Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: Modeling Area: Subarea: Original Author: Bentley Technical Support Group Logged: Nov. 2014, AutoPIPE V8i 09.06.01.10 Problem: I would like to request advice on a modeling approach. We want to use FRP piping for a large (DN900) buried irrigation scheme. The FRP system is prefabricated pipes lengths that are joined with sliding couplings. These couplings offer no axial restraint for the pipe therefore at the bends there is a pressure thrust force that must be resisted to stop the pipes sliding from the couplings. This is not uncommon and usually would be solved by installing a concrete thrust block, however, this application is remote and the quantity of bends are high. We would like to use a straight length of pipe either side of the bend and utilize friction and bearing from the pipe/soil interface to overcome the thrust force instead. I could calculate the straight length of pipe required to provide enough friction and bearing to ensure the pip e remains in place within the coupling and is not over stressed. However, I would like to use AutoPIPE to carry out this calculation as it: - Can easily solve the complex non-linear interaction of the pipe and soil to resolve bearing forces - Has ISO 146 92 for calculation the FRP stress values We are currently struggling with how to approach the modeling for this situation. Primarily how to define the boundary conditions of the model since the piping is sliding in the couplings and therefore there is no fixed point. The couplings can tolerate a certain amount of axial pipe movement before the pipe slides out and fluid is released. Therefore we would like to be able to iterate my model by increasing pipe length until the movement below the maximum amount of axial movement required at the coupling is detemined. Q1. Can AutoPIPE be used to model this scenario or does the lack on a fixed point on the model make it impossible? - Q2. If it is possible, how should the conditions at the coupling ends of the piping be modeled? Q3. Is there any other advise that would help with the accuracy of my model? Answer: AutoPIPE does not support this type of optimization where a maximum displacement is a boundary condition for determining the length of a run. The lengths of the pipe are the initial conditions to which the displacement and stresses are calculated. This would have to be a trial-and-error on the user end. The user would have to create a series of lengths and review the resultant displacement at the piping end node points where displacement is desired to be = 0.00. In addition, one of the components of resistance in the axial direction can be approximated from virtual anchor length calculations i.e. length at which there will be minimal pipe strains. However, as the calculations are required near a bend point, so the lateral bearing forces will also provide reaction to the pipe. It is advise the user to go through following AutoPIPE online information: Please see the following AutoPIPE help section: Help > Contents> Contents Tab> Modeling Approaches> Example Systems> PIPE-SOIL Interaction: Transition Example (particularly the "Determination of Zone Locations" document) and Help > Contents> Contents Tab> Reference Information> PipeSOIL> (particularly the "Model Discretization" document) Knowing the virtual anchor length may help the model converge quickly. Another thing, to better model soil by keeping the maximum soil spacing small in the length Lb (calculated from AutoPIPE virtual anchor length dialog) near the bend. This will increase accuracy of the calculated forces and displacements. Apart from these two things, again to suggestion modeling a couple of length of pipe from the sliding coupling in each direction from the bend and through trial and error determine> the pipe length needed for zero node point movement.. 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! Please see the following AutoPIPE help section: Help > Contents> Contents Tab> Reference Information> Code Compliance Calculations>
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Wiki Page: 10. Using AutoPIPE to determine pipe length needed for underground design
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Wiki Page: 01. What will be the yield displacement value for following in AutoPIPE?
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Modeling Subarea: Original Author: Bentley Technical Support Group Dec 2014, AutoPIPE V8i 09.06.01.10 Problem: 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 online 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 determine values such as this. In addition, AutoPIPE's Soil calculator can consider high, low, and avg values when generating soil spring stiffness values based on soil parameters. 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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Wiki Page: 02. Would it be appropriate to design fault line crossings by applying an offset to the pipeline being modeled in AutoPIPE
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Modeling Subarea: Original Author: Bentley Technical Support Group Dec 2014, AutoPIPE V8i 09.06.01.10 Problem: 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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Wiki Page: 03. Cannot validate AutoPIPEs results, specifically for the Qu term (vertical up) for sand, what is causing the difference?
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Modeling Subarea: Original Author: Bentley Technical Support Group Dec 2014, AutoPIPE V8i 09.06.01.10 Problem: I have been doing a hand calc verification of the American lifeline s alliance (ALA) soil calculator, and cannot validate AutoPIPEs results, specifically for the Qu term (vertical up) for sand. The equations should be Qu = Nqv * Density * H * D, where Nqv = (phi * H) / (44 * D) I ran a coarse parameter study with many cases, and got proportionality for phi and density (which is good) and weirdly proportional to H/D. With my second parameter study, just looking at H/D, it looks like there is an additive term that I can't identify. what is causing the difference? Answer: There are 2 calculation differences identified from your had calculation in AutoPIPE. 1. Value of Nqv should be taken as less than Nq value: 2. Please note that gamma*H*D is meant to calculate the weight of soil on top of pipe. AutoPIPE calculates the weight of soil on top of pipe + considering the weight effects on sides of pipe as well. Thereby calculating weight of soil more accurately than found in the code: AutoPIPE calculates Qu as Note: cohesion of soil c = 0. 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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Wiki Page: 04. How to model a 420 km long buried pipe, including traffic loads and large radius bends in order for the pipe to travel under a river in AutoPIPE?
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Modeling Subarea: Original Author: Bentley Technical Support Group Dec 2014, AutoPIPE V8i 09.06.01.10 Problem: How to model a 420 km long buried pipe, including traffic loads and large radius bends in order for the pipe to travel under a river in AutoPIPE? Any recommendations? Answer: Bentley Technical support does not have any example models of a pipeline as described above. However the online help and example documents cover all these topics in detail. It would be just a matter of applying typical AutoPIPE commands and information from various documents, online help, or WIKIs to the situation. For the pipeline example above: a. Route the pipe as needed using typical AutoPIPE commands b. Model a large radius bend with the Ring Command or as 1 large bend c. The soil tutorial PDF's (available in AutoPIPE V8i 09.06.xx.xx and higher, folder location = C:\ Bentley\ AutoPIPE V8i SELECTseries\ Documents) installed with program are a good starting point to understanding soil in AutoPIPE. Also see the PipeSoil Example in the AutoPIPE's online help> Modeling Approaches. d. Apply soil properties as needed along the pipe e. Apply traffic loads as needed with the Edit Soil properties> Soil Overburden Loads command (refer to the "Tutorial - Soil Overburden and Seismic Wave Propagation in AutoPIPE.pdf" in the folder location mentioned above). 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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Wiki Page: 05. In the Virtual Anchor Length equation (La = Co * Lm), how can the value for Co be adjusted in AutoPIPE?
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Modeling Subarea: Original Author: Bentley Technical Support Group Dec 2014, AutoPIPE V8i 09.06.01.10 Problem: In the Virtual Anchor Length equation (La = Co * Lm), how can the value for Co be adjusted? Answer: From the online help: Co = Dimensionless constant which lies in the range from 1.0 ("stiff" soils) to about 2 (soft soils). The magnitude of "Co" can be greater than 2.0 if the longitudinal yield strength (P1 ) is not achieved by the soil.Comparison of analysis results for similar system models with various virtual anchor lengths indicate that estimated values of "Co" should be limited to the following range (unless a larger value can be justified): 1.5 </= Co </= 2.0 The system model can be terminated and anchored at a distance away from a bend (or tee) equal to the virtual anchor length (La) without any loss of accuracy to the analyzed results. Depending on the overall configuration of the piping system and the type of analysis to be performed, the inclusion of Zone 3 in the system model may or may not be necessary or desirable. This decision is left to the judgement of the Engineer/modeler. In conclusion, AutoPIPE does not currently (v.09.06.xx.xx and lower) allow the value of "Co" to be adjusted by the user. It is set at a constant value of Co = 2.0. With regards to modeling, having an adjustable value of "Co", the virtual anchor length "La" value will only be shorten by a small order of magnitude. 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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Wiki Page: 06. How to model horizontal buried piping going under roadways / railways?
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Modeling Subarea: Original Author: Bentley Technical Support Group Dec 2014, AutoPIPE V8i 09.06.01.10 Problem: How to model horizontal buried piping going under roadways / railways? Answer: Any piping under a Roadway or Railroad are highly regulated by the respective municipalities (i.e. DOT, CSX Railroad, etc..). These companies will have clear guidelines about any pipeline crossing depending on the depth of cover. Recommend that you refer to these type of design specifications as needed for your design. Pipeline buried with no casing - Simply model the pipe routing and apply soil properties as needed. Refer to the "PIPE-SOIL Interaction: Transition Example" in the AutoPIPE's online help for techniques of apply vertical soil and horizontal soil properties. Pipeline buried with casing - Typically a carrier pipe will be properly encased within a steel casing of length as determined by the design documentation. See the following procedure: 1. Model the carrier pipe routing as needed. Be sure to add node points on the carrier pipe where spider supports (supports that centers the carrier pipe inside of the casing) are placed inside of the casing over the length of the casing. 2. Insert the casing pipe by selecting the same section of the carrier pipe that matches the casing length, copy, and pasting this section in the exact same location with a slight offset (ex. Dy = 0.1") as a new segment. Finally apply the correct PipeID with casing pipe properties to the new segment. 3. Select the node point on the carrier pipe where the spider supports are to be placed, insert a support (V-stop, Guide, incline), specify the corresponding casing pipe node point for the support's "Connected To:" field. Thus supporting the carrier pipe from the casing pipe. 4. Model the end connections of the casing to the carrier pipe Rubber boot / Seal-Wrap - not really considered a support, nor does it provide any form of resistance to pipe movement. AutoPIPE modeling approach would be no component at this location. Casing welded to Carrier pipe - select the casing end point insert a rigid beam to the corresponding carrier pipe node point. Length of rigid beam will be the same as the offset from Step #2 above (ex dy = 0.1"). Pipe Seal / Link Seal - rigid rubber links that are tighten to provide a leak proof seal. AutoPIPE modeling approach, insert another support (i.e. Guide) similar to a spider support with 0.00" gaps in all directions and a higher friction force. Traffic Load: AutoPIPE V8i 09.06.xx.xx and higher has the ability to calculate soil overburden stresses for a horizontal buried pipe line crossing a roadway / railway track taking in to account the live load from the traffic. 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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Wiki Page: 07. How to model vertical Air Shafts - large diameter vertical underground piping in AutoPIPE?
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Modeling Subarea: Original Author: Bentley Technical Support Group Dec 2014, AutoPIPE V8i 09.06.01.10 Problem: How to model vertical Air Shafts - large diameter vertical underground piping up to a half mile long, going straight down with external ring braces every 10 to 15 feet ? Answer: Consider the following modeling approach: 1. Model vertical piping with the correct pipe properties as needed.. Confirm code requirements for D/t are not exceeded (typically D/t = 100). 2. Apply soil properties as needed to the vertical piping (may needed more than 1 soil property). 3. Account for the ring braces with different pipe properties. Note: AutoPIPE performs analysis based on piping code requirements. Some parameters (Pipe OD to wall thickness ratio) in this modeling maybe outside of the selected piping code limitation and may provide an incorrect analysis. Be aware of the selected piping code and program limitation for this type of modeling. 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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Wiki Page: 11. Do we have to define the soil properties after the La (i.e., in Zone 3)?
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Modeling Subarea: Original Author: Bentley Technical Support Group Dec 2014, AutoPIPE V8i 09.06.01.10 Problem: Do we have to define the soil properties after the La (i.e., in Zone 3)? If yes, what will be the max soil spacing after the virtual anchor length (i.e., in zone 3)? Answer: Please see the following AutoPIPE help section: Help > Contents> Contents Tab> Reference Information> PipeSOIL> Model Discretization> Figure D-1: Comparison of a buried pipeline with a bend to an infinite beam on a continuous elastic foundation. All piping in AutoPIPE is supported by Pipe supports or Soil points, otherwise the pipe is free spanning. Theoretically, an anchor node point can be modeled anywhere in Zone 3 and no additional piping will need to be modeled. Another words, as mentioned in the online help, piping system can be terminated and anchor at La distance from the elbow (i.e. Zone 3). However, the user can choose to model the entire piping system past the La dimension by adding additional node points and soil points along the pipe as required. What soil spacing should be used in zone 3? As an estimate, suggest using the same soil spacing as mentioned for Zone 2, try increasing this spacing while reviewing the results to see if they are affected. The final maximum soil spacing in zone 3 becomes an engineering judgement. 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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Wiki Page: Model Soil Properties with Soil Calculator and Underground Piping in AutoPIPE
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, Questions, and Answers about Soil Properties, Soil Calculator, and Underground Piping: Item #1: What will be the yield displacement value for following 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? Item #3: Cannot validate AutoPIPEs results, specifically for the Qu term (vertical up) for sand, what is causing the difference? Item #4: How to model a long undeerground pipeline with traffic loading and large radius bend? Item #5: In the Virtual Anchor Length equation (La = Co * Lm), how can the value for Co be adjusted? Item #6: How to model horizontal buried piping going under roadways / railways? Item #7: How to model vertical Air Shafts - large diameter vertical underground piping ? Item #8: Why does adding a node point on s segment with soil settlement already defined make a big difference in the results ? Item #9: Alternative of performing buried piping analysis by using DeltaT equivalent in AutoPIPE? , Bentley different publication for performing verification / validation for buried safety related piping. Should this verification / validation include the alternative of using DeltaT equivalent temperature? Is this method valid for buried piping analysis? Item #10: Using AutoPIPE to determine pipe length needed for underground design item #11: Do we have to define the soil properties after the La (i.e., in Zone 3)? 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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Wiki Page: AutoPIPE FAQ - Soil
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Subarea: Original Author: Bentley Technical Support Group Question #1: What is an adequate spacing required for piping points (nodes) and soil points? Answer: There is no one answer to this question. See AutoPIPE's online help for suggested soil spring spacing based on Zone 1, Zone 2, or Zone 3 piping. These are only suggestions may need it increase/decrease soil points as required for convergence issues. Question #2: The more the nodes, some of the load cases (temperature, pressure and user-defined) do not converge Answer: If a model does not converge, please see the following AutoPIPE help section: Help > Contents> Search Tab> enter "Failure to Converge" (include the quotes), press List Topics button, double click on the selected topic from the list provided to see more information. Review the *.LOG file to understand where the failure is occuring and address the location. See omline help for details about the *.LOG file. Question #3: What is the most soil deformation that AutoPIPE can handle? Answer: Soil Deformations This can be a difficult problem, since the settlement is such a large soil deformation of 1600mm All beam theory piping analysis programs such as Autopipe, Caesar, pipeplus are based on small deformation theory and large displacements can give an ill-conditioned solution and erroneous results. As an example, large deformation across a large span of 200m. The maximum slope of the pipe may be of the order of 0.025 radians and the solution should be ok As a check that Autopipe can handle these large deformations use the following rule of thumb. Check that the maximum slope angle in radians of the deformed pipe = approx. sin (slope angle) then the solution should be ok. One method to simulate subsidence of known amount e.g 25mm see below. Set the yield P1 = 25 as shown below and K1 (initial) value = 0.001 and calculated soil stiffness = K2 (final) SOIL PROPERTIES Soil Initial K yield P Final K Yield disp ID Dirn (N/mm/mm ) (N/m ) (N/mm/mm ) (mm ) ------ ------- ---------- --------- ---------- ---------- SOIL1 Horiz. 6.540 699861.00 0.000 07.0118 Long 17.540 43859.00 0.000 2.5005 Vert Up 2.790 139303.00 0.000 49.9291 Vert Dn 0.001 25.00 23.030 24.9999 One method: If the maximum settlement is unknown, then model the soft waterlogged soil over the known span and known firmer soil at ends. Apply the over-burden sand weight as UDL load or vertical wind load (to simulate the pressure of the 4m sand) on the pipe and observe the deformation and check the resulting maximum slope. Note: ensure the final soil stiffness values K2 is not = 0 but a finite value e.g 0.001. The vertical down K2 value should be known (ie final soil conditions after settlement) and the P1 (soil yield ) value can be 'tweeked' to achieve the distance between the soft and final soil condition. Check that the actual pipe movement reaches the final soil condition otherwise the solution may become ill-conditioned. Maybe the sand has a influence on calculating the upward soil stiffness but this direction should not be important.. Question #4: Is there an error in the program. Why is the high stiffness values being used for the low Stiffness calculations and vise-versa Low values being used for the high stiffness calculations: Answer: This is not an error. The Yield Displacement is calculated via formula YD = P1/K1. However while calculating the K1 & P1 stiffness values we use low yield displacement values for high stiffness value and vice versa. This behavior is also described in the note Note: High yield disp. is used for low stiffness. Just below the Pipe direction selection on the dialog (shown below). For the parameters, the following rule is applied: 1. If the user updates a value in the low column, which is greater than high column value, the low column value is assigned to the high column value. 2. If the user updates a value in the high column, which is lower than the value in low column, there is no update to the low column. This behavior is missing from the online help and will be added in a future version of the program. Question #5: What is the best method to model soil settlement in AutoPIPE when 25.4mm (1 inch) of pipe settlement is required in the model when there is a probability of over -excavation and greater than 25.4mm (1 inch)? a.Impose and upward displacement on the support or b. A downwward displacement ont he soil Do soil springs act in both tension and compression? what is the besst way to model pipe settlement where over-excavation has occurred? Answer: In our opinion, approach (b) is better as the displacement is applied in a more discretized fashion than in (a). In AutoPIPE, imposed displacements can be applied only at points which are supported or buried. If the imposed displacements are applied as in (b), there will be compression in the soil springs below the pipe and tension in the soil springs above the pipe. Yes, soil springs act in tension as well as compression as per the assumption of bilinear behavior. Please refer to AutoPIPE help for more information. We think that it is more reasonable to retain the soil springs below and impose displacements on the soil points to model the soil settlement in areas of over-excavation. You may also consider using incline supports with a gap of 1" below the pipe so that the resistance of soil below the pipe is engaged after the pipe displaces 1" to close the gap (similar to scenario #2 in the figure below). However, the yielding of the soil cannot be modeled using this approach of using incline supports to model soil stiffness. Closer to the support, the pipe displacement is relatively less compared to mid-span. If large imposed displacements are modeled close to the support you might see spurious high stresses. ( WYMIWYG - what you model is what you get.) Yes, not modeling top soil might be a reasonable approach. As there is lesser restraint after removing these soil springs, the pipe support reactions are likely to be lesser as you have rightly observed. Question #6 What is the correct metric unit for the variable "f" at the bottom of the Edit Soil Properties window near Soil Overburden Loads? I am confused because the displayed imperial unit is psi, whereas the metric unit is N/mm. Answer : Yes, this is an oversight in the program (AutoPIPE V8i 09.06.00.xx and lower). If you convert the PSI value over to metric units the value displayed would have the units of N/mm^2. The development team is aware of this issue and will fix in a future version of the program. Question #7: Open the soil dialog screen and press Edit Soil Parameters button, set Calculation method = AutoPIPE, notice that lthe soil parameter "horizontal stiffness parameter ki" is always has the units of lb/in3 when the input units are set to SI. The lb/in3 units are the same in the ouput listing. The numerical value of the ki parameter is the same in the output listing regardless of units selected. is this an error? Answer: No it is not an error. Open the Edit Soil Parameters dialog screen, press the help button, under "AutoPIPE only parameters" select the hyperlink for "Horizontal Stiffness Parameter, ki" and read the online help. The reason for this is that there is no conversion in the unit files for lbs/in^3. We will require adding an additional unit in all our unit files to represent this lb/in3. Otherwise, the same value is used regardless of units selected in the model. Item #8: What type of discretized soil foundation is implemented in AutoPIPE (Example Winkler Soil Model, Filanenko Borodich Model, continuous model etc... Answer: To be added in the future. Item #9: How does imposing a support displacement effect the soil spring at the imposed support displacement and how does it effect adjacent springs ? Answer: Look at it this way, each support can be considered a spring with a base. The base is attached to the imaginary ground in the program. When you apply "Impose Support Displacement" to a support, the base will physically moved when a specific load case is applied during the analysis. These values are specified when inserting an "Impose Support Displacement". As mentioned in the online help, soil properties are essentially spring supports at intervals with the correct stiffness values. Therefore, "Impose Support Displacement" can be assigned and will affect Soil point locations. Furthermore, only those soil points that actually have "Imposed Support Displacement" assigned will move when the specified load case is applied during the analysis. This action will affect surrounding piping because the pipe is not made of bubble gum. Example: If a set of soils points between two node points have a 5 inch Impose Support Displacement assigned. When the indicated load case is analyzed, these soil point bases will try to moved the 5 inches, the rest of the adjacent soil springs will resist this movement but ultimately will be displaced by a fraction of that 5 inches until the impose support displacement no longer affects the adjacent soil spring. Typically the pipe will have a bell shape curve to it.
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Wiki Page: 02a. Load Case Descriptions in AutoPIPE
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Load Case Subarea: Original Author: Bentley Technical Support Group Comments, Questions, and Answers Item #1: For AutoPIPE 09.06.00.15, Under Load> Load Case Description, the description displayed for load case does not respect the units used in the model for example in joined file: t1 = 207 °c and load description displayed by autopipe is : 404.59999 °c, which the the temperature value in °f. the same issue occurs for pressure description. How to fix? Answer: This observation is correct and acknowledged by the development team to be fixed in the next version of the program AutoPIPE V8i 09.06.01.xx and higher. Workaround, manually update the text on the dialog screen. Item #2: Where does the description names print out in the output report? Answer: please see the following WIKI page about the Load Case Description sub-report section 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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Wiki Page: 02b. Static Analysis Sets in AutoPIPE
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Analysis Subarea: Original Author: Bentley Technical Support Group The Load> Static Analysis Sets command allows the user to define multiple static analyses (analysis sets) and provide references to these results from separate analyses during post-processing. Analyze > Static or will analyze all selected static analysis sets. The Static option in the Analyze menu enables the user to perform all the selected static analysis sets considering any scenarios of gravity and thermal expansion loads, plus wind loads and/or static earthquake loads if they have been defined. From inside AutoPIPE with a model opened, select Load> Static Analysis sets... after the screen appears press the " HELP " button for details on all the key features available on the dialog. To define loadcases to be added to a specific analysis set, highlight a row by left clicking the mouse on the first square in the row, the row should be highlighted black with white lettering, now left click the " Modify " button. In a moment the"Static Analysis Load Cases" dialog should appear. AutoPIPE only activates load case input fields for currently defined load cases. Again press the " HELP " button for details of features available on this dialog screen. "Static Analysis Sets" and "Static Analysis Load Cases" dialog Questions and Answers Item #1, Question: My results does not appear to be considering weight of conents in piping for the analysis? Answer: On the "Static Analysis Load Cases" dialog screen is a check box for "Contents", confirm this box is enabled (checked ON) for all analysis sets as desired. Enable this option to include the weight of the pipe contents in the analysis of the gravity (GR) load case. This will cause the program to consider the respective pipe properties settings for all the piping in the model. The calculation for weight of pipe contents is based on the individual pipe ID's: A. Inside diameter of a pipe B. Specific Gravity of Contents (based on water). C. Linear center line distance of a piping for a Pipe ID Each one of the 4 settings must be configured to correctly consider weight of contents in a piping systems for each Pipe ID and Analysis Set. Additional information is available to be reviewed in the Tools> Model Listing > Center of Gravity sub report. This option generates a section that reports weight and center of gravity coordinates for all the components in the model. The components are categorized as Valves, Flanges, Flexible Joints, Additional Weights, Pipes (includes straight runs, bends, tees and reducers), and Beams. Weight and center of gravity coordinates for Insulation, Insulation Cladding, Lining, and Contents are also reported as separate categories. Weight and center of gravity coordinates of different combinations of the categories are also reported (see online help for details on this report). Item #2, Comment: A new enhancement was added: Static / Dynamic Analysis Fluid Density Factor Item #3: Is it possible to export/store/import static analysis setting (load-case) I am working with Autopipe series 5 version 09.06.00.15. Answer: Bentley apologizes for the inconvenience but at this time AutoPIPE V8i 09.06.xx.xx and lower does nto have the ability to import/export Static analysis settings between models. Workaround: Open a model that has the correct Static analysis settings, save the file as a different name to protect the original model, using File> Insert AutoPIPE Model (DAT) command to import the model in, and update the Pressure / Temp / PipeID information as needed. L ogged enhancement: This issue has been logged under TFS-E82441: Add feature to Import / Export Static analysis sets from m odel. 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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Wiki Page: 02c. Dynamic Analysis in AutoPIPE
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Dynamic Analysis Subarea: Original Author: Bentley Technical Support Group Dynamic Analysis FAQ: Modal Response Spectrum Harmonic Time History Force Spectrum Note: see more information about AutoPIPE's Dynamic Data Storage files - (*.SPC, *.TIH, *.THL, *.FS, *.HMF) General Comments, Questions, and Answers Item #1: There is some confusion on how AutoPIPE closes the gap of a support in a dynamic analysis. It isn’t clear how this makes sense that the program will apply a support at a point where the pipe may not actually be moving enough lose the gap and to reach the support in reality. Any clarification on this? Answer : All AutoPIPE Dynamic analysis require that a modal analysis be performed. From AutoPIPE online help: AutoPIPE lumps the mass of the pipe, components and contents, etc. at the associated node point. This assumption yields a diagonal mass matrix with no mass coupling terms. There are three mass degrees of freedom per node. Rotational mass is ignored, except for points with eccentric weights, specified using the Insert/Xtra data/Weight command). At these points there may be up to three additional rotational masses and thus three additional mass degrees of freedom. It should be noted that for the eccentric weight, the coupling terms between the translation and rotational degrees of freedom are neglected. The structure is assumed to be linear and thus all gaps, friction and soil yielding is ignored. Item #2: Program should block dynamic analysis if static analysis set #1 not analyzed. Answer : This has been logged as a new enhancement under CAE-CR-10998. The internal setup of all the dynamic cases still rests with analysis set #1. If analysis set #1 is not analyzed with dynamic loads specified, your dynamic cases cannot be setup properly. Item #3 For V-Stop type support, like rod hanger, is AutoPIPE capable of deactivating the support in dynamic analysis in the analysis when it is active in static analysis? Answer : No, supports cannot be deactivated for a dynamic analysis. Only work around is to create a model with the support actually removed for dynamic analysis. Item #4 There are two types of global damping factor used in dynamic analysis of steel structures:1) % of critical damping and 2) % of structural damping. The default % value of critical damping used in Caesar II is 3%. Critical damping should be specified if the dynamic analysis is performed based on a combination of modal space (transformed from physical space to modal space through the natural frequencies and mode shapes) within the frequency range of interests. The structural damping coefficient of steel is typically 0.5%. This value is used when dynamic analysis is performed in physical space (the mathematical model represented by lumped mass and stiffness of piping members). We need to find out which type of dynamic analysis is being used. I think it is likely to be performed in modal space. Then I suggest to use 3% of critical damping - the default value used by Caesar II. If it is performed in physical space, then we should use 0.5% for structural damping. These values all stand for relatively small damping resistance from steel structures, which are known to have low damping resistance to dynamic loading. If there are special damping elements to help steel structure against dynamic movement, we should specify the damping coefficient for the specific element, not for the entire steel structure. Please note that we typically don't need to specify damping coefficient for snubbers, which should be considered as a rigid support during the quick pressure relief event. We believe Autopipe uses modal space. Can you, or your Time History Specialist, answer this question. Answer: Yes, a single damping ratio is applied to all modes. It has nothing to do with pipes or beams. Item #5: Dynamic load factor for safety valve transient open force has been given by ASME 31.1 Appendix II. We call it DLF ASME curve. And response force equals to gas exhaust reaction force plus DLF. In CAESAR, after input force-time curve, which is same as our Time History profile. Caesar can generate DLF spectrum. These spectrum are different from DLF ASME curve. Long duration and short duration generate different DLF curve. In AutoPIPE, it seems there is only ASME curve considered, and I can't find any result of those generated load factor with different period case in report. Could you give some instruction about this? Answer: This topic is covered in the official AutoPIPE Admin training class. Please contact your account manager for training options and schedule. Item #6: AutoPIPE's Solutions to Piping Vibrations: Types of Vibration AutoPIPE Solution 1. Mechanical: Harmonic Displacement Analysis A. Machinery Unbalanced Forces and Moments B. Structure Borne Vibrations 2. Pulsation: Harmonic Force Analysis A. Flow induced vibration due to compressors and pumps 3. Pressure Surge / Hydraulic Hammer Force Time History 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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Wiki Page: 02e. "Hydrotest" - AutoPIPE Load Case
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Loads Subarea: Original Author: Bentley Technical Support Group The Load> Hydrotest command enables the user to define the hydrotest conditions of a piping system. A hydrotest is a common method for testing the integrity of a piping system before it is put into service. In this test, the piping system is filled with pressurized water and checked for leakage, etc. The Hydrotest option permits a simulation of this scenario. Please note that the AutoPIPE Hydrotest option automatically converts all spring hangers into rigid supports to simulate the holding pin which is still in the spring hanger during the hydrotest. Comments, Questions, and Answers Item #1: Why are my V-stops not allowing lateral movement during a Hydrotest load case? Answer: From AutoPIPE online help: A non-linear static analysis cannot be performed on the hydrotest load case i.e. friction, support gaps and soil yielding are ignored. Item #2: Is there a method to perform a Hydrotest as a non-linear analysis? Answer: The following method overcomes the hydrotest load limitation in AutoPIPE (which cannot account for nonlinear gaps, friction and soil in the static analysis). Please see the following AutoPIPE help section: Help > Contents> Search Tab> enter "Hydrotest Non-linear Method" (include the quotes), press List Topics button, double click on the selected topic from the list provided to see more information. A new enhancement has been logged, TFS-E80939: Non linear analysis for hydrotest condition In AutoPIPE V8i 09.06.01.10 and higher, see the online help: Hydrotest Non-linear Method To enable hydrotest with gaps and friction, check the 'Non-linear' option for hydrotest load set in analysis sets dialog. Item #3: Why does the Hydrotest case show an Allowable K Factor of 0.9? Answer: Please see the following AutoPIPE help section: Help > Contents> Search Tab> enter "Hydrotest Loads" (include the quotes), press List Topics button, double click on the selected topic from the list provided to see more information. Item #4: Why are my Hydrotest results so high? Answer: Typically a hydro test is run at ambient temperature. B sure to check your Hydrotest load case configuration, see example below: In this example, Test temperature is set to T1. In some models, user set up a load case (i.e. T1) as their initial operating condition before the system is subjected to higher operating conditions. Regardless, review the Test Temperature Case that was specified on the dialog to be sure that temperature setting for all node points in the model are correct. Sometime, users have selected the wrong Temperature Load Case (ex. T4 instead of T2) on this dialog or that the Temperature is not uniform for the entire model (ex. node points L00 - M13 was set to 700 deg F instead of 70 deg F), all of which will cause wrong Hydrotest results. Furthermore, be sure that the Factor is as expected and not set to a higher value then inteded (default - 1.0). In addition, regardless if you have a ambient temperature case or not, setting Test Temperature Case = None, will use the temperature from the General Model Options dialog. Confirm this setting to be correct: 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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Wiki Page: 02g. "Wind" - AutoPIPE Load Case
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Load Case Subarea: Original Author: Bentley Technical Support Group Comments Questions and Answers about Wind loads Item #1, Comment: The Load> Wind command enables the user to define static wind load cases (W1 - W10) by generating wind pressure vs. (system) height profiles, or according to ASCE 7, or Uniform Building Code (UBC) requirements. After specifying a new wind load case, select the first cell in the left column to highlight the row and press the Modify button to see more settings for the specified Wind Load Type as indicated below: The wind force is applied as uniform loads in the local coordinate system of the straight pipe or bend element. The equivalent wind force is assumed to act through the centroid of the element. Wind loads will only be applied to piping segments that have "Applied Wind" checked on, and the load case checked On inside of the analysis set: Segment Tab on the input grids: Load> Static Analysis Sets> modify analysis set: Iten #2, Comment: Beam members are not subjected to wind loads, enhancement has been logged, CAE-CR-8199. Item #3, Comment: In order to exclude piping inside a building from wind loads, the piping inside should be entered as a separate segment(s) from the piping outside the building. With the model Input grid opened select the Segment Tab, see column labeled "Apply Wind", Applies wind load cases to the segment corresponding with the selected row. Enable (check ON) / Disable (check OFF) check boxes a required for segments listed in the model. Item #4, Comment: When specifying elevations wind load profile remember to check that ground is correctly defined on the main Wind screen. This applies also to wind loadings per ASCE-7 and UBC. Opening older models a warning message "negative elevations found" may indicate an incorrect wind loading across this model. If the Ground elevation for wind is entered with a value greater than the vertical coordinates of the model (i.e. the whole model is below ground) it will result in zero forces. Item #5, Question: The "negative value" used for wind ground elevation is confusing. Is there a simple explanation? Answer : AutoPIPE allows the user to create a piping system anywhere within the coordinate system constraints, how does the program know where the Ground level is unless you tell it! Ground level could be anywhere on the vertical axis: -4000 mm, -125 ft, 0 ft, +30 ft, +86645mm, anywhere, etc…. Just identify where it is and anything below that vertical level is considered underground. Item #6 Question: I would like to know if the wind profile can be input with Wind Velocity and Height data. It seems that, in the user interface in autopipe, Height and pressure has to be input in the wind profile. Answer : AutoPIPE does not accept velocity profile input at this time. AutopIPE does show the pressure profile and how it is calculated in load summary of the input listing. ASCE 7 defines wind speed as the nominal design 3-second gust wind speed at 33 ft (10 m) above ground for Exposure C category. Note that Kz value is 1.0 at 33 ft. So Kz gives the velocity profile per ASCE-7. You may use a similar procedure, entering your own velocity profile, to compute the pressure profile in Excel and then input in AutoPIPE. Refer to ASCE-7 for actual tables or equations. Item #7 Question: Do we need to specify the vector as -1 to specify the wind direction in -X direction. I understand that I need to make two cases for wind loading in east and west direction. similarly for earthquake cases we need to make a separate case? Answer : A. Please see the following AutoPIPE help section: Help> Contents> Contents Tab> Bentley AutoPIPE> FAQ> FAQ #24. In order to account for a negative wind direction: add an additional wind load case specifying the Inclined direction to be opposite of the initial wind direction. For instance: +X axis only : Wind direction = Global X -X axis only : Wind direction = inclined, Dx = -1, Dy = 0, DZ = 0 Item #8, Question: I am assuming the wind direction of "Inclined" in combination with the DX, DY, and DZ should take care of any user required eccentric, torsional, or pitched loading. Do you agree? Answer : Inclined wind will typically not give a eccentric loading since wind method (force or projected area) methods are applied uniformly at center of pipe An offset weight loading will give eccentric type loading or some offset force or moment loading. Item #9, Question: When setting up wind loading in Autopipe, should the Wind Shape Factor Multiplier be 1 or 0.7 when using the ASCE wind specification type. If you choose the ASCE wind specification type, this type has a force coefficient factor. I think this force coefficient factor may take the place of the wind shape factor multiplier when the ASCE wind specification type is used. Are we "double dipping" by using 0.7 for the Wind Shape Factor Multiplier and 0.7 for the Force Coefficient when using the ASCE wind specification type? Answer : The intent of Wind shape factor multiplier on the 1st screen of the Wind load case dialog is to provide a uniform factor that is applied to ALL wind load cases. However, AutoPIPE provides another more flexible method of applying this factor to the individual wind load cases; ASCE refers to this shape factor as "Force Coefficient Cf" and the UBC refers to it as "Pressure Coefficient Cq". Using these coefficient values on the individual load case dialogs enables the user to create a more accurate wind load based on the objects shape by providing different values for different wind directions (i.e. W1: Cf or Cq.= .7 for global X wind direction but W2: Cf or Cq = .9 for global Z wind direction). Using both Factor and coefficient values would reduce the wind load by the product of both values, which is incorrect. Therefore, either the Wind shape factor is modified and the coefficients are set to 1 or the Wind shape factor is set to 1 and the coefficients are modified. Item #10, Question: How to apply the same wind speed over the entire model? Answer : Specify a wind value using wind Profile command, and enter pressure which is calculated in the ASME 7. (example: 150mph = 41.706 psf) Item #11, Qu estion: In a model point A04 have a guide with 0.2" gap. I found that x-direction movement of GRTW1(GR+T1+W1, operating case) is 0.213". It means displacement exceeds gap allowance. Is it possible? Answer : Please see the following file " Nonlinear_wind_load_analysis.pdf ". It all depends on the specified load sequence or initial state. Defining nonlinear wind loads is much easier in AutoPIPE as all combinations are created for you automatically. Item #12, Question: I have been asked if the pressure used in a wind profile is the basic pressure i.e. acting on a plate is required in the input to allow AutoPIPE to adjust, or do I have to adjust the pressure for a pipe when inputting the figure? Answer : Yes for the wind profile you should calculate the pressure acting on a pipe or cylindrical shape including the shape factor. This pressure will be calculated and entered at different heights. Also enter the wind shape factor multiplier = 1.0. Note: Using UBC and ASCE-7 wind methods, the wind profile is automatically calculated. It is common practice to analyze at a minimum, wind loading for two non-concurrent directions typically X and Z (assuming Y vertical). However the wind could be acting in positive or negative directions like seismic so you may wish to analyze a minimum of four cases +/- X and +/- Z. If you have no gaps or non-linear features like friction then only two cases +X and +Z may only be necessary then create load combinations to include +/-X and +/-Z e.g. Gr+T1+W1 and Gr+T1-W1. Item #13, Question: What is the importance of annual probability of exceeding for Wind Calculation (say 1/500)?...What is the interpretation for this value and its relevance for determining wind load? Answer : The annual probability for exceedance of a 1/500 storm event is a 0.2% chance of getting or exceeding that storm event...this basically saying it's a 500 year storm which is only supposed to happen once every 500 years, but what it really means is there's a 1 in 500 chance, or 0.2%, of getting that storm event every year. But then you get a situation as seen in southern United States a few years ago where you get three 100-year storms in less than five years. AutoPIPE is not concerned with the frequency of a 1 in 500 year storm, what needs to be determine is what's the minimum design requirements to be modeled? Are the Wind loads entered into the model based on a 1, 10, 50, 100, 500 and etc. event? Refer to governing regulation, building code, or project documentation for wind loads to be applied in a model. Apply the respective wind loads as desired into the AutoPIPE model. Item #14, Q uestion: Prefer not to consider friction in any occasional case (i.e. Wind, Seismic, stc..). Is there any way to consider friction only the expansion case but not in any occasional Wind loads? Answer : Consider defining wind load cases in a separate analysis set and set the friction scale factor to zero in that analysis set. (Load> Static Analysis Sets> Enable "Gaps/Friction/Soil", with other load cases, press OK button, on the "Non-Linear Analysis settings, Friction scale factor = 0.0, press OK button). Item #15, Question: If an insulation thickness is provided for a member, does AutoPIPE adjust the effective diameter for wind/wave force calculations? Answer : Yes, Force coefficients (Cf) are given in Tables 6-10 for "Chimneys, Tanks and Similar Structures" in the ASCE 7-98 code. In Table 6-10, the force coefficient is a function of the h/D (= height/diameter) ratio and D*sqrt(qz). The default value "Automatic" will calculate Cf for each point based on D*sqrt(qz) as per Table 6-10 assuming round smooth pipes and a conservative h/D value of 25. The outside diameter D includes the pipe insulation thickness. The height h of chimneys and tanks in Table 6-10 would correspond to the pipe length facing the wind, not the pipe height. The pipe length is not considered in determining the Cf factor in AutoPIPE and instead a conservative value of h/D=25 is assumed. For most common pipe sizes, the shape factor is typically 0.7 when using "Automatic" option. Only very small diameters will have a shape factor of 1.2. The load summary will list calculated Kz, Cf and qz values as a function of height h. The Cf values in the load summary assume D = 1 ft. Item #16, Question: ASCE 7-10 Wind speeds Now Available on Web Answer : The wind speed site, www.atcouncil.org/windspeed , will be free for users. Users are encouraged to provide ATC with feedback about the site, using the Contact Us page, so that enhancements can be planned. Item #17, Comment: The following only affects AutoPIPE V8i 09.06.00.15 and will be fixed in the next new version 09.06.01.xx and higher: The Ground Elevation for Wind is always entered in Feet, regardless of the model units file specified on Tools> Model Options> General dialog . This can be confirmed with the Loads Summary Data Listing report using any metric units file (CAE-TR-11097). Item #18, Question: Why does the wind load appear that is not being applied to the model? Answer: Confirm the following: A. On the Wind dialog screen: 1. The piping where wind is being applied is above this user input value (default = 0.00 ft). any piping below this vertical location will assumed to be buried in soil or under water. 2. Wind shape factor is greater than 0.000 (default = 1.0) 3. Check box is enabled if all segments are exposed to wind, otherwise confirm segments applied to wind on the Segment Tab of the Input grids; "Wind" column. 4. There is at least one Wind load case being applied to the model. B. On the Wind Profile dialog screen: 1. Basic Wind Speed is greater than 0.000 2. Importance Factor is greater than 0.000 (default = 1.000) 3. Wind direction is specified as needed. C. Static Analysis Load case settings: Item #19, Question: W2 is entered as per image below, Select the OK button and reopen the same load case, AutoPIPE automatically changes the 1, 1 into 0.707, 0.707. WHY? Furthermore, if you change the value and reopen the dialog screen the original 0.707 settings are updated to radom values below 1.0. WHY? Answer: First while on this dialog, press the Help button and select the Hyperlink for "Wind Direction", when the help opens for this specific topic, the answer to the first question is answered by the last sentence of the paragraph "Upon saving the inclined direction vector..." Second, to answer why the program is m ysteriously updated to some values other than 1.0 or 0.707; answer, because the value was not correctly accepted by the dialog and the previous value is still being applied. On this and other dialogs, after updated a dialog field value, press the TAB keyboard key before using the mouse to select the OK button. Otherwise the program will ignore the new settings and use the original values that was originally entered before the update. Again, solution read the online help to know why the values of Dx=1.0 and Dy = 1.0 are being changed, and always use the TAB keyboard key after entering any data into any dialog. Item #20: ASCE7 - 2010 Wind loads are Service or Ultimate loads in AutoPIPE 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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Wiki Page: 02h. "Snow Load" - AutoPIPE Load Case
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Subarea: Original Author: Bentley Technical Support Group The Snow Load dialog gives the user the ability to apply snow loads to segments of the model. When snow is applied, AutoPIPE creates a load in direction of gravity (simulating the real effects of snow in direct contact on a pipe), and can be defined through one of three methods. Weight/Length Weight/Area Density Comments, Questions, and Answers Item #1: On the Snow Load dialog screen, how exactly is the snow load calculated for weight / Length = 0.5 lbs/in for both a 2 inch dia pipe and 12 inch dia pipe that are both 1 ft long piece of pipe. Answer: The answers would be identical because the pipe diameters are not considered. In this example, the user is entering the weight of snow per length of pipe that already considers a pipe diameter or another words: Weight of snow for the 1 foot length of 2 inch dia pipe: (0.5 lbs / inch) * (12 inch) = 6 lbs of snow Weight of snow for the 1 foot length of 12 inch dia pipe: (0.5 lbs / inch) * (12 inch) = 6 lbs of snow Note: 1. AutoPIPE currently only consider the horizontal component of projected pipe area for snow loading . Another words, as the vertical angle increases only the horizontal length component of the angle will be used to calculate the snow load. For piping on the vertical axis, the program will automatically remove snow load that has been applied. 2. For dialog options Method = "Weight / Area" or "Density", the projected area is used in calculating the snow load; horizontal length component of the angle multiplied by the pipe's outer diameter. 3. Snow loads, like wind loads, are not currently applied to beams. This is has been logged as an enhancement for a future version. 4. Currently, AutoPIPE V8i 09.06.01.xx and lower does not handle snow loading for non-linear analysis and is not accurately nor realistically applied to non-linear models. As a work around, apply uniformly distributed loads along the relevant segments with the expected linear forces and combine this distributed load with a wind case. Item #2: How do i delete the snow load from an AutoPIPE model? Answer: The easiest method of removing snow load from a model is to perform the following: 1. On the Segment tab of the input grid, un-check snow load for all segments. 2. Under Load> Snow> regardless of Snow load Method, make all values 0.00. 3. From the analysis set dialog screen, for each analysis set, remove check mark next to the Snow Case. Run the analysis, and verify in the complete analysis report that no snow load was analyzed. See Also Bentley AutoPIPE External Links Bentley Technical Support KnowledgeBase Bentley LEARN Server Comments or Corrections?
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Wiki Page: 02i. "Thermal Bowing" - AutoPIPE Load Case
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: loads Subarea: Original Author: Bentley Technical Support Group Comments, Questions, and Answers: Item #1: Partially Filled Liquid Pipelines or Hot Sun Exposed Pipes Item #2: How can i apply thermal bowing on only analysis set 3. When i check the thermal bowing option for analysis set 3 it is also checked for the other analysis set. this occurs in spite of the fact that i specified : apply thermal bowing to thermal case t2 only in thermal bowing definition window. Answer : Thermal bowing application or non-application is selected once and applies to all analysis sets. It gets associated with the load case you identify on thermal bowing dialog and after that it can be controlled at the segment level i.e. determine on which segments to apply and which ones to ignore/skip. This may be confusing to some users as they enable it inside of an analysis set and there is no warning / message that it will be applied to ALL analysis sets. Again, the main confusion for the users is because the control to enable/disable thermal bowing is provided at static analysis set dialog even though it is not controlled at analysis set level and implies directly to a load case. The original intent was to turn it on an off during all analysis sets and not individual set. The CAE development team is considering one or more of the following options: A. Consider making Thermal Bowing an analysis set specific option B. Add a warning that this applies to all analysis sets. Workaround: The workaround at the moment seems easy to only use thermal bowing with its own thermal case 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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Wiki Page: 02n. "Harmonic" - AutoPIPE Load case
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: Load Case Subarea: Original Author: Bentley Technical Support Group Comments, Questions, and Answers: Item #1: We are analyzing harmonic load with known Frequencies and Forces. Is there a way we can convert frequency domain to time domain in order to apply time history load? Answer: I apologize for the inconvenience, however AutoPIPE ( v.09.06.xx.xx and lower) does not have this ability at this time. 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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Wiki Page: 02p. "Time History" (M1-M50) - AutoPIPE Load Case
Applies To Product(s): AutoPIPE, Version(s): 2004, XM, & V8i Environment: N/A Area: load case Subarea: Original Author: Bentley Technical Support Group Comments, Questions, and Answers on Fluid Transient Load case Dialog screen: Note: see additional comments about Time history analysis in AutoPIPE on the following WIKI's: Water Hammer (Time History) Example - Modeling Approach in AutoPIPE Dynamic Analysis - Time History load case in AutoPIPE Item #1: On the Load> Time History Location dialog screen, change value at node (ex. C14 N) from Dy = -1 to Dy = -10 and there is no change in the results, but if change Dy = 0, there is a change in the results. Why? Answer: From the online help: DX/DY/DZ Specify the direction cosines or offsets of the time history load (i.e., values of 1,0,0 would specify the X-direction as the direction at which the time history load is applied. Therefore, changing Dx =0, Dy = -1, Dz = 0, to Dx =0, Dy = -10, Dz = 0, has no affect on the direction cosines, the load is still going to be applied in the -ve Dy direction regardless if Dy in this case is any number -1 to -infinity. In addition, by setting Dx =0, Dy = -1, Dz = 0, to Dx =0, Dy = 0, Dz = 0, will have a significant change on the results as there is now no directional cosine specified for the load. If there was another direction with a value, Dx =1, Dy = -1, Dz = 0, to Dx =1, Dy = -10, Dz = 0, is a significant change in the directional cosine. Thus changing the results. . 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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