ANALYSIS OF TELECOMMUNICATION TOWERS USING THE STIFFNESS METHOD.

Abstract

It has been observed that most of the telecommunication towers being erected in Nigeria now by the GSM operators are the free standing type with various types of lattice arrangement of the internal bracing members. In this paper, we explore the powerful tool offered by the stiffness matrix method in conjunction with computer-aided solution to conduct the Structural stability analysis of two types of lattice arrangement of telecommunication towers: the triangular and the cross lattice arrangements. A computer model using Structural Analysis Programme SAP-2000 was developed to carry out the analysis.

As a demonstration problem, a 40m high telecommunication free standing tower was analysed for the two different arrangements of the Internal bracing members at wind speeds which were varied between 15m/s and 120m/s. Results of the analysis confirm the presence of significant overturning moments, shaft up-lift and axial forces at the base of the towers. The analysis also revealed the deflection pattern at the top of the towers.

It was interesting to observe that for the same level and magnitude of wind load, the cross lattice arrangement of internal bracing members proved to be more stable than the triangular arrangement as it was discovered that the axial forces induced in the members, the overturning moment at the base as well as the deflection at the top of the tower were generally less in the former than in the latter. It is therefore recommended that for more effective and stable free standing telecommunication towers, the cross lattice arrangement of internal bracing members should be preferred to the triangular lattice arrangement.