Applies To Product(s): AutoPIPE Version(s): 2004, XM, V8i Environment: N/A Area: Subarea: Original Author: Bentley Technical Support Group Date Logged & Current Version Mar. 2015 09.06.01.10 Problem: All things being equal in the model except for wind speed. Found that pipe code stresses from W1 speed = 100 mph are higher than stresses from W2 speed = 110 mph. It appears that the wind pressure is correct from the model listing file. Is there a problem with AutoPIPE calculations? Answer: AutoPIPE is working correctly. Caution when reviewing the Model Input listing "Load Summary" sub report for Wind 1 and Wind 2, see the foot note highlighted below: For more details, please see the following explanation: This is a boundary value problem, in which AutoPIPE will jump from using an automatic Cf (force coefficient) value of 1.2 down to 0.7. AutoPIPE only takes in to consideration diameter D and qz value when calculating automatic Cf. When D*SQRT(qz) > 2.5, AutoPIPE uses a value of 0.7, otherwise AutoPIPE will use a value of 1.2. This may result in decrease in wind forces around that boundary condition. Please see the following AutoPIPE help section for complete details on this subject: Help > Contents> Search Tab> enter "Force coefficient Cf (ASCE 7-02)" (include the quotes), press List Topics button, double click on the selected topic from the list provided to see more information. Workaround : Only perform this step if you do not accept using the CF = Automatic explanation above. Instead of using Cf = Automatic, enter a user defined value (ex. 0.7) to be used for all piping regardless of height and pipe diameter. 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! TFS-D187758.
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