Civil Engineering Reference
In-Depth Information
Figure 11:
Technology of realization of superstructure of PE4
It leads to the situation where the level of the neutral axis of the composite section is
next to the shear connection level. To form such a structure the casting of crossbeams is made
together with an additional layer of concrete between constant in-situ slab and prefabricated
slab. The additional concrete layer appears only at the support region and it has variable
height increasing towards support. This way bigger lever arm can be reached for handling
the load of the in situ slab, reinforcement in this layer does not have to be checked for crack
width and no additional step in technology is needed (as this layer is casted as a part of the
crossbeam). Moreover, increased concrete slab thickness in support region leads to better
cooperation between girders due to increased torsional stiffness of slab (“Fig. 11”).
According to principia of the VFT-WIB method, prefabricated composite elements were
initially assumed to be used for construction of superstructures. The complicated geometry
of the bridge led to a very complicated geometry of the prefabricated elements. Especially,
prefabricated girders for spans 1 and 4 differ much, depending on their location in the span.
After many discussions the general contractor decided to build the first line of bridge in its
final position, contrary to the assumed prefabrication of composite elements at ground level
next to the bridge. This way steel elements were supported the same way as it was initially
designed (5 points along the girder) but using high towers typical for in-situ implementations.
It was possible because there was no traffic under the bridge.
Figure 12:
Fabrication of steel structure: a) separation of HEB1000 sections, b) single
T-shape and tandem shape, c) additional coverplate welded at support region
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