1 September 1999
during major earthquakes is often limited by the shear strength of the columns (non-ductile
response) since once the infill cracks much of the shear is transferred to the columns. For this
reason the use of Type 10 buildings is not recommended for high seismic regions.
k. Building Type 11 - Precast/Tilt-Up Concrete Walls with Lightweight Flexible Diaphragm.
These buildings often have a metal deck or wood roof diaphragms that distributes lateral
forces to precast concrete shear walls. The connections between the diaphragms and walls
and between precast concrete wall elements are extremely important in high seismic regions.
Tilt-up buildings often are more than one story.
l. Building Type 12 - Precast Concrete Frames with Concrete Shear Walls. These
buildings typically have floor and roof diaphragms composed of precast concrete elements with
or without cast-in-place concrete topping slabs. In high seismic regions, cast-in-place concrete
topping slabs are generally used unless diaphragm spans are very small. Precast concrete
girders and columns support the diaphragms. The girders often bear on column corbels.
Closure strips between precast floor elements and beam column joints usually are cast-in-
place concrete. Welded steel inserts often are used to interconnect precast elements. The
capacity of these type buildings to resist lateral loads is dependent on connection strength and
ductility. Buildings with precast frames and concrete shear walls should perform as intended
during major earthquakes if the connections have sufficient strength and displacement
m. Building Type 13 - Reinforced Masonry Bearing Walls with Metal Deck Roof
Diaphragms. These buildings have perimeter bearing walls of reinforced concrete masonry
units (CMU) or reinforced brick construction. The bearing walls are also the vertical elements
of the lateral force resisting system. The roof diaphragm is of metal deck construction with or
without a cast-in-place topping. Floor diaphragms are generally a reinforced concrete slab or
precast concrete slab supported by steel beams or CMU walls. The roof and floor diaphragms
should have sufficient strength and stiffness to transfer lateral loads to the transverse shear
walls without imposing excessive out-of-plane displacements on the longitudinal walls.
n. Building Type 14 - Reinforced Masonry Walls with Precast Concrete Roof Diaphragm.
These buildings are similar to Type 13 buildings except the roof diaphragm is composed of
interconnected precast concrete elements such as planks, or tee beams with or without a cast-
in-place topping. The roof diaphragm is stiffer than the metal deck diaphragm of the Type 13
building and therefore roof diaphragm deflections will generally not impose excessive
displacements on the longitudinal walls. Because of efflorescence problems double wythe
construction with grout fill between wythes is not permitted for military buildings.
o. Building Type 15 - Unreinforced Masonry Bearing Wall Building. These buildings are
similar in construction to Type 13 and Type 14 buildings except the masonry is unreinforced or
has the minimum reinforcement required by code. Unreinforced masonry construction is typical
in the eastern and mid-western United States. The performance of unreinforced masonry
buildings when subjected to earthquake ground motions has often been unsatisfactory. For
this reason Type 15 building construction is not permitted by the Army and Air Force.