P Delta Analysis tab
Used to direct STAAD.Pro to perform a second order analysis.
Refer to TR.37.2 PDelta Analysis Options for additional information.
Setting  Description  

Number 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) 
PDelta analysis including stress stiffening effect of the KG matrix. With this option the global stiffness is adjusted with every iteration. A regular STAAD.Pro PDelta Analysis performs a first order linear analysis and obtains a set of joint forces from member/plates based on the large PDelta 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 PDelta 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 PDelta effects are always included (1 or 2 iterations will usually be sufficient). 

Small Delta 
Select this option to include both Psmall and large Delta effects (recommended), sometimes referred to as Pδ & PΔ. Leave this box uncheck to only include the "PlargeDelta" effects (PΔ only). Without the Small Delta option (i.e., a default STAAD.Pro PDelta analysis), STAAD.Pro performs a first order linear analysis and obtains a set of joint forces, from members/plates based on the large PDelta 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 PDelta effects are included in calculating the end forces, (5 to 10 iterations will usually be sufficient). 

Print Option  Standard STAAD.Pro analysis print options:
