STRUCTURAL DESIGN FOR ARCHITECTURE

Structural Design for Architecture

Fig. 3.30 Basic plan arrangement for a single-storey steel

framework in which the primary elements are strong

girders based on hot-rolled sections.

Fig. 3.29 Diagonal bracing schemes for single-storey

frameworks with lightweight elements,

(a) Diagonal bracing in both horizontal and vertical planes.

(b) Diagonal bracing in the vertical planes; roof cladding

used as.diaphragm bracing in the horizontal plane.

normally used. A wide range of element types

can be adopted depending on the span

involved (Fig. 3.31). For medium spans, univer-

sal or castellated beams are feasible for the

principal elements and if the portal frame

configuration is adopted a very wide span range

is possible with these (15 m to 60 m). Lattice

girders of various geometries, including plane

and space trusses, in which the individual sub-

elements have hot-rolled sections (rectangular

or circular hollow sections, angles, channels,

etc.), are also used over a wide range of spans.

The spacing of the primary elements must

usually be restricted to a maximum of around

6 m to 8 m, regardless of the primary span, so

that the secondary elements are not excessively

large. As in the case of frames with closely

78 spaced primary elements, a wide range of

Fig. 3.31 Typical examples of primary elements in hot-

rolled steelwork.

Portal frame

Parallel chord truss

Pitched truss

Direction span

of cladding

1.5-4.0 m

Mainframe

Secondary structure or purlin

4.0-6.0 m

15-60m