U shaped rigid with hollowcore planks

[waldo459]

For a building addition with hollowcore prestress planks it is logical to have 3 shear walls with a U shape. Due to the size of the building, and interior layout, there will be several spans of planks, changing direction, different lengths, etc., and I'm using masonry for interior bearing walls for planks. These interior bearing walls will effect the distribution of shear forces, as they will be connected to the diaphragm. Is it reasonable to assume that the U shape, without the influence of the interior masonry walls, would be a worst case for the exterior walls? This would basically ignore the contribution of the interior walls, although their weight would be included. I would like to avoid putting drag struts in for the interior walls, as this would cut up the planks even more than they already are.