Why are the column reactions in the Lateral loads so small?

In Ram Structural System 14.07 a change was made in the behavior of 2-way slabs under lateral loads. To prevent the slab from coupling lateral walls and columns together the out-of-plane stiffness is ignored in those lateral load cases when the diaphragm is set to rigid. With the out-of-plane stiffness near zero, the unbalanced forces in lateral columns above and below the slab are necessarily tiny.

Solution

In order to have the out of plane stiffness considered under lateral loads the diaphragm at the level being exported to Ram Concept must be set to semi-rigid. 

See Also

RAMSS Two Way Decks

RAM Frame - Criteria - Diaphragms