Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: report Subarea: Original Author: Bentley Technical Support Group Comments, Questions, and Answers for Support sub-report using Results Output Report in AutoPIPE Item #1, Question What is the difference between the support and the restraint output reports? There seems to be some overlap. Answer: For last 21 years AutoPIPE has had a Support and Restraint output report (yes there is some overlap), The Restraint report is the piping loads on supports and Anchors shown in Global axis system where as the Support forces report shows only piping loads on Supports but includes both local and global force/moments and displacements. Note, there is only support report on the StressISO which finds maximum loads from whichever non-code combination(s) is selected. Item #2, Question Why are membrane stresses from pipe supports not included in AutoPIPE? Background In addition to the general large scale pipe stresses calculated in AutoPIPE. there are local pipe membrane stresses produced by pipe supports acting on the pipe wall. The transfer of load from the pipe support surface to the pipe wall over a given contact area may produce substantial membrane stresses. Another example is restraint of the thermal and internal pressure radial expansion. A pipe expanding within a full encirclement clamp support may again lead to substantial membrane stresses. Membrane stresses are a largely influenced by support type, support stiffness, and contact area. There is general lack of knowledge about membrane stresses that occur at supports within the pipe stress industry. Answer: In plane and out of plane membrane stresses may occur at a pipe support due to normal bearing action or due to friction between the pipe and support. A centerline model created using beam bending elements is not able to capture these effects. Hence, membrane stresses are not included in AutoPIPE centerline models. The effects of these membrane stresses may not be significant in small bore pipelines (D/t 100) which is the normal range of application of majority of piping codes. For large bore pipelines (D/t 100), these stresses can be significant and may lead to an un-conservative estimation of total stresses if they are not considered using FEA or Roark's formula. Hence, it is important to account for these stresses using special methods like FEA or Roark's formula. We plan to address this in future release of AutoPIPE by including ability to model local membrane effects using shell elements. User defined stress concentration factors may be used to model these effects in AutoPIPE which could give a close approximation to refined FEA analysis. We appreciate your suggestion and will consider adding a note or warning in our product documentation. By user defined stress concentration factors we meant Insert/Extra Data/ Joint Type and user SIF. This issue has been logged as a new enhancement, TFS-72841: Include an ability to model local membrane effects using shell elements for pipe supports, to be added to a future version of the application. Item #3, Question When reviewing the results of a guide support with gap in the horizontal (global X-dir) and vertical (global Z-dir) set to 0.00 inches during a non-linear analysis, noticed that the support was moving with the pipe. Deflected shape for T1 load case: How can this be happening? How to fix it? Answer: When reviewing Tools Model Input listing, Extended Component sub report, the following was found in multiple PipeID's in the model : "NaN" Note: Something has happen to this model and the results should not be trusted while "NAN" can be found in a complete output report with all applicable sub-reports checked ON or while searching a complete model input listing report. If you encounter this issue, please try to write down exactly how this was accomplished or provide as much model history as possible (created in what version, how was the model created, import , copy clip, what cands were in use, etc..) then create a Bentley Service Request , and send the details with your model APC file (File model management Save Archive *.APC) for review. Avoidance: there are 2 solutions to fixing this issue: Option #1: a. Open the model in AutoPIPE b. Select the Pipe Property Tab from the Input grid c. Scroll to the the right on this tab until the " Pipe material " column can be seen. d. Change the material from the original setting to another selected material in the library for each PipeID in the model e. Change the pipe material back to the original setting for each PipeID in the model. f. Perform an analysis, search both a complete output and model listing report for NAN. Option #2: a. Open the model in AutoPIPE b. Select the Pipe Property Tab from the Input grid c. Scroll to the the right on this tab until the "Cladding Density" column can be seen. d. Change the density value from the original setting to another value for each PipeID in the model e. Change the density value back to the original setting for each PipeID in the model. f. Perform an analysis, search both a complete output and model listing report for NAN. After performing the above avoidance, both the results and deflected shape are corrected.: The CAE development team is reviewing the program in hopes of preventing this in future versions of the program (AutoPIPE V8i 09.06.01.xx and higher). 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!
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