RELIABILITY ANALYSIS OF PRESTRESSED ELECTRIC TRANSMISSION CONCRETE POLES
RELIABILITY ANALYSIS OF PRESTRESSED ELECTRIC TRANSMISSION CONCRETE POLES
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Date
1997-12
Authors
SHEHU, HADI AHMAD
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Abstract
Reliability and economy are inherently competing demands; the study of which is
becoming an increasing concern for the designers of electric transmission line structures
and more generally to the profession of Structural Engineering. The work covered in this
study deals with the assessment of the reliability (safety) levels of the prestressed electric
transmission concrete poles; as they are used for support of transmission line.
Safety levels at various heights of tappered I - section poles have been investigated for
the serviceability limit states in various categories Viz:- Compressive and Tensile
working stress conditions, deflection requirements and stability criteria. Several
combinations of load and resistance effects are considered and implied safety levels for
this class of poles are estimated.
A general purpose computer program package based on FORM5 (First Order Reliability
Method; Version 5) was adopted for the estimation of the safety levels associated with
the different limit states examined. As far as the serviceability limit states are concerned,
it is found that the requirements for the working stresses in compressive and tensile and
the criteria for deflection and stability are very conservative. In most cases, the critical
points along the poles height fall within the solid rectangular section. It is also noted that
the failure of the poles within the first 1.0 to 1.5m from the apex is quite alarming. The
conditions governing the deflection requirements call for an immediate reappraisal since
the associated safety levels are extremely very low.
The results have been plotted so that the safety level (0) can be read off for any given
limit state condition for a pole at various heights for any load and resistance effects
desired. In addition, the cost-effectiveness of the design requirements for tensile criteria
is also estimated.
Description
A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL, AHMADU BELLO
UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR
THE AWARD OF THE DEGREE OF MASTER OF SCIENCE
(STRUCTURAL ENGINEERING)
DEPARTMENT OF CIVIL ENGINEERING
AHMADU BELLO UNIVERSITY
ZARIA
DECEMBER, 1997
Keywords
RELIABILITY,, ANALYSIS,, PRESTRESSED,, ELECTRIC,, TRANSMISSION,, CONCRETE POLES