Experimental Investigation on Strengthening of Bolted Connections in Transmission/Communication Towers

  • R. Balagopal
  • N. Prasad Rao
  • R. P. Rokade
  • P. K. Umesha
Original Contribution


Due to increase in demand for power supply and increase in bandwidth for communication industry, the existing transmission line (TL) and communication towers needs to be strengthened. The strengthening of existing tower is economical rather than installation of new towers due to constraints in acquisition of land. The size of conductors have to be increased or additional number of antenna needs to be installed in existing TL/communication tower respectively. The compression and tension capacity of members in the existing towers have to be increased to sustain the additional loads due to wind and self-weight of these components. The tension capacity enhancement of existing angle sections in live line condition without power shut-down is a challenging task. In the present study, the use of Glass Fiber Reinforced Plastic (GFRP) plate/angle sections is explored to strengthen existing bolted connections in TL/communication towers. Experimental investigation conducted at component level on strengthening of existing two types of single cover steel butt joint, one made of steel plate and another joint made of steel angle sections respectively. First series of experiment conducted on strengthening the connection using GFRP plate/cleat angle sections. The second series of strengthening experiment is conducted using steel plate/angle sections to replace GFRP sections. The load sharing behaviour of strengthened GFRP and steel section is compared and suitable recommendations are given.


Bolted connection Structural upgradation Connection strengthening GFRP Tension capacity enhancement Single cover butt joint 



This paper is being published with the kind permission of The Director, CSIR-Structural Engineering Research Centre, Taramani, Chennai, INDIA. The authors would like to thank all the supporting staff of Tower Testing and Research Station, CSIR-SERC, towards the successful completion of the experiments.


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Copyright information

© The Institution of Engineers (India) 2018

Authors and Affiliations

  • R. Balagopal
    • 1
  • N. Prasad Rao
    • 1
  • R. P. Rokade
    • 1
  • P. K. Umesha
    • 1
  1. 1.Tower Testing and Research StationCSIR-Structural Engineering Research CentreChennaiIndia

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