A NodeLoad object represents a force or moment load applied to a node within the structure.  All the nodal loads applied in a particular load case are stored in a NodeLoads collection.  These loads can be accessed via the NodeLoads property of the LoadCase object.  The properties and methods of the Node object are listed below.

The Application, Frame, Number, Label and Index properties as well as the Delete method are common to many objects and are described in Chapter 2.

A nodal force loading is added to a load case using the AddLoad method of the NodeLoads collection.  The first parameter of this method accepts a variant value that specifies the node at which the load is to be applied.  This parameter may specify the node by either its integer index or by using a Node object.  The next two parameters are optional and specify the direction of the load and it’s magnitude, which is set using the current force or moment units set within the Multiframe application.  The AddLoad method returns a NodeLoad object that references the new load added to the structure.  For example, the following demonstrates how to add node loads to a structure.

Dim myLoad as Multiframe.NodeLoad

With myFrame.LoadCases(1)

  ’Add load of magnitude 10.5 units to node 12 in the x direction
  set myLoad = .NodeLoads.AddLoad(12,mfDOFx,10.5)

  ’Add load of magnitude 4.5 units to node 7 in the y direction
  set myLoad =.NodeLoads.AddLoad(myFrame.Nodes(7),2,4.5)

End With

The AddLoad method can also take an extra optional parameter that specifies if the load is to be applied in the global or the local nodal coordinate system.  By default, all node loads are added in the local nodal coordinate system.

Groups of nodal forces can be created using the AddLoads method of the NodeLoads collection.  This method returns a NodeLoadList containing each of the loads added to the frame.  The parameters of this method correspond to the parameters of the AddLoad method except that each parameter may be either an array, containing values for each of the new loads, or a single value that will be applied to each of the new loads.  Several examples of how this method may be used are as follows:

Dim myLoads as New Multiframe.NodeLoadList
Dim myNodeLoads as Multiframe.NodeLoads
Dim myVar as Variant

’Get reference to node loads collection
set myNodeLoads = myFrame.LoadCases(1).NodeLoads

’Add a single load
set myLoads = myNodeLoads.AddLoads(12,mfDOFx,10.5)

’Add the same load at nodes 1,2 and 5
set myLoads = myNodeLoads.AddLoads(Array(1,2,5),mfDOFx,10.5)

’Add two loads at node 12
myVar=Array(mfDOFx, mfDOFy)
set myLoads = myNodeLoads.AddLoads(12,myVar,Array(7.5,5.5))

’Add two loads
set myLoads = myNodeLoads.AddLoads(Array(4,5),myVar,Array(7.5,5.5))

’Add a single load to each node in frame
set myLoads = myNodeLoads.AddLoads(myFrame.Nodes,mfDOFx,2.75)

The first parameter of the AddLoads method is a variant parameter identifying the nodes to which the loads are to be applied.  This parameter may specify the nodes by an integer index, an array of integer indices, a Node object, a NodeList, or a Nodes collection.

A nodal load can be modified via the NodeLoad object.  This object has properties describing the node to which the load is applied, the direction, magnitude and the axis to which the loading is orientated.

The node at which the load is applied is identified by the Node property of the NodeLoad object.  This property returns the Node object corresponding the node at which the load is applied.  This property may be set to a new value using any variant value representing a node.

The DOF property controls the direction in which the load is applied.  The property is an enumerated value of type mfDOF.  Nodal force loads are applied with a DOF set to mfDOFx, mfDOFy or mfDOFz that describes the direction in which the load is applied.  Nodal moment loads are specified with a DOF of mfDOFthetax, mfDOFthetay or mfDOFthetaz.  The axes to which these degrees of freedom refer are specified by the Global property.  If this Boolean property is true then the load is applied in the direction of the global coordinate axes.  If the Global property is false, the load is directed along the local nodal axes that are specified by the nodal orientation.  The direction and axes of the loading may also be specified using the Kind property.  This property is a character string describing the direction of loading and the axes to which the load is applied.

The magnitude of the load is stored in the Value property of the NodeLoad object.  The value of this property describes the magnitude in terms of the force or moment units currently set within the Multiframe application.  An example of how these properties may be changed is as follows

Dim myLoad as Multiframe.NodeLoad
 
’Get reference to node load
set myLoad = myFrame.LoadCases(1).NodeLoads(4)

’Change load to 10.5 unit load applied in global z direction
myLoad.DOF = mfDOFz
myLoad.Value = 10.5
myLoad.Global = true

’Change direction such that load applied in local x direction
myLoad.Kind = ”Px’”