Defining a Model - CAESAR II - Help

CAESAR II Users Guide

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English
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CAESAR II
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CAESAR II Version
12

Use the CAESAR II default coordinate system (Y-axis vertical) with the following example to define element definitions.

For this model, most of the element definitions are very simple:

  • The first element, 10-20, is defined as 5 ft. in the positive global X direction. This element starts at the model origin.

  • The second element, 20-30, is defined as 5 ft. in the positive global Y direction. This element begins at the end of the first element, because both elements share node 20.

  • The third element, 30-40, is defined as 5 ft. in the negative global Z direction. Note in Figure 8 that the delta dimension for this element is a negative number. This is necessary to define the element in a negative direction.

  • The fourth element, 40-50, runs in both the positive global X and negative global Y directions. This element slopes to the right and down, and is defined with delta dimensions in both the DX and DY fields. These delta dimensions are equal in magnitude; therefore, this element slopes at 45 degrees.

Continuing the model, from node 50, along the same 45-degree slope can be rather tedious, because most often only the overall element length is known, not its components in the global directions. This can be accomplished with the Edit Deltas dialog box by clicking the Browse button next to the DX field. Using this dialog box, you can enter the element length, and the software determines the appropriate components in the global directions, based on the current direction cosines, which default to those of the preceding element.

CAESAR II provides an additional coding tool, for longer runs of pipe with uniform node spacing. Element Break enables you to break an element into equal length segments, given a node number increment.

In the example, the model is defined solely using delta dimensions. By constructing the model in this fashion, it is assumed that the world coordinates of node 10 the first node in the model are at (0., 0., 0.). This assumption is acceptable in all but one instance, when environmental loads are applied to the model. In this instance, the elevation of the model is critical to the determination of the environmental loads, and therefore must be specified. You can specify the starting node of the model using View/Set Coordinates , and all nodal coordinates display as absolute coordinates. The relative geometry of the model does not change based on specification of the global coordinates of the starting node.

After a model has been defined, there are a number of operations that can be performed on the entire system, or on any section of the system. These operations include:

  • Translating the model by specifying the global coordinates of the starting node of the model. If the model consists of disconnected segments, CAESAR II requests the coordinates of the starting node of each segment.

  • Rotating the model by using the List processor or by clicking List Input . The List processor presents the model in a grid.

    Options in this processor allow you to rotate the model about any of the three global axes, or a specified amount. For example, if the model is rotated a negative -90 degrees about the global Y-axis, the result is as shown in the following illustration.

  • Duplicating the model by using the List processor. The entire model, or any sub-section of the model, can be duplicated.