STRUCTURAL DESIGN FOR ARCHITECTURE

Fig. 6.29 Traditional forms of semi-truss such as these

are not fully triangulated and depend on continuity of the

sub-elements through the joints for stability.

20 m). Timber trusses must normally be signifi-

cantly deeper than equivalent steel trusses and

provision must be made for this in the design

of buildings which are to have a primary struc-

ture of timber.

Most one-off trusses are assemblies of

multiple-component elements which are

connected together at multiple lap-joints in

which the fastening components are bolts,

usually with timber connectors (Figs 6.30 and

6.31). The critical factor which determines the

feasibility or otherwise of a proposed arrange-

ment is frequently the design of the joints

(Fig. 6.32). This must be such as to allow suffi-

cient area of overlap between elements to

accommodate the number of connectors

which are required to transmit the load. It is

frequently found advantageous to use low-

grade timber for large trusses because the

Fig. 6.30 Typical joint arrangements for large, one-off

trusses. The fastening elements are bolts which are used in

conjunction with timber connectors.

larger elements which result from this provide

more space for the joints. This also reduces

the slenderness ratios of the compression

208 elements.

Structural Design for Architecture

Three members

Five members

Seven members