Behaviour of masts subjected to action of wind load

1. Chstruct.

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Steel Res. Vol. 46, Nos. l-3, pp.467. papernumber 194, 1998 01998 Elsevier Science Ltd. All rights reserved Printed in Great Britain 0143-974X/98 $19.00 + 0.00 PII: 50143-974X(98)00132-6

Behaviour of Masts Subjected to Action of Wind Load J. Juozaitis

and A. Sapalas

Department of Steel and Timber Structures, Vilnius Gediminas Technical University, SaulCtekio al. 11, Vilnius, 2040-LT, Lithuania Paper Number 194 Full paper on enclosed CD-ROM

The paper deals with the problems of displacements of radio and TV masts. Horizontal displacements occurring due to action of wind loads have serious influence on the behaviour of structures. Precise determination of displacements is a rather complicated problem because of guy ropes which are treated as elastic supports of changeable stiffness. The magnitudes of these depend on a large number of factors such as cross-section, magnitude of elasticity modulus of guy ropes, level of their prestressing, inclination angle, etc. Among important phenomena it is necessary to note the fact that in certain cases even negligible variation of wind direction causes very significant changes of displacements. This phenomenon is known as “dynamic impact” and has influence not only on behaviour of the structure but is also not desirable from a radio engineering view-point. The main goal of investigations was to determine the horizontal displacements of mast trunk under action of wind load from different directions. The curves expressing the general shape of displacements of node at which guy ropes are connected to the mast trunk, the relationship among displacements, wind direction, diameter of guy ropes and their prestressing level, the character of increments of displacements compared with displacements when wind acts in the guy rope plane are presented in the article. Results of the paper may be useful for primary steps of design when some variants of project are prepared and for evaluation of P - A effect on the last step of design. 0 1998 Elsevier Science Ltd. All rights reserved

KEYWORDS Mast, guy rope, wind load, elastic support, prestressing level, displacement.