Wind Load Application- Incorrect?

Question

Hello, 
 
 I applied a wind definition and 2 related load case details for wind (wind in the +X and +Z directions) on the structural members in my model. When I run the analysis and look at the post processing results, there are zero moments or reactions for the wind load cases, which I know is incorrect. The structure that I am analyzing is plated 360 degrees around the circumference of the vessel. When I run the wind load cases with consideration to an 'open structure' I get the correct reaction forces that I am expecting from the analysis. Why is this? I do not have an open structure, so this seems to be incorrect to me? 
 I have attached the model with consideration to an 'open structure'. Please elaborate! 
 
 Thank you in advance, MTO_SDA_RevB.std 
 Erika

Sye · Answer

For wind loading on closed structures, the software needs to have closed panels made of beam elements on all sides or beam elements on all sides except one which may be defined as supports. In your case such panels are not formed. Also you may know that STAAD.Pro can do automatic wind load generation on beam elements only and not on plates. 
 To get the wind load to work for your structure, you may have to create dummy beam elements connecting all the nodes for the plate mesh. A material with zero density and negligible E may be assigned to these dummy members. Else you may apply the wind loading directly as plate pressure load instead of using the automatic wind load generation. 
 The following wiki has more details on the topic 
 
 It is not correct to use open structure for your case as that would only consider the surface area of the beams, that is obstructing the wind, to generate the wind loading.