ProtaStructure : Working With Space Truss

Working With Space Truss

This function can specify a region and insert a space truss parametrically. You can control parameters such as cell size, number of rows and columns, curvature and more.

Inserting a Space Truss

To insert a steel space truss:

1. Pick the Space Truss command on the Modeling > Steel Members ribbon tab.



2. Draw a rectangular area on the screen where the space truss will be placed.
Space trusses can only be placed in a rectangular area.



3. The parametric Space Truss Editor will be launched. On this editor, you can control the parameters for top and bottom surface separately. Additionally, you can change the steel profile to be used in space truss, define uniform loads and change number of truss grids.


                                                                               


Framing Type

You can select Reducing or Increasing option for auto-generation of space truss pattern.

The icons on the toolbar:
Reducing option creates bottom surface larger than the top surface
Increasing option creates top surface larger than the bottom surface



Top Surface and Bottom Surface Shape

The space truss module allows you to specify different curvature for top and bottom surfaces of the truss. 

Planar, cylindrical and spherical surfaces can be selected. 

  

Adjusting Grid & Offset

You can specify number of grids (space truss triangular modules) in terms of Column Count and Row Count. You can also enter an offset value in Z direction to shift the entire truss. 



Click Generate to apply changes on the space truss.

Space Truss Parameters

The parameters on the left panel will change depending on the surface type.

Elevation : Height of the space truss. Only shown when planar surface is chosen.
Column Count : Number of grids in X-direction
Row Count : Number of grids in Y-direction
Z Offset : Offset height from the supporting column



Start Radius : Radius of the curvature at the start in X-direction
End Radius : Radius of the curvature at the end in X-direction
Start Center Z : Height of the space truss at the start point. To be used to set the height of the top and bottom surface of the space truss for cylindrical and spherical surface.
End Center Z : Height of the space truss at the end point. To be used to set the height of the top and bottom surface of the space truss for cylindrical and spherical surface.



Start Center X : Center of space truss from the space truss starting point in X-direction 
Start Center Y : Center of space truss from the space truss starting point in Y-direction 
End Center X : Center of space truss from the space truss ending point in X-direction 
End Center Y : Center of space truss from the space truss ending point in Y-direction 



Changing Profiles

You can change the steel profile to be used in truss rods using the Section button under Loads tab.



Applying Loads on Space Truss

The self-weight of the truss members itself is automatically calculated. We have provided fields for easy application of uniform loads on truss cladding.

The cladding that facilitates the load transfer will be automatically inserted on the space truss and is an inseparable part of the truss, thus it cannot be deleted. Apart from the uniform loads specified in the space truss editor, You can assign any loads on the space truss using the ProtaStructure Load Editor.

 

Self-Weight: Enter the self-weight of the cladding in this field. The self-weight will depend on the type of the cladding profile.

Dead Load: Enter the additional dead loads (finishes etc.) in this field.
The library editor for Dead Load is in Building Setout > Libraries > Slab Additional Loads ribbon tab.

Live Load: Enter the live loads in this field. You can access a quick list of imposed load values by clicking the small button next to Live Load field. 

The cladding loads library is provided for easy application. The library can be accessed by clicking the small button next to Self-Weight, Dead Load and Live Load field.

Roof Live Load, Snow Load and Rain Load fields will be activated if the associated load cases are defined in the Load Combinations Editor. 

Applying Loads on Space Truss via Load Editor

If you want to add further loads on the space truss, you can do so by using the ProtaStructure Load Editor.

1. Select the space truss on the screen
2. Right click and pick Edit Loads command.



 3. On the load editor you can assign Uniform Area Loads on any region on the truss cladding or Point Loads on any joint under any load case (except seismic and notional load cases)



For more details of load editor, kindly refer to Load Editor.

Extending Top of the Columns to Space Truss

We also enhanced existing features around recently introduced ones. For example, you can extend an existing column to a selected space truss. So that it becomes very easy to place the intermediate supports after space truss insertion. To extend a column to a space truss:

1. Select the column and pick “Extend Column to Member” command on the right-click menu.

2. Pick the space truss.

3. The extend command will calculate the nearest point on the bottom surface of the space truss and assign a Del Z-Top value to the column.







After you analyze the building with space truss, you can continue with designing the space truss members. There is a dedicated design interface where you can check the sub members and control the whole process in a well-coordinated environment.

To access the space truss design:

1. Select the space truss member

2. Pick the Steel Member Design command on the right click menu

3. Click Check All button to design all space truss sub members. The steel design will take place for sub members using a multi-threaded approach utilizing computer’s all available CPU cores.

4. Alternatively, you can access the design of all space trusses via Design > Space Trusses ribbon tab.




ProtaStructure can only design the members of a space truss. Ball & Socket joint design is currently out of ProtaStructure and ProtaSteel’s scope.





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