The road/railway bridge
spanning the Paraná river (Brazil) is the major bridge combining road and
railway systems
to be built in Brazil, it consists of a 2,600m long steel
structure (twenty-six 100m spans), besides two 720m and 450m concrete access
viaducts located, respectively, on its left and right sides. The steel
structure is made up of two truss beams, with the railway and roadbed,
respectively, at the upper and lower chords. Four parts in earth, two 600m long
(six spans) and two 700m (seven spans) long, were built on the ground and the
push out to their definitive position. During the
launching phase exerting a
high concentrated force on the bars of the lower chord at places far from the
nodes, in particular, when the extremities of the parts reached a cantilever of
100m. One of the parts was monitored with strain gages. Strains were measured
and stress were evaluated at several points of the structure during the truss
launching phase and then compared to the theoretical values.