WO2003035982A1

WO2003035982A1 - A prestressed track girder and its manufacture method

Info

Publication number: WO2003035982A1
Application number: PCT/CN2002/000463
Authority: WO
Inventors: Xiangming Wu; Zhong Wu; Tinzhu Ren
Original assignee: Shanghai Maglev Transportation Development Co., Ltd
Priority date: 2001-10-26
Filing date: 2002-07-01
Publication date: 2003-05-01
Also published as: HK1045341B; CN1344836A; HK1045341A1; CN1128900C

Abstract

This invention relates to a prestressed track girder applied in the rapid orbit transit and its manufacture method, said prestressed track girder comprising the top plate (1), the base plate (2) and the web (3), respectively setting several axes pretensioning prestressed bundles (5) at the right-and-left positions (21, 22) of the top plate (1) and the base plate (2), setting several eccentric pretensioning prestressed bundles (6) at the center position (20) of the base plate (2), setting a first posttensioning prestressed bundle (7) and a second posttensioning prestressed bundle (8) in the conic-parabola shape at the two webs (3), setting the external prestressed bundles at the cavity (4) and the top plate (1). As to the culvinear track girder, setting the transverse eccentric pretensioning prestressed bundles (9) at the top plate (1) and the base plate (2) inside said curve. Under the condition of holding the axes of the girder in a pressed state at the stage of construction and management, the deformation of the track girder aroused by the contract and creep collapse of the concrete is controlled in the range of < 1mm.

Description

Prestressed track beam and manufacturing method thereof

The invention relates to a running track of a rail vehicle, in particular to a prestressed track beam for high-speed rail transportation such as magnetic levitation and a manufacturing method thereof. technical background

The maglev train is a high-speed delivery system. When running at high speed, it has extremely high precision requirements for the support structure, that is, the track structure. First of all, as far as the mechanical characteristics of the track structure are concerned, the track structure is required to have very strict deformation requirements under the action of train moving load, ambient temperature and long-term load. At the same time, the dynamic characteristics of the track structure are strictly limited. The first-order natural frequency must be greater than 1.1 times the running speed of the vehicle to the span of the track structure. Secondly, train running systems such as maglev trains have imposed very strict accuracy requirements on the functional area of the track structure. The functional area is located on the top and sides of the track structure, including the sliding surface on both sides of the top surface, the guide surfaces on both sides of the train, and the stator. For the bottom surface of the iron core, the accuracy requirements for the above three functional surfaces are all within 1mm or 1mm (0.4mm). The track structure requirements of the maglev train system above determine that the track structure of the maglev train has a large difference from the conventional railway bridge or track structure.

According to the structural analysis and calculation, it is known that the track structure that meets the technical requirements for the operation of the maglev train requires sufficient rigidity. Unlike a beam in the traditional sense, it is no longer a stress (internal force) control design, but a deformation control design. For such a large rigidity, cracks will appear in the reinforced concrete structure during normal operation, which reduces the stiffness of the beam and the span cannot be too large, so this structure is difficult to meet the requirements of magnetic levitation; although the steel structure is lighter, the deformation is easier to control However, it is a thin-walled structure. The section that meets the rigidity requirements of the magnetic levitation track structure must be made large and the engineering cost is high. The prestressed concrete structure has the advantages of high rigidity and the ability to adjust the deformation of each stage of construction through prestress. Rail transit, such as magnetic levitation, requires highly deformed rail structures.

For conventional prestressed concrete structures, concrete shrinkage and creep have a great effect on the long-term deformation of the beam, and the magnetic suspension system requires that the long-term deformation due to material factors is within the long-wave error range (the maximum deformation cannot exceed 1mm); and it is processed in the functional area There are also stricter restrictions on beam deformation. This is because the connector is already embedded in the beam body when the beam is manufactured. When the connector is machined, the connector and functional parts are connected with high-strength bolts, and the machining allowance of the connector is limited. For traditional prestressed design, it is often stress control. The prestressed design is performed according to the most unfavorable combination of internal forces caused by various loads. The calculation of deformation is only used as a check in normal use. The general error is 10mm. However, for a magnetic levitation system, the long-term deformation must be within the long-wave error range in the vertical and horizontal directions (the maximum deformation cannot exceed 1 mm). Therefore, how to carry out the prestress design becomes the key to determine whether the prestressed concrete structure can meet the requirements of the magnetic levitation system. Summary of the Invention

The technical problem to be solved by the present invention is to provide a prestressed track beam and its manufacturing and installation method according to the prestress design to ensure that the track beam can always meet the deformation requirements of the magnetic suspension track beam.

The essence of the technical solution of the present invention is to control the axial compression state during each construction stage, and control the deformation of the track beam segment caused by the shrinkage and creep of the concrete to a small range. During the prefabricated rail, the prestress is applied in three stages: one pre-tensioning method and two post-tensioning methods.

Specifically, the prestressed track beam of the present invention includes a beam top plate, a beam bottom plate, and a beam web, which are characterized by:

1. A plurality of pre-tensioning methods of the axial center pretensioning method are respectively arranged in the beam top plate and the left and right parts of the beam bottom plate, so that the moments of the prestress of the upper and lower edges on the section center of gravity axis are equal, and the pretensioning method is ensured in all axial centers Axial compression of the full section under prestress. The number of pre-tensioned prestressing beams is determined based on the calculation of variable loads, other variable loads, and construction loads.

2. Set several eccentric pre-tensioning prestressing beams in the middle of the bottom plate of the track beam to balance the self-weight of a part of the beam body, determine its isolation length according to the bending moment diagram, and generate prestressing force at the lower edge of the section. The number of eccentric pretensioning prestressing beams is determined according to the deformation control requirements and the stress during construction.

3. In the web of the track beam, set a first post-tensioning prestressing beam according to the second parabolic curve to balance the internal force generated by the unbalanced beam's own weight due to the eccentric pre-tensioning pretensioning. The full section of the track beam is under axial compression.

4. A second post-tensioning prestressing beam is also set in each of the two webs of the track beam according to the second parabola to balance the weight of auxiliary facilities such as functional parts and the previously generated due to shrinkage and creep. The internal force is applied with an equivalent load of the same weight as the accessory equipment such as functional parts during tensioning. After the second post-tensioning method is applied, the full cross-section of the track beam is adjusted to the axial compression state again.

For curved track beams, the top and bottom plates inside the curve should also be provided with transverse eccentric pretensioning prestressing beams, the number of which is determined based on the beam's own weight and the lateral bending moment generated by the weight of the attached equipment.

5. In order to adjust the long-term deformation of the prestressed beam, an external prestressing beam is also provided, that is, it is fixed on the top surface of the both sides of the beam floor of the cavity of the prestressed beam at about 1/4 span. In the steering device, two polygonal external prestressed pipes pass through the steering device and the beam top plate for the external prestressed beam to pass through. The anchoring ends of the external prestressed beam are located at the top surfaces of the two ends of the beam top plate.

As mentioned above, the essence of the technical solution of the present invention is that during the construction and operation stages, the track beam theoretically maintains the axial compression state, and the deformation of the track beam segment caused by shrinkage and creep is controlled within 1 mm. The manufacturing method of the prestressed track beam of the present invention includes the following steps:

(1) Before the prestressed concrete is poured, according to the design, a number of prestressed bundles of the axial pretension method and several prestressed bundles of the eccentric pretension method are stretched on the pouring platform;

(2) The first and second post-tensioned pre-stressed beam corrugated tubes;

(3) pouring concrete;

(4) When the concrete reaches about 75% of the design strength, the pre-tensioned beam is cut to transport the track beam to the storage place;

(5) The ordinary clip group anchor system is used to tension the first post-tensioned prestressed beam passing through the bellows to balance the internal force generated by the unbalanced beam body's own weight due to the eccentric pre-tensioned prestressed beam. The full section of the beam is under axial compression;

(6) Equivalent loads such as functional parts are placed on the beam body. The second post-tensioned prestressed corrugated pipe is passed through the second post-tensioned prestressed beam and tensioned to balance auxiliary equipment such as functional parts. The weight and internal forces due to shrinkage and creep before the second post-tensioning make the full cross-section of the track beam to the axial compression state again;

For curved beams, in step (1) of the above manufacturing method, a lateral eccentric pretensioning prestressing beam should be set in the top and bottom plates at the inside of the curve at the same time. In order to adjust the long-term deformation of the prestressed track beam, in step (2) of the above manufacturing method, an external prestressed pipe and a steering device are embedded. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic diagram of a prestressed beam structure of a linear beam according to a first embodiment of the prestressed track beam of the present invention. Fig. 2 is a schematic sectional structural view of a fulcrum of a linear beam according to the first embodiment of the prestressed track beam of the present invention. Fig. 3 is a schematic diagram of a mid-span cross-section structure of a linear beam according to a first embodiment of the prestressed track beam of the present invention. FIG. 4 is a schematic diagram of a prestressed cable structure of a curved beam according to a second embodiment of the prestressed track beam of the present invention. Fig. 5 is a schematic structural sectional view of a fulcrum of a curved beam according to a second embodiment of the prestressed track beam of the present invention. Fig. 6 is a schematic diagram of the mid-section structure of a curved beam span of a prestressed track beam according to a second embodiment of the present invention. FIG. 7 is a schematic diagram of an external prestressed beam structure of a prestressed track beam of the present invention.

In the picture:

1 one beam top plate 11 one beam top plate

12—anchor end 2—beam floor

20—the middle 2

22—Right 23—Top surface of beam floor

24—steering device 25—external prestressed pipeline

3—beam web 4 a cavity

5—Axial pretensioning prestressing beam 6—Eccentric pretensioning prestressing beam

7—First post-tensioned prestressed beam 8—Second post-tensioned prestressed beam

9 a transverse eccentric pretensioning prestressed beam

Please refer to FIG. 1, FIG. 2 and FIG. 3. The prestressed track beam of the present invention includes a beam top plate 1, a beam bottom plate 2, and a beam web 3. The characteristics are as follows: inside the track beam top plate 1 and the left portion 21 of the beam bottom plate 2. A number of eccentric pretensioning prestressing beams 5 are set at the two parts of the right and the right part 22, and a number of eccentric pretensioning prestressing beams 6 are set at the middle part 20 of the track beam bottom plate 2; A first post-tensioned prestressed beam 7 is arranged in each of the parabolic shapes, and a second post-tensioned prestressed beam 8 is arranged in each of the second parabolic shapes. For curved track beams, in addition to the prestressed beams configured as described above, laterally eccentric pretensioned prestressed beams 9 should also be arranged in the top and bottom plates inside the curve, as shown in Figures 4, 5 and 6.

FIG. 7 is a schematic diagram of an external prestressed beam structure of a prestressed track beam of the present invention.

Because magnetic suspension has very high requirements for long-term deformation of the beam, and the mechanism of concrete shrinkage and creep is relatively complex and has large dispersion, the present invention also includes an adjustable measure for long-term long-term deformation-an external prestressing beam. Its specific structure is shown in FIG. 7: Four steering devices 24 are fixedly arranged on the top surface 23 on both sides of the beam bottom plate 2 of the cavity 4 of the prestressed track beam, and a total of four steering devices 24 are provided, two The polygonal external prestressed pipe 25 passes through the steering device 24 and the top plate 1 for the external prestressed beam to pass through. The anchoring ends 12 of the external prestressed beam are located at both ends of the beam top plate 1. The external prestressed beam adopts a polygonal line shape, and the turning point is set at the steering device 24.

Once the long-term deformation of the prestressed track beam does not meet the requirements (<lmm), the external prestressed beam is penetrated into the external stress pipe 25, and then the tensile force is determined according to the actual deformation condition, tensioned, and then anchored. Therefore, the prestressed track beam of the present invention can adjust the prestress at any time according to the actual needs to ensure the long-term good state of the prestressed track beam.

The manufacturing method of the prestressed track beam of the present invention is as described above, and is not repeated here.

The specific data of a prestressed track beam of the present invention are listed below:

A 24.685-meter concrete beam is provided with 57 beams of the axial pretensioning prestressing beam, of which 19 beams are in the beam top plate 1, 38 beams are in the beam bottom plate 2, and 12 beams are eccentric pretensioning prestressing beams.

The bending moment of the first post-tensioned prestressed beam in the mid-span section of the beam: M _yl = -2529kN · m The bending moment of the eccentric pre-tensioned pre-stressed beam in the mid-section of the beam: M _y . = —1690kN · m The moment of the beam (including the connector) in the mid-span section: M _gQ = 4298kN · m The moment in the mid-span section of the second post-tensioned prestressed beam: M _y2 = — 945kN · m Bending moment in the section due to the shrinkage and creep of the concrete before the second post-tensioning prestressed beam tensioning: M _g3 = 311kN * m

Moment of cross section of auxiliary equipment such as functional parts in the span: M _sl = 630kN · m

Claims

Claim

1. A prestressed track beam suitable for high-speed rail transit, comprising a beam top plate (1), a beam bottom plate (2), and a beam web (3), which are characterized by:

(1) Set several axial pretensioning prestressing beams (5) in the left and right parts (21, 22) of the beam top plate (1) and the beam bottom plate (2);

(2) Set several eccentric pretensioning prestressing beams (6) in the middle part (20) of the bottom plate (2) of the track beam;

(3) Web plates on both sides of the track beam (3) Set a first post-tensioning method prestressed beam (7) each in the shape of a quadratic parabola;

(4) Web plates on both sides of the track beam (3) Set a second post-tensioning prestressing beam (8) each in the shape of a quadratic parabola.

2. The prestressed track beam according to claim 1, characterized in that for curved track beams, a transverse eccentric pretensioning prestressing beam is further provided in the top plate (1) and the bottom plate (2) inside the curve.

(9).

3. The prestressed track beam according to claim 1 or 2, characterized in that it is about 1/4 on the top surfaces (23) on both sides of the beam floor (2) of the cavity (4) of the prestressed track beam. A steering device (24) is fixedly arranged at the span, and two polygonal external prestressed pipes (25) pass through the steering device.

(24) and top plate (1), the anchoring ends (12) of which are located at the top surfaces of both ends of the beam top plate (1).

4. The method for manufacturing a prestressed track beam according to claim 1, further comprising the following steps:

(1) Before the prestressed concrete is poured, according to the design, several axial pretensioned prestressed beams (5) and several eccentric pretensioned prestressed beams (6) are stretched on the pouring platform according to the design;

(2) Setting up a bellows (7 ', 8') ready to install the first and second post-tensioned prestressed beams (7, 8);

(3) pouring concrete;

(4) When the concrete reaches about 75% of the design strength, the pre-tensioned beam is cut to transport the track beam to the storage place; (5) Using a common clip group anchor system, the first post-tensioning prestressed beam (7) passing through the bellows (7) is stretched to give due prestress to balance the eccentric pretensioning prestressed beam (6) The internal force generated by the unbalanced beam body's own weight makes the full section of the track beam under axial compression;

(6) Keep the track beam in the first post-tensioned prestressing beam. (7) The state of full-section axial compression after tensioning for a period of time, so that concrete shrinkage and creep can occur more fully. Equivalent load is placed on the beam body, and the second post-tensioned prestressed corrugated pipe (8 ') is inserted into the second post-tensioned pre-stressed beam (8) and tensioned to adjust the full cross-section of the track beam again. To the axial compression state.

5. The method for manufacturing a prestressed track beam for a high-speed rail transit according to claim 4, characterized in that when manufacturing a prestressed curved track beam, in step (1), the top plate on the inside of the curve of the curved track beam should be simultaneously (1) and the bottom plate (2) are provided with a transverse eccentric pretensioning prestressing beam (9).

6. The method for manufacturing a high-speed rail transit prestressed track beam according to claim 4 or 5, characterized in that in step (2), an external prestressed beam pipe (25) should also be preset.