Bottom and top of column member forces do not match

Question

I've built a 3 story RAM SS model with steel columns pinned at the base, and concrete piers (modeled as concrete columns) pinned at the top. When running a report on the member forces of each, the loads at the bottom of one do not match with the loads at the top of the other. The axial gravity loads do not match, and the axial and shear lateral loads do not match. The difference is more significant than the columns' self-weight (on the magnitude of 10 - 50 kips). I have a concrete slab-on-grade at the base to provide a diaphragm at the ground level instead of at the foundation level, however, I've detached the nodes to allow lateral loads to be carried by the framing rather than all going into the diaphragm. 
 Some background information on the model (all approximate): 
 Footprint: 200'Lx60'W with bays spread at 20' increments 
 Floor to floor heights: 15'-0" 
 Construction: Steel stick built with non-composite concrete metal deck floors and metal deck, EPDM roof 
 Lateral system: Mix between tension/compression chevron bracing and tension/compression X-bracing 
 RAM Modules used: Modeler, Beam, Column, Frame

Seth Guthrie · Answer

Are we talking about dead loads only (i.e. no live load reduction)? If so, then the loads must have found another load path via a continuous beam or 2-way slab with stiffness to redistribute the loads. (Assuming there are no walls involved). You should be able to confirm through member forces output. 
You may want to upload your model using the Secure File Upload process link below left if that's not the answer.

Seth Guthrie · Answer

I ran your file with the latest version, 15.01. At level Interior FDN there is a 5" thick solid concrete slab that is continuous and thus able to redistribute vertical column loads somewhat. It also has self-weight turned on (in addition to the column self-weight which you mentioned), let's consider the lateral column at D-1. At the bottom story the axial loads are: 
 Dead - 109k; 
 Above that story there is a column with 84k axial load and two braces with 16.6 and 5.3 kips axial load. I did not check the angle of the braces, but if they are around 45 deg then the sum of those is about 96 kips. The extra comes from the slab weight and any potential force transfer through slab shear. 
 Looking at one of the wind loads, say W1 we have -18.6 kips in he column below and above the slab we have -12.45 kips in the column plus -8.7 kips in one brace. That works out to -18.6 kips so the redistribution through the slab is very small. 
 Was there another column you were concerned about? Everything seems to be fine to me.