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Open the Sectional strand pattern manager.
Click button [New].
Select the cross-section for which a new strand pattern should be defined.
Close the Cross-section database manager.
Select the bore hole pattern for which a new sectional strand pattern should be defined.
Close the Bore hole pattern manager.
A small positioning dialogue is opened on the screen.
Position the bore hole pattern in the cross-section (see the note below).
The editing dialogue for a sectional strand pattern opens on the screen.
Define the new sectional strand pattern.
Confirm with [OK].
Note: This positioning of the bore hole pattern on the cross-section may become important later when you decide to change the height of the cross-section. The position of strands is related to the reference point and is not affected by the change of the dimension. You may choose the reference point which most suits your needs.
The dialogue for the definition or editing of a sectional strand pattern consists of the following parts:
graphical window,
info-table,
legend,
strand properties,
view parameters button,
debonding length button,
control buttons.
The graphical window displays the selected cross-section and the defined pattern of holes. It supports standard features of SCIA Engineer graphical windows:
[Ctrl] + [Shift] + right-click and drag to zoom in and out the drawing,
[Shift] + right-click and drag to move the drawing.
This table is located in the top left corner of the dialogue.
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Name |
Specifies the name of the pattern. |
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Cross-section name |
(informative) Informs about the cross-section used in the sectional pattern. |
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Bore hole |
(informative) Informs about the bore hole used in the sectional pattern. |
The legend has two roles:
(informative) it explains the symbols used in the graphical window (each type of strand uses a special graphical mark or colour),
(active) it is used for the input of individual strands into the bore holes.
In the Legend select the required strand material and diameter.
In the graphical window click the holes where you want to have a strand.
If you need to combine more materials/diameters, simply repeat steps 1 and 2.
In the Legend select item No Strand.
In the graphical window click the strand you want to remove.
In the Legend select the item Debonded or Fixed.
In the graphical window click the appropriate strand(s).
Alternatively, you may define these two properties in the property window of the required strand (see below).
Whenever a defined strand is selected in the graphical window, its properties are shown in the Properties window.
Name
Specifies the name of the strand.
ID
Specifies the ID of the strand.
Group
(informative) The number of strand group.
Material
Selects the material and diameter.
Position in hole
It specifies the position of the tendon withing the hole (centre, top, bottom, left, right).
Fixed
Specifies if the strand is fixed. The fixed strand has fixed position in the section along the whole length of the 1D member. It is straight.
Debonding length
Defines whether the strand is debonded at its end and if so, over which distance.
Also the debonded strand has fixed position in the section along the whole length of the 1D member. It is straight.
Stressing sequence
Defines the sequence in which the strands are stressed.
Type o stressing
See chapter Properties of pre-tensioned tendons.
Stress during correcting
Stress at stressed end of tendon; the amount of relaxation can be decreased by keeping the stress constant (so called correction of relaxation)
Duration of keeping stress
Duration of keeping constant stress during correction of relaxation.
Initial stress
Initial stress at stressed end of tendon (before seating)
Anchorage set
Defines the slip at the stressed end of the strand.
Determine transmission length
This item says how the transmission length will be determined. It may be calculated by the program or input directly by the user.
Transmission length
The length of development of bond between the concrete and pre-tensioned tendon.
Note: Read paragraph Transmission and anchorage length at the end of the topic.
Distance between sections for output
Specifies the distance for output.
Hook
This item defines the position of the hook.
Position Y, Z
(informative) Shows the position of the strand.
Note: In the property window you may use selection-by-property. Select one strand, in the property window select the property you are interested in, click the "funnel" icon in the top right corner of the property window and the program selects all the strands that have the same property. The selected strands are highlighted in the graphical window. This feature can be used for both active and informative properties.
Note: It is possible to make a multiple selection of strands in the graphical window. Press and hold key [Ctrl] and click the left mouse button. When the multi-selection has been made, you can change a required property to all the selected items at once.
This button opens a dialogue with view parameters. Their meaning is more or less self-explanatory.
A set of various debonding lengths can be defined through this button. One debonding length can be then assigned to a strand in the property window.
For all codes except Eurocode, the transmission length is the only value (related to the development of bond) appearing in the output document..
For EC-EN, in addition to the transmission length also term anchorage length is defined. The anchorage length is calculated automatically by the program.
Transmission length l_pt is the length over which the initial prestressing force is transferred into service Concrete Advanced.
Anchorage length l_bpd is the length over which the limit prestressing force is transferred into service Concrete Advanced.
The ultimate limit state checks include Check of response and Check of capacity. These two checks use the anchorage length to verify the length for transfer of the prestressing.
The serviceability limit state checks include Crack control and Allowable stress in service Concrete Advanced. These two checks use the transmission length to verify the length for transfer of the prestressing.
This group includes Allowable principle stress and Check of mechanical resistance of hollow core panels. These two checks use the transmission length to verify the length for transfer of the prestressing.