Adding Diaphragm Stiffness Modifiers

You can assign diaphragm stiffness modifiers to decks.

For example, stiffness modifiers can be used to:

account for cracked properties of concrete decks for different directions and actions (in-plane and out-of-plane) in place of crack factors
provide stiffness only along deck orientation for corrugated decks

In the RAM Modeler, select PropTable > Decking. The Deck/Slab Property Information dialog opens.
Select the tab corresponding to the deck type used.

Select to use stiffness modifiers:

Deck type	Select the following
Composite or Noncomposite Floor System	Check the option to Apply Stiffness Modification Factors.
Concrete Slab System	Select the Stiffness Modifiers option in the Slab Stiffness Multipliers group.

(Optional) For Noncomposite Floor and Concrete Slab Systems, type a Two-way Use angle (measured from the global X-axis) to orient the two-way action.
Type the stiffness modification factors to use for force (f11, f22, and f12) and bending (m11, m22, and m12).
The modification factors f11 and f22 are for flexural and axial behaviors and f12 is for shear behavior. The factors m11, and m22 are out-of-plane bending along edges and m12 is for torsion (twisting moment).
Either:

input additional deck/slab parameters and click Add

or
click Change to update the selected existing deck/slab