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TO BUILD the crossing from the mainland to the Island of Krk
two sea canals had to be overbridged. Tihi Canal between the
mainland and the Island off St. Marko with the
water table of
462 m width, and Burni Canal between the islands of
St. Marko and Krk of 250 m width. The basic designing and construction
execution problems had to be solved by way of overbridging with
greater bridge span. Introducing the arch foundations and
supports into the sea, the span of the concrete
arch structure was brought to 390 m. In ,spite of that. the greatest ,span of the concrete
arch in the world existing up to that time i. e. the bridge arch of
the Gladesville Bridge on the Parramatti near Sidney. was surpassed
by 85 m.
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The arches were made from prefabricated elements with
cantilever application. and they were held from the coast by
the system of temporary steel tie-rods. In order to decrease forces
in these temporary structures which provided the arches with
cantilever support during the construction, they were built in
two or more stages: first, the central part of the box cross
section, and then their lateral ports which after being joined in the apex
became monolithic creating a unity. The execution of the
central part of the box cross section of this big reinforced concrete
arch is original, very brave solution by cantilever method of building,
with concrete assembly elements. Special problems occurred clue to
very strong winds (hurricane storm with the speed of 142 km/h)
which required additional safety measures.
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Besides the method of construction of the arches, the
building of this bridge vas full of other very interesting and original
technological construction procedures:
- foundation for big arch by means of concrete assembly
elements of individual weight of over 600 t;
- manufacture of very slim and specially light piers in sliding
forms;
- manufacture and erection of concrete prestressed girders
for carriageway structure above high and slim piers using a
launching truss;
- manufacture of assembly elements for carriageway concrete
slabs
- anchoring in the rock material with the force of about 10,000
tons which was present in the main tie-rod for arch bracket
support;
- manufacture of two cable cranes with the span of 635 m each.
and a pylon up to 80 m high.
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In the bridge there were incorporated about 3,60
m3 of plain concrete, 20,500 m3 of reinforced concrete, 4,500 tons of
reinforcement and about 130 t of prestress high yield wire.
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On average there used to work about 350 Iabourers on the
bridge
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