1D entity loading

1D entity loading applies to 1D members and elements that are of the beam, bar, tie and strut element type, and to a lesser extent, to cable elements. When loads are applied to members, they will be automatically expanded to load the appropriate finite elements.

There are a number of ways in which loads can be applied but in all cases the loading is resolved during the solution into an equivalent set of nodal forces and moments. When a position along an element is required this may be specified as an actual distance (e.g. 2.46) or as a percentage (25%).

The most commonly used option are beam loads which applies loads at specified positions along the members or elements.

Prestress allows prestress loads to be applied to members or elements. Beams distortions are a different and lesser used option which allows an element to have a displacement discontinuity along the element. This is only valid for linear elements. The final load type for beam elements is thermal where temperature or temperature gradients can be applied to the members or elements.

Load case and title

The loading is stored by case number. However it is good practice to name load cases. The load title gives access to the Load case titles wizard to simplify this procedure. The Wizard is opened for the load cas currently displayed.

How loads are handled for different 1D element types

The 1D entity loading modules are used to specify the load on all 1D members and elements. Not all loads, however, can be applied to all element types. The tables below indicate how loads are handled depending on the element type.

1D loading is applied in four tables in GSA. These are further broken down here as:

Beam loads

• Point force
• Point moment
• Distributed force – uniform, linearly varying, patch, trilinear
• Distributed moment

Prestress

• Prestress – prestress force
• Initial strain
• Lack of fit
• Tendon – tendon prestress
• Tendon with offset

Distortions

• Translational distortion
• Rotational distortion

Thermal

• Uniform thermal
• Thermal gradient

Beam elements

There are no restrictions on beam elements. All load options apply to beams.

Bar elements

	Display in graphics	Result available	Pre-analysis warning	Pre-analysis error	Ignored by solver
Point force	✓	✓
Point moment	✓	✓
Distributed force	✓	✓
Distributed moment	✓	✓
Prestress	✓	✓
Initial strain	✓	✓
Lack of fit	✓	✓
Tendon	✓				✓
Tendon with offset	✓			✓
Translational distortion	✓	✓		if not x
Rotational distortion	✓			✓
Uniform thermal	✓	✓
Thermal gradient	✓			✓

Rod elements

	Display in graphics	Result available	Pre-analysis warning	Pre-analysis error	Ignored by solver
Point force	✓	✓
Point moment	✓	✓
Distributed force	✓	✓
Distributed moment	✓	✓
Prestress	✓	✓
Initial strain	✓	✓
Lack of fit	✓	✓
Tendon	✓				✓
Tendon with offset	✓			✓
Translational distortion	✓	✓		if not x
Rotational distortion	✓	✓		if not xx
Uniform thermal	✓	✓
Thermal gradient	✓			✓

Tie / strut elements

	Display in graphics	Result available	Pre-analysis warning	Pre-analysis error	Ignored by solver
Point force	✓	✓
Point moment	✓	✓
Distributed force	✓	✓
Distributed moment	✓	✓
Prestress	✓	✓
Initial strain	✓		✓	if not tension/compression
Lack of fit	✓		✓	if not tension/compression
Tendon	✓				✓
Tendon with offset	✓			✓
Translational distortion	✓	✓		if not x
Rotational distortion	✓	✓		if not xx
Uniform thermal	✓	✓
Thermal gradient	✓			✓

Cable elements

	Display in graphics	Result available	Pre-analysis warning	Pre-analysis error	Ignored by solver
Point force			✓		✓
Point moment			✓		✓
Distributed force	✓		✓		✓
Distributed moment	✓		✓		✓
Prestress	✓	✓
Initial strain	✓	✓
Lack of fit	✓	✓
Tendon	✓	✓
Tendon with offset	✓			✓
Translational distortion			✓		✓
Rotational distortion			✓		✓
Uniform thermal	✓	✓
Thermal gradient	✓			✓	✓

Link elements

	Display in graphics	Result available	Pre-analysis warning	Pre-analysis error	Ignored by solver
Point force	✓	✓
Point moment	✓	✓
Distributed force	✓	✓
Distributed moment	✓	✓
Prestress			✓		✓
Initial strain			✓		✓
Lack of fit			✓		✓
Tendon			✓		✓
Tendon with offset			✓		✓
Translational distortion			✓		✓
Rotational distortion			✓		✓
Uniform thermal			✓		✓
Thermal gradient			✓		✓

Spring / damper elements

	Display in graphics	Result available	Pre-analysis warning	Pre-analysis error	Ignored by solver
Point force			✓		✓
Point moment			✓		✓
Distributed force			✓		✓
Distributed moment			✓		✓
Prestress			✓		✓
Initial strain			✓		✓
Lack of fit			✓		✓
Tendon			✓		✓
Tendon with offset			✓		✓
Translational distortion			✓		✓
Rotational distortion			✓		✓
Uniform thermal			✓		✓
Thermal gradient			✓		✓