Applies To Product(s): AutoPIPE Version(s): ALL; Area: Modeling Date Logged & Current Version March 2020 12.02.00.14 Problem: Pipe is installed in a trench sitting on compacted ground (operating condition #1). While the trench is open the pipeline is then put into service. Therefore the pipe would be free to move in Trans Vertical Up, Trans Horizontal, and Logitudnial directions to a new "hot" configuration (operating condition #2). While the pipe is in the new HOT displaced state (operating condition #2), the trench is then back filled and compacted per project documentation. Afterwards, the pipe is allowed to cool of returning to original installed state (operating condition #1). How to model this scenario? Solution: Let us consider the fundamentals of a Non-Linear Analysis. AutoPIPE applies operating conditions as directed by the "Base load cases for nonlinear analysis" setting mentioned in Analysis Summary sub-report . Each load is applied one at a time to the model in its current initial displaced configuration, the program calculates the displacement, forces, moments, stresses, etc.. based on degrees of freedom to move to a new initial displaced position. Then the next load case in the sequence is then applied to the new initial displaced position again performing said calculations. Once the analysis has been completed, results are calculated based on combination settings. As of March 2020, AutoPIPE cannot apply a new support or soil properties starting at a specific load case. Therefore, suggest the following modeling approach. Summary: Calculate the Hot configuration displacement (operating condition#2) and make it the starting point for analysis back to original operating condition #1. 1. Model the original piping configuration (operating condition #1). 2. Insert soil properties to represent piping resting on bottom of trench. 3. Analyze system. 4. Open Point tab on the input grids, copy the entire grid to Excel. Call this the initial installed location (see global coordinates). 5. Open Results Grids, display operating condition only, and copy grid information to Excel Remove all lines that do not correspond with input grids (ex. intermediate soil points. A00 +1, A00+2, A02N+1, ect...) Note : AutoPIPE does not report displacement of an Elbow TIP point, therefore decide if elbow displacement is based on Near or Far point. Then remove all non-corresponding lines. In this example, Near point was used as elbow TIP displacement. 6. Using Excel, calculate new global coordinate based on original location and applied operating condition (add displacements to original global coordinate). 7. Save original model. Then use File> Save As> AutoPIPE model (*.DAT), save to a new name. 8. Highlight new calculated global coordinates in Excel, and copy back into AutoPIPE's point tab grid 8. Reconfigure Ambient temperature to that of operating temp above 9. Update Operating conditions as needed 10. Insert Soil properties to represent a trench with backfill 11. Run analysis. See Also Modeling approches Bentley AutoPIPE
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