Wind Load Warning

Question

Hello Staad Experts , 
 During Wind Load generation, i often come up with the following warning 
 :WARNING-fx fy fz wind forces: 0.0000E+00 0.0000E+00 -1.6585E-01 at coordinates: 7.4975E+00 8.6465E+00 0.0000E+00 ignored. 
 Why is this coming up?

Shany · Accepted Answer

There are few instances where the WIND load command is not associated with a specific exposed face. So, the program has to scan through the whole structure to find one. When it runs into what it perceives as intersecting members without a common node at the intersection point, these messages are displayed. 
 I would suggest you to provide the coordinates of the Exposed area with some tolerance as X range ,Y range and Z range in the wind load case definition ,so that the concerned nodes are covered by the ranges . This helps the program to identify the proper exposed area for wind load. Or you can associate them with a member list or a group name in each case, and the message will disappear.

Modestas · Answer

Select member 85, right click on the screen and go to Insert Node. Now enter 0.8m in the Distance field and click Add New Point button. Click OK and Yes. Now reanalyze the model and those warnings should not exist anymore.

DSANJU · Answer

Could you please upload the model?

DSANJU · Answer

Please refer to the attached modified model where you can see Wind Loads are applied on proper beam group (Group name :_B1). The beam group is created with the members where the wind loading in X direction is supposed to be generated. 
 
 0844.Sriteja S+G+4.std

DSANJU · Answer

With your normal Wind loadings with ranges, the program is scanning the structure and trying to locate the portion where the loading will be generated. It is wrongly identifying the highlighted portion and failing to generate the loading over there. On using predefined beam group for wind load generation, the problem can be easily solved.

DSANJU · Answer

There is no problem in geometrical modelling of the structure. It is due to the problem of the wind loading only.

DSANJU · Answer

Glad to hear that.

Sye · Answer

For the wind load generation to work on all areas, you need to ensure that members in these areas form closed panels. Closed panels are formed when beams/columns enclose an area from all four sides. Alternately the area may be enclosed by beams/columns on 3 sides and support on the other side. You model has many areas where such closed panels are not being formed. If you want to use the automatic wind load generation, you may have to add dummy beam/columns to form these closed panels. Use a different material with small E and zero density for these dummy members. 
 
In addition if you are using PDELTA analysis you should replace your LOAD COMBINATIONS by REPEAT LOADs. The following wiki explains how to convert the Load combinations to REPEAT LOADs 
 
 communities.bentley.com/.../30456.how-to-convert-a-load-combination-to-a-repeat-load