Create a truss

The Truss Wizard helps you to create trusses in your models. For detailed instructions on how to use the Truss Wizard to create trusses, see the following instructions.

On the Model ribbon, open the truss/space/freeform list in the Steel, Timber, or Cold Formed group according to your needs.
Click Truss (for steel and cold formed), or Truss (for timber).

The Truss Wizard opens.
Select the truss shape.
In the model, click the start point of the truss.
Tip: If you are using a point along a member, do the following:
1. Click the member to view its points.
2. Click the point that you want to use, or type the distance from the start of the member to the desired point.
In the model, click the end point of the truss.
In the Truss Wizard, click Next.
Specify the truss alignment parameters.
Click Next.
Specify the truss details.
Click Finish.

Create a space truss

Tekla Structural Designer allows you to create linear and planar space trusses. You can create space trusses in a 2D or 3D view. For more information, see the following instructions.

On the Model ribbon, open the truss/space/freeform list in the Steel, Timber, or Cold Formed group according to your needs.
Click Space

The Space Truss Wizard opens.
Define the truss type, the alignment, and the number or bays.
Click Next.
In the model, click the truss location points:
- For a linear truss, click the start and end points.
- For a planar truss, click the four corners of the truss.
In the Space Truss Wizard, specify the truss width and height.

If you are creating a planar truss, Tekla Structural Designer calculates the width automatically.
Click Next.
Define whether the truss should be straight or curved.
Click Finish.

Create a free form truss

You can create a free form truss by placing a series of truss members in the required shape. For more information, see the following instructions.

Restriction:

Free form trusses cannot be created in a 3D view, or a 2D level view.

Open the 2D frame view in which you want to create the truss.
On the Model ribbon, open the truss/space/freeform list in the Steel, Timber, or Cold Formed group according to your needs.
Click Free Form
Click the start point of the first truss member.
Click the end point of the first truss member.
Repeat steps 4 and 5 to place each truss member as required.
When the truss geometry is complete, press Esc to finish.

Modify the geometry of an existing truss

After creating a truss you can modify its geometry by using the Edit command. For more information, see the following instructions.

Hover the mouse pointer over the desired truss so that it becomes highlighted.
Right-click the truss.
In the context menu, select Edit [element name].

Depending on the type of the truss, either the Truss Wizard or the Space Truss Wizard opens.
Modify the truss properties according to your needs.
To save the changes, click Finish.

Modify the properties of existing trusses

You can modify the section sizes, material grades, section orientations, and other truss properties in the Properties window. For more information, see the following instructions.

Move the mouse pointer over the desired truss, so that it becomes highlighted.
Click the truss.
In the Properties window, modify the truss properties according to your needs.

Steel truss member properties

Properties are listed below in the order that they appear in the Properties window.


General
Name	The automatically generated name.
User Name	Can be used to override the automatically generated name if required.
Plane	Indicates the level or frame within which the member is placed.
Characteristic	Truss internal Truss member side Truss member top Truss member bottom
Element type	Beam
Material type	Steel
Construction	The available construction options depend on the characteristic and material type selected, see Member characteristic, construction and fabrication properties
Fabrication	The available fabrication options depend on the characteristic and material type selected, see Member characteristic, construction and fabrication properties
Autodesign	See: Steel member autodesign
Design section order [Only displayed when 'Autodesign' is selected]	The design order file from which a section size will be selected. For details of managing order files, see: Manage design section orders
Rotation	Rotation of the member about its local x axis. The default (Degrees0) aligns the major properties with the global Z axis, (provided that the member has not been specifically defined within an incline plane).
Alignment
Global offset end 1, end 2	Can be used to model a physical offset with respect to the global axes at one or both ends of the member, (exceptions apply). See: Member global offsets
Major snap level, Minor snap level	Defines the major and minor alignment of the member relative to the insertion point.
Major offset, Minor offset	Used to offset the member from the snap point in the major and minor axis.


Truss general
Name	The automatically generated name of the parent truss assembly.
User Name	Can be used to override the automatically generated name if required.
Material type	Steel
UDA
Name Finish Class Phase Note File	A customizable list of the attributes that can be applied. See: Work with user-defined attributes


Span
Section	The section size
Geometry (automatic design) [Only displayed if Autodesign is selected]	The cross section type to be designed
Grade	Steel grade
Compression only, Tension only [Only displayed for Truss Internals]	Specify if the truss internal is compression only, or tension only. Note: Tension only and Compression only members are non-linear elements and therefore require non-linear analysis. If linear analysis is performed they will be treated as linear elements
Linearity	Straight
Top flange cont. rest. [Only displayed for Truss Top & Bottom members]	Define if the top flange is continuously restrained.
Bottom flange cont. rest. [Only displayed for Truss Top & Bottom members]	Define if the bottom flange is continuously restrained.
Releases
Fixity end 1, end 2	Pinned Fully Fixed Moment pin (Mz) [Fully Fixed, and Moment pin (Mz) are only available for Truss Top & Bottom members]
Cantilever end 1, end 2 [Not displayed for Truss Internals]	Check one end only to define a cantilever end.
Axial load release end 1, end 2 [Not displayed for Truss Internals]	Check one end only to define an axial release.
Torsional load release end 1, end 2	Check one end only to define a torsional release.
Wind loading
Apply open structure wind load	Select this option if you want open structure wind loads to be calculated. See: Open structure wind loads
Shape factor, Cf	The default shape factor varies according to the entity type and is taken from Model Settings > Loading > Wind Loading Default Cf factors are taken from the document ‘Wind Loads For Petrochemical And Other Industrial Facilities’ published by ASCE.
Effective area XY
Formula	The default effective area formula varies according to the entity type and is taken from Model Settings > Loading > Wind Loading
Factor	The factor used in the above formula can be edited if required.
Effective area XZ
Formula	The default effective area formula varies according to the entity type and is taken from Model Settings > Loading > Wind Loading
Factor	The factor used in the above formula can be edited if required.
Live Load Reduction [ACI/AISC]
KLL	Specify the KLL factor in accordance with Table 4-2 in ASCE 7-05/ASCE 7-10. See: Overview of live or imposed load reductions
Imposed Load Reduction [Codes other than ACI/AISC]
Reduce imposed loads by	This property is particularly applicable to the design of transfer beams. Although the percentage of imposed load reduction is not determined automatically for beams, this property allows you to specify the percentage manually. It can be applied to all, or individual spans. reducible loadcases are reduced combinations incorporating reducible loadcases are reduced The reduced results are used in concrete beam design. See: Overview of live or imposed load reductions
Compression
Effective length factors	Specified as Kx, Ky for ACI/AISC. Effective length factor y-y, z-z for other codes.
Tension
Net area	Specified as an effective net area or a percentage value.
Deflection limits [Only displayed for Truss Top & Bottom members]
Apply span\factor	With this option checked, the limit can be defined as a Relative span/factor.
Apply abs. limit	With this option checked, the limit can be defined as an absolute value.
Size constraints
Max depth, Min depth, Max width, Min width	Size Constraints are only applicable when Autodesign is checked. They allow you to ensure that the sections that Tekla Structural Designer proposes match any particular size constraints you may have. For instance for a composite beam you may want to ensure a minimum flange width of 150mm (6in). If so you would simply enter this value as the Minimum width, and Tekla Structural Designer would not consider sections with flanges less than this width for the design of this beam. See: Size constraints
Apply max span/depth ratio Max span/depth ratio	After setting a max span/depth ratio you can check the 'Apply' button for it to be considered by auto-design. During design, only sections which satisfy the maximum ratio limit will be selected. The setting can also be reviewed and/ or copied via Review View > Show/Alter State. See: Size constraints
Instability factor
Prevent out of plane instability	Define if out of plane stability is prevented. See: Instability factor
End 1 / End 2 [Only displayed for ACI/AISC regional code]
Apply SidePlate connection	Select to apply a side plate connection at the specified end(s).
Utilization ratio
Apply (to autodesign)	Selected - When an Autodesign is performed, the design will be incremented to achieve a utilization ratio less than the ratio limit. Unselected - 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)	Selected - When a Check is performed, the check will pass provided the utilization ratio is less than the ratio limit. Unselected - 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).
Fire proofing
Protected	When Protected is selected, self-weight of the members is increased by the weight of fireproofing. See: Fire proofing
Exposure	Exposed on all sides
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

Timber and cold formed truss member properties