How are axial forces determined in moment frames in RAM Frame? I have a 45' tall structure with a partial mezzanine. The roof is modeled as semirigid and the mezzanine is modeled as rigid. The mezzanine area has moment frames while the full height area has braced frames. In the moment frame, it seems as if the axial loads are determined as the sum of the adjacent beam axial load and the column shears above and below. This works statically until the end when there is a single beam framed into a single story column. I would expect the axial force in the beam to equal the major axis shear in the column, this is not the case. I have turned off p-delta for the purposes of understanding the frame load behavior. I have included images to show overall frame axial loads and major axis shear as well as close ups of the joint I am discussing.
I keep everything connected to the diaphragm and design the beams using a hand check assuming axial compression = (change in frame story shear) * (beam length) / (frame length).
The diaphragm at that level is a rigid diaphragm. What is your recommendation for calculating axial loads in these beams? The axial loads shown seem much higher than I would expect. It seems like axial load is accumulating as you move right instead of axial loads being taken to the foundation through shear in the columns.
If there is a diaphragm there then some of the unbalanced force could be in the diaphragm. Furthermore, if it's a semi-rigid diaphragm then there could be an applied external point load at that location.