Belfast Truss ~ established as one of the earliest forms of
bowstring truss for achieving an efficient and economical roof
construction over large spans. It was first used in the latter part
of the 19th century and early part of the 20th century for
industrial and agricultural buildings in response to the need for
space uninterrupted by walls and columns within production,
assembly and storage areas. A contribution to the name was a
truss design devised by Messrs. D. Anderson and Son, Ltd. of
Belfast, for supporting their patent roofing felt.Lattice location Alternative
45 °
A = purlins at about
1.000m spacing
centre line radius (see calculation)
Spans up to
about 30.000m
A A
Span
8
Span
2
Centre line radius = [(0.5¾span)^2 + (rise)^2 ]...(2¾rise)
Eg. A 16 m span with a rise of 0.125¾span.
Therefore, rise of truss = 0.125¾16 = 2 m.
Centre line radius = [(0.5¾16)^2 + (2)^2 ]...(2¾2)
=68...4 = 17 m.Long Span Roofs