Structural Design for Architecture
and therefore behave in a similar way to a
hinge. Rigid joints transmit shear and axial
force and bending moment between elements
and therefore provide a fully fixed connection.
Both types of joint can be made either by
welding or by bolting but are normally made
by a combination of both; rigid joints are more
complex and more expensive to design and to
construct. Examples of both types of joint are
shown in Figs 3.23 and 3.24.
The selection of the joint types and their
disposition in the frame is an important
consideration in the design of a steel structure
The principal factors which are affected by the
joints are the stability of the structure and its
state of statical determinacy.^10 Frames in which
the majority of joints are of the hinge type
(simple frames) are usually statically determin-
ate and are easier and cheaper to design and
construct than those with rigid joints, which
are normally statically indeterminate. Frames
with hinge-type joints are usually unstable in
their basic form and require separate bracing
systems for stability. Rigidly jointed frames,
due to their statical indeterminacy, are more
efficient types of structure and therefore have
more slender elements than hinge-jointed
equivalents; they are also self-bracing.10 The question of statical determinacy versus statical
indeterminacy is an important consideration in struc-
tural design because it affects a number of aspects of
the performance of structures. For a discussion of the
issues involved see Appendix 3 of Macdonald, Structure
and Architecture.Fig. 3.23 Hinge-type joints. The joints illustrated here
are capable of transmitting shear force but not bending
moment and are therefore hinge-type connections. Note
that both welding and bolting are used. Welding is more
efficient in transmitting load but bolting is easier on the
building site. The joints are detailed so that the site-made
part of the connection is made by bolting.Fig. 3.24 Rigid joints. These joints allow
the transmission of both shear force and
bending moment between elements. Note
that they too are executed by a combin-
ation of bolting and welding.74