CN217896174U - Continuous box girder bridge of prestressing force UHPC-NC mixed system - Google Patents

Abstract

The utility model provides a continuous box girder bridge of prestressing force UHPC-NC mixed system, including UHPC-NC combination box girder segment section, PC box girder segment section and vertically adopt the prestressing force system of whole external prestressing force or partial external prestressing force, UHPC-NC combination box girder segment section include the UHPC bottom plate of prefabricated construction and support in the cast-in-place structure NC box girder of UHPC bottom plate, UHPC-NC combination box girder segment section is located the support pier top region, and its length is 1/4 ~ 1/3 of main span length, PC box girder segment section is located the region except that UHPC-NC combination box girder segment section. The utility model provides an adopt UHPC-NC integrated configuration at mound back timber section, all the other sections adopt PC case girder construction, and the atress is good, the dead weight is lighter, can effectively restrain the main span and warp down, can reuse the sufficient old bridge pier abutment of bearing capacity again simultaneously, and technical requirement is low, economic nature is good.

Description

Continuous box girder bridge of prestressing force UHPC-NC mixed system

Technical Field

The utility model relates to a bridge engineering technical field, concretely relates to continuous case girder bridge of prestressing force UHPC-NC mixed system.

Background

The Prestressed Concrete (PC) continuous box girder bridge has the advantages of high torsional rigidity, simple and convenient construction, good economy and the like, and is widely applied to the field of bridges. However, in the service process of the bridge, under the action of the negative bending moment, the top compressive stress of the main beam is small and the bottom compressive stress of the main beam is large, and in view of the obvious shrinkage creep effect of common concrete (NC), the creep curvature of the beam section of the bridge in the pier top area is large (the deformation of the beam top is small and the deformation of the beam bottom is large), so that the main span of the bridge is excessively downwarped. Therefore, the conventional PC continuous box girder bridge inevitably has excessive main span sag during operation, limited by the material properties of the NC itself.

Ultra-High Performance Concrete (UHPC) is a fiber reinforced cement-based composite material with ultrahigh strength, ultrahigh toughness, high durability and good volume stability. The shrinkage of the UHPC structure after high-temperature steam curing is almost zero, the structure is compact and the porosity is low, so that the creep coefficient of the UHPC is only 0.15-0.2 of that of common concrete. In addition, the UHPC has high mechanical property and ultrahigh elastic modulus, and can well meet the requirements of bridge engineering materials. If the hogging moment beam section at the top of the PC continuous box girder bridge pier adopts a UHPC-NC combined structure (the bottom plate part adopts UHPC materials), the low-shrinkage and low-creep characteristics of the UHPC can reduce the creep curvature of the beam section in the pier top area to a certain extent, and further avoid excessive downward deflection of the main span of the bridge. Consequently, when the UHPC material of light, high strength has been adopted to continuous box girder bridge scheme, superstructure overall mass is lighter than the traditional PC continuous girder bridge of equal stride, to the PC continuous girder bridge that partly needs the rebuild because of the excessive downwarping of main span, the construction unit can adopt this mixed system bridge type after carrying out reasonable aassessment to existing abutment, this not only improves the bulk rigidity of new bridge, avoid operating the excessive downwarping of main span appearing after several years, can also reuse original abutment, reduce reconstruction scheme cost by a wide margin.

In the prior art, a bridge system with a UHPC-NC structure on the pier top is also available, but in the actual reconstruction of bridge type scheme selection, because partial sections of the bridge adopt full UHPC box girder sections, the construction cost of the upper structure is greatly improved, and the original technical scheme has no competitiveness. In addition, the prefabrication, transportation and hoisting of the UHPC box girder segment have extremely high requirements on prefabrication conditions, transportation road conditions, hoisting equipment and the like, and the requirements on high technology and equipment are difficult to meet in most areas. Therefore, for some regions, it is not desirable to use all UHPC box beam segments for the rebuilt bridge model, both from an economic perspective and from a realistic perspective.

The prior art discloses a prestressed UHPC-NC combined continuous box girder bridge and a construction method thereof (Chinese patent application CN 114197321A), the bridge comprises 3 types of girder sections which are respectively a PC box girder section, a UHPC-NC combined box girder section and a full UHPC box girder section, the full UHPC box girder section has light weight and high strength, an integrally prefabricated and assembled assembly type construction method can be adopted, the construction period can be greatly shortened, the downwarping and cracking of the traditional continuous system bridge are solved, the suitable span of the bridge is improved, and the reconstruction problem of the continuous system bridge which needs to be dismantled and reconstructed due to excessive downwarping and girder cracking is not solved.

In view of the above, there is a need to provide a new bridge structure to solve the above-mentioned technical problems.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is to provide a continuous box girder bridge of prestressing force UHPC-NC mixed system adopts UHPC-NC integrated configuration at the mound back timber section, and all the other sections adopt PC box girder construction, and the atress is good, the dead weight is lighter, can effectively restrain the main span and warp down, can the sufficient old bridge pier abutment of reuse bearing capacity simultaneously again, and technical requirement is low, economic nature is good.

In order to solve the above problem, the technical scheme of the utility model is as follows:

a continuous box girder bridge with a prestressed UHPC-NC mixed system comprises UHPC-NC combined box girder segments, PC box girder segments and a prestressed system which adopts full external prestress or partial external prestress in the longitudinal direction, wherein each UHPC-NC combined box girder segment comprises a UHPC bottom plate with a prefabricated structure and an NC box girder with a cast-in-place structure supported on the UHPC bottom plate, each UHPC-NC combined box girder segment is positioned in the top area of a support pier, the length of each UHPC-NC combined box girder segment is 1/4-1/3 of the main span length, and each PC box girder segment is positioned in an area except the UHPC-NC combined box girder segment.

The NC box girder comprises a first top plate, a first web plate, a first bottom plate and a first diaphragm plate, wherein the first top plate and the first web plate of the NC box girder are both flat plate members, the first bottom plate of the NC box girder is a short rib plate member, and the first diaphragm plate of the NC box girder consists of at least one of a first top plate stiffening rib, a first web plate stiffening rib and a first bottom plate stiffening rib;

the UHPC bottom plate is a short rib plate member, the NC box girder is arranged on the UHPC bottom plate, the UHPC bottom plate and the first bottom plate of the NC box girder are connected into a whole through reserved steel bars of the UHPC bottom plate, and the reserved steel bars are arranged in parallel along the bridge direction and the transverse bridge direction.

Furthermore, the UHPC bottom plate is a short rib plate member consisting of a flat plate and longitudinal ribs, wherein the thickness of the flat plate is 0.12-1.50 m, the height of the longitudinal ribs is 0.10-0.50 m, the width of the upper edges of the longitudinal ribs is 0.10-0.30 m, the width of the lower edges of the longitudinal ribs is 0.12-0.32 m, and the center distance between adjacent longitudinal ribs is 0.30-1.50 m;

the first top plate, the first web plate, the first bottom plate and the first diaphragm plate of the NC box girder are all thick members, wherein the thickness of the first top plate is 0.25-1.50 m, the thickness of the first web plate is 0.40-2.50 m, the thickness of the first bottom plate is 0.28-2.50 m, and the thickness of the first diaphragm plate is 1.50-4.00 m.

Furthermore, the PC box girder segment comprises a second top plate, a second bottom plate, a second web plate and a second diaphragm plate, the thickness of the second top plate is 0.25-1.50 m, the thickness of the second web plate is 0.40-2.50 m, the thickness of the second diaphragm plate is 1.50-4.00 m, and the thickness of the second bottom plate is 0.50-4.00 m.

Further, a rigidity transition section is arranged between the UHPC-NC combined box girder segment and the PC box girder segment, the rigidity transition section is of a UHPC-NC combined structure and comprises a transition section NC box girder and a transition section UHPC bottom plate, the transition section NC box girder comprises a third top plate, a third web plate and a third bottom plate, the third top plate and the third web plate of the transition section NC box girder are both flat plate members, and the third bottom plate of the transition section NC box girder is a short rib plate member; a third top plate, a third web plate and a third bottom plate of the transition section NC box girder are all thick members, wherein the thickness of the third top plate is 0.25-1.50 m, the thickness of the third web plate is 0.40-2.50 m, and the thickness of the third bottom plate is 0.28-2.50 m;

the transition section UHPC bottom plate is a short rib plate member consisting of a flat plate and longitudinal ribs, wherein the thickness of the flat plate is 0.12-1.50 m, the height of the longitudinal ribs is 0.10-0.50 m, the width of the upper edges of the longitudinal ribs is 0.10-0.30 m, the width of the lower edges of the longitudinal ribs is 0.12-0.32 m, and the center distance between adjacent longitudinal ribs is 0.30-1.50 m.

Further, the thicknesses of the two ends of a third top plate and a third web plate of the rigidity transition section are respectively corresponding to the structural thicknesses of the adjacent UHPC-NC combined box girder segment and the adjacent PC box girder segment; the total thickness of two ends of the third bottom plate of the rigidity transition section is respectively the same as the total thickness of the bottom plate of the adjacent UHPC-NC combined box girder segment and the thickness of the bottom plate of the PC box girder segment, and the thickness of the UHPC bottom plate of the rigidity transition section is gradually reduced from the UHPC-NC combined box girder segment to the PC box girder segment.

Furthermore, the prestress system comprises an in-vivo prestress structure and an in-vitro prestress structure which are arranged on the UHPC-NC combined box girder segment and the PC box girder segment, and the anchoring and steering of the in-vivo prestress structure and the in-vitro prestress structure are both positioned at the corresponding diaphragm plate.

Further, the continuous box girder bridge of the prestressed UHPC-NC mixed system is of a continuous rigid frame bridge type or a continuous girder bridge type.

Further, the continuous box girder bridge of the prestressed UHPC-NC mixed system is a reconstruction bridge.

Further, the span of the continuous box girder bridge of the prestressed UHPC-NC mixed system is arranged to be 60m +110m +60m.

Compared with the prior art, the utility model provides a continuous case girder bridge of prestressing force UHPC-NC mixed system, beneficial effect lies in:

1. the utility model provides a continuous box girder bridge of prestressing force UHPC-NC mixed system adopts UHPC-NC integrated configuration at mound top region festival section, and all the other festival sections adopt PC box girder structure, based on UHPC light, the characteristics that excel in and the low shrink creep, can reduce box girder plate thickness by a wide margin, reduce superstructure weight, improve the long-term rigidity of structure, reduce bridge structures creep and shrink by a wide margin, can avoid the bridge owner to stride from the root and excessively downwarp.

2. The utility model provides a continuous case girder bridge of prestressing force UHPC-NC mixed system, the prefabricated construction all adopts UHPC material, can realize the lightweight of prefabricated construction, makes superstructure's prefabrication, transportation, installation easier, this theory that accords with quick construction bridge; meanwhile, the pier top area section adopts a method combining prefabrication and cast-in-place, so that the requirement of hoisting equipment can be reduced, and the construction risk is reduced; and other segments adopt cast-in-place PC box girder structures and adopt a cantilever pouring mode, so that the technical requirements and the equipment requirements are lower.

3. The utility model provides a continuous box girder bridge of prestressing force UHPC-NC mixed system, the dead weight is lighter, to the part because of the main span excessively downwarping the PC continuous beam bridge that needs the rebuild urgently, the construction unit can adopt this mixed system bridge type after carrying out reasonable aassessment to existing abutment, this not only improves the bulk rigidity of new bridge, the main span excessively downwarping appears after avoiding operating several years, can also reuse original abutment, reduce the reconstruction scheme cost by a wide margin. Therefore, the utility model discloses a continuous box girder bridge of prestressing force UHPC-NC mixed system is an extremely competitive rebuild bridge type scheme.

4. Compared with the prior art (Chinese patent application CN 114197321A), the utility model discloses a to need to demolish the continuous system bridge of rebuilding because of excessive downwarping and roof beam body fracture, under the prerequisite that its existing pier of aassessment has sufficient bearing capacity, the novel mixed system continuous beam bridge that provides. The bridge type comprises two types of box girder segments which are respectively a PC box girder segment and a UHPC-NC box girder segment, and does not adopt a full UHPC box girder segment, on one hand, the reconstructed bridge type does not have the requirement of lifting the span, and compared with the traditional PC box girder bridge with the same span, because the UHPC-NC box girder segment is introduced, the bridge type can improve the rigidity of a bridge body and reduce the weight of an upper structure of the bridge, not only can meet the requirement of reconstructing the bridge type to a certain extent, but also has competitive economy; on the other hand, the prefabrication, transportation and hoisting of the full UHPC box girder segment have extremely high requirements on manufacturing process, transportation road conditions, hoisting equipment and the like, and the requirements on high technology, good road conditions and equipment are difficult to meet in most of areas needing bridge reconstruction. Therefore, for most areas, both from an economic perspective and from a realistic standpoint, it is not desirable to employ all UHPC box girder segments and their prefabricated, assembled construction methods to reconstruct the bridge.

Drawings

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

FIG. 1 is a schematic structural diagram of an embodiment 1 of a continuous box girder bridge of a prestressed UHPC-NC mixed system according to the utility model;

FIG. 2 is a schematic diagram of a prestressed tendon structure of a prestressed UHPC-NC hybrid system continuous box girder bridge of the present invention;

fig. 3 is a schematic structural diagram of a pier top UHPC-NC combined box girder segment in the continuous box girder bridge of the prestressed UHPC-NC mixed system of the present invention;

FIG. 4 is a schematic structural diagram of a UHPC-NC combined box girder segment in a 1/2 pier top area in the continuous box girder bridge of the prestressed UHPC-NC mixed system of the utility model;

FIG. 5 is a schematic diagram of the UHPC-NC combined box girder segment prestress arrangement in the continuous box girder bridge of the prestress UHPC-NC mixed system of the utility model;

FIG. 6 is a schematic structural diagram of a PC box girder segment in a continuous box girder bridge of a prestressed UHPC-NC mixed system according to the present invention;

fig. 7 is a schematic structural view of a middle pier top UHPC-NC box girder segment, a PC box girder segment and a rigidity transition section of the present invention;

FIG. 8 is a schematic structural view of a middle stiffness transition section of the present invention;

FIG. 9 isbase:Sub>A schematic cross-sectional view taken along line A-A of FIG. 1;

FIG. 10 is a schematic cross-sectional view taken at B-B in FIG. 1;

FIG. 11 is an enlarged view of portion A of FIG. 10;

FIG. 12 is a schematic view of the cross-sectional structure C-C of FIG. 11;

fig. 13 is a schematic structural diagram of the continuous box girder bridge of the pre-stressed UHPC-NC hybrid system of the present invention in example 2.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the embodiments of the present invention and make the above objects, features and advantages of the present invention more obvious and understandable, the following description will make further description of the embodiments of the present invention.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual values, and between the individual values may be combined with each other to yield one or more new ranges of values, which ranges of values should be considered as specifically disclosed herein.

Example 1

Referring to fig. 1-12 in combination, the prestressed UHPC-NC hybrid system continuous box girder bridge of the present embodiment is a continuous bridge type, and the span is arranged to be 60m +110m +60m, and includes a pier 1, a UHPC-NC combined box girder segment 2, a PC box girder segment 3, and a prestressed system 4; the UHPC-NC combined box girder segment 2 is arranged on the pier top girder segment, the length of the UHPC-NC combined box girder segment is 1/4-1/3 of the length of the main span, the PC box girder segment 3 is arranged in the area except the UHPC-NC combined structure, and the prestress system 4 adopts an external prestress and internal prestress mixed stress system in the longitudinal direction of the box girder. In this example, the bending tensile strength of UHPC was 20MPa or more and the compressive strength was 120MPa or more.

The UHPC-NC combined box girder segment 2 comprises a UHPC bottom plate 21 and an NC box girder 22 supported on the UHPC bottom plate 21, wherein the NC box girder 22 comprises a first top plate 221, a first web plate 222, a first bottom plate 223 and a first diaphragm plate 224, the first top plate 221 and the first web plate 222 of the NC box girder are both flat plate members, the first bottom plate 223 of the NC box girder 22 is a short rib plate member, and the first diaphragm plate 224 of the NC box girder is composed of at least one of a first top plate 221 stiffening rib, a first web plate 222 stiffening rib and a first bottom plate 223 stiffening rib.

In this embodiment, the UHPC floor 21 is a short rib plate member, and the NC box girder 22 is placed on the UHPC floor 21. Specifically, the UHPC bottom plate 21 is a prefabricated plate, the NC box girder 22 is a cast-in-place structure, the UHPC bottom plate 21 and a first bottom plate 223 of the NC box girder 22 are connected into a whole through UHPC bottom plate reserved steel bars, and the reserved steel bars are arranged in parallel along the bridge direction and the transverse bridge direction.

In this embodiment, the UHPC board 21 is a short rib plate member composed of a flat plate and longitudinal ribs, wherein the flat plate has a thickness of 0.12m to 1.50m, the longitudinal ribs have a height of 0.10m to 0.50m, the upper edges of the longitudinal ribs have a width of 0.10m to 0.30m, the lower edges of the longitudinal ribs have a width of 0.12m to 0.32m, and the center distance between adjacent longitudinal ribs is 0.30m to 1.50m. The pier top prefabricated UHPC bottom plate 21 with the structure size can be used as a bottom template of a cast-in-place NC structure, and can ensure rigidity and stability in construction.

The first top plate 221, the first web 222, the first bottom plate 223 and the first diaphragm plate 224 of the NC box girder 22 are all thick members, wherein the thickness of the first top plate 221 is 0.25m to 1.50m, the thickness of the first web 222 is 0.40m to 2.50m, the thickness of the first bottom plate 223 is 0.28m to 2.50m, and the thickness of the first diaphragm plate 224 is 1.50m to 4.00m. By adopting the structure size, the stress of the pier top NC structure can be reduced, and the cracking risk is reduced; the bottom of the UHPC-NC combined box girder segment 2 is a UHPC ribbed bottom plate, and the upper part is a cast-in-situ NC segment; the reserved steel bars are connected into a whole through the UHPC ribbed bottom plate, and the reserved steel bars are arranged in parallel along the bridge direction and the transverse bridge direction, so that the common stress between the UHPC and the NC can be ensured.

In this embodiment, the PC box girder segment 3 includes a second top plate 31, a second bottom plate 32, a second web plate 33 and a second diaphragm plate 34, the thickness of the second top plate is 0.25m to 1.50m, the thickness of the second web plate is 0.40m to 2.50m, the thickness of the second diaphragm plate is 1.50m to 4.00m, and the thickness of the second bottom plate is 0.28m to 2.50m.

In this embodiment, the prestressed system 4 includes external prestressed tendons 41 and internal prestressed tendons 42 provided in the UHPC-NC combined box girder segment 2 and the PC box girder segment 3. The internal prestressing tendons 42 are embedded in the first top plate 221 and the stiffening ribs of the top plate; the external prestressed tendons 41 pass through the first diaphragm 224 and are anchored by the external tendon tooth blocks 43. The external binding tooth block 43 is embedded between the first diaphragm plates 224 and is fixedly connected with the inner wall of the second web plate 33. Further, a tendon turning block 44 is further provided in the segment, and the external tendon 41 is turned by the tendon turning block 44 to resist a radial force generated by turning the external tendon 41. The tendon-turning block 44 is embedded in the first web 222 side plate, and one surface of the tendon-turning block is fixedly connected with the inner wall of the box girder.

In the embodiment, in order to improve the structural stability, a rigidity transition section 6 is arranged between the UHPC-NC combined box girder segment 2 and the PC box girder segment 3. The rigidity transition section 6 is a UHPC-NC combined box girder segment, and comprises a transition section NC box girder 61 and a transition section UHPC bottom plate 62, wherein the transition section NC box girder comprises a third top plate 611, a third web plate 612 and a third bottom plate 613, the third top plate 611 and the third web plate 612 of the transition section NC box girder are both flat plate members, and the third bottom plate 613 of the transition section NC box girder is a short rib plate member. The third top plate 611, the third web plate 612 and the third bottom plate 613 of the transition section NC box girder are all thick members, wherein the thickness of the third top plate 611 is 0.25 m-1.50 m, the thickness of the third web plate 612 is 0.40 m-2.50 m, and the thickness of the third bottom plate 613 is 0.28 m-2.50 m.

The transition section UHPC bottom plate 62 is a short rib plate component consisting of a flat plate and longitudinal ribs, wherein the thickness of the flat plate is 0.12-1.50 m, the height of the longitudinal ribs is 0.10-0.50 m, the width of the upper edges of the longitudinal ribs is 0.10-0.30 m, the width of the lower edges of the longitudinal ribs is 0.12-0.32 m, and the center distance between adjacent longitudinal ribs is 0.30-1.50 m.

The thicknesses of the two ends of a third top plate and a third web plate of the rigidity transition section 6 are respectively and correspondingly the same as the structural thicknesses of the adjacent UHPC-NC combined box girder segment and the PC box girder segment; the total thickness of two ends of the third bottom plate is respectively the same as the total thickness of the bottom plate in the adjacent UHPC-NC combined box girder segment and the thickness of the bottom plate of the PC box girder segment, and the thickness of the UHPC bottom plate in the transition section is gradually reduced from the UHPC-NC combined box girder segment to the PC box girder segment. Specifically, the thickness of the bottom plate of the rigidity transition section 6 close to one end of the UHPC-NC combined box girder segment is the same as the total thickness of the UHPC bottom plate and the NC bottom plate in the UHPC-NC combined box girder segment, and the thickness of the bottom plate close to one end of the PC box girder segment 3 is the same as that of the bottom plate of the PC box girder segment 3.

In the embodiment, shear keys 5 are arranged at two ends of a UHPC bottom plate 21 of a pier top beam section UHPC-NC combined box beam section 2, and the structure of the shear keys is a tongue-and-groove/tenon; the tenon is nested in the mortise to realize the joggling of two adjacent sections. In order to improve the connection firmness of two adjacent UHPC bottom plates, a plurality of tenon-and-mortise structures are arranged on the end surfaces of the two adjacent UHPC bottom plates. The shear key is a main component for transferring shear force between the segments, and the shear-resisting bearing capacity between the segments can be increased by adopting a mortise and tenon structure. When the UHPC bottom plate of the embodiment is used for splicing, an adhesive is smeared among the segments to form an adhesive joint.

The construction method of the continuous box girder bridge of the prestressed UHPC-NC mixed system comprises the following steps:

s1, constructing a pile foundation and a pier;

s2, prefabricating a UHPC bottom plate of the UHPC-NC combined box girder segment in a girder factory;

s3, installing a UHPC bottom plate of a pier top UHPC-NC combined structure on the pier, pouring an NC box girder above the UHPC bottom plate to form a UHPC-NC combined box girder segment, and temporarily solidifying the 0# segment and tensioning a prestressed steel bundle;

s4, installing a 1# section UHPC prefabricated bottom plate, coating epoxy resin glue on the splicing surface and performing temporary prestress tensioning on the bottom plate to ensure the full bonding of the epoxy resin glue of the prefabricated structure; then pouring the NC box girder of the No. 1 segment, and simultaneously adjusting the temporary prestress of the bottom plate to avoid overlarge local stress of the UHPC prefabricated bottom plate; finally, tensioning corresponding main beam prestress steel beams, and removing the temporary prestress of the bottom plate;

s5, symmetrically constructing a UHPC-NC box girder structure on two sides of the constructed segment according to the sequence of assembling a UHPC bottom plate, tensioning temporary prestress → pouring an NC box girder by a cantilever, adjusting the temporary prestress → tensioning a main girder prestressed steel beam and dismantling the temporary prestress;

s6, after the construction of the UHPC-NC combined segment is completed, the PC box girder segment is cast by a cantilever and the side span PC box girder segment is cast by a full framing, and the tensioning of corresponding prestressed bundles is completed until the side span and the middle span are folded; before mid-span closure, removing the temporary consolidation of the 0# segment;

and S7, completing the auxiliary engineering of the continuous box girder bridge and the bridge deck pavement.

Example 2

Please refer to fig. 13, which is a schematic structural diagram of an embodiment 2 of the hybrid UHPC-NC continuous box girder bridge according to the present invention. The prestressed UHPC-NC mixed system continuous box girder bridge is a continuous rigid frame bridge, the span is arranged to be 60m +110m +60m, the bridge comprises a bridge pier 1, UHPC-NC combined box girder segments 2, PC box girder segments 3 and a prestressed system (not numbered), the UHPC-NC combined box girder segments 2 are arranged on pier top beam segments, the rest segments adopt the PC box girder segments 3, and the prestressed system adopts an external prestressed and internal prestressed mixed stress system in the longitudinal direction of a box girder. In this example, the bending tensile strength of UHPC was 20MPa or more and the compressive strength was 120MPa or more.

Different from embodiment 1, the continuous box girder bridge of this embodiment is a continuous rigid frame bridge, the pier top of which is consolidated with the 0# segment, and other structures are the same as those of embodiment 1, and are not described herein again.

The construction method of the continuous box girder bridge of the prestressed UHPC-NC mixed system comprises the following steps:

s1, constructing a pile foundation and a pier;

s2, prefabricating a UHPC bottom plate of the UHPC-NC combined box girder segment in a girder factory;

s3, installing a UHPC bottom plate of a pier top UHPC-NC combined structure on the pier, pouring an NC box girder above the UHPC bottom plate to form a UHPC-NC combined box girder segment, and consolidating the 0# segment and tensioning a prestressed steel bundle;

s4, installing a 1# section UHPC prefabricated bottom plate, coating epoxy resin glue on the splicing surface and performing temporary prestress tensioning on the bottom plate to ensure the full bonding of the epoxy resin glue of the prefabricated structure; then pouring the NC box girder of the No. 1 segment, and simultaneously adjusting the temporary prestress of the bottom plate to avoid overlarge local stress of the UHPC prefabricated bottom plate; finally, tensioning corresponding main beam prestress steel beams, and removing the temporary prestress of the bottom plate;

s5, symmetrically constructing a UHPC-NC box girder structure on two sides of the constructed segment according to the sequence of assembling the UHPC bottom plate, tensioning the temporary prestress → pouring the NC box girder by the cantilever, adjusting the temporary prestress → tensioning the prestressed steel beam of the main girder and dismantling the temporary prestress;

s6, after the UHPC-NC combined segment construction is completed, cantilever casting of the PC box girder segment and full framing casting of the side span PC box girder segment are performed, and tensioning of corresponding prestressed bundles is completed until the side span and the middle span are folded;

and S7, completing the auxiliary engineering of the continuous box girder bridge and the bridge deck pavement.

The utility model discloses a continuous box girder bridge of prestressing force UHPC-NC mixed system can be used to for rebuilding the bridge type. Before the bridge is rebuilt, the bearing capacity of the original pier foundation is evaluated, and the upper structure of the old bridge is dismantled after the requirement is met. By adopting the UHPC-NC combined box girder segment and PC box girder segment mixed system continuous box girder bridge, the overall rigidity of the new bridge is improved, excessive downwarping of the main span after operation for years is avoided, the original pier can be reused, and the reconstruction scheme cost is greatly reduced. Therefore, the utility model discloses a continuous box girder bridge of prestressing force UHPC-NC mixed system is an extremely competitive rebuild bridge type scheme.

Compared with the prior art, the utility model provides a continuous box girder bridge of prestressing force UHPC-NC mixed system, beneficial effect lies in:

1. the utility model provides a continuous box girder bridge of prestressing force UHPC-NC mixed system adopts UHPC-NC integrated configuration at mound top region festival section, and all the other festival sections adopt PC box girder structure, based on the characteristics that UHPC light, high strength and low shrink creep, can reduce box girder plate thickness by a wide margin, reduce superstructure weight, improve the long-term rigidity of structure, reduce bridge structures creep and shrink by a wide margin, can follow the excessive downwarping of root cause's bridge owner stride.

2. The utility model provides a continuous box girder bridge of prestressing force UHPC-NC mixed system, the prefabricated construction all adopts the UHPC material, can realize the lightweight of prefabricated construction, makes the prefabrication of superstructure, transportation, installation easier, and this accords with the theory of constructing the bridge fast; meanwhile, the pier top area section adopts a method combining prefabrication and cast-in-place, so that the requirement of hoisting equipment can be reduced, and the construction risk is reduced; and other segments adopt cast-in-place PC box girder structures and adopt a cantilever pouring mode, so that the technical requirements and the equipment requirements are lower.

3. The utility model provides a continuous box girder bridge of prestressing force UHPC-NC mixed system, the dead weight is lighter, to the part because of the main span excessively downwarping the PC continuous beam bridge that needs the rebuild urgently, the construction unit can adopt this mixed system bridge type after carrying out reasonable aassessment to existing abutment, this not only improves the bulk rigidity of new bridge, the main span excessively downwarping appears after avoiding operating several years, can also reuse original abutment, reduce the reconstruction scheme cost by a wide margin. Therefore, the utility model discloses a continuous box girder bridge of prestressing force UHPC-NC mixed system is an extremely competitive rebuild bridge type scheme.

4. Compared with the prior art (Chinese patent application CN 114197321A), the utility model discloses a to need to demolish the continuous system bridge of rebuilding because of excessive downwarping and roof beam body fracture, under the prerequisite that its existing pier of aassessment has sufficient bearing capacity, the novel mixed system continuous beam bridge that provides. The bridge type comprises two types of box girder segments which are respectively a PC box girder segment and a UHPC-NC box girder segment, and does not adopt a full UHPC box girder segment, on one hand, the reconstructed bridge type does not have the requirement of lifting span, and compared with the traditional PC box girder bridge with the same span, the bridge type can improve the rigidity of a girder body and reduce the weight of an upper structure of the bridge because the UHPC-NC box girder segment is introduced, the bridge type can not only meet the requirement of reconstructing the bridge type to a certain extent, but also has competitive economy; on the other hand, the prefabrication, transportation and hoisting of the full UHPC box girder segment have extremely high requirements on manufacturing process, road transportation conditions, hoisting equipment and the like, and the requirements on high technology, good road conditions and equipment are difficult to meet in most areas needing to rebuild bridges. Therefore, for most areas, both from an economic perspective and from a realistic standpoint, it is not desirable to employ all UHPC box girder segments and their prefabricated, assembled construction methods to reconstruct the bridge.

The embodiments of the present invention have been described in detail, but the present invention is not limited to the described embodiments. Various changes, modifications, substitutions and alterations to these embodiments will be apparent to those skilled in the art without departing from the principles and spirit of the invention.

Claims (10)

1. The continuous box girder bridge with the prestressed UHPC-NC mixed system is characterized by comprising UHPC-NC combined box girder segments, PC box girder segments and a prestressed system which adopts whole-body external prestress or partial external prestress in the longitudinal direction, wherein the UHPC-NC combined box girder segments comprise UHPC bottom plates with prefabricated structures and NC box girders with cast-in-place structures supported on the UHPC bottom plates, the UHPC-NC combined box girder segments are positioned in the top areas of support piers and have the length of 1/4-1/3 of the main span length, and the PC box girder segments are positioned in the areas except the UHPC-NC combined box girder segments.

2. The prestressed UHPC-NC hybrid system continuous box girder bridge according to claim 1, wherein the NC box girder comprises a first top plate, a first web plate, a first bottom plate and a first diaphragm plate, wherein the first top plate and the first web plate of the NC box girder are both flat plate members, the first bottom plate of the NC box girder is a short rib plate member, and the first diaphragm plate of the NC box girder is composed of at least one of a first top plate stiffener, a first web stiffener and a first bottom plate stiffener;

the UHPC bottom plate is a short rib plate component, the NC box girder is arranged on the UHPC bottom plate, the UHPC bottom plate and the first bottom plate of the NC box girder are connected into a whole through the UHPC bottom plate reserved steel bars, and the reserved steel bars are arranged in parallel along the bridge direction and the transverse bridge direction.

3. The prestressed UHPC-NC hybrid system continuous box girder bridge according to claim 2, wherein the UHPC floor is a low rib plate member consisting of a flat plate and longitudinal ribs, wherein the thickness of the flat plate is 0.12 to 1.50m, the height of the longitudinal ribs is 0.10 to 0.50m, the width of the upper edges of the longitudinal ribs is 0.10 to 0.30m, the width of the lower edges of the longitudinal ribs is 0.12 to 0.32m, and the center-to-center distance between adjacent longitudinal ribs is 0.30 to 1.50m;

the first top plate, the first web plate, the first bottom plate and the first diaphragm plate of the NC box girder are all thick members, wherein the thickness of the first top plate is 0.25-1.50 m, the thickness of the first web plate is 0.40-2.50 m, the thickness of the first bottom plate is 0.28-2.50 m, and the thickness of the first diaphragm plate is 1.50-4.00 m.

4. The prestressed UHPC-NC hybrid system continuous box girder bridge according to claim 1, wherein the PC box girder segment comprises a second top plate having a thickness of 0.25m to 1.50m, a second bottom plate having a thickness of 0.40m to 2.50m, a second web plate having a thickness of 1.50m to 4.00m, and a second bottom plate having a thickness of 0.50m to 4.00m.

5. The prestressed UHPC-NC hybrid system continuous box girder bridge of claim 1, wherein a rigidity transition section is arranged between the UHPC-NC combined box girder segment and the PC box girder segment, the rigidity transition section is an UHPC-NC combined structure and comprises a transition section NC box girder and a transition section UHPC bottom plate, the transition section NC box girder comprises a third top plate, a third web plate and a third bottom plate, the third top plate and the third web plate of the transition section NC box girder are both flat plate members, and the third bottom plate of the transition section NC box girder is a short rib plate member; a third top plate, a third web plate and a third bottom plate of the NC box girder at the transition section are all thick components, wherein the thickness of the third top plate is 0.25-1.50 m, the thickness of the third web plate is 0.40-2.50 m, and the thickness of the third bottom plate is 0.28-2.50 m;

the transition section UHPC bottom plate is a short rib plate member consisting of a flat plate and longitudinal ribs, wherein the thickness of the flat plate is 0.12-1.50 m, the height of the longitudinal ribs is 0.10-0.50 m, the width of the upper edges of the longitudinal ribs is 0.10-0.30 m, the width of the lower edges of the longitudinal ribs is 0.12-0.32 m, and the center distance between adjacent longitudinal ribs is 0.30-1.50 m.

6. The continuous box girder bridge of the prestressed UHPC-NC hybrid system as claimed in claim 5, wherein the thicknesses of the two ends of the third top plate and the third web plate of the rigidity transition section are respectively and correspondingly the same as the structural thicknesses of the adjacent UHPC-NC combined box girder segment and the adjacent PC box girder segment; the total thickness of two ends of the third bottom plate of the rigidity transition section is respectively the same as the total thickness of the bottom plate of the adjacent UHPC-NC combined box girder segment and the thickness of the bottom plate of the PC box girder segment, and the thickness of the UHPC bottom plate of the rigidity transition section is gradually reduced from the UHPC-NC combined box girder segment to the PC box girder segment.

7. The continuous box girder bridge of a prestressed UHPC-NC hybrid system as claimed in claim 1, wherein the prestressed system comprises an in-vivo prestressed structure and an in-vitro prestressed structure which are arranged on the UHPC-NC combined box girder segment and the PC box girder segment, and the anchoring and turning of the in-vivo prestressed structure and the in-vitro prestressed structure are both positioned at the corresponding diaphragm plate.

8. The continuous box girder bridge of pre-stressed UHPC-NC mixed system according to claim 1, characterized in that the continuous box girder bridge of pre-stressed UHPC-NC mixed system is of continuous rigid frame bridge type or continuous beam bridge type.

9. The pre-stressed UHPC-NC hybrid system continuous box girder bridge according to any one of claims 1 to 8, wherein the pre-stressed UHPC-NC hybrid system continuous box girder bridge is a rebuilt bridge.

10. The prestressed UHPC-NC hybrid system continuous box girder bridge according to any one of claims 1-8, characterized in that the span of the prestressed UHPC-NC hybrid system continuous box girder bridge is arranged to be 60m +110m +60m.

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