Walls - Design of Reinforced Concrete - page 559

lateral forces be coming from the other direction, they would be resisted by the shear
walls C and D.
The walls must be sufficiently strong so as to limit deflections to reasonable values.
In addition, they must be so designed that tensile stresses caused by the lateral forces do
not exceed the compression stresses caused by the building weight above.
Shear walls are commonly used for buildings with flat-plate floor slabs. In fact, this
combination of slabs and walls is the most common type of construction used today for
tall apartment buildings and other residential buildings.
Shear walls span the entire vertical distances between floors. If the walls are care-
fully and symmetrically placed in plan, they will efficiently resist both vertical and
lateral loads and do so without interfering substantially with the architectural require-
ments. Reinforced concrete buildings of up to 70 stories have been constructed with
shear walls. In the horizontal direction full shear walls may be used—that is, they will
run for the full panel or bay lengths. When forces are smaller, they need only run for
partial bay lengths.
Shear walls may be used to resist lateral forces only, or they may be used in addition
as bearing walls. Furthermore they may be used to enclose elevators, stairwells, and per-
haps restrooms, as shown in Figure 18.3. These box-type structures shown are very satis-
factory for resisting horizontal forces.
Another possible arrangement of shear walls is shown in Figure 18.4. Although shear
walls may be also be needed in the long direction of this building, they are not included in
this figure.
On most occasions it is not possible to use shear walls without some openings in
them for doors, windows, and penetrations for mechanical services. Usually it is possible,
however, with careful planning to place these openings so they do not seriously affect
stiffnesses or stresses in the walls. When the openings are small, their overall effect is
minor but this is not the case when large openings are present.
Usually the openings (windows, doors, etc.) are placed in vertical and symmetrical
rows in the walls throughout the height of the structure. The wall sections on the sides
columns
Figure 18.3 Shear walls around elevators and stairwells.