Civil Engineering Reference
In-Depth Information
17
Fixings and connections
All materials and components in a building have to be fixed in some way, using
either mechanical or chemical means. Mechanical fixings include nails, pins or
staples, screws, bolts and wood or iron plugs. Chemical fixings bond materials
together when set. They can be divided into glues and mortars.
Mechanical fixings
Even though forged iron has been known in Northern Europe since AD 1000,
neither iron nor steel was used as a building material until the industrial revo-
lution. Houses were built in earth, stone, brick and timber. The three first mate-
rials fastened together with mortar, whereas timber components which were to
be lengthened, strengthened or connected were joined together with locking
joints.
A common quality of locking joints is that they reduce the strength of the tim-
ber as little as possible. Certain joints are used to preserve the timber's tensile
and bending strength, others to preserve the compressive strength. Wooden
plugs were an integral part of locking joints, often integrated with the locks, but
their most important role was as fixings for both structure and claddings. Today,
nails and screws in steel are the sole components used for the majority of
mechanical fixings in timber building. Steel bolts are used in buildings with large
structural elements. Fixing products are also made of aluminium, copper, bronze
and stainless steel.
A normal sized timber house will contain about 100-150 kg of nails, screws
and bolts. Steel structures are joined mainly through welding, but bolts can also
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