STRUCTURAL DESIGN FOR ARCHITECTURE

Fig. 4.51 Plan arrangements for reinforced concrete

beam-column frames.

(a) One-way-span slab spanning between parallel beams.

(b) Two-way-span slab on a grid of beams.

Due to the simplicity of the formwork and

the high level of structural efficiency which is

achieved as a result of the high degree of stat-

ical indeterminacy, two-way-spanning slab

structures of both the plain and the coffered

types provide very economical support systems

for multi-storey buildings in which large wall-

free areas are required. They are particularly

suitable where the imposed load is high and

uniformly distributed but are less suitable

where concentrated loads are high, for

example in buildings in which machinery has

to be housed. They are also unsuitable for

buildings in which the benefits of structural

continuity are limited, either because large

breaks in the continuity of floors occurs (Fig.

2.14) or because the building has a compli-

cated geometry in plan and section (Fig. 4.15).

In such cases a frame structure is normally

required.

4.4.2.4 Frame structures

The distinctive characteristic of a frame is that

it consists of an arrangement of beams and

columns which supports slab floors. There are

two basic types of reinforced concrete frame,

the distinguishing feature being whether the

floor is a one-way-spanning or a two-way-

spanning system (Fig. 4.51).

In the frame with a one-way-spanning floor

the floor-slab spans as a continuous system

Fig. 4.52 Beam-column frame with one-way span slab.

One-way span slabs are normally carried on parallel

arrangements of beams supported by a rectangular column

grid. No beams are provided in the direction of the slab

span.

across a series of beams which are supported

individually on columns. The beams act with

the slab to form flanged T- or L-beams (Figs

4.37 and 4.52). Linking beams, running in the

same direction as the slab, are not normally

provided between the columns because the

slabs themselves provide an adequate struc-

tural connection. The whole structure of

beams, columns and slabs is cast in stages to

138 form a continuous monolithic unit. Typical

Structural Design for Architecture

5m

to

10m

3 m to 6 m