Abstract:
Thus shear walls are one of the most effective building elements
in resisting lateral forces during earthquake.
By constructing shear walls damages due to effect of lateral forces due
to earthquake and high winds can be minimized. Shear walls construction will
provide larger stiffness to the buildings there by reducing the damage to
structure and its contents.
Shear walls are vertical elements of the horizontal force
resisting system. Shear walls
are constructed to counter the effects of lateral load acting on
a structure. In residential construction, shear walls are straight external
walls that typically form a box which provides all of the lateral support for
the building.When shear walls are designed and constructed properly, and they
will have the strength and stiffness to resist the horizontal forces.
In building construction, a rigid vertical diaphragm capable of
transferring lateral forces from exterior walls, floors, and roofs to the
ground foundation in a direction parallel to their planes. Examples are the
reinforced-concrete wall or vertical truss.
Lateral forces caused by wind, earthquake, and uneven settlement loads, in
addition to the weight of structure and occupants; create powerful twisting
(torsion) forces. These forces can literally tear (shear) a building apart.
Reinforcing a frame by attaching or placing a rigid wall inside it maintains
the shape of the frame and prevents rotation at the joints. Shear walls are
especially important in high-rise buildings subjected to lateral wind and seismic
forces.
assumed paths, enter the walls, and exit at the foundation
FORCES ON SHEAR WALL
Shear walls resist two types of forces: shear forces and uplift
forces. Shear forces are generated in
stationary buildings by accelerations resulting from ground movement and by
external forces like wind and waves. This action creates shear forces
throughout the height of the wall between the top and bottom shear wall
connections.
Uplift forces exist on shear walls because the horizontal forces
are applied to the top of the wall. These uplift forces try to lift up one end
of the wall and push the other end down. In some cases, the uplift force is
large enough to tip the wall over. Uplift forces are greater on tall short
walls and less on low long walls. Bearing walls have less uplift than
non-bearing walls because gravity loads on shear walls help them resist uplift.
Shear walls need hold down devices at each end when the gravity loads cannot
resist all of the uplift. The hold down device then provides the necessary
uplift resistance.
Shear walls must provide the necessary lateral strength to resist
horizontal earthquake forces. When shear walls are strong enough, they will
transfer these horizontal forces to the next element in the load path below
them. These other components in the load path may be other shear walls, floors,
foundation walls, slabs or footings.
Shear walls also provide lateral stiffness to prevent the roof or
floor above from excessive side-sway. When shear walls are stiff enough, they
will prevent floor and roof framing members from moving off their supports.
Also, buildings that are sufficiently stiff will usually suffer less
nonstructural damage.
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