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Equipment

Tekla Structural Designer
2021
Tekla Structural Designer

Equipment

Equipment is primarily intended for use in industrial structures, enabling the quick and efficient application of loading from plant items, tanks & cylinders etc. - that are not part of the main structural frame.

Overview

Equipment can be displayed in Tekla Structural Designer in the form of a sphere, vertical cylinder, horizontal cylinder or cuboid.

Equipment has an associated Center of Gravity (CoG) which is indicated by the user co-ordinate system (UCS) as shown above.

Equipment also has a number of support points through which load is transferred to the structure. At least three support points are required and there is no limit on the maximum. The area bounded by these support points is referred to as the 'Loading Area'.

The support points are numbered and become active when the equipment is selected. Unnumbered nodes at the mid-points of loading area edges also become active.

Equipment support points and loading area

Equipment

Loading area

Support points

Unnumbered node

Note: Unnumbered nodes are provided to facilitate editing of the Loading Area - they are not support points.

The 3D geometry, UCS and loading area can be switched on or off for each equipment shape within Scene Content.

Once placed, equipment is listed in the Project Workspace Structure Tree under the Loading Elements group.

Modeling

Equipment must be defined in the horizontal plane.

Once it has been defined, you can alter the shape of the loading area by dragging any of its nodes. Dragging a numbered support point moves it, dragging an unnumbered node (as shown below) introduces a new support point.
By default the CoG of the equipment and the CoG of the support points coincide. You can specify an offset to the equipment CoG to facilitate the adjustment of equipment loads on the structure.

Equipment must be placed in such a way that each support point is itself supported by a structural item or slab item.

No member, ancillary, slab, wall or other equipment may be attached to an equipment entity.

Equipment loadcases

Equipment loads have three dedicated gravity loadcases which are automatically added and removed as the loads are added/deleted.

  • Equipment Empty
  • Equipment Operating Content
  • Equipment Testing Content

These dedicated loadcases specifically aid combination building for Industrial design.

Note: For Equipment Operating & Testing Content Loadcase Types, you can select whether these are considered as Dead or Imposed (Live) loads from Model Settings > Loading > General.

When equipment is added, initially the loads in the dedicated loadcases default to zero. When the load is specified it can either be applied at the CoG of the equipment, or at the equipment support points. This is important when the CoG is different between the loaded and unloaded conditions.

Once equipment has been defined, additional horizontal or vertical point loads can be applied to it in other dead and imposed/live loadcases.

The Equipment load command for doing this is located in the Structure Loads group on the Load tab on the ribbon.

Equipment load decomposition

All decomposed loads from equipment are present in the analysis and design.

Once loads are decomposed the equipment itself plays no further part in analysis and design.

Equipment decomposition for loads applied at CoG

Decomposition is in two stages: from the equipment to the equipment support points, then into the structure.

For each equipment, the load distribution distributes the total load proportionately to the equipment support points based on an iterative decomposition approach in which the loading area acts as rigid.

Note: The distribution of a point load applied to a rigid plate is a very complex problem to solve, if done by FE then results are determined by stiffness of the plate. The iterative approach is approximate but believed to be sufficiently accurate for the purpose. If you do not want to use this approach, the loads should be applied at supports instead.
In the following example equipment is placed on a one-way slab which spans in the global X direction. The equipment has 4 support points positioned symmetrically about the slab center-line. A load of 10kN is applied at the equipment CoG.
When the model is analyzed the equipment load is decomposed to the equipment support points, then on to the supporting members as shown below.
  • Stage 1 - the 10kN load is decomposed to the 4 numbered support points, due to symmetry these each receive 2.5kN.
  • Stage 2 - support point loads are decomposed on to the members supporting the slab. Again due to symmetry, the resulting member point loads are each 2.5kN
If the CoG of the equipment is offset along the global X axis so that it now lies at the edge of the loaded area, when the model is re-analyzed the decomposed loads are updated as shown below:
  • Stage 1 - because the CoG has been offset, support points 2 and 3 each receive 5kN whereas support points 1 and 4 remain unloaded.
  • Stage 2 - support point loads are decomposed on to the members supporting the slab, resulting in 2 point loads of 1.25kN on the left, and 2 point loads of 3.75kN on the right.

Equipment decomposition for loads applied at supports

In this case, only the second stage decomposition is required on to the supporting members.

Create equipment and equipment loads

  1. Open a 3D View, or 2D Level View in which to create the equipment.
    Note: Equipment must be defined in a horizontal plane, and so cannot be created in a 2D Inclined Plane View.
  2. On the Model tab, click Equipment.
  3. In the Properties window, define the equipment shape and size:
    1. Select the required Type.
    2. Enter the geometric properties (Length, Breadth, Height, or Diameter) required to define the size.
    3. Leave Base position, z as 0 to place the equipment directly on it's loaded plane, or enter a non-zero value to raise/lower it.
    4. Leave Angle to Global X as 0 , or enter an angle to rotate it.
  4. In the Properties window, select whether the empty, operating content, and testing loads are to be applied at the center of gravity of the equipment, or through the supports.
  5. Define the equipment load values:
    • If applied At CoG, enter each value.
    • If applied At Supports, click the ellipsis buttonthen enter the required value at each support.
  6. In the 3D or 2D View, click the start point of the loaded area.
  7. Click the remaining points of the loaded area.
  8. To define the end point of the loaded area, do one of the following:

    • Double-click the end point.

    • Click the end point, and click the start point again.

    Note: At least three support points are required, no limit on maximum.

    Tekla Structural Designer creates the equipment positioned at the center of gravity of the loaded area.

Create additional equipment loads in other loadcases

Once equipment has been defined you can apply additional loads to it in loadcases other than the dedicated 'equipment' ones. These loads can be applied in any global or local direction.
  1. In the Loading list, select an appropriate loadcase.
    Note: This cannot be one of the existing dedicated 'equipment' loadcases.
  2. On the ribbon, go to the Load tab.
  3. Click Equipment.
  4. In the Properties window, select the load direction.
  5. In the Properties window, select whether the load is to be applied at the center of gravity of the equipment, or through the supports.
  6. Define the load value:
    • If applied At CoG, enter the load value and the Offset from mid height above or below the loaded area at which the load is to be applied.
    • If applied At Supports, click the ellipsis buttonthen enter the required value at each support.
  7. In a 2D or 3D View, pick the equipment to apply the load to.

Generate equipment combinations

If you are going to generate combinations automatically you will need to make use of combination 'scenarios' to prevent equipment empty, operating content and testing content loadcases from being included in the same combination. The steps for doing this are as follows:
  1. On the Load tab, click Loadcases.
    The Loading dialog box opens on the Loadcases page. On this page, you can see the loadcases that have been created and select which ones are to include when combinations are generated.
  2. To generate combination(s) for the equipment empty loadcase, check 'Include in Generator' for Equipment Empty but uncheck the other equipment loadcases.
  3. At the top of the dialog, click Combinations.
  4. Click Generate.
  5. In the Combination Generator, enter an appropriate name for the 'empty' scenario and select the Replace only combinations generated by this run option.
  6. Make appropriate selections to generate the combination(s) required for this scenario, then click Finish to see the result.
  7. Click Loadcases to return to the Loadcases page.
  8. Check 'Include in Generator' for Equipment Operating Content but uncheck the other equipment loadcases.
  9. On the Combinations page, click Generate.
  10. In the Combination Generator, enter an appropriate name for the 'operating' scenario and select the Replace only combinations generated by this run option.
  11. Make appropriate selections to generate the combination(s) required for this scenario, then click Finish to see the result.
  12. On the Loadcases page, check 'Include in Generator' for Equipment Testing Content but uncheck the other equipment loadcases.
  13. On the Combinations page, click Generate.
  14. In the Combination Generator, enter an appropriate name for the 'testing' scenario and select the Replace only combinations generated by this run option.
  15. Make appropriate selections to generate the combination(s) required for this scenario, then click Finish to see the result.
  16. Click OK

Create an equipment loads report

A table of the equipment loads applied to the model is available in the Industrial Structure Loading report, which is created as follows:

  1. On the ribbon, go to the Report tab.
  2. In the list on the left side, select Industrial Structure Loading.
  3. Click Show Report.
    Tip: If the resulting report displays too little or too much information, adjust the content by re-configuring the report.
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