EP0666157A1

EP0666157A1 - Multipurpose sleepers fabrication method

Info

Publication number: EP0666157A1
Application number: EP95500002A
Authority: EP
Inventors: Hakan D. V. Kristensson; Luis D. Albajar Molera
Original assignee: ALVISTRANVI SA
Current assignee: ALVI, S.A.
Priority date: 1994-01-11
Filing date: 1995-01-11
Publication date: 1995-08-09
Also published as: ES2116819B1; ES2116819A1

Abstract

Multipurpose sleepers fabrication method which consists in the use of prestressing cable reinforcement, controlling the prestressing force between the sleepers, at the same time they maintain an elevated position while the moulds descend, with this method the ascending forces are suppressed and the displacement of the sleepers are reduced to a minimum along the bedframe. Some compression plates located between the ends of each neighbouring element and some compression members that are applied on these plates maintain the sleepers in position without applying any ascending force.

The reinforcement is formed by prestressing cables of which four of them corresponding to the upper area are of larger diameter than the eight of the lower ones.

Description

INVENTION APPLICATION FIELD

The present invention will be of application in the railway multipurpose sleepers fabrication, with the object of obtaining sleepers that allow the placing of different track gage on them, both exclusively for RENFE gage or INTERNATIONAL gage, without modification of prestressing as an indistinctly multipurpose form for either one or another track gage through the corresponding adoption of the respective anchorings.

STATE OF THE ART

At the present time, there are different methods of sleepers fabrication or elements of prestressing concrete, which are moulded one after the other spaced in separate moulds between each other and among which the reinforcement is extended.
One of the methods more used is the one that corresponds to the Swedish Patent n° 7807242-8 applied by STRANGBETONG, STOCKHOLM on June 26, 1978 and granted on December 4, 1980, in which is claimed a "Method and device for elevating concrete elements, preferably prestressed" and essentially characterized for applying an lifting force among certain elements, and at the same time a support is introduced that absorbs the compression forces among the lower zones, preferably, the ends of two coinciding elements, in such a way that the produced moment in the lifting is balanced by the tractive forces in the reinforcement and the support compressive forces.
This method is subject to improvements or perfections, since with this method, the optimum results which are necessary for multipurpose sleepers are not obtained, as it is used with different track gages, the efforts to be supported do not correspond with total satisfaction when using one or the other gage.
Besides using an ascending force to elevate the concrete elements from their corresponding moulds, they need different means in the members used for rising, that allow the movement of the elements, which at the end suppose irregularities in the assembly.
For this reason, it was foreseen a new form of fabrication of this type of multipurpose sleepers, to which the present invention refers to.

DESCRIPTION OF THE INVENTION

The above mentioned multipurpose fabrication method, is essentially formed by a special main function which consists in maintaining the elevated position of the sleepers, when the moulds are lowered and the prestressing force of the cables which form the reinforcement is transferred, and in controlling the prestressing force between the sleepers reducing to a minimum the displacement of the sleepers along the bedframe, which has a length of the order of 90 metres or more.
Between the ends of each element and the neighbouring one, some compression plates are placed among which a compression member of sufficient amplitude is interposed in order to be supported in almost the totality of the plates, maintaining this member the beams position, without applying any ascending force, but maintaining the assembly in position while the bedframe is descending, obtaining with this the satisfaction of the double requirement allowing the movement or displacement of the sleepers in the ends of the bedframe, but limiting it to 2,5 cms.
This new disposition of plates and compression members also guarantees a gradual transmission of the prestressing along the whole bedframe, for all the prestressing cables disposition of the multipurpose sleepers.
This is essential since the new beams and transverse elements avoid that a cable, in spite of the different levels of existing cable may be detensioned before the rest, which would result in a serious damage both for the sophisticated sleeper object of the production as for the moulding equipment.
The new plates and compression element design absorbs all the prestressing force of the cables and provides stability against the possible rotation of the elements and at the same time it allows greater movements and maintains the correct position of the transverse beams.
It is important to point out that the benefit obtained when lifting the sleepers is at the same time of remarkable interest, as well as the assembly of the battery of moulds and systems of developing thereof, that allows a vertical movement instead of horizontal movement.
The reinforcement, always produced with prestressing cables, of different diameter in the upper and lower areas of the sleeper, is formed by four cables located in the upper area, of 3/8'' in diameter, and of eight of 1/4'' located in the lower area, by which it is obtained an improvement in adherence and a better distribution that facilitates the fabrication method.

With the method of reference, the multipurpose sleepers are obtained, which may be used in RENFE track gage or in INTERNATIONAL gage, of 2,6 m in length, prestressed by pretensioned reinforcement by adherence and fabricated in long line, that largely satisfies the geometrical resistant and mechanical requirements for working in both gages, as it can be verified by the results of the last trials carried out on December 16, 1993.

SLEEPER	TRIAL	CONFIG.	FO.10	FO.05	F_β
Multi-purpose	Estat. SBC	1.1	28.-	39.-	> 52.-
Multi-purpose	Estat. SBC	1.2	34.-	43.-	> 52.-
Multi-purpose	Estat. S. Cent	2.1	31.-	50.-	> 52.-
Multi-purpose	Fatigue SBC	1.1	28.-	39.-	> 52.-
Multi-purpose	Dinam. SBC	1.1	---	34.5	40.5
Multi-purpose	Dinam. SBC	1.2	---	43.-	52.-
Multi-purpose	Dinam. S. Cent	2.1	---	42.-	> 42.-

Where:
SBC= Section Under Rail
1.1= RENFE Gage
1.2= INTERNATIONAL Gage
2.1= Central Section
F0.10= Load that produces crack opening 0,1 mm
F0.05= Load that produces residual crack opening of 0,05 mm
F_β= Breaking load
Loads expressed in Tons.

These results are clearly higher than the specification requirements determined in the document PROTOCOL OF MECHANICAL TRIALS FOR MULTIPURPOSE MONOBLOCK SLEEPERS, RENFE 1992.
The obtained sleeper by this fabrication method which constitutes the invention, logically, besides being used in both gages (multipurpose) can be exclusively and indistinctively used in each one of the gages, without any prestressing modification, with the simple adoption of the corresponding anchorings.
The simultaneous use of two types of diameter of prestressing cables in the upper and lower areas, is used to make compatible the achievement of sufficient adherence length in the lower cables working with RENFE gage, with a geometrical disposition of cables that facilitates the concrete laying and compacting.
The external form and the disposition of the prestressing reinforcement allow the use of different anchorings, which is achieved changing the lower part of the mould in the area of anchoring. This sleeper of 2,6 m in length presents basically a keystone-shaped section except in the ribs corresponding to the anchorings and it varies linearly among the different sections of the sleepers, in such a way that taking as a base the length thereof, the minimum section corresponding to the central, will have a small base of 0,0577, a large base of 0,0846 and a height of 0,0769, while the maximum section corresponding to the end will have a small base of 0,0823, a large one of 0,1154 and a height of 0,0942.
In the upper face of the sleeper the corresponding ribs and the holes are foreseen for the coupling of the anchoring means of the different tracks with the corresponding gage required for each case.
The above mentioned method, achieves a result that, as it has been shown by the results of the trials, they considerably exceed any other type of similar sleeper, and at the same time allows the multipurpose sleepers fabrication in lines of three or more longitudinally neighbouring and similar assemblies in lateral lines of the order of four o more with which twenty four sleepers are simultaneously built in each multimould, allowing the coupling of ones following the others, giving a total of a minimum of 144 sleepers and a maximum of 216 sleepers per line, without any obstacle and all of them with the same mechanical characteristics, geometrical and of resistance for any type of track gage, for this reason its denomination of multipurposes is indicative of these sophisticated and precise sleepers.
The form, materials and dimensions, will be variable and in general, whatever would be incidental and secondary, provided that they do not alter, change or modify essentially the method which has been described.

Claims

1.- Multipurpose sleepers fabrication method, prestressing by prestressed reinforcement through adherence and fabricated in long line and moulded in rows and lines, characterized by placing the reinforcement consisting in prestressing cables, and by controlling the prestressing force between the sleepers, at the time that these are maintained in elevated position, while the moulds descend, suppressing the ascending forces of all type, minimizing the displacement of the sleepers along the bedframe.

2.- Multipurpose sleepers fabrication method, according to the first claim, characterized in placing between the ends of each element and the neighbouring one, some compression plates among which a compression member is interposed having such amplitude that is supported in almost the totality of the plates, maintaining this member the position of the sleepers without applying any ascending force.

3.- Multipurpose sleepers fabrication method, according to the first and second claims, characterized in using for the reinforcement four cables of large diameter in the upper area and eight cables of less diameter in the lower one, to improve the adherence and distribution that facilitates the fabrication method.