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.

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.

No description available.

Vita. / Digitized by Kansas Correctional Industries

No description available.

Helical anchors are a type of deep foundation element that can be installed quickly in almost any location and can accept the immediate application of operational loads. The use of helical anchors has expanded in recent decades from its established application in the power transmission industry to more traditional civil engineering applications such as residential construction, communication tower installations, and static and seismic structural retrofitting and reconstruction. Despite the wide range of helical anchor applications, few advances have been made in improving the understanding of their behavior. For example, existing helical anchor design methods, for cases where the anchors are loaded in uplift in cohesive soils, are based on the assumption that the soil above the helical plate is mobilized in a manner analogous to that beneath a deep foundation in bearing. An appropriate design method would acknowledge the effect of load directionality on the assumed failure mechanism. This thesis evaluates the existing cylindrical shear and individual plate bearing design methods for helical anchor capacity in uplift. Additionally, new capacity models are proposed to improve prediction accuracy and reduce prediction variability. A load test database of helical anchors loaded in tension is established from tests reported in the literature. The existing and proposed capacity models are compared to the capacities observed during loading tests using the statistical bias and its distribution. Load and Resistance Factor Design (LRFD) resistance factors are derived from closed-form solutions using First Order Second Moment (FOSM) reliability procedures. Finally, load-displacement models are developed through the evaluation of observed individual anchor plate breakout behavior and back-calculation of side shear capacity from load tests on multi-plate anchors. The new displacement models are compared to the load-displacement tests in the database. In general the comparisons indicate that the displacement-based models developed in this thesis provide a reasonable estimate of load-displacement behavior of helical anchors for service-level displacements. These findings provide engineers with new tools for design of helical anchor foundations. / Graduation date: 2012

Existing reinforced concrete (RC) structural members such as beams, columns and joints can be strengthened and repaired with externally bonded high-strength and light-weight fibre-reinforced polymer (FRP) composites. The effectiveness of such strengthening can, however, be limited by premature debonding of the FRP at strains well below the strain capacity of the FRP. Such failures are also generally sudden and give rise to brittle member behavour. It is therefore important to prevent or even delay debonding failure in order for the FRP strengthening to be more effectively and efficiently used. Anchorage of the FRP strengthening is a logical solution and to date several different types of anchorage systems have been developed and tested. Anchors made from FRP, which are herein referred to as FRP anchors, are singled out for deeper inspection in this doctoral program of research. FRP anchors are an attractive form of anchorage as they are non-corrosive, relatively easily made by hand, and can be used in a variety of shaped RC elements ranging from beams to walls. There have been limited systematic studies though conducted on anchorage devices including FRP anchors. This knowledge gap forms the scope of the program of doctoral research reported herein. This dissertation is concerned with investigating the ability of FRP anchors to anchor externally bonded FRP in flexural strengthening applications. This is done by investigating the influence of FRP anchors on FRP-to-concrete bonded interfaces. Following a review of relevant literature, tests on FRP-to-concrete joints anchored with FRP anchors are reported as well as tests on FRP-strengthened RC slabs anchored with FRP anchors. The joint tests are used to investigate and understand the influence of key geometric and material properties such as, but not limited to, anchor type and position as well as plate length. The optimal arrangement of FRP anchors enabled significant increases in FRP plate strain utilisation to be achieved in the joints. Two modelling approaches based on regression analysis as well as partial interaction modelling are developed for the modelling of the joint tests. In the latter method of analysis, the complete debonding process is able to be simulated. The test and modelling results of the joint specimens are then used to design anchorage schemes for application to RC slabs strengthened in flexure with externally bonded FRP plates. The slab test results show the importance of strategic FRP anchor installation for enhancing the strength, ductility and deformability of FRP-strengthened RC slabs. Future research needs are finally presented in light of the outcomes of the experimental and analytical components of the research reported herein. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

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