Orthotropic walls
There are typically two ways to define an orthotropic meshed shear wall in Tekla Structural Designer: you either enter material properties manually, or you specify relative stiffness factors. However, note that if working with masonry walls a third option is offered, which is to apply section adjustment factors.
Each of the methods (as described in more
detail below) require you to select the Orthotropic option in the wall
properties. This option actually has two practical uses:
-
It enables different stiffnesses to be set for the two orthogonal (X and Y) directions of walls thus making them orthotropic rather than isotropic (same stiffness in both directions). This can be used to model walls that exhibit orthotropic material properties such as masonry wall panels and cross-laminated timber (CLT) panels.
- For isotropic walls, it also provides a way (as described below) to override the global stiffness modification factor with a modification factor specific to the selected wall only.
Define an orthotropic masonry wall by entering material properties manually
As an alternative to calculating the orthotropic material properties using X and Y factors, the properties can be also set manually if required. The properties take default values based on their state prior to deselecting the checkbox.
To increase the wall panel’s orthotropicity, except adjusting Young’s moduli in the local X and Y directions, respectively, one might consider modifying the in-plane shear modulus, Gxy, as well.
To define properties manually in this way:
- Select the wall to be edited.
-
In the Properties window, open:
- All panels > Analysis & design control - if you want to apply the same orthotropic properties to all panels in a multi-panel wall, or,
- Panel <panel number> > Analysis & design control - if you want to apply the orthotropic properties to a specific panel only.
- Select Orthotropic
- Set Calculation to No calculation
- Enter the required values of Young’s moduli Ex and Ey.
Example: In a particular model in order to achieve highly orthotropic
behavior you might reduce Ey while maintaining the Ex unchanged. To increase the
wall panel’s orthotropicity, one might consider modifying the in-plane shear
modulus, Gxy, as well.
Define an orthotropic masonry wall using X and Y relative stiffness factors
Example: In a particular model in order to achieve highly orthotropic behavior you might enter a Y factor of 0.001 while maintaining the X factor as 1.0.
Define an orthotropic masonry wall using section adjustment factors
Define an orthotropic wall (other than masonry) by entering material properties manually
As an alternative to calculating the orthotropic material properties using X and Y factors, the properties can be also set manually if required. The properties take default values based on their state prior to deselecting the checkbox.
To increase the wall panel’s orthotropicity, except adjusting Young’s moduli in the local X and Y directions, respectively, one might consider modifying the in-plane shear modulus, Gxy, as well.
To define properties manually in this way:
- Select the wall to be edited.
-
In the Properties window, open:
- All panels > Analysis & design control - if you want to apply the same orthotropic properties to all panels in a multi-panel wall, or,
- Panel <panel number> > Analysis & design control - if you want to apply the orthotropic properties to a specific panel only.
- Select Orthotropic
- Clear Calculate properties
- Enter the required values of Young’s moduli Ex and Ey.
Example: In a particular
model in order to achieve highly orthotropic behavior you might reduce Ey while
maintaining the Ex unchanged. To increase the wall panel’s orthotropicity, one might
consider modifying the in-plane shear modulus, Gxy, as well.
Define an orthotropic wall (other than masonry) using X and Y relative stiffness factors
Example: In a particular model in order to achieve highly orthotropic behavior you might enter a Y factor of 0.001 while maintaining the X factor as 1.0.
Override global stiffness modification factor with wall specific factors
Selecting the Orthotropic property provides access to X and Y factors which can be used override the global stiffness modification factor. Although the implication is that you will apply these to make the wall orthotropic there is nothing to prevent you from specifying identical X and Y values. In this case, due to lack of differences between X and Y factors, the wall will be analyzed as an isotropic one. When used in this way, the Orthotropic property can be activated for isotropic walls solely to override the global stiffness modification factor with a wall specific factor.
This is done as follows: