An assembled steel-concrete pre-bent composite continuous beam bridge and its construction method

Abstract

The present invention relates to a prefabricated steel-concrete pre-bent composite continuous girder bridge and its construction method. At the pier top of the steel-concrete pre-bent composite continuous girder bridge, a steel-ultra-high performance concrete composite beam is adopted, and prestress is applied by means of pre-bent steel girders. In the mid-span, a steel-normal concrete composite beam is adopted, and the longitudinal joints of the pre-bent steel composite beam and the ordinary steel composite beam are placed in the middle of the bridge span. The present invention optimizes the bending moment distribution of the steel-concrete composite beam by means of continuous erection, achieves the purpose of reducing the beam height, and thus enlarges the applicable span of the steel-concrete composite beam bridge. Compared with the prior art, the present invention reduces the height-span ratio of the precast and assembled bridge on the premise of maximizing the assembly rate, reduces the engineering quantity of the substructure, and has great economic benefits.

Description

Technical Field

[0001] The present invention relates to the field of bridge engineering, and particularly to a prefabricated steel-concrete pre-bent composite continuous girder bridge. Background Art

[0002] Currently, prefabricated bridges mainly include hollow slabs, small box girders, T-girders, steel-concrete composite girders, etc. The commonly used methods of "simply supported first, then continuous" or "simply supported first, then continuous deck" are used to ensure the continuity of the bridge deck. This makes the mid-span bending moment control the design of the beam height. Therefore, the height-span ratio of the current prefabricated bridges is relatively large, resulting in certain material waste. Due to the current inherent specifications of steel sections, the height of the steel-concrete composite girder bridge is restricted, thereby limiting the applicable span range of the steel-concrete composite girder bridge. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problems existing in the above-mentioned prior art and provide a prefabricated steel-concrete pre-bent composite continuous girder bridge, which can reduce the height-span ratio of prefabricated bridges.

[0004] To achieve the above purpose, the technical solution of the present invention is as follows: A prefabricated steel-concrete pre-bent composite continuous girder bridge, characterized in that the girder bridge is spliced by several precast girders, and adjacent two precast girders are connected by longitudinal rigid joints, and the connection of the longitudinal rigid joints is located at 0.2-0.3L from the pier top at the mid-span, where L is the span between adjacent piers, and the precast girder at the pier top section is a precast steel-ultra-high performance concrete pre-bent composite beam.

[0005] Further, the girder bridge is composed of a first-span girder, several middle-span girders, and a last-span girder spliced together. The first-span girder includes a side-span section, a pier-top section, and a longitudinal rigid joint. The side-span section adopts a precast steel-ordinary concrete composite beam, and the pier-top section adopts a precast steel-ultra-high performance concrete pre-bent composite beam; the middle-span girder includes a mid-span section, a pier-top section, and longitudinal rigid joints at both ends of the middle-span girder. The mid-span section is a precast steel-ordinary concrete composite beam, and the pier-top section adopts a precast steel-ultra-high performance concrete pre-bent composite beam; the last-span girder includes a side-span section and a longitudinal rigid joint, and the side-span section adopts a precast steel-ordinary concrete composite beam; the deck slab of the precast steel-ultra-high performance concrete pre-bent composite beam adopts a prestressed ultra-high performance concrete deck slab; the deck slab of the precast steel-ordinary concrete composite beam adopts an ordinary concrete deck slab.

[0006] Further, the ordinary concrete here is in contrast to the ultra-high performance concrete, and generally refers to C40-C60 concrete.

[0007] Further, the side span section and pier top section of the first span beam and the mid-span section and pier top section of the mid-span beam are connected into one body by steel sections or connected by longitudinal rigid joints.

[0008] Further, the length of the ultra-high performance concrete bridge deck of the pier top section along the longitudinal direction is 0.1 - 0.15L on both sides of the pier top, where L is the span between adjacent piers. A pre-bent steel beam is used to apply prestress to the ultra-high performance concrete, and at the same time, the steel beam webs and bottom plates within the range of 0.1 - 0.15L on both sides of the pier top are wrapped with C40 - C60 concrete.

[0009] Further, the longitudinal rigid joint is connected by high-strength bolts.

[0010] Further, the steel beams of the side span section, pier top section and mid-span beam are made of rolled steel sections.

[0011] Another object of the present invention is to provide a construction method for an assembled steel-concrete pre-bent composite continuous beam bridge, which can reduce the height-span ratio of precast assembled bridges.

[0012] To achieve the above object, the technical solution of the present invention is as follows: A construction method for an assembled steel-concrete pre-bent composite continuous beam bridge, characterized in that the construction method includes the following steps:

[0013] A. Precast the first span beam, mid-span beam and end span beam. The first span beam includes a side span section, a pier top section and a longitudinal rigid joint. The side span section is a precast steel section-ordinary concrete composite beam, and the pier top section is a precast steel section-ultra-high performance concrete pre-bent composite beam; the mid-span beam includes a mid-span section, a pier top section and a longitudinal rigid joint. The mid-span section is a precast steel section-ordinary concrete composite beam, and the pier top section is a precast steel section-ultra-high performance concrete pre-bent composite beam; the end span beam includes a side span section and a longitudinal rigid joint, and the side span section is a precast steel section-ordinary concrete composite beam; the bridge deck of the precast steel section-ultra-high performance concrete pre-bent composite beam uses a prestressed ultra-high performance concrete bridge deck; the bridge deck of the precast steel section-ordinary concrete composite beam uses an ordinary concrete bridge deck;

[0014] B. Erect the first span beam and make the pier top section of the first span beam located at the pier top position;

[0015] C. Erect the remaining mid-span beams of each span one by one and make the pier top sections of the mid-span beams located at the pier top positions. After the erection of the next span is completed, it is bolt-connected to the steel beam of the previous span. Erection is carried out step by step until the end. In the last span, the end span beam is used to connect with the previously erected beam segments;

[0016] D. The concrete bridge deck of the on-site joint section is laid with precast slabs;

[0017] E. Horizontally connect each pre-bent composite beam to form a pre-bent composite beam bridge;

[0018] F. Complete the construction of ancillary facilities such as paving and railings.

[0019] Specifically, according to one embodiment of the present invention, prefabricating the mid-span beam in step A may include the following steps:

[0020] Step 1: Form an H-shaped steel beam with a length of L, and a pre-camber is set within 0.5L at one end of the H-shaped steel;

[0021] Step 2: Temporarily connect the two H-shaped steel beams with a length of L and the pre-arched beam ends with bolts to form a steel beam with a length of 2L. Set fulcrums at 0.45L on both sides of the connection node, set reaction frames at both ends of the 2L steel beam, and place jacks between the reaction frames and the steel beam;

[0022] Step 3: Lift the jack to pre-bend the 2L long H-shaped steel beam formed by the connection, pour ultra-high performance concrete within the range of 0.1L~0.4L from the connection node to form the bridge deck and use steam curing. After the strength reaches the standard, release the steel beam and release the temporary connection;

[0023] Step 4: Except for the longitudinal range of 0.1L at both ends of the steel beam, the upper edge of the rest of the steel beam is poured with C50 concrete and cured to form an ordinary concrete bridge deck. The web and bottom plate of the steel beam under the ultra-high performance concrete bridge deck are wrapped with C50 concrete and cured to finally form a mid-span beam with a length of L.

[0024] Specifically, according to another embodiment of the present invention, prefabricating the mid-span beam in step A may include the following steps:

[0025] Step 1: forming an H-shaped steel beam with a length of 0.5L, and some 0.5L steel beams are provided with pre-camber;

[0026] Step 2: Pre-bend the steel beam with a length of 0.5L and cast the top plate with ultra-high performance concrete with a longitudinal length of about 0.3L to form the bridge deck and steam cure it. After the strength reaches the standard, release the steel beam to form the pier top section;

[0027] Step 3: Connect the 0.5L long steel beam without pre-arch to the prefabricated pier top section with bolts.

[0028] Step 4: Except for the longitudinal range of 0.1L at both ends of the steel beam, the upper edge of the rest of the steel beam is poured with C50 concrete and cured to form a bridge deck. The web and bottom plate of the steel beam under the ultra-high performance concrete bridge deck are wrapped with C50 concrete and cured to finally form a mid-span beam with a length of L.

[0029] The feature of the present invention is that the longitudinal joint positions of each precast beam are set at a distance of 0.25L from the center line of the pier at the mid-span, that is, after each hoisted precast beam segment is connected with 0.25L of the previous span beam segment to form a bridge, 0.25L of its length crosses the pier and enters the next span, and so on. The present invention optimizes the bending moment distribution of the steel-concrete composite beam by means of continuous erection, achieving the purpose of reducing the beam height, thereby expanding the applicable span of the steel-concrete composite beam bridge. The steel beam at the pier top section is wrapped with concrete, increasing the pier top stiffness and further optimizing the bending moment distribution. The added concrete also enhances the shear and bending bearing capacities at the pier top, thereby further increasing the applicable span of the steel section; the bridge deck at the pier top section adopts ultra-high performance concrete and applies prestress by means of pre-bending technology to reduce the cracks in the negative bending moment area, not only enhancing the structural durability but also ensuring that the stiffness of the pier top does not decrease. Compared with the prior art, the present invention reduces the height-span ratio of the precast assembled bridge on the premise of maximizing the assembly rate, reduces the engineering quantity of the substructure, and has great economic benefits. Description of the Drawings

[0030] Figure 1 It is a front elevation view of the "mid-span beam" of the precast assembled steel-concrete pre-bent composite continuous beam bridge in Embodiment 1 of the present invention;

[0031] Figure 2 It is a cross-sectional view of the "first span beam" of the precast assembled steel-concrete pre-bent composite continuous beam bridge in Embodiment 1 of the present invention;

[0032] Figure 3 It is a schematic view of the "end span beam" of the precast assembled steel-concrete pre-bent composite continuous beam bridge in Embodiment 1 of the present invention;

[0033] Figure 4 It is a cross-sectional view of the "pier top section" of the precast assembled steel-concrete pre-bent composite continuous beam bridge in Embodiment 1 of the present invention;

[0034] Figure 5 It is a schematic view of the "mid-span section" of the precast assembled steel-concrete pre-bent composite continuous beam bridge in Embodiment 1 of the present invention;

[0035] Figure 6 It is a schematic view of the manufacturing method of the "mid-span beam" of the precast assembled steel-concrete pre-bent composite continuous beam bridge in Embodiment 1 of the present invention;

[0036] Figure 7 It is a schematic view of the pre-bending process of the "mid-span beam" of the precast assembled steel-concrete pre-bent composite continuous beam bridge in Embodiment 1 of the present invention;

[0037] Figure 8 It is a schematic view of the on-site erection steps in the longitudinal bridge direction of the precast assembled steel-concrete pre-bent composite continuous beam bridge in Embodiment 1 of the present invention.

[0038] Figure 9 It is a front elevation view of the "mid-span beam" of the prefabricated steel-concrete pre-bent composite continuous girder bridge in Embodiment 2 of the present invention;

[0039] Figure 10 It is a cross-sectional view of the "first-span beam" of the prefabricated steel-concrete pre-bent composite continuous girder bridge in Embodiment 2 of the present invention;

[0040] Figure 11 It is a view of the "end-span beam" of the prefabricated steel-concrete pre-bent composite continuous girder bridge in Embodiment 2 of the present invention;

[0041] Figure 12 It is a cross-sectional view of the "pier top section" of the prefabricated steel-concrete pre-bent composite continuous girder bridge in Embodiment 2 of the present invention;

[0042] Figure 13 It is a view of the "mid-span section" of the prefabricated steel-concrete pre-bent composite continuous girder bridge in Embodiment 2 of the present invention;

[0043] Figure 14 It is a schematic diagram of the manufacturing method of the "mid-span beam" of the prefabricated steel-concrete pre-bent composite continuous girder bridge in Embodiment 2 of the present invention;

[0044] Figure 15 It is a schematic diagram of the on-site erection steps of the prefabricated steel-concrete pre-bent composite continuous girder bridge in the longitudinal direction of the bridge in Embodiment 2 of the present invention.

[0045] In the figure, 1 - ultra-high performance concrete bridge deck of the pier top section, 2 - H-shaped steel girder, 3 - C50 concrete bridge deck, 4 - pier top section, 5 - mid-span section, 6 - side-span section, 61 - precast concrete slab or cast-in-place joint on-site, 7 - bridge pier, 21 - concrete wrapping of the pier top section, 8 - jack lifting force, 9 - reaction frame, 10 - support pier, 11 - pre-arch steel girder, 12 - 0.5L steel girder, 13 - 0.75L steel girder. Detailed implementation manners

[0046] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Embodiment 1

[0048] A new type of prefabricated steel-concrete pre-bent composite continuous beam bridge, taking a 4*40m continuous beam bridge as an example. Its main beam includes "pier top section", "mid-span section", "side span section" and rigid joints. It is characterized in that the top plate of the "pier top section" is made of ultra-high performance concrete and prestressed. The concrete bridge deck of the "mid-span section" is made of ordinary C50 concrete. The joint is at the bridge span 0.25L=10m, and the concrete bridge deck on the rigid joint is a precast plate. The steel beams of the "pier top section", "mid-span section" and "side span section" are made of rolled steel.

[0049] Furthermore, the longitudinal length of the ultra-high performance concrete bridge deck of the "pier top section" is 0.15L=6m on both sides of the pier top (L is the span between adjacent piers), and pre-bent steel beams are used to apply prestress to the ultra-high performance concrete.

[0050] The first is the factory prefabrication process, which is divided into the following four steps:

[0051] Step 1: Form H-shaped steel beams with lengths of L=40m (L is the span between adjacent piers), 0.75L=30m and 1.25L=50m, with a pre-camber within 0.5L=20m at one end of the H-shaped steel.

[0052] Step 2: Temporarily connect the two H-shaped steel beams with a length of L and the pre-arched beam ends with bolts to form a steel beam with a length of 2L=80m. Set fulcrums at 0.45L=18m on both sides of the connection node, set reaction frames at both ends of the 2L steel beam, and place jacks between the reaction frames and the steel beam.

[0053] Step 3: Lift the jack to pre-bend the 2L long H-shaped steel beam formed by the connection, pour ultra-high performance concrete within the range of 0.lL~0.4L (4~16m) from the connection node to form the bridge deck and use steam curing. After the strength reaches the standard, release the steel beam and release the temporary connection.

[0054] Step 4: Except for the longitudinal range of 0.1L=4m at both ends of the steel beam, the upper edge of the rest of the steel beam is poured with C50 concrete and cured to form an ordinary concrete bridge deck. The web and bottom plate of the steel beam under the ultra-high performance concrete bridge deck are wrapped with C50 concrete and cured, and finally a "mid-span beam" steel composite beam with a length of L=40m is formed. The prefabrication method of the "first span beam" steel composite beam with a length of 1.25L=50m is similar to that of the "mid-span beam", and the prefabrication method of the "tail span beam" with a length of 0.75L=30m is similar to that of the ordinary steel-concrete composite beam.

[0055] After the prefabricated prestressed beam is completed, it can be transported to the site for erection. The erection is mainly divided into the following steps:

[0056] The first step: Erect the "first-span beam".

[0057] The second step: Erect the "mid-span beams" of the remaining spans one by one. After the erection of the next span is completed, bolt connections are used with the steel beams of the previous span. Erection is carried out step by step until the end. For the last span, use the "tail-span beam" to connect with the previously erected beam segments.

[0058] The third step: The concrete bridge deck of the on-site joint section is paved with precast slabs.

[0059] The fourth step: Horizontally connect the pre-bent composite beams to form a pre-bent composite beam bridge.

[0060] The fifth step: Complete the construction of ancillary facilities such as paving and railings.

[0061] Embodiment 2

[0062] A new type of assembled steel-concrete pre-bent composite continuous beam bridge, taking a 4*40m continuous beam bridge as an example. Its main girders include "pier top section", "mid-span section", "side-span section" and rigid joints. It is characterized in that the top slab of the "pier top section" adopts ultra-high performance concrete and prestress is applied. The concrete bridge deck of the "mid-span section" adopts ordinary C50 concrete. The joint is at 0.25L = 10m of the bridge span, and the concrete bridge deck on the rigid joint adopts precast slabs. The steel beams of the "pier top section", "mid-span section" and "side-span section" adopt rolled steel sections.

[0063] Furthermore, the longitudinally extending length of the ultra-high performance concrete bridge deck of the "pier top section" is 0.15L = 6m on both sides of the pier top (L is the span between adjacent piers), and pre-bent steel beams are used to apply prestress to the ultra-high performance concrete.

[0064] First is the factory prefabrication link, which is divided into the following four steps:

[0065] The first step: Form H-shaped steel beams with lengths of 0.5L = 20m (L is the span between adjacent piers) and 0.75L = 30m. Some of the 0.5L = 20m steel sections need to be provided with cambers.

[0066] The second step: Pre-bend the 0.5L = 20m steel beam with camber. The pre-bending method adopts the single-beam pre-bending or double-beam opposite-bending pre-bending methods provided in the "Technical Standard for Pre-bent Prestressed Composite Beam Bridges" CJJ / T 276-2018. Pour ultra-high performance concrete with a longitudinally extending length of about 0.3L = 12m on the top slab to form the bridge deck and adopt steam curing. After the strength meets the standard, release the tension of the steel beam to form the "pier top section".

[0067] The third step: Connect the 0.5L = 20m steel beam without camber to the prefabricated "pier top section" with bolts.

[0068] Step 4: For the connected steel girders, except for not pouring within the range of 0.1L = 4m along the longitudinal direction at both ends, C50 concrete is poured and cured at the upper edge of the steel girder where ultra-high performance concrete is not provided to form a bridge deck. The web and bottom plate of the steel girder below the ultra-high performance concrete bridge deck are wrapped with C50 concrete and cured, finally forming a "mid-span girder" with a length of L.

[0069] For the "first-span girder", in Step 3, the steel girder with a length of 0.75L = 30m without a pre-arch is connected to the precast "pier-top section" with bolts. In Step 4, for the connected steel girder, except for not pouring within the range of 0.1L = 4m along the longitudinal direction at the end of the steel girder near the pier-top section, C50 concrete is poured and cured at the upper edge of the steel girder where ultra-high performance concrete is not provided to form a bridge deck. The web and bottom plate of the steel girder below the ultra-high performance concrete bridge deck are wrapped with C50 concrete and cured, finally forming a "first-span girder" with a length of 1.25L = 50m.

[0070] The prefabrication method of the "last-span girder" with a length of 0.75L = 30m is similar to that of a common steel-concrete composite girder.

[0071] After the prefabricated prestressed beam is completed, it can be transported to the site for erection. The erection is mainly divided into the following steps:

[0072] Step 1: Erect the "first-span girder";

[0073] Step 2: Erect the "mid-span girders" of the remaining spans one by one, and after the erection of the next span is completed, connect the steel girders of the previous span with bolts. Erection is carried out according to this step until the end, and in the last span, the "last-span girder" is used to connect with the previously erected girder segments.

[0074] Step 3: The concrete bridge deck of the on-site joint section is paved with precast slabs.

[0075] Step 4: Horizontally connect the pre-bent composite girders to form a pre-bent composite girder bridge.

[0076] Step 5: Complete the construction of ancillary facilities such as paving and railings.

[0077] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to the embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A construction method for an assembled steel-concrete pre-bent composite continuous beam bridge, characterized in that The construction method comprises the following steps: A, prefabricating a first span beam, a middle span beam and a tail span beam, wherein the first span beam comprises a side span section, a pier top section and a longitudinal rigid joint, wherein the side span section adopts a prefabricated steel-ordinary concrete composite beam, and the pier top section adopts a prefabricated steel-ultra-high performance concrete pre-bent composite beam; the middle span beam comprises a mid-span section, a pier top section and a longitudinal rigid joint, wherein the mid-span section is a prefabricated steel-ordinary concrete composite beam, and the pier top section adopts a prefabricated steel-ultra-high performance concrete pre-bent composite beam; the tail span beam comprises a side span section and a longitudinal rigid joint, and the side span section adopts a prefabricated steel-ordinary concrete composite beam; the bridge deck of the prefabricated steel-ultra-high performance concrete pre-bent composite beam adopts a prestressed ultra-high performance concrete bridge deck; the bridge deck of the prefabricated steel-ordinary concrete composite beam adopts an ordinary concrete bridge deck; B. Erect the first span beam and make the pier top section of the first span beam located at the pier top position; C. Erect the middle span beams of the remaining spans one by one, and make the pier top section of the middle span beam be located at the pier top position. After the next span is erected, it is connected to the steel beam of the previous span with bolts. Erect in this way until the end, and use the tail span beam of the last span to connect it with the previously erected beam section; D. The concrete bridge deck of the on-site joint section is laid with precast slabs; E. Transversely connect the pre-bent composite beams to form a pre-bent composite beam bridge; F. Complete the construction of paving and railing ancillary facilities; The prefabrication of the mid-span beam in step A includes the following steps: Step 1: Form an H-shaped steel beam with a length of L, and a pre-camber is set within 0.5L at one end of the H-shaped steel; Step 2: Temporarily connect the two H-shaped steel beams with a length of L and the pre-arched beam ends with bolts to form a steel beam with a length of 2L. Set fulcrums at 0.45L on both sides of the connection node, set reaction frames at both ends of the 2L steel beam, and place jacks between the reaction frames and the steel beam; Step 3: Lift the jack to pre-bend the 2L long H-shaped steel beam formed by the connection, pour ultra-high performance concrete within the range of 0.1L~0.4L from the connection node to form the bridge deck and use steam curing. After the strength reaches the standard, release the steel beam and release the temporary connection; Step 4: Except for the longitudinal range of 0.1L at both ends of the steel beam, the upper edge of the rest of the steel beam is poured with C50 concrete and cured to form an ordinary concrete bridge deck. The web and bottom plate of the steel beam under the ultra-high performance concrete bridge deck are wrapped with C50 concrete and cured to finally form a mid-span beam with a length of L.

2. A construction method for an assembled steel-concrete pre-bent composite continuous beam bridge, characterized in that, The construction method includes the following steps: A. Prefabricate the first-span beam, middle-span beam and last-span beam. The first-span beam includes a side-span section, a pier-top section and a longitudinal rigid connection joint. The side-span section adopts a prefabricated steel section-ordinary concrete composite beam, and the pier-top section adopts a prefabricated steel section-ultra-high performance concrete pre-bent composite beam; the middle-span beam includes a mid-span section, a pier-top section and a longitudinal rigid connection joint. The mid-span section is a prefabricated steel section-ordinary concrete composite beam, and the pier-top section adopts a prefabricated steel section-ultra-high performance concrete pre-bent composite beam; the last-span beam includes a side-span section and a longitudinal rigid connection joint, and the side-span section adopts a prefabricated steel section-ordinary concrete composite beam; the deck slab of the prefabricated steel section-ultra-high performance concrete pre-bent composite beam adopts a prestressed ultra-high performance concrete deck slab; the deck slab of the prefabricated steel section-ordinary concrete composite beam adopts an ordinary concrete deck slab. B. Erection the first-span beam and make the pier-top section of the first-span beam located at the pier-top position. C. Erection the remaining middle-span beams span by span and make the pier-top sections of the middle-span beams located at the pier-top positions. After the erection of the next span is completed, it is bolted to the steel beam of the previous span. Erection is carried out step by step until the end, and the last-span beam is used to connect with the previously erected beam segments in the last span. D. The concrete deck slab of the on-site joint section is laid with prefabricated slabs. E. Horizontally connect each pre-bent composite beam to form a pre-bent composite beam bridge. F. Complete the construction of the paving, railing and other ancillary facilities. Among them, the prefabrication of the middle-span beam in step A includes the following steps: The first step: Form an H-shaped steel beam with a length of 0.5L, and some of the steel sections with a length of 0.5L are provided with cambers. The second step: Pre-bend the steel beam with a length of 0.5L with cambers, pour ultra-high performance concrete with a longitudinal length of about 0.3L on the top plate to form a deck slab and adopt steam curing. After the strength reaches the standard, release the tension of the steel beam to form the pier-top section. The third step: Connect the steel beam with a length of 0.5L without cambers to the prefabricated pier-top section with bolts. The fourth step: Except for not pouring within the range of 0.1L along the longitudinal direction at both ends of the steel beam, C50 concrete is poured and cured on the upper edge of the rest of the steel beam to form a deck slab, and the web and bottom plate of the steel beam under the ultra-high performance concrete deck slab are wrapped with C50 concrete and cured, and finally a middle-span beam with a length of L is formed.

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