After clicking on 'Properties>Sections' in the navigation treeview, follow the steps to define the Sections. You can use the collapsed documentation page below for more information on the explanations of each parameter.
Properties
The following properties will be used to compute the stiffness of the beams or trusses in the finite element analysis model:
Material: The material assigned to the section will be used to compute values such as the EI, GI, and EA for beam elements in the finite element analysis model.
Area: The gross cross-sectional area of the section is used for axial stiffness, and it is the only property needed for truss and cable elements since they have only axial stiffness. Rebars and tendons do not affect the computation of the area.
Shear Area Y: The shear areas Ay correspond to transverse shear in the xy planes with corresponding transverse shear stiffness as Ay*G. Rebars and tendons do not affect the computation of the shear area.
Shear Area Z: The shear areas Az correspond to transverse shear in the xz planes with corresponding transverse shear stiffness as Az*G. Rebars and tendons do not affect the computation of the shear area.
Torsion Constant: The torsional constant refers to the area moment about the member x-axis, and it is used to determine the torsional stiffness of the member. Rebars and tendons do not affect the computation of the torsion constant.
Inertia Y: The area moments of inertia Iyy about the member local y are used for the bending stiffness of beam elements. Rebars and tendons do not affect the computation of the inertia.
Inertia Z: The area moments of inertia Izz about the member local z are used for the bending stiffness of beam elements. Rebars and tendons do not affect the computation of the inertia.
Inertia ZY: The product of inertia (POI) describes an object's imbalance relative to a defined set of coordinate axes, but the current finite element formulation of feline in OpenBrIM does not consider Iyz (POI). When POI is not equal to 0 and the user rotates the section using the beta angle or the section editor, it can result in two different finite element analysis results. To ensure better representation of analytical problems, it is recommended to keep the value of Izy close to zero with the current feline formulation.
Compute Properties From Shape?[Yes/No]: When a section has geometry, selecting "Compute Properties from Shape Parameters" as "Yes" will automatically calculate the sectional properties. The properties shown in unlocked view will not be used. Users can view the computed parameters by using the lock icon. The inputs entered by the user for the area, shear area, inertia, torsional constant etc will only be used if "Compute Properties from Shape Parameters" is set to "No". Lastly, if the section does not have any geometry, the entered parameters will be used for the analysis, regardless of the "Compute Properties from Shape Parameters" setting. To summarize, in order to view the sectional properties that are used in the finite element analysis, users should use the lock icon. The sectional properties displayed with the lock icon will represent the properties used in the analysis.
Has Geometry? (readonly): If a section has shapes defined in the section editor, the "Has Geometry" property will be set to "Yes". Users can confirm this by accessing the three-dot menu and checking the shape from the section editor.
Assigned? (readonly):When a section is assigned to finite elements, the "Assigned" property will be marked as "Yes", although there may be cases where the section is also assigned to library components and indirectly used in the design and FEA process.
Is Composite? (readonly): A section will be defined as composite if the section is produced by a combination of two or more shapes and has the different materials assigned.
FAQ: Rigid Material and Section Definition
More Properties
Gross Area: The gross area of a section refers to the total cross-sectional area bounded by its outermost layers, including any voids or cavities within those boundaries. It is calculated without considering any deductions for holes, openings, or other internal features.
Radius of Gyration Y: The radius of gyration is a property in structural engineering that describes the distribution of cross-sectional area around a section's centroidal axis relative to its mass, and it is calculated using the section's area and moment of inertia. Although it does not affect analysis, OpenBrIM may use it for code check purposes in certain cases.
Radius of Gyration Z: The radius of gyration is a property in structural engineering that describes the distribution of cross-sectional area around a section's centroidal axis relative to its mass, and it is calculated using the section's area and moment of inertia. Although it does not affect analysis, OpenBrIM may use it for code check purposes in certain cases.
Centroid Location Y: Centroid of section. When defining sections in the Section Editor, the COG of the section may not align with the member reference x-axis, resulting in a centroid offset. To calculate the member offsets in such cases, a logic that includes both the centroid offset and the member end offset is used. A non-zero value for the centroid offset changes the member end offset values used in the feline stiffness matrix computation, thus affecting the FEA.
Centroid Location Z: Centroid of section. When defining sections in the Section Editor, the COG of the section may not align with the member reference x-axis, resulting in a centroid offset. To calculate the member offsets in such cases, a logic that includes both the centroid offset and the member end offset is used. A non-zero value for the centroid offset changes the member end offset values used in the feline stiffness matrix computation, thus affecting the FEA.
Shear Center Y: The shear center is used in certain design calculations, but it does not affect the results of the finite element analysis.
Shear Center Z: The shear center is used in certain design calculations, but it does not affect the results of the finite element analysis.
Perimeter: The perimeter of a section is utilized in some design calculations, but it typically does not impact the results of the finite element analysis. However, in cases where time-dependent staged construction analysis is employed with the CEB-FIP code, the perimeter may affect the coefficient computations per the CEB-FIP 1990 standard.
Warping Constant: The warping constant is used for design purposes and does not affect the finite element analysis results.
Non-prismatic Variation Direction[X/Y/Z/None]: The user only needs to input this value if they want to define nonprismatic variation. If the user intends to define nonprismatic variation, this input is optional. The nonprismatic variation direction X should be used for sections assigned to elements following the alignment in the longitudinal direction, such as girders. The Y direction should be used for sections assigned to elements in the transverse direction, such as pier caps, and the Z direction should be used for elements in the vertical direction, such as pier columns.
Extent
The Extent Tab’s parameters can be used to further define the section geometry.
Pos. of Neg. Edge Y: For a visual representation of Pos. of Neg. Edge Y , refer to the figure below.
Pos. of Pos. Edge Y: For a visual representation of Pos. of Pos. Edge Y , refer to the figure below.
Pos. of Neg. Edge Z: For a visual representation of Pos. of Neg. Edge Z , refer to the figure below.
Pos. of Pos. Edge Z: For a visual representation of Pos. of Pos. Edge Z , refer to the figure below.
Flexure Capacity of a Section
For the defined sections, it is possible to have flexure capacity calculated and observe the section's behavior accordingly. To achieve this, several steps must be followed.
The same approach can be used to generate the Moment-Curvature Curve of a section and the Interaction Diagram of a section.
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RigidSection RigidMaterial 6400.0000 6400.0000 6400.0000 3413333.3333 3413333.3333 3413333.3333 0.0000 YES NO NO NO |  |
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Completed Sections definitions are illustrated below.
Parameters >
| 1 | For any section, it is possible to add or change parameters that are used in geometry definitions. Click on three-dots icon to open Parameters tab. |  |
| 2 | In this menu, you can change the value of the parameter or add a new one to be used in the Section Editor. |  |
| 3 | These parameters can be utilized in the Section Editor → Points Spreadsheet, which is explained in the subsequent sections. |
Properties >
Follow the next steps to set rebar detailing for PierCapRec_Mid.
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Enter:
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Profile: ASTMA615No9 Material: A615_60 Click Apply. |  |
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0.0000 0.0000 -45.0000 45.0000 45.0000 45.0000 |  |
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Enter:
Click Add. | |
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Profile: ASTMA615No8 Material: A615_60 Click Apply. | |
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0.0000 0.0000 -41.7500 -41.7500 41.7500 -41.7500 | |
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Follow the next steps to set rebar detailing for PierCapRec_Taper.
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Profile: ASTMA615No9 Material: A615_60 |  |
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0.0000 0.0000 -41.6220 20.0000 -39.3720 20.0000 | |
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2 0.0000 0.0000 -25.8680 20.0000 -28.1240 20.0000 3 0.0000 0.0000 -12.3700 20.0000 -14.6260 20.0000 4 0.0000 0.0000 -1.1280 20.0000 1.1280 20.0000 5 0.0000 0.0000 12.3700 20.0000 14.6260 20.0000 6 0.0000 0.0000 25.8680 20.0000 28.1240 20.0000 7 0.0000 0.0000 41.6220 20.0000 39.3720 20.0000 |  |
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Enter:
Click Add. | |
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Profile: ASTMA615No8 Material: A615_60 Click Apply. | |
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0.0000 0.0000 -41.7500 -20.0000 41.7500 -20.0000 | |
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Follow the next steps to set rebar detailing for PierColumnRec.
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Enter:
Click Add. |  |
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Profile: ASTMA615No9 Material: A615_60 Click Apply. |  |
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0.0000 0.0000 -35.0000 35.0000 35.0000 35.0000 | |
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Enter:
Click Add. | |
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Profile: ASTMA615No9 Material: A615_60 Click Apply. | |
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0.0000 0.0000 -35.0000 -35.0000 35.0000 -35.0000 | |
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Enter:
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Profile: ASTMA615No9 Material: A615_60 Click Apply. | |
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0.0000 0.0000 -35.0000 27.3780 -35.0000 -27.3780 | |
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Enter:
Click Add. | |
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Profile: ASTMA615No9 Material: A615_60 Click Apply. | |
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0.0000 0.0000 35.0000 27.3780 35.0000 -27.3780 | |
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Follow the next steps to create different section definitions that OpenBrIM provides.
| 1 | Enter a Section under Name. |   |
| 2 | Import a material. | |
| 3 | From any column of the added row, click on three-dots icon to open Section Editor panel. | 
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| 4 | You can open the tab which includes Polygon, Template, Rebar and Tendon by clicking Shapes icon at the left top side of the screen. | 
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| 5 | To define a polygon shape, click to Polygon at Shapes tab, then click the coordinates of an arbitrary shape. | -20221006-141301.png?version=1&modificationDate=1665065590914&cacheVersion=1&api=v2)
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| 6 | You can rechange the locations by clicking ‘Points Spreadsheet’ after you assign the shape.  | |
| 7 | To utilize a Template click Template. | -20221006-142008.png?version=1&modificationDate=1665066020200&cacheVersion=1&api=v2) |
| 8 | If you don’t have a material already imported (or defined as custom), you can import by clicking Import. If you have, just select it from the Material drop-down. | -20221006-142433.png?version=1&modificationDate=1665066281224&cacheVersion=1&api=v2)
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| 9 | Edit dimensions of the shape to create the section. Click to Import. | -20221006-142448.png?version=1&modificationDate=1665066296420&cacheVersion=1&api=v2)
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| 10 | After you import the section, it will show up on the section editor. | 
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| 11 | To add rebars to your section click Rebar at the Shapes tab. | -20221006-142614.png?version=1&modificationDate=1665066381455&cacheVersion=1&api=v2) |
| 12 | If you don’t have a Rebar definition in your project, you will get a popup to import one. Just click OK and continue. |  |
| 13 | Select your asset from OpenBrIM Database for rebar profile and click Import. | 
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| 14 | By clicking Line Layout, you can switch the layout of the rebar as Line, or Circular. | -20221006-143057.png?version=1&modificationDate=1665066665741&cacheVersion=1&api=v2) |
| 15 | Let’s stay on Line Layout, and enter rebar layout input data. | |
| 16 | After you click Add, you should click the start and end location points of the section. No need to be exact in locations, they can be edited later. | -20221006-145238.png?version=2&modificationDate=1665067995346&cacheVersion=1&api=v2)
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| 17 | After clicking end location, Edit Linear Rebar Layout window appears. | -20221006-145456.png?version=1&modificationDate=1665068115619&cacheVersion=1&api=v2)
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| 18 | Edit Linear Rebar Layout. | -20221006-145651.png?version=1&modificationDate=1665068230049&cacheVersion=1&api=v2)
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| 19 | If you don’t have a rebar material already imported (or defined as custom), you can import by clicking Import . If you have, just select it from the Material drop-down. |  |
| 20 | After Apply all the entered data in Edit Linear/Circular Rebar Layout window, you can change the location of the rebar layout at the analytical coordinate system by clicking Points Spreadsheet under three-dots. | -20221006-145837.png?version=1&modificationDate=1665068328109&cacheVersion=1&api=v2)
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| 21 | Applying the same procedure, you can insert rebars at top and bottom. This time number of rows is set to 1 and rebar layouts placed twice for top and bottom, respectively. |   |
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| 23 | To add tendon to your section click Tendon at the Shapes tab. | -20221006-150314.png?version=2&modificationDate=1665068607108&cacheVersion=1&api=v2)
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| 24 | After you import the material for the tendon and add the tendon to your section, you can rearrange the coordinates of the tendon. | -20221006-150521.png?version=1&modificationDate=1665068728526&cacheVersion=1&api=v2)
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| 25 | Also, you can use a parametric relationship as input for Y1=d/2-10 (d = depth of the section). The position of the rebar depends on the section depth. | 
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To see an example of rebar definition for a section, you can refer to the video below. The PierCapRec_Mid rebar definition is included.
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