CN212404773U

CN212404773U - UHPC-NC mixed box girder and large-span rigid frame bridge

Info

Publication number: CN212404773U
Application number: CN202021877094.8U
Authority: CN
Inventors: 邵旭东; 贺耀北
Original assignee: Hunan University
Current assignee: Hunan University
Priority date: 2020-09-01
Filing date: 2020-09-01
Publication date: 2021-01-26
Anticipated expiration: 2030-09-01

Abstract

The utility model discloses UHPC-NC mixed box roof beam and stride the rigid frame bridge greatly discloses a UHPC-NC mixed box roof beam for striding the rigid frame bridge greatly, including UHPC ribbed bottom plate, NC web and NC roof, UHPC ribbed bottom plate pass through the NC web with NC roof rigid coupling becomes one. The utility model also provides a stride rigid frame bridge greatly, including mound top beam section, first roof beam section and second roof beam section, first roof beam section is located the both sides of mound top beam section are just followed mound top beam section symmetry sets up, the second roof beam section is located the outside of first roof beam section is just followed mound top beam section symmetry sets up. The utility model discloses a stride rigid frame bridge greatly is UHPC ribbed slab at the bottom plate in high-pressure stress district, and creep is minimum, almost not have the shrink and have super high compressive strength after the UHPC prefabricated plate high-temperature steam maintenance, has increased the compressive capacity of bottom plate, is showing to reduce creep effect, has significantly reduced the continuous rigid frame bridge later stage of large-span and has downwarped and the risk of fracture.

Description

UHPC-NC mixed box girder and large-span rigid frame bridge

Technical Field

The utility model belongs to the bridge field especially relates to a box girder and rigid frame bridge.

Background

The large-span Prestressed Concrete (PC) rigid frame bridge is a common bridge type with strong spanning capability, good structural integrity, simple and convenient construction, good economy and smooth driving, and becomes a main force bridge type in the span range of 100-250m worldwide.

However, in the process of building and later-stage operation of the large-span PC rigid frame bridge, the defects that the concrete of the box girder cracks seriously and the main span deflects excessively downwards are generally existed, so that the applicability, safety, durability and the like of the bridge structure cannot be effectively guaranteed, the normal use function of the bridge can be influenced in serious conditions, and the defects cannot be effectively solved so far. The problem of cracking and downwarping of large span PC rigid frame bridges has become a recognized worldwide problem. The current research shows that the factors influencing the long-term downward deflection of the rigid frame bridge are many, such as prestress loss, section size, bridge span, concrete self weight and the like, wherein the concrete creep effect is the main reason of the long-term continuous downward deflection of the large-span PC rigid frame bridge span, and a considerable part of the prestress loss is also caused by the concrete creep. However, concrete creep is inherent in concrete and is inevitable, and a large-span PC rigid frame bridge prepared from the concrete inevitably has the problems of cracking and downwarping.

Therefore, how to solve the problem of continuous downwarping and cracking in the span of the large-span PC rigid frame bridge is a technical problem which needs to be solved urgently.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that overcome not enough and the defect mentioned in the above background art, provide one kind can reduce to stride the UHPC-NC hybrid box roof beam of rigid frame bridge girder downwarping and fracture greatly and stride the rigid frame bridge greatly. In order to solve the technical problem, the utility model provides a technical scheme does:

a UHPC-NC mixed box girder for a large-span rigid frame bridge comprises a UHPC ribbed bottom plate, an NC web plate and an NC top plate, wherein the UHPC ribbed bottom plate is fixedly connected with the NC top plate into a whole through the NC web plate. The utility model discloses a main starting point is in order to solve the long-term difficult problem of downwarping, fracture of large-span rigid frame bridge, and downwarping, the very big reason of fracture is the creep effect of ordinary concrete bottom plate, leads to rigidity reduction. The utility model discloses an optimize the bottom plate of UHPC-NC mixing box roof beam, adopt UHPC ribbed bottom plate, through cooperateing with NC web and NC roof, because UHPC does not creep and compressive capacity is stronger, the emergence of the long-term downwarping of large-span rigid frame bridge that can significantly reduce, fracture phenomenon.

In the UHPC-NC hybrid box girder, preferably, the UHPC ribbed floor plate is provided with a plurality of longitudinal ribs and two transverse ribs, the plurality of longitudinal ribs are uniformly arranged on the UHPC ribbed floor plate along a longitudinal bridge direction, and the two transverse ribs are respectively arranged on two sides of the UHPC ribbed floor plate along a transverse bridge direction. The utility model discloses in, the high needs of indulging the rib satisfy the change requirement, because it is big more to be close to mound back timber section compressive stress more, so the section area that needs is also big more, so need increase, the change mode commonly used generally is according to the parabola transition, reduces in proper order, the horizontal rib can with indulge the rib height. The transverse ribs are used for anchoring the first prestressed steel bar; because the UHPC base plate is relatively thin, the longitudinal ribs mainly play a role in strengthening the outer stability of the UHPC surface and also play a role in bearing pressure stress.

In the UHPC-NC hybrid box girder, preferably, anchoring steel bars are arranged on two sides of a transverse bridge of the UHPC ribbed bottom plate, one end of each anchoring steel bar is arranged in the UHPC ribbed bottom plate, and the other end of each anchoring steel bar extends upwards to the NC web. The anchoring steel bar is beneficial to the connection between the UHPC ribbed bottom plate and the NC web plate, and the connection strength between the UHPC ribbed bottom plate and the NC web plate is improved.

As a general technical concept, the utility model provides a stride rigid frame bridge greatly still, including mound top beam section, first beam section and second beam section, first beam section is located the both sides of mound top beam section and edge mound top beam section symmetry sets up, the second beam section is located the outside of first beam section and edge mound top beam section symmetry sets up, first beam section and second beam section all include a plurality of interconnect's case roof beam, the case roof beam of first beam section is foretell UHPC-NC mixed case roof beam, the case roof beam of second beam section is the NC case roof beam. The first beam section is a high-pressure stress section, belongs to the high-pressure stress section in the span range close to the pier top beam section 1/4, the larger the pressure stress close to the pier top beam section is, the lower the pressure stress section is, the second beam section is a low-pressure stress section, and the occurrence of phenomena of downward deflection and cracking of the main beam of the large-span rigid frame bridge can be reduced through reasonable selection of the high-pressure stress section and the low-pressure stress section on the box beam and structural optimization of the UHPC-NC mixed box beam.

In the long-span rigid frame bridge, preferably, adjacent UHPC-NC hybrid box girders are connected by a first anchoring assembly, and the first anchoring assembly includes a first prestressed steel bar and a first fastening piece for being matched with the first prestressed steel bar. And when the adjacent UHPC-NC mixed box beams are connected, a mode of tensioning two ends is adopted.

In the long-span rigid frame bridge, preferably, a through hole is formed in a transverse rib between adjacent longitudinal ribs, and the first prestressed steel bar penetrates through the through hole in the adjacent transverse rib of the adjacent UHPC-NC hybrid box girder and applies a pre-stress to the adjacent UHPC-NC hybrid box girder for fixedly connecting through the first fastening member. Considering simple to operate and the transmission of power, the utility model discloses a set up the through-hole on the cross rib, optimize the position of seting up of through-hole, the first prestressing steel stick of rethread is with adjacent UHPC-NC mixing box roof beam rigid coupling, whole rigid coupling structural design is ingenious, simple structure, construction convenience, it is clear and definite to pass the power route, can guarantee rigid coupling intensity and the reliability between the adjacent UHPC-NC mixing box roof beam, is favorable to guaranteeing the holistic mechanical properties of bridge.

In the above large-span rigid frame bridge, preferably, the UHPC-NC hybrid box girder is connected to the NC box girder through a second anchoring assembly, and the second anchoring assembly includes a second prestressed steel bar and a second fastening member for cooperating with the second prestressed steel bar. When the adjacent UHPC-NC mixed box girder is connected with the NC box girder, a one-end tensioning mode is adopted, the bottom plate of the NC box girder is an embedded anchor end, and the UHPC ribbed bottom plate of the UHPC-NC mixed box girder is a tensioning end.

In the long-span rigid frame bridge, preferably, a through hole is formed in the transverse rib between the adjacent longitudinal ribs, one end of the second prestressed steel bar is anchored on the bottom plate of the NC box girder, and the other end of the second prestressed steel bar penetrates through the through hole and fixedly connects the adjacent UHPC-NC mixed box girder and the NC box girder through the second fastening piece. Because the mechanical properties of the bottom plates of the adjacent UHPC-NC mixed box girder and the adjacent NC box girder are greatly different, the connection mode of the adjacent UHPC-NC mixed box girder and the adjacent NC box girder needs to be reasonably optimized to ensure the connection reliability and stability between the adjacent UHPC-NC mixed box girder and the adjacent NC box girder. The utility model discloses an adopt the second prestressed steel stick, with its one end anchor set firmly in the bottom plate of NC case roof beam, the other end sets firmly on the cross rib of UHPC ribbed bottom plate, can guarantee the rigid coupling intensity and the reliability of UHPC-NC mixed case roof beam and NC case roof beam, is favorable to guaranteeing the holistic mechanical properties of bridge.

In the long-span rigid frame bridge, preferably, the second prestressed steel bars are arranged in a staggered manner in a long form and a short form. The mechanical properties of considering NC are relatively poor, the utility model discloses when connecting UHPC-NC mixed case roof beam and NC case roof beam, the second prestressing steel stick adopts length staggered arrangement, can realize its two high joint strength.

The utility model also provides a construction method of foretell long-span rigid frame bridge, including following step:

s1: prefabricating a UHPC ribbed bottom plate of the UHPC-NC mixed box girder, and synchronously pre-burying anchoring steel bars when prefabricating the UHPC ribbed bottom plate;

s2: a pier top beam section is constructed in a cast-in-place mode, and a second prestressed steel bar is synchronously pre-buried when the pier top beam section is constructed;

s3: symmetrically assembling hanging baskets without bottom moulds on two sides of the pier top beam section by adopting a hanging basket cantilever construction method, placing the UHPC ribbed bottom plate under the support of the hanging baskets, and connecting the UHPC ribbed bottom plate with the pier top beam section by tensioning a second prestressed steel bar between the UHPC ribbed bottom plate and the pier top beam section; pouring an NC web plate and an NC top plate of the UHPC-NC mixed box beam in situ; installing a tension hogging moment early-stage steel bundle;

s4: moving the hanging basket to two sides, placing the UHPC ribbed bottom plates under the support of the hanging basket, and connecting the adjacent UHPC ribbed bottom plates by tensioning a first prestressed steel bar between the adjacent UHPC ribbed bottom plates; pouring an NC web plate and an NC top plate of the UHPC-NC mixed box beam in situ; installing a tension hogging moment early-stage steel bundle; repeating the steps until all UHPC-NC mixed box girders are constructed;

s5: moving the hanging basket to two sides, constructing an NC box girder in a cast-in-place manner, synchronously pre-burying a second prestressed steel bar when constructing the NC box girder, and connecting the UHPC ribbed bottom plate with the NC box girder by tensioning the second prestressed steel bar between the UHPC ribbed bottom plate and the NC box girder;

s6: and continuously adopting a hanging basket cantilever construction method to construct the rest NC box girder, and tensioning the post-stage prestressed steel beam to complete the construction of the large-span rigid frame bridge.

The utility model discloses in, also can adopt the prestressing steel bundle to realize striding well side UHPC-NC mixed case roof beam and NC case roof beam rigid coupling, at this moment, S5-S6 adjust to:

s5: moving the hanging baskets to two sides, and performing cast-in-place construction on an NC box girder to realize the closure of the large-span rigid frame bridge;

s6: and tensioning the post-prestressed steel bundles of the mid-span bottom plate, connecting the UHPC ribbed bottom plate with the NC box girder, and tensioning other post-prestressed steel bundles to finish the construction of the large-span rigid frame bridge.

The ultra-high performance concrete (UHPC) is a cement-based composite material with high bending strength, high toughness and high durability, which is prepared by mixing materials such as cement, mineral admixture, fine aggregate, steel fiber, water reducing agent and the like or dry mixture prepared from the materials with water, and then coagulating and hardening. Compared with common concrete (NC), the UHPC material has ultrahigh compressive strength, rupture strength and toughness, and has little creep and almost no shrinkage after high-temperature steam curing. The utility model discloses introduce high strength, high performance concrete material in striding footpath PC rigid frame bridge greatly, from solving the fundamental problem (the concrete shrink creep) of striding PC rigid frame bridge down warping greatly, reduce the concrete creep effect of structure high-pressure stress district bottom plate by a wide margin, reduce the later stage creep deformation to solve and stride PC rigid frame bridge and stride the well problem of continuously down warping greatly.

Compared with the prior art, the utility model has the advantages of:

1. the utility model discloses a stride rigid frame bridge greatly is UHPC ribbed slab at the bottom plate in high-pressure stress district, and creep is minimum, almost not have the shrink and have super high compressive strength after the UHPC prefabricated plate high-temperature steam maintenance, has increased the compressive capacity of bottom plate, is showing to reduce creep effect, has significantly reduced the continuous rigid frame bridge later stage of large-span and has downwarped and the risk of fracture.

2. The utility model discloses a UHPC takes floor can be prefabricated according to the segmentation of case roof beam segment, and adjacent prefabricated UHPC bottom plate can use the prestressing steel bar to connect, removes the conventional cast in situ concrete die block in high-pressure stress district from, and construction convenience has shortened the time limit for a project.

3. The utility model discloses a through reasonable selection case roof beam in striding the rigid frame bridge greatly, adopt UHPC-NC mixing box roof beam and NC case roof beam combination, bridge durability is better, can control the cost, reduces the case roof beam dead weight to a certain extent, improves the span of rigid frame bridge.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of the general positions of a large-span rigid frame bridge in the embodiment.

FIG. 2 is a schematic sectional view of a UHPC-NC hybrid box girder in an example.

Fig. 3 is a schematic longitudinal bridging end section of the UHPC-NC hybrid box girder in an example (arrangement of first prestressed steel bars).

Fig. 4 is a schematic diagram of the connection of adjacent UHPC ribbed backplanes in an example embodiment.

Fig. 5 is a schematic structural view of the connection of the adjacent UHPC ribbed floors and the floors of NC box beams in an embodiment.

Fig. 6 is a schematic view of another construction of the connection of the adjacent UHPC ribbed floors and the floors of NC box girders in an embodiment.

FIG. 7 is a schematic elevation of the construction of the cantilever hanging basket in the embodiment.

FIG. 8 is a schematic side view of the construction of the cantilever cradle in the embodiment.

Illustration of the drawings:

1. a UHPC ribbed backplane; 2. NC web plate; 3. an NC top plate; 4. longitudinal ribs; 5. a cross rib; 6. anchoring the reinforcing steel bars; 7. a pier top beam section; 8. a first beam section; 9. a second beam section; 10. a first pre-stressed steel bar; 11. a first fastener; 12. a second prestressed steel bar; 13. a second fastener; 14. and (5) hanging a basket.

Detailed Description

To facilitate understanding of the present invention, the present invention will be described more fully and specifically with reference to the accompanying drawings and preferred embodiments, but the scope of the present invention is not limited to the specific embodiments described below.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

Example (b):

as shown in fig. 2-3, the UHPC-NC hybrid box girder for a large-span rigid frame bridge of the present embodiment includes a UHPC ribbed bottom plate 1, an NC web 2 and an NC top plate 3, wherein the UHPC ribbed bottom plate 1 is fixedly connected with the NC top plate 3 into a whole through the NC web 2.

In this embodiment, the UHPC ribbed bottom plate 1 is provided with a plurality of longitudinal ribs 4 and two transverse ribs 5, the plurality of longitudinal ribs 4 are uniformly arranged on the UHPC ribbed bottom plate 1 along the longitudinal bridge direction, and the two transverse ribs 5 are respectively arranged on two sides of the UHPC ribbed bottom plate 1 along the transverse bridge direction. In the embodiment, the transverse bridge width of the UHPC ribbed bottom plate 1 is 6m, the thickness is 30cm, the longitudinal ribs 4 are arranged on the UHPC ribbed bottom plate, the transverse bridge width of the longitudinal ribs 4 is 25cm, the UHPC ribbed bottom plate is arranged at a distance of 37.5cm, the height of the UHPC ribbed bottom plate is changed from the beam sections 1# -13#, 1# -13' #, and 90cm to 30cm according to a parabola. The transverse ribs 5 are as high as the longitudinal ribs 4, and the longitudinal bridge width is 30 cm.

In this embodiment, the two lateral sides of the transverse bridge of the UHPC ribbed bottom plate 1 are provided with anchoring steel bars 6, one end of each anchoring steel bar 6 is arranged in the UHPC ribbed bottom plate 1, and the other end of each anchoring steel bar extends upwards to the NC web 2.

As shown in fig. 1, the long-span rigid frame bridge of this embodiment includes a pier top beam section 7, a first beam section 8 and a second beam section 9, where the first beam section 8 is located on two sides of the pier top beam section 7 and symmetrically disposed along the pier top beam section 7, the second beam section 9 is located on the outer side of the first beam section 8 and symmetrically disposed along the pier top beam section 7, the first beam section 8 and the second beam section 9 both include a plurality of interconnected box girders, the box girder of the first beam section 8 is the UHPC-NC hybrid box girder, and the box girder of the second beam section 9 is an NC box girder.

In this embodiment, the span diameter of the large-span rigid frame bridge is arranged to be 115+220+115m, the bridge width is 12m, the pier top beam section 7 is a 0# beam section, and the length of the beam section is 3-4.5 m. The beam sections (first beam sections 8) bearing large compressive stress (1 # -13#, 1# -13' # adopt UHPC-NC mixed box beams, and the application range of the UHPC-NC mixed box beams is that two sides of the pier top beam section 7 are 45m respectively. In addition, the rest low-pressure stress beam sections (the second beam section 9) are all NC box beams. And the combined surface of the UHPC-NC mixed box girder and the NC box girder is arranged on the end surfaces of the 13# and 13' # girder sections.

In the present embodiment, as shown in fig. 4, adjacent UHPC-NC hybrid box girders are connected by a first anchoring assembly, which includes a first prestressed steel bar 10 and a first fastening member 11 for cooperating with the first prestressed steel bar 10. And through holes are formed in the transverse ribs 5 between the adjacent longitudinal ribs 4, and the first prestressed steel bar 10 penetrates through the through holes in the adjacent transverse ribs 5 of the adjacent UHPC-NC mixed box girder and applies prestress to the adjacent UHPC-NC mixed box girder for fixedly connecting through the first fastening piece 11. In this embodiment, 8 high strength prestressed threaded steel rods with a diameter of 50 mm are used as the first prestressed steel rods 10.

In the present embodiment, as shown in fig. 5, the UHPC-NC hybrid box girder and the NC box girder are connected by a second anchoring assembly, which includes a second prestressed steel bar 12 and a second fastening member 13 for cooperating with the second prestressed steel bar 12. And a through hole is formed in the transverse rib 5 between the adjacent longitudinal ribs 4, one end of a second prestressed steel bar 12 is anchored on the bottom plate of the NC box girder, and the other end of the second prestressed steel bar penetrates through the through hole and fixedly connects the adjacent UHPC-NC mixed box girder and the NC box girder through a second fastening piece 13. In this embodiment, 8 high-strength prestressed threaded steel rods with a diameter of 50 mm are used as the second prestressed steel rods 12.

In the embodiment, in order to strengthen the connection between the prefabricated UHPC ribbed bottom plate 1 and the cast-in-place NC bottom plates of 0#, 14#, and 14' and avoid tensile stress, 8 high-strength prestressed threaded steel bars are also arranged between the longitudinal ribs 4, one end of each high-strength prestressed threaded steel bar is embedded into the NC bottom plate, the other end of each high-strength prestressed threaded steel bar is anchored on the transverse rib 5 of the beam section of the prefabricated UHPC ribbed bottom plate, and tensioning is only carried out at the transverse rib 5. Considering that the NC mechanical property is poor, the high-strength prestressed threaded steel bars are arranged at intervals in a long form and a short form on the NC side, and the staggered length is 2-3 m.

As shown in fig. 7 and 8, the embodiment further provides a construction method of the long-span rigid frame bridge, which includes the following steps:

s1: prefabricating a UHPC ribbed bottom plate 1 of the UHPC-NC mixed box girder, and synchronously pre-burying an anchoring steel bar 6 when prefabricating the UHPC ribbed bottom plate 1;

s2: a pier top beam section 7(0#) for cast-in-place construction is constructed, and a second prestressed steel bar 12 is synchronously pre-buried when the pier top beam section 7 is constructed; namely, completing construction with the 0# section;

s3: symmetrically assembling hanging baskets 14 without bottom moulds at two sides of the pier top beam section 7 by adopting a hanging basket cantilever construction method, placing the UHPC ribbed bottom plate 1 under the support of the hanging baskets 14, and connecting the UHPC ribbed bottom plate 1 with the pier top beam section 7 by tensioning a second prestressed steel bar 12 between the UHPC ribbed bottom plate 1 and the pier top beam section 7; an NC web 2 and an NC top plate 3 of the UHPC-NC mixed box beam are cast in situ; installing a tension hogging moment early-stage steel bundle when the strength of the common concrete for pouring the NC top plate 3 and the NC web 2 reaches more than 90% of the design strength; namely, the construction with sections 1# and 1' # is completed;

s4: moving the hanging basket 14 to two sides, placing the UHPC ribbed bottom plates 1 under the support of the hanging basket 14, and connecting the adjacent UHPC ribbed bottom plates 1 by tensioning a first prestressed steel bar 10 between the adjacent UHPC ribbed bottom plates 1; an NC web 2 and an NC top plate 3 of the UHPC-NC mixed box beam are cast in situ; installing a tension hogging moment early-stage steel bundle; repeating the steps until all UHPC-NC mixed box girders are constructed; thus completing construction of 2# -13#, 2# -13' #;

s5: moving the hanging baskets 14 to two sides, constructing an NC box girder in a cast-in-place manner, synchronously pre-burying a second prestressed steel bar 12 when constructing the NC box girder, and connecting the UHPC ribbed bottom plate 1 with the NC box girder by tensioning the second prestressed steel bar 12 between the UHPC ribbed bottom plate 1 and the NC box girder; namely, the construction of sections 14# and 14' # is completed;

s6: and (5) continuing to adopt the hanging basket 14 cantilever construction method to construct the rest NC box girder, namely completing the construction of the long-span rigid frame bridge.

As shown in fig. 6, in this embodiment, the connection between the UHPC ribbed floor 1 and the 14#, 14' cast-in-place NC floor can also be performed by using an elongated post-prestressed steel beam spanning the mid-span floor to the cross rib 5 of the beam section of the UHPC ribbed floor 1, and tensioning is performed at the cross rib 5.

In this embodiment, the prefabricated UHPC ribbed bottom plate 1 is used for 1# -13#, 1 '-13' # so that the bottom die required by the conventional cradle 14 can be omitted. After the UHPC ribbed bottom plate 1 is prefabricated and the high-strength prestressed threaded steel bar is connected, the UHPC ribbed bottom plate is supported on a hanging basket 14, and the cast-in-place NC top plate 3 and the NC web plate 2 can bear the reinforcing steel bar and NC wet weight.

Claims

1. A UHPC-NC mixed box girder for a large-span rigid frame bridge is characterized by comprising a UHPC ribbed bottom plate (1), an NC web plate (2) and an NC top plate (3), wherein the UHPC ribbed bottom plate (1) is fixedly connected with the NC top plate (3) into a whole through the NC web plate (2).

2. A UHPC-NC mixing box girder according to claim 1, characterized in that a plurality of longitudinal ribs (4) and two transverse ribs (5) are arranged on the UHPC ribbed bottom plate (1), the longitudinal ribs (4) are uniformly arranged on the UHPC ribbed bottom plate (1) along the longitudinal bridge direction, and the transverse ribs (5) are respectively arranged on two sides of the UHPC ribbed bottom plate (1) along the transverse bridge direction.

3. A UHPC-NC hybrid box girder according to claim 1 or 2, characterised in that the transversal bridge of the UHPC ribbed bottom plate (1) is provided with anchoring bars (6) on both sides, one end of the anchoring bar (6) being arranged in the UHPC ribbed bottom plate (1) and the other end extending up into the NC web (2).

4. A large-span rigid frame bridge, which is characterized by comprising a pier top beam section (7), a first beam section (8) and a second beam section (9), wherein the first beam section (8) is positioned on two sides of the pier top beam section (7) and symmetrically arranged along the pier top beam section (7), the second beam section (9) is positioned on the outer side of the first beam section (8) and symmetrically arranged along the pier top beam section (7), the first beam section (8) and the second beam section (9) both comprise a plurality of interconnected box girders, the box girder of the first beam section (8) is the UHPC-NC mixed box girder of claim 2 or 3, and the box girder of the second beam section (9) is an NC box girder.

5. The long-span rigid frame bridge of claim 4, characterized in that adjacent UHPC-NC hybrid box girders are connected by a first anchoring assembly, wherein the first anchoring assembly comprises a first prestressed steel bar (10) and a first fastener (11) for cooperating with the first prestressed steel bar (10).

6. The long-span rigid frame bridge of claim 5, wherein the transverse ribs (5) between the adjacent longitudinal ribs (4) are provided with through holes, and the first prestressed steel bar (10) passes through the through holes on the adjacent transverse ribs (5) of the adjacent UHPC-NC mixed box girder and is fixedly connected with the adjacent UHPC-NC mixed box girder by applying prestress through the first fastening piece (11).

7. The large-span rigid frame bridge according to any one of claims 4 to 6, wherein the UHPC-NC hybrid box girder and the NC box girder are connected by a second anchoring assembly, and the second anchoring assembly comprises a second prestressed steel bar (12) and a second fastening member (13) for cooperating with the second prestressed steel bar (12).

8. The long-span rigid frame bridge of claim 7, wherein through holes are formed in the transverse ribs (5) between the adjacent longitudinal ribs (4), one end of the second prestressed steel bar (12) is anchored on the bottom plate of the NC box girder, and the other end of the second prestressed steel bar passes through the through holes and fixedly connects the adjacent UHPC-NC mixed box girder and the NC box girder through the second fastening piece (13).

9. The long-span rigid frame bridge according to claim 7, characterized in that the second prestressed steel bars (12) are arranged in a staggered manner in a long form and a short form.