Sign and signal structures involved in vehicular accidents are often partially damaged, and it is possible to repair them instead of replacing them, even when the extent and severity of the damage are substantial. The replacement of these poles is costly and involves interruption for pedestrians and traffic. Therefore, some trials were performed to retrofit these poles in-situ with low cost and short time. Previous research has substantiated that the damage can decrease the strength of the these structures with increasing the dent depth and the use of externally-bonded fiber-reinforced polymer (FRP) composites are beneficial to repair them. The composite systems were comprised of glass or basalt fibers paired with epoxy or polyurethane matrices. The effectiveness of FRP in repairing the damaged poles was demonstrated in previous tests on dented poles using 3-point, 4-point, and cantilever bending tests. The repair systems were able to develop the load carrying capacity of the damaged poles, and their behaviors were controlled by various types of failure modes like yielding of the metallic substrate, FRP tensile rupture, FRP compressive buckling, and debonding of FRP from the substrate. This thesis investigates the resistance of repaired full-scale metallic poles retrieved from the field for monotonic, cyclic, and impact loading. These poles, which have rounded and multi-sided cross sections with and without access ports, were dented in the field or dented mechanically in the laboratory and repaired with the same repair systems mentioned previously. Six of these poles were mounted horizontally in a cantilever configuration to test them monotonically, while three of them were tested cyclically. In both tests, the load was applied as a point load at 9 ft from the base plate. Additionally, two poles were mounted vertically using a cantilever configuration to test them for impact. This test was performed by hitting the poles using an impact pendulum with a 1100 kg mass.The results of static tests show that the repair systems failed because of the aforementioned failure modes. However, most of the failure was located outside the dented region, which indicates the effectiveness of these repair systems in restoring the capacity of the damaged area. During the fatigue tests, the repair experienced no damage before weld rupture in the original steel tube-base plate connection. Moreover, the repair systems proved their effectiveness in resisting the impact load, because they were ruptured at the contact region between the pole and the impactor at the time the poles were deformed at the free side of the poles, as well as the impact side, during the test. In all these tests, the access ports affected the behavior of the repaired poles. Depending on the geometry of the pole, metal substrate, and dent depth and location, FRP repair system recommendations will be presented.

Submitted as the dissertation component in partial fulfillment of the requirements for the Masters Diploma in Technology (Electrical engineering - heavy current), Electrical Engineering, ML Sultan Technikon, 1998. / The use of pre-stressed concrete poles for the Inwabi Plateau rural distribution line has presented unforseen problems for the Durban Electricity Service Unit, such as poor line performance and structural damage to the poles. The effects are thought to be due to lightning. This dissertation deals with an investigation into the cause of the damage as well as recommendations regarding the repair and prevention of future damage. To achieve this, an evaluation of the line Basic Insulation Level (B.I.L.) together with a review of the existing literature on the effects of lightning to overhead lines was used in order to establish what the specific damage mechanisms are. Field and laboratory tests were also undertaken as part of the investigation. Based on the results obtained, the overhead line was modified in terms of it's B.I.L. A preliminary evaluation of the modifications was done, with recommendations regarding further work to be done in the future. / M

We use the behavioural approach and commutative algebra to define and characterize poles and zeros of multidimensional (nD) linear systems. In the case of a system with a standard input output structure we provide new definitions and characterizations of system, controllable and uncontrollable zeros and demonstrate strong relationships between the controllable poles and zeros and properties of the system transfer matrix, and we show that the uncontrollable zeros are in fact uncontrollable poles. We also show that we can regard the zero as a form of pole with respect to an additional form of input output structure imposed on the zero output sub-behaviour. In the case when the behaviour has a latent variable description we make a further distinction of the zeros into several other classes including observable, unobservable and invariant zeros. In addition we also introduce their corresponding controllable and uncontrollable zeros, such as the observable controllable, unobservable controllable, invariant controllable, observable uncontrollable, unobservable uncontrollable and invariant uncontrollable etc. We again demonstrate strong relationships between these and other types of zeros and provide physical interpretations in terms of exponential and polynomial exponential trajectories. In the 1D case of a state-space model we show that the definitions and characterizations of the observable controllable and invariant zeros correspond to the transmission zeros and the invariant zeros in the classical 1D framework. This then completes the correspondences between the behavioural definitions of poles and zeros and those classical poles and zeros which have an interpretation in nD.

Wood crossarms provide an efficient economical, structural, and sustainable solution to the distribution and transmission of electric utilities. The majority of these crossarms are made from two species of wood, Douglasir (Pseudotsuga menziesii) and southern pine (Pinus spp.). In this study 210 solid-sawn wood crossarms (120 pieces of Douglasir/ 90 pieces of southern pine) were evaluated with non-destructive (NDTs) and destructive testing to determine if NDT could be used to predict crossarm performance. Three NDTs were conducted. Subsequently, destructive testing in which each specimen was broken in accordance to ASTM D-198 for modulus of elasticity (MOE) and modulus of rupture (MOR) was performed. After testing each specimen the non-destructive data was compared to the destructive testing results by mean comparisons and correlations. In this study it was found that the E-computer (NDT) produced the strongest correlation in both species to destructive values, especially MOE.

<p> This paper is a general examination of the applicability of the growth pole and the growth center concepts to development planning in underdeveloped nations. It is found that, because of the problems which are unique to each concept and the characteristics which are unique to each economic setting, the notions are not generally applicable. Analysis also suggests that the prime factor determining the success or failure of any development strategy is the political environment of the host country. The future does not appear to be particularly bright, due to the lack of progress with these growth notions and the existence of no real alternatives, and due to the political and institutional inertia prevalent within underdeveloped nations.</p> / Thesis / Bachelor of Arts (BA)

This research investigation studied the effects of galvanization on the fatigue life of high mast illumination poles. Reports that galvanization of high masts caused initial cracks to form at the toe of the weld connecting the base plate to the shaft of the pole were first validated. The effects of these initial cracks on fatigue strength were then checked through experimental testing. A variety of variables were tested for both their effects on the occurrences of the initial cracks and effects on fatigue life. These variables included testing galvanized against ungalvanized specimens, testing of varying fabricators and galvanizers, and testing of various types of connection details. These test results were compared against inspection results provided by Texas Department of Transportation inspectors. Also, methods of mitigating the effects of toe cracks on the fatigue life of poles were investigated. A method for repairing specimens both in the fabrication shop and in the field were developed and tested. Both methods showed strong improvement in fatigue life of the specimens providing a possible repair solution. / text

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Wood is one of the oldest and most common material used in construction. Since the beginning of the electrification in Canada in late 19th-century, wood poles have been widely used to provide structural support to electric transmission and distribution lines. For example, electrical network in Ontario has over 2 millions distribution poles across the province. Wood poles are typically exposed to severe environmental conditions, which cause deterioration due to wood rotting, insect attack, and weathering. The wood deterioration resulting in loss of strength can compromise the structural integrity of poles. Typical life expectancy of wood varies from 35 to 50 years depending on the environmental condition and type of wood. Electrical distribution infrastructure in Canada is aging. For example, the average age of in-service wood poles in Ontario is estimated to be 29 years with a standard deviation of 15 years. About 300,000 wood poles have been in-service for more than 45 years, which are rapidly reaching to end of expected service life. Different types of non-destructive testing (NDT) methods have been historically used for the condition assessment of wood poles. However, current methods are based on simple concepts that do not consider the variations of wave velocity and wave attenuation in an orthotropic material. The goal of this research investigation is to develop an advanced and reliable NDT technique for in-situ inspection and assessment of wood poles in order to remove unsafe poles from service, extend the service life of sound poles, and support optimum replacement strategies for the renewal of wood pole infrastructure. The thesis presents a new methodology for condition assessment of wood poles using ultrasonic testing based on theoretical, numerical, and experimental studies. The research covers areas such as signal processing, dynamic characterization, statistical reliability analysis, numerical simulations, and laboratory testing. Wood is modeled as a cylindrical orthotropic material with uncertainties in its elastic and mechanical properties. The arrival time of compressional waves as well as full-waveform analysis are used for an integrated evaluation of wood pole. A simplified model of P-wave propagation in pole cross-sections is developed; which allows to (a) estimate the elastic moduli in the radial and tangential directions by solving the inverse problem, and (b) compute the probability density function of P-wave velocity. Both of these parameters are critical for condition assessment; however, they are not available in the literature because of the complexities associated with modelling wood as an orthotropic material. A new specialized software is developed for (a) general signal processing, (b) non-destructive condition assessment of wood poles, and (c) management of a statistical database for the assessment of wood poles. Based on the proposed methodology, a new clamping device is designed and built for the ultrasonic testing of wood poles in the field. The basic background for signal processing covering Fourier analysis, frequency response and impulse response functions, and the complex exponential method for dynamic system identification is reviewed and summarized. The elastic and mechanical properties for most common species of wood used as poles are summarized from the literature, including the main statistical distributions used for their probabilistic characterization. The calibration and basic assumptions for the simulation of wave propagation in orthotropic media using finite element analysis are explained in detail. Numerical modelling is based on finite element method under plain strain condition. The numerical model is calibrated using theoretical results and validated using experimental results from laboratory testing of a new red pine pole. After calibrating the model, numerical simulations were performed to understand ultrasonic wave propagation in cross-sections of sound and decayed wood poles sections. Results of numerical simulations of ultrasonic wave propagation in pole cross-sections are presented. The effect of a void in the cross section on the ultrasonic measurement is discussed. A sample of 8 wood pole cross-sections were subjected to laboratory ultrasonic tests. In the testing, a transmitter was placed at four positions around the pole circumference. For each transmitter position, five receivers were used. The transmitter-receiver system was calibrated to evaluate its transfer function and thus eliminate the inherent characteristics of the transmitter-receiver system from the actual measurements. The experimental results of the condition assessment of new and decayed pole samples are presented in the thesis. The effect of a hole in a new pole was studied and the results were compared with the numerical analysis. A blind test is performed on an aged red pine pole. The predicted areas of decay from the ultrasonic measurements are in good agreement with the actual decay observed from dissecting the pole sections. In summary, the experimental and numerical results presented in this thesis show that the proposed methodology can be successfully applied for condition assessment of in-service wood poles in the electrical network. This method will contribute to cost-effective life cycle management of energy infrastructure as a whole.

Wood is one of the oldest and most common material used in construction. Since the beginning of the electrification in Canada in late 19th-century, wood poles have been widely used to provide structural support to electric transmission and distribution lines. For example, electrical network in Ontario has over 2 millions distribution poles across the province. Wood poles are typically exposed to severe environmental conditions, which cause deterioration due to wood rotting, insect attack, and weathering. The wood deterioration resulting in loss of strength can compromise the structural integrity of poles. Typical life expectancy of wood varies from 35 to 50 years depending on the environmental condition and type of wood. Electrical distribution infrastructure in Canada is aging. For example, the average age of in-service wood poles in Ontario is estimated to be 29 years with a standard deviation of 15 years. About 300,000 wood poles have been in-service for more than 45 years, which are rapidly reaching to end of expected service life. Different types of non-destructive testing (NDT) methods have been historically used for the condition assessment of wood poles. However, current methods are based on simple concepts that do not consider the variations of wave velocity and wave attenuation in an orthotropic material. The goal of this research investigation is to develop an advanced and reliable NDT technique for in-situ inspection and assessment of wood poles in order to remove unsafe poles from service, extend the service life of sound poles, and support optimum replacement strategies for the renewal of wood pole infrastructure. The thesis presents a new methodology for condition assessment of wood poles using ultrasonic testing based on theoretical, numerical, and experimental studies. The research covers areas such as signal processing, dynamic characterization, statistical reliability analysis, numerical simulations, and laboratory testing. Wood is modeled as a cylindrical orthotropic material with uncertainties in its elastic and mechanical properties. The arrival time of compressional waves as well as full-waveform analysis are used for an integrated evaluation of wood pole. A simplified model of P-wave propagation in pole cross-sections is developed; which allows to (a) estimate the elastic moduli in the radial and tangential directions by solving the inverse problem, and (b) compute the probability density function of P-wave velocity. Both of these parameters are critical for condition assessment; however, they are not available in the literature because of the complexities associated with modelling wood as an orthotropic material. A new specialized software is developed for (a) general signal processing, (b) non-destructive condition assessment of wood poles, and (c) management of a statistical database for the assessment of wood poles. Based on the proposed methodology, a new clamping device is designed and built for the ultrasonic testing of wood poles in the field. The basic background for signal processing covering Fourier analysis, frequency response and impulse response functions, and the complex exponential method for dynamic system identification is reviewed and summarized. The elastic and mechanical properties for most common species of wood used as poles are summarized from the literature, including the main statistical distributions used for their probabilistic characterization. The calibration and basic assumptions for the simulation of wave propagation in orthotropic media using finite element analysis are explained in detail. Numerical modelling is based on finite element method under plain strain condition. The numerical model is calibrated using theoretical results and validated using experimental results from laboratory testing of a new red pine pole. After calibrating the model, numerical simulations were performed to understand ultrasonic wave propagation in cross-sections of sound and decayed wood poles sections. Results of numerical simulations of ultrasonic wave propagation in pole cross-sections are presented. The effect of a void in the cross section on the ultrasonic measurement is discussed. A sample of 8 wood pole cross-sections were subjected to laboratory ultrasonic tests. In the testing, a transmitter was placed at four positions around the pole circumference. For each transmitter position, five receivers were used. The transmitter-receiver system was calibrated to evaluate its transfer function and thus eliminate the inherent characteristics of the transmitter-receiver system from the actual measurements. The experimental results of the condition assessment of new and decayed pole samples are presented in the thesis. The effect of a hole in a new pole was studied and the results were compared with the numerical analysis. A blind test is performed on an aged red pine pole. The predicted areas of decay from the ultrasonic measurements are in good agreement with the actual decay observed from dissecting the pole sections. In summary, the experimental and numerical results presented in this thesis show that the proposed methodology can be successfully applied for condition assessment of in-service wood poles in the electrical network. This method will contribute to cost-effective life cycle management of energy infrastructure as a whole.