I am not able to generate the moment envelope for my mat. When I click on the Generate Moment Envelope button nothing happens. What should I do ?

This may happen for certain specific shaped mats with irregular boundaries. If it does, here are the steps you need to follow to generate the moment envelope.

Go to the Longitudinal axis setup within the Envelope Generation dialog box. By default the longitudinal axis is set to Along Global X as shown next.

Choose ‘By Specifying coordinates’ option as shown next

Change ‘Starting Z’ and ‘Ending Z’ coordinates to the same non-zero value (this will still keep the longitudinal axis horizontal)

Ensure that you have chosen Use All Load Cases under Select load type as shown below

Click on Generate Moment Envelope. Moment envelope should now be generated

If the Moment Envelope still does not generate, slightly change the value for the Starting Z Or the Ending Z. For example instead of 0.2 as in the example, change it to 0.21 for any one of the values. This should help in Moment Envelope Generation. You may do a few trials to figure out how close you can keep these values to be able to generate the envelope. The closer the values, the straighter is the line defining the longitudinal axis.