Post-tensioned cable (PTC)
Post-tensioned cable property | Description |
---|---|
Icon | ![]() |
Modules where available | ![]() ![]() |
Function | It is a structural component, modelled by equivalent load system. |
Axis position | Arbitrary (horizontal, vertical and skew) |
Geometry | Straight |
Shape | Wavy with Base points and Inflection places |
Result |
|
Manufacturing | the Manufacture drawing can be set with proper x’ and z’ shift |
Default Short Command | BPTC |
Table: Post-tensioned cable properties
Definition steps
- Start
Post-tensioned cable for bars/Post-tensioned cable for shells command from
tabmenu and pick the parent object (a bar or a shell), then define the line of the PTC.
The two Tool window work in slightly different ways: for shells, the user can define more cables by using Line by selection option, but for bars only one cable can be defined.It is strongly recommended to use Axes: all aid functions (Macros, Shape wizard, Layout wizard) highly rely on them. It could greatly speed up the definition process. - Click
Default settings and set the properties of the PTC
.- Identifier (General)
The program automatically generates it, but you can define custom value. Identifier (ID and Position) number can be displayed in model view (Display settings). - Strands (General)
User can set the type from the strand library and the number of the strands by typing. - Jacking (General)
User can select the Jacking side in the drop-down menu next to Jacking side. Jacking side options: Start, End, Start then End, End then Start. The last two are Both-sided jacking with same stress, but it was necessary to distinct, because the effect of draw-in could result in different stress functions using shorter cables.
Jacking stress is calculated as 0.8 * fpk by default after the Strand type selection. - Short term losses (General)
- friction: It is estimated by EN 1992-1-1 5.10.5.2 (1) (formula 5.45) using the Wobble (k) and Curvature coefficients (µ):
- anchorage set slip
- elastic shortening
- Long term losses (General)
- shrinkage of structure
- creep of structure
- relaxation of post-tensioned cable
- Shape
There are settings related to the geometry of the cable (Display settings) here. The Shape table can contain Base points and Inflection places: these determine whether linear or parabolic shape is applied.
The Top and Bottom values mean the distance between the axis of the cable and the edge of the element.
Using Shape wizard (Shape wizard… button) parabolic shapes can be easily created. This tool highly relies on previously defined axes. - Results
There are several results -listed in the order of calculation - which can be chosen from Result tab/Result drop-down menu. - Manufacturing
On this tab the Manufacture drawing can be set with proper x’ and z’ shift.
- Identifier (General)
Optional steps:
- Modify the PTC properties with the
Properties tool of the Post-tensioned cable bar/shell tool palette.
- Set the display settings of PTC elements at Settings > All > Display > Post-tensioned cables.
- The PTCs are stored on “Post-tensioned cable” Object layers. At layer settings, the default color and pen width can be set for all PTC elements. The color and pen width settings by selected PTC elements can be modified by Edit > Properties > Change appearance.
Layout wizard
It is a tool to create a set of PTCs in a specific layout. It can be launched from Structure/Shell component/Post-tensioned cable/Layout wizard.
The Layout wizard searches for the closest solution to the Unequal loading settings from the PTC layout variations which fulfilled the following conditions:
- difference between the sum of the PTC’s forces acting in local z+ direction and the product of Considered load and Balance ratio is less than the Maximal deviation
- geometrical requirements
The Layout calculation process shows the currently calculated layout parameters and a few indicator values. After the calculation it shows the parameters of the best found solution.
The function uses Axes to divide the selected structural element to stripes (Mid span and Column span) assuming columns in the axes cross points.
The algorythm can handle the holes of the plate regions.
![]() | At least two Axes crossing the plate are needed to use this tool. |
![]() | Checking Shape wizard using height [mm] instead of physical model option can highly reduce the runtime if the selected plate’s thickness is constant. |