Analysis Settings
Analysis Settings
The Analysis Settings page and its subpages allow you to adjust the options applied to the different analyses:
 In the current project  when accessed from the Analysis Settings dialog on the Analyze tab.
 In new projects  when accessed from the Settings dialog on the Home tab.
1st order nonlinear settings
Button, command, or option  Description 

Maximum number of iterations 
The number of iterations to perform. Default = 100. 
Tolerance 
At the end of each iteration, values are checked against the previous iteration results. If the difference is less than the tolerance determined here, the result is converged, and the analysis is complete. Default = 0.0001. 
Relative 
Default: ON. 
Relaxation Factors 
Relaxation factors control an amount of nominal compression tensiononly braces can undergo while remaining active during analysis iteration. This improves convergence for rare problematic models/ loading situations in which otherwise most or all braces may experience compression and become inactive, causing instability and preventing solution. When converged tensiononly braces will still have only either zero or tension force. The process is entirely automatic by default and it is anticipated the factors will not require manual editing for most circumstances.
If the model still fails to converge when using relaxation factors, expanding the allowable range (by changing the above minimum and maximum values) may produce convergence. Note:
Relaxation factors are not activated by default, as it is anticipated they will not be required for the majority of models. In addition, since the solution process is necessarily more complex, their use can increase the analysis time to a degree. 
2nd order nonlinear settings
Button, command, or option  Description 

Maximum number of iterations 
The number of iterations to perform. Default = 100. 
Tolerance 
At the end of each iteration, values are checked against the previous iteration results. If the difference is less than the tolerance determined here, the result is converged, and the analysis is complete. Default = 0.0001. 
Relative 
Default: ON. 
Relaxation Factors 
Relaxation factors control an amount of nominal compression tensiononly braces can undergo while remaining active during analysis iteration. This improves convergence for rare problematic models/ loading situations in which otherwise most or all braces may experience compression and become inactive, causing instability and preventing solution. When converged tensiononly braces will still have only either zero or tension force. The process is entirely automatic by default and it is anticipated the factors will not require manual editing for most circumstances.
If the model still fails to converge when using relaxation factors, expanding the allowable range (by changing the above minimum and maximum values) may produce convergence. Note:
Relaxation factors are not activated by default, as it is anticipated they will not be required for the majority of models. In addition, since the solution process is necessarily more complex, their use can increase the analysis time to a degree. 
1st order modal settings
Button, command, or option  Description 

Extraction Method 
Allows you to select the appropriate extraction method for your model. The options are:

Mass Model 
Allows you to select how the mass model of the analysis is displayed. The options are:

Mass reporting  For users that wish to determine a center of mass for each floor, the Simple mass option is available to simplify the calculation. A single value of mass for each node is listed in the Tabular Data for both the "Active Masses by Node" & "Total Masses by Node" view types. The simple mass is calculated by averaging the mass values in the active directions. Note: It is recommended that the simple mass option is used only when the lumped mass model is used.

Stopping Criteria 
Stopping criteria prevent analysis continuing forever. If either of the criteria (Maximum number of modes or Stopping Frequency) are met, the analysis will not look for any more modes. 
Modes 
Allows you to select one of the following options:

Jacobi 
Allows you to adjust the following settings:

Subspace 
Allows you to adjust the following settings:

FEAST 
Allows you to adjust the following settings:

2nd order buckling settings
Button, command, or option  Description 

Maximum number of iterations 
The number of iterations to perform. Default = 1000. 
Tolerance 
At the end of each iteration, values are checked against the previous iteration results. If the difference is less than the tolerance determined here, the result is converged, and the analysis is complete. Default = 0.00001. 
Maximum number of sweeps 
A sweep is a transformation of every offdiagonal in the global matrices. The option allows you to set the maximum number of sweeps allowed. Default = 50. 
Sweep tolerance 
At the end of each sweep, values are checked against the previous sweeps results. If the difference is less than the tolerance determined here the result is converged, and the analysis is complete. Default = 1.0E12. 
Total number of modes 
Allows you to specify the total number of modes required. Default = 10. 
Show negative buckling factors 
Default = OFF. 
Extraction Method 
Allows you to select the appropriate extraction method for your model. The options are:

1st order seismic settings
Button, command, or option  Description 

Extraction Method 
Allows you to select the appropriate extraction method for your model. The options are:

Mass Model 
Allows you to select how the mass model of the analysis is displayed. The options are:

Mass reporting  For users that wish to determine a center of mass for each floor, the Simple mass option is available to simplify the calculation. A single value of mass for each node is listed in the Tabular Data for both the "Active Masses by Node" & "Total Masses by Node" view types. The simple mass is calculated by averaging the mass values in the active directions. Note: It is recommended that the simple mass option is used only when the lumped mass model is used.

Stopping Criteria 
Stopping criteria prevent analysis continuing forever. If either of the criteria (Maximum number of modes or Stopping Frequency) are met, the analysis will not look for any more modes. 
Modes 
Allows you to modify the following options:
Note:
The options in Stopping Criteria overrule both the number of modes and mass percentage. 
Jacobi 
Allows you to adjust the following settings:

Subspace 
Allows you to adjust the following settings:

FEAST 
Allows you to adjust the following settings:

Modal Combination Method 
To determine the representative maximum response of interest for a load case, the relevant values for each relevant mode are combined by using the modal combination method specified here. Note that once modes have been combined, the relative signs are lost. The options are:

Iterative cracked section analysis settings
Button, command, or option  Description 

Global Convergence Criteria 
Allows you to modify the following options:
Tip:
To resolve global convergence failures:

Local Convergence Criteria 
Allows you to modify the following options:
Tip:
To resolve local convergence failures:

Modification factors
 E: Young's modulus
 G: Shear modulus
 I_{torsion}: Section inertia about local X
 I_{major}: Section inertia about local Y
 I_{minor } Section inertia about local Z
 Area: Section area in compression or tension
 A_{parallel to minor}: Section shear area in local Y
 A_{parallel to major}  Section shear area in local Z
 t: shell thickness (applicable to concrete only)
The factors also vary according to the member types, (and in the case of concrete members whether they are cracked or not).
For concrete members in particular, design codes can require that analysis stiffness adjustment factors are applied since the appropriate properties to use in analysis are load and time dependent.
For various other investigations it is also possible that you will want to apply an adjustment to material properties. One suggested example is the assessment of structures subject to corrosion. Another classic requirement in this regard relates to torsion, it is common engineering practice to assume that if it will work without assuming any torsional strength, then torsion can be ignored.
Although default modification factors for each material are provided in the settings sets to reflect the design code being worked to, you should check that these are appropriate for your particular analysis model.
If you make changes to any of the modification factors, analysis must be repeated.
Meshing settings
The meshing options can be adjusted in order to finetune the meshes that are produced in slabs and walls. The default settings are generally appropriate, but they could potentially be adjusted if 2D element quality errors are being created during validation.
Composite steel beams settings
Button, command, or option  Description 

Inertia used for loading analysis list 
Allows you to specify the inertia to be used in the global analysis of the model for a composite steel beam:
Note:
The inertia has different effects on different head codes:
