Q: Can I define my own yield-line failure mechanism?

Question

I would like to check a yield-line pattern that I have defined myself, can I do this?

Solution

Yes, by following a few simple steps you can specify a user-defined yield-line pattern that the software will use on solve.

To do this:

1. In your model, draw in the postulated yield lines using the 'draw' functionality.
2. Define the slab definition properties that you wish to assign to the problem.
3. Assign this slab definition to the yield-lines that you defined, as well as to the supported edges of the model.
4. Create a second slab definition that is much stronger than the ‘true’ value you defined previously.
5. Assign the strong definition to all the solids in the model.
6. In the Property Editor, select “Nodal Density>Custom” and set the target number to 1. This ensures that no additional nodes are added to the problem and suppresses the generation of additional yield-lines upon solve.
7. Solve the problem.

You should find that the failure pattern is now only permitted to occur along the lines that you have specified. It should, however, be noted that if the failure mechanism does not meet the compatibility requirements, the software may add in additional yield lines between vertices and this will result in a higher adequacy factor being reported (as it will necessitate yielding of the stronger slab material). For example, try modifying the position of one of the end nodes that meets the central cutout in the attached file.