Wiki Page: 08. Why does adding a node point change the soil settlement displacement in AutoPIPE?

Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Modeling Subarea: Original Author: Bentley Technical Support Group Item #8, Question: Why does adding a node point on segment with soil settlement (impose displacement) already defined make a big difference in the results. See following image and results At node A02 & B02. Note: Soil settlement (impose support displacement) was only modeled for the center elements on both segments: Segment A and B were identical, then node points A04 and A05 were added. Now the results are very different. Why? Answer: The way AutoPIPE stores soil information and how imposed support displacements are applied to soil points explains the issue mentioned above. Looking at the updated model below: AutoPIPE stores the soil information for an element with the preceding node i.e. soil information for the segment B, element B02 - B03 is stored at node B02. When the intermediate point A05 is inserted between A02 and A03, the impact of imposed support displacement applied at A02 is limited to intermediate soil points up to A05. Whereas in segment B, the impact of imposed support displacement applied at B02 continues up to point B05. Fix, need to apply another imposed support displacement at point A04 and A05 that corresponds with the same displacement found in segment B at the same location. Example: Assuming soil point B02 +3 is the corresponds with A05 on Segment A, Select A05 and add an impose support displacement = -0.262" If we apply this resulting displacement value at the newly inserted point A05, we would have slightly better matching results: The applied displacement value was a result value, and not really the actual imposed displacement, however we can see that we get a much better result now See Also Bentley AutoPIPE External Links Bentley Technical Support KnowledgeBase Bentley LEARN Server Comments or Corrections? Bentley's Technical Support Group requests that you please submit any comments you have on this Wiki article to the "Comments" area below. THANK YOU!