CN115679794B - Large cantilever ultra-wide UHPC box girder unit, large cantilever ultra-wide UHPC box girder bridge and its construction method - Google Patents

Abstract

The invention discloses a large cantilever ultra-wide UHPC box girder unit, which comprises a UHPC box girder body, and UHPC flanges extending outward are arranged on both sides of the cross bridge on the upper surface of the UHPC box girder body, and the UHPC box girder body Between the side of the UHPC flange and the bottom surface of the UHPC flange, there are multiple UHPC cantilever beams arranged at intervals, and there are multiple UHPC longitudinal ribs arranged at intervals under the UHPC flange, and the UHPC cantilever beams are arranged along the transverse bridge direction , the UHPC longitudinal ribs are arranged along the longitudinal bridge direction. The invention also provides a large cantilever ultra-wide UHPC box girder bridge and a construction method. The box girder bridge obtained by the construction of the large cantilever ultra-wide UHPC box girder unit of the present invention can greatly increase the width of the bridge deck and improve the stiffness of the box girder flange plate when the lateral distance of the support is limited, which can effectively avoid cracking of the bridge deck and is convenient Assembled construction.

Description

Large cantilever ultra-wide UHPC box girder unit, large cantilever ultra-wide UHPC box girder bridge and its construction method

technical field

The invention belongs to the field of bridges, in particular to a UHPC box girder unit, a UHPC box girder bridge and a construction method thereof.

Background technique

With the construction of the Hong Kong-Zhuhai-Macao Bridge and the development of urban traffic, more and more bridges will be built on the sea and in the city. With the increase in traffic volume and the improvement of road grades, some new bridges require the construction of two-way six-lane or even Two-way eight-lane, so that the width of the bridge reaches 35m or wider. However, for traditional wide box girder bridges, due to the substantial increase in bridge width, the position of pier is limited by objective conditions (short urban land use or harsh geological conditions at sea, etc.), and the transverse spacing of bridge supports is small, which makes the box girder flange plate challenge The arm is longer, which leads to significant lateral effect of the box girder structure of the bridge during service, obvious transverse shear deformation and large vertical deformation at the end of the box girder transverse cantilever, insufficient local stiffness, and prone to cracking of the bridge deck Phenomenon.

In order to solve the above technical problems, steel box girder structures and composite box girder structures (steel-concrete composite beams) are used in the prior art. However, due to the use of steel in such bridge structures, not only the initial construction costs and construction procedures (welding There are many seam details), and due to steel fatigue and corrosion problems, the operation and maintenance costs will be greatly increased. In addition, the general steel box girder structure contains a thick and heavy ordinary concrete layer. On the one hand, it increases the structure's own weight and construction procedures, which is not conducive to assembly construction; Bridge deck concrete will inevitably crack. Therefore, the prior art cannot perfectly solve the cracking problem of the super-wide box girder bridge deck.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology, to provide a large cantilever ultra-wide UHPC box girder unit, a large cantilever ultra-wide UHPC box girder bridge and its construction method, through which the large cantilever ultra-wide The box girder bridge obtained by the construction of wide UHPC box girder units can greatly increase the width of the bridge deck and increase the stiffness of the box girder flange plate when the lateral distance of the supports is limited, which can effectively avoid cracking of the bridge deck and facilitate assembly construction. In order to solve the problems of the technologies described above, the technical solution proposed by the present invention is:

A large cantilever ultra-wide UHPC box girder unit, including a UHPC box girder body, UHPC flanges extending outward are provided on both sides of the cross bridge on the upper surface of the UHPC box girder body, the sides of the UHPC box girder body and the Between the bottom surface of the UHPC flange, there are multiple UHPC beams arranged at intervals, and under the UHPC flange, there are multiple UHPC longitudinal ribs arranged at intervals. The UHPC beams are arranged along the transverse bridge direction, and the UHPC The longitudinal ribs are arranged along the longitudinal bridge direction.

In the above-mentioned large cantilever ultra-wide UHPC box girder unit, preferably, the UHPC box girder body includes a UHPC top plate, a UHPC bottom plate, a UHPC transverse diaphragm and a UHPC web arranged along the longitudinal bridge direction, and the UHPC web is arranged on the A box structure is formed between the UHPC top plate and the UHPC bottom plate, the UHPC transverse diaphragm includes at least one of the UHPC top plate stiffener, the UHPC web stiffener, and the UHPC bottom plate stiffener, and the UHPC top plate stiffener is vertically arranged At the bottom of the UHPC top plate, the UHPC web stiffener is vertically arranged on the side wall of the UHPC web, and the UHPC bottom plate stiffener is vertically arranged on the upper part of the UHPC bottom plate.

In the above-mentioned large cantilever ultra-wide UHPC box girder unit, preferably, the UHPC web includes a UHPC inner web and a UHPC outer web, and the UHPC outer web is arranged on both sides of the transverse bridge of the box structure, The UHPC inner web is arranged at the center of the longitudinal bridge of the box structure, the thickness of the UHPC inner web and the UHPC outer web are both 0.15-0.50m, and the thickness of the UHPC bottom plate is 0.15-1.20m m, the thickness of the UHPC diaphragm is 0.15-0.40m, the UHPC diaphragm is arranged every 2-6m along the longitudinal bridge, and the height of the UHPC diaphragm is 0.50-1.50m. The settings of the above process parameters are all based on the span and width of the engineering background bridge, which can save materials, make full use of the high-strength characteristics of UHPC, enhance local stiffness, and reduce bridge construction costs.

The large cantilever and ultra-wide UHPC box girder unit of the present invention can be a single-box multi-chamber structure. When a single-box multi-chamber structure is adopted, the UHPC webs include UHPC outer webs on both sides and UHPC inner webs inside the box structure Due to the existence of the UHPC inner web, the torsional stiffness of the box girder will be greatly improved. At this time, some UHPC diaphragms only need to strengthen the top and bottom plates.

In the above-mentioned large cantilever ultra-wide UHPC box girder unit, preferably, the UHPC flange is integrally formed with the UHPC box girder body, and the UHPC cantilever is pre-embedded with a tensile member extending into the UHPC box girder body. Reinforcing bars, the UHPC diaphragm includes UHPC roof stiffeners with a height no less than that of the UHPC cantilever, one end of the tensile steel bar is buried in the UHPC cantilever, and the other end passes through the UHPC web and extends into the UHPC roof stiffener.

In the above-mentioned large cantilever ultra-wide UHPC box girder unit, preferably, the same UHPC cantilever is pre-embedded with a plurality of tensile reinforcements arranged at equal intervals along different heights, and the tensile reinforcements include the first main reinforcement and the The first end hooks at both ends of the first main reinforcement are arranged symmetrically along the midpoint of the first main reinforcement, and the first main reinforcements adjacent to the tensile reinforcement are dislocated up and down. The above-mentioned dislocation setting means that the upper and lower adjacent first main reinforcements are located at different longitudinal and bridging positions, and more preferably, the longitudinal and bridging positions of the spaced apart first main reinforcements remain the same.

Since most UHPC box girders are thin-walled structures, the use of transverse prestressing is not only complicated in process, but also lacks proper placement. The large cantilever and ultra-wide UHPC box girder unit of the present invention does not need to be equipped with transverse prestressed beams, but only needs to be equipped with tensile steel bars , strengthen the connection between the UHPC flange and the UHPC diaphragm and increase the lateral stiffness of the ultra-wide box girder unit, which is sufficient to resist the cantilever effect of the flange plate. The tensile steel bar of the present invention adopts the dislocation steel bar structure distributed equidistantly, and its end is strengthened by means of the first end hook (such as a 180° hook), and the first main bar with the first end hook does not need to be very complicated. Processing mode, simple structure, the use of hooks at the end can greatly improve the pull-out resistance of the end, the anchoring force of the end is strong, and the dislocation arrangement can make more effective use of the contact surface between the steel bar and the UHPC matrix, improving the bonding force and stress It is more uniform and is especially suitable for the box girder structure of the prefabricated construction of the present invention. The UHPC cantilever beam of the present invention is strengthened by the integrity of the first main reinforcement with the first end hook arranged in a dislocation and the UHPC diaphragm, and the main load transfer path of the UHPC flange is: flange → cantilever beam → steel bar → diaphragm →The main body of the box girder, the way of force transmission is stable and reliable, and the force is simple, which can effectively prevent the bridge deck from cracking.

In the above-mentioned large cantilever ultra-wide UHPC box girder unit, preferably, the UHPC flange, the UHPC cantilever and the UHPC box girder body are connected by a cast-in-situ UHPC wet joint, and the UHPC box girder body The upper part of the cross bridge is provided with an upper bevel corresponding to the position of the UHPC flange and a lower groove corresponding to the position of the UHPC cantilever. The upper bevel and the lower groove are cast-in-place UHPC Form cast-in-place UHPC wet joints.

In the above-mentioned large cantilever ultra-wide UHPC box girder unit, preferably, the UHPC box girder body is pre-embedded with a second reserved steel bar at the upper slant and the lower groove, and the second reserved steel bar at the upper slant A plurality of steel bars are evenly arranged, one end is set in the UHPC roof, and the other end extends to the cast-in-place UHPC wet joint, and the UHPC diaphragm includes a UHPC roof stiffener whose height is not less than the UHPC cantilever Ribs, the second reserved steel bars at the lower groove are arranged at equal intervals along different heights, one end is arranged in the stiffener of the UHPC top plate, and the other end extends toward the cast-in-place UHPC wet joint; The UHPC flange is provided with a third reserved reinforcement at a position corresponding to the second reserved reinforcement at the upper bevel, and one end of the third reserved reinforcement in the UHPC flange is arranged in the UHPC flange, The other end extends into the cast-in-place UHPC wet joint, and the UHPC cantilever is also provided with a third reserved reinforcement at a position corresponding to the second reserved reinforcement at the lower groove, and the UHPC cantilever One end of the third reserved steel bar is arranged in the UHPC cantilever, and the other end extends to the cast-in-situ UHPC wet joint.

In the above-mentioned large cantilever ultra-wide UHPC box girder unit, preferably, the second reserved reinforcement includes a second main reinforcement, and the second main reinforcement is provided with a second end hook near the end of the cast-in-place UHPC wet joint, so The third reserved reinforcement includes a third main reinforcement, and the end of the third main reinforcement close to the cast-in-place UHPC wet joint is provided with a third end hook, and the horizontal bridge is dislocated up and down adjacent to the second main reinforcement and the third main reinforcement Arranged, and both the second end hook and the third end hook cross the center line of the longitudinal bridge of the cast-in-place UHPC wet joint.

In the above-mentioned large cantilever ultra-wide UHPC box girder unit, preferably, prestressed tendons arranged along the length of the transverse bridge are also arranged between the UHPC cantilever beam and the UHPC box girder body, and the UHPC transverse diaphragm includes UHPC roof stiffeners with a height not less than the UHPC cantilever, the two ends of the prestressed tendons are respectively anchored to the ends of the UHPC cantilever (located in the UHPC cantilever on the lateral side of the cross bridge, and located in the UHPC cantilever The transverse bridge of the cantilever beam faces to the outermost end), and the middle part of the prestressed tendon passes through the stiffener of the UHPC top plate.

Since most UHPC box girders are of thin-walled structure, the use of transverse prestressing is not only complicated in process, but also lacks proper placement. The large cantilever and ultra-wide UHPC box girder unit of the present invention, through simply arranging prestressed tendons and UHPC wet joints, through Set the second reserved reinforcement and the third reserved reinforcement of specific forms at the UHPC wet joints to strengthen the connection between the UHPC flange and the UHPC diaphragm and increase the lateral stiffness of the ultra-wide box girder unit, which is sufficient to resist the flange The cantilever effect of the plate. The reserved steel bar of the present invention adopts the upper and lower misplaced steel bar structure, and its end is reinforced by end hooks (such as 180° hooks). The hook form can greatly improve the pull-out resistance of the end, and the anchoring force of the end is stronger. The dislocation arrangement can make more effective use of the contact surface between the steel bar and the UHPC matrix, improve the bonding force, and the force is more uniform, and the force transmission path is stable and reliable. The force is simple and can effectively avoid cracking of the bridge deck, and is especially suitable for the box girder structure of the prefabricated construction of the present invention.

In the above-mentioned large cantilever ultra-wide UHPC box girder unit, preferably, the UHPC box girder body has a transverse width of 15-40m, the UHPC flange has a transverse width of 5-10m, and the UHPC flange It is arranged symmetrically toward the center along the longitudinal bridge of the UHPC box girder body. The transverse width of the UHPC box girder body of the present invention is 15-40m, the transverse width of the UHPC flange is 5-10m, the width of the whole box girder can reach 20-50m, and the bridge width is wider.

In the above-mentioned large cantilever ultra-wide UHPC box girder unit, preferably, the UHPC cantilever is arranged symmetrically to the center along the longitudinal bridge, the thickness of the UHPC cantilever is 0.1-0.8m, and the transverse width of the UHPC cantilever is The height of the UHPC cantilever is 5-10m, the closer the height of the UHPC cantilever is to the body of the UHPC box girder, the higher the height of the higher side is 2-5m, and the height of the lower side is 0.1-0.6m. The longitudinal span between the centers of the UHPC cantilever beams is 2-6m.

In the above-mentioned large cantilever ultra-wide UHPC box girder unit, preferably, the UHPC longitudinal rib is an inverted trapezoid with a wide top and a narrow bottom, the height of the UHPC longitudinal rib is 0.2-0.8m, and the upper edge width of the UHPC longitudinal rib 0.3-0.8m, the width of the lower edge is 0.2-0.6m, and the transverse distance between the centers of the adjacent UHPC longitudinal ribs is 0.3-1.5m.

The above process parameter setting of the UHPC cantilever and UHPC longitudinal rib of the present invention is beneficial for both of them to cooperate with the UHPC box girder body to greatly increase the width of the bridge deck and increase the stiffness of the box girder flange plate to effectively avoid cracking of the bridge deck.

As a general technical concept, the present invention also provides a large cantilever ultra-wide UHPC box girder bridge, including bridge piers and a plurality of the above-mentioned large cantilever ultra-wide UHPC box girder units, and a plurality of the large cantilever ultra-wide UHPC box girder units The prestressed system is assembled along the longitudinal bridge direction to form a whole.

In the above-mentioned large cantilever ultra-wide UHPC box girder bridge, preferably, the prestressing system includes internal prestressing beams and external prestressing beams, and the internal prestressing beams are embedded in the UHPC longitudinal ribs along the longitudinal bridge direction, The external prestressing beam is arranged through the UHPC diaphragm along the longitudinal bridge direction, the external prestressing beam is anchored by an external beam tooth block, and is turned by an integrated external beam steering block, and the external beam tooth block and The extracorporeal beam steering blocks are all embedded and fixed on the UHPC transverse diaphragm and consolidated with the inner side wall of the UHPC web. The internal prestressed beams are embedded in the UHPC longitudinal ribs, which can greatly increase the local bending capacity of the UHPC flange, increase the stiffness of the UHPC flange to a certain extent, reduce the deformation of the box girder, and avoid cracking of the bridge deck.

As a general technical concept, the present invention also provides a construction method for the above-mentioned large cantilever ultra-wide UHPC box girder bridge, including the following steps:

S1: Construction pile foundation and bridge piers;

S2: Install the 0# large cantilever ultra-wide UHPC box girder unit segment on the pier, and assemble other large Cantilever ultra-wide UHPC box girder unit segments, and complete the tensioning of the corresponding prestressed system;

S3: The side spans are closed first, and then the temporary consolidation of the 0# large cantilever ultra-wide UHPC box girder unit section is removed, and finally the middle span is closed, and the prestressed system is tensioned within the entire span of the bridge;

S4: Complete the ancillary works of the large cantilever ultra-wide UHPC box girder bridge and the bridge deck pavement, that is, the construction is completed.

The use of steel box girder or composite box girder structure (steel-concrete composite beam) in the prior art cannot solve the problem of bridge deck cracking well, and will also bring problems in construction and other aspects. Ultra-high performance concrete (UHPC) has excellent mechanical properties and super durability. Existing engineering practices have shown that UHPC applied to bridge engineering can greatly reduce the structure size and improve the local stiffness of the bridge, and is conducive to assembly construction. Therefore, the ultra-wide box girder bridge based on the UHPC material of the present invention is expected to solve the technical problems existing in the traditional ultra-wide girder bridge.

The UHPC adopted in the present invention has high strength and high toughness performance and can avoid partial cracking of the bridge deck. In addition, in the direction of the longitudinal bridge, the bottom surface of the UHPC flange is stiffened with UHPC longitudinal ribs and prestressed beams embedded in the longitudinal ribs, which greatly improves the bending strength; The connection between the UHPC cantilever beam and the UHPC diaphragm is strengthened by the tensile reinforcement arranged in a dislocation to enhance the overall stability; or in the direction of the transverse bridge, the UHPC flange and UHPC The beam and the UHPC box girder body are connected as a whole, and then the connection between the UHPC cantilever beam and the UHPC box girder body is strengthened through the transverse bridge to the prestressed tendon to enhance the overall stability; moreover, the overall torsional stiffness can be enhanced by setting the UHPC inner web. With the synergistic effect of various factors, the load on the bridge deck can be well transferred from the UHPC flange to the UHPC box girder body, which is beneficial to reduce the possibility of bridge deck cracking.

Compared with the prior art, the present invention has the advantages of:

1. The large cantilever ultra-wide UHPC box girder unit of the present invention, based on the excellent mechanical properties of UHPC, proposes the structure of the large cantilever ultra-wide UHPC box girder unit, which includes a UHPC box girder body, UHPC cantilever beams and UHPC longitudinal ribs. With the thin-walled structure, the mutual cooperation of each component structure can also greatly increase the rigidity of the box girder flange plate, so that the total width of the box girder can reach 50m, which meets the needs of super large traffic flow and high road grade requirements.

2. The large cantilever and ultra-wide UHPC box girder unit of the present invention has wider UHPC flanges, and is suitable for piers and abutments with small lateral spacing, especially viaducts with tight urban land use and sea-crossing bridges with poor geological conditions at sea.

3. The large cantilever and ultra-wide UHPC box girder unit provided by the present invention is a prefabricated structure using UHPC materials, which can realize the lightweight of the prefabricated structure, make the prefabrication, assembly and transportation of the structure easier, and basically realize the fully assembled construction without on-site The welded steel box girder structure greatly reduces the workload on site and reduces construction risks. Moreover, bridges based on UHPC as the main material can use lighter and thinner plate thickness and structural height than traditional concrete girder bridges, and can be widely used in bridges that require structural clearance (clearance under the bridge, clearance for navigation) , has wide applicability. In addition, the axial tensile strength of the UHPC material used can reach more than 10MPa, which can greatly reduce the size of the bridge structure, reduce the weight of the superstructure, and improve the structure's load resistance efficiency and structural durability. Compared with the steel box girder bridge scheme, It avoids rust removal and cracking of the box girder body in the later stage, reduces operation and maintenance costs in the later stage, and has good economical efficiency.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are For some embodiments of the present invention, those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic structural diagram of the large cantilever ultra-wide UHPC box girder unit in Example 1.

Fig. 2 is a structural schematic diagram of another angle of the large cantilever ultra-wide UHPC box girder unit in Fig. 1.

Fig. 3 is a schematic diagram of the prestressed layout of the large cantilever and ultra-wide UHPC box girder unit in Embodiment 1.

Fig. 4 is a schematic cross-sectional structure diagram of a large cantilever ultra-wide UHPC box girder unit including a UHPC cantilever and a UHPC diaphragm in Example 1.

Fig. 5 is a schematic cross-sectional structure diagram of a large cantilever ultra-wide UHPC box girder unit without UHPC beams and UHPC diaphragms in Example 1.

Fig. 6 is a schematic cross-sectional structure diagram of a large cantilever ultra-wide UHPC box girder unit including UHPC beams and another type of UHPC diaphragm (only UHPC roof stiffeners) in Example 1.

Fig. 7 is a schematic diagram of the layout of the tensile reinforcement of the large cantilever ultra-wide UHPC box girder unit in Example 1.

FIG. 8 is a schematic diagram of the arrangement of tensile reinforcement in Example 1. FIG.

Fig. 9 is a schematic structural view of the large cantilever ultra-wide UHPC box girder bridge in Embodiment 1.

Fig. 10 is a schematic structural view of the large cantilever ultra-wide UHPC box girder unit in Embodiment 2.

Fig. 11 is a schematic diagram of the layout of the second reserved reinforcement, the third reserved reinforcement and prestressed tendons in Embodiment 2.

Fig. 12 is a schematic structural view of the UHPC box girder body in the second embodiment from the side bridge.

FIG. 13 is a schematic structural view of the UHPC cantilever and the side of the UHPC flange in Embodiment 2.

FIG. 14 is a schematic structural diagram of the combination of FIG. 12 and FIG. 13 .

FIG. 15 is a partially enlarged view of A in FIG. 14 .

illustration:

1. Pier; 21. UHPC box girder body; 211. UHPC roof; 212. UHPC inner web; 213. UHPC outer web; 214. UHPC bottom plate; 215. UHPC diaphragm; 22. UHPC beam; 23. UHPC longitudinal rib; 24. UHPC flange; 3. Prestressing system; 31. External prestressing beam; 32. Internal prestressing beam; 33. External beam tooth block; 34. External beam steering block; 4. Tensile reinforcement; 41. First main reinforcement; 42. First end hook; 5. Cast-in-place UHPC wet joint; 51. Upper slope; 52. Lower groove; 6. Second reserved reinforcement; 61. Second main reinforcement; 62. The second end hook; 7, the third reserved reinforcement; 71, the third main reinforcement; 72, the third end hook; 8, the prestressed tendon.

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be described more fully and in detail below in conjunction with the accompanying drawings and preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

Unless otherwise defined, all technical terms used hereinafter have the same meanings as commonly understood by those skilled in the art. The terminology used herein is only for the purpose of describing specific embodiments, and is not intended to limit the protection scope of the present invention.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

Example 1:

As shown in Figures 1-2 and Figures 4-6, the large cantilever and ultra-wide UHPC box girder unit of this embodiment is a prefabricated structure, including a UHPC box girder body 21 and two transverse bridges on the upper surface of the UHPC box girder body 21. There is an outwardly extending UHPC flange 24 on the side, and there are multiple UHPC cantilever beams 22 arranged at intervals between the side of the UHPC box girder body 21 and the bottom surface of the UHPC flange 24 , and there are multiple intervals arranged below the UHPC flange 24 For the UHPC longitudinal ribs 23 arranged, the UHPC beams 22 are arranged along the transverse bridge direction, and the UHPC longitudinal ribs 23 are arranged along the longitudinal bridge direction.

In this embodiment, the UHPC box girder body 21 includes a UHPC top plate 211, a UHPC bottom plate 214, a UHPC transverse diaphragm 215, and a UHPC web plate arranged along the longitudinal bridge direction, all of which are flat plate members, and the UHPC web plate is arranged on the UHPC top plate 211 and the UHPC A box-type structure is formed between the bottom plates 214 (this embodiment shows a single-box double-chamber structure), and the UHPC transverse partition 215 includes UHPC top plate stiffeners, UHPC web stiffeners and UHPC bottom plate stiffeners, UHPC top plate stiffeners The ribs are vertically arranged on the bottom of the UHPC top plate 211 , the UHPC web stiffeners are vertically arranged on the side walls of the UHPC web, and the UHPC bottom plate stiffeners are vertically arranged on the upper part of the UHPC bottom plate 214 .

Specifically, in this embodiment, the UHPC webs include UHPC inner webs 212 and UHPC outer webs 213, the UHPC outer webs 213 are arranged on both sides of the transverse bridge of the box-type structure, and the UHPC inner webs 212 are arranged on the box-type At the center of the longitudinal bridge of the structure, the thickness of the UHPC inner web 212 and the UHPC outer web 213 are both 0.15-0.50m (the above ranges are acceptable, such as 0.2m), and the thickness of the UHPC bottom plate 214 is 0.15-1.20m ( The above range is acceptable, such as 0.2m), the thickness of the UHPC diaphragm 215 is 0.15-0.40m (the above range is acceptable, such as 0.2m), and the UHPC diaphragm 215 is at intervals of 2-6m along the longitudinal bridge direction ( The above-mentioned ranges are acceptable, such as using 3m) to set one, and the height of the UHPC transverse partition 215 is 0.50-1.50m (the above-mentioned ranges are acceptable, such as using 1m).

Of course, as shown in FIG. 6 , according to the actual requirements, in this embodiment, the UHPC transverse partition 215 may only include UHPC roof stiffeners.

As shown in Figures 8 and 9, in this embodiment, the UHPC cantilever 22 is pre-embedded with tensile steel bars 4 extending into the UHPC box girder body 21, and the UHPC diaphragm 215 includes a height not less than that of the UHPC cantilever 22. UHPC roof stiffener, one end of the tensile steel bar 4 is buried in the UHPC cantilever 22, and the other end passes through the UHPC web and extends to the UHPC roof stiffener. Specifically, as shown in Figure 9, in this embodiment, a plurality of tensile reinforcement bars 4 arranged at equal intervals along different heights are pre-embedded at the same UHPC cantilever beam 22, and the tensile reinforcement bars 4 include the first main reinforcement 41 and the The first end hooks 42 at both ends of a main bar 41 are arranged symmetrically along the midpoint of the first main bar 41 , and the first main bars 41 of the upper and lower adjacent tensile steel bars 4 are misplaced.

In this embodiment, the UHPC box girder body 21 has a transverse width of 15-40m, the UHPC flange 24 has a transverse width of 5-10m, and the UHPC flange 24 is symmetrical to the center along the longitudinal bridge of the UHPC box girder body 21. For setting, the UHPC flange 24 is integrally formed with the UHPC box girder body 21 .

In this embodiment, the UHPC cantilever 22 is arranged symmetrically toward the center along the longitudinal bridge, and the size is fixed. The width of the transverse bridge is 5-10m (the above range can be used, such as 8m), the height of the UHPC cantilever 22 is closer to the UHPC box girder body 21, the higher, and the height of the higher side is 2-5m (the above range is all Yes, if 3m is used), the height of the lower side is 0.1-0.6m (the above range is acceptable, such as 0.1m), and the longitudinal distance between the centers of adjacent UHPC cantilever beams 22 is 2-6m (the above-mentioned The range can be used, such as 4m).

In this embodiment, the UHPC longitudinal rib 23 is an inverted trapezoid with a wide top and a narrow bottom. The height of the UHPC longitudinal rib 23 is 0.2-0.8m (the above range is acceptable, such as 0.4m). The width of the upper edge of the UHPC longitudinal rib 23 is 0.3-0.8m (the above range is acceptable, if 0.5m is used), the width of the lower edge is 0.2-0.6m (the above range is acceptable, if 0.4m is used), and the distance between the centers of adjacent UHPC longitudinal ribs 23 is 0.3-1.5m (the above range is acceptable, such as 1.5m).

As shown in Figure 10, the large cantilever ultra-wide UHPC box girder bridge of this embodiment includes pier 1 and a plurality of the above-mentioned large cantilever ultra-wide UHPC box girder units. 3 are assembled and combined into a whole along the longitudinal bridge direction.

Specifically, the large cantilever ultra-wide UHPC box girder bridge in this embodiment is a continuous girder bridge type, and the span layout can be 75m+130m+75m. 3 In the longitudinal direction of the box girder, a mixed stress system of external prestressed beams 31 and internal prestressed beams 32 is adopted. In this embodiment, the axial tensile strength of UHPC is above 10 MPa, and the compressive strength is above 120 MPa.

As shown in Figure 3, in this embodiment, the prestressing system 3 includes internal prestressing beams 32 and external prestressing beams 31, the internal prestressing beams 32 are embedded in the UHPC longitudinal ribs 23 along the longitudinal bridge direction, and the external prestressing beams 31 is set through the UHPC diaphragm 215 along the longitudinal bridge direction. The external prestressed beam 31 is anchored by the integrated external beam tooth block 33 and turned by the integrated external beam steering block 34, which can resist the radial force generated by the external prestressed beam 31 turning. Force, the extracorporeal beam tooth block 33 and the extracorporeal beam steering block 34 are both embedded and fixed on the UHPC diaphragm 215 and consolidated with the inner side wall of the UHPC web. Specifically, in this embodiment, the external prestressing beam 31 is arranged along the UHPC top plate stiffener of the UHPC transverse diaphragm 215 along the longitudinal bridge direction, and the external beam steering block 34 is fixed on the UHPC top plate stiffener and its side surface is connected to the UHPC outer plate stiffener. The web 213 is fixed, and the extracorporeal tooth block 33 is fixed on the stiffener of the UHPC bottom plate and its side is fixed to the UHPC outer web 213 .

The construction method of the large cantilever ultra-wide UHPC box girder bridge of the present embodiment comprises the following steps:

S1: Construction pile foundation and bridge pier 1; large cantilever and ultra-wide UHPC box girder units are prefabricated in the factory;

S2: Install the 0# large cantilever ultra-wide UHPC box girder unit segment on pier 1, and assemble symmetrically on both sides of the installed large cantilever ultra-wide UHPC box girder unit segment according to the sequence of 3 tensions of the prestressed system Other large cantilever ultra-wide UHPC box girder unit segments, and complete the tensioning of the corresponding prestressed system 3;

S3: First close the side spans, then remove the temporary consolidation of the 0# large cantilever ultra-wide UHPC box girder unit segment, and finally close the mid-span, and carry out tensioning of the prestressing system 3 within the entire span of the bridge;

S4: Complete the ancillary works of the large cantilever ultra-wide UHPC box girder bridge and the bridge deck pavement, that is, the construction is completed.

The large cantilever ultra-wide UHPC box girder unit and the large cantilever ultra-wide UHPC box girder bridge provided in this embodiment have light weight and high strength, simple and convenient construction, and reasonable force, which can greatly improve the local stiffness of the box girder flange and provide an ultra-wide bridge deck , has good economy and wide applicability, especially suitable for urban viaducts or cross-river and sea-crossing bridges with navigation clearance requirements.

Example 2:

The large cantilever and ultra-wide UHPC box girder unit of this embodiment is a prefabricated structure, including a UHPC box girder body 21, and UHPC flanges 24 extending outward are provided on both sides of the cross bridge on the upper surface of the UHPC box girder body 21, and the UHPC box girder Between the side of the body 21 and the bottom surface of the UHPC flange 24, there are multiple UHPC beams 22 arranged at intervals, and there are multiple UHPC longitudinal ribs 23 arranged at intervals below the UHPC flange 24. The UHPC beams 22 are arranged along the direction of the transverse bridge. The UHPC longitudinal ribs 23 are arranged along the longitudinal bridge direction.

The structure of UHPC box girder body 21, UHPC flange 24, UHPC cantilever 22 and UHPC longitudinal rib 23 in this embodiment is similar to that of Embodiment 1, the difference is: as shown in Figures 10-15, UHPC flange 24 1. The UHPC cantilever 22 and the UHPC box girder body 21 are connected through a cast-in-place UHPC wet joint 5 , and the upper part of the UHPC box girder body 21 transverse bridge is provided with an upper slope 51 corresponding to the position of the UHPC flange 24 With the lower groove 52 corresponding to the position of the UHPC cantilever 22 , the cast-in-place UHPC in the upper bevel 51 and the lower groove 52 forms a cast-in-place UHPC wet joint 5 .

In this embodiment, the UHPC box girder body 21 is pre-embedded with second reserved steel bars 6 at the upper slant 51 and the lower groove 52, and the second reserved steel bars 6 at the upper slant 51 are evenly provided with multiple pieces. One end is set in the UHPC top plate 211, and the other end extends to the cast-in-place UHPC wet joint 5. The UHPC transverse diaphragm 215 includes a UHPC top plate stiffener with a height not less than the UHPC cantilever 22, and the second pre-set at the lower groove 52 A plurality of steel bars 6 are arranged at equal intervals along different heights, one end is set in the UHPC roof stiffener, and the other end extends to the cast-in-place UHPC wet joint 5; A third reserved steel bar 7 is provided at the corresponding position of the steel bar 6. One end of the third reserved steel bar 7 in the UHPC flange 24 is set in the UHPC flange 24, and the other end extends to the cast-in-place UHPC wet joint 5. The UHPC picks The beam 22 is also provided with a third reserved steel bar 7 at a position corresponding to the second reserved steel bar 6 at the lower groove 52, and one end of the third reserved steel bar 7 in the UHPC cantilever beam 22 is arranged in the UHPC cantilever beam 22, The other end extends into the cast-in-place UHPC wet joint 5 .

In this embodiment, the second reserved reinforcement 6 includes a second main reinforcement 61, and the end of the second main reinforcement 61 close to the cast-in-place UHPC wet joint 5 is provided with a second end hook 62, and the third reserved reinforcement 7 includes a third main reinforcement 71 The end of the third main reinforcement 71 close to the cast-in-place UHPC wet joint 5 is provided with a third end hook 72. The end hooks 72 all cross the center line of the longitudinal bridge of the cast-in-place UHPC wet joint 5 .

In this embodiment, prestressed ribs 8 are arranged along the length of the transverse bridge between the UHPC cantilever beam 22 and the UHPC box girder body 21, and the UHPC transverse diaphragm 215 includes a UHPC top plate whose height is not less than that of the UHPC cantilever beam 22. Stiffeners, the two ends of the prestressed tendons 8 are respectively anchored to the ends of the UHPC cantilever 22, and the middle part of the prestressed tendons 8 passes through the UHPC roof stiffeners.

The large-cantilever ultra-wide UHPC box girder bridge of this embodiment includes pier 1 and the above-mentioned large-cantilever ultra-wide UHPC box girder units, and multiple large-cantilever ultra-wide UHPC box girder units are assembled into a whole through the prestressing system 3 along the longitudinal bridge direction . The prestressing system 3 etc. of the present embodiment can be similar to the embodiment 1.

The construction method of the large cantilever ultra-wide UHPC box girder bridge of the present embodiment comprises the following steps:

S1: Construction pile foundation and bridge pier 1; UHPC box girder body 21 and UHPC cantilever beam (UHPC flange 24 and UHPC cantilever beam 22 are integrally formed) are prefabricated in the factory;

S2: Install the 0# UHPC box girder body section 21 on the pier 1, and assemble other UHPC box girder bodies 21 symmetrically on both sides of the installed UHPC box girder body section 21 according to the sequence of 3 tensions of the prestressing system Sections, according to the order of closing the side spans first and then closing the middle spans, complete the assembly of the 21 sections of the UHPC box girder body, and complete the tensioning of the corresponding prestressing system 3;

S3: Install each UHPC cantilever beam at the specified position on both sides of the UHPC box girder body 21 through temporary constraints, and pour early-strength UHPC to form the cast-in-place UHPC wet joint 5, after the cast-in-place UHPC wet joint 5 reaches a certain strength , tension the prestressed tendons 8 in the direction of the transverse bridge to ensure the connection between the UHPC box girder body 21 and the UHPC cantilever beam 22, and remove the temporary constraints;

S4: Remove the temporary consolidation of the 0# large cantilever ultra-wide UHPC box girder unit segment, and carry out tensioning of the prestressing system 3 within the entire span of the bridge;

S5: Complete the ancillary works of the large cantilever ultra-wide UHPC box girder bridge and the bridge deck pavement, that is, the construction is completed.

Claims (7)

1. The large cantilever ultra-wide UHPC box girder unit is characterized by comprising an UHPC box girder body (21), wherein UHPC flanges (24) extending outwards are arranged on two sides of a transverse bridge on the upper surface of the UHPC box girder body (21), a plurality of UHPC outriggers (22) arranged at intervals are arranged between the side surface of the UHPC box girder body (21) and the bottom surface of the UHPC flange (24), a plurality of UHPC longitudinal ribs (23) arranged at intervals are arranged below the UHPC flange (24), the UHPC outriggers (22) are arranged along the transverse bridge direction, and the UHPC longitudinal ribs (23) are arranged along the longitudinal bridge direction;

the UHPC box girder body (21) comprises an UHPC top plate (211), an UHPC bottom plate (214), an UHPC transverse clapboard (215) and UHPC webs arranged along a longitudinal bridge direction, wherein the UHPC webs are arranged between the UHPC top plate (211) and the UHPC bottom plate (214) to form a box-type structure, the UHPC transverse clapboard (215) comprises at least one of UHPC top plate stiffening ribs, UHPC web stiffening ribs and UHPC bottom plate stiffening ribs, the UHPC top plate stiffening ribs are vertically arranged at the bottom of the UHPC top plate (211), the UHPC web stiffening ribs are vertically arranged at the side walls of the UHPC webs, and the UHPC bottom plate stiffening ribs are vertically arranged at the upper part of the UHPC bottom plate (214);

the UHPC flange (24) and the UHPC box girder body (21) are integrally formed, or the UHPC flange (24), the UHPC cantilever beam (22) and the UHPC box girder body (21) are connected through a cast-in-place UHPC wet joint (5);

when the UHPC flange (24) and the UHPC box girder body (21) are integrally formed, a tensile steel bar (4) extending into the UHPC box girder body (21) is pre-buried in the UHPC outrigger (22), the UHPC transverse diaphragm plate (215) comprises UHPC top plate stiffening ribs with the height not less than that of the UHPC outrigger (22), one end of the tensile steel bar (4) is buried in the UHPC outrigger (22), and the other end of the tensile steel bar penetrates through the UHPC web plate and extends into the UHPC top plate stiffening ribs;

when the UHPC flange (24), the UHPC cantilever beam (22) and the UHPC box girder body (21) are connected through a cast-in-place UHPC wet joint (5), the upper parts of two sides of the transverse bridge of the UHPC box girder body (21) are provided with an upper bevel connection (51) corresponding to the UHPC flange (24) and a lower groove (52) corresponding to the UHPC cantilever beam (22), and the UHPC is cast in place in the upper bevel connection (51) and the lower groove (52) to form the cast-in-place UHPC wet joint (5); and prestressed tendons (8) arranged along the transverse bridge direction to the full length are further arranged between the UHPC outriggers (22) and the UHPC box girder body (21), each UHPC diaphragm plate (215) comprises UHPC top plate stiffening ribs with the height not less than that of each UHPC outrigger (22), two ends of each prestressed tendon (8) are respectively anchored at the end parts of each UHPC outrigger (22), and the middle part of each prestressed tendon (8) penetrates through each UHPC top plate stiffening rib.

2. The large cantilever ultra-wide UHPC box girder unit according to claim 1, wherein the UHPC web plates comprise an UHPC inner web plate (212) and an UHPC outer web plate (213), the UHPC outer web plates (213) are arranged at two sides of the box structure in the transverse direction of the box structure, the UHPC inner web plate (212) is arranged at the center of the box structure in the longitudinal direction of the box structure, the thickness of the UHPC inner web plate (212) and the thickness of the UHPC outer web plate (213) are both 0.15-0.50m, the thickness of the UHPC bottom plate (214) is 0.15-1.20m, the thickness of the UHPC transverse partition plate (215) is 0.15-0.40m, the UHPC transverse partition plates (215) are arranged at intervals of 2-6m in the longitudinal direction, and the height of the UHPC transverse partition plate (215) is 0.50-1.50m.

3. The large-cantilever ultra-wide UHPC box girder unit is characterized in that a plurality of tensile steel bars (4) which are arranged at equal intervals along different heights are pre-buried at the same UHPC cantilever beam (22), each tensile steel bar (4) comprises a first main bar (41) and first end hooks (42) which are arranged at two ends of the first main bar (41), the first end hooks (42) at two ends of the same first main bar (41) are symmetrically arranged along the middle point of the first main bar (41), and the first main bars (41) of the tensile steel bars (4) are vertically adjacent and staggered.

4. The large-cantilever ultra-wide UHPC box girder unit according to claim 1, wherein a plurality of second reserved steel bars (6) are embedded in an upper bevel opening (51) and a lower groove (52) of the UHPC box girder body (21), one end of each of the plurality of second reserved steel bars (6) is arranged in the UHPC top plate (211), the other end of each of the plurality of second reserved steel bars extends into the cast-in-place UHPC wet joint (5), the UHPC transverse partition plate (215) comprises UHPC top plate stiffening ribs with the height not less than that of the cantilever beam (22), the plurality of second reserved steel bars (6) in the lower groove (52) are arranged at equal intervals along different heights, one end of each of the plurality of second reserved steel bars is arranged in the UHPC top plate stiffening ribs, and the other end of each of the plurality of second reserved steel bars extends into the cast-in-place UHPC wet joint (5); a third reserved steel bar (7) is arranged at the position, corresponding to the second reserved steel bar (6) at the upper bevel opening (51), of the UHPC flange (24), one end of the third reserved steel bar (7) in the UHPC flange (24) is arranged in the UHPC flange (24), the other end of the third reserved steel bar extends into the cast-in-situ UHPC wet joint (5), a third reserved steel bar (7) is also arranged at the position, corresponding to the second reserved steel bar (6) at the lower groove (52), of the UHPC cantilever beam (22), one end of the third reserved steel bar (7) in the UHPC cantilever beam (22) is arranged in the UHPC cantilever beam (22), and the other end of the third reserved steel bar extends into the cast-in-situ UHPC wet joint (5);

the second reserved steel bar (6) comprises a second main bar (61), a second end hook (62) is arranged at one end, close to the cast-in-situ UHPC wet joint (5), of the second main bar (61), the third reserved steel bar (7) comprises a third main bar (71), a third end hook (72) is arranged at one end, close to the cast-in-situ UHPC wet joint (5), of the third main bar (71), the second main bar (61) and the third main bar (71) are arranged in a transverse bridge mode in a vertically staggered mode, and the second end hook (62) and the third end hook (72) cross the longitudinal bridge direction center line of the cast-in-situ UHPC wet joint (5).

5. The large cantilever ultra-wide UHPC box girder unit according to any one of claims 1-4, wherein the transverse bridge width of the UHPC box girder body (21) is 15-40m, the transverse bridge width of the UHPC flange (24) is 5-10m, and the UHPC flanges (24) are arranged symmetrically along the longitudinal bridge direction of the UHPC box girder body (21);

the UHPC outriggers (22) are symmetrically arranged along the longitudinal bridge direction, the thickness of the UHPC outriggers (22) is 0.1-0.8m, the transverse bridge direction width of the UHPC outriggers (22) is 5-10m, the height of the UHPC outriggers (22) is higher when being closer to the UHPC box girder body (21), the height of the higher side is 2-5m, the height of the lower side is 0.1-0.6m, and the longitudinal bridge direction distance between the centers of the adjacent UHPC outriggers (22) is 2-6m;

the UHPC longitudinal ribs (23) are inverted trapezoids with wide upper parts and narrow lower parts, the height of the UHPC longitudinal ribs (23) is 0.2-0.8m, the width of the upper edge of each UHPC longitudinal rib (23) is 0.3-0.8m, the width of the lower edge of each UHPC longitudinal rib (23) is 0.2-0.6m, and the transverse bridge distance between the centers of the adjacent UHPC longitudinal ribs (23) is 0.3-1.5m.

6. A large cantilever ultra-wide UHPC box girder bridge is characterized by comprising a bridge pier (1) and large cantilever ultra-wide UHPC box girder units according to any one of claims 1 to 5, wherein a plurality of the large cantilever ultra-wide UHPC box girder units are assembled and combined into a whole along the longitudinal bridge direction through a prestress system (3);

the prestress system (3) comprises internal prestress tendons (32) and external prestress tendons (31), the internal prestress tendons (32) are embedded in the UHPC longitudinal ribs (23) along the longitudinal bridge direction, the external prestress tendons (31) penetrate through the UHPC transverse partition plate (215) along the longitudinal bridge direction, the external prestress tendons (31) are anchored through an integrated external tendon tooth block (33) and turned through an integrated external tendon turning block (34), and the integrated external tendon tooth block (33) and the external tendon turning block (34) are both embedded on the UHPC transverse partition plate (215) and are fixedly connected with the inner side wall of the UHPC web plate.

7. The construction method of the large-cantilever ultra-wide UHPC box girder bridge of claim 6, characterized by comprising the following steps:

s1: constructing a pile foundation and a pier (1);

s2: installing a 0# large cantilever ultra-wide UHPC box girder unit segment on a pier (1), symmetrically assembling other large cantilever ultra-wide UHPC box girder unit segments on two sides of the installed large cantilever ultra-wide UHPC box girder unit segment according to the tensioning sequence of a prestress system (3), and completing the tensioning of the corresponding prestress system (3);

s3: firstly, folding a side span, then removing the temporary consolidation of the 0# large cantilever ultra-wide UHPC box girder unit section, finally folding a mid-span, and tensioning a prestressed system (3) in the full-bridge span;

s4: and (4) completing the auxiliary engineering of the large cantilever ultra-wide UHPC box girder bridge and the bridge deck pavement, namely completing the construction.

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