CN112921805A - Assembled steel-coconut fiber magnesium phosphate cement bridge deck composite beam and construction method - Google Patents

Abstract

The invention discloses an assembled steel-coconut fiber magnesium phosphate cement bridge deck composite beam and a construction method, wherein the composite beam comprises at least two sections of bridge units, each bridge unit comprises a steel beam and a bridge deck, a stiffening steel box is welded on the lower edge part of each steel beam beside a fulcrum, a stiffening rib is welded on the end part of each steel beam, and a first bolt hole is reserved in each stiffening rib; the bridge deck comprises a coconut fiber-magnesium phosphate cement board and a reinforced concrete slab which are cast in place, the coconut fiber-magnesium phosphate cement board is laid at the sections above the fixed support, the reinforced concrete slab is arranged at the other sections, the coconut fiber-magnesium phosphate cement board and the reinforced concrete slab are connected through prestressed fine-rolled threaded steel bars, and a second bolt hole is formed in the top of the steel beam. The coconut fiber-magnesium phosphate cement board poured in site is used for resisting the tensile stress of the hogging moment area of the continuous beam, the compressive capacity of the lower edge of the steel beam is improved by welding the stiffening steel box, the prefabrication and cast-in-place are combined, the assembly is integral, the standardization degree is high, and the construction operation is fast.

Description

Assembled steel-coconut fiber magnesium phosphate cement bridge deck composite beam and construction method

Technical Field

The invention relates to the technical field of bridge engineering, in particular to an assembled steel-coconut fiber magnesium phosphate cement bridge deck composite beam and a construction method thereof.

Background

According to incomplete detection and statistics of the road and bridge, the current vehicle overload phenomenon is increasingly serious, the over-limit vehicles account for more than 57% of daily average traffic volume, and the vehicles accounting for more than 30t of total weight account for 15%, which indicates that the over-limit vehicles greatly exceed the load of the road and bridge, so that the bearing structure of the bridge is damaged, and the bridge structure and the driving safety are endangered. The existing highway bridges in China are built in different periods, most of the highway bridges are long-lived, the quality of building materials is backward, the designed load level is low, engineering technology is backward, the bearing capacity is insufficient, and many bridges cannot meet the requirements of large traffic at present and are in a bridge-endangering state. Aiming at the situation, in recent 20 years, the engineering world mostly adopts methods of widening and rebuilding old bridges to solve the problems, but the methods inevitably have the problems of reasonable evaluation and reasonable utilization of existing bridges and culverts and splicing of new and old bridges, and have the disadvantages of long bridge construction period, high technical difficulty, high operation difficulty and great influence on traffic and environment along the line.

Since the 21 st century, in the urban bridge construction, in order to avoid the defects generated by the traditional construction method, the prefabrication and assembly construction technology is widely applied because the construction period can be effectively shortened, the construction quality is improved, and the urban environmental pollution is reduced. However, the division of prefabricated structural sections, the design of joints between sections, and how to fully utilize the performance of new materials to improve the quality and durability of prefabricated bridges are obviously problems that need to be solved urgently.

The traditional fabricated composite beam adopts a single type of reinforced concrete slab when the bridge deck slab is prefabricated, which is not favorable for the stress requirements of different parts of the continuous beam along the length direction. The traditional common concrete prefabricated part has the problems of low strength, poor tensile property, long maintenance time and the like. The UHPC ultrahigh-performance concrete slab is inconvenient to prefabricate, and has the problems of harsh steam curing conditions, high curing cost and the like. The toughness and crack resistance of magnesium phosphate cement are improved by adding fiber materials, but the conventional artificial fiber is expensive and causes huge energy consumption in production and treatment.

Disclosure of Invention

The invention aims to solve at least one of the technical problems in the prior art and provides an assembled steel-coconut fiber magnesium phosphate cement bridge deck composite beam and a construction method thereof.

The technical scheme adopted by the invention is as follows: an assembled steel-coconut fiber magnesium phosphate cement bridge deck slab combination beam comprises at least two sections of bridge units, wherein each bridge unit comprises a plurality of steel beams and a bridge deck, the steel beams are variable-section steel beams, stiffening steel boxes are welded on the lower edge parts of the steel beams beside supporting points, stiffening ribs are welded at the end parts of the steel beams, first bolt holes are reserved in the stiffening ribs, and adjacent steel beams are fixedly connected through first high-strength bolts through the first bolt holes; the bridge floor includes cast-in-place coconut fibre-magnesium phosphate cement board and prefabricated reinforced concrete slab, and the bridge floor setting is in the girder steel top, coconut fibre-magnesium phosphate cement board is laid in the festival section department that is located the fixing support top, and all the other festival section departments all set up reinforced concrete slab, coconut fibre-magnesium phosphate cement board with reinforced concrete slab is through prestressing force finish-tie threaded steel bar connection, the girder steel top is provided with the second bolt hole, the bridge floor passes second bolt hole and girder steel fastening connection through second high strength bolt.

Has the advantages that: the assembled steel-coconut fiber magnesium phosphate cement bridge deck slab combination beam resists the tensile stress of a hogging moment area of a continuous beam by utilizing the coconut fiber-magnesium phosphate cement board poured in situ, improves the compressive capacity of the lower edge of a steel beam by welding the stiffening steel box, and has the advantages of combination of prefabrication and cast-in-place, integral assembly, high standardization degree and quick site construction operation.

Furthermore, the steel beam is welded with a web plate reinforcing rib.

Further, the lower end of the joint of two adjacent steel beams is welded with a cover plate.

Furthermore, reserved notches are formed between the stiffening steel box and the stiffening ribs.

Further, the asphalt pavement is poured on the bridge deck slab, and the guardrail is installed.

A construction method of an assembly type steel-coconut fiber magnesium phosphate cement bridge deck slab combination beam comprises the following steps:

s1, manufacturing a variable cross-section steel beam: selecting a proper steel beam according to the span size, the load grade and the section steel specification, arranging second bolt holes according to the design requirement, welding a stiffening steel box on the lower edge part of the steel beam, welding stiffening ribs on the end part of the steel beam, and presetting first bolt holes on the stiffening ribs;

s2, prefabricating a reinforced concrete plate, reserving a through hole for the second high-strength bolt to pass through on the reinforced concrete plate, and storing the reinforced concrete plate for at least 3 months after prefabrication so as to basically finish the shrinkage and creep of the concrete;

s3, transporting the welded steel beams to the site, firstly hoisting the steel beams one by a crane in a span-by-span mode to form a steel structure simple supported beam, then fastening first high-strength bolts of the steel beam stiffening ribs to form a steel structure continuous beam, and finally welding a cover plate of a stiffening area at the lower edge of the node after all the steel beams are assembled to form an integral outer steel plate;

s4, casting a bridge deck in situ: hoisting the bridge deck slab piece by piece, wherein common reinforced concrete slabs are used above other steel beams except for a single continuous coconut fiber-magnesium phosphate cement slab above the fixed support, the coconut fiber-magnesium phosphate cement slab is poured on site according to actual size and specification, and then a second high-strength bolt between the bridge deck slab and the steel beam is fastened;

and S5, pouring asphalt pavements and installing guardrails on the bridge deck slab, and completing construction.

Further, in step S1, web reinforcing ribs are welded to the steel beam.

Drawings

The invention is further illustrated with reference to the following figures and examples:

FIG. 1 is a drawing illustrating an elevation structure of an 1/2 bridge beam with 3 spans of simple-support-to-continuous composite beams in the present embodiment;

FIG. 2 is a schematic cross-sectional view taken along line A-A of FIG. 1;

FIG. 3 is a schematic view of a welded monolithic steel beam structure;

FIG. 4 is a schematic diagram of the first span steel beam after being hoisted in place;

FIG. 5 is a schematic view of the second span steel beam being hoisted in place;

FIG. 6 is a schematic view of hoisting a third span steel beam and welding a cover plate;

FIG. 7 is a schematic view of a suspended bridge deck;

FIG. 8 is a schematic view of the bridge deck pavement.

Description of reference numerals: the steel beam-1, the stiffening steel box-11, the stiffening rib-12, the first bolt hole-121, the first high-strength bolt-13, the second bolt hole-14, the coconut fiber-magnesium phosphate cement board 21, the reinforced concrete board-22, the second high-strength bolt-23, the fixed support-3, the cover board-4, the reserved notch-5 and the asphalt pavement-6.

Detailed Description

Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.

Referring to fig. 1 to 8, embodiments of the present invention provide a novel assembled steel-coconut fiber magnesium phosphate cement bridge deck composite beam. Specifically, fig. 1 is a schematic structural diagram of a 3-span simply supported-to-continuous composite beam formed by using the present invention. The composite beam comprises three sections of beam spanning units, each beam spanning unit comprises a plurality of steel beams 1 and a bridge deck, the steel beams 1 are variable-section steel beams, and stiffening steel boxes 11 are welded on the lower edge portions of the steel beams 1 beside fulcrums, so that the compression stability is enhanced. Stiffening ribs 12 are welded at the end parts of the steel beams 1, first bolt holes 121 are reserved in the stiffening ribs 12, and the adjacent steel beams 1 are fixedly connected through first high-strength bolts 13 penetrating through the first bolt holes 121; the bridge floor comprises a cast-in-place coconut fiber-magnesium phosphate cement board 21 and prefabricated reinforced concrete slabs 22, the bridge floor is arranged above the steel beam 1, the coconut fiber-magnesium phosphate cement board 21 is laid at a section above the fixed support 3, the reinforced concrete slabs 22 are arranged at the rest sections, the coconut fiber-magnesium phosphate cement board 21 and the reinforced concrete slabs 22 are connected through prestressed fine-rolled threaded steel bars, a second bolt hole 14 is formed in the top of the steel beam 1, and the bridge floor penetrates through the second bolt hole 14 through a second high-strength bolt 23 to be fixedly connected with the steel beam 1.

The assembled steel-coconut fiber magnesium phosphate cement bridge deck slab combination beam resists the tensile stress of a hogging moment area of a continuous beam by utilizing the coconut fiber-magnesium phosphate cement boards 21 poured in situ, improves the compressive capacity of the lower edge of the steel beam 1 by welding the stiffening steel box 11, and has the advantages of combining prefabrication and cast-in-place, high assembly integrity and standardization degree and quick site construction operation.

Preferably, in order to further enhance the strength of the steel beam 1, web reinforcing ribs are welded on the steel beam 1.

Further, in order to integrate the outer steel plates, a cover plate 4 is welded to the lower end of the joint of two adjacent steel beams 1.

Preferably, the bridge deck is cast with asphalt pavement 6 and installed with guardrails.

Reserved notches 5 are formed between the stiffening steel box 11 and the stiffening ribs 12, and installation of the first high-strength bolts 13 is facilitated.

The construction method of the assembled steel-coconut fiber magnesium phosphate cement bridge deck slab combination beam comprises the following steps:

s1, manufacturing a variable cross-section steel beam 1: selecting a proper steel beam 1 according to the span size, the load grade and the section steel specification, arranging second bolt holes 14 according to the design requirement, welding a stiffening steel box 11 on the lower edge part of the steel beam 1, welding stiffening ribs 12 on the end parts of the steel beam 1, and presetting first bolt holes 121 on the stiffening ribs 12; meanwhile, web reinforcing ribs are welded on the steel beam 1 so as to further improve the strength of the steel beam 1;

s2, prefabricating the reinforced concrete slab 22, reserving a through hole for the second high-strength bolt 23 to penetrate through on the reinforced concrete slab 22, and storing the reinforced concrete slab 22 for at least 3 months after prefabrication is completed so that shrinkage and creep of concrete are basically completed;

s3, transporting the welded steel beams 1 to the site, firstly, hoisting the steel beams 1 one by using a crane to form a steel structure simple supported beam, then fastening the first high-strength bolts 13 of the stiffening ribs 12 to form a steel structure continuous beam, and finally, after all the steel beams 1 are assembled, welding the cover plate 4 of the stiffening area at the lower edge of the node to form an outer steel plate into a whole;

s4, casting a bridge deck in situ: hoisting the bridge deck slab piece by piece, using common reinforced concrete slabs 22 above other steel beams 1 except for a single continuous coconut fiber-magnesium phosphate cement slab 21 above the fixed support 3, pouring the coconut fiber-magnesium phosphate cement slab 21 on site according to actual size and specification requirements, and then fastening second high-strength bolts 23 between the bridge deck slab and the steel beams 1;

and S5, pouring the asphalt pavement 6 on the bridge deck slab, and installing the guardrail, so as to finish the construction.

Therefore, in the assembled steel-coconut fiber magnesium phosphate cement bridge deck composite beam, the sections near the pivot are coconut fiber-magnesium phosphate cement boards 21, and the other sections are common reinforced concrete boards 22, so that a multi-plate composite bridge deck is formed, and the requirements of the steel-concrete composite continuous beam on stress of different parts along the length direction are met. The cast-in-situ coconut fiber-magnesium phosphate cement board 21 is adopted, so that the performances of the two materials are fully exerted, the compressive strength is high, and the tensile performance is good. Meanwhile, the coconut fiber-magnesium phosphate cement board 21 is simple and convenient to operate, does not need steam curing, is short in curing time, and is beneficial to rapid preparation and later-period replacement. The toughness and crack resistance of the magnesium phosphate cement are improved by replacing artificial fiber with cheap, degradable and renewable coconut fiber, and the magnesium phosphate cement has the advantage of green sustainable development.

The bridge deck is formed by combining the coconut fiber-magnesium phosphate cement board 21 and the reinforced concrete board 22, so that the requirements of the steel-concrete combined continuous beam on stress at different positions along the length direction can be met, the characteristics of different materials are fully utilized, and the construction cost is reduced; end stiffeners 12, fulcrum-stiffened steel boxes 11, and the like, bridge span connections and a structure for preventing buckling.

Compared with the traditional steel-concrete assembled composite beam bridge, the bridge deck plate realizes section division in the bridge span direction through construction joints in the transverse bridge direction, adopts the coconut fiber-magnesium phosphate cement plate 21 in the hogging moment area, and adopts the common reinforced concrete plate 22 in the other sections, thereby fully playing the excellent performances of the two bridge deck plates and effectively improving the problem that the hogging moment area of the continuous composite beam is unfavorable in stress; meanwhile, a stiffening box is welded on the lower edge of the steel beam 1, so that the pressure resistance of the lower edge is improved. Compared with the traditional ultrahigh-performance concrete, the coconut fiber-magnesium phosphate cement material has the advantages of short setting time, high volume stability, good wear resistance, good toughness and the like, so that the mode of combining factory prefabrication and partial cast-in-place is adopted, the high efficiency and the rapidness of field construction are ensured, and the integrity, the safety and the reliability of an assembled structure are improved.

While the embodiments of the present invention have been described in detail with reference to the drawings, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.

Claims (7)

1. The utility model provides an assembled steel-coconut fibre magnesium phosphate cement decking composite beam which characterized in that: the cross beam comprises at least two sections of cross beam units, each cross beam unit comprises a plurality of steel beams and a bridge deck, the steel beams are variable-section steel beams, stiffening steel boxes are welded on the lower edge portions of the steel beams beside supporting points, stiffening ribs are welded on the end portions of the steel beams, first bolt holes are reserved in the stiffening ribs, and the adjacent steel beams are fixedly connected through the first bolt holes through first high-strength bolts; the bridge floor includes cast-in-place coconut fibre-magnesium phosphate cement board and prefabricated reinforced concrete slab, and the bridge floor setting is in the girder steel top, coconut fibre-magnesium phosphate cement board is laid in the festival section department that is located the fixing support top, and all the other festival section departments all set up reinforced concrete slab, coconut fibre-magnesium phosphate cement board with reinforced concrete slab is through prestressing force finish-tie threaded steel bar connection, the girder steel top is provided with the second bolt hole, the bridge floor passes second bolt hole and girder steel fastening connection through second high strength bolt.

2. The assembled steel-coconut fiber magnesium phosphate cement bridge deck composite beam of claim 1, wherein: the steel beam is welded with a web plate reinforcing rib.

3. The assembled steel-coconut fiber magnesium phosphate cement bridge deck composite beam of claim 1, wherein: the lower end part of the joint of the two adjacent steel beams is welded with a cover plate.

4. The assembled steel-coconut fiber magnesium phosphate cement bridge deck composite beam of claim 1, wherein: and reserved notches are formed between the stiffening steel box and the stiffening ribs.

5. The assembled steel-coconut fiber magnesium phosphate cement bridge deck composite beam as claimed in any one of claims 1 to 4, wherein: and an asphalt pavement is poured on the bridge deck slab, and a guardrail is installed on the bridge deck slab.

6. A construction method of an assembly type steel-coconut fiber magnesium phosphate cement bridge deck slab combination beam is characterized by comprising the following steps:

s1, manufacturing a variable cross-section steel beam: selecting a proper steel beam according to the span size, the load grade and the section steel specification, arranging second bolt holes according to the design requirement, welding a stiffening steel box on the lower edge part of the steel beam, welding stiffening ribs on the end part of the steel beam, and presetting first bolt holes on the stiffening ribs;

s2, prefabricating a reinforced concrete plate, reserving a through hole for the second high-strength bolt to pass through on the reinforced concrete plate, and storing the reinforced concrete plate for at least 3 months after prefabrication so as to basically finish the shrinkage and creep of the concrete;

s3, transporting the welded steel beams to the site, firstly hoisting the steel beams one by a crane in a span-by-span mode to form a steel structure simple supported beam, then fastening first high-strength bolts of the steel beam stiffening ribs to form a steel structure continuous beam, and finally welding a cover plate of a stiffening area at the lower edge of the node after all the steel beams are assembled to form an integral outer steel plate;

s4, casting a bridge deck in situ: hoisting the bridge deck slab piece by piece, wherein common reinforced concrete slabs are used above other steel beams except for a single continuous coconut fiber-magnesium phosphate cement slab above the fixed support, the coconut fiber-magnesium phosphate cement slab is poured on site according to actual size and specification, and then a second high-strength bolt between the bridge deck slab and the steel beam is fastened;

and S5, pouring asphalt pavements and installing guardrails on the bridge deck slab, and completing construction.

7. The construction method according to claim 6, wherein: in step S1, web reinforcing ribs are welded to the steel beam.

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