Numerical investigation on the effect of member orientation to the strength of transmission tower
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Date
2019-06
Authors
Karen Yong Bee En
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Abstract
Transmission tower is made up of angle sections that are connected eccentrically
by one leg of the section. Generally, commercial software automatically generates the
connection of the member as concentric. This type of modelling ignores the actual
orientation of the tower members. The eccentric connection may increase the internal
forces and need to be investigated. In this study, numerical model of 132 kV transmission
tower was generated and analysed with the aid of STAAD Pro. V8i commercial software.
The aim is to investigate the change in the member forces and used capacity of main
tower members due to eccentric connection. Two types of models were developed to
differentiate the members with concentric and eccentric connection. In addition, normal
loading condition and another three sets of broken wire conditions were applied to all
models. The differences in the member axial forces were calculated and discussed
accordingly. The results showed that the axial force in the main members increased under
normal loading condition when the wind direction was applied in x-axis. Compared to
normal loading condition, models with broken wire condition showed higher increase in
the axial forces due to eccentric connection. In addition, the highest percentage
differences in terms of maximum compressive force between concentric and eccentric
connection was developed in (G.W) broken wire condition subjected to wind in x-axis.
Moreover, one of the members located on the tower cage failed when subjected to (T.C
+ M.C) broken wire condition. In this case, the used capacity was exceeded by 6.82%.
The significant increase in the internal member forces and possible failure of tower
member due to eccentric member connection suggests that the actual orientation of the
tower members must be considered in the design of transmission towers.