Answer:
Although the implemented tool for generating loads may seem simple at first glance, the approach used in the background is quite complex.In order to be able to convert linearly varying surface loads into linearly variable member loads, the option for the correction of the generated loads "According to Moment Equilibrium of Total Loads and Generated Member Loads" is preset in the detail settings.
If, for example, a rectangular cell is present, but there are only three edge members, the load must be distributed so that the resulting moment from the member loads with the respective lever arms to the center of gravity of the cell is zero.
As a result, negative values are determined in the corners when the loading is positive.
If this effect is not desired, the correction of the generated load can be deactivated or set to "None". For this, see the manual, Chapter 11.8.
