[0001] The invention refers to a new method to build viaducts particularly those with big
span and with substantial height on the valley bottom, that is to say for all the
viaducts for which for some time the classic method of lagging and work cementation
has been abandoned. For these kinds of viaducts, already in the sixties, a building
method has had development. Said method provides the realization of the horizontal
carrying structure floor systems by assembling of prefabricated units.
[0002] This also in relation with the development of the pretensioning methods which permit
the subsequent assembling and the solidari zing of separated units afterwards called
"ashlar". In said methods of viaduct building is consequently become of foundamental
importance the development of a method for the moving, the lifting and the positioning
of the prefabricated unit that, in relation, forms the sector advancement.
[0003] All these workings are in the sector called "of launching".
[0004] Principally for these kinds of viaducts are to be considered two different working
methods. A first method refers to a working with a push launching from an end, in
which the ashlars are positioned and solidarized behind of an abutment and then they
are pushed so making move the units on tracks placed on the head of the piers. This
method has the problem that all the piers must already be made, it has the necessity
to have room behind the abutment and it does not permit the scaffolding stopage for
any reasons such for example in relation to possible interferences or for the presence
of obstacles. A second method refers to a positioning with launching truck providing
a span truss equal to one or more spans and consequently much expensive. Also in this
method the bigger problem is given to the necessity to never break off the progressive
advancement of the positioning and to must have big room behind the abutment to mount
and to dismount the truss. As the consequence in said method the working times of
the work are increased both in relation of the slowness of the truck translation velocity
than in relation to the necessity to must mount and to must dismount the truss. The
invented method gives a solution to said disadvantages by a new launching method more
adaptable and more quick and to be actuated by different sequences following described.
1) After to have ended the piers and the same are to the plan height by formwork,
it is positioned the first ashlar from which going on in the working, this positioning
can be made also at the same time on the different piers. 2) On this first scaffolding
unit the rails are put on which will move the apparatus for the ashlar lifting. 3)
On the rail is put the sliding lifting apparatus with all its members, said apparatus
is formed by a sole body and it does not request assembling working on the place.
4) The prefabricated ashlars are brought to the pier base, the sliding apparatus lets
down the horizontal bar, blocks the ashlar, lifts it and places the same making to
transfer it in the position under the already built floor system. When the horizontal
bar has reached the assembling position, the ashlar is further lifted to put it in
height with the part of floor system already realized. 5) During the lifting phase,
so to ensure the stability so avoiding the carrying structure overturning, the same
is fixed to the floor system slab already realized by two stabilizers acting like
tie rod. 6) Placed in building line the ashlar, with the same still supports by the
carrying structure, the joining of the ashlar to the already realized floor system
is actuated, this joining obtained by the pretensioning of two music wire cables.
7) The building so goes on from the end of each pier and it must be actuated in symmetric
way to the pier axis from which the two halfspans start. As a consequence of this,
after to have end the ashlar launching on a halfspan, to not create an overturning-moment
it must be necessary launched the ashlar of the opposed span and all the building
must going on with this sequence. 8) The joining of the whole floor system, formed
by the various halfspans realized as described, is made by means of casts realized
in working by hanging a convention formwork at the two ends of the halfspans. 9) Ending
the building the structure is removed. Making a comparison between the invented method
as described and the previous used cited methods the following advantages are to be
pointed out: a) rooms behind the abutments do not need for the mounting and the dismounting
of the launching truck; b) the sequentiality in the execution of the whole floor system
does not need, this means that part of no adjacent floor system can be realized such
as, in case of different obstacles like presence of electric line, ditches, landslides
or other, it is possible to pass over the building of the halfspans of the pier that
at the moment cannot be built so permitting the no working clocking also in the obstacle
presence, whereas with the current methods a such obstacle brings forcedly to block
the workings; c) the invented method is to be actuated also with span of various width
such it works with indipendent self-moving apparatuses; d) mounting and dismounting
workings are not necessary such the apparatus consists of only three prearranged parts
that are to be moved from a yard to another one; e) the used cargo winch is suitable
for height above the valley bottom of about 80 metres and, in case of bigger height,
in the invented method only the cargo winch must be changed whereasall the other structures
remain the same; f) having more apparatuses it is possible at the same time to work
starting from more piers and also with two shuttling on the same pier so reducing
significantly the working time; g) a big saving on the building costs of the floor
system is obtained such as there are not the big cost of labour for mounting and dismounting
the structure and it is possible to have for the quick working rate a less impact
of the labour on the launching operations. The invented method comprises three parts:
a horizontal carrying structure, a vertical lifting ledger and a hooking beam. The
horizontal carrying structure consists of a level structure 1 formed by two structural
steel work beams with cross bracings 2 on horizontal plane. Said horizontal structure
goes on rails 3 fixed on the scaffolding slab by four motorized wheels 4 with safety
block device 5. The level structure moreover provides feet 6 acting like stabilizers
to be lowered during the lifting phase of the ashlar. The vertical lifting beam consists
of a carrying ledger 7 sliding on jaws 8 to be fixed on the level structure 1 with
motorized cargo winch 9 for lifting the ropes 10 having hanging sheaves 11 with blocks
12. The hooking ledger consists of a carrying beam 13 equipped with hooks and with
two subordinate beams which bring the ashlar with four pins realized with threaded
bars 14.
[0005] For the working after to have mounted the network structure at the pier head the
first three ashlars15, 16 and 17 are placed by a mobile crane. On said ashlars the
rails 3 are placed by fixing the same with passing means, then always with the mobile
crane the horizontal carrying structure with level part 1 is placed. Said part 1 puts
on the rails by its set of wheels 4. Then the vertical lifting beam with the carrying
ledger 7 is placed equipped with cargo winches 9 and ropes 10, laying it on the jaws
8 of the level structure 1. Then the ropes 10 are lowered with hanging by the blocks
12 the carrying beam 13. By the bars 14 the ashlar to be lifted is fixed and it is
lifted acting by the motorized cargo winches 9. At this point the horizontal carrying
structure is moved on the rails 3 till the necessary position.
[0006] Practically said position corresponds to the position of the last ashlar already
jointed. During this hoisting phase the stabilizers 6 of the carrying horizontal structure
are lowered so stabilizing the different parts. The vertical lifting beam with ledger
7, moving itself on jaws 8, is joltingly carried with hooked the ashlar till the position
of the further lifting for the final placing. In this way the ashlar is brought to
the final height to actuate the jointing by prestressing. Ending the jointing the
threaded bars 14 are unhooked, the carrying beam 13 is lowered on the ground and the
vertical lifting beam with ledger 7 is put again in the starting position barycentric
with the set of wheels 4. The stabilizing feet 6 are lifted and the horizontal carrying
structure is moved to the opposed halfspan so to go on with the equal simmetrical
working. The network structure 18 placed on the pier head permits the placing of the
first three ashlars 15, 16 and 17 from which the whole building starts. Said first
three ashlars are launched by a crane. Said network structure 18, after to have mounted
the three ashlars, is dismounted from the pier head with the same crane used for placing
the ashlars 15, 16 and 17.
[0007] Said three starting ashlars form a small room on which the rails 3 bringing the whole
structure are placed. Moreover it is provided, connected to the end of the horizontal
carrying structure with level part 1 a metallic stull 19 with two placing stages so
to control the ashlar positioning and then make its jointing. In this stull the room
is suitable to house the necessary materials, the tensioning jacks and our workers.
Said metallic stull 19 to be moved by a crane to be in help of the working. Said crane
can be the same used for the positioning of the first three ashlars 15, 16 and 17.
The invented method is illustrated in schematic and limitated view in the drawings
of sheets 1, 2, 3, 4, 5, 6 and 7. In sheet 1 fig. 1 is side view of the structures
1 and 7 with the ropes 10 and without the ashlar. In sheet 2 fig. 2 is plant view
of the structures 1 and 7. In sheet 3 fig. 3 is side view in lifting position of the
ashlar. In sheet 4 fig . 4 is transversal section view of an already jointed ashlar
whereas another ashlar is in supporting phase hooked to the hooking beam 13. In sheet
5 fig.5 is perspective view of the horizontal structure with part 1 with on an end
the stull 19 and the vertical structure with ledger 7 in lifting of the ashlar. In
sheet 6 fig. 6 is perspective view of the horizontal carrying structure with part
1 and the vertical structure with ledger 7 with a hooked ashlar during the translation.
In sheet 7 fig. 7 is view in detail of the network structure 18 to be put onto the
pier head for the positioning of the first three ashlars from which the building is
started whereas onto the behind pier is showed the horizontal structure with part
1 during the working phase with the stull 19 connected to its end.
1. Method to build viaducts to be actuated by a horizontal carrying structure, a vertical
lifting ledger and a hooking beam; characterized in that:
- the horizontal carrying structure consists of a level structure (I) formed by two
structural stell work beams with cross bracings (2) on horizontal plane, said structure
goes on rails (3) fixed on the scaffolding slab by four motorized wheels (4) with
safety block device (5), said level structure moreover provides feet (6) acting like
stabilizers to be lowered during the lifting phase of the ashlar;
- the vertical lifting beam consists of a carrying ledger (7) sliding on jaws (8)
to be fixed on the level structure (1) with motorized cargo winch (9) for lifting
the ropes (10) having hanging sheaves (11) with blocks (12);
- the hooking ledger consists of a carrying beam (13) equipped with hooks and with
two subordinate beams which bring the ashlar with four pins realized with threaded
bars (14);
- for the working after to have mounted the network structure at the pier head the
first three ashlars (15, 16 and 17) are placed by a mobile crane, on said ashlars
the rails (3) are placed by fixing the same with passing means then always with the
mobile crane the horizontal carrying structure with level part (1) is placed, said
part (1) puts on the rails by its set of wheels (4), then the vertical lifting beam
with the carrying ledger (7) is placed equipped with cargo winches (9) and ropes (10)
laying it on the jaws (8) of the level structure (1), then the ropes (10) are lowered
with hanging by the blocks (12) the carrying beam (13), by the bars (14) the ashlar
to be lifted is fixed and it is lifted acting by the motorized cargo winches (9),
at this point the horizontal carrying structure is moved on the rails (3) till the
necessary position, during this hoisting phase the stabilizers (6) of the carrying
horizontal structure are lowered so stabilizing the different parts, the vertical
lifting beams with ledger (7) moving itself on jaws ( ) is joltingly carried with
hooked the ashlar till the position of the further lifting for the filing placing
in this way the ashlar is brought to the final height to actuate the jointing by prestressing,
ending the jointing the threaded bars (14) are unhooked, the carrying beam (13) is
lowered on the ground in the starting position barycentric with the set of wheels
(4), the stabilizing feet (6) are lifted and the horizontal carrying structure is
moved to the opposed halfspan so to go on with the equal simmetrical working.
2. Method to build viaducts, as per claim 1, characterized in that a network structure
(18) placed on the pier head permits the placing of the first three ashlars (15, 16
and 17) from which the whole building starts, said first three ashlars are launched
by a crane; said network structure (18) after to have mounted the three ashlars is
dismounted from the pier head with the same crane used for placing the ashlars (15,
16 and 17), said three starting ashlars form a small room on which the rails (3) bringing
the whole strcuture are placed.
3. Method to build viaducts, as per claim 1, characterized in that connected to the end
of the horizontal carrying structure with level part (1) a metallic stull (19) with
two placing stages so to control the ashlar positioning and then make its jointing,
in this stull the room is suitable to house the necessary materials, the tensioning
jacks and four workers; said metallic stull (19) to be moved by a crane to be in help
of the working.
