Surface Stiffness Modifications

A surface stiffness modification offers various options to affect the stiffness of surfaces.

'New Surface Stiffness Modification' Dialog Box

Modification Type

Various types are available for selection in the list. The other sections of the dialog box match the modification type.

Selecting Modification Type

Multiplier factors

You can adjust the stiffness in different ways by using "Multiplier factors":

• Total stiffness: All elements of the stiffness matrix are uniformly multiplied by the factor "k."
• Partial stiffnesses, weights, and masses: The elements of the stiffness matrix and the weight can be modified by specific factors.
• Stiffness matrix elements: Each element of the stiffness matrix can be influenced by a factor.

The New Surface Stiffness Modification image shows how the bending and torsional stiffness is reduced to 75%.

Settings

For US and Canadian standards, there are some modification options to apply stiffness factors in compliance with the standards.

ACI 318-19 / CSA A23.3

Settings for ACI

Select the "Component Type" from the list:

• Walls uncracked
• Walls cracked
• Flat plates and flat slabs

The factor k_b for determining the bending and torsional stiffness is set according to the standard.