Column Tendon [SIG]
Layout
Column: Specify the column in which the tendon will be placed.
Section Reference Point [Center of the Section]: For the column tendons, the reference point is the center of the section.
Layout Input Method [Path Data/Tabular Data]: There is two possible ways to input tendon geometry: Tabular Data and Path Data. Both of these methods take their reference from the selected structural object, the **Column'**s reference point. User needs to specify points on each row and these points are combined by OpenBrIM to create a tendon line.
Tabular Data: This cell is activated when Layout Input Method is selected as Tabular Data. If Layout Input Method is selected as Path Data this cell is displayed as “N/A”. The parameters of Tabular Data use the local coordinate system of the object. Refer to the figure below for the orientation of the directions.
Longitudinal Distance: This parameter can be used to specify changes in tendon locations in the transverse and vertical directions. At least two rows of definitions are required, representing the start and end points of the column tendon.
Transverse Offset: The offset value for both local and global coordinate systems, in the transverse direction for both axes, can be specified using this parameter. The generation of the object will be adjusted accordingly.
Vertical Offset: The vertical offset corresponds to the alignment's longitudinal direction and the element's vertical direction. This offset can be specified using this parameter.
Radius: Set the point’s radius of curve.
Transverse Tendon Path: When the parameter Layout Input Method is set to Path Data, the following parameters related to the transverse tendon path can be specified. If not, these options will be marked as Not Applicable (N/A).
Distance: This parameter specifies the distance along the tendon for which further definitions will be made.
Transverse Offset: Specify the transverse offset value for the tendon’s point. A positive value indicates that the tendon moves to the right when looking upstream along the PGL (Profile Grade Line).
Variation Type (from next point): Options include [None/Linear/Parabola/Circular/Polynomial Fit].
Curvature Type (for Parabola and Circular): Options include [Concave Up/Concave Down]. This parameter can be specified only if the variation type is set to Circular or Parabola.
Radius (for Circular): If the curvature type is defined as Circular, a radius value can be specified for the tendon.
Start Grade (for Polynomial Fit): Set the initial grade of the fitted polynomial line between the point in the current row and the next row. This option is applicable only to the Polynomial Fit variation type.
End Grade (for Polynomial Fit): Set the end grade of the fitted polynomial line between the point in the current row and the next row. This option is applicable only to the Polynomial Fit variation type.
Vertical Tendon Path: When the parameter Layout Input Method is set to Path Data, the following parameters related to the vertical tendon path can be specified. If not, these options will be marked as Not Applicable (N/A).
Distance: This parameter specifies the distance along the tendon for which further definitions will be made.
Vertical Offset: Specify value here, if applicable.
Variation Type (from next point): Options include [None/Linear/Parabola/Circular/Polynomial Fit].
Curvature Type (for Parabola and Circular): Options include [Concave Up/Concave Down].
Radius (for Circular): Specify value here, if applicable.
Start Grade (for Polynomial Fit): Set the initial grade of the fitted polynomial line between the point in the current row and the next row. This option is applicable only to the Polynomial Fit variation type.
End Grade (for Polynomial Fit): Set the end grade of the fitted polynomial line between the point in the current row and the next row. This option is applicable only to the Polynomial Fit variation type.
Local Coord. X Offset: This parameter defines the offset value for the tendon in the local X direction.
Local Coord. Y Offset: This parameter defines the offset value for the tendon in the local Y direction. For visual representation, refer to the figure below.
Local Coord. Z Offset: This parameter defines the offset value for the tendon in the local Z direction. For visual representation, refer to the figure below.
Properties
Material: Set the material for the tendon.
Post-tension Type [Bonded/Unbonded]: Specify the post-tension type, Bonded or Unbonded.
Exposure [Internal/External]: Set the type of exposure of tendon, Internal or External.
Anchor Set Length: Anchor set length is user defined parameter.
Wobble Friction Coefficient: Enter the wobble friction coefficient.
Curvature Friction Coefficient (1/rad): Curvature friction coefficient μ (per radian) used in AASHTO friction-loss calculation. Typical values 0.15–0.25 for strand in galvanized metal duct; 0.05 for unbonded tendons.
Jacking
# of Strands: Number of strands in the tendon. Used with the strand section to compute total area and capacity.
Strand Type: Strand definition for the tendon (area, Fpu, Fpy, Es). The strand type can be picked from items defined under Properties.
Jacking Method: Jacking type [Start/End/Start then End/End then Start]: Specifies the jacking sequence applied to the column tendon. 'Start' and 'End' refer to the top and bottom of the column tendon respectively. Use 'Start then End' or 'End then Start' for two-stage jacking.
Jacking Force From Start: applied jacking force to the start of tendon.: Jacking force applied at the start (top) of the column tendon. Must be specified unless Jacking Method is 'End'. Unit family Force.
Jacking Force From End: applied jacking force to the start of tendon.: Jacking force applied at the end (bottom) of the column tendon. Must be specified unless Jacking Method is 'Start'. Unit family Force.
FEA Settings
In OpenBrIM, short-term losses are calculated automatically. The effect of these losses can be observed from clicking the three-dot menu of any cell and selecting “Prestressing Details…”. (Note: FEM generation needs to be activated).
Load Dist. Elem. Type [FENodes/FELines]: This input affects the type of finite elements loads are distributed. FELines are used for beam elements.
Percent Loss(%): Set the percent loss for the long-term losses. This is an optional input. Users can leave this input as 0 and let OpenBrIM calculate the long-term losses using the CEB-FIB 1990 curve by running the time-dependent analysis. Alternatively, users can set an approximate value for the Percent Loss (%) to account for long-term losses, which will reduce the Jacking Force values of the tendon.
3D Settings
Show Tendon(Detailing) [No/Yes]: Toggles visibility of the tendon geometry in the 3D detailing view. Set to Yes to display the tendon path, No to hide it.
There are two methods for calculating tendon losses in OpenBrIM. The first method, the approximate method, involves defining the Percent Loss (%) of the tendon objects on the FEA tab, as outlined above. The second method, the detailed method, is as follows:
Defining Time-Dependent Material Properties for tendon materials: Refer to Properties-Materials for parameters such as:
Steel Relaxation Effect
PT Losses from Structure
Defining CEB-FIB 1990 Parameters of the materials: Refer to Properties-Materials for defining parameters such as:
Steel Relaxation Class
Making Construction Stage Definitions: Refer to Construction-Construction Stages for making stage definitions by:
Construction Day
Code
Steel Relaxation Effect
PT Losses from Structure
Defining the Associated Result Extraction Cases: refer to screenshot below for example case definitions.
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