Create supports

Tekla Structural Designer
Modified: 12 Nov 2024
2024
Tekla Structural Designer

Create supports

Supports allow you to constrain points in your structure positionally and rotationally. In addition, you can change the fixity provided at an existing support by modifying the support properties.

Create a single support

Restriction:

You can only place supports at existing grid points.

  1. On the Model tab, click Support.

    The support will adopt the properties currently displayed in the Properties window.

  2. If necessary, in the Properties window, adjust the support properties.
  3. Click the grid point where you want to create the support.

Create a rotated or inclined support using 3 grid points

You can create a rotated support as follows:

  1. On the Model tab, click Support.
  2. Go to the Properties window.
  3. Ensure that the 3 Grid Points option is selected.
  4. Click the grid point where you want to create the support.
  5. To define the support direction along the x axis, click a second point.
  6. Lastly, define the plane containing the x and y axes by clicking a third point.
    The support is created with its x axis in the direction specified by the second point, and its y axis at 90 degrees to the x axis within the plane defined by the first, second and third points.

Create spring supports

You can create linear and non linear spring supports in a similar fashion.

  1. On the Model tab, click Support.
  2. Go to the Properties window.
  3. Ensure that in the direction where you want the spring to act, the degree of freedom is set to Free.
  4. In the appropriate stiffness properties, do one of the following:
    • Select the Spring Linear option, and define a single stiffness value that acts in both the positive and negative directions.

    • Select the Spring Non-linear option, and define two stiffness values, one to act in the positive direction and another to act in the negative direction.

  5. Click the grid point where you want to create the support.

Create nominally pinned or nominally fixed supports

A support placed under a column is a special case which can be specified as nominally pinned, or nominally fixed if required.
Note: A validation error is produced if a nominally pinned or nominally fixed support is placed at any other location.
  1. On the Model tab, click Support.
  2. Go to the Properties window.
  3. Ensure that the Mx and/ or My directions about which you require partial fixity are set to Free.
  4. In the appropriate rotational stiffness properties, do one of the following:
    • Select the Nominally pinned option, and define the required stiffness value as a percentage of the column stiffness 4EI/L.

    • Select the Nominally fixed option, and leave the stiffness value as 100% of the column stiffness 4EI/L.

  5. Click the grid point where you want to create the support.

Support properties

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

Property Description

General

Name

Automatically created name based on the grid point location.

Note: This property is only displayed when editing an existing support

User Name

You can enter a user name to replace the automatically created name if required.

Note: This property is only displayed when editing an existing support

Plane

Describes the level at which the support was placed.

Note: This property is only displayed when editing an existing support

3 Grid Points

The options are:

  • Checked

    A user defined coordinate system is applied to the support. (After clicking where you want to create the support, the second click defines the x direction and the third click defines the y direction.)

  • Unchecked (Default)

    Support properties are defined in accordance with the global coordinate system.

Note: This property is only displayed when creating a new support

Fx, Fy, Fz

The translational degrees of freedom can be set as either Free, or Fixed in each direction.

Mx, My, Mz

The rotational degrees of freedom can be set as either Free, or Fixed in each direction.

Angles

Inclination, Azimuth and Rotation

When creating new supports, the angles are calculated automatically depending on the placement method (3 Grid Points Checked/Unchecked).

When editing existing supports, the angles can be edited in order to redefine the direction in which the support acts.
  • Inclination - inclination about Global X
  • Azimuth - rotation of inclined support about Global Z
  • Rotation - rotation about the support local z axis

For more information, see: Rotated and inclined supports

Translational stiffness x, y, and z

Type

In order to define a translational spring in a particular direction, the translational degree of freedom in the same direction must first be set to Free. The available types are:

  • Release - (i.e. zero translational stiffness)
  • Spring Linear
  • Spring Non-linear

Stiffness

The options are:

  • Spring Linear

    A single stiffness value is entered, which acts in both the positive and negative directions.

  • Spring Non-linear

    Two stiffness values are entered, one to act in the positive direction and a second to act in the negative direction.

Fmax -ve and Fmax +ve

For non-linear springs you are also able to define the spring capacity in each direction. (Note that this must always be entered as a positive value, for both +ve and -ve directions).

Rotational stiffness x, y, z

Type

In order to define a rotational spring in a particular direction, the rotational degree of freedom in the same direction must first be set to Free. The available options are:

  • Release - (i.e. zero rotational stiffness)
  • Spring Linear
  • Spring Non-linear
  • Nominally Pinned
  • Nominally Free

Stiffness

The options are:

  • Spring Linear

    A single stiffness value is entered, which acts in both the positive and negative directions.

  • Spring Non-linear

    Two stiffness values are entered, one to act in the positive direction and a second to act in the negative direction.

Stiffness Percentage

The options are:

  • Nominally Pinned - 10%

    (i.e. 10% * 4 EI/L)

  • Nominally Fixed - 100%

    (i.e. 100% * 4 EI/L)

Note: In the above equations, L is the length from the base of the column to the level of the next column stack that is denoted as a floor, or it is the distance to the top of the column if shorter.

Fmax -ve and Fmax +ve

For non-linear springs you are also able to define the spring capacity in each direction. (Note that this must always be entered as a positive value, for both +ve and -ve directions).

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