Irregularity Check Parameter

 

 

 

To select calculation method for story irregularity check

 

 

 

From the Main Menu select Results > Result Tables > Story > Irregularity Check Parameter

 

Select Result Tables > Story > Irregularity Check Parameters in the Tables tab of the Tree Menu.

 

 

 

 

From Record Activation Dialog, select the load cases/combinations for which Stability Coefficient will be calculated and P-Delta effect will be considered.

 

            13-SCT-1.jpg

Record Activation dialog box

 

Refer to Usage of Table Tool and check the following data:
 


 

0-rectangle.jpg When Modules are not defined

 

 

13-SCT-2.jpg

 

 

Load Case: Unit load case/Combination

 

Story: Story number

 

Height: Story (floor to floor) Height

 

 

1. Vertical Load

 

Sum of all the vertical loads of upper story levels is used for calculating Stability Coefficient.

 

 

2. Story Shear Force

 

Story shear force due to the selected Load Case

 

 

3. Modified Story Drift

 

Modified Story Drift = Story Drift X Response Modification Factor (RMF) X Scale up Factor

 

 

4. Beta(β)

 

β: Design Shear Force/Shear Capacity at a story in question.  If it is not calculated, β=1 is used.

 

 

5. Stability Coefficient(Θ)

 

Stability Coefficient(Θ) = ( Vertical Load X Story Drift) / (Story Shear Force X Height X Cd )

 

 

6. Allowable limit

 

Stability Coefficient(Θ) limited by the standard is printed.

 

Allowable limit = 0.5 / (Beta X Cd ) ≤ 0.25

 

 

7. Remark

 

If Θ is less than 0.1, "OK" is printed.

 

If Θ exceeds 0.1 and is less than the Allowable limit, "P-Delta Req." is printed.

 

If Θ exceeds the Allowable limit, "Redesign" is printed.

 

 

8. P-Delta Incremental Factor(ad)

 

For those stories marked with "P-Delta Req." under Remark, Incremental Factor for P-Delta effect is calculated.

 

 

 

0-rectangle.jpg When Modules are defined

 

The Module column is generated only when the Modules are defined. Stability Coefficients are calculated as per the following Note.

 

Note

Stability Coefficients for the top floors of each Module are not generated.

 

 

13-SCT-3.jpg

 

 

Module: Module name is defined in Define Module

 

Load Case: Unit load case/Combination

 

Story: Story number

 

Height: Story (floor to floor) Height

 

 

1. Vertical Load

 

Sum of all the vertical loads of upper story levels is used for calculating Stability Coefficient.

 

 

2. Story Shear Force

 

Story shear force due to the selected Load Case

 

 

3. Modified Story Drift

 

Modified Story Drift = Story Drift X Response Modification Factor (RMF) X Scale up Factor

 

 

4. Beta(β)

 

β: Design Shear Force/Shear Capacity at a story in question.  If it is not calculated, β=1 is used.

 

 

5. Stability Coefficient(Θ)

 

Stability Coefficient(Θ) = ( Vertical Load X Story Drift) / (Story Shear Force X Height X Cd )

 

 

6. Allowable limit

 

Stability Coefficient(Θ) limited by the standard is printed.

 

Allowable limit = 0.5 / (Beta X Cd ) ≤ 0.25

 

 

7. Remark

 

If Θ is less than 0.1, "OK" is printed.

 

If Θ exceeds 0.1 and is less than the Allowable limit, "P-Delta Req." is printed.

 

If Θ exceeds the Allowable limit, "Redesign" is printed.

 

 

8. P-Delta Incremental Factor(ad)

 

For those stories marked with "P-Delta Req." under Remark, Incremental Factor for P-Delta effect is calculated.

 

 

9. Context Menu

The user provides the data for calculating stability coefficients and P-Delta incremental factors.  These are required values for generating the table.  When Table is invoked, the set Story Drift Parameters window is executed first.

 

 

  13-SCT-4.jpg

Context Menu (Set Stability Coefficient Parameter)

 

       13-SCT-5.jpg      

Stability Coefficient Parameter dialog box

 

       13-SCT-6.jpg

Modify Beta dialog box

 

 

Deflection Amplification Factor

 

Importance Factor

 

Scale Factor: Cm, Scale-up Factor

 

Vertical Load Combination: Select a vertical loading condition for which P-Delta effect will be considered.

 

Define Beta: Selection of Beta values.  In case of User Define, values for each story can be directly entered.