Structural Performance of Circular Pre-stressed Concrete Poles Used In Electric Power Distribution Network

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Structural Performance of Circular Pre-stressed Concrete Poles Used In Electric Power Distribution Network

ارائه دهنده: Provider: Alireza Fekri Monazah

اساتید راهنما: Supervisors: Mostafa Moghadasi (Ph. D)

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Mahmoud Nili (Ph. D) Fereydoun Rezaie (Ph. D)

زمان و تاریخ ارائه: Time and date of presentation: March, 16, 2021

مکان ارائه: Place of presentation:

چکیده: Abstract: The power distribution network is one of the most important infrastructures in any country, and any disruption in it can result in public dissatisfaction. If the disruption in the power distribution network is due to some fault in the power poles, it will take more time and cost to reconnect the power. Concrete poles are one of the most common ones in Iran. Concrete poles are constructed in two forms: H-shaped reinforced concrete and circular pre-stressed concrete. Despite the fact that circular pre-stressed poles are emerging in Iran, some provincial power distribution companies have made the use of this type of pole obligatory. Due to the unknown behavior of pre-stressed poles verses to H-shaped reinforced concrete poles as well as the lack of a clear comparison between the functions of these two types of poles, most power distribution companies still recommend using H-shaped poles. In this study, the factors affecting the structural behavior of pre-stressed poles were examined using numerical studies. Then, the stability of this type of pole in different climatic conditions in distribution lines was investigated. Finally, the structural and economic performance of the pre-stressed poles and that of H-shaped reinforced concrete poles were compared. Model structuring and base analysis were done by ABAQUS software. The pole geometry was done in accordance with the instructions of requirement determination, technical evaluation criteria, and pre-stressed concrete tests. A test of the compressive strength of the concrete and the tensile strength of the rebar for all steels in the pole were run in order to define accurately the characteristics of the materials used in the pole. The lateral tensile test of the pole, which determines the acceptance and rejection of the pole was conducted for the pole. Accordingly, the stages of the same test were exactly simulated in ABAQUS. The outputs of the software analysis were compared with the data obtained from the lateral tensile test of the base to make sure of the software outputs. After the software outputs were verified, the factors affecting the structural behavior of the pole such as the amount of compressive strength of the concrete and the amount of pre-stressing stress of tendons were assessed. In order to examine the stability and instability of the poles in different climatic conditions in a power distribution line, the differential equation was employed. The present study was conducted for the spans of 35 to 80 meters and steps of 5 meters. The results of the lateral tensile test of the pole were used to compare the structural behavior of circular pre-stressed pole with that of H-Shaped reinforced concrete poles. In economical comparison among poles, in addition to the cost of each pole, environmental issues such as carbon dioxide production, water consumption were also taken into consideration. Finally, at the end of the current research, by examining the findings of the analysis, it was found that the behavior of pre-stressed pole is very sensitive to changes in compressive strength of concrete and changes in pre-stressing stress. The higher the compressive strength of concrete above 40 MPa, the better the pole will perform in lateral tensile testing. Changes in pre-stressing stress have little effect on the pole rupture force; However, if the pre-stressing stress is less than 1000 MPa (due to high residual deformation), it will cause the pole to fail in the lateral tensile test. In power distribution lines, the middle poles remain stable in most climatic conditions. However, end poles are more prone to instability due to the unilateral tension of the wires. That's why, it is better to choose end poles with more nominal strength. According to the comparison between the structural behavior of pre-stressed poles and H-Shaped reinforced concrete poles, it was revealed that H-shape poles show more stiffness behavior. Although the cost of pre-stressed pole is higher than that of H-shape one, but advantages such as durability, lower weight, better cross-section as well as some environmental factors have made pre-stressed poles a good alternative to H-shape reinforced concrete poles. Key Words: power distribution network, pre-stressed concrete pole, lateral tensile test of pole, H shaped reinforced concrete pole

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