Tendon Profile

 

 

 

Define a tendon profile along the length of elements. Create the tendon profile relative to its own coordinate system, which will then be inserted relative to the elements.

Note 1
Tendon placement can be simplified by copying, rotating and sloping tendon profiles.

Note 2
From V 6.3.0, tendon properties can be changed at the Tendon Profile location in Works Tree.

 

 

 

From the Main Menu select Load > Prestress Loads > Tendon Profile.

Select Static Loads > Prestress Loads > Tendon Profile in the Menu tab of the Tree Menu.

 

 

Tendon Profile dialog box

Note
If a Tendon Profile is selected from the Tendon Profile List, the tendon placement is displayed on the screen.

Click in the Tendon Profile dialog box to enter new tendon placement.

Click to change and to eliminate a previously defined profile.

: Tendon properties assigned to a number of Tendon Profiles can be changed at the same time.

Revision of  Civil 2010

: Tendon Profile can be exported to DXF as a 2D format (x-z Plane and x-y Plane).

Note
If there are a number of Profiles, which are required to have Tendon Properties changed, this functionality allows us to change them simultaneously, rather than changing them one by one in each profile.

Change Tendon Property dialog box

Click on the button to Copy or Move the inputted Tendon Profile

Copy/Move Tendon Profile Dialog box

Mode

Copy: Copy the selected Tendon Profile

Move: Move the selected Tendon Profile

Translation

Select one of the following options to Copy/Move the selected Tendon Profile

Element Increment: Copy/Move the selected Tendon Profile as per the inputted increment of element number. To Copy/Move the tendon profile defined with this option, at 1, 3, 5, 7 (G1), the following conditions should be satisfied.

 

· The increment of each corresponding element should be identical

For example, Tendon Profile entered in element 1, 3, 5, 7 (G1) can be Copied/Moved to element 51, 53, 55, 57 (G2) because the increment is identical. On the other hand, the Tendon Profile cannot be Copied/Moved to 11, 12, 13, 14 (G3) because the increment is different for each element.

 

· The number of elements to Copy/Move should be the same

For example, the Tendon Profile entered in element 1, 3, 5, 7 (G1) can be Copied/Moved to G4 which has the same number of elements. On the other hand, Tendon Profile cannot be Copied/Moved to G5 since the number of elements is different.

As displayed the figure below, the length of each element does not matter while performing the Copy/Move commands.

 

Element Increment Option

Note

1. Element Increment option can be selected only when the Tendon Profile is defined.

2. Element Increment option is a change of element that is included in Assigned Elements and Insertion Point.

 

 

Equal Distance

 

Enter the absolute distance to Copy/Move the Tendon profile to a particular location. While using this option, the following conditions should be satisfied.

 

 

At the distance inputted to Copy/Move the Tendon Profile from the initial Insertion Point of the original element, a node of the element where the Tendon Profile is to be Copied/Moved must exist. This node will define the new Insertion Point. If this node does not exist, then an error message will be displayed.

 

 

 

If there is more than one element attached to the initial element, then the Tendon Profile will be assigned to the attached element that is most linear.

 

 

If Straight/Curve type Tendon Profile is to be Copied/Moved, then the original length and number of elements should be equal to the length and number of elements at the new location.

Current Assigned Element: It is used to copy Tendon Profile within an element. This option is useful when generating Web Tendons which exist at different locations of the same element. With this option off, tendons only can be copied if another element exists at the distance specified. However, with this option on, it is possible to copy Tendon Profile irrespective of element existence.

New Assigned Element: Input new Assigned Elements and Insertion Point to Copy/Move a Tendon Profile to those elements.

Auto-Adjustment of Tendon Length

If a Tendon Profile is Copied/Moved to an element whose total length is different from the total length of the original element, then checking this option will automatically adjust the tendon length based on the ratio of the original element length to the length of the element where the Tendon Profile is copied.

Move

Move the previously defined tendon layout.

Tendon Profile Definition dialog box

 

Tendon Name

Note 1
Name assigned within 20 alphanumeric characters

Note 2
Bridge Wizard of midas Civil automatically assigns the following tendon names:

l ILM Bridge Model Wizard

Top n-m: Top tendon

BOT n-m: Bottom tendon

where,

n: Sequential tendon numbers starting from the right edge to the center line of a PSC box cross section looking in the x-axis direction. The tendons are numbered symmetrically in the left half section.

Note
The x-axes of the elements are oriented from the start (left) end to the finish (right) end of the bridge. However, the launching direction is from the right end to the left end of the bridge.

m: Sequential numbers starting from the left end of the bridge to    represent the groups of tendons in cycles.

Web n-m: Web tendons defined as Type 1

where n: Sequential tendon numbers starting from the right web of a PSC box cross section looking in the x-axis direction

m: Sequential numbers starting from the left end of the bridge

Web n: Web tendons defined as Type 2

where n: Sequential tendon numbers starting from the lower right web of a PSC box cross section looking in the x-axis

 

l FCM Bridge Wizard

Top n-m: Top tendons at the n th pier stressed at the m th sequence

FSMBot n-m: Bottom tendons stressed at the m th sequence within the FSM zone.

where n represents 1: FSM zone at the start (left) end

2: FSM zone at the finish (right) end

Bot n-m: Bottom tendons in the n th span stressed at the m th sequence

where n: Sequential span numbers starting from the left excluding the two end exterior spans

l MSS/FSM Bridge Wizard

CSnam-l: Tendons placed in the element activated at the construction stage CSn

where a, b: Tendons placed at the exterior face (a) and interior face (b) of the web

m: Sequential layer number from the bottom of the PSC section

l, r: Tendons placed in left (l) and right (r) webs of the PSC section

 

Group

Define Tendon Groups. Once Tendon Groups are defined, coordinates, stresses and prestress losses of tendons can be checked by Tendon Groups. Click to the right to add new, modify or delete previously defined Tendon Groups. Tendon Groups can be assigned to the tendons having the same tendon property.

Tendon Property

Define the tendon properties. Click to the right to add new, modify or delete previously defined tendon properties.

Assigned Elements

Specify the element numbers to which the tendon will be assigned.

Use the Graphical Selection function of midas Civil to automatically specify the numbers by selecting the elements on the screen.

Input Type

The dimension of Tendon Profile is specified.

2-D
Tendon Profile is defined in 2-dimensional coordinates.

3-D
Tendon Profile is defined in 3-dimensional coordinates.

Curve Type

Specify the type of curvature for tendon placement.

Spline
Calculate the minimum polynomial curvature connecting the points defining the tendon profile and auto-place the tendons

Round
Place the tendons following the circle, which forms tangents to the straight lines connecting the points defining the tendon profile.

Straight Length of Tendon

Specify the straight portions of the tendon at both ends.

Begin: at the beginning of the tendon

End: at the end of the tendon

Typical Tendon

This is a function for defining a lumped representative tendon. If this option is checked on and the number of tendons is inputted, the generated tendon profile is multiplied by the inputted number of tendons when analysis is performed. For simple analysis, such as the schematic design of a bridge, inputting 3 dimensional tendon profiles is time consuming. Therefore, using the function of lumped representative tendon, which defines only one tendon profile for analysis, the time required for generating the model and performing analysis can be reduced.

After analysis is performed, the tendon results, like tendon loss, elongation etc. are displayed as one tendon.

No. of Tendon: Number of lumped representative tendons

Transfer Length

Enter a Transfer Length. In both pre tensioned and post-tensioned beams, compressive stress due to tendon prestressing forces is not fully distributed to the top and bottom fibers of the member near the end anchorage zones or beam ends over a Transfer Length.

The Transfer Length can be either input by the user or obtained by automatic calculation. For the automatic calculation by formula, two methods are available depending on Tendon Property (Post-tension or Pre-tension).

User Defined Length: Enter a Transfer Length manually.

Begin: Beginning portion of the Transfer Length

End: End portion of the Transfer Length

Auto Calc (0.5x(H+Bf/n): For Post-tensioning, the transfer length is auto-calculated as below.

L=0.5x(H+Bf/n)

where,  H: Section depth, Bf: Flange width, n: Number of webs (2 for 1Cell)

Auto Calc (65xStrand Diameter): For Pre-tensioning, the transfer length is auto-calculated as below.

L=65xStrand Diameter

Profile

Place the tendon profile by defining the coordinates of the tendon. The tendon coordinate system (TCS) used here is temporary, and its origin is the starting point of the tendon, which will be related to the elements by the profile insertion point. As many coordinates as required to define the profile may be specified, but at least two (start and end) points are required. The x-axis of TCS is parallel with a Global axis in the length direction, and the z-axis of TCS coincides with the Global Z-axis. See Tendon Shape below for further details.

Reference Axis

Straight: the x-direction (the reference line from which tendon coordinates are defined) of TCS for tendon placement is considered as a straight line.

Curve: the x-direction (the reference line from which tendon coordinates are defined) of TCS for tendon placement is considered as a curved line.

Element: Tendon location is converted into Element Coordinate System and applied.

Note
If Element is selected in Tendon Shape, Tendon Profile moves with Element's movement.
 

Note
If Tendon Profile is defined by Element Type, the tendon length is calculated based on the element length and the elongation may not be accurate in case of greatly curved tendons. Therefore, it is recommended to use Straight or Curve Type for defining greatly curved tendon profiles.

If Spline is selected in Curve Type

x, y, z: tendon coordinates in TCS

fix: check in the box to specify the tangent to the tendon curvature at the point in question.

Ry: if fix is checked, the angle of the tangent line relative to the x-axis in the TCS x-z Plane

Rz: if fix is checked, the angle of the tangent line relative to the x-axis in the TCS x-y Plane

Note
The tendon profile is created following the geometry specifications and maintaining the least change of curvatures.

 

If Round is selected in Curve Type

When Round of Curve Type is selected, the tendon profile is created using straight lines and arcs.

R: Enter the radius of an arc at the corresponding point.

Add

Right: Generate a point to the right of the entered point.

Left: Generate a point to the left of the entered point.

A[deg]: Angle formed from the line connecting the entered point and the additionally created point to the x-axis. The upward direction is (+) and the downward direction is (-) with reference to the x-axis.

h: Distance from the entered point to the additionally created point in the y or z-direction. (Distance should be a positive value.)

r: Radius of an arc at the additionally created point

Note
When 2-D of Input Type and Round of Curve Type are used to create the Tendon Profile shown in the figure below, it can be simply created by using the coordinates (x1, y1), (x2, y2) and A1, A2, h1, h2, r1, r2. When the Tendon is to be placed to the right of the entered coordinates, select Right in the Add column. When it is to be placed to the left of the entered coordinates, select Left in the Add column.

Input Tendon Profile by using 2D Round

 

BOT: If BOT is checked on two points of a tendon profile, whose vertical distances from the bottom of the section (z distance) are equal, then the vertical distance from the bottom of the section to the tendon remains the same between the two points. However, if the two points where BOT is checked have different vertical distances from the bottom of the section, then the tendon is considered to be a straight line and its coordinates are linearly interpolated at intermediate points.

For the following cases, BOT cannot be checked

If Spline is selected: If the corresponding points are included in a straight line (inputted in Straight Length of Tendon) then BOT cannot be selected.

If Round is selected: If R is inputted on the corresponding point then BOT cannot be selected

.

 

Point of Sym.

First: The starting point of the current Tendon is assumed to be the axis of symmetry.

Last:  The end point of the current Tendon is assumed to be the axis of symmetry.

: Tendon Profile is created on the basis of the selected symmetry point (First or Last).

 

1. If Straight is selected in Reference Axis

Profile Insertion Point
The origin of the tendon coordinate system (start point of tendon) is identified and inserted into the actual location in the global coordinate system.

x Axis Direction
In case the Reference Axis is Straight, define the x-axis of TCS for tendon placement.

X: x-axis of TCS is parallel with GCS X-axis

Y: x-axis of TCS is parallel with GCS Y-axis

Vector: define the TCS x-direction by a Vector specified in the entry field below  

x Axis Rot. Angle
The tendon profile placed in the table is rotated about TCS x-axis by the Angle. This is usefully implemented when placing a tendon on an inclined (non-vertical) web

Note

x-axis Rot. Angle must be entered between -85 and +85 degrees.

Projection
The tendon profile placed in the table is projected on the plane, which is rotated about TCS x-axis by the Angle.

Grad. Rot. Angle
The tendon placement is rotated about the GCS Y or X-axis. This is a useful feature when attempting to place the tendon in a section, which is tilted (rotated) about its local x-axis.

Note
Tendons can be placed only in beam elements. The assigned beam elements do not necessarily have to be interconnected. We can check the Tendon Profile in the Misc. tab of Display by checking in the appropriate box. External tendons are assumed to retain the straight line placing profile.

 

2. If Curve is selected in Reference Axis

Profile Insertion Point
The origin of the tendon coordinate system (start point of tendon) is identified and inserted into the actual location in the global coordinate system.

Radius Center (X, Y)
In case the reference axis is a Curve, enter the coordinates of the center of the circle in GCS.

Offset: place the tendon at the projected location in the radial direction

Note
In the case of a Curved Tendon Shape, the tendon is placed along the circumference of the circle defined by the radius formed by the start point of the tendon (origin of TCS) and the center of the circle. The Offset increases or decreases the radius by the specified magnitude while maintaining the center of the circle. Again the tendon is placed along the changed circumference. When several tendons are placed side by side, use the Copy function to copy the previously entered tendon and relocate the copied tendon by Offset.

Direction

CW: define the curve clockwise

CCW: define the curve counter-clockwise

x Axis Rot. Angle
The tendon profile placed in the table is rotated about TCS x-axis by the Angle. This is usefully implemented when placing a tendon on an inclined (non-vertical) web.

Note

x Axis Rot. Angle must be entered between -85 and +85 degrees.  

Projection
The tendon profile placed in the table is projected on the plane, which is rotated about TCS x-axis by the Angle.

Grad. Rot. Angle
The tendon placement is rotated about the GCS Y or X-axis. This is a useful feature when attempting to place the tendon in a section, which is tilted (rotated) about its local x-axis.

Note
Tendons can be placed only in beam elements. The assigned beam elements do not necessarily have to be interconnected. We can check the Tendon Profile in the Misc. tab of Display by checking in the appropriate box. External tendons are assumed to retain the straight line placing profile.

 

 

3. If Element is selected in Reference Axis

Profile Insertion Point
Specify the corresponding element number at which the tendon starts.

End-I of Elem.: I-end of the specified Element is referenced as the insertion point.

End-J of Elem.: J-end of the specified Element is referenced as the insertion point.

x Axis Direction
In case the Reference Axis is an Element, define the x-axis of TCS (Tendon Coordinate System) for tendon placement.

I->J of Elem.: The x-axis in TCS is defined in the direction from the I-end to J-end of the element.

J->I of Elem.: The x-axis in TCS is defined in the direction from the J-end to I-end of the element.

x Axis Rot. Angle
The tendon profile placed in the table is rotated about TCS x-axis by the Angle. This is usefully implemented when placing a tendon on an inclined (non-vertical) web.

Note

x Axis Rot. Angle must be entered between -85 and +85 degrees.

Projection
The tendon profile placed in the table is projected on the plane, which is rotated about TCS x-axis by the Angle. The projection direction is in the TCS y-axis prior to rotation.

Offset: Tendon Offset is defined in the Element Coordinate System (ECS).

y: Distance by which the tendon profile is moved in the ECS y-axis direction

z: Distance by which the tendon profile is moved in the ECS z-axis direction