-30 minutes per plate, and was considered by the surgeons to be very to moderately easy. Patients tolerated the miniplates well : 72 % of patients said they did not mind having the implant and 82 % reported that the surgical experience was better than expected, with little or no pain. The chief complaints were post-surgical swelling, lasting 5 days on average, and cheek irritation. The orthodontists rated these devices as easy to use and simplifying treatment. The removal surgery was shorter and considered easier than the placement surgery. Miniplates were thus well accepted by patients and providers, and were considered a useful tool especially for difficult treatments.

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This thesis describes the development of the lumped parameter model and the results obtained from it. In order to fully utilise the response signatures obtained from GRANIT, it is essential to understand the effect of the various components of the 'complete ground anchorage system' such as protruding free and fixed length of the anchorage, anchorage head assembly, affected and non-affected rock mass. In order to monitor each subsystem and its dynamic response to potential changes/failures, the anchorage system, in its simplest form, is represented by the model which comprises seven masses and a number of spring/damper systems replicating the components described earlier. Ordinary differential equations for mass/spring/dash-pot elements were then configured and the model was implemented in software form and then solved for both time and frequency domain. The acceleration response was examined at a number of points in the anchorage system i.e. at the protruding length as well as at the anchorage head, along the free length, along the fixed length and even within the rock mass itself. Several laboratory and field anchorage applications were simulated using the lumped parameter model and the results obtained from the model. A parametric study was then undertaken with regard to addressing mechanisms which are generally present in anchorage applications such as changes of material properties of the resin and concrete, the introduction of defects, such as gaps along the fixed anchorage length or debonding at the proximal fixed anchorage length, and the influence of changes in post tension load on the dynamic response of the anchorages. Furthermore, an investigation of the impulse load was conducted with the aim of further development of the current impact device in order to be able to assess anchorages regarding the mechanisms mentioned earlier.

Project (M. Eng.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 44-45). Also available via the Internet.

Thesis (Ph.D.)--Aberdeen University, 2008. / Title from web page (viewed on Mar. 9, 2009). Includes bibliographical references.

The Near Surface Mounted (NSM) strengthening is an emerging retrofitting technique, which involves bonding Fibre Reinforced Polymer (FRP) reinforcement into grooves cut along the surface of a concrete member to be strengthened. This technique offers many advantages over external bonding of FRP reinforcement, for example, an increased bond capacity, protection from external damage and the possibility of anchoring into adjacent concrete members. To date, significant research has been conducted into the NSM FRP strengthening technique. However, there are still some areas which need further research in order to fully characterise bond and anchorage of NSM FRP bars. Lack of experimental data, design tools and analytical models addressing these areas create obstacles for the efficient use of these advanced polymer materials. The particular objectives of the research are; to investigate bond behaviour between NSM FRP bars and concrete, to understand the critical failure modes involved and their mechanics, and to develop a rational analytical model to predict bond strength and anchorage length requirements for NSM FRP bars. Several significant variables affecting bond, such as bond length, size, shape and type of bar, resin type, groove dimensions and concrete strength, have been considered. In particular, attention has been focussed on the effect of bar shape on bond behaviour. A comprehensive set of laboratory testing and their results, including the effect of the investigated parameters are presented. Various modes of anchorage failure of NSM FRP bars are identified and the underlying mechanics are investigated. Analytical models are developed to predict bond capacity and anchorage length requirements of NSM FRP bars, and are verified with experimental results.