Influence of strength and durability characteristics on the behaviour of power transmission line supports

Abstract

The electric poles, also called as line supports, act as the main element for transmission and distribution of power supply. These poles made of concrete have to withstand attacks due to chemicals, gases, moisture and other harmful substances as well. They are also to be used in marine environments and coastal zones. In order to suit toall these conditions, and to make the poles much stronger and more durable,the design mix has to be changed with the addition of certain suitable mineral and/or chemical admixtures in specified proportions.In this thesis, load-deflection tests of various sizes of Reinforced Cement Concrete (RCC) poles and Pre Stressed Concrete (PSC) poles used in power sector (State Electricity Boards) have been conducted and analyzed. Further, model reinforced concrete poles have been cast with replacement or addition of fly ash/quartz powder to a certain percentage in place of cement/fine aggregate. The load tests have been carried out on these model poles in order to predict the behaviour of the prototype of the poles, if they are to be cast for adoption in the field. The behaviours of these poles have been compared with the conventional concrete pole to ascertain the benefits of the addition of fly ash/quartz. Further, it is observed that the failure of RCC poles happens mainly because of the corrosion of reinforcements at ground line and hence wrapping shall be adopted to inhibit corrosion and to extend the service life of the poles.The prototypes of PSC poles have been cast with quartz powder, and with additional reinforcements separately to study the influence of these materials in the flexural behaviour. newline