IH1980
Structural
- Nov 20, 2014
- 27
Hi all. I have a problem I need some advice on.
I am designing a thing for a client where they are installing a truck on top of a totem pole outside their truck factory, as a feature at the entrance. So this thing will be a 6000Kg truck tilted at 30 degrees (as if driving down a hill) on top of a single post, about 4m to the lowest point ie front bumper. In the static case the centre of gravity is about concentric with the post. For wind I have worked out the area and treated it as a vertical cantilever from a pad foundation (4m x 4m x 0.8m) using a 400 x 400 SHS post. This gives around 90mm deflection at the top under full wind loads.
I am a bit concerned about it maybe become dynamic under wind loads (no seismic concerns here in the UK). I can't find a lot of info but in the Eurocode for lattice masts and towers, it says that anything with a fundamental frequency of greater than 2hz does not need to have its response checked (BS EN 1993-3-1 2006 B.4.4 (5). I have used the Blevins formula for a single mass on the end of a cantilever and get 1.8hz.
Two questions: 1, is my method appropriate, and 2, am I being unnecessarily concerned here?
All comments welcome!
Ian.
I am designing a thing for a client where they are installing a truck on top of a totem pole outside their truck factory, as a feature at the entrance. So this thing will be a 6000Kg truck tilted at 30 degrees (as if driving down a hill) on top of a single post, about 4m to the lowest point ie front bumper. In the static case the centre of gravity is about concentric with the post. For wind I have worked out the area and treated it as a vertical cantilever from a pad foundation (4m x 4m x 0.8m) using a 400 x 400 SHS post. This gives around 90mm deflection at the top under full wind loads.
I am a bit concerned about it maybe become dynamic under wind loads (no seismic concerns here in the UK). I can't find a lot of info but in the Eurocode for lattice masts and towers, it says that anything with a fundamental frequency of greater than 2hz does not need to have its response checked (BS EN 1993-3-1 2006 B.4.4 (5). I have used the Blevins formula for a single mass on the end of a cantilever and get 1.8hz.
Two questions: 1, is my method appropriate, and 2, am I being unnecessarily concerned here?
All comments welcome!
Ian.