Introduction
In this case, the high-tension wires will be supported by slender steel conical towers. The towers are loaded by various horizontal and vertical load components.
The following load mechanism can be distinguished:
- Wind is an important load component both from a static and a dynamic perspective. The wind load acts directly on the tower but also indirectly through the high-tension wires.
- Loads by the mechanical tension in the high-tension wires. The tension wires produce local loads at the wire fixations but also exercise unbalanced loads on the towers at changes in the direction of the tension wire routing.
- Further, the towers will be loaded locally by various additional clips (some of them relatively highly loaded). The clips are welded to the tower to support help rails, lightning protection wires, and guy wires.
The required access door to the tower inside located at the foot of the tower (the highest loaded cross-section) is an additional complication in the analysis.
Analysis
Based on the specified load cases for the tower from a structural integrity perspective, the most critical items and corresponding load conditions were made.
Almost all analyses were static analyses except for the wind assessment. For the wind impact, an analysis conforming to the Eurocode 1 was performed. In this type of analysis, the dynamic properties of the tower were taken into account. In most of the analyses, Finite Element models have been used.
“The wind load acts directly on the tower but also indirectly through the high tension wires.”
Results
- The calculations that have been performed demonstrate that the access door portal for the tower needs substantial reinforcement to keep the local stresses below the project-defined acceptable material stress.
- Upon implementation of the applicable reinforcement to be satisfactory the calculations that were performed demonstrate both stress and deflection, in regards to the fitness for the tower and defined the load conditions.
