FEMA 453 Design Guidance for Shelters and Safe Rooms

y the shear walls. Existing masonry infill walls may be retrofitted
to supplement existing reinforcement by either grouting cables
within holes cored within the walls or with a spray-on application of
a shotcrete and welded wire fabric or a polyurea debris catch membrane.
Alternatively, hardened interior partitions may easily be
constructed and anchored to existing floor slabs, and lightweight
metal stud walls may be used to retrofit existing buildings.
2.6.5 pc1 and pc2 tilt-up concrete Shearwalls
and precast concrete Frames and
Shearwalls
Tilt-up concrete buildings are one or more stories in height and
have precast concrete perimeter wall panels that are cast on site
and tilted into place (see Figure 2-33). Floor and roof framing
consists of wood joists, glulam beams, steel beams, open web
joists, or precast plank sections. Framing is supported on interior
steel or concrete columns and perimeter concrete bearing walls.
The floors consist of wood sheathing, concrete over form deck,
or composite concrete slabs. Roofs are typically untopped metal
deck, but may contain lightweight concrete fill. Lateral forces are
resisted by the precast concrete perimeter wall panels. Wall panels
may be solid, or have large window and door openings that cause
the panels to behave more as frames than as shear walls. In older
construction, wood framing is attached to the walls with wood ledgers.
Foundations typically consist of concrete spread footings or
deep pile foundations.
2- 2 Structural deSign criteria