P-Delta Analysis Control

 

 

 

Enter the load cases and the control parameters for iterations used in the P-Delta analysis of a structure. In order to consider the P-Delta effects in the processes of general static and dynamic analyses, we need to define the load condition to formulate the geometric stiffness matrix. We need to also specify the convergence requirements.

midas Civil permits P-Delta analysis for only the structures consisted of beam and truss elements.

Note
In P-Delta analysis, internal moments along a beam element between the two nodes can be obtained from the relative displacements of internal points to the two nodes multiplied by the axial force. V 6.3.0 now automatically generates internal nodes and finds internal displacements to calculate the P-Delta moments along the beam elements.

 

 

 

 

From the Main Menu select Analysis > Analysis Control > P-Delta .

 

 

 Control Parameters

Number of Iterations
Enter the number of iterations for the P-Delta analysis

Convergence Tolerance
Enter the convergence tolerance.

 

P-Delta Combination

Select the loads that will be applied to determine the geometric stiffness matrix used in the P-Delta analysis. Enter different Load Cases with the corresponding Scale Factors.

Select the dead loads (self-weight, dead load, etc.) generally acting on the structures.

 

To enter a new or additional load case

Enter the Load Case and Scale Factor; then click .

 

To modify the scale factor for a previously entered load case

Select the load case, modify the Scale Factor and click .

 

To delete a previously entered load case

Select the load case to be deleted from the load case list at the bottom of the dialog box and click .

 

P-Delta Analysis and Buckling Analysis may not be used simultaneously. The use of P-Delta Analysis is limited to truss and beam elements.

To delete all the entered data, click .

 

 Revision of Civil 2015 (v1.1)

Q1. Which load cases do I have to add in “P-Delta Combination”? The result of the load combination which doesn’t include vertical load case was changed after performing P-delta analysis.