• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.9
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• pp.35-44
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• 2014

This study was to secure the safety of poor appearance distribution concrete poles effectively and to reduce the replacement costs of them by developing a soundness evaluation index. The researcher of this study investigated poor appearance types of concrete pole, collected 53 of test samples, and tested pole strength. As a result of strength test, only 17 percent of poor appearance concrete poles were below 2.0 of safety factor spec. As results of multiple regression analysis, it is verified that surface air void, horizontal crack, net-shaped crack, elapsed year, vertical crack, and deterioration in concrete compressive strength have statistically negative effects on safety factor of concrete poles in a significant level. The researcher set up a soundness evaluation index by using multiple regression equation, and suggested that poor appearance concrete poles should be replaced or reinforced only in case of soundness evaluation score of 150 or above.

• Wind and Structures
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• v.29 no.5
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• pp.339-359
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• 2019

Pre-stressed concrete poles are among the supporting systems used to support transmission lines. It is essential to protect transmission line systems from harsh environmental attacks such as downburst wind events. Typically, these poles are designed to resist synoptic wind loading as current codes do not address high wind events in the form of downbursts. In the current study, the behavior of guyed pre-stressed concrete Transmission lines is studied under downburst loads. To the best of the authors' knowledge, this study is the first investigation to assess the behaviour of guyed pre-stressed concrete poles under downburst events. Due to the localized nature of those events, identifying the critical locations and parameters leading to peak forces on the poles is a challenging task. To overcome this challenge, an in-house built numerical model is developed incorporating the following: (1) a three-dimensional downburst wind field previously developed and validated using computational fluid dynamics simulations; (2) a computationally efficient analytical technique previously developed and validated to predict the non-linear behaviour of the conductors including the effects of the pretension force, sagging, insulator's stiffness and the non-uniform distribution of wind loads, and (3) a non-linear finite element model utilized to simulate the structural behaviour of the guyed pre-stressed concrete pole considering material nonlinearity. A parametric study is conducted by varying the downbursts locations relative to the guyed pole while considering three different span values. The results of this parametric study are utilized to identify critical downburst configurations leading to peak straining actions on the pole and the guys. This is followed by comparing the obtained critical load cases to new load cases proposed to ASCE-74 loading committee. A non-linear failure analysis is then conducted for the three considered guyed pre-stressed concrete transmission line systems to determine the downburst jet velocity at which the pole systems fail.

• Structural Monitoring and Maintenance
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• v.9 no.1
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• pp.29-42
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• 2022

In mountainous areas of China, concrete poles with connectors are widely employed in power transmission due to its convenience of manufacture and transportation. The bearing capacity of the poles must have degenerated over time, and most of the steel connectors have been corroded. Carbon fiber reinforced polymer (CFRP) offers a durable, light-weight alternative in strengthening those poles that have served for many years. In this paper, the bearing capacity and failure mechanism of CFRP sheet strengthened existing reinforced concrete poles with corrosion steel connectors were investigated. Four poles were selected to conduct flexural capacity test. Two poles were strengthened by single-layer longitudinal CFRP sheet, one pole was strengthened by double-layer longitudinal CFRP sheets and the last specimen was not strengthened. Results indicate that the failure is mainly bond failure between concrete and the external CFRP sheet, and the specimens fail in a brittle pattern. The cross-sectional strains of specimens approximately follow the plane section assumption in the early stage of loading, but the strain in the tensile zone no longer conforms to this assumption when the load approaches the failure load. Also, bearing capacity and stiffness of the strengthened specimens are much larger than those without CFRP sheet. The bearing capacity, initial stiffness and elastic-plastic stiffness of specimen strengthened by double-layer CFRP are larger than those strengthened by single-layer CFRP. Weighting the cost-effective effect, it is more economical and reasonable to strengthen with single-layer CFRP sheet. The results can provide a reference to the same type of poles for strengthening design.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.49-55
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• 2010

Many electric poles in the softground have been collapsed due to external load. In this study, 10 types of tests were performed with variation of location, numbers and depths of anchor blocks as well as depth of poles to find stresses acting on concrete electric poles. The stresses of concrete poles are relaxed at 600~700[kg] of tensile load, and stresses are concentrated at top of pole, and spread to lower part of pole. In the concrete pole collapse test, tensile load at failure was approximately 1,400[kg], which is twice of design load. As passive zone in the soil increases, the stresses acting on concrete pole are concentrated at lower part of pole based on moment arm earth pressure distribution.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.5
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• pp.42-49
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• 2009

The effects of various forces acting on concrete pole are analyzed using finite element method how the forces affect on ground displacement. The soil types, wind load location of anchor block embedded depth of pole, and distance between poles are varied to find out effects on lateral displacement. Anchor block is effective when it is located at 1/4 of embedded depth The displacement is decreases as elastic modulus increases. Concrete reinforcement for loosened ground is necessary for double poles because double poles cause large excavation. When embedded depth ratio decrease, lateral displacement increase as closer to ground surface. Large embedded depth is effective to reduce lateral displacement, and the distance between poles is not much large factor.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.6
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• pp.237-244
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• 2023

This study analyzes the seismic response of traffic light poles, considering soil-foundation effects through nonlinear static and time history analyses. Two poles are investigated, uni-directional and bi-directional, each with 9 m mast arms. Finite element models incorporate the poles, soil, and concrete foundations for analysis. Results show that the initial stiffness of the traffic light poles decreases by approximately 38% due to soil effects, and the drift ratio at which their nonlinear behavior occurs is 77% of scenarios without considering soil effects. The maximum acceleration response increases by about 82% for uni-directional poles and 73% for bi-directional poles, while displacement response increases by approximately 10% for uni-directional and 16% for bi-directional poles when considering soil-foundation effects. Additionally, increasing ground motion intensity reduces soil restraints, making significant rotational displacement the dominant response mechanism over flexural displacement for the traffic light poles. These findings underscore the importance of considering soil-foundation interactions in analyzing the seismic behavior of traffic light poles and provide valuable insights to enhance their seismic resilience and safety.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1164-1169
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• 2014

Overturning of concrete poles are occurred annually due to natural disaster such as a typhoon. The present code for the resisting moment and the safety on overturning of concrete poles in inclined ground is inadequate. In this study, the concept of the code for those in flat ground is applied to calculate the resisting moment in inclined ground using general analysis program L-Pile Plus13.8. According to the analytical results, the resisting moment in inclined ground is rapidly decrease as increasing the slope angle although the embedded depth are added by the additional embedded depth on the code. It is revealed that the capacity in inclined ground is equivalent to that in flat ground if additional embedded depth is increased from 1.5 to 3 times.

• Advances in concrete construction
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• v.5 no.4
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• pp.391-405
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• 2017

Cement acts as the most important component of concrete as it binds and holds the concrete together. But it is one of the major $CO_2$ emitters all over the world, during manufacturing (900 kg of $CO_2$ per 1000 kg). Some of the modern construction methods aim at reducing the amount of usage of cement and came out with numerous solutions for replacement of the same. One such supplement in current trend is the Steel dust or the Electric Arc Furnace Dust (EAFD), which is a waste product from the electric arc furnace when the scrap metal is melted. When the concrete containing steel dust is exposed to atmosphere, the environmental oxygen and moisture play role to form rust and ultimately the member becomes harder. As Cement is the binder of conventional concrete, only certain percentage of the same could be replaced by the new material, steel dust. Tests were conducted for the 28 days cube strength of M45 grade (suitable for prestressing) concrete which has 0%, 10%, 20%, 30%, 40% and 50% steel dust instead cement. From the test, the optimum percentage replacement of steel dust was obtained, for which the beams and overhead poles were cast, prestressed and tested for the failure load and deflections. A conventional concrete beam and overhead pole were also cast, prestressed and tested to compare the results with those of the beam and pole that contained steel dust. The load vs. deflection plot and other results from the test is also discussed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.183-188
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• 2004

A method of double-pole construction is developing to strengthen the mechanical intensity of the electric poles. Therefore the mechanical properties of the double-pole were researched in this paper. First, considering field special quality electric poles were established. In the next tensile force was applied and stress distribution and fatigue load were examined. When a base of the pole is concrete, mechanical intensity of the double-pole increased about 1.7 times compared a single pole. In the case of general soil base, the concrete base should be needed to expect the reinforcement effect of the double-pole.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1858-1860
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• 2003

Ground rods as the discharge path are commonly installed to ensure the safety of human beings and facilities from the surge. Accordingly, proper grounding resistance are specified by the grounding types, and the specified resistance are also required to install the lightning protective facilities. it is needed to analyze the difference between these two resistance through the field test. Therefore, in this paper, the impulse response behavior of the ground rods is analyzed by constructing the test facilities and by testing the ground rods in multi-ground power distribution systems. The impulse responses were analyzed, in transient state, by testing the concrete poles as well since the grounding wires are installed in the concrete poles.