1. A construction method of a steel-concrete composite beam cable-stayed bridge is characterized in that,

for N-2, the pouring process of the wet joint (6) corresponding to the ith main beam segment is carried out after the forward moving process of the crane (7) corresponding to the (i + 2) th main beam segment;

for N-1 and i which are not less than and not greater than N, the pouring process of the wet joint (6) corresponding to the ith girder segment and the pouring process of the wet joint (6) corresponding to the (N-2) th girder segment are simultaneously carried out;

wherein N is the total number of main beam segments.

2. The construction method of a cable-stayed bridge of steel-concrete composite girder according to claim 1,

for N-3, the second stay cable tensioning procedure corresponding to the ith main beam section is carried out after the bridge deck (4) hoisting procedure corresponding to the (i + 3) th main beam section;

and for the condition that N-2 is not less than i and not more than N, simultaneously performing a second stay cable tensioning process corresponding to the ith main beam segment and a stay cable tensioning process corresponding to the (N-3) th main beam segment.

3. The construction method of the steel-concrete composite girder cable-stayed bridge according to claim 2, wherein in the second cable-tensioning process corresponding to each main girder segment, the elongation of the tensioned cable is controlled to be a preset value.

4. The method of claim 1, wherein a third cable-pull process is performed on each girder segment after the deck-laying of the composite steel-concrete girder cable-stayed bridge is completed.

5. The construction method of the steel-concrete composite beam cable-stayed bridge according to claim 1, wherein the main longitudinal beams (1) corresponding to the main beam sections are all box-shaped sections.

6. The construction method of the steel-concrete composite girder cable-stayed bridge according to claim 1, wherein main longitudinal girders (1) corresponding to adjacent main girder sections are welded.

7. The construction method of the steel-concrete composite beam cable-stayed bridge according to claim 1, wherein in the first cable stretching process corresponding to each main beam section, the internal force value of the stretched cable is controlled to be a preset value.

8. The construction method of the steel-concrete composite girder cable-stayed bridge according to claim 1, wherein when the deck slab (4) corresponding to each main girder segment is hoisted, the hoisting direction of the deck slab (4) is determined by the difference of the elevations of the main longitudinal girders (1) on the upstream side and the downstream side of the site.

9. The construction method of the steel-concrete composite girder cable-stayed bridge according to claim 8, wherein if the elevation of the upstream side main longitudinal girder (1) is greater than that of the downstream side main longitudinal girder (1), the bridge deck (4) is hoisted in the order of the upstream side and the downstream side; if the elevation of the upstream side main longitudinal beam (1) is smaller than that of the downstream side main longitudinal beam (1), hoisting the bridge deck (4) in the sequence of the downstream side and the upstream side; and if the elevation of the upstream side main longitudinal beam (1) is equal to the elevation of the downstream side main longitudinal beam (1), hoisting the bridge deck (4) in the sequence of first middle part and then two sides.

Background

In engineering construction, the steel-mixed composite beam fully exerts the characteristics of concrete compression and reinforcing steel bar tension, and has the advantages of low cost, convenience in construction, high span and good durability compared with a concrete beam structure.

Through summarizing and analyzing the engineering practice for many years, the influence of the main beam construction process of the steel-concrete composite beam cable-stayed bridge on the rationality and the internal force state of the engineering is found to be great. Therefore, in the construction work, it is necessary to determine the construction process in consideration of the construction period and to ensure the safety and the rationality of the structure.

In the design of the steel-concrete superposed beam cable-stayed bridge, the construction process of the steel-concrete superposed beam cable-stayed bridge generally adopts the mode that the pouring of wet joints is not delayed, namely, the wet joints of the current main beam segments are poured immediately after the bridge deck of the current main beam segments are hoisted aiming at each main beam segment, and the method has the advantages of longer construction period, inconvenient field construction and unfavorable control on the line shape and stress of the structure.

Disclosure of Invention

The invention aims to provide a construction method of a steel-concrete composite beam cable-stayed bridge, aiming at the defects of long construction period, inconvenient site construction and difficult control of structural line shape and stress of the existing construction method of the steel-concrete composite beam cable-stayed bridge, which can effectively shorten the construction period, improve the construction efficiency and ensure the construction quality and safety.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a construction method of a steel-concrete composite beam cable-stayed bridge is characterized in that:

for N-2, the pouring process of the wet joint corresponding to the ith main beam section is carried out after the forward moving process of the crane corresponding to the (i + 2) th main beam section;

for N-1 and i are not less than N, the pouring process of the wet joint corresponding to the ith girder segment and the pouring process of the wet joint corresponding to the (N-2) th girder segment are simultaneously carried out;

wherein N is the total number of main beam segments.

Further, for the situation that i is less than or equal to N-3, a second stay cable tensioning procedure corresponding to the ith main beam section is carried out after a bridge deck hoisting procedure corresponding to the (i + 3) th main beam section; and for the condition that N-2 is not less than i and not more than N, simultaneously performing a second stay cable tensioning process corresponding to the ith main beam segment and a stay cable tensioning process corresponding to the (N-3) th main beam segment.

As a preferable mode, in the second stay cable tensioning process corresponding to each main beam segment, the elongation of the tensioned stay cable is controlled to be a preset value.

And further, after the bridge deck pavement of the steel-concrete composite beam cable-stayed bridge is finished, performing a third cable tensioning process on each main beam segment.

Preferably, the main longitudinal beams of each main beam segment are box-shaped sections.

Preferably, main longitudinal beams corresponding to the adjacent main beam sections are welded.

As a preferable mode, in the first stay cable tensioning process corresponding to each main beam segment, the internal force value of the tensioned stay cable is controlled to be a preset value.

Preferably, when the bridge deck corresponding to each main beam segment is hoisted, the hoisting direction of the bridge deck is determined by the difference of the elevations of the main longitudinal beams on the upstream side and the downstream side of the site.

Preferably, if the elevation of the upstream side main longitudinal beam is larger than that of the downstream side main longitudinal beam, hoisting the bridge deck in the order of the upstream side and the downstream side; if the elevation of the upstream side main longitudinal beam is smaller than that of the downstream side main longitudinal beam, hoisting the bridge deck according to the sequence of the downstream side and the upstream side; and if the elevation of the upstream side main longitudinal beam is equal to that of the downstream side main longitudinal beam, hoisting the bridge deck in the sequence of first middle and then two sides.

Compared with the prior art, the invention has the following beneficial effects:

first, through two segmentations go on with wet seam casting lag, can reach the effect of showing reduction of erection time under the condition that guarantees that the structure atress satisfies the requirement, and more make things convenient for the construction on-the-spot. The late placement of the wet joints also reduces the tensile stress of the deck slab to avoid cracking of the deck slab.

And secondly, the secondary tensioning of the stay cable is delayed by three sections, so that the stress of the steel beam at the part without pouring the wet joint can be reduced, and the safety of the structure is ensured.

And thirdly, the secondary tensioning of the stay cable is controlled by adopting the elongation, so that the internal force of the stay cable can be accurately controlled, and the line shape of the bridge can be well controlled, therefore, the secondary tensioning of the stay cable is delayed by three sections, and errors generated in the aspect of elevation in the construction process can be reduced.

Fourthly, the hoisting sequence of the bridge deck is determined by the height difference of the upper vernier and the lower vernier of the main longitudinal beam, so that the condition that the upper vernier and the lower vernier are asymmetric easily generated in construction can be solved to a certain extent, and the influence on the stress of the bridge due to the uneven thickness of the bridge deck during pavement is avoided.

Drawings

Fig. 1 is a schematic view of hoisting a main longitudinal beam.

Fig. 2 is a schematic view of a hoisting cross beam and a small longitudinal beam.

Fig. 3 is a schematic diagram of the initial tension of the stay cable.

Fig. 4 is a schematic view of the installation of a bridge deck.

Fig. 5 is a schematic diagram of two cables.

Fig. 6 is a schematic view of the crane advancing.

FIG. 7 is a schematic view of a wet cast joint.

FIG. 8 is a construction flow diagram of the present invention at a main beam section of the intermediate standard section.

In the figure: 1-main longitudinal beam, 2-cross beam, 3-small longitudinal beam, 4-bridge deck, 5-primarily tensioned inhaul cable, 6-wet joint, 7-crane and 8-secondarily tensioned inhaul cable.

Detailed Description

The following further describes the embodiments of the present invention with reference to the drawings.

In the construction method of the steel-concrete composite beam cable-stayed bridge, the main beam is hoisted by adopting a single high-altitude assembly to form a bridge floor, the pouring of a wet joint 6 is carried out by two sections after delay, and the secondary tensioning of a guy cable is carried out by three sections after delay, which comprises the following steps:

for N-2, the pouring process of the wet joint 6 corresponding to the ith main beam section is carried out after the forward moving process of the crane 7 corresponding to the (i + 2) th main beam section; for N-1 and i are not less than N, the pouring process of the wet joint 6 corresponding to the ith girder segment and the pouring process of the wet joint 6 corresponding to the (N-2) th girder segment are simultaneously carried out; wherein N is the total number of main beam segments.

For N-3, the second stay cable tensioning procedure corresponding to the ith main beam section is carried out after the bridge deck 4 hoisting procedure corresponding to the (i + 3) th main beam section; and for the condition that N-2 is not less than i and not more than N, simultaneously performing a second stay cable tensioning process corresponding to the ith main beam segment and a stay cable tensioning process corresponding to the (N-3) th main beam segment.

And in the second stay cable tensioning process corresponding to each main girder section, controlling the elongation of the tensioned stay cable to be a preset value.

And after the bridge deck pavement of the steel-concrete composite beam cable-stayed bridge is finished, performing a third stay cable tensioning procedure on each main beam segment.

The main longitudinal beams 1 corresponding to the main beam sections are all box-shaped sections. And main longitudinal beams 1 corresponding to adjacent main beam sections are welded. After the downstream side main longitudinal beam 1 is welded, the upstream side main longitudinal beam 1 is hoisted and welded.

And in the first stay cable tensioning process corresponding to each main beam section, controlling the internal force value of the tensioned stay cable to be a preset value.

When the bridge deck 4 corresponding to each main beam section is hoisted, the hoisting direction of the bridge deck 4 is determined according to the difference of the elevations of the main longitudinal beams 1 on the upstream side and the downstream side on the site. If the elevation of the upstream side main longitudinal beam 1 is greater than that of the downstream side main longitudinal beam 1, hoisting the bridge deck 4 in the sequence of the upstream side and the downstream side; if the elevation of the upstream side main longitudinal beam 1 is smaller than that of the downstream side main longitudinal beam 1, hoisting the bridge deck 4 in the sequence of the downstream side and the upstream side; if the elevation of the upstream side main longitudinal beam 1 is equal to the elevation of the downstream side main longitudinal beam 1, hoisting the bridge deck 4 in the order of the middle and the two sides.

Taking the main beam segment of the middle standard section as an example, the construction method of the steel-concrete composite beam cable-stayed bridge comprises the following steps:

step 1, hoisting a main longitudinal beam 1 corresponding to the nth section of main beam segment, as shown in fig. 1.

And 2, hoisting the cross beam 2 and the small longitudinal beam 3 corresponding to the nth section of main beam segment, as shown in fig. 2.

And 3, tensioning the inhaul cable corresponding to the nth section of main beam segment for the first time, as shown in fig. 3. The initial tensioning of the stay cable is controlled by the internal force value of the stay cable. The pull cord 5 after initial tensioning is shown in fig. 3.

And 4, hoisting the bridge deck 4 corresponding to the nth section of main beam segment, as shown in fig. 4. The hoisting sequence of the bridge deck 4 is determined by the elevation difference value of the upstream and downstream main longitudinal beams 1, namely, if the elevation of the upstream side main longitudinal beam 1 is higher than that of the downstream side main longitudinal beam 1, the bridge deck 4 on the upstream side is hoisted firstly; otherwise, hoisting the bridge deck 4 on the downstream side; if the elevations of the upstream and downstream main longitudinal beams 1 are basically the same, the hoisting is symmetrically carried out from the middle to the two sides.

And 5, tensioning the inhaul cable corresponding to the nth-3 section of the main girder segment for the second time, as shown in fig. 5. The secondary tensioning of the stay cable is controlled by elongation, wherein the length of the non-prestressed cable before tensioning is converted by cable force obtained by field actual measurement, and the length of the non-prestressed cable after tensioning is a design theoretical value. The two following cables 8 are seen in fig. 5.

Step 6, the deck crane 7 is moved forward as shown in fig. 6.

And 7, pouring a wet joint 6 corresponding to the n-2 section of the girder segment, as shown in fig. 7.

The construction flow chart of the invention at the main beam section of the middle standard section is shown in fig. 8.

Since the wet joint 6 placement is delayed by two sections, the first two main beam sections are constructed without the wet joint 6 placement process, and the wet joints 6 of the last three sections (i.e., the three sections before the closure) can be placed together.

Because the secondary tensioning of the stay cable is delayed by three sections, the secondary tensioning process of the stay cable is not performed when the first three sections of main beam sections are constructed, and the secondary tensioning process of the stay cable of the last four sections can be completed together.

The beneficial effects of the method of the invention are proved by experiments:

the construction method of the prior art is applied, wherein the wet joint 6 and the inhaul cable are not delayed, and the construction period of each segment is 10 days. After the method is adopted, the construction period of each segment is shortened to 7 days, and the problem of short construction period on site is well solved. After the method is adopted, adverse conditions such as cracking of the bridge deck 4, overlarge stress of the steel beam and the like are avoided in the field construction process, and the safe construction of the structure can be ensured.

By applying the existing method, the situation that the elevation is inconsistent between the upstream main longitudinal beam 1 and the downstream main longitudinal beam 1 is particularly found in the construction process. In the invention, the hoisting sequence of the bridge deck 4 in the construction process is adjusted, and in the embodiment, the height difference of 20mm between the upstream and the downstream can be adjusted to the maximum extent by adjusting the hoisting sequence of the bridge deck 4.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.