Cross section forces of beam and truss elements relate to the line that connects the cross section centroids. When a cross section changes, chances are high that also the position of its centroid shifts. In case of elements predominantly loaded by bending moments, such a shift can normally be neglected. In the presence of normal forces however – e.g. when considering columns – changes in the centroid position lead to additional bending moments that may be decisive for a members cross section design.