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Create a concrete lofted slab

Last updated November 7, 2019 by Tekla User Assistance tekla.documentation@trimble.com

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Create a concrete lofted slab

Create a concrete lofted slab

With lofted slabs you can create curved and double-curved slabs or walls, for example.

Prerequisites and examples of lofted slabs

Before you can create lofted slabs, you need to have construction objects in your model. Tekla Structures creates the shape of the lofted part according to the geometry of the used construction objects.

You can connect the following construction objects as a lofted slabplate that represents a concrete structure

In Tekla Structures, a slab is created by picking three or more points.

Slab may be part of a floor, for example.


  • construction lineconstruction object that represents a line between two points

    to construction line

    For example:

  • construction line to construction arc

    For example:

  • construction arc to construction arc

    For example:

  • construction circleconstruction object that represents a circle

    to construction circle

    For example:

Note that rebar sets do not work with lofted parts.

Create a lofted slab

  1. Create the needed construction objects in the model. The shape of the lofted slab is based on the construction objectmodeling aid that represents a point, line, circle, or plane and that helps in placing other objects


    You need to have

  2. On the Concrete tab, click Slab Create lofted slab .
  3. On the toolbar that appears, click a button to specify whether to create the lofted slab by using two construction objects, or by using a construction object and a point.
    • If you selected Using two construction objects :

      1. Select the first construction object: line, arc, or circle.

        For example, if you are using two construction circles to create a lofted slab:

      2. Select the second construction object:

        Tekla Structures creates the lofted slab between the selected construction objects, using the Lofted slab properties in the property panecontrol element in Tekla Structures user interface in the form of a side pane window

        The property pane can be used to show and modify the properties of model objects.


    • If you selected Using one construction object and a point :

      1. Select the first construction object: line, arc or circle.

        For example:

        Tekla Structures shows a preview of the part geometry. Use the preview to set the direction and height of the lofted slab.

      2. Pick a point.

        Tekla Structures creates the lofted slab based on the preview.

Alternatively, you can start the Lofted slab command in the property pane.

  1. Ensure that you have nothing selected in the model.

  2. In the property pane, click the Object type list button and select Lofted slab from the list.

    Tekla Structures starts the command and shows the properties in the property pane.

Modify the shape of a lofted slab

Use direct modificationfunction that activates the mode where the model objects can be modified by using handles

Direct modification enables additional handles and modification options.

dimension handles and dimension values to modify the lofted slab shape.

  • Modify, for example, the height and radius of the lofted slab.

  • For lines and arcs: drag the arc symbolat the midpoint of a line or an arc to modify the lofted slab shape.

Split a lofted slab

Note that you cannot split closed cylindrical or conical lofted slabs.

  1. On the Edit tab, click Split.
  2. Select the lofted slab you want to split.
  3. Pick a point for the dividing line.

    Tekla Structures splits the lofted slab.

    For example:

Swap the end handle points to correct the geometry of a lofted slab

In some cases when you try to create a lofted slab by using construction lines, arcs, or circles, the geometry of the plate(1) part that represents a flat structure

(1) In some contexts, for example in analysis, the term plate object may be used to refer to plates.

(2) plate that represents a steel structure

(2) Plate is mainly used as a connection piece or as a floor plate.

would become self-intersecting. In these cases the slab is not created, and Tekla Structures displays the following status bar message: The resulting surface would be self intersecting.

You can try to resolve the situation and create the lofted slab by changing the modeling direction of the construction lines or arcs.

  1. Ensure that the Direct modification switch is not active.
  2. Select the construction line or the construction arc.
  3. On the contextual toolbarfloating toolbar that contains commands for modifying the most common object properties

    The user can customize the contextual toolbar.

    The term mini toolbar is used in Tekla Structures until version 21.1.

    , clickSwap ends.

    Tekla Structures changes the modeling direction and may help to you to create the lofted slab.

With construction circles you can try to resolve the situation by moving either of the circles.

Modify concrete lofted slab properties

  1. If the property pane is not open, double-click the lofted slab to open the Lofted slab properties.
  2. Change the properties as needed.
  3. Click Modify.

Lofted slab properties

Use the Lofted slab properties in the property pane to view and modify the properties of a concrete lofted slab. To open the properties, double-click the concrete lofted slab. The file name extension of a concrete lofted slab property filefile that contains properties or settings in the property pane or a dialog box

Property files are saved in the current model folder. The user can copy property files to the project or firm folders for future use.

User-defined attributes can be stored as a property file.

is *.lsl.

If you have customized the property pane layout, the list of properties may be different.





User-definable name of the lofted slab.

Tekla Structures uses part names in reports and in Document manager , and to identify parts of the same type.


Thickness of the slab.


Material of the lofted slab.


Type of finish.


Use to group lofted slabs.

For example, you can display parts of different classes in different colors.

Cast unit

Cast unit numbering

Part prefix and start number for the part position number.

Cast unit

Indicate whether the slab is precast or cast in place.

Pour phase

Pour phase of the cast-in-place parts. Use to separate pour objects from one another.

Face type

Face type

Select whether the top and bottom faces of the plate are flush with the plane.



Click the User-defined attributes button to open the user-defined attributes (UDAs) of the part. UDAs provide additional information about the part.

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by Kari Heinola

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