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AutoPIPE Wiki 03. Beam Structure modeling in AutoPIPE
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    • -Pipe and Vessel Stress Analysis - Wiki
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          • .b - Cuts: Cold Spring Modeling example in AutoPIPE
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          • .k - Pipes - Modeling in AutoPIPE
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          • +01a. Model Different Types of PIPING in AutoPIPE
          • +01b.Model Different Types of PIPING Components - AutoPIPE
          • +01c. Model Non-metallic Plastic Piping (i.e. Plastic, PVC, PP, PPR, HDPE, PE, FRP, GRP, etc.)
          • +01d. Model a Ring Main (circular header) with AutoPIPE
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          • +02a. Model Subsea (Underwater) Piping - AutoPIPE
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          • +03a. Model Rotating Equipment: Pumps, Compressor, Turbine in AutoPIPE
          • +03b. Modeling Vessel / Nozzles in AutoPIPE
          • -03c. Modeling Support and Beam Structures in AutoPIPE
            • +01. Different Types of Supports In AutoPIPE?
            • +02. Available AutoPIPE Help Example Methods for Modeling Supports with related FAQ's.
            • -03. Beam Structure modeling in AutoPIPE
              • +00. Specific questions related to "Beam Properties" Dialog in AutoPIPE
              • 01. How to insert / modify a beam in an AutoPIPE model?
              • 02. Model piping held by 2 rigid structural beam supports members in AutoPIPE
              • 03. How to model a vertically pipe supported by a Pipe clamp and spring supports as shown below:
              • 04. How to model a U-bolt in AutoPIPE?
              • 05. How to Model Equipment Supported by Steel and Springs?
              • 06. How to model a support that moves with the tank/vessel?
              • 07. Modeling the same beam 3 different ways in AutoPIPE
              • +08. How to model a Trunnion welded structural pipe support in AutoPIPE?
              • 09. How to model a Trapeze / Beam supported pipe in AutoPIPE?
              • 10. How to model a vertical vessel held in place by 4 supports in AutoPIPE?
            • +04. General FAQ's about Supports and Beams in AutoPIPE
          • +03d. Modeling Anchors in AutoPIPE
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          • 04m. Model Cryogenic piping in AutoPIPE
          • 04n. How to model / perform Creep Analysis with AutoPIPE?
          • 04o. How to model a Smart Pig going thru the Pipeline in AutoPIPE?
          • 04p. Input node point displacement / acceleration from field data in AutoPIPE?
          • 04r. How to model a Relief Valve thrust force in an AutoPIPE model?
          • 04s. How to model a thrust via a flowing fluid (i.e. impulse-momentum change equation) to an AutoPIPE model?
          • 04t. How to model the load on a piping system installed on a ship, Rig, or FPSO (Floating Production Storage and Offloading) when using AutoPIPE?
          • +05a. Cut / Copy / Paste / Rotate / Move / Stretch Commands
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          • +05d. Delete Command in AutoPIPE
          • 06a. Modeling approach to account for piping beyond modeled piping
          • 06b. Apply More Than 1 Piping Code In an AutoPIPE Model
          • 06c. How to model a liquid (water) / gas (foam or air) Fire Protection piping system in AutoPIPE?
          • 06d. How to model vaporization / boiling of liquid in pipe that causes a pressure wave to travel up the line in AutoPIPE?
          • 06e. How to model a pipe riser (vertical pipe) to correctly account for GR weight on each floor support in AutoPIPE
          • 06f. Modeling a Manway / access port in a pipe sidewall using AutoPIPE
          • 06g. Using load case displacement as a new starting point for analysis in AutoPIPE?
          • 06h. How to model node point shared by more than 1 model?
          • 06i. How to model miss aligned pipe pulled back into original position using AutoPIPE?
          • 06j. How to model lifting pipe segment(s) using AutoPIPE?
          • 06k. How to model piping systems not aligned with the global axis using AutoPIPE?
          • 7a. Modeling scenario using AutoPIPE: hot tapping a pipeline under operating condition, stresses in system after plant shutdown
          • 7b. Model Joule-Thomson effect and solving the transient heat transfer through the thickness of the pipe using AutoPIPE?
          • Tutorial - Water Hammer (Time History) Example - Modeling Approach in AutoPIPE
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     Questions about this article, topic, or product? Click here. 

    03. Beam Structure modeling in AutoPIPE

    Overview

    The mass and flexibility of structural supports can have a profound impact on the piping stress analysis. In many instances, if the support structure deflects only a fraction of an inch, it can affect piping moments to the extent where hangers can be eliminated, and/or piping loads on equipment nozzles and supports can be significantly altered. In addition, consideration of structural support flexibilities changes the natural frequencies of the piping system.

    Modeling pipe/structure interaction as part of piping stress analysis

    Despite the fact that structural support flexibilities can have a significant impact on piping loads and stresses, most piping engineers do not consider these flexibilities in their piping stress, analysis. Typically, structural supports are modeled as simple supports such as rigid guides, vertical stops, line stops, etc. with no consideration given to the flexibility of the support itself. Although AutoPIPE allows engineers to input a stiffness as part of the support element, the piping engineer often does not have convenient access to structural support details needed to calculate support stiffness'. As a result, the support is typically treated as rigid.

    As an alternative to using simple supports, AutoPIPE enables engineers to easily build the support structure into the piping model in order to consider pipe/structure interaction. The structural modeling is done within the piping model itself and takes advantage of AutoPIPE's graphical user interface, Using AutoPIPE's ability to graphically copy & paste between separate jobs or within the same job, users can now create libraries of common support structures and paste them into their new model in seconds. We will explain later AutoPIPE's unique abilities in defining the relationship between piping and structural steel.

    AutoPIPE users are not burdened with going back and forth between separate programs or batch files to model support structures. Currently, AutoPIPE supports the American Institute of Steel Construction cross, sections as well as a material properties library for common structural steel materials. Once a cross section has been interactively selected, the user immediately sees the cross sectional properties with moments of inertia from the AutoPIPE structural database as well as the steel material properties. Nonstandard cross sections or cross sectional properties for International steel shapes can be entered as nonstandard or saved in the AutoPIPE database. AutoPIPE's structural steel analysis provides beta angle options, moment releases for pinned joints, and rigid end length options. Users see the structural model graphically as it is being built.

    Once the support structure has been created, users can define the connection between piping and structural steel using one of AutoPIPE's 2 point supports such as a guide or a vertical stop. A user can, for example, define the support connection between node B10 on his piping system and node 21 on his support frame by connecting them with a guide from B10 to 21. From there, the user can place gaps in any direction in the event that the pipe would lift off or move, and can also input friction. The flexibility of the support structure, including friction loads, will then be considered as part of the piping analysis. In addition to piping analysis results, users can also review beam deflections, beam forces and moments.

    AutoPIPE incorporates Timoshenko beam theory for calculating the stiffness matrices. The assumptions associated with using these type of beam element are:

    i. Plane section remain plane but not necessarily perpendicular to the centerline of the beam
    ii. Effects of shear deformation are included
    iii. Only valid for small deformations (the cross section or properties of the beam are not affected by the deformations)
    iv. Only valid for stresses under elastic range (no plastic deformation)
    v. Modulus is considered the same in tension and compression

    The accuracy of an analysis with combined beam and piping will depend on the assumptions made for the small displacement theory and whether these assumptions would cause an error which is with acceptable limits:

    a. Displacement is small in comparison to the smallest dimension of the structure
    b. Rotations are small and square of rotations is much smaller than unity
    c. The strain is small and square of strain can be neglected
    d. The equations written for the un-deformed configuration of the structure can be assumed to be valid for the deformed configuration

    Comparison of the results for the simplest form of the problem (something like a cantilever beam), with results from another analysis incorporating more refined analysis method. If the error between the analysis results are within an acceptable limits,  the results may be assumed to be within the limitations or within a range for which the results are acceptable. 

    Some specific technical references / resources discussing the above topics which are relevant to how AutoPIPE has specifically implemented its beam element are available in AutoPIPE's Help> Reference Information section>. SAP IV technical manual is available online, which acted as the basis for AutoPIPE analysis engine. The general implementation for the stiffness matrix for the Timoshenko beam theory is available in text books, consider online search for these texts.. 

    Limitations:

    For a complete list of beam limitations in a specific version of AutoPIPE, see the following AutoPIPE help section:

    Help > Contents> Contents Tab> Bentley AutoPIPE> Command Reference> Insert command> Structure Group> Adding, modifying, and deleting beams

    Note: for all other loading not listed under "Beam Members CANNOT" will be applied to beams structures. Also, recall that for some loads such as Static Seismic and Response spectrum, these loads are applied to Support and Anchor components. Therefore, like pipe, Beams and Beam structures will be affected by these loads through Support and Anchor locations. 

    Viewing Beams:

    Use the following command to control the viewing / hiding of beam components:

    a. Hide Selected Beam,

    command location:

    - Home > Operations > Beams > Hide Selected Beam(s) 

    - Show > Hide > Selected Beams 

    b. Hide Unselected Beam

    command locations: 

    - Home > Operations > Beams > Hide Unselected Beam(s)

    - Show > Hide > Un-Selected Beams

    c. Hide / Show Components

    command location:

    - View > Hide > Components 

    d. Show All Beam(s)

    command locations: 

    - Home > Operations > Beams > Show All Beam(s)

    - Show > Show > Beams

    Comments, Questions, and Answers about modeling Beam / Frames

    Item #0: Questions about Beam dialog

    Item #1: Insert a beam

    questions related to:

    a. Beam Properties dialog

    b. Insert Beam dialog

    Item #2: Piping held by 2 rigid beam structural supports members

    Item #3: Vertically pipe supported by a Pipe clamp and spring:

    Item #4: U-bolt

    Item #5: Equipment Supported by Steel and Springs

    Item #6: Support moves with the tank/vessel thermal growth

    Item #7: Model beam 3 different ways

    Item #8: Trunnion welded structural pipe support

    Item #9: Trapeze / Beam support

    Item #10: Vertical vessel held in place by 4 supports


     

    See Also

    Modeling Support and Beam Structures

    Bentley AutoPIPE

    • AutoPIPE
    • beam
    • Modeling
    • support
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    • Mike Dattilio Created by Bentley Colleague Mike Dattilio
    • When: Fri, Dec 12 2014 2:26 PM
    • Mike Dattilio Last revision by Bentley Colleague Mike Dattilio
    • When: Wed, Sep 9 2020 10:59 AM
    • Revisions: 26
    • Comments: 0
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