Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Modeling Subarea: Original Author: Bentley Technical Support Group Attention: Please see the following AutoPIPE help sections: Help Contents Contents Tab 1. Reference Information Pipe Soil This section will provide information on a. Model Discretization b. Defining Soil Points in AutoPIPE c. Soil Restraint Properties in AutoPIPE d. Calculation of Soil Restraint Properties - AutoPIPE Method e. Calculation of Soil Restraint Properties - ASCE Method f. Comparison of Soil Restraint Properties g. Soil overburden stresses application on AutoPIPE points 2. Modeling Approaches Example systems PIPE-SOIL Interaction: Transition Example. The purpose of the following example system is to demonstrate the procedure required to a. Calculate soil properties using AutoPIPE and ASCE method b. Verification of values with hand calculations c. Determine the location of critical piping points to be defined for the above to below ground (transition) piping system shown in the Figure below. In this example, the piping system is subjected to a temperature rise of 230°F, and an internal pressure of 100 psi. For simplicity, a single soil will be assumed to interface with the pipe over the entire length of the buried portion of the system. This online help section will provide step by step procedure of modeling soil properties in AutoPIPE. Comments, Quesions, and Answers about Soil Properties: Item #1: What will be the yield displacement value for following - yield displacement to calculate longitudinal loose clay soil spring stiffness; - yield displacement to calculate longitudinal loose sandy soil spring stiffness; Answer: Per the onlne help for this parameter, Longitudinal Yield Displacement, y1L [inch] Enter the longitudinal yield displacement. The value is used when calculating the soil resistance, p1, in the longitudinal direction. Defaults: Low = D/60, High = D/25. Also, per the AutoPIPE soil example (mentioned above): For medium sand, assume the value of yield displacement to be d/45. Bentley is not able to provide a specific values for modeling, must use engineering judgement or consult a soil engineer when determing values such as this. In addtion, AutoPIPE's Soil calculator can consider high, low, and avg values when generating soil spring stiffenss values based on soil parameters. Item #2: Would it be appropriate to design fault line crossings by applying an offset to the pipeline? Are there any other way to model this? Answer: AutoPIPE provides the ability to the user to be able to generate soil stiffness properties using the method provided in ALA guideline (ASCE 2001: Guidelines for the Design of Buried Steel Pipe). Using the imposed support displacement with a buried pipe model, it may be possible to model a fault line crossing. There is no specific workflow currently in AutoPIPE to model a fault line crossing. You can model a buried pipeline by provide the soil stiffness values in four directions, and then apply imposed support displacement values (e.g. If your total fault line displacement is say 10", you may start by providing 1" imposed support displacement from one piping node, increment that until you reach 10" total displacement). You may continue the imposed displacement after the fault line crossing keeping it at 10" until a virtual anchor is reached. The displaced model would look something like the one shown below: 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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