Running the Static Analysis - CAESAR II - Help

CAESAR II Users Guide (2019 Service Pack 1)

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English
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CAESAR II
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CAESAR II Version
11.0 (2019)

The static analysis performed by CAESAR II follows the regular finite element solution routine. The software combines element stiffnesses to form a global system stiffness matrix. Each basic load case defines a set of loads for the ends of all the elements. These elemental load sets are combined into system load vectors. Using the relationship of force equals stiffness times displacement (F=KX), the software can calculate unknown system deflections and rotations. The known deflections however, may change during the analysis as hanger sizing, nonlinear supports, and friction all affect both the stiffness matrix and load vectors.

CAESAR II uses the root solution from this equation, the system-wide deflections and rotations, with the element stiffnesses to determine the global (X, Y, Z) forces and moments at the end of each element. The software translates these forces and moments into a local coordinate system for the element from which it calculates the code-defined stresses. Forces and moments on anchors, restraints, and fixed displacement points are summed to balance all global forces and moments entering the node. Algebraic combinations of the basic load cases pick up this process where appropriate—at the displacement, force and moment, or stress level.

After the software completes the setup for the solution, it repeats the calculation of the displacements and rotations for each of the basic load cases. During this step, the software displays the Incore Solver dialog box.

Incore Solution Module

This dialog box serves as a monitor of the static analysis. The upper-left portion of the dialog box reflects the job size by listing the number of equations to be solved and the bandwidth of the matrix that holds these equations. Multiplying the number of equations by the bandwidth gives a relative indication of the job size. This area also lists the current load case and the total number of basic load cases the software must analyze and solve. The iteration count, as well as the current case number, shows how much work the software has completed. Load cases with nonlinear restraints can require several solutions or iterations before the software confirms the changing assumptions about the restraint configuration, such as resting or lifting off, active or inactive, and so on.

In the lower-left corner of the Incore Solver dialog box are two bar graphs that indicate where the program is in an individual solution. These bar graphs illustrate the speed of the solution. By checking the data in this first box, you have an idea of how much longer to wait for the results.

The right side of the Incore Solver dialog box also provides information regarding the status of nonlinear restraints and hangers in the job. For example, the software displays messages noting the number of restraints that have yet to converge or any hangers that appear to be taking no load here. You can step through nonlinear restraint status on an individual basis by pressing the F2 through F4 keys.

After the analysis of the system deflections and rotations, the software post-processes the results to calculate the local forces, moments, and stresses for the basic load cases and all results for the algebraic combinations (for example L1-L2). CAESAR II stores the total system results in a file with the suffix _P (for example, TUTOR._P).

The _A (or input file), the _P (or output file), and the OTL (Output Time Link file) are all that are required to archive the static analysis. The remaining scratch files can be deleted without any impact on the completed work.

During this post-processing, the Status frame lists the element for which the forces and stresses are being calculated. After the software calculates the last stresses of an element, the output processor dialog box displays. Use this dialog box to review the graphic and tabular results of the analysis. For more information on interactive processing of output results, see Dynamic Input and Analysis.

Static Output Screen