| Applies To | |||
| Product(s): | AutoPIPE | ||
| Version(s): | 2004, XM, V8i, CONNECT; | ||
| Area: | Modeling | ||
| Original Author: | Bentley Technical Support Group | ||
| Date Logged & Current Version | June. 2016 10.01.00.09 |
Problem:
How to model a Trapeze / Beam supported pipe in AutoPIPE?
Solution:
This is very simple and easy to do.
First, see the following AutoPIPE help section:
Help > Contents> Contents Tab> Modeling Approaches> Modeling Approaches> Frames> method 1, 2, & 3.
This will enable you to create the pipe, bottom beam, and insert the support between the pipe and bottom beam.
Note, the model must contain Beam node points where each spring is connected and where each pipe support is connected.
Next, insert the beam located above the pipe, the top beam node points should be directly above the bottom beam node points so that the inserted spring can is exactly vertical when connected . Now, Insert a set of anchor on each end of the top beam. This signifies that the top beam is held rigidly in place. Finally insert springs from the bottom beam connected to the top beam.
Example:
1. Open model with Piping
2. Insert bottom Beam
Note: Remember the bottom beam must contain beam node points to connect 1 pipe support and 2 spring cans. Suggest using 2 short beams connected together.
3. Insert Pipe Support to bottom beam (ex: from B01 connected to beam node point M004)
4. Insert Top Beam (ex: M001 to M002)
5. Insert Spring support between corresponding top and bottom beam node points (ex. M001 - M003), repeat this step to add a 2nd spring support.
Note: User must enter the cold load or set to Undesigned and perform a Hanger Analysis.
6. Insert Rigid Anchors on both ends of top beam (ex: M001 & M002)
Note: the top beam does not need to be modeled because it is presumed to be a rigid mounting point. Therefore one could model the spring supports connected to ground and the results would not change.
However, if the weight and flexing of a overhead beam needs to be considered than model the over head beam back to a place that could be considered and anchor point (ex. large vertical column).
7. Each component or series of components need to be supported / anchored in such a way as to not cause the following warning when running an analysis E801-1: FATAL ERROR : Unstable system. Typically this is accomplished by adding an anchor to each disconnected system of components. In this model approach, this error message will appear if the bottom beam is left as is. The fix here is to add an extremely flexible anchor anywhere on the bottom beam.
Example: Add an flexible anchor to node point M005 (pictured above), Set Anchor type to Flexible, use very low stiffness values: 0.01 lb/in, & 0.01 ft-lbs / deg as needed.
8. Done...
Conclusion:
This modeling approach takes into consideration weight of the piping system and weight of the supporting beams. This approach is easily expandable to accommodate more pipes on the same beam held aloft by only 2 supports. this is done by adding more lengths of beams and additional connections points for more pipe supports. See example of 2 pipes on the same support below: