STRUCTURAL DESIGN FOR ARCHITECTURE

Structural Design for Architecture

Fig. 3.54 Where diaphragm-type vertical-plane bracing is

used it is normally constructed in either masonry or

reinforced concrete. It can consist simply of infill walls in

the steel framework or, as is shown here, it can take the

form of free-standing cores to which the steelwork is

attached. In the latter case the cores are normally

constructed to the full height of the building in advance of

the steelwork being erected. As these cores normally

contain stairs they provide access to all parts of the build-

ing throughout the construction sequence.

An example of a special requirement is the

situation in which the lowest storey of a build-

ing must have a different plan geometry from

upper floors because it contains a radically

different type of accommodation. This can

create the need for a special frame, especially

if, as is often the case, there is a requirement

to reduce the number of columns in the lowest

storey. One way in which this is achieved is by

locating a number of very large girders at first-

floor level so as to transmit the loads from the

columns in the upper storeys to a smaller

number of columns in the ground floor.

Another arrangement which has been used is

the suspended frame (Fig. 3.55). This has the

additional advantage that it reduces the size of

the majority of the vertical elements because

tension elements have a smaller cross-section

than equivalent columns. The adoption of this

type of system therefore increases the usable

floor area per storey.

3.6.3.5 High-rise multi-storey frames

The dominating factor in the design of high-

rise frames is the need to provide sufficient

lateral strength and rigidity to resist wind load

effectively. As in the case of low- and medium-

rise multi-storey buildings, the floor must be

designed to provide effective resistance to

gravitational loads and to act as a horizontal

Fig. 3.55 Suspended frame arrangement. The floors here

are suspended from one or other of two massive trusses

which are supported on a central core. The total volume of

vertical structure is theoretically lower than with the trad-

itional column grid arrangement because the concentration

of the compressive function into one massive central

element allows higher compressive stresses to be used

(because the slenderness of the single compressive element

is relatively low). The structure of the HongkongBank

94 Headquarters (Fig. 1.3) is based on this principle.