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jfanning
#1 Posted : 17 April 2014 12:01:26(UTC)
jfanning

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In the submission content it states that we must demonstrate consideration of the dynamic behaviour of the structure. Does this mean we have to carry out a mathematical analysis?

If so can the structure be simplified to a calculation of the fundamental frequency by using the stiffness of the steel and the mass of the structure in each direction?
David Brown
#2 Posted : 17 April 2014 12:08:14(UTC)
David Brown


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Hi

The primary concern is the floor beams, or anywhere that people may go and feel vibration. Perhaps one would say that there will be no-one sleeping there, or no-one sitting at desks that would feel anxious. Perhaps one might expect a bit of movement at the crows nest level?

So the consideration was really about floors, not the overall structure. A simple assessment would be fine - its not a hospital where vibrations would be very important.

A "consideration" could range from a comment that 'its not a problem' (which is not very convincing) to a check of frequency (which is more convincing) with an argument about how the structure will be used.

But its floors, really.

David
jfanning
#3 Posted : 17 April 2014 13:12:28(UTC)
jfanning

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If we have have kept the multi-storey structure separate from the structure which supports the external facade, can we say that due to the lack of dynamic wind loading on the multi-storey can we just analyse the floor beams natural frequency for visitors walking on them?

Also if the crows nest is supported by the same structure as the external facade do we just analyse the movement of the walkway due to the movement of people as well as the wind loading using the stiffness on the members which connect it to this structure ?
David Brown
#4 Posted : 17 April 2014 13:26:38(UTC)
David Brown


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I don't think the seagulls care about how much the ship's cover moves, so just consider the multi-storey part and what the humans feel in the space. Yes, its only dynamics due to walking that we are concerned about. Not wind in this case.

The crows nest is rather different. I think visitors will expect a bit of movement - it will add to the experience I think. So I would 'consider' how much it moves under wind, and decide if that is OK or not. I would not worry about vibration for the crows nest.
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