Open the Load Definition dialog, which defines loads from predefined load cases, using either method:
- Click Loads menu > Load Definition
- Click
.
The dialog has 4 tabs:
Node
When the Node tab is selected, the dialog displays the following buttons:
- Opens the dialog for defining nodal force.
- Opens the dialog for defining imposed displacements for support nodes.
- Opens the dialog for defining the values of forces at a point in a structure (available for: plate and shell structures, plane stress and plane deformation structures, axisymmetric structures, and volumetric structures).
- Deletes a nodal load type. To remove a load from a structure, select the load type to be deleted and indicate the nodes from which to delete the load.
Bar
When the Bar tab is selected, the dialog displays the following buttons:
- Opens the dialog for defining uniform loads.
- Opens the dialog for defining trapezoidal loads.
- Opens the dialog for defining uniform moment loads.
- Opens the dialog for defining concentrated loads along the element's length.
- Opens the dialog for defining dilatation values.
- Opens the dialog for defining thermal loads.
- Opens the dialog for defining planar loads.
- Deletes a nodal load type. To remove a load from the structure, select the load type to be deleted and indicate the bars from which to delete the load.
Surface
When the Surface tab is selected, the dialog displays the following buttons:
- Opens the dialog where uniform loads acting on planar finite elements can be defined.
- Opens the dialog where linear loads acting on planar finite elements can be defined.
- Opens the dialog where planar loads (on 3 points) acting on planar finite elements can be defined.
- Opens the dialog where loads due to hydrostatic pressure acting on planar finite elements can be defined.
- Opens the dialog where uniform loads acting on a contour can be defined.
- Opens the dialog where planar loads (on 3 points) acting on a contour can be defined.
- Opens the dialog where thermal loads acting on planar finite elements can be defined.
- Opens the dialog where load on edges can be defined.
- Deletes the type of load acting on planar finite elements. To remove a load, select the load type to be deleted and indicate the elements from which to delete the load.
Self-weight and mass
After the Self-weight and mass tab is selected, the dialog displays the following buttons:
- Automatically applies self-weight to all structure elements. The load acts along the Z axis of the global coordinate system. Its orientation is opposite to the axis orientation (See also: Comments concerning automatic assigning of a self-weight load to a whole structure).
- Opens the dialog in which the direction of self-weight action can be defined.
- Opens the dialog in which body forces can be defined.
- Opens the dialog in which centrifugal and angular acceleration forces can be defined.
- Opens the dialog in which the values of nodal masses can be defined.
- Opens the dialog in which the values of bar masses can be defined.
- Deletes the self-weight load. To remove a load, indicate the elements from which the load is to be removed.
New types of loads let you define body forces, centrifugal and angular acceleration forces, so you can analyze and design structures for the marine industry. These structures are associated with extracting crude oil from the bottom of the sea, such as, components for equipment on drilling platforms. These loads generate structural inertia forces, because of assigned velocity or acceleration. This type of load applies to marine structures, where transport loads are very important, such as, a structure lifted by a crane or mounted on a ship. Although these types of loads do not solve all problems when modeling marine structures, they make the modeling easier.
The Robot program defines masses (weights) added to nodes and bars, as well as conversion of loads to masses. Added masses are primarily used in dynamic analyses (dynamic, harmonic, spectral, seismic, and time history), but they need to be considered in static calculations when generating forces for body loads and self-weight, as follows:
- The table of added masses is available if any load case has been defined.
- Options for added masses (nodal and bar masses) are always available in the dialog.
- In the mass table and the Analysis Type dialog on the Load to Mass Conversion tab, a complete list of simple load cases is available.
An added mass influences a given load case, when one of the following loads is defined (these are loads generating forces from added masses):
- Self-weight
- Body forces
- Centrifugal and angular acceleration forces.
The top of the dialog has information about the load case (name and number) for which to define the load, and the type of load to be assigned to nodes or bars in the structure.
After the load type is specified, the load can be assigned to structure nodes or bars using one of the following ways:
- Enter numbers of the nodes or bars in the Apply To field and click Apply.
- Add the defined load to consecutive nodes or bars in the structure (the cursor will change its shape to the load symbol).
- Select the nodes or bars graphically and click Apply.