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If you are doing seismic analysis, you need to make sure to take rigid beam assumption into account. Increase the beam section to 10ftx10ft, and check the shear in columns. You will find equal shear in storey columns and increasing uniformly from top to bottom corresponding to the applied lateral load. I hope that helps. Make sure you put end offsets of columns to 0 for both ends to properly see shear diagram along the full length. -------- Now comes the question of whats the difference between two. When girders are rigid, moment is computed from sway of columns x height of columns right, but in case of flexible girders, low bending stiffness of girders result in rotation at beam column joint...so additional drift and more moment. When girders are rigid (rigid-diaphragm) lateral force is distributed based on bending stiffness of vertical elements. So equal shear in all columns. When they are flexible, lateral force is distributed based on tributary area, so you see more shear in internal columns as compared to edge columns. 1/3 V in internal columns and 0.5/3 V in edge columns in this example. -------- My understanding about more shear in first storey columns is as follows. Others can correct me. In rigid-frame, shear is resisted by columns by bending in double curvature, this also bends girders in double curvature. Difference of moment of column above and below and the difference of moment of beam framing into this joint from left and right should be zero for equilibrium which is not the case and that is why columns and beams bend in double curvature. First storey columns have more shear because of shear racking. Shear racking is more significant at lower storeys and happen due to the effect mentioned above (double-curvature bending to maintain equilibrium). For example consider this example see the attached image for shear racking. Its like a couple acting as positive force at storey 2 and negative at storey 1, that in turn increases the shear in columns under storey 2 and decreases in columns under storey 1.