Obtaining Applied Loads Obtaining Applied Loads

If the goal of entering the Structural Menu was to generate a set of applied loads, one should first issue the appropriate LCASE commands, and then select the portion of the model for which he wishes to generate the loads. If the loads for the entire model are desired, then no further action is necessary. If, however, loads on only a portion are desired, the loads generated can be limited by the commands:


     S_PART,  PART_NAME(1), PART_TYPE(1), .. PART_NAME(n), PART_TYPE(n)

     S_BODY,  BODY_NAME(1), BODY_NAME(n), .....

Here, PART_NAME(i) and BODY_NAME(i) are the part and/or body names to be selected, and PART_TYPE is the type of the part, and all can contain wild characters. When using S_PART, a part will be selected only when both part name and type match that of a PART_NAME(i) and PART_TYPE(i).

After the load cases and the model have been defined, one then exports the loads by simply issuing the command:


     EXP_ALOAD

and MOSES will write the loads applied to the selected system to a file for use elsewhere. By default, this file will be named root.ppo. The user may override this name by using the proper options of the &DEVICE command. There are three basic components to this file: the load case name, nodal loads (if present) and element loads. A sample of this file is:

$&DIMEN -DIMEN  Feet     Kips
$APLOAD
LOAD CASE TWO
*2        6.4185E-16  6.4185E-16 -1.0000E+01  0.0000E+00  0.0000E+00  6.4185E-14
*3        6.4185E-16  6.4185E-16 -1.0000E+01  0.0000E+00  0.0000E+00  6.4185E-14
ELMAPL     T        ~T       *1       *2             .00     10.00
     0.0000E+00  0.0000E+00 -3.8378E-02  0.0000E+00  0.0000E+00  0.0000E+00
     0.0000E+00  0.0000E+00 -3.8378E-02  0.0000E+00  0.0000E+00  0.0000E+00
ELMAPL     T        ~T       *1       *2           10.00    131.42
     0.0000E+00  0.0000E+00 -4.2654E-02  0.0000E+00  0.0000E+00  0.0000E+00
     0.0000E+00  0.0000E+00 -4.2654E-02  0.0000E+00  0.0000E+00  0.0000E+00
ELMAPL     T        ~T       *1       *2          131.42    141.42
     0.0000E+00  0.0000E+00 -3.8378E-02  0.0000E+00  0.0000E+00  0.0000E+00
     0.0000E+00  0.0000E+00 -3.8378E-02  0.0000E+00  0.0000E+00  0.0000E+00

The first line in the file indicates the units used, and the second line is a comment line indicating the file content. The next line indicates the load case name for the applied loads that follow. All loads are reported in the part coordinate system.

If there are nodal loads in the structure, they are next. The format of the nodal loads starts with the node name, followed by the forces and moments acting at the node: FX, FY, FZ, MX, MY, MZ. The nodal loads are continued for this load case until an ELMAPL command is encountered.

Element loads have three lines per element. The first line begins with ELMAPL followed by the element name, the class name, the begin and end nodes, and the begin and end distance from the end of the beam over which the load acts. If the begin and end distances are equal then the load is concentrated. The next two lines define the load distribution. For concentrated loads, the two lines are the same and each one define the total load; i.e. one of these lines should be ignored. For distributed loads, the first line defines the load intensity at the beginning distance from the start of the beam and the second line at the end distance. There are six numbers on each line corresponding to force intensities in the X, Y, and Z directions and moment intensities in X, Y, and Z directions. These loads are trapezoidally distributed loads defined by the intensity at each end and the portion of the beam over which it acts, as shown in Figure 30.

Normally, there will be more than one ELMAPL command for each element. These come from a variety of sources, and there is no way to ascertain their origin. The ELMAPL commands are repeated for all the elements in the model that have load for this load case. The sequence of load case name, nodal loads and ELMAPL commands is then repeated for each load case specified.