topic Re: Wind Loads simulation. Help needed. in Robot Structural Analysis Forum

Wind Loads simulation. Help needed.

skilak — Thu, 09 Oct 2014 12:35:32 GMT

Hi,

I am trying to use the Wind Load Simulation but I have a concern, namely, I would like to know what kind of wind speed I shall use. The standards and met offices use mean values e.g. 3sec gust, 10minute mean (EC) or 1hour mean (BS5950). I am working on a project where I am using 3sec gust and comparing it to the WLS the second option gives sometimes twice bigger results. I could imagine that if I am using an object bigger than a 5in pipe then I would tend to use a sustained type of wind (10min). Please advise.

Best regards,

Re: Wind Loads simulation. Help needed.

Rafal.Gaweda — Thu, 09 Oct 2014 12:37:41 GMT

Check this thread:
http://forums.autodesk.com/t5/robot-structural-analysis/terrain-type-wind-simulation/td-p/5238985

Re: Wind Loads simulation. Help needed.

skilak — Thu, 09 Oct 2014 12:52:30 GMT

I saw it, no use:( In the whit paper it was written that longer simulation would give better results as more data was collected - smaller values. My concern is taht if you have a sample of wind e.g. 3sec - peak pressure then it cannot happen simultaneously on both opposite sides of a building at the peak value - this is why you have to use a sustained wind e.g. 10minutes mean ................... other words, can I assume: if I hold the simulation for 3sec it gives me equivalent of 3sec gust wind type?

Re: Wind Loads simulation. Help needed.

skilak — Thu, 09 Oct 2014 14:16:05 GMT

Update,

OK, I have some results. A box above a ground 3.347x5.081x4.253, first fiugre is normal to X in Robot. I have done three wind loading models A) EC1 B) 67m/s software default C) 67m/s but I hold it the simulation to reach 3sec duration of simulation.

So. the results

A) Including non-simultaneous action reduction factor of 0.85 the overall force is 2.946 kPa

B) Overall force is 3.366 kPa

C) Overall force is 2.964 kPa

My observations: Short duration of the simulation gives peak values almost everywhere (on every face of the object). Wind simulation in Y direction is kind of bollocks (as I have seen already been reported).

Attached are the screenshots of the system, the mentioned above box is on the top.

Re: Wind Loads simulation. Help needed.

skilak — Fri, 17 Oct 2014 13:16:04 GMT

Hi,

I have read again the Autodesk Robot Structural Analysis Professional wind simulator validation brief and it refers to 1hour mean wind speed for wind tunnel test and states the RSA simulation was based as well on 1h mean wind. Shall I assume that RSA uses 1h mean wind speed? and perhaps if I have to use e.g. 3 sec gust then I have to convert it to 1h mean? e.g. 1.05Vref1h= Vref10min= 0.84Vref1min= 0.67Vref3sec ??

I think a guide would be required in this field.

Cheers