34 m high tower design to the Eurocodes

[nivoo_boss]

Hey everyone!

There's a possibility I'm going to have to design a tower as shown in the picture below this year. The tower is about 34 m high and the cross-section is about 6x6 m.

I'm quite scared since I haven't designed towers before, but thankfully at least I'm most experienced with the design of steel structures and the tower is all steel. Are you aware of any guides that might help here? What are the main differences here compared to let's say some more common buildings - fatigue, natural frequencies of the tower etc? I work with Eurocodes.

 

[centondollar]

Foundation is probably important. Towers like that can be designed as cantilevers; the tower is a sway-frame globally and a truss or frame (or a mix of both) in the local (strength) analysis.

Natural frequencies may be computed by FEA, and cross-checked by a lumped mass model (say- one or two discrete masses per "floor") and hand-calculation. Fatigue should not be an issue, unless the wind causes a load that often exceeds the theoretical "infinite fatigue life" cyclic stress amplitude value. Since the tower does not seem to have any facade elements, it will not pick up a lot of wind - most of it will flow through the empty space between the members.

 

[human909]

It is fairly straight forward in my experience. In my experience with those dimensions your tower should end up stiff enough to not need too much thought and analysis into the complexities of wind and vibration. (Though I'd welcome disagreement with my assessment!)

Though given the nature of your tower (observation/viewing tower) its position might mean more complicated wind dynamics than normal.