Structural Modelling and Analysis of Double Circuit Lattice Power Transmission Tower Subjected to Blast Load
No Thumbnail Available
Date
2020-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
A study on the effects of blast loads on tower-line coupling, single tower structure and
tower-line structure system has been conducted and a variety of structural response
variables have been compared. Time history analysis has been carried out by considering
different charge blast parameters and stand-off distances. Various combinations of charge
weights and stand-off distances have been considered both on coupled- and uncoupled
tower arrangements along with detailed study of the effects of conductor coupling during
the analysis modeling and subsequent design of transmission towers.
The modular and powerful finite element analysis software Dlubal-RFEM has been
utilized for the blast-oriented linear implicit dynamic analysis of latticed transmission line
structures covered in this study. The transient dynamic equilibrium equations of the tower
have been directly solved by Newmark time integration method. The various internal
forces, displacements and a variety of dynamic response behaviors have been isolated,
recorded and compared for a single tower and tower-line coupled systems under different
charge weight and stand-off scenarios. When numerically modeling and analyzing the
structure, both coupled and uncoupled tower-line arrangements, three-dimensional natural
vibration analysis has been taken into account.
Findings from numerical experiences on several analysis models have indicated that the
tower-line coupling system significantly influences the response of tower structures with
particular significance on tower supports. Current design codes and guidelines have few,
if any, methods or recommendations to deal with power transmission towers subjected
to blast loads and, when they do exist, they do not comprehend corresponding tower-line
coupled effects. The study has indicated that internal forces in members of uncoupled
towers are generally larger than the corresponding values in coupled systems. The main
difference arises in the support reactions. Several study models from this work have
indicated that there is up to nearly four-fold increase in support forces in uncoupled
systems which subsequently greatly influence the planning, selection, design and detailing
of support systems for such structures. Thus, the study has revealed the fact that
establishing support forces by considering a single uncoupled tower will lead to
underestimating critical loads. When designing such structures, coupling effects should be
incorporated in the analysis process.
Description
Keywords
Double Circuit Lattice Power, Power Transmission Tower, Blast Load