How are wind loads automatically generated?
Question:How are wind loads automatically generated?
For this example we will use a structure similar to the one shown in the figure. On this structure we will generate the wind loads according to Eurocode EC1, General load.
The first step is to be sure that the wind loads will be generated according to the desired norms. Verify the "Configuration" window from the "File" menu.
To be able to automatically generate the wind forces, windwalls must be defined. The windwalls are special elements, without self weight, with the single purpose of taking and sending the loads to the structural elements.
The windwalls, next to the plane that makes the connection with the ground, must form a closed volume with the same shape as the structure.
The creation of the force family is not different from other load families, and is done by using the "New" command from the "Modeling toolbar:
This command will open a window from which a load family is selected: Wind EN 1991-1-4. The name of this family is created according to the standards; this is a way to verify the norms used by Advance Design.
A load family named: "Wind EN 1991-1-4" will be created in the "Pilot".
Select the wind load family and its parameters from the properties window. Insert the wind speed (45m/s), the wind direction (the positive X axes direction), the building height (4m) and the terrain category (category III terrain).
It is easy to see that, depending of the values inserted for the dynamic base parameters, the values of the dynamic effect are actualized in real time.
After the wind load family parameters are defined, the wind loads can be automatically generated. Select the load family from the "Pilot and by right clicking on it, select the "Automatic Generation command.
In the "Pilot", in the wind load family, two load groups are created: "VX+S" and "VX+D". Each group corresponds to the calculation with one of the two values of the internal pressure coefficient Cpi. The internal pressure coefficient Cpi is taken into account with two distinct values: -0.2 and +0.3.
In the CAD area we can see the forces from the two groups, represented on the structure. For a better understanding of these forces we will systematically select and hide some of them from the "Pilot".
First we will hide the "VX+D" group entirely and make visible only "VX+S". These values correspond to a calculation with a value of Cpi=+0.2:
The following figures are for "VX+D". The values correspond to a calculation with a value of Cpi=-0.3: