The Structural Systems oF Tall Buildings - Tall Buildings: Structural Systems and Aerodynamic Form - page 23

3.5 shear wall systems

Shear wall systems are used in reinforced concrete buildings. This system consists of
reinforced concrete shear walls, which can be perforated (with openings) or solid.
Shear wall systems can be thought of as a vertical cantilever rigidly fixed at the base,
and can resist all vertical and lateral loads on a building without columns ( Figure 3.9 ).
Owing to the nature of cantilever behaviour, the inter-storey drift between adjacent
floors is greater in the upper floors than in the other floors. For this reason, in supertall
buildings it is difficult to control the lateral drift at the building top.
Shear wall systems efficiently and economically provide sufficient stiffness to resist
wind and earthquake induced lateral loads in buildings of up to about 35 storeys.

Figure 3.9

Shear wall system

3.6 shear-frame systems

Rigid frame systems economically do not have sufficient resistance against lateral
loads in buildings over 25 storeys because of bending on columns that causes large
deformations. In this case, the total stiffness and so the economical height of the
building can be increased by adding vertical shear trusses (braces) and/or shear walls
to the rigid frame to carry the external shear induced by lateral loads ( Figure 3.10 ).
This interactive system of frames and shear trusses and/or shear walls is called the
“shear-frame system”, and is quite effective against lateral loads ( Figure 3.11 ). In this
context, shear-frame systems can be divided into two types:

• shear trussed frame (braced frame) system ( Figure 3.11a )
• shear walled frame system ( Figure 3.11b ) .