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Create mats

Tekla Structural Designer
Modified: 21 Mar 2025
2024
Tekla Structural Designer

Create mats

In Tekla Structural Designer, you can create various types of mat foundations, including minimum area mats, rectangular mats, strip mats, area mats, and mats within bays. Circular mats and mats with curved edges can be created by following the same instructions used for creating mats within bays.

For detailed information on creating mats, see the following instructions.

Create a minimum area or rectangular mat

  1. On the Foundations tab, click either Minimum Area or Rectangular.
  2. In the Properties window, adjust the mat properties according to your needs.
  3. Do one of the following:
    To Do this
    Create a mat in a 3D view

    1. Click anywhere on the first column or wall to be supported.

    2. Click to define the other necessary columns and walls.

    3. To create the mat, click the last column or wall again or press Enter.

    To Do this
    Create a mat in a 2D view

    1. To select multiple columns and walls, hold down the left mouse button and drag a box from right to left to encompass the columns/walls under which you want to create the mat.

    2. To add individual columns and walls, click each member individually.

    3. To create the mat, click one of the previously selected members or press Enter.

Create a strip mat

  1. Open a 2D view at the base level where you want to place the strip mat.
  2. On the Foundations tab, click Strip.
  3. In the Properties window, enter the width (measured from the strip center line to the edge).
  4. Adjust the other mat properties according to your needs.
  5. In the model, click the start point of the strip.
  6. Click to define the other necessary points.
  7. To create the strip, click the last point again or press Enter.

Create an area mat

Either click once again on the last point, or press <Enter> to create the mat.

  1. On the Foundations tab, click Area.
  2. In the Properties window, adjust the mat properties according to your needs.
  3. In the model, click a construction point at a corner of the area.
  4. Click to define the remaining corner points.
  5. To create the mat, click the last point again or press Enter.

Create a mat within bays

  1. On the Foundations tab, click Bays.
  2. In the Properties window, adjust the mat properties according to your needs.
  3. To select a bay, do one of the following:
    • Click within an enclosed area defined by grid lines, or grid arcs.
    • Hold down the left mouse button and drag a box around an enclosed area defined by grid lines, or grid arcs.

Foundation mat properties

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

General
Name The automatically generated name for the mat item.
User Name Can be used to override the automatically generated name if required.
Foundation type Mat
Rotation angle

Specifies the orientation of reinforcement.

Different angles can be specified for different panels within the mat.

See: Rotation angle for slab items and panels
Include in diaphragm If this option is cleared, the mat item does not participate in diaphragm action. All nodes linked to the mat item will be able to displace independently of the diaphragm.
Override slab depth By default all panels in a slab adopt the same depth. Checking this option allows the selected panel to have a different depth and vertical offset.
Vertical offset

Only available when ‘Override slab depth’ is checked.

A positive offset raises the slab panel surface, a negative offset drops it.

Note: Vertical offsets are not structurally significant
Auto-design

For panels in Auto-design mode, As,prov is increased until either a pass is achieved or the limiting reinforcement parameter limits have been exceeded.

For panels not in Autodesign mode, the result will be a pass or fail.
Plane Indicates the level at which the mat is placed.
Slab general
Name The parent foundation mat name.
User Name Can be used to override the automatically generated name if required.
Slab type Foundation mat
Deck type

• Reinforced concrete

• Post tension

Note: Design of post tensioned slabs is beyond scope in the current release.
Decomposition Two-way
Slab parameters
Slab properties
Overall depth Specifies the slab thickness.
Concrete type

• Normal

• Lightweight
Grade/Concrete class Specifies the concrete grade.
Concrete aggregate type Specifies the aggregate type.
Concrete density class For normal weight concrete only, specifies the density class.
Dry density Specifies the dry concrete density
Wet density Specifies the wet concrete density
Diaphragm option
Sets the default diaphragm action for all slab items within the parent slab.
  • Rigid
  • Semi-rigid
  • None
Design parameters

Permanent load ratio

[Displayed for Eurocode only]

 You are required to supply a value for the permanent load ratio parameter. A default of 0.65 has been assumed, but you are advised to consider if this is appropriate and adjust as necessary.

Maximum crack width

[Not displayed for ACI/AISC Regional Code]

 The maximum center to center bar spacing for crack control is dependent on the maximum allowable crack width that is specified here.
Deflection parameters
Restraint constant See: Restraint constant (ACI)
Restraint type

(Eurocode only)

 See: Restraint type (EC2)
Cement class

(Eurocode only)

 See: Concrete Properties (Eurocode)
Soil parameters
Use Ground Bearing Springs Select to specify that the mat is ground bearing.
Allowable Bearing Pressure The allowable bearing pressure is only required when the ‘Use Ground Bearing Springs’ option is selected.
Ground Stiffness The following properties are only displayed when the ‘Use Ground Bearing Springs’ option is selected.
Type

• Spring Linear

• Spring Non-Linear
Stiffness Only displayed when the Type is set to ‘Spring Linear’.
Stiffness -ve Only displayed when the Type is set to ‘Spring Non-Linear’.
Tension limit -ve Only displayed when the Type is set to ‘Spring Non-Linear’.
Stiffness +ve Only displayed when the Type is set to ‘Spring Non-Linear’.
Compression limit +ve Only displayed when the Type is set to ‘Spring Non-Linear’.
Horizontal Support

• Fixed

• Free

• Spring
% of vertical spring stiffness This field is displayed when the Horizontal Support is set to ‘Spring’.
Live/Imposed load reduction
Reduce live/imposed loads by

This property is applicable for the design of transfer slabs and mats.

Although the percentage of live load reduction is not determined automatically, this property allows you to specify the percentage manually.

It can be applied to an individual slab item - you don't have to apply a single value throughout a slab or mat (this can be important if you have discrete transfer panels within a large slab area).

• reducible loadcases are reduced

• combinations incorporating reducible loadcases are reduced

• The reduced results are used in slab design.

Note: For mats, the bearing pressures are reduced as well.
Reinforcement

Slabs panels can potentially have 4 layers of background reinforcement, (however any of the layers/directions can be set to “none” if required).

Select/clear Outside layer in X direction as appropriate to indicate if the outside layer is in the X or Y direction. (The outside layer can be set differently for the top and bottom bars if required.)
Utilization ratio
Apply (to autodesign) On
  • When an Autodesign is performed, the design will be incremented to achieve a utilization ratio less than the ratio limit.
Off
  • When an Autodesign is performed, the design will be incremented to achieve a utilization ratio less than 1.0.

See: Apply user defined utilization ratios
Apply (to check) On
  • When a Check is performed, the check will pass provided the utilization ratio is less than the ratio limit.
Off
  • When a Check is performed, the check will pass provided the utilization ratio is less than 1.0.
Ratio limit The utilization ratio against which the autodesign or check is performed (when applied above).
All edges, Edge 1, Edge 2 etc.
Linear Uncheck in order to specify curved edges.
Curvature

Defines the amount of curvature to all edges.

Only displayed when Linear is cleared.
UDA

Name

Finish

Class

Phase

Note

File

A customizable list of the attributes that can be applied to individual members and panels.

See: Work with user-defined attributes

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