Civil Engineering Reference
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during construction as the cantilever arms were increased in length. The bridge was
redesigned and a new material, nickel steel, was used in the reconstruction. In 1916,
the suspended span truss fell while being hoisted into place. It was quickly rebuilt
and the Quebec Bridge was opened to railway traffic in 1917 (Figure 1.15c).Another
major cantilever-type bridge was not to be constructed until after 1930. It remains the
longest span cantilever bridge in the world.
Continuous spans were often used for long-span steel railway bridge construction
in Europe but seldom in North America due to the practice of avoiding statically
indeterminate railway bridge structures. The first long-span continuous steel truss
railway bridge was built by the Canadian Pacific Railway over the St. Lawrence
River at Montreal in 1887 ( Figure 1.16). The 408 ft main spans were erected by the
cantilever method without falsework. The Viaur Viaduct, built in 1898, was the first
major steel railway bridge in France. §
FIGURE 1.15a The 1907 Quebec Bridge collapse, Canada. (Carleton University Civil
Engineering Exhibits.)
The original designer was Theodore Cooper. Following the collapse a design was submitted by
H.E. Vautelet, but the redesign of the bridge was carried out by G.H. Duggan under the review of
C.C. Schneider, R. Modjeski, and C.N. Monsarrat.
Alloy nickel steel was first used in 1909 on the Blackwell's Island (now Queensboro) Bridge in
New York. Nickel steel was also used extensively by J.A.L. Waddell for long-span railway bridge
designs. A.N. Talbot conducted tests of nickel steel connections for the Quebec Bridge reconstruction.
These spans were replaced in 1912 due to concern over performance under heavier train loads.
§
This cantilever truss arch bridge is unusual in that it incorporates no suspended span, thereby rendering
the structure statically indeterminate. Many engineers believe that the design was inappropriate for
railroad loading.
 
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