Analysis Commands dialog
This dialog is used to specify the method of analysis used as well as any analysis parameters.
Opens when the Analysis Commands tool is selected from the Loading ribbon tab.
An analysis set can be added by click [+]. Each analysis can be set to Active or Inactive; though at least one analysis method should be active.
Click the Edit tool associated with an analysis to make changes to the analysis type and parameters. Click the Delete tool to remove this analysis set.
Configuration Tab
Used to specify the analysis commands for the current analysis.
Load Conditions tab
Used to assign load cases to use with the current analysis set.
Use the filtering tools on the top to select which load cases and combinations are included in the lists. Selecting items from the Available load conditions list and then clicking > will add those conditions to the Selected load conditions list.
P-Delta parameters
Setting | Description |
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No. of iterations |
Specify the number of iterations to be performed. If specified, the program will perform the specified number of iterations whether or not the solution converges. |
Use geometric stiffness (Kg) |
P-Delta analysis including stress stiffening effect of the KG matrix. With this option the global stiffness is adjusted with every iteration. A regular STAAD.Pro P-Delta Analysis performs a first order linear analysis and obtains a set of joint forces from member/plates based on the large P-Delta effect. These forces are added to the original load vector. A second analysis is then performed on this updated load vector (5 to 10 iterations will usually be sufficient). In the new P-Delta KG Analysis, that is, with the Kg option selected, the effect of the axial stress after the first analysis is used to modify the stiffness of the member/plates. A second analysis is then performed using the original load vector. Large & small P-Delta effects are always included (1 or 2 iterations will usually be sufficient). |
Small delta |
Select this option to include both P-small and large Delta effects (recommended), sometimes referred to as P-δ & P-Δ. Leave this box unchecked to only include P-Δ effects (P- Large Delta). Without the Small Delta option (i.e., a default STAAD.Pro P-Delta analysis), STAAD.Pro performs a first order linear analysis and obtains a set of joint forces, from members/plates based on the large P-Delta effect, which are then added to the original load vector. A second analysis is then performed on this updated load vector. With the Small Delta option selected, both the large & small P-Delta effects are included in calculating the end forces, (5 to 10 iterations will usually be sufficient). |
AISC Direct Analysis parameters
Buckling Analysis parameters
Cable Analysis options
Geometric Non-Linear Analysis parameters
Setting | Description | ||||||||
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Load steps |
Specify the number of load steps to be used. Load is applied in stages if entered. One means that all of the load is applied in the first step. |
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Iterations |
Specify the maximum number of iterations to achieve equilibrium in the deformed position to the tolerance specified. |
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Displacement control |
Specify the value of the absolute displacement limit for the first analysis step. If the maximum displacement is greater than this limit, ARC will calculate a new step size for the first step and a new value for Load steps. Value should be in current length units. |
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Tolerance |
For convergence, two successive iteration results must have all displacements the same within this tolerance. Value entered is in current units. |
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Rebuild steps |
Frequency of rebuilds of the tangent K matrix per load step & iteration.
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Include KG matrix |
Select this option to add the geometric stiffness, KG, to the stiffness matrix, K. |
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Target |
Check this option to specify a target displacement value along or about the selected DOF for the monitored Node.
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