There are a number of design restraints that must be observed in order to create a disaster-resistant reinforced concrete shell.
Walls must be engineered as shear walls in their in-plane dimensions, and for the out-of-plane bending moments imposed by wind pressures perpendicular to their plane.
Roofs must include a concrete structural component provided by a cast-in-place reinforced slab or well-connected precast concrete planks.
All energy conserving insulation must be of the rigid board type of manufacture.
All insulation boards should contain built-in web reinforcement to assure positive connection of the boards to the concrete walls and to provide for affixing drywall panels or other finish materials.
Structurally calculated reinforcing bars must be used to connect the wall panels to the roof elements. These may be extensions of the vertical bars in the walls bent over into the roof structure.
Wall panels must be tied securely to the floor slabs with engineered reinforcing bar splices meeting requirements of section 12.15.1 of ACI 318 Building Code Requirements. Welded connections, if used for tornado-resistant service, must be carefully designed by a licensed structural engineer and performed under careful inspection.
Floor slabs, whether on grade or suspended must be structurally reinforced so that they will provide competent diaphragms.
If using precast concrete elements, connections between precast concrete elements are made with monolithic reinforced concrete, engineered in accordance with ACI Report 550.1R-09 "Guide to Emulating Cast-In-Place Detailing for Seismic Design of Precast Concrete Structures" as reported by Joint-ACI-ASCE Committee 550.