An applied displacement allows a fixed displacement to be applied to a node in the structure and calculates the deformation of the structure which results in the specified displacement at the specified degree of freedom. Thus applied displacements may be used to investigate the stiffness of a structure by constraining certain degrees of freedom to move by a fixed amount and noting the forces involved.
Beam Loads are a ways of applying load to beam members and elements offering the commonly used load patterns as different types. When loads are applied to members, they will be automatically expanded to load the appropriate finite elements.
The following element load types can be created using the respective commands in the Sculpt > Create entity loading menu:
Grid point, line and area loads can be created using the respective commands in the Sculpt > Create grid loading menu. The Create grid loading menu is also available on the right-click menu that is displayed when the cursor mode is set to Polyline. The procedure is broadly the same for creating each grid load type and is as follows.
The following nodal load types can be created using the respective commands in the Sculpt > Create nodal loading menu:
Distortions are used to model the effect of introducing a cut in an element and applying a translational or rotational displacement across the cut.
Edge Loads are loads applied to the edge of 2D elements. In general edge loads should be applied with care to ensure that the loading applied to the element is in a direction in which the element is stiff. Edge loads may not be applied to Flat Plate or Fabric type 2D elements.
Face loads on 3D members or elements are similar to face loads on 2D members or elements, with the additional requirement that the face be selected. Loads are specified as a pressure across the surface.
Face loads should be used where a load distributed over the face of a 2D member or element is required. When loads are applied to members, they will be automatically expanded to load the appropriate finite elements.
Gravity loads are a special case of body loads i.e. loads that apply internally throughout the body rather than being applied externally to the body. Unlike the other load types, gravity loads are an acceleration applied to mass in the structure.
These are area loads located in space or, more precisely, on a grid surface which is located in space. The grid surface is also used to identify the elements that are considered during the grid load expansion. Refer to Specifying Grid Loading for details.
These are line loads located in space or, more precisely, on a grid surface which is located in space. The grid surface is also used to identify the elements that are considered during the grid load expansion. Refer to Specifying Grid Loading for details.
These are point loads located in space or, more precisely, on a grid surface which is located in space. The grid surface is also used to identify the elements that are considered during the grid load expansion. Refer to Specifying Grid Loading for details.
GSA provides a number of different ways to apply loads to a model. The simplest option is nodal loading where forces are applied directly to nodes. This is not recommended for 2D and 3D members or elements.
Node loads are the most fundamental type of load. A node load is a force or moment applied to a particular node or set of nodes. Node loads can be applied in local (i.e. node constraint axis), global or user defined axis directions. User axes can be Cartesian, cylindrical or spherical.
Prestress is a general description covering prestress loads, initial strains and initial lengths. In all cases the result is a prestress condition (set of forces and/or moments) in the member or element.
Prestress loads can be thought of either as prestress forces, tendon prestress applied to the member or element or an initial strain. When loads are specified for members, they will be automatically expanded to load the appropriate finite elements.
A settlement forces a node to move a specified distance in a specified global or local direction in a particular load case, where the node has been restrained in the relevant direction.
In many cases it is useful to consider the effect of thermal loading on a structure. Thermal loads can have two effects. A uniform temperature change causes the entity to expand axially but induces no bending. However, the thermal gradient option defines a linearly varying strain through the thickness of the entity, resulting in both axial expansion and bending. The positions of the temperatures are used to define the temperature gradient.
Thermal loads on 3D members elements can either be uniform giving rise to a uniform thermal strain across the member or element, or variable with temperature specified at each node of an element.
In many cases it is useful to consider the effect of thermal loading on a structure. Thermal loads can have two effects. A uniform temperature change causes the member or element to expand axially but induces no bending. However, the thermal gradient options define a linearly varying strain through the thickness of the member or element so resulting in both in-plane expansion and bending.