EP0594151A1

EP0594151A1 - Method and device for erecting long spanning girders, particularly on viaducts

Info

Publication number: EP0594151A1
Application number: EP93116976A
Authority: EP
Inventors: Giorgio Zuccolo Arrigoni
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-10-21
Filing date: 1993-10-20
Publication date: 1994-04-27
Also published as: ITVE920045A0; IT1261966B; ITVE920045A1

Abstract

The method for the erection of a long girder comprises the steps of

placing a front runway beam (1) on the top of the front pier (3);
placing a rear runway beam (2) on the front extremity of the girder (4) previously erected;
lifting the girder (4') by means of lifting devices fixed to cantilevers (13, 14) provided at the extremities of the girder (4') to be lifted;
translating the girder (4') horizontally and transversely to the longitudinal direction of the girder into a position above the piers (3, 3').

Description

The present invention relates to a device for the erection of prefabricated girders,particularly on viaducts.
Methods and devices for the erection of girders are known.
These methods however proved not to be not properly workable for the erection of long girders,spanning over 150 m.
In fact the well-known solution of using launching trusses,very effective with smaller girders,is pratically not usable since devices long twice the girder to be launched have to be adopted. On the other and, launching trusses can't be used where the viaduct layout has small radius curvatury.
The effectiveness of another erection procedure,named self-launching method,is strongly reduced on the sea viaducts,because auxiliary piers cannot be made;the very high forces that arise require suitable strenghtening or temporary steel stays.
Another method in which sections are built in situ has the drawback to be very time consuming because,since there are a lot of segments,several weldings have to be performed;each welding requiring many working days to be carried out.
Another method that requires the use of floating cranes has the shortcoming to be very expensive,if compared to the present invention.
The aim of the present invention is to avoid the shortcomings of the methods and devices of the known tecniques, carring out a device that enables the erection of long girders rapidly and economically.
In accordance with the present invention, this object is solved in that a lifting device is employed for the erection of long girders, characterized by the fact of including:

a front runway beam placed on the top of the front pier,
a rear runway beam placed on the front extremity of the girder already placed,
lifting devices hoisting the girder by cantilevers fixed at its extremities,
means for the horizontal translation of the girder,
means of anchoring the runway beams to the pier's top,
means of restraining the runway beams against the forces parallel to the girder axis

Further aspects of the present invention, as well as their various benefits, will become more clear from the subsequent description which refers to the drawing illustrating a preferred embodiment of the invention.
Fig 1 shows in a lateral view a preferred embodiment of the invention in the starting phase of the girder lifting.
Figs. 2,3 and 4 show it in a front,rear,top view respectively.
Fig. 5 shows it in a lateral view alter having finished the lifting phase.
Fig. 6 shows it in a top view.
Fig. 7 shows it in a rear view during the translation of the girder.
Fig. 8 shows it in a top view.
Fig. 9 shows it in a lateral view at the end of the positioning of the girder
Fig. 10 shows it in a top view.
Fig. 11 shows it during the displacement of the front runway beam to start a subsequent phase of the cycle.
Fig. 12 shows the detail of the small movable gantry crane resting on the front runway beam during the lifting phase of the girder.
Fig. 13 shows it in a subsequent phase to allow the translation of the girder.
Fig. 14 shows the detail of the small movable gantry crane resting on the rear runway beam.
As can be seen in the drawings, a preferred lifting device to be employed in the inventive method comprises at least one front runway beam 1 placed on the top of the front pier 3 and one rear runway beam 2 put on the front extremity of the girder already placed 4,resting on the rear pier 3'. In this description the terms front and rear are referred to the direction of advancement in the erection phases.
Both runway beams 1 and 2 are made of steel; they are composed of a central part 5 on the pier 3 supporting the girder 4 and two overhanging parts 6,7; the top surface of the runway beams is partially covered by stainless steel in proximity to the track rails (not rapresented in the drawings) for the sliding of the travelling crane 12,12'.
The front beam 1 has a slighter structure than the rear beam 2 and it is provided with a "seat" 8 for the passage of the cantilever 13, and in this seat there is a moveable drawer 9.
The rear beam 2 has a substantially square transversal cross section in order to support the torsional moments due to the cantilevered lifting in rispect to its own longitudinal axis.
Each runaway beam 1,2 is provided with anchoring falls 10 that link the overhanging part 7 to the ballast 11;it is also possible to link the anchoring falls 10 to some bars embedded in the pier base.
The invention provides also that the travelling cranes 12 and 12',sliding on the top face of the beam 1 and 2, have a teflon slide at their bottom surface; the rear travelling crane 12' is provided with a guide roller 16 against the runway beam 2 in order to avoid its overturning;these travelling cranes 12,12' are equipped with lifting devices consisting of rope winches or hydraulic jacks that carry out the lifting of the girder.
The erection of the girder, according to the method developed by this invention,takes place in this way:
the travelling cranes 12,12' are displaced,by a rack and pinion device,at the extremity of the runway beams in the opposite position of the anchoring falls to the ballast.
In this configuration the travelling crane 12 rests upon the seat 8. The girder 4' to be lifted is transported by a barge 12 just besides the bases of the piers 3,3'.
This girder is provided of cantilevers,one in the front extremity 13 and two 14,not aligned with the front one,in the rear extremity of the girder;in this way the lifting is carried out in an isostatic way and it is always possible to foresee the real forces in each lifting device.
After having hooked the lifting falls (or bars) to the cantilevers 13,14 the girder is lifted till its bottom substantially reaches the top pier 3,3' level.
During the lifting phase (see fig. 12),while the cantilever 13 is raising, the movable drawer 9 is in a back position in order not to hamper the complete elevation of the girder.After having reached the final level (fig 13),while the cantilever is still suspended,the movable drawer 9 is pushed in a front position just under the extremity of the cantilever supporting the girder.In this way the continuity of the runaway is obtained,and thanks to a teflon slide is possible to drag (with a rack and pinion jack,not shown in the drawings) the girder to the final position,the cantilever resting on the runway.
When the girder 4' is aligned to the girder 4 already placed, the front extremity is further lifted;later on welding operations take place connecting the rear extremity to the previous girder.Thanks to this already known method it is possible to decrease the positive bending moments in the middle of the girder.
The invention provides also a stabilizing arm 17 that prevent the overturning of the front runaway beam due to wind forces, out of plumb,possible eccentricities,ecc.
At the end of that phases:

the cantilevers 13,14 are dismantled from the girder,
the front runway beam 1 is transported with a floating crane to next pier,
the rear runway beam 2 is displaced (fig. 11) over the girder already lifted until reaches the front end.

The present invention,as can be easily understood, has a lot of advantages,and in particular:

it can be used without modifing civil works because the bending moment in the pier shafts due to the erection procedures is usually lower than the one due to other foreseen accidental actions.
this method requires only a light strenghtening near the cantilevers of the girder in that,beeing the girder lifted at the extremities,the stresses condition are the same when it is normally supported at the ends.

The invention idea and the particular details of construction have been described and illustrated simply by way of example and it is obvious that these details may also be modified, while the essential characteristics of the invention remain unchanged,without exceeding the scope of the appended claims.

Claims

Method for the erection of a long girder comprising the steps of
- placing a front runway beam (1) on the top of the front pier (3);

- placing a rear runway beam (2) on the front extremity of the girder (4) previously erected;

- lifting the girder (4') by means of lifting devices fixed to cantilevers (13, 14) provided at the extremities of the girder (4') to be lifted;

- translating the girder (4') horizontally and transversely to the longitudinal direction of the girder into a position above the piers (3, 3').
Equipment for the erection of long girders including:
- a front runway beam (1) placed on the top of the front pier (3),

- a rear runway beam (2) placed on the front extremity of the girder already erected (4),

- lifting devices hoisting the girder (4') by means of cantilevers (13, 14) fixed at its extremities,

- devices for the horizontal translation of the girder,

- devices of anchoring (10, 11) the runway beams (1, 2) to the pier top,

- devices of restraining the runway beams against the forces parallel to the girder axis,
each runway beam being provided with a small movable gantry crane (12, 12'), running over the runway beam (1), carrying the lifting devices of the girder.
An equipment according to claim 2,
characterized by the fact that the front runway beam (1) is provided with a "seat" (8) for the passage of cantilever (13), and in this seat there is a movable drawer (9) in order to allow the subsequent sliding of the small travelling crane (12').
An equipment according to claim 2,
characterized by the fact that the runway beams (1, 2) are made of steel; they are composed of a central part (5) on the pier (3) supporting the girder (4) and two overhanging parts (6, 7).
An equipment according to claim 4,
characterized by the fact that the top surface of the runway beams (1, 2) is partially covered by stainless steel in proximity to the track rails for the sliding of the travelling crane (12, 12').
An equipment according to claim 4,
characterized in the fact that each runway beam (1, 2) is provided with anchoring falls (10) that link the overhanging part (7) to the ballast (11).
An equipment according to claim 6,
characterized by the fact that the lower part of the anchoring falls (10) can be fixed to the pier bases.
An equipment according to claim 2,
characterized by the fact that the travelling crane (12') is provided with a guide roller (16) against the runway beam (2) in order to avoid its overturning.
An equipment according to claim 2,
characterized by the fact that the travelling crane (12') is provided with a slide made of teflon at the bottom surface.
An equipment according to claim 2,
characterized by the fact that the horizontal translation means of the girder consist of hydraulic jacks.
An equipment according to claim 2,
characterized by the fact that the transversal crosss section of the runway beam (2) is substantially square.
An equipment according to claim 2,
characterized by the fact that the lifting device consists of rope winches or hydraulic jacks with steel strands.
An equipment according to claim 2,
characterized by the fact that the restraining beam (stabilizing arm) (17) consists in a steel structure that fixes the runway beam (1) to the higher part of the pier shaft.