Standardized construction method of steel core-UHPC composite box girder

Abstract

The application discloses a kind of steel inner core-UHPC combined box girder standardization construction methods, comprising the following steps: S1: prefabricated steel inner core section;S2: steel inner core is hoisted to the bottom mould above;S3: positioning steel is welded to the bolt on the outer surface of steel inner core, then the placement and binding of steel mesh are carried out;S4: side mould is installed to the bottom mould;S5: UHPC box girder is poured;S6: prefabricated box girder of pouring completion is pushed forward, the steel inner core of next section prefabricated box girder is welded with the steel inner core of prefabricated box girder of pouring completion, and steps S3-S5 are carried out to next section prefabricated box girder;S7: repeat step S6 until whole bridge is pushed into place.The application improves the construction efficiency and construction quality of box girder, reduces the use of large mechanical equipment in construction, reduces construction risk, avoids the construction of temporary prestressed cable and temporary pier in conventional box girder pushing construction, and further improves the overall construction quality and construction efficiency of bridge structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building engineering, and in particular to a standardized construction method of a steel inner core-UHPC combined box girder. BACKGROUND

[0002] The box girder is a kind of girder in bridge engineering, which is hollow inside and has flanges on both sides of the upper part, similar to a box, hence the name. The steel inner core-UHPC combined box girder can better solve the problems of mid-span deflection and body cracking commonly existing in traditional long-span prestressed concrete box girder bridges. The incremental launching method has the advantages of convenient construction, good economy, no restriction by traffic or terrain under the bridge, etc., and has obvious advantages in mountain valley, high pier and cross-line bridges. In the case of deep valley in mountainous areas, the incremental launching construction not only reduces the cost of building temporary piers, but also improves the construction efficiency and saves the construction period.

[0003] At present, the largest incremental launching span of a concrete girder bridge in China is the Fujian Qiudun Bridge completed in 1992, with an incremental launching span of 52m. However, after decades of development, the incremental launching span of the concrete girder bridge has not been significantly improved. At present, the incremental launching span of the concrete girder bridge is basically limited within 60m, which is difficult to meet the needs of deep valley terrain in mountainous areas, cross-line bridges and long-span navigation. Compared with the traditional concrete box girder, the combined box girder has good performance in resisting positive and negative bending moments, and is very suitable for incremental launching construction. In the process of segment production, the steel inner core can be used as a pouring inner mold, without the need for additional erection and removal of the inner mold. When the steel inner core-UHPC combined box girder structure is combined with the incremental launching construction method, the technical bottleneck of the limited span of the conventional concrete girder can be broken through, and the span of the concrete box girder incremental launching can be spanned from 60m to 100m.

[0004] The steel inner core-UHPC combined box girder has the advantages of convenient construction and high efficiency, but due to the differences in construction technology between the steel inner core-UHPC combined box girder and the traditional concrete box girder, if a programmed and standardized construction process cannot be developed according to the characteristics of the combined box girder, it will not only be difficult to take advantage of the key advantages of the combined box girder in construction, but also may have adverse effects on the overall quality of the structure and the construction of the project. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the deficiencies of the prior art and provide a convenient and efficient standardized construction method of a steel inner core-UHPC combined box girder.

[0006] To solve the above technical problems, the present application provides a standardized construction method of a steel inner core-UHPC combined box girder, comprising the following steps:

[0007] S1, precast steel inner core segment;

[0008] S2, hoist the steel inner core above the bottom mold plate;

[0009] S3: welding the positioning steel bars to the pegs on the outer surface of the steel inner core, and then placing and binding the reinforcement mesh;

[0010] S4: installing the side formwork to the bottom formwork;

[0011] S5: pouring the UHPC slurry from one side of the side formwork first, and then pouring the UHPC slurry to both sides of the side formwork simultaneously when the UHPC slurry flows through the bottom formwork and reaches the preset height on the other side of the side formwork, until the top UHPC slurry is poured to completion;

[0012] S6: installing the end of the prefabricated box girder poured to completion to the steel guide beam, pushing forward, welding the steel inner core of the next section of the prefabricated box girder to the steel inner core of the prefabricated box girder poured to completion, and performing steps S2-S4 on the next section of the prefabricated box girder;

[0013] S7: repeating step S6 until the whole bridge is pushed into place.

[0014] As a further improvement of the method of the application: between the implementation of step S1, construction preparation is also required, which specifically includes the following steps:

[0015] erecting a prefabricated box girder section construction platform and a pushing construction platform, fixing the bottom formwork to the prefabricated box girder section construction platform, and the pushing construction platform including an electrically connected pushing control system and a steel guide beam, when a section of the prefabricated box girder is prefabricated, directly pushing construction is performed by the pushing construction platform.

[0016] As a further improvement of the method of the application: step S5 specifically includes:

[0017] S51: pouring the UHPC slurry from one side of the side formwork first, and then pouring the UHPC slurry to both sides of the side formwork simultaneously when the UHPC slurry flows through the bottom formwork and reaches the preset height on the other side of the side formwork, until the top UHPC slurry is poured to completion;

[0018] S52: after pouring, covering the UHPC box girder 12 with a thermal insulation quilt, and using a temperature of 90-95°C for steam curing for a preset time.

[0019] As a further improvement of the method of the application: step S5 also includes:

[0020] S53: chiseling the end of the UHPC box girder.

[0021] As a further improvement of the method of the application: the steel inner core is formed by welding steel plates, and steel transverse partitions are arranged on the inner side of the steel inner core.

[0022] As a further improvement of the method of the present application: the pegs are welded on the steel plate, or welded on the outer surface of the shaped steel inner core.

[0023] As a further improvement of the method of the present application: the bottom plate steel bars are bound on the bottom formwork.

[0024] As a further improvement of the method of the present application: a plurality of attached vibrators are arranged in an array under the bottom formwork.

[0025] As a further improvement of the method of the present application: when pouring the bottom plate and the web plate of the UHPC box girder, the side formwork is provided with a pouring opening slot formwork;

[0026] As a further improvement of the method of the present application: both the bottom formwork and the side formwork are reusable formworks.

[0027] The present application has the following beneficial effects:

[0028] 1. The binding of the web plate steel bars and the top plate steel bars of the UHPC can be positioned and fixed by means of the pegs on the outer surface of the steel inner core, which is beneficial to improve the construction quality and construction speed of the box girder steel cage;

[0029] 2. The steel inner core-UHPC combined box girder in the present application does not need to be installed with an inner formwork when pouring, only needs to be installed with a bottom formwork and a side formwork, simplifies the formwork engineering, and reduces the manufacturing cost;

[0030] 3. The pouring of the UHPC is first poured from one side of the side formwork, and then poured to both sides of the side formwork after the UHPC slurry flows to the other side of the side formwork to a preset height, which can effectively ensure the pouring compactness requirement of the thin-walled plate of the combined box girder and improve the pouring quality of the thin-walled combined box girder;

[0031] 4. The standardization construction method of the steel inner core-UHPC combined box girder effectively connects the combined box girder standard segment prefabrication and the incremental launching construction process, fully guarantees the overall construction quality of the structure, maximizes the inherent advantages of the combined box girder in the construction level, and improves the overall construction quality and construction efficiency of the bridge structure;

[0032] 5. The standardization construction method of the steel inner core-UHPC combined box girder can eliminate the temporary pier and the temporary prestressed cable used in the incremental launching of the conventional concrete box girder, and realizes the span of 60m~100m of the concrete box girder.

[0033] In addition to the purposes, features and advantages described above, the present application has other purposes, features and advantages. The present application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, illustrate the preferred embodiments of the application and assist in

[0035] Figure 1 is a flow chart of the standardized construction method of the composite box girder of the present application;

[0036] Figure 2 is a structural schematic diagram of the steel inner core of the present application;

[0037] Figure 3 is a structural schematic diagram of the UHPC box girder of the present application;

[0038] Figure 4 is a steam curing schematic diagram of the UHPC box girder of the present application;

[0039] Figure 5 is a schematic diagram of the integrated construction of the prefabrication platform and the incremental launching of the composite box girder of the present application;

[0040] Figure 6 is a schematic diagram of the UHPC pouring method of the composite box girder of the present application;

[0041] In the drawings, various reference numerals represent:

[0042] 1, prefabricated box girder; 11, steel inner core; 111, stud; 112, steel cross partition plate; 12, UHPC box girder; 2, bottom formwork; 21, attached vibrator; 3, side formwork; 4, prefabricated box girder segment construction platform; 5, incremental launching construction platform; 51, steel guide beam; 6, pouring opening slot-shaped formwork; 7, thermal insulation cover. DETAILED DESCRIPTION

[0043] The embodiments of the present application are described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as limited and covered by the claims.

[0044] In addition, unless otherwise defined and limited, the technical terms or scientific terms used in the description of the present application shall be the general meaning understood by the general technical personnel in the field to which the present application belongs. The words indicating the direction or position relationship such as "upper", "lower", "left", "right", "center", "vertical", "horizontal", "inner", "outer" and the like used in the description of the present application are only used to indicate the relative direction or position relationship, and not to imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and the relative position relationship thereof may also change accordingly when the absolute position of the described object changes, and therefore cannot be understood as a limitation on the present application. The "first", "second", "third" and the like used in the description of the present application are only for the purpose of description, to distinguish different components, and cannot be understood as indicating or implying relative importance. The "one", "a" or "the" and the like used in the description of the present application should not be understood as an absolute limitation on the quantity, but should be understood as the presence of at least one. The "includes" or "contains" and the like used in the description of the present application means that the elements or objects before the word cover the elements or objects listed after the word and their equivalents, and does not exclude other elements or objects.

[0045] It should also be noted that, unless otherwise explicitly specified and limited, the "installation", "connection", "connection" and the like used in the description of the present application should be understood in a broad sense, for example, the connection can be a fixed connection, or a detachable connection, or an integral connection; can be a mechanical connection, or an electrical connection; can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements, and the person skilled in the art can understand the specific meaning of the present application according to the specific circumstances.

[0046] As shown in Figure 1 The standardized construction method of the steel core-UHPC composite box girder of the present embodiment includes the following steps:

[0047] S1, prefabricating a steel core 11 segment;

[0048] As shown in Figure 5 In the standardized construction method of the steel core-UHPC composite box girder of the present embodiment, before step S1 is implemented, construction preparation is also needed, which specifically includes the following steps:

[0049] The prefabricated box girder segment construction platform 4 and the pushing construction platform 5 are erected, the bottom formwork 2 is fixedly arranged on the prefabricated box girder segment construction platform 4, and when the demolding operation is performed, the bottom formwork 2 can be left on the prefabricated box girder segment construction platform 4 to facilitate the construction of the next segment of the prefabricated box girder 1, and the pushing construction platform 5 includes an electrically connected pushing control system and a steel guide beam 51. When a prefabricated box girder segment is completed, the pushing construction platform 5 directly performs the pushing construction.

[0050] The steel core-UHPC combined box girder made by the standardized construction method of the steel core-UHPC combined box girder of the embodiment is spliced by multiple prefabricated box girders 1. When one prefabricated box girder 1 is made, the prefabricated box girder 1 is driven to move forward by the steel guide beam 51 through the jacking control system, and then the next prefabricated box girder is made on the prefabricated box girder segment construction platform 4, and the two prefabricated box girders are connected, and the cycle is repeated until the whole bridge is jacked into place.

[0051] As shown in Figure 2 The steel core 11 is welded to form a box structure by a bottom plate, two webs and a top plate, and the bottom plate, the web and the top plate are steel plates of the same material. The inner side surface of the steel core 11 is provided with a steel transverse partition plate 112 for strengthening the strength of the steel core 11, thereby improving the overall and local strength of the steel core-UHPC combined box girder and preventing distortion. In this embodiment, the dowel 111 is welded on the steel plate. In other embodiments, the dowel 111 is welded on the outer surface of the formed steel core 11. The dowel 111 is used for positioning and fixing the binding of the web and top plate reinforcement, improving the construction quality and construction speed of the prefabricated box girder reinforcement cage.

[0052] S2: Hoist the steel core 11 above the bottom formwork 2.

[0053] In the standardized construction method of the steel core-UHPC combined box girder of the embodiment, the bottom plate reinforcement is bound on the prepared permanent bottom formwork 2. In other embodiments, the bottom plate reinforcement net can be directly hoisted into place after being bound on other sites. After the bottom plate reinforcement is bound on the bottom formwork 2, the steel core 11 is hoisted above the bottom formwork 2, and the gap between the steel core 11 and the bottom formwork 2 is the thickness of the bottom plate of the UHPC box girder 12. Since the bottom formwork 2 is fixed on the prefabricated box girder segment construction platform 4, when demolding is performed, the prefabricated box girder 1 can be jacked to the front through the jacking construction platform 5, so that the prefabricated box girder 1 and the bottom formwork 2 are demolded, and the bottom formwork 2 remains on the prefabricated box girder segment construction platform 4 for the construction of the next segment of the prefabricated box girder 1.

[0054] In the standardized construction method of the steel core-UHPC combined box girder of the embodiment, multiple attached vibrators 21 are arranged in an array below the bottom formwork. The attached vibrators are arranged in 1-2 columns according to the width of the bottom plate of the prefabricated box girder 1. The attached vibrators can accelerate the flow of the UHPC slurry on the bottom formwork 2.

[0055] S3: Weld the positioning reinforcement to the dowel 111 on the outer surface of the steel core 11, and then place and bind the reinforcement net.

[0056] After the steel inner core 11 is hoisted into position, the web and top steel bars are bound. The web and top steel bars are bound in situ with the aid of the pegs 111 on the surface of the steel inner core 11. The pegs 111 are used to position the steel bars. The steel bars are fixed at the appropriate positions by spot welding with the pegs 111 to form the positioning steel bars. Then, the steel mesh is placed and bound. This can not only accurately and effectively ensure the thickness of the steel protection layer, but also improve the construction efficiency.

[0057] S4: Install the side formwork 3 to the bottom formwork 2.

[0058] Since the steel inner core 11 can be directly used as the UHPC pouring inner form, only the pouring outer form needs to be erected during construction. The outer form mainly includes the bottom formwork 2 and the side formwork 3. The bottom formwork 2 is installed in position in advance during the construction preparation stage. After all the steel bars are bound, the side formwork 3 can be installed. The gap between the side formwork 3 and the steel inner core 11 is the web thickness of the UHPC box girder 12. The side formwork 3 needs to be fixed to prevent problems such as form rising and grout leakage during pouring. Like the bottom formwork 2, the side formwork 3 is a reusable form. In this embodiment, the side formwork 3 is fixedly installed to the bottom formwork 2 during use. In other embodiments, the side formwork 3 can be hinged to the bottom formwork 2. During use, the side formwork 3 is rotated to be perpendicular to the bottom formwork 2, and then the position of the side formwork 3 is fixed so that the gap between the side formwork 3 and the steel inner core 11 is the web thickness of the UHPC box girder 12. During demolding, the side formwork 3 is rotated by releasing the fixation, which makes it more convenient to disassemble and assemble the side formwork 3 and realizes recycling.

[0059] S5: Pour the UHPC slurry from one side of the side formwork 3 first. When the UHPC slurry flows through the bottom formwork 2 and reaches the other side of the side formwork 3 to a preset height, pour the UHPC slurry to both sides of the side formwork 3 simultaneously until the top UHPC slurry pouring is completed.

[0060] In the standardized construction method of the steel inner core-UHPC combined box girder in this embodiment, step S5 specifically includes:

[0061] S51: Pour the UHPC slurry from one side of the side formwork 3 first. When the UHPC slurry flows through the bottom formwork 2 and reaches the other side of the side formwork 3 to a preset height, pour the UHPC slurry to both sides of the side formwork 3 simultaneously until the top UHPC slurry pouring is completed.

[0062] For example, Figure 6As shown, the pouring is poured in the order of bottom plate-web-top plate. When pouring, first let the UHPC flow into the gap between the one side formwork 3 and the web of the steel inner core 11, and the UHPC slurry flows to the gap between the bottom formwork 2 and the bottom plate of the steel inner core 11 under the action of gravity. When the UHPC slurry overflows to the preset height from the gap between the other side formwork 3 and the web of the steel inner core 11, it indicates that the gap between the bottom formwork 2 and the bottom plate of the steel inner core 11 has been fully poured and compacted. At this time, the pouring can be carried out simultaneously from the gap between the two side formworks 3 and the steel inner core 11 to speed up the pouring speed. Because the UHPC web of the steel inner core-UHPC composite box girder is generally thin, in order to facilitate pouring, a pouring slot formwork 6 is arranged above the side formwork 3 in this embodiment. The pouring slot formwork 6 is a funnel with a wide upper part and a narrow lower part. When pouring, the inner wall is wetted with water to facilitate the flow of the slurry into the gap between the side formwork 3 and the web of the steel inner core 11. At the same time, in order to speed up the flow of the UHPC slurry in the gap between the bottom formwork 2 and the bottom plate of the steel inner core 11, the attached vibrator 21 below the bottom formwork 2 is turned on during pouring. After pouring is completed, the end face of the UHPC is flush with the end face of the steel inner core 11. For the composite box girder with thin wall characteristics, this way of pouring first one side and then two sides can ensure that the UHPC bottom plate is fully poured and compacted, and the construction quality of the structure is ensured.

[0063] S52: After pouring is completed, cover the UHPC box girder 12 with a thermal insulation cover 7, and use a temperature of 90-95°C for steam curing for a preset time.

[0064] After pouring is completed, the UHPC box girder 12 is as shown in Figure 3 As shown in Figure 4 Cover the UHPC box girder 12 with a thermal insulation cover 7, and then use 95°C for steam curing for 48h. This can fully develop the material strength and solve the problems of shrinkage and creep of the UHPC material in the later stage. In other embodiments, according to actual needs, steam curing at 90-95°C for any time can also be used.

[0065] S53: Perform chiseling treatment on the end part of the UHPC box girder 12.

[0066] Because the steel inner core-UHPC composite box girder is precast in segments, chiseling the UHPC at the end joint position of the UHPC box girder 12 can improve the stress performance of the joint.

[0067] S6: After the end part of the precast box girder 1 poured is completed is installed on the steel guide beam 51, push it forward, weld the steel inner core 11 of the next segment of the precast box girder 1 with the steel inner core 11 of the precast box girder 1 poured, and perform steps S2-S5 on the next segment of the precast box girder.

[0068] When a prefabricated box girder 1 is made, the prefabricated box girder 1 is driven forward by the steel guide beam 51 through the pushing control system, and then steps S2-S5 are performed on the prefabricated box girder segment construction platform 4 to make the next prefabricated box girder 1, and the two prefabricated box girders 1 are connected.

[0069] S7: Repeat step S5 until the whole bridge is pushed into place.

[0070] In the standardized construction method of the steel core-UHPC combined box girder of the embodiment, the binding of the web reinforcement and the top reinforcement of the UHPC can be positioned and fixed by means of the pegs 111 on the outer surface of the steel core 11, which is conducive to improving the construction quality and construction speed of the prefabricated box girder 1 reinforcement cage; the inner formwork is not needed during pouring of the prefabricated box girder 1, only the bottom formwork 2 and the side formwork 3 need to be installed, which simplifies the formwork engineering; for pouring of the UHPC, it is proposed to pour from one side of the side formwork 3 first, and then pour from both sides of the side formwork 3 when the UHPC slurry rises to the preset height on the other side of the side formwork 3, which can effectively ensure the pouring compactness requirement of the thin-walled plate of the prefabricated box girder 1 and improve the pouring quality of the thin-walled prefabricated box girder 1; the steel core-UHPC combined box girder standard segment prefabrication and pushing construction process of the embodiment effectively connects, fully guarantees the construction quality, and maximizes the inherent advantages of the steel core-UHPC combined box girder in the construction level, improves the construction efficiency of the bridge quality; the embodiment can eliminate the temporary pier and temporary prestressed cable used during pushing of the conventional concrete box girder, and realize the crossing of the concrete box girder pushing span of 60m~100m.

[0071] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A standardized construction method of a steel core-UHPC composite box girder, characterized in that, The method comprises the following steps: S1, prefabricating a steel inner core (11) segment; S2, hoisting the steel inner core (11) above a bottom formwork (2); S3, welding positioning steel bars to pegs (111) on the outer surface of the steel inner core (11), and then placing and binding a steel mesh; S4, installing side formworks (3) to the bottom formwork (2); S5, first pouring UHPC slurry from one side of the side formwork (3), and when the UHPC slurry flows through the bottom formwork (2) and reaches the other side of the side formwork (3) to a preset height, pouring UHPC slurry to both sides of the side formwork (3) simultaneously until the top UHPC slurry is poured to completion; S6, after the prefabricated box girder (1) is poured to completion, installing the end of the prefabricated box girder (1) to a steel guide beam (51) and pushing forward, welding the steel inner core (11) of the next prefabricated box girder (1) to the steel inner core (11) of the prefabricated box girder (1) poured to completion, and performing steps S2-S4 on the next prefabricated box girder; S7, repeating step S6 until the whole bridge is pushed into place.

2. The standardized construction method of a steel core-UHPC composite box girder according to claim 1, characterized in that, Between performing step S1, construction preparation is also needed, which specifically comprises the following steps: erecting a prefabricated box girder segment construction platform (4) and a pushing construction platform (5), fixing the bottom formwork (2) to the prefabricated box girder segment construction platform (4), and the pushing construction platform (5) comprising an electrically connected pushing control system and a steel guide beam (51), after one prefabricated box girder (1) is prefabricated, directly performing pushing construction by the pushing construction platform (5).

3. The standardized construction method of a steel core-UHPC composite box girder according to claim 1, characterized in that, The step S5 specifically comprises: S51, first pouring UHPC slurry from one side of the side formwork (3), and when the UHPC slurry flows through the bottom formwork (2) and reaches the other side of the side formwork (3) to a preset height, pouring UHPC slurry to both sides of the side formwork (3) simultaneously until the top UHPC slurry is poured to completion; S52, after pouring to completion, covering the UHPC box girder (12) with a thermal insulation quilt (7), and performing steam curing at a temperature of 90-95℃ for a preset time.

4. The standardized construction method of a steel core-UHPC composite box girder according to claim 3, characterized in that, The step S5 further comprises: S53, performing chiseling treatment on the end of the UHPC box girder (12).

5. The standardized construction method of a steel core-UHPC composite box girder according to claim 1, characterized in that, The steel inner core (11) is formed by welding steel plates, and a steel transverse partition plate (112) is arranged on the inner side of the steel inner core (11).

6. The standardized construction method of a steel core-UHPC composite box girder according to claim 5, characterized in that, The pegs (111) are welded on the steel plates or the outer surface of the formed steel inner core (11).

7. The standardized construction method of a steel core-UHPC composite box girder according to claim 1 or 2, characterized in that, The bottom formwork (2) is bound with bottom plate steel bars.

8. The standardized construction method of a steel core-UHPC composite box girder according to claim 1 or 2, characterized in that, A plurality of attached vibrators (21) are arranged in an array below the bottom formwork (2).

9. The standardized construction method of a steel core-UHPC composite box girder according to claim 1 or 2, characterized in that, When pouring the bottom plate and web of the UHPC box girder (12), a pouring opening slot formwork (6) is arranged above the side formwork (3).

10. The standardized construction method of a steel core-UHPC composite box girder according to claim 1 or 2, characterized in that, The bottom formwork (2) and the side formwork (3) are both reusable formworks.

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