Answer:
The reason: Each surface has a local coordinate system (x, y, z) in RFEM. Coordinates x and y lie in the surface; z is perpendicular to the surface.
The top and bottom sides of a surface are determined by the direction of the z-axis. The direction in which the local z-axis points is the bottom side of a surface. Normally, this local z-axis points downwards. Depending on the definition direction of the boundary lines and the order in which the lines were clicked, it may also be possible for the local z-axis to point upwards.
However, this can be corrected very easily. Please display the local surface coordinate systems first. Proceed as follows:
Activate the Display navigator on the left side of the screen. You can do this using the second tab at the bottom of the navigator. Here, you can set all display properties in a tree-shaped structure.
Open the "Model" → "Surfaces" branch and activate the check box next to the "Surface Axis Systems x, y, z" entry.
The bottom reinforcement is on the side of the plate where the z-direction is positive.
To reverse the direction of the local z-axis, right-click the relevant surface and select "Reverse Local Axis System" in the shortcut menu.
