Lattice pattern of electricity pylons in Belgium

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Toliman
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Lid geworden op: 28 apr 2020 01:47

Lattice pattern of electricity pylons in Belgium

Bericht door Toliman » 31 mar 2023 01:39

Why do some large electricity pylons like EA219-10N ( picture: https://www.hoogspanningsforum.com/down ... p?id=29004 ) have an other lattice pattern as the common pattern used for nearly most other pylons in the world. I know that this extraordinary lattice pattern can be also found at radio towers and flare towers in Belgium and I know it can be also found in the United Kingdom.
Which is the designation of this pattern? Who invented it? Which advntages and disadvantages does it have?

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CS
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Lid geworden op: 09 jan 2017 23:30
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Re: Lattice pattern of electricity pylons in Belgium

Bericht door CS » 17 jul 2023 18:57

Dear,
This is used in Belgium for higher that normal standard towers, +150m. The reasons are:
a. Less wind drag due to the big holes
b. Less weight because you avoid the need of long (heavy) crossing diagonals

The tower on the picture is 176m high and secures a harbour container dock crossing of 800m. They were developed in 1999-2000 in competition with a German SAG design (similar to Elbe crossing). This present design won the bidding, out of other, due to there light weight design of 250ton compared with the 400ton of the boxed design of SAG.

The resemblance with radio towers and flare towers is logical in a way that these kind of high towers are mainly (up to 80%) designed in function of the wind loadings. Conductor load represent in the under legs less that 20% of the loads, which means that the design loads are similar radio and flare towers that are generally also rather high.

The biggest disadvantage of this design is that you need to have high grade designing offices as whatever eccentricity could result in local stress concentrations due to the induced flexion stresses which are difficult (or most of time impossible) to compensate by reinforcement as their is lack of space and support (the middle section is open space)

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