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.
2D entity loading applies to 2D members and elements. When loads are applied to members, they will be automatically expanded to load the appropriate finite elements.
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.
This dialog can be accessed from the “Model > Model tools > Create nodal mass > From grid loads” menu command.
This dialog can be accessed from the Model > Model tools > Create nodal mass > From loads menu command.
Any loading applied to nodes or elements can be deleted using the Sculpt > Delete displayed loading menu command. The procedure is as follows.
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.
This dialog is accessible from the Model > Bridge modelling > Expand bridge loading menu command. This allows the user to generate a series of grid point load equivalent to the static bridge loads and/or moving bridge loads defined in Static bridge load and Moving bridge load tables. Load cases are created in the order of the bridge loads appear in the table. For static bridge loads, the grid point loads generated from each group will have the same load case number. For moving bridge Loads, the grid point loads generated by each increment of the moving bridge load will have a new load case number. Note that changes to the bridge loading table, or to the vehicles and alignments referred to in it will not change the grid point loads already generated.
This dialog is accessible from the Tools > Grid/face loading > Expand grid/face loading menu command. This expands grid loads and maps them to beam loads. Expanding grid loads is not necessary for grid loads to be used in the solution.
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.
This dialog is accessible from the Model > Bridge modelling > Generate static vehicle load menu command. This allows the user to generate a set of loads for a statically positioned vehicle. The origin of the vehicle (normally the centre of the back axle) is positioned is this dialog.
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.
Grid loads are loads that are not applied directly to a node or element, but are located in space or, more precisely, on a grid surface which is located in space. Internally, the load is applied to the structure by considering the location of the load relative to adjacent structural elements.
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.
Three type of nodal loading are possible in GSA. Node loads are the most direct type of loading and apply a force or moment directly to a node. Applied displacements provide a method of determining the state of the structure given a set of fixed displacements at selected nodes. Settlements work with constraints to also provide a way of specifying displacements at specified nodes, but in this cases these are unaffected by any other loads on the structure. Noded to which settlements are applied must be restrained in the settlement directions.
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.
This dialog is available from the Model > Bridge modelling > Optimise path loading menu command. This allows the user to generate a series of static bridge loads, based on the results of an influence analysis and the data in the path loading module. For each node influence effect, beam influence effect and each entry in the Path loading table, two groups of Static bridge loads are generated, to give the most positive and most negative effect (force/displacement/reaction). Each of these groups can then be used to generate a load case comprising grid point loads using the Expand bridge loading tool.
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.
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.