Hot-rolled T-shaped steel-UHPC fabricated pi-shaped composite beam and construction method thereof

Abstract

The invention provides a hot-rolled T-shaped steel-UHPC fabricated pi-shaped composite beam and a construction method thereof. The hot-rolled T-shaped steel-UHPC fabricated pi-shaped composite beam comprises two longitudinal beams, a plurality of transverse partition plates and a UHPC bridge deck slab. The two longitudinal beams are vertically arranged in parallel in a spaced mode, and each longitudinal beam is jointly composed of two pieces of hot-rolled T-shaped steel and UHPC, wherein the two pieces of hot-rolled T-shaped steel are symmetrically arranged up and down, and the outer peripheral sides of the hot-rolled T-shaped steel are wrapped with the UHPC. The transverse partition plates are vertically arranged in parallel at intervals, and the two side ends of each transverse partition plate are perpendicularly connected between the side walls of the two longitudinal beams respectively. The UHPC bridge deck slab is installed on the tops of the two longitudinal beams and the tops of the transverse partition plates, and a plurality of load-bearing steel bars are evenly arranged in the UHPC bridge deck slab in the longitudinal direction and the transverse direction at intervals. According to the structure, different beam heights are formed through the hot-rolled T-shaped steel and the UHPC of existing specifications, the structure can adapt to combination beams of different spans, the high-strength compression resistance of the UHPC and the high tensile property of the T-shaped steel are brought into full play, and the structure has the advantages of being good in durability, high in adaptability, good in stress performance, high in bearing capacity and capable of being prefabricated and assembled.

Description

Technical Field

[0001] The present application relates to the field of bridges, and particularly to a hot-rolled T-shaped steel-UHPC assembled π-shaped composite beam and its construction method. Background Art

[0002] Since steel-concrete composite beams can give full play to the material advantages of high tensile strength and good ductility of steel and high compressive strength and large stiffness of concrete, they are increasingly widely used in bridge engineering. However, the existing steel-concrete composite beams mainly have the following problems in the application process:

[0003] (1) Although the method of welding steel plates can be used for bridge structures with large spans, the weld between the flange plate and the web becomes the weak stress area of the whole structure. At the same time, the weld also has fatigue problems, affecting the structural safety;

[0004] (2) In recent years, there have also been a small number of cases using existing standard rolled steel sections to replace welded steel plates. However, limited by rolling technology, the overall beam height can only be applicable to small-span bridge structures, and the connection between the steel section and the concrete still uses traditional shear studs, which also have problems such as large welding work quantity and welding quality;

[0005] (3) Most of the conventional steel-concrete composite beams adopt on-site construction or partial prefabrication + on-site construction and other methods, which have problems such as uncontrollable on-site welding quality, difficult on-site construction, long construction period, and low industrialization level; at the same time, for continuous beam structures, the cracking problem in the negative moment area of the conventional steel-concrete composite beam is particularly prominent. Summary of the Invention

[0006] One of the purposes of the present application is to provide a hot-rolled T-shaped steel-UHPC assembled π-shaped composite beam and its construction method, aiming to solve the problem of poor quality of the existing steel-concrete composite beam.

[0007] The technical solution of the present application is as follows:

[0008] A hot-rolled T-shaped steel-UHPC assembled π-shaped composite beam includes two longitudinal beams, multiple transverse diaphragms, and a UHPC bridge deck; the two longitudinal beams are vertically arranged in parallel at intervals, and each longitudinal beam is jointly composed of two hot-rolled T-shaped steels arranged symmetrically up and down and UHPC concrete wrapped around the outer peripheral side of the hot-rolled T-shaped steel; the multiple transverse diaphragms are all vertically arranged in parallel at intervals, and both ends of each transverse diaphragm are respectively vertically connected between the side walls of the two longitudinal beams; the UHPC bridge deck is installed on the tops of the two longitudinal beams and the multiple transverse diaphragms, and multiple stress bars are respectively arranged at uniform intervals longitudinally and transversely inside the UHPC bridge deck.

[0009] As a technical solution of the present application, the UHPC bridge deck is formed by jointly pouring UHPC concrete and multiple stress-bearing steel bars.

[0010] As a technical solution of the present application, both ends of multiple stress-bearing steel bars arranged transversely inside the UHPC bridge deck extend out of both sides of the UHPC bridge deck.

[0011] As a technical solution of the present application, multiple support steel bars and multiple U-shaped steel bars are arranged inside each longitudinal beam; the support steel bars are sequentially arranged at intervals from bottom to top along the height direction of the longitudinal beam; the U-shaped steel bars are sequentially arranged at intervals along the length direction of the longitudinal beam, and the lower part of the U-shaped steel bar passes through the web of the hot-rolled T-shaped steel at the lower part of the longitudinal beam, and the upper part passes through the flange plate of the hot-rolled T-shaped steel at the upper part of the longitudinal beam and extends into the UHPC bridge deck.

[0012] As a technical solution of the present application, multiple first connection holes are arranged at intervals along the length direction on the web of the hot-rolled T-shaped steel at the lower part of the longitudinal beam, and multiple second connection holes are arranged at intervals along the length direction on the flange plate of the hot-rolled T-shaped steel at the upper part of the longitudinal beam, and both ends of the U-shaped steel bar are respectively connected to the first connection hole and the second connection hole.

[0013] As a technical solution of the present application, the total width of the UHPC concrete is equal to the width of the flange plate of the hot-rolled T-shaped steel.

[0014] As a technical solution of the present application, the layout spacing of the cross diaphragms is 5 - 8 m.

[0015] As a technical solution of the present application, the cross diaphragm is formed by jointly pouring multiple transverse steel bars, multiple vertical steel bars and UHPC concrete.

[0016] As a technical solution of the present application, multiple transverse steel bars are sequentially arranged parallel and at intervals along the height direction of the cross diaphragm inside the cross diaphragm, and both ends respectively extend into the longitudinal beams on both sides; multiple vertical steel bars are sequentially arranged parallel and at intervals along the length direction of the cross diaphragm inside the cross diaphragm, and the top ends extend into the UHPC bridge deck.

[0017] A construction method for a hot-rolled T-shaped steel - UHPC assembled π-shaped composite beam includes the following steps:

[0018] S1. Select hot-rolled T-shaped steel that meets the design requirements according to the actual bridge span and width, and perforate the web and flange plates of the hot-rolled T-shaped steel respectively according to the design requirements; adjust the spacing of the symmetrically arranged hot-rolled T-shaped steel in the height direction according to the actual beam height and fix it with temporary supports.

[0019] S2. Bind the support steel bars and U-shaped steel bars inside the longitudinal beam; bind the transverse steel bars and vertical steel bars inside the diaphragm; fabricate and install the side formwork of the longitudinal beam, the bottom formwork and side formwork of the diaphragm, and the formwork of the UHPC bridge deck; bind the longitudinal and transverse stress steel bars inside the UHPC bridge deck.

[0020] S3. Pour the UHPC concrete wrapped around both sides of the web of the hot-rolled T-shaped steel, the diaphragm and the UHPC bridge deck, and remove the formwork and temporary fixing support members after curing to the design strength; a combined beam of a standard segment is formed by the longitudinal beam, the diaphragm and the UHPC bridge deck, and the transverse wet joint position between segments is reserved according to the actual situation during this process.

[0021] S4. Transport the prefabricated combined beam of the standard segment to the construction site, hoist the combined beam of the standard segment to the designated position for assembly construction; after all the combined beams in the transverse direction are installed in place, bind the longitudinal reinforcement bars at the reserved transverse wet joint position and pour UHPC concrete to make all the combined beams of the standard segments form an integral whole.

[0022] Advantages of the present application:

[0023] (1) In the hot-rolled T-shaped steel-UHPC assembled π-shaped combined beam of the present application, by wrapping UHPC concrete around both sides of the web of the hot-rolled T-shaped steel, the durability of the steel is enhanced, and for structures with a relatively high beam height, the stability of the longitudinal beam web under compression is improved; at the same time, by adopting hot-rolled T-shaped steel and UHPC bridge deck arranged symmetrically at the top and bottom, problems such as excessive negative bending moment in the continuous beam and excessive bearing shear force can be effectively solved.

[0024] (2) In the construction method of the hot-rolled T-shaped steel-UHPC assembled π-shaped combined beam of the present application, by using rolled steel instead of welded steel plates and making U-shaped steel bars extend into the UHPC bridge deck through perforation instead of shear studs, zero-weld construction is basically achieved, avoiding the influence of weld fatigue problems on structural safety. At the same time, compared with conventional welding, the welding workload is reduced, energy consumption and carbon emissions are reduced, which conforms to the current green, low-carbon and industrialized design concept; moreover, its structural layout form is flexible and changeable. By changing parameters such as the section steel specification, the spacing in the height direction and the transverse spacing of the longitudinal beam, it can meet the requirements of bridges with different spans and widths. At the same time, it has a high degree of prefabrication and fast construction, and has broad application prospects. Description of the Drawings

[0025] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for the embodiments will be briefly introduced below. It should be understood that the following accompanying drawings only show some embodiments of the present application, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related accompanying drawings can also be obtained based on these drawings.

[0026] Figure 1 Schematic diagram of a hot-rolled T-shaped steel - UHPC prefabricated π-shaped composite beam provided by the first embodiment of the present application;

[0027] Figure 2 Schematic diagram of a longitudinal beam provided by the first embodiment of the present application;

[0028] Figure 3 First-angle schematic diagram of a hot-rolled T-shaped steel - UHPC prefabricated π-shaped composite beam provided by the first embodiment of the present application;

[0029] Figure 4 Partial schematic diagram of a hot-rolled T-shaped steel - UHPC prefabricated π-shaped composite beam provided by the first embodiment of the present application;

[0030] Figure 5 Assembly schematic diagram of a hot-rolled T-shaped steel - UHPC prefabricated π-shaped composite beam provided by the first embodiment of the present application.

[0031] Icons: 1 - Hot-rolled T-shaped steel; 2 - UHPC bridge deck; 3 - Diaphragm; 4 - Stress reinforcement; 5 - U-shaped steel bar; 6 - Support reinforcement; 7 - UHPC concrete; 8 - First connection hole; 9 - Second connection hole; 10 - Vertical reinforcement; 11 - Wet joint. Detailed implementation manners

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and shown in the accompanying drawings here can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0034] It should be noted that like reference numerals and letters refer to like items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0035] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper", "lower", etc. is based on the orientation or positional relationship shown in the figures, or the orientation or positional relationship in which the inventive product is customarily placed during use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0036] In addition, in the present application, unless otherwise clearly specified and defined, the first feature being above or below the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being above, over, and on the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being below, under, and beneath the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0037] In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging, but may be slightly inclined. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but may be slightly inclined.

[0038] In the description of the present application, it should also be noted that, unless otherwise clearly specified and defined, the terms "arranged", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0039] First Embodiment:

[0040] Please refer to Figure 1 and, in conjunction with reference to Figures 2 to 5, this application provides a hot-rolled T-shaped steel 1-UHPC assembled π-shaped composite beam, which mainly includes two longitudinal beams, multiple transverse diaphragms 3 and a UHPC bridge deck 2; among them, the two longitudinal beams are vertically arranged in parallel at intervals, and each longitudinal beam is jointly composed of two hot-rolled T-shaped steels 1 arranged symmetrically up and down and UHPC concrete 7 wrapped around the outer peripheral side of the hot-rolled T-shaped steel 1; at the same time, multiple transverse diaphragms 3 are all vertically arranged in parallel at intervals, and both ends of each transverse diaphragm 3 are respectively vertically connected between the side walls of the two longitudinal beams; in addition, the UHPC bridge deck 2 is installed on the tops of the two longitudinal beams and multiple transverse diaphragms 3, and multiple stress-bearing steel bars 4 are evenly arranged at intervals in the longitudinal and transverse directions inside the UHPC bridge deck 2. The π-shaped composite beam is composed of the above-mentioned UHPC bridge deck 2, longitudinal beams and transverse diaphragms 3, and the upper structure of the bridge is composed of several π-shaped composite beams spliced horizontally. Therefore, this structure forms composite beams with different beam heights and different spans through existing specifications of hot-rolled T-shaped steel 1 and UHPC, giving full play to the high compressive strength of UHPC and the high tensile strength of T-shaped steel, and having the characteristics of good durability, strong adaptability, good mechanical properties, high load-bearing capacity, no need for welding, prefabricable and assembled, and fast construction. Moreover, the longitudinal beam composed of the UHPC bridge deck 2, hot-rolled T-shaped steel 1 and the outer UHPC concrete 7, and the composite beam structure jointly formed by the transversely arranged transverse diaphragms 3 can not only give full play to the material advantages of high tensile strength and good ductility of steel and high compressive strength and large stiffness of concrete, but also be constructed in a fully prefabricated and assembled manner, with the advantages of light self-weight, zero welds, low energy consumption, and flexible and variable structural forms.

[0041] Furthermore, the UHPC bridge deck 2 is formed by jointly pouring UHPC concrete and multiple stress-bearing steel bars 4. And both ends of the multiple stress-bearing steel bars 4 in the transverse direction inside the UHPC bridge deck 2 extend out a certain length on both sides of the UHPC bridge deck 2, which is convenient for the wet joint 11 of the on-site construction in the later stage.

[0042] Meanwhile, the height of the longitudinal beam can be adjusted to meet the requirements of bridges with different spans and widths by changing parameters such as the specifications of the hot-rolled T-shaped steel 1, the spacing in the height direction, and the transverse spacing of the longitudinal beams. The structural layout form is flexible and changeable, with a high degree of prefabrication and fast construction, presenting broad application prospects. The hot-rolled T-shaped steel 1 can be fabricated using different specifications of T-shaped steel according to the width and span of the bridge. Inside each longitudinal beam, multiple support steel bars 6 and multiple U-shaped steel bars 5 are arranged. The support steel bars 6 are sequentially and spacedly arranged from bottom to top along the height direction of the longitudinal beam; the U-shaped steel bars 5 are sequentially and spacedly arranged along the length direction of the longitudinal beam, and the lower part of the U-shaped steel bar 5 passes through the web of the hot-rolled T-shaped steel 1 at the lower part of the longitudinal beam, and the upper part passes through the flange plate of the hot-rolled T-shaped steel 1 at the upper part of the longitudinal beam and extends into the UHPC bridge deck 2. UHPC concrete 7 is wrapped around both sides of the web of the hot-rolled T-shaped steel 1 to enhance the connection strength and integrity between the hot-rolled T-shaped steel 1 and the wrapped UHPC concrete 7, as well as between the longitudinal beam and the UHPC bridge deck 2. In addition, a plurality of first connection holes 8 spaced along the length direction are provided on the web of the hot-rolled T-shaped steel 1 at the lower part of the longitudinal beam, and a plurality of second connection holes 9 spaced along the length direction are provided on the flange plate of the hot-rolled T-shaped steel 1 at the upper part of the longitudinal beam. The two ends of the U-shaped steel bar 5 are respectively connected to the first connection hole 8 and the second connection hole 9. The diameters of the first connection hole 8 and the second connection hole 9 can be determined according to the size of the force-reinforcing bars in different bridge structures, and it is ensured that the diameters of the first connection hole 8 and the second connection hole 9 are slightly larger than the diameter of the U-shaped steel bar 5.

[0043] It should be noted that the total width of the UHPC concrete 7 is equal to the width of the flange plate of the hot-rolled T-shaped steel 1.

[0044] Moreover, by wrapping UHPC concrete 7 around both sides of the web of the hot-rolled T-shaped steel 1, the durability of the steel is enhanced, and for structures with a relatively high beam height, the stability of the longitudinal beam web under compression is improved; in addition, the problem of excessive negative bending moment in the continuous beam and excessive shear force at the support can be effectively solved by symmetrically arranging the hot-rolled T-shaped steel 1 and the UHPC bridge deck 2 at the top and bottom; using rolled T-shaped steel instead of welded steel plates, and enabling the U-shaped steel bar 5 to extend into the UHPC bridge deck 2 through the holes instead of shear studs, basically realizes zero-weld construction, avoiding the impact of weld fatigue problems on structural safety. At the same time, compared with conventional welding, the welding workload is reduced, energy consumption and carbon emissions are reduced, meeting the current green, low-carbon, and industrialized design concepts.

[0045] Furthermore, the layout spacing of the diaphragm 3 is 5 - 8 m. And the diaphragm 3 is formed by jointly pouring multiple transverse steel bars, multiple vertical steel bars 10, and UHPC concrete 7. Among them, the multiple transverse steel bars are arranged parallel and at intervals along the height direction of the diaphragm 3 inside the diaphragm 3, and both ends extend into the longitudinal beams on both sides respectively; the multiple vertical steel bars 10 are arranged parallel and at intervals along the length direction of the diaphragm 3 inside the diaphragm 3, and the tops extend into the UHPC bridge deck 2 to enhance the connection strength between the diaphragm 3 and the longitudinal beams and the UHPC bridge deck 2, thereby improving the integrity of the hot-rolled T-shaped steel 1 - UHPC assembled π-shaped composite beam.

[0046] To sum up, in the hot-rolled T-shaped steel 1 - UHPC assembled π-shaped composite beam of the present application, by wrapping UHPC concrete 7 on both sides of the web of the hot-rolled T-shaped steel 1, the durability of the steel is enhanced, and for structures with a relatively high beam height, the stability of the longitudinal beam web under compression is improved; at the same time, by adopting the hot-rolled T-shaped steel 1 and the UHPC bridge deck 2 arranged symmetrically at the top and bottom, problems such as excessive negative bending moment in the continuous beam and excessive shear force at the support can be effectively solved. At the same time, it uses rolled steel instead of welded steel plates, and through the opening, the U-shaped steel bars 5 are extended into the UHPC bridge deck 2 to replace the shear studs, basically realizing zero-weld construction, avoiding the influence of weld fatigue problems on the structural safety, and at the same time reducing the welding workload compared with conventional welding, reducing energy consumption and carbon emissions, which conforms to the current green, low-carbon, and industrialized design concepts. In addition, its structural layout form is flexible and changeable. By changing parameters such as the section steel specification, the layout spacing in the height direction, and the transverse layout spacing of the longitudinal beams of the hot-rolled T-shaped steel 1, the structure can adapt to the bridge requirements of different spans and widths. At the same time, it has a high degree of prefabrication and fast construction, and has broad application prospects.

[0047] Second Embodiment:

[0048] In this embodiment, a construction method of a hot-rolled T-shaped steel 1 - UHPC assembled π-shaped composite beam is provided, which mainly includes the following steps:

[0049] S1, Select a hot-rolled T-shaped steel 1 that meets the design requirements according to the actual bridge span and width, and respectively open holes in the web and flange plate of the hot-rolled T-shaped steel 1 according to the design requirements; adjust the layout spacing of the symmetrically arranged hot-rolled T-shaped steel 1 in the height direction according to the actual beam height and perform temporary support and fixation;

[0050] S2, Bind the support steel bars 6 and U-shaped steel bars 5 inside the longitudinal beam; bind the transverse steel bars and vertical steel bars 10 inside the diaphragm 3; fabricate and install the side formwork of the longitudinal beam, the bottom formwork and side formwork of the diaphragm 3, and the formwork of the UHPC bridge deck 2; bind the longitudinal and transverse stress steel bars 4 inside the UHPC bridge deck 2;

[0051] S3. Pour the UHPC concrete 7 wrapped around both sides of the web of the hot-rolled T-shaped steel 1, the diaphragm 3, and the UHPC bridge deck 2, and after curing to the design strength, remove the formwork and the temporary fixing support members; the combined beam of a standard segment is formed by the longitudinal beam, the diaphragm 3, and the UHPC bridge deck 2, and during this process, reserve the position of the transverse wet joint 11 between segments according to the actual situation;

[0052] S4. Transport the prefabricated combined beam of the standard segment to the construction site, hoist the combined beam of the standard segment to the designated position for assembly construction; after all the combined beams in the transverse direction are installed in place, tie the longitudinal reinforcing bars at the reserved position of the transverse wet joint 11 and pour the UHPC concrete 7 to make all the combined beams of the standard segments form an integral whole.

[0053] In summary, in the construction method of the hot-rolled T-shaped steel 1-UHPC assembled π-shaped combined beam of the present application, by using rolled steel instead of welded steel plates and enabling the U-shaped steel bars 5 to extend into the UHPC bridge deck 2 through openings instead of shear studs, zero-weld construction is basically achieved, avoiding the influence of weld fatigue problems on the structural safety. At the same time, compared with conventional welding, the welding workload is reduced, energy consumption and carbon emissions are reduced, which conforms to the current green, low-carbon, and industrialized design concepts; moreover, its structural layout form is flexible and changeable. By changing parameters such as the section steel specification, the spacing in the height direction, and the transverse spacing of the longitudinal beams, it can meet the bridge requirements of different spans and widths. At the same time, it has a high degree of prefabrication and fast construction, and has broad application prospects.

[0054] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A hot-rolled T-shaped steel-UHPC assembled π-shaped composite beam, characterized in that, It includes two longitudinal beams, multiple transverse diaphragms and a UHPC bridge deck; the two longitudinal beams are vertically arranged in parallel at intervals, and each longitudinal beam is jointly composed of two hot-rolled T-shaped steels arranged symmetrically up and down and UHPC concrete wrapped around the outer periphery of the hot-rolled T-shaped steel; the multiple transverse diaphragms are vertically arranged in parallel at intervals, and both ends of each transverse diaphragm are respectively vertically connected between the side walls of the two longitudinal beams; the UHPC bridge deck is installed on the tops of the two longitudinal beams and the multiple transverse diaphragms, and multiple stress-bearing steel bars are evenly arranged at intervals in the longitudinal and transverse directions inside the UHPC bridge deck.

2. The hot-rolled T-shaped steel-UHPC assembled π-shaped composite beam according to claim 1, wherein The UHPC bridge deck is formed by jointly pouring UHPC concrete and multiple stress-bearing steel bars.

3. The hot-rolled T-shaped steel-UHPC assembled π-shaped composite beam according to claim 2, wherein Both ends of the multiple stress-bearing steel bars in the transverse direction inside the UHPC bridge deck extend out of both sides of the UHPC bridge deck.

4. The hot-rolled T-shaped steel-UHPC assembled π-shaped composite beam according to claim 1, characterized in that, Multiple support steel bars and multiple U-shaped steel bars are arranged inside each longitudinal beam; the support steel bars are sequentially arranged at intervals from bottom to top along the height direction of the longitudinal beam; the U-shaped steel bars are sequentially arranged at intervals along the length direction of the longitudinal beam, and the lower part of the U-shaped steel bar passes through the web of the hot-rolled T-shaped steel at the lower part of the longitudinal beam, and the upper part passes through the flange plate of the hot-rolled T-shaped steel at the upper part of the longitudinal beam and extends into the UHPC bridge deck.

5. The hot-rolled T-shaped steel-UHPC assembled π-shaped composite beam according to claim 4, wherein, Multiple first connection holes are opened at intervals along the length direction on the web of the hot-rolled T-shaped steel at the lower part of the longitudinal beam, and multiple second connection holes are opened at intervals along the length direction on the flange plate of the hot-rolled T-shaped steel at the upper part of the longitudinal beam, and both ends of the U-shaped steel bar are respectively connected to the first connection hole and the second connection hole.

6. The hot-rolled T-shaped steel-UHPC assembled π-shaped composite beam according to claim 5, wherein The total width of the UHPC concrete is equal to the width of the flange plate of the hot-rolled T-shaped steel.

7. The hot-rolled T-shaped steel-UHPC assembled π-shaped composite beam according to claim 1, wherein The layout spacing of the transverse diaphragms is 5 - 8m.

8. The hot-rolled T-shaped steel-UHPC assembled π-shaped composite beam according to claim 1, wherein, The transverse diaphragm is formed by jointly pouring multiple transverse steel bars, multiple vertical steel bars and UHPC concrete.

9. The hot-rolled T-shaped steel-UHPC assembled π-shaped composite beam according to claim 8, wherein, The multiple transverse steel bars are sequentially arranged in parallel at intervals along the height direction of the transverse diaphragm inside the transverse diaphragm, and both ends respectively extend into the two longitudinal beams on both sides; the multiple vertical steel bars are sequentially arranged in parallel at intervals along the length direction of the transverse diaphragm inside the transverse diaphragm, and the top ends extend into the UHPC bridge deck.

10. A construction method for a hot-rolled T-shaped steel-UHPC assembled π-shaped composite beam, characterized in that, It includes the following steps: S1, Select hot-rolled T-shaped steels that meet the design requirements according to the actual bridge span and width, and respectively drill holes in the webs and flange plates of the hot-rolled T-shaped steels according to the design requirements; Adjust the spacing of the symmetrically arranged hot-rolled T-shaped steels along the height direction according to the actual beam height and perform temporary support and fixation; S2, Bind the support steel bars and U-shaped steel bars inside the longitudinal beam; bind the transverse steel bars and vertical steel bars inside the transverse diaphragm; fabricate and install the side formwork of the longitudinal beam, the bottom formwork and side formwork of the transverse diaphragm, and the formwork of the UHPC bridge deck; bind the stress-bearing steel bars in the longitudinal and transverse directions inside the UHPC bridge deck; S3. Pour the UHPC concrete wrapped around the two sides of the web of the hot-rolled T-shaped steel, the diaphragm, and the UHPC bridge deck, and cure it to the design strength, then remove the formwork and the temporary fixed support members; the longitudinal beam, the diaphragm, and the UHPC bridge deck form a composite beam of a standard segment, and during this process, reserve the transverse wet joint position between segments according to the actual situation; S4. Transport the prefabricated composite beam of the standard segment to the construction site, hoist the composite beam of the standard segment to the designated position for assembly construction; after all the composite beams in the transverse direction are installed in place, tie the longitudinal reinforcement bars at the reserved transverse wet joint position and pour UHPC concrete to make all the composite beams of the standard segments form an integral whole.

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