Reduced Stiffness
The Specification mandates reduction of both flexural and axial stiffness of steel members. This should be carried out for all lateral members that provide lateral stiffness to structure.
The report first checks if all members are pinned or not. If this is the case, it is not necessary to reduce the flexural stiffnesses and this is indicated in the report.
If the option to reduce the stiffnesses was not selected in RAM Frame Analysis mode, an error message is given.
| Setting | Description |
|---|---|
| Flexural Stiffness |
The program calculates τb based on αPr / Py for all load combinations for all members contributing lateral stiffness (members with pinned ends or with no moments at their ends are skipped). The smallest value of τb is determined and reported, as well as the number of members with τb less than 1.0. The member with the smallest τ b is indicated in the report. Note that τb value used in analysis is defined by the engineer in Criteria – General in RAM Frame Analysis mode. The value used in analysis is compared to smallest calculated value of τb , and validity of the value used is reported. |
| Axial Stiffness | If the option to include the reduction to the axial stiffness is not selected, an error message is given. |