The Structural Systems oF Tall Buildings - Tall Buildings: Structural Systems and Aerodynamic Form - page 33

Belts and vierendeel frames consist of at least one storey depth horizontal shear
trusses or shear walls that located at least two or more levels throughout the height of
the building as in the case of the Commerzbank Tower (Frankfurt, 1997) ( Figure 3.23 ),
which has 6 mega shear walls connected with vierendeel frames. Mega braces are
multi-storey diagonals that are placed continuously throughout the height of the
building as in the case of the Bank of China Tower (Hong Kong, 1990) ( Figure 3.71 ),
which has 4 composite mega columns connected with both mega braces and belts.
According to the authors, mega column systems, in their function and appearance,
can also be named as “mega frame systems” ( Figure 3.21a ); likewise, in some cases
where there are mega braces supporting the mega columns, being reminiscent of a
three dimensional truss, they can also be named as “space truss systems” as in the
case of the Bank of China Tower (Hong Kong, 1990) ( Figure 3.21b ).
Mega column systems efficiently and economically provide sufficient stiffness to
resist wind and earthquake induced lateral loads in buildings of more than 40 storeys.
Some examples of tall buildings using the mega column system with composite struc-
tural material include:

• the 73-storey, 346 m high Center (Hong Kong, 1998) ( Figure 3.22 ) , which has
12 composite mega columns, of which the largest have square cross-sections of
2.5×2.5 m at the ground floor

Mega
brace

Belt

Vierendeel
frame

Mega
column

(a)

(b)

Figure 3.21

Mega column (mega frame, space truss) system