Repair and reconstruction of civil structures - Assessment and Refurbishment of Steel Structures - page 184

gonal upper chords and the span of 10.0 m were placed on the bearer chords. The
suspended ceiling, which created by individual plates made of load-bearing grid of
concreting steel mesh and 20 mm cement plaster, protected the steel load-bearing
structure relatively well during fire. The three most damaged bearers and related roof
trusses above the centre of the fire were replaced.
In the proposal for the reconstruction of the bearers it was assumed that both upper
and lower chords of the retained bearers would be completely unloaded, so that these
chords could be reinforced and the connecting rivets of the outer diagonal would be
replaced by high-strength bolts. Due to lack of time, these bearer chords were not
dismantled and so were not reinforced either. During reconstruction the bearer was
supported at the node (Figure 5.64) by a column and tubes of 19.10 mm diameter.
Figure 5.64 Support for the retained
bearer
The internal forces acting on the reconstructed bearer were determined by taking into
account its strength, geometric shape and static schema, as in Figure 5.65. The contact
distance 1.0 m measured from the node was welded because of a shortage of high-
strength bolts. All members of the bearer reconstructed in this way met the relevant
strength requirements (Figure 5.65).