📄 MasterFrame Pro - Shear Wall Modeling
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MasterFrame Pro - Shear Wall Modeling

Technical Note


Title:               Shear Wall Modelling in MasterFrame
Date:              16/10/2003
Versions:      2002.05+
Program:      MasterFrame 

 

The effects of shear walls can be included in MasterFrame, primarily for the purposes of assessing the frame lateral stability.  The shear walls can be included in the MasterFrame model by generating vertical centre line elements of each wall.  

 

The proposed method also models the torsional stiffness of the core based on the summation of the torsional stiffness of the individual shear walls.  This assessment is accurate where the shear core forms an open section such as a ‘C’ shape. However, for a closed shear core section, such as a box shape, the torsional stiffness will be under estimated.

Example:

The structure shown above has a three sided ‘C’ shaped shear core.  The sections of the structure, shown below, represent the arrangement of members necessary to model the shear stiffness of the core.

Vertical members are located at the centre of each shear wall.  The dimension of the member is equal to the thickness and width of the wall.

 

To enable the transfer of forces from the structure to the shear walls, rigid horizontal members are modelled around the perimeter of the shear core.  These rigid members should be given user section properties with very large Ix and Iy second moments of area. These members are also instrumental in representing the combined effect of the shear core system. The rigid link members may also have the 'UT (Rigid Link Member)' member attribute applied, however this has the sole purpose of identify the member as a non-physical member, such that their self weight is automatically ignored, they is not drawn in 3D and are excluded from any BIM operations. The 'UT (Rigid Link Member)' does not affect the member stiffness is any way. The engineer is advised to examine the deflected shape of the model to ensure excessive bending is not observed in the link members relative to the deflection of the shear wall column members.



It is also advisable to fix the bases of the vertical shear wall members.


Note that with the ‘stiff-deck’ effect activated on the floors, all horizontal forces will be transferred automatically to shear core.

Important !  With this method it is essential that the ‘Cases>Torsional Stiffness> Include Shear Deflection’ option is checked. 

Ignoring the effects of shear deflection would be dangerous, leading to unrealistically increased lateral stiffness of the structure.


                                Deflect Shape                                                           Shear Force