Development of method for calculation of pre-strained steel cylindrical sheaths in view of the winding angle, pitch and thickness

Abstract

This paper sets out the findings of an investigation on the development of a method for calculating aboveground pre-strained cylindrical sheaths, in view of design parameters: the winding angle, pitch and thickness on a concrete base, as a result of which a new expression was obtained. The analysis of the obtained expression showed that the winding thickness variation from 4 mm to 6 mm at the angle of helix of 90º, the value of the strained state parameter (k) varies from 1.3 % to 4.64 %, similar increases in the value of k were obtained with an increase in thickness and at angles of helix of 60º and 75º, where the value of k increased by 0.94–3.82 % and 1.12–4.56 %, respectively. The findings also showed that as the winding thickness increases, the value of k increases independently at different winding angles and pitches. A similar analysis was performed with a variation in the pitch, but with respect to the winding thickness and angle, where the value of k also varies in terms of the winding pitch ranging from 2.61 % to 18.59 % depending on the specific case, and the analysis of the angle of helix showed a variation in the value of k ranging from 0.37 % to 5.24 %. The findings of the variant analysis showed the practicality of the expression obtained, which affords ground for obtaining the required value of the strained state parameter for a particular specific case without carrying out lengthy calculations, which may explicitly supplement the investigations formerly pursued in this course.

Keywords

• Prestress
• Concrete base
• Aboveground cylindrical shells
• Calculation method
• Wrapping
• Winding thickness