1 September 1999
typically more flexible than shear wall buildings, and their design is often controlled by drift
d. Building Type 4 - Steel Braced Frame. Steel braced frame buildings are similar in
construction to steel moment frame buildings except lateral resistance is provided by bracing
rather than beam to column moment connections.
e. Building Type 5 - Steel Light Frame. Steel light frame buildings are typically pre-
engineered and prefabricated with rigid frames in the transverse orthogonal direction. The
roofs and walls usually consist of lightweight metal panels. The frames are often designed for
maximum efficiency, often with tapered beam and column sections built up of light plates. The
frames are built in segments and assembled in the field with bolted joints. Lateral loads in the
transverse direction are resisted by the rigid frames with loads distributed to them by the roof
and wall panels. Lateral loads in the longitudinal direction are resisted by steel strap or rod
bracing, or by shear panels located in the roof and walls.
f. Building Type 6 - Steel Frame with Concrete Shear Walls. These buildings are of typical
steel frame construction with lateral loads resisted by cast-in-place reinforced concrete shear
walls. The steel frame is designed for vertical loads only. The shear walls may also serve as
bearing walls carrying vertical loads that would otherwise be carried by steel columns. The
steel frames may provide a secondary lateral force resisting system if the steel columns and
beams are rigidly connected as in Building Type 3. This combined system is termed a "dual"
system in which the steel moment frames are designed to work together with the concrete
shear walls with load sharing dependent on the stiffness of the two systems. In this case, the
walls would be evaluated as concrete shear walls, and the frames would be evaluated as steel
g. Building Type 7 - Steel Frame with Infill Shear Walls. In this older type of construction,
some of which still remains, solidly infilled masonry panels act as a diagonal strut between
moment frames. This type of construction is not recommended, because if the infill walls do
not fully engage the frame members (i.e., lie in the same plane), diagonal compression strut
action will not develop.
h. Building Type 8 - Concrete Moment Frame. These buildings are similar to steel
moment frame buildings except the frames are of reinforced concrete construction. In high
seismic areas the concrete frames have large quantities of longitudinal and transverse
reinforcing steel, with closely spaced transverse steel (spiral reinforcement and stirrups)
required to confine the concrete and produce a ductile response to earthquake ground motion.
i. Building Type 9 - Concrete Shear Walls. The vertical components of the lateral-force
resisting system in these buildings are concrete shear walls that are usually bearing walls.
Buildings in which the shear wall area is relatively large with respect to the floor area, there
often is no need to provide boundary elements to handle the large compressive strains that
can occur in the wall extremities. Buildings with limited shear wall area will require shear wall
boundary elements in accordance with ACI 318.
j. Building Type 10 - Concrete Frame with Infill Shear Walls. These buildings are similar
to Type 7 buildings except that the frame is of reinforced concrete. The capacity of this system