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Create and modify slab patches

Tekla Structural Designer
Modified: 7 Feb 2025
2025
Tekla Structural Designer

Create and modify slab patches

You can apply rectangular patches of reinforcement to individual slab items to act in addition to the background reinforcement. After selecting the patch type, you can place patches in the model by clicking or boxing around elements in 2D or 3D views.

Create column patches

  1. On the Design toolbar, click the arrow on the left side of the Patch list.
  2. In the list, select Patch Column.
  3. In the Properties window, adjust the patch properties according to your needs.
    1. To specify the patch size, type values in the Lx and Ly fields.
    2. To specify the layer of the patch, select the desired option in Surface.
    3. To have the reinforcement automatically designed, select the Autodesign option.
    Note:

    Only select the Consider patch surface moments only option if you do not want Tekla Structural Designer to consider the opposite surface.

    One example where you would need the option is when the check of slab reinforcement in the opposite surface fails, but another patch exists in the same location at that face. When the second patch is designed, additional reinforcement is provided at the surface, so the surface check is not required for the original patch.

  4. According to your needs, do one of the following:
    To Do this
    Place a patch over a specific column

    • Click a column node within the slab.

      Tekla Structural Designer creates a patch to the selected column.

    To Do this
    Place multiple patches

    1. Move the mouse pointer to one corner of an imaginary box that will encompass the columns to which you want to create patches.

    2. Hold down the left mouse button.

    3. Drag the mouse pointer to the opposite corner of the box.

    4. Release the mouse button.

      Tekla Structural Designer creates patches to all columns entirely within the box.

Note:

If a punching check is applied in the same location as the column patch, the additional reinforcement specified in the patch is only considered in the punching check in the case where the punching check is wholly within the column patch.

Create beam patches

  1. On the Design toolbar, click the arrow on the left side of the Patch list.
  2. In the list, select Patch Beam.
  3. In the Properties window, define the required patch width (perpendicular to the beam span) and the center slab width.

    Tekla Structural Designer recalculates the two end strips accordingly. The strips cannot be modified.

    Note:

    Only select the Consider patch surface moments only option if you do not want Tekla Structural Designer to consider the opposite surface.

    One example where you would need the option is when the check of slab reinforcement in the opposite surface fails, but another patch exists in the same location at that face. When the second patch is designed, additional reinforcement is provided at the surface, so the surface check is not required for the original patch.

  4. According to your needs, do one of the following:
    To Do this
    Place a patch over a specific beam span

    • Click the required beam span.

      Tekla Structural Designer creates a patch centered on and orientated to the beam center line.

    To Do this
    Place multiple patches

    1. Move the mouse pointer to one corner of an imaginary box that will encompass the beams to which you want to create patches.

    2. Hold down the left mouse button.

    3. Drag the mouse pointer to the opposite corner of the box.

    4. Release the mouse button.

      Tekla Structural Designer creates patches to all beams entirely within the box.

Create wall patches

  1. On the Design toolbar, click the arrow on the left side of the Patch list.
  2. In the list, select Patch Wall.
  3. In the Properties window, adjust the patch properties according to your needs.
    1. To specify the layer of the patch, select the desired option in Surface.
    2. To have the reinforcement automatically designed, select the Autodesign option.
    3. Define the required patch width perpendicular to the wall.
    Note:

    Only select the Consider patch surface moments only option if you do not want Tekla Structural Designer to consider the opposite surface.

    One example where you would need the option is when the check of slab reinforcement in the opposite surface fails, but another patch exists in the same location at that face. When the second patch is designed, additional reinforcement is provided at the surface, so the surface check is not required for the original patch.

  4. According to your needs, do one of the following:
    To Do this
    Create a patch along a specific wall

    1. In the Properties window, set Create Mode to Single Patch Along Wall.

    2. Click the required wall.

      Tekla Structural Designer creates a patch, centered on and orientated to the wall center line.

    To Do this
    Place an internal patch and two end patches along a specific wall

    1. In the Properties window, set Create Mode to Internal With End Patches.

    2. Click the required wall.

      Tekla Structural Designer creates an internal patch and two end patches, centered and orientated to the wall center line.

    To Do this
    Place an end patch at one end of a specific wall:

    1. In the Properties window, set Create Mode to End Patch at Wall End.

    2. Click near the required end of the wall.

      Tekla Structural Designer creates a patch at the end of the wall that is closest to the point that you clicked.

    To Do this
    Place an internal patch part way along a specific wall

    1. In the Properties window, set Create Mode to Internal Patch.

    2. Click to define the start point of the patch along the required wall.

    3. Click to define the end point of the patch along the required wall.

      Tekla Structural Designer creates a patch between the selected points.

    To Do this
    Create patches along multiple walls

    1. In the Properties window, set Create Mode to Single Patch Along Wall or Internal With End Patches.

    2. Move the mouse pointer to one corner of an imaginary box that will encompass the walls to which you want to create patches.

    3. Hold down the left mouse button.

    4. Drag the mouse pointer to the opposite corner of the box.

    5. Release the mouse button.

      Tekla Structural Designer creates patches to all walls entirely within the box.

Create panel patches

Note:

Panel patches can be applied in slab and mats where other patch types are not applicable, however they should not be used in situations where a different patch type would be more appropriate. For example, while you are not prevented from placing a panel patch in a slab or mat at a column location, the panel patch reinforcement would not be considered in any punching checks applied to the column. (If a column patch had been used, the patch reinforcement would be considered).

  1. On the Design toolbar, click the arrow on the left side of the Patch list.
  2. In the list, select Patch Panel.
  3. In the Properties window, adjust the patch properties according to your needs.
    1. To specify the patch size, type values in the Lx and Ly fields.
    2. To specify the layer of the patch, select the desired option in Surface.
    3. To have the reinforcement automatically designed, select the Autodesign option.
    Note:

    Only select the Consider patch surface moments only option if you do not want Tekla Structural Designer to consider the opposite surface.

    One example where you would need the option is when the check of slab reinforcement in the opposite surface fails, but another patch exists in the same location at that face. When the second patch is designed, additional reinforcement is provided at the surface, so the surface check is not required for the original patch.

  4. According to your needs, do one of the following:
    To Do this
    Place the patch at the centroid of a specific panel

    1. In the Properties window, ensure that the Create Patch at Centroid option is selected.

    2. Click anywhere within the required panel.

      Tekla Structural Designer creates a patch at the panel centroid.

    To Do this
    Place the patch elsewhere within a specific panel

    1. In the Properties window, ensure that the Create Patch at Centroid option is cleared.

    2. Still in the Properties window, do one of the following:

      • To define the patch by its corners, select the Define corner points option.

      • To define the patch by its center, clear the Define corner points option.

    3. In the panel, click the points that define the patch.

      Tekla Structural Designer creates a patch at the selected position.

    To Do this
    Create multiple centroid patches

    1. In the Properties window, ensure that the Create Patch at Centroid option is selected.

    2. Move the mouse pointer to one corner of an imaginary box that will encompass the panels to which you want to create patches.

    3. Hold down the left mouse button.

    4. Drag the mouse pointer to the opposite corner of the box.

    5. Release the mouse button.

      Tekla Structural Designer creates patches to the centroids of all panels entirely within the box.

Resize patches

  1. Hover the mouse pointer over the patch that you want to resize.

    The Select Entity tooltip appears.

  2. In the Select Entity tooltip, use the arrow keys to navigate to the patch name and press Enter.
  3. Hover the mouse pointer over the patch edge or corner that you want to adjust.

    The Select Entity tooltip appears.

  4. In the Select Entity tooltip, use the arrow keys to navigate to the edge or corner node and press Enter.
  5. Hold down the left mouse button and drag to move the edge or corner.

Patch properties

Select one or more patches and then use the Properties window to view and modify their properties.

General
Name The automatically generated name for the patch.
User Name Can be used to override the automatically generated name if required.
Type
  • Column
  • Beam
  • Wall
Lx Specifies the size of the patch in the X direction.
Ly Specifies the size of the patch in the Y direction.
Associated Slab Panel Where a patch sits over more than one panel then an automatic choice is made, but you are able to override this if required by selecting one of the alternative panels from a drop-down list.
Align to Panel Reinforcement When this checkbox is selected, the calculated strip reinforcement is aligned with the background reinforcement in the Associated Slab Panel.
Note: This option cannot be activated unless all slab items below the patch are aligned within a tolerance of 10 degrees.
Local X Angle The angle of the X axis reinforcement is only editable if Align to Panel Reinforcement is cleared.
Surface
Specifies the reinforcement to be associated with and designed by the patch:
  • Top or Bottom (cannot be both).
Autodesign

This setting applies to all strips in both directions, but reinforcement in either direction can still be set to none - see below.

  • Cleared - the specified reinforcement will be checked during the design process.
  • Checked - reinforcement will be designed during the design process.
Select bars starting from

This option controls the starting point for auto-design procedures.

  • Minima (default) - removes the current arrangement and begins with the minimum allowed bar size.
  • Current - the auto design commences from the current bar arrangement.
Consider Strips

This setting controls which strips are to be designed by the patch.

  • X
  • Y
  • X and Y
Consider patch surface moments only Off (default)
  • patch reinforcement is designed in the surface of the slab at which the patch has been specified AND the slab reinforcement is also checked in the opposite surface.
On
  • patch reinforcement is designed in the surface of the slab at which the patch has been specified, but the slab reinforcement in the opposite surface is NOT checked.
    Note: The only situation when you might need to activate this option is if the check of slab reinforcement in the opposite surface fails but another patch exists in the same location at that face.(When the other patch is designed additional reinforcement will be provided at that surface, so this check is not required for the original patch).
Strips in X, Strips in Y

Center, Left and Right Strip
Width

The left and right strip widths can be specified independently: the center strip width is recalculated accordingly and cannot be edited.

(By default the center strip covers half the panel, so that the left and right strips each cover a quarter of the panel.)
Design Force

• Average (of all the FE nodal values within the strip).

• Maximum (of all the FE nodal values within the strip).
Reinforcement
Combine with Panel Reinforcement When this checkbox is selected, the calculated strip reinforcement takes into account any existing panel reinforcement in the Associated Slab Panel that is in the same alignment as the strip.
Cover as Panel When this checkbox is selected, the cover is set to be the same as that in the Associated Slab Panel.
Outer Bar Direction as Panel

When this checkbox is selected, the outer bar direction is set to be the same as that in the Associated Slab Panel.

When cleared, the outer bar direction can be set in X or Y.
Reinforcement
Combine with Panel Reinforcement When this checkbox is selected, the calculated strip reinforcement takes into account any existing panel reinforcement in the Associated Slab Panel that is in the same alignment as the strip.
Cover as Panel When this checkbox is selected, the cover is set to be the same as that in the Associated Slab Panel.
Outer Bar Direction as Panel

When this checkbox is selected, the outer bar direction is set to be the same as that in the Associated Slab Panel.

When cleared, the outer bar direction can be set in X or Y.
Reinforcement

This setting is used to specify whether bars or mesh are to be used in each direction.

• Mesh

• Bars XY

• Bars X

• Bars Y

• None

(If Mesh is selected an extra setting then allows you to specify if main bars are in X or Y.)
Reinforcement in X, Reinforcement in Y, or Mesh
Bar Size, spacing, Mesh type etc. The actual reinforcement provided in each of the strips is indicated here.
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