WO2012082078A2

WO2012082078A2 - Method and device for incremental launching of concrete bridges outside of theoretical elevation line

Info

Publication number: WO2012082078A2
Application number: PCT/SI2011/000073
Authority: WO
Inventors: Viktor Markelj; Dušan ROŽIČ
Original assignee: Ponting D.O.O.
Priority date: 2010-12-14
Filing date: 2011-12-09
Publication date: 2012-06-21
Also published as: SI23586A; WO2012082078A3

Abstract

Method and device for incremental launching of concrete bridges outside theoretical line solves the above referenced technical problem by new method of providing for vertical alignment of theoretical elevation line using temporary intermediate concrete structure, for purposes of this application known also as concrete stand, According to the method for achieving arbitrary alignment of the bridge structure (1) (usually box cross section) with incremental launching technology one foresees manufacturing of concrete stand 3. The concrete stand 3 is in its essence the stand under webs (vertical walls) 2 of bridge structure 1 of variable thickness, or height. The bridge construction 1 has usually two webs 2 therefore two concrete stands 3 are necessary. The concrete stands 3 are of approximately equal width as webs 2 and are continuous along whole length of the bridge. The third dimension, i.e. height or thickness (d=f(x)) of said concrete stand 3 has variable value in such a way that in its lower part corresponds to theoretical geometrical conditions for launching, and in its upper part corresponds to arbitrary designed alignment according to bridge construction requirements.

Description

METHOD AND DEVICE FOR INCREMENTAL LAUNCHING OF CONCRETE BRIDGES OUTSIDE OF THEORETICAL ELEVATION LINE

Field of invention

Civil engineering; Civil engineering technologies; Incremental launching of bridges Technical problem

Technical problem to be solved by the present patent is limiting of current technology to exact geometry of the axis of the bridge structure or surface onto which the structure is launched. The incremental launching can be used only with bridges with straight axis (R=oo) or constant curving of the axis (R=cons ). When the axis in plan is augmented by change of vertical alignment of this axis one arrives at three dimensional problem which additionally limits possibility of use.

State of the art

The technology known as "incremental launching" (German: »Taktschiebeverfahren«) is method of building bridges where in mechanized shop one manufactures the segments of concrete bridge and (in conjunction with already manufactured segments) launches them into final position of the construction. The building of bridges according to this method has been extremely widespread recently. The reasons are great advantages of this method of building compared to other technologies. In addition to robust and quality construction provided by this method there is also fast and economical building. This method of building was first patented in March of 1967 in former Federal Republic of Germany (DE1237603). In Switzerland similar patent was awarded in 1968 (CG451227) to company Ziiblin, and in France to company CITRA in 1970 (FR1588840).

Due to several advantages of such way of building significant efforts were put into research how to use this technology also in cases when the geometry is not exact and suitable for direct application. Smaller horizontal deviations of road geometry from theoretical requirements can be provided by changed length of cross section cantilevers. However, possibilities are very quickly exhausted as longer cantilevers are usually not achievable. The next step represents the patent of company Walter Bau (Germany) applied for in 1997 as patent for launching of bridges with horizontally curved axis. In particular there is hydraulically motorized workshop which can change angle between previously built and currently built concrete segments. This method was called »matched-cast segments«.

However, one still finds problematic vertical deviation of theoretical line - alignment of the bridge elevation. Alignment of the bridge (road, railway or other type of traffic line) means change of axis in vertical direction. Alignment can be straight in ascent, straight in descent, convex or concave rounding off or of course all transformations between these elements. In special cases of incremental launching of larger spans where during building one uses temporary intermediate supports there needs to be performed so called precamber of alignment due to deformation of construction. In cases of transformation from straight line into curvature, from curvature into opposite curvature in cases of curvature of construction due to precamber the deviations from the theoretical line exceeded capabilities of incremental launching technology know to-date.

In such cases state of the art offers two possibilies:

- variable height of cross section which is not always permissible,

- forced (or induced) launching into desired geometry which is possible only at very large radii of curvature of the alignment. Description of new invention

Method and device for incremental launching of concrete bridges outside theoretical elevation line solves the above referenced technical problem by new method of providing for vertical alignment of theoretical line using temporary intermittent concrete structure, for purposes of this application known also as concrete stand.

According to the method for achieving arbitrary alignment of the bridge structure (1) (usually box cross section) with incremental launching technology one foresees manufacturing of concrete stand 3.

The concrete stand 3 is in its essence the concrete beam structure of variable thickness, or height standing under webs (vertical walls) 2 of bridge structure 1. The bridge structure 1 has usually two webs 2 therefore two concrete stands 3 are necessary. The concrete stands 3 are of approximately equal width as webs 2 and are continuous along whole length of the bridge. The third dimension, i.e. height or thickness (d=f(x)) of said concrete stand 3 has variable value in such a way that in its lower part corresponds to theoretical geometrical conditions for launching, and in its upper part corresponds to arbitrary designed alignment according to bridge construction requirements.

The concrete stand 3 should during the construction period carry all technological influences due to launching, after the launching it should be easily removable from underneath finished main bridge structure. Incremental launching as preferred embodiment which in no way impedes other means of carrying out this invention is usually undertaken using special launching hydraulic device comprised of in principle two parts, i.e. lifting cylinder and pushing cylinder. First, the lifting cylinder lifts the whole structure for some added height, preferably few millimeters whereby the vertical reaction is activated. This reaction through friction (between ribbed steel plate and concrete) provides for ability to perform horizontal force component moving the construction for one working step. This is followed by return stride, i.e. lowering of lifting hydraulic mechanism, resting of construction onto so called brake pad and return of lifting hydraulic into initial position. This working cycle is then repeated. During such working cycle large vertical and horizontal forces are introduced to the construction, these forces transferred through the intermediate concrete beam, said concrete stand 3 subject of this invention.

The concrete stand 3 must transfer vertical and horizontal forces from hydraulic device into the bridge structure 1. During this transfer the concrete stand 3 should not be damaged nor may there be significant slip between the concrete stand 3 and bridge structure 1. The concrete stand 3 slides also over all other columns where the vertical load is of similar magnitude as with hydraulic device while the horizontal component is much lower as this friction is reduced by means of Teflon inserts.

After finished incremental launching of the bridge i.e. in its final position the concrete stand 3 must be removed. The concrete stand 3 and webs 2 are not connected with reinforcing steel, all loads are carried only by means of their rough (either ribbed or some other means of achieving larger friction factor) contact surface. The appropriate level of roughness was in preferred embodiment found by means of tests of frictional load. It was found that so called simple cutting of upper layer of fresh concrete preferably in transverse direction or so called "brooming" of upper concrete layer of the concrete stand 3 suffices, however without smoothing of the concrete.

When the concrete stand 3 with the bridge structure 1 travels over intermediate spans it must not separate from the bridge structure 1. This could happen due to variety of reasons such as cracking, shrinking of the concrete or the vibrations. For that reasons the bolted joints 4 between the bridge structure 1 and the concrete stand 3 are introduced. The concrete stand 3 should due to loads it carries incorporate reinforcing steel preferably from ribbed steel 5.

Method of carrying out the invention

In preferred embodiment for carrying out the invention the manufacturing of the bridge structure is essentially same as in generally used manner, with the exception that the phase of the concrete stand 3 manufacturing is introduced, said concrete stand 3 subject of this invention. On the whole length of the working cycle in the segment workshop on the area of sliding track onto previously laid sliding elements the concrete stand 3 is placed, preferably reinforced. It is performed in approximate width of web 2. The thickness of concrete stand is changing from the minimum thickness needed for suitable reinforcement and is experimentally found to give best results at around 10 cm to necessary thickness as required by desired alignment (vertical deviation of the theoretical elevation line). The strength of poured concrete and the level of reinforcement depends on stresses and deformations related to expected loads in the concrete stand 3.

After finished pouring of the concrete stand 3 in preferred embodiment the surface of the fresh concrete is treated, preferably by essentially gentle strokes of broom of appropriate hardness (so called "brooming"). The concrete is then left to harden for appropriate time, in this mode of carrying out invention until next day (approximately 12 to 24 hours). Then separation layer 6 (emulsion) is introduced, said separation layer to inhibit attaching of concrete of the concrete stand 3 to concrete of the bridge structure 1. If this separation layer 6 is not introduced according to the tests there occurs integration of both concrete layers into same monolithic-like structure which cannot be easily separated after finished launching.

After this step there are usual steps undertaken during construction manufactured by method of incremental launching i.e. formworking, laying of reinforcing steel and cables for lower part of the box, concrete pouring of the lower part and similar building of the upper part. After hardening of the concrete and tensioning of longitudinal cables the bridge structure 1 along with the concrete stand 3 is ready for incremental launching of current work cycle. After the pushing the working cycle is repeated.

After finished launching the final bearings for bridge structure 1 are installed. Then the concrete stand 3 is removed by breaking up the concrete stand 3 and removal of bolt joints 4. If the bolt joints 4 are performed all the way to the lower surface of the concrete stand 3 larger pieces can be removed with less or even without breaking up of the concrete.

The part of this patent applications are also figures, representing: Figure 1 Cross section of the bridge comprising bridge structure 1, web 2, concrete stand 3, height "h".

Figure 2 Partial longitudinal section of the bridge comprising bridge structure 1 , web 2, concrete stand 3, height "h", thickness of the concrete stand 3 depending on alignment d=f(x), geometrical axis x, geometrical axis y.

Figure 3 The detail comprising bridge structure 1, web 2, concrete stand 3, height "h", thickness of the concrete stand 3 depending on alignment "d=f(x)", bolt joint 4, reinforcing steel 5, separation layer 6.

Figure 4 Three dimensional display of bridge part with concrete stand comprising bridge structure 1, web 2, concrete stand 3, height "h", length of segment "Δχ", initial height on segment "yl", final height on segment "y2".

In relation to the figures it should be stressed that they represent the concrete stand 3 and its connection to bridge structure 1 over webs 2. One can see different thicknesses yl and y2 at separate longitudinal parts of the structure, on segment Δχ. The expression d=f(x) is used in mathematically allowable was to show that the thickness of the concrete stand (3) is depending on longitudinal position (and thus required alignment or vertical deviation of theoretical line) along bridge structure 1.

Claims

PATENT CLAIMS

1. Method for incremental launching of concrete bridges outside theoretical elevation line, characterized in that it comprised steps for manufacturing of concrete stand (3) of thickness (d) related to and variable depending on longitudinal position x (i.e. d=f(x)) under webs (2) and launching of bridge structure (1) with the concrete stand (3) or plurality thereof under the webs (2).

2. Method according to claim 1, characterized in that on the top of the concrete stand (3) the surface is made rough preferably by "brooming" or cutting of concrete preferably in transversal direction.

3. Method according to claim 1, characterized in that on the top of the concrete separation layer (6) is applied preferably by means of applying of emulsion, said separation layer (6) simplifying separation of the concrete stand (3) from bridge structure (1).

4. Method according to claim 1, characterized in that the concrete stand (3) and^: the web (2) are connected by means of bolt joint (4) or plurality thereof.

5. Device for incremental launching of concrete bridges outside theoretical elevation line, characterized in that it comprises concrete stand (3) of thickness (d) related to and variable depending on longitudinal position x under webs (2).

6. Device according to claim 5, characterized in that it comprises the surface of the concrete stand (3) made rough by brooming or cutting and separation layer (6) preferably made by applying emulsion.

7. Device according to claim 5 or claim 6, characterized in that it comprises bolt joint (4) or plurality thereof between the concrete stand (3) and the web (2).