How To: Define an Eccentric Antenna Load on a Pole in RISA-3D?

Using RISA-3D's  various modeling and loading tools, makes modeling telecom structures easy and efficient. RISA-3D allows engineers to quickly explore numerous design variations before physical implementation.

When modeling the equipment dead load as a point load, have the point load applied at the center of mass of the equipment. However when the center of mass is not aligned with the pipe's, you can use one of two methods below:

• Use rigid links to transfer the eccentric load

• Apply a point moment load at the equipment support point due to eccentricity

METHOD 1: Using Rigid Links

If the pole centerline is different from the mount centerline and you want to capture this in the model, you will want to use rigid links. Follow the steps below:

1. Model in your structural pipe member

2. Then draw small rigid links that extend perpendicular from the pipe

3. Then place your loading at these rigid link locations so that the offset is captured. See an example of this below.

   

    

By default the program already has a rigid member set up for you within the section sets > general material. To use this member you can use the following settings when drawing your rigid links.

Link: Rigid Links in RISA-3D

METHOD 2: Applying Moment Point Loads

If the pole centerline is different from the mount centerline and you want to capture this in the model, you can also apply moment loads directly at nodes. Calculate the moment load (M) by W x Rigid Link length (distance). Then follow the modeling steps below:

1. Model in your structural pipe member

2. Add nodes along the pipe member where the antenna attachment loads will occur. You can use the Node Coordinates spreadsheet or Add Nodes under the Modify tab.

   

3. Place moment point loads using Point Loads or Nodal Loads under the Home tab.

   

   
   

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