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User Interface

Perform Direct Analysis dialog

Used to instruct STAAD.Pro to perform a direct analysis per AISC 360-05 Appendix 7.This method

accounts for the second order effects resulting from deformation in the structure due to applied loading,imperfections and reduced bending stiffness of members due to the presence of axial load.

This is a non-linear iterative analysis as the stiffness of the members is dependent upon the forcesgenerated by the load. The analysis will iterate, in each step changing the member characteristics until themaximum change in any

 b is less than the Tau tolerance. If the maximum change in any

 b is less than

100x the Tau tolerance and  the maximum change in any displacement degree of freedom is less than the Displacement  tolerance; then the solution has converged for this case.

This analysis method is to be used in conjunction with Direct Analysis definition command. The DefineDirect command should be added prior to instructing the program to perform this type of analysis.

 Additionally, a direct analysis typically requires the definition of Notional Loads.

This feature is available in STAAD.Pro 2007 Build 03 and higher. Refer to AD.2007-03.2.2 in the What's New section for additional information on using this feature.

Opens when:

Commands > Analysis > Perform Direct Analysis… is selected, or

The Analysis/Print | Analysis page is selected.

Refer to Section 5.37.5 of the Technical Reference Manual for additional information.

 Perform Direct Analysis dialog

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Option

Select if the design methodology is Load Resistance and Factor (LRFD) or Allowable Stress(ASD).

Tau

The limit to the change in the  b value in each iteration. If this value is exceeded by any member,

then an additional iteration will be required unless the maximum number of iterations has been

achievedDisplacement

The limit to the change in the maximum displacement in each iteration. If this has beenexceeded, then an additional iteration will be required unless the maximum number of iterationshas been achieved.

Number of Iterations

Specify the maximum number of iterations.

Print Option

Standard STAAD analysis print options. See Perform Analysis dialog.

OK Adds the analysis command to the input file with the selected parameters and/or print options.

Cancel

Closes the dialog without adding a analysis command.

Help

Opens the STAAD.Pro help window.

Reference Materials

Create Reference Load dialog 

Create New Direct Analysis Definition dialog 

Repeat Load tab 

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