How to apply a circular line load to a mat foundation ?

A couple of methods can be used as outlined below

Method 1

In reality a line load would be spread over a certain area for example the base area of a wall. So calculate the pressure based on the line load and the base area over which it acts. Apply a circular pressure load in the downward direction. This loading would load the entire circular area with the value of the pressure load. Add one more circular pressure load of the same magnitude but this time in the upward direction with the appropriate radius such that the net loading represents a downward pressure loading over an annular region. Circular pressure Load option is available within Load & Factors > Add Load For Mat Foundation.

Method 2

You can add a series of point loads on the mat to represent a circular line load. The challenge here is that you need to know the coordinates of the load points. The point loads can be applied through Load & Factors > Add Load For Mat Foundation > Add a Point Load