The Structural Systems oF Tall Buildings - Tall Buildings: Structural Systems and Aerodynamic Form - page 26

(a) (b)

Figure 3.13

(a) Shear trusses / shear walls in plan, (b) partially closed cores in plan

a
m

~30m
42.5m

Figure 3.14 Seagram Building, New York, USA, 1958
(photo courtesy of Antony Wood / CTBUH)

systems are not subject to torsion. Otherwise, torsion occurs, and the torsional forces
must also be taken into account. The most effective behaviour against torsion in the
shear trusses and shear walls is ensured by partially closed cores.
Shear-frame systems efficiently and economically provide sufficient stiffness to
resist wind and earthquake induced lateral loads in buildings of more than (as well
as below) 40 storeys. In shear-frame systems, shear trusses and shear walls may be
used together with rigid frame, as in the 38-storey, 157 m high Seagram Building (New
York, 1958) ( Figure 3.14 ), with its composite structural system, designed by Mies van
der Rohe. In the 38-storey Seagram Building, up to the seventeenth floor, reinforced
concrete shear walls, and in the upper storeys steel shear trusses were used (Ali and
Moon, 2007).