Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 69-79). Also available on the World Wide Web.

M.Ing.(Electrical and Electronic Engineering) / The study investigated whether non-destructive impact testing, aided by supervised machine learning methods, could be used to identify improper roof bolt installations, related to insufficient grout coverage. The testing method involved the installation of four roof bolts, with varying installation properties, into a 1511 × 940 × 1350mm rock test block. Three fully grouted bolts served as examples of proper installations, with the fourth bolt grouted only up to half the length of the borehole serving as an improper roof bolt installation. The testing procedure involved placing sensors directly onto the bolts and mechanically impacting a chosen bolt while measuring the response on all the bolts. The focus was on gaining understanding of the working principle of the testing technique and how the measured response was influenced by the presence of signal-modifying factors of the physical test block geometry, such as changes in material properties, boundary changes, cracks or empty boreholes. It was shown that the roof bolt integrity testing method aided by supervised machine learning methods could identify and classify both properly and improperly grouted roof bolts on the small sample of test bolts, in a series of tests conducted at the CSIR Centre for Mining Innovation premises. The method was also shown to be robust enough to do so even in the presence of the signal-modifying factors of the physical test block geometry.

Several design equations for predicting the capacity of a single-headed anchor bolt embedded in plain concrete have been recommended in the United States. The capacities computed by these different recommendations, in some cases, differ significantly. The existing differences in current design criteria for anchor bolts subjected to tensile or shear loading is discussed with emphasis on the ACI, the PCI and the proposed Load and Resistance Factor Design (LRFD) equations. Available data from test results on the anchor bolts and welded studs were analyzed. Then, based on the analysis of these data and statistical information on basic design variables, a reliability analysis was performed. Using the advanced first-order second-moment reliability analysis method, risk levels implied in these design equations were computed for a dead and maximum live load combination. It was found that there are inconsistencies in the levels of safety implied by both the ACI and the PCI design equations, and that the level of safety depends on the loading and the failure mode under consideration. By comparing reliability indices for these design equations, it is thus possible to make an objective evaluation of current design criteria. / Master of Science

No description available.

The gradual depletion of shallow water hydrocarbon deposits has forced the offshore oil and gas industry to develop reserves in deeper waters. Dynamically installed anchors have been proposed as a cost-effective anchoring solution for floating offshore structures in deep water environments. The rocket or torpedo shaped anchor is released from a designated drop height above the seafloor and allowed to penetrate the seabed via the kinetic energy gained during free-fall and the anchor’s self weight. Dynamic anchors can be deployed in any water depth and the relatively simple fabrication and installation procedures provide a significant cost saving over conventional deepwater anchoring systems. Despite use in a number of offshore applications, information regarding the geotechnical performance of dynamically installed anchors is scarce. Consequently, this research has focused on establishing an extensive test database through the modelling of the dynamic anchor installation process in the geotechnical centrifuge. The tests were aimed at assessing the embedment depth and subsequent dynamic anchor holding capacity under various loading conditions. Analytical design tools, verified against the experimental database, were developed for the prediction of the embedment depth and holding capacity.

Caisson or pier foundations are encountered as part of the foundation system of tall structures such as bridges, transmission towers, heliostats, etc, and correspond to rigid blocks of length-to-diameter (D/B) ratio on the order of D/B = 2-6. As a result of their geometry and stiffness characteristics, the mechanisms of load transfer from the superstructure to the surrounding soil and their kinematic response to seismic wave propagation are governed by a complex stress distribution at the pier-soil interface, which cannot be adequately represented by means of simplified Winkler models for shallow foundations or flexible piles. Continuum model solutions, such as 3D finite elements (FE) cannot be employed frequently in practice for the design of non-critical facilities due to the cost and effort associated with these analyses. The objective of this work is to develop a Winkler-type model for the analysis of transversely-loaded caissons, which approximately accounts for all the main soil resistance mechanisms mobilized, while retaining the advantages of simplified methodologies for design at intermediate levels of target accuracy. Investigation of the governing load-transfer mechanisms and development of complex spring functions is formulated on the basis of 3D FE simulations. Initially, the soil-structure stiffness matrix is computed by subjecting the pier to transverse static and dynamic loading at the top, and numerically estimating the response. Complex frequency-dependent functions are next developed for the spring constants by equating the stiffness matrix terms to the analytical expressions developed for the four-spring model. Sensitivity analyses are conducted for optimization of the truncated numerical domain size, finite element size and far-field dynamic boundary conditions to avoid spurious wave reflections. Simulations are next conducted to evaluate the transient response of the foundation subjected to vertically propagating shear waves, and results are compared to the response predicted by means of the 4-spring model. Finally, the applicability of the method is assessed for soil profiles with depth-varying properties. While the methodology developed is applicable for linear elastic media with no material damping, the expressions of complex spring functions may be extended to include hysteretic damping, nonlinear soil behavior and soil-foundation interface separation, as shown in the conclusions.

The present thesis is an attempt to investigate the interference effects on the magnitudes of the ultimate failure loads for a group of closely spaced strip footings and strip plate anchors. On account of an increase in the number of different civil engineering structures, footings and anchors are often need to be placed very close to each other. In such a situation, the ultimate bearing capacity/pullout capacity of an interfering footing/anchor becomes significantly different from that of a single isolated footing/anchor. The effect of interference on the magnitude of failure load is usually expressed in terms of an efficiency factor (%y); where £,y is defined as the ratio of the magnitude of the failure load for a strip footing/anchor of a given width in the presence of other footings/anchors to that of the magnitude of the failure load for an isolated single strip footing/anchor having exactly the same width. No rigorous analysis seems to have been carried out so far in literature to investigate the interference effect for a group of footings and anchors. In the present study, it is intended to use rigorous numerical upper bound limit analysis in combination with finite elements and linear programming in order to determine the collapse loads for the problems of both isolated and a group of footings and anchors. Three noded triangular elements are used throughout the thesis for carrying out the analysis for different problems. The velocity discontinuities are employed along the interfaces of all the elements. The plastic strains within the elements are incorporated by using an associated flow rule. The Mohr Coulomb yield surface is linearised by means of an exterior regular polygon circumscribing the actual failure surface so that the finite element formulation leads to a linear programming problem. In solving the different problems taken in this thesis, computer programs were developed using 'MATLAB' with the usage of 'LINPROG' - a library subprogram for doing the necessary optimization. The bearing capacity factor Ny for an isolated single rigid strip footing placed on a cohesionless ground surface has been computed and its variation with respect to the footing-soil roughness angle (8) has been examined in detail. It is clearly noted that an increase in 8 leads to a continuous increase in Ny. The solution is also obtained for a perfectly rough footing without considering any velocity discontinuity surface along the footing-soil interface. With 5 = <|), the magnitude of NY becomes almost the same as that for a perfectly rough footing. The size of the plastic zone increases with an increase in the values of 8 and <j). The obtained values of Ny for 5=0 and § compare quite favorably with the solutions reported earlier in literature. The ultimate bearing capacity for a group of two and an infinite number of multiple interfering rough strip footings placed on a cohesionless medium has been computed; all the footings are assumed to be perfectly rigid. It is specified that the footings are loaded simultaneously to failure exactly at the same magnitude of the failure load. For different clear spacing (S) between the adjacent footings, the magnitude of the efficiency factor (£,y) is determined. In the case of two footings, the value of E,y at S/B = 0 becomes exactly equal to 2.0, and the maximum ^occurs at a critical spacing (Scr). For S/B < Sor/B, the ultimate bearing pressure for a footing becomes equal to that of an isolated footing having the width (2B+S), and the ground mass encompassed between the two footings deforms mainly in the downward direction. In contrast, for S/B > Scr/B, ground heave is noticed along both the sides of the footing. As compared to the available theories in literature, the analysis presented in this thesis provides generally lower values of ^y for S/B > Scr/B. ' In the case of a group of multiple strip footings, the value of £y is found to increase continuously with a decrease in S/B. The effect of the variation of spacing on §y is found to be very extensive for small values of S/B; the magnitude of ^y approaches infinity at S/B = 0. For all the values of S/B ground heave is invariably observed on both the sides of the footings. The magnitudes of ^Y for given values of S/B and <|) for the two footings case are found to be smaller than the multiple footings case. The vertical uplift capacity of an isolated strip anchor embedded horizontally at shallow depths in sand has been examined; the anchor plate is assumed to be perfectly rigid and rough. The collapse load is expressed in terms of a non-dimensional uplift factor FY, the value of which needs to be known before calculating the failure load for an interfering anchor. The magnitude of Fr is found to increase continuously with increase in both embedment ratio (k) and the friction angle (<|>) of sand. Even though the analysis considers the development of plastic strain within all elements, however, at collapse, the soil mass just above the anchor is found to move as a single rigid block bounded by planar rupture surfaces; the rupture surfaces emerging from the anchor edges are seen to make approximately an angle <|> with the vertical. The vertical uplift capacity of a group of two and an infinite number of multiple interfering rigid rough strip anchors embedded horizontally in sand at shallow depths has been examined. At collapse, it is specified that all the anchors in the group are loaded to failure simultaneously exactly at the same magnitude of the failure load. For different clear spacing (S) between the anchors, the magnitude of the efficiency factor (£Y) is determined. On account of interference, the magnitude of 4y is found to reduce continuously with a decrease in the spacing between the anchors. For all values of X and §, the magnitude of ^y for the multiple anchors case is found to be always smaller than that for the two anchors case. In contrast to a group of footings under compression, the magnitude of ^v for a group of anchors is found to decrease invariably with an increase in $ for a given value of S/B. For S > 2c/tan<j) , the uplift resistance of anchors in the group becomes equal to that of an isolated anchor, and no interference is seen to exist; where d is the depth of anchor. By examining the nodal velocity patterns, it was noted that in the event of collapse, a wedge of soil mass just above the anchors and encompassed within linear rupture surfaces moves vertically upward almost as a single rigid unit with the velocity same as that of the anchor plate itself. On this basis, a closed form solution of the problem has been developed. The results from the closed form solution for the group of two anchors as well as for multiple anchors are found to provide an excellent comparison with the rigorous upper bound numerical solution especially for the value of § greater than or equal to about 35°. For all the problems taken in this study, it has been seen that an upper bound limit analysis in combination with finite elements and linear programming is a very useful numerical tool for determining the magnitudes of collapse loads.

Este projeto tem o objetivo de apresentar o estudo dos arames da armadura de tração que são empregados no transporte de óleo, gás e umbilicais hidráulicos na indústria petrolífera. Este estudo foi desenvolvido sob a necessidade de melhor ancoragem dos arames da armadura de tração de modo a garantir que, mesmo após a ruptura do arame dentro do conector não haverá o escorregamento do mesmo provocando a queda do duto flexível. Assim sendo, foi estabelecido o estudo de aderência da interface dos arames da armadura de tração dos dutos flexíveis. Com os ensaios concluídos se estudou um novo procedimento para o melhoramento de aderência mecânica dos arames com a resina epóxi. Após os ensaios de aderência e adesão concluídos foi realizado ensaio de tração em cada arame da armadura de tração sob sua montagem no conector de extremidade para verificação de carregamento que chegam nos ganchos dos arames da armadura de tração. Os estudos realizados no conector de extremidade de 2,5 demonstram que os ganchos dos arames da armadura de tração são de grande importância para a integridade estrutural do duto flexível, visto que o cone de resina formado dentro do conector não está em contato com toda a área dos arames das armaduras de tração. / This project aims to present the study of tensile armor wires usually employed in the transport of oil, gas and hydraulic umbilicals in the petroleum industry. This study was developed as a need for better anchoring of the tensile armor wires in order to guarantee that even after the rupture of the wire within the connector it will not slip causing the fall of the flexible riser. Thus was established the adhesion study of the interface of the tensile armor wires of the flexible risers. After the end of the tests a new procedure for improving mechanical adhesion between the wires and the epoxy resin was studied. After the end of the adhesion tests tensile test was performed on each wire of the tensile armor under its mounting on the end fitting for checking the loading that reaches the hook of the armor wires. The trials performed in the 2.5end fitting show that the tensile armor wire hooks are of great importance for the structural integrity of the flexible riser, as there is no contact between the resin cone formed within the end fitting and the tensile armor wires area.

Este projeto tem o objetivo de apresentar o estudo dos arames da armadura de tração que são empregados no transporte de óleo, gás e umbilicais hidráulicos na indústria petrolífera. Este estudo foi desenvolvido sob a necessidade de melhor ancoragem dos arames da armadura de tração de modo a garantir que, mesmo após a ruptura do arame dentro do conector não haverá o escorregamento do mesmo provocando a queda do duto flexível. Assim sendo, foi estabelecido o estudo de aderência da interface dos arames da armadura de tração dos dutos flexíveis. Com os ensaios concluídos se estudou um novo procedimento para o melhoramento de aderência mecânica dos arames com a resina epóxi. Após os ensaios de aderência e adesão concluídos foi realizado ensaio de tração em cada arame da armadura de tração sob sua montagem no conector de extremidade para verificação de carregamento que chegam nos ganchos dos arames da armadura de tração. Os estudos realizados no conector de extremidade de 2,5 demonstram que os ganchos dos arames da armadura de tração são de grande importância para a integridade estrutural do duto flexível, visto que o cone de resina formado dentro do conector não está em contato com toda a área dos arames das armaduras de tração. / This project aims to present the study of tensile armor wires usually employed in the transport of oil, gas and hydraulic umbilicals in the petroleum industry. This study was developed as a need for better anchoring of the tensile armor wires in order to guarantee that even after the rupture of the wire within the connector it will not slip causing the fall of the flexible riser. Thus was established the adhesion study of the interface of the tensile armor wires of the flexible risers. After the end of the tests a new procedure for improving mechanical adhesion between the wires and the epoxy resin was studied. After the end of the adhesion tests tensile test was performed on each wire of the tensile armor under its mounting on the end fitting for checking the loading that reaches the hook of the armor wires. The trials performed in the 2.5end fitting show that the tensile armor wire hooks are of great importance for the structural integrity of the flexible riser, as there is no contact between the resin cone formed within the end fitting and the tensile armor wires area.