e-mosty December 2017 MSS and Formwork Travellers | Page 15

Figure 16: Engano Viaduct cross sections
– initial (right) and final (left)
PROJECTO INICIAL
PROJECTO FINAL
To overcome a larger span, the height of the box
girder was raised from 2.65 m to 3.20 m which didn’t
penalize much the weight of the concrete girder since
the design was optimized to the new geometry –
Figure 16. The final concrete section was only 5%
heavier than the one from the initial design. This
difference was highly compensated by the reduction
of the number of piers.
The heaviest section has now 8.05 m 2 , which
corresponds to a slab weight of 201.3 kN/m. The
layout of the viaduct is curved, with a constant radius
of 1200 m and a constant transversal slope of 3.1 %.
The pre-stressing was designed considering the
execution of the viaduct from abutment E-2 (right side
on Figure 15) to E-1 (left side on Figure 15), an initial
span of 50 m, 9 consecutive spans of 70 m and a last
span of 41 m.
Considering the construction joint always 17.5 m
ahead of the corresponding pier, allowed the MSS
rear support to be placed 16 m ahead of the rear pier
in all spans, which corresponds to 54 m concreting
span (Figure 17).
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Figure 17: Difference for 1/4 and 1/5 of the span joints
4/2017