CN114197321A

CN114197321A - Prestressed UHPC-NC combined continuous box girder bridge and construction method thereof

Info

Publication number: CN114197321A
Application number: CN202210012917.8A
Authority: CN
Inventors: 赵华; 罗穗; 谭承君; 邵旭东; 孙韬; 涂磊; 张阳
Original assignee: Hunan University
Current assignee: Hunan University
Priority date: 2022-01-06
Filing date: 2022-01-06
Publication date: 2022-03-18
Anticipated expiration: 2042-01-06
Also published as: CN114197321B

Abstract

The invention provides a prestressed UHPC-NC combined continuous box girder bridge, which comprises UHPC-NC combined box girder segments, UHPC box girder segments and a prestressed system adopting whole external prestress or partial external prestress in the longitudinal direction, wherein the UHPC-NC combined box girder segments are positioned in the region from the central line of the top of a support pier to a main span 1/3-1/4; the UHPC box girder segment is located in a main span middle area, and the total length of the UHPC box girder segment is 1/4-1/3 of the length of the main span. The prestressed UHPC-NC combined continuous box girder bridge provided by the invention has the advantages of simple structure, light self weight and good economical efficiency, can effectively inhibit main span downwarping and girder body cracking, and is convenient for assembly construction. The invention also provides a construction method of the prestressed UHPC-NC combined continuous box girder bridge.

Description

Prestressed UHPC-NC combined continuous box girder bridge and construction method thereof

Technical Field

The invention relates to the technical field of bridge engineering, in particular to a prestressed UHPC-NC combined continuous box girder bridge and a construction method thereof.

Background

The prestressed concrete continuous beam bridge has the advantages of simple structure, definite stress, good economy and the like, and is widely applied to the field of bridges. However, in the long-term use process, the tensile strength of common concrete (NC) is low, and in addition, the repeated action and overload action of vehicle load easily cause the beam body to crack, and the structural durability is reduced; in addition, the dead weight of the common concrete bridge structure is large, the shrinkage and creep of the concrete are large, the problem of main span downwarping inevitably occurs, and the economic span of the concrete continuous beam is difficult to break through 400 m. Therefore, the further improvement of the spanning capability of the prestressed concrete beam bridge is limited by the material performance of the NC.

Ultra High Performance Concrete (UHPC) is a cement-based material with a compressive strength greater than 120MPa, high tensile strength, high toughness and high durability. Due to the excellent mechanical property, the size of the bridge structure and the weight of the upper structure can be greatly reduced, and the assembly construction is facilitated. In addition, the existing engineering practice shows that UHPC is applied to bridge engineering, can improve the anti-crack safety and the structural bearing capacity of bridges and increase the spanning capacity. Therefore, the UHPC-based prestressed concrete continuous beam bridge is expected to solve the technical problems of the traditional prestressed continuous beam bridge.

In the prior art, a full-prestress UHPC continuous box girder structure is adopted, but the bridge structure is arranged at the pier top 0^#The segment is influenced by the local pressure bearing of the support or the pier, the structural size is large, and a thicker diaphragm plate structure is required to be arranged, so that the volume of the segment near the pier top is about 50-200% of that of a common segment, and the segment has higher requirements on hoisting equipment for mounting the pier top segment and is not beneficial to assembly construction; meanwhile, if the beam sections near the pier tops are all made of UHPC materials, the structural stress level is low, and the advantages of the UHPC materials cannot be fully exerted.

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

Disclosure of Invention

The invention aims to solve the technical problem of providing a prestressed UHPC-NC combined continuous box girder bridge which is simple in structure, light in self weight and good in economical efficiency, can effectively inhibit main span downwarping and girder body cracking, and is convenient for assembly construction.

In order to solve the problems, the technical scheme of the invention is as follows:

a prestressed UHPC-NC combined continuous box girder bridge comprises UHPC-NC combined box girder segments, UHPC box girder segments and a prestressed system which adopts full external prestress or partial external prestress in the longitudinal direction, wherein the UHPC-NC combined box girder segments are positioned in the region from the central line of the top of a support pier to a main span 1/3-1/4; the UHPC box girder segment is located in a main span middle area, and the total length of the UHPC box girder segment is 1/4-1/3 of the length of the main span.

Further, the UHPC-NC combined box girder segment comprises a UHPC bottom plate and an NC box girder supported on the UHPC bottom plate, the NC box girder comprises a first top plate, a first web plate, a first bottom plate and a first diaphragm plate, 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 stiffening rib, a first web plate stiffening rib and a first bottom plate stiffening rib; the UHPC bottom plate is a short rib plate component, and the NC box girder is arranged on the UHPC bottom plate; the UHPC bottom plate is a prefabricated plate, the NC box girder is of a cast-in-place structure, 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.

Further, the UHPC box girder segment comprises a second top plate, a second bottom plate, a second web plate and a second diaphragm plate, wherein the second top plate, the second web plate, the second bottom plate and the second diaphragm plate are all thin members, and an orthotropic bridge deck system is formed between the second top plate and the second diaphragm plate.

Further, when the second top plate is a flat plate member, the thickness of the second top plate is 0.12m to 0.30 m; when the second top plate is a short rib plate member, the panel thickness is 0.08-0.20 m, the height of the longitudinal rib is 0.10-0.30 m, the width of the upper edge of the longitudinal rib is 0.12-0.30 m, the width of the lower edge of the longitudinal rib is 0.10-0.28 m, and the center distance between adjacent longitudinal ribs is 0.30-1.50 m;

the second web plate and the second bottom plate are both flat plate members, wherein the thickness of the second web plate is 0.12-0.60 m, and the thickness of the second bottom plate is 0.12-1.50 m; the thickness of the second transverse partition plate is 0.12-0.30 m, and one transverse partition plate is arranged every 2-8 m along the longitudinal bridge direction; the second diaphragm plate is composed of at least one mode of a second top plate stiffening rib, a second web stiffening rib and a second bottom plate stiffening rib, and the height of the second diaphragm plate is 0.50-1.50 m.

Furthermore, the end surfaces of the UHPC-NC combined box girder segment and the UHPC box girder segment are respectively provided with a shear key, the shear key is of a mortise and tenon structure comprising a tenon and a mortise, and two adjacent segments are joggled through the tenon and the mortise.

The PC box girder segment comprises a third top plate, a third bottom plate, a third web plate and a third diaphragm plate, 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, the thickness of the third diaphragm plate is 1.50-4.00 m, and the thickness of the third bottom plate is 0.50-4.00 m.

Furthermore, a first transition section is arranged between the UHPC-NC combined box girder segment and the PC box girder segment, and the thicknesses of a top plate and a web plate at two ends of the first transition section are respectively correspondingly the same as the structural thicknesses of the adjacent UHPC-NC combined box girder segment and the adjacent PC box girder segment; the bottom plate of the first transition section comprises a UHPC layer and an NC layer, the thickness of the UHPC layer is the same as that of the UHPC bottom plate in the UHPC-NC combined box girder segment, and the thickness of the NC layer is gradually reduced to 0 from the same thickness as that of the first bottom plate in the UHPC-NC combined box girder segment; a second transition section is arranged between the UHPC box girder segment and the PC box girder segment, and the thicknesses of a top plate, a web plate and a bottom plate at two ends of the second transition section are respectively correspondingly the same as the structural thicknesses of the UHPC box girder segment and the PC box girder segment which are adjacent to each other; starting from the PC box girder segment, the thickness change of the plate is gradually thinned to be the same as that of the UHPC box girder plate.

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 UHPC 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.

The invention also provides a construction method of the prestressed UHPC-NC combined continuous box girder bridge, which comprises the following steps:

step S1, constructing a pile foundation and a pier, wherein if the bridge is a continuous rigid frame bridge type, the pier is a thin-wall flexible pier;

step S2, prefabricating a UHPC bottom plate of the UHPC box girder segment and the UHPC-NC combined box girder segment; if the section is a continuous rigid frame bridge type, a pore channel for pier-beam consolidation is reserved on the UHPC bottom plate of the UHPC-NC combined box-beam section;

step S3, installing 0 on the pier^#A segmented UHPC floor and casting over the UHPC floorThe NC box girder forms UHPC-NC combined box girder segment and is paired with 0^#Tensioning the prestressed steel bundles on the segments; if the bridge is a continuous rigid frame bridge type, pier and beam consolidation is carried out; if the continuous beam bridge type is adopted, the pair is 0^#Temporarily solidifying the segments;

step S4, according to the sequence of cantilever casting and prestressed steel beam tensioning, taking the UHPC bottom plate as a bottom die, symmetrically cantilever-casting UHPC-NC box girder segments on two sides of the cast segment, and completing the corresponding prestressed steel beam tensioning;

step S5, if construction conditions and hoisting equipment meet requirements, the side span UHPC box girder segment and the UHPC box girder segment in the main span respectively form a whole through tensioning partial prestressed steel bundles, then the side span UHPC whole box girder segment of the continuous box girder bridge is erected firstly, the side span is folded, and the tensioning of the residual prestressed steel bundles is carried out; then, erecting a main span middle UHPC integral box girder segment of the continuous box girder bridge, folding a middle span and tensioning a prestressed steel beam in a full bridge span;

if the construction conditions and the hoisting equipment do not meet the requirements, constructing the UHPC box girder segment by adopting a conventional prefabrication and assembly construction method;

step S6, if the bridge is a continuous bridge type, removing 0 percent before mid-span closure^#Temporary consolidation of the segments;

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

Compared with the prior art, the prestressed UHPC-NC combined continuous box girder bridge provided by the invention has the beneficial effects that:

the prestressed UHPC-NC combined continuous box girder bridge provided by the invention has the advantages that based on the excellent mechanical property of UHPC, the structural size of the bridge can be greatly reduced, the weight of the upper structure is reduced, the structural load resisting efficiency is improved, the span length of the prestressed concrete beam bridge is increased, and the structural durability is improved.

Secondly, the pre-stressed UHPC-NC combined continuous box girder bridge provided by the invention has the advantages that the pre-fabricated structure is made of UHPC materials, so that the light weight of the pre-fabricated structure can be realized, and the structure is easier to pre-fabricate, assemble and transport; meanwhile, the pier top large section adopts a method of combining prefabrication and cast-in-place, so that the requirement of hoisting equipment can be reduced, and the construction risk is reduced.

Thirdly, the prestress UHPC-NC combined continuous box girder bridge provided by the invention has lighter self weight, can reduce the engineering quantity of a lower structure, and can reduce the construction cost of the lower structure particularly at a bridge position with poorer geological condition; meanwhile, the NC material is adopted at the position with larger size of the pier top structure, so that the material cost and the construction cost can be further reduced, and the method has good economy.

The bending tensile strength of the adopted UHPC can reach more than 20MPa, and the beam section of the pier top area is the UHPC-NC combined box beam section, so that the structural size is large, the stress is low, and the cracking risk of the large-span box beam bridge can be reduced; shrinkage and creep of the UHPC are extremely small and negligible in the later period of high-temperature steam curing, and excessive downwarping of the beam body in long-term operation is effectively avoided.

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 introduced 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 based on these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of an embodiment 1 of a prestressed UHPC-NC combined continuous box girder bridge of the invention;

FIG. 2 is a schematic structural diagram of a prestressed tendon of a prestressed UHPC-NC combined continuous box girder bridge;

FIG. 3 is a schematic structural diagram of a UHPC-NC combined box girder segment in the prestressed UHPC-NC combined continuous box girder bridge according to the invention;

FIG. 4 is a schematic structural view of a UHPC box girder segment in a pre-stressed UHPC-NC combined continuous box girder bridge according to the invention;

FIG. 5 is a schematic view of another angled configuration of the UHPC box beam segment of FIG. 4;

FIG. 6 is a schematic diagram of the UHPC box girder segment prestress arrangement in the prestress UHPC-NC combined continuous box girder bridge according to the invention;

FIG. 7 is a schematic view of a UHPC-NC box girder segment with a PC segment, a first transition section according to the present invention;

FIG. 8 is a schematic view of a UHPC box girder segment with a PC segment, a second transition section according to the present invention;

FIG. 9 is 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 a schematic cross-sectional view at C-C of FIG. 1;

FIG. 12 is an enlarged view of portion A of FIG. 10;

FIG. 13 is a schematic view of the cross-sectional structure D-D of FIG. 12;

FIG. 14 is an enlarged view of portion B of FIG. 10;

FIG. 15 is a schematic view of the cross-sectional structure E-E of FIG. 14;

FIG. 16 is an enlarged view of portion C of FIG. 10;

FIG. 17 is a schematic view of the cross-sectional F-F structure of FIG. 16;

fig. 18 is a schematic structural diagram of a prestressed UHPC-NC combined continuous box girder bridge according to embodiment 2 of the present invention.

Detailed Description

The following description of the present invention is provided to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention and to make the above objects, features and advantages of the present invention more comprehensible.

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 to 17, the prestressed UHPC-NC combined continuous box girder bridge of the present embodiment is a continuous girder bridge type, the span is arranged to be 60m +110m +60m, and includes a pier 1, a UHPC-NC combined box girder segment 2, a UHPC box girder segment 3, a prestressed system 4, and a PC box girder segment 6, the UHPC-NC combined box girder segment 2 is disposed in a length region from a pier top to a main span 1/3-1/4, the UHPC box girder segment 3 is disposed in a length region of about the main span 1/3-1/4, the rest segments are PC box girder segments 6, and the prestressed system 4 employs a mixed stress system of external prestress and internal prestress 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 222, a first bottom plate 223 and a first diaphragm plate 224, the first top plate 221 and the first web 222 of the NC box girder are both flat plate members, the first bottom plate 223 of the NC box girder 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 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 precast slab, the NC box girder 22 is a cast-in-place structure, the UHPC bottom plate 21 and the first bottom plate 223 of the NC box girder 22 are connected into a whole by the reserved reinforcing steel bars of the UHPC bottom plate, and the reserved reinforcing 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 1.50 m. The prefabricated UHPC bottom plate 21 on the pier top can be used as a bottom template of a cast-in-place NC structure by adopting the structural size, and the rigidity and the stability in construction can be ensured.

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 4.00 m. 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 UHPC box girder segment 3 includes a second top plate 31, a second bottom plate 32, a second web 33 and a second diaphragm plate 34, and the second top plate 31, the second web 33, the second bottom plate 32 and the second diaphragm plate 34 are all thin members, and an orthotropic deck system is formed between the second top plate 31 and the second diaphragm plate 34.

Wherein, when the second top plate 31 is a flat plate member, the thickness of the second top plate 31 is 0.12m to 0.30 m; when the second top plate 31 is a short rib plate member, the panel thickness is 0.08m to 0.20m, the longitudinal rib height is 0.10m to 0.30m, the upper edge width of the longitudinal rib is 0.12m to 0.30m, the lower edge width of the longitudinal rib is 0.10m to 0.28m, and the center distance between adjacent longitudinal ribs is 0.30m to 1.50 m. In the present embodiment, the second top plate 31 is a short rib member.

The second web 33 and the second bottom plate 32 are both flat plate members, wherein the thickness of the second web 33 is 0.12-0.60 m, and the thickness of the second bottom plate 32 is 0.12-1.50 m; the thickness of the second diaphragm plate 34 is 0.12 m-0.30 m, and one diaphragm plate is arranged every 2 m-8 m along the longitudinal bridge direction; the second diaphragm 34 is composed of at least one of a second top plate 31 stiffener, a second web 33 stiffener, and a second bottom plate 32 stiffener, and has a height of 0.50m to 1.50 m.

In this embodiment, the pre-stress system 4 includes an external pre-stress tendon 41 and an internal pre-stress tendon 42 provided in the UHPC box girder segment 3. The internal prestressing tendons 42 are embedded in the second top plate 31 and the stiffening ribs of the top plate; the external prestressing tendons 41 pass through the second diaphragm 34 and are anchored by the external tendon tooth blocks 43. The external toe block 43 is fixedly embedded between the second diaphragms 34 and fixedly connected with the inner wall of the second web 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 prestressed beam steering block 44 is embedded and fixed on the side plate of the second diaphragm 34, and one surface of the prestressed beam steering block is fixedly connected with the inner wall of the box girder.

In this embodiment, the PC box girder segment 6 includes a third top plate 61, a third bottom plate 62, a third web 63 and a third diaphragm plate (not shown), and the thickness of the third top plate is 0.25m to 1.50m, the thickness of the third web is 0.40m to 2.50m, the thickness of the third diaphragm plate is 1.50m to 4.00m, and the thickness of the third bottom plate is 0.50m to 4.00 m.

Because the PC box girder segment 6 needs to be jointed with the UHPC-NC combined box girder segment 2 and the UHPC box girder segment 3, in order to keep the stability of the jointing, when the PC box girder segment 6 is jointed with the UHPC-NC combined box girder segment 2 and the UHPC box girder segment 3, a first transition section 7 is arranged between the UHPC-NC combined box girder segment 2 and the PC box girder segment 6, and a second transition section 8 is arranged between the UHPC box girder segment 3 and the PC box girder segment 6.

The thicknesses of top plates and web plates at two ends of the first transition section 7 are respectively and correspondingly the same as the structural thicknesses of adjacent UHPC-NC combined box girder segments and PC box girder segments; and the bottom plate of the first transition section 7 comprises a UHPC layer and an NC layer, the thickness of the UHPC layer is the same as that of the UHPC bottom plate in the UHPC-NC combined box girder segment, and the thickness of the NC layer is gradually reduced to 0 from the same thickness as that of the first bottom plate in the UHPC-NC combined box girder segment, so that the thickness of the bottom plate at one end of the first transition section 7 close to the PC box girder segment 6 is consistent with that of the bottom plate of the PC box girder segment 6.

The thicknesses of the top plate, the web plate and the bottom plate at two ends of the second transition section 8 are respectively and correspondingly the same as the structural thicknesses of the UHPC box girder segment 3 and the PC box girder segment 6 which are adjacent to each other; starting from the PC box girder segment, the thickness change of the plate is gradually thinned to be the same as that of the UHPC box girder plate.

In this embodiment, shear keys 5 are arranged at two ends of the UHPC-NC combined box girder segment 2, the UHPC box girder segment 3 and the PC box girder segment 6, each shear key is of a mortise and tenon structure comprising a tenon 51 and a mortise 52, one side of an interface between two adjacent segments is the tenon 51, the other side of the interface is the mortise 52, and the tenons 51 are nested in the mortises 52 to realize the mortise joint between the two adjacent segments. In order to improve the connection firmness of two adjacent sections, a plurality of mortise and tenon structures are arranged on the end faces of the two adjacent sections. The shear key 5 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 sections of the embodiment are assembled, the adhesive is coated among the sections to form adhesive joints.

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

step S1, constructing a pile foundation and a pier;

step S2, prefabricating UHPC bottom plates of the UHPC box girder segments and the UHPC-NC combined box girder segments in a girder factory;

step S3, installing 0 on the pier^#A UHPC bottom plate of the segments, an NC box girder is poured above the UHPC bottom plate to form UHPC-NC combined box girder segments, and the segments are matched with 0^#Temporarily consolidating the segments and tensioning the prestressed steel bundles;

step S5, according to the sequence of cantilever casting and prestressed steel beam tensioning, erecting a formwork on two sides of the cast segment to symmetrically cast the PC box beam segment in a cantilever manner, and completing the corresponding prestressed steel beam tensioning;

step S6, the side span UHPC box girder segment and the PC box girder segment except the main span pier top form a whole by tensioning partial prestressed steel bundles, then the side span UHPC whole box girder segment of the continuous box girder bridge is erected, the side span is folded, and the tensioning of the residual prestressed steel bundles is carried out; then, erecting a main span middle UHPC box girder segment of the continuous box girder bridge, folding a middle span and tensioning a prestressed steel beam in a full bridge span;

step S7, before mid-span folding, removing 0^#Temporary consolidation of the segments;

and step S8, completing the auxiliary engineering and the bridge deck pavement of the continuous box girder bridge.

Example 2

Please refer to fig. 18, which is a schematic structural diagram of an embodiment 2 of the prestressed UHPC-NC combined continuous box girder bridge according to the present invention. The prestressed UHPC-NC combined continuous box girder bridge is a continuous girder bridge type, the span is arranged to be 60m +110m +60m, the prestressed UHPC-NC combined continuous box girder bridge comprises a pier 1, an UHPC-NC combined box girder segment 2, an UHPC box girder segment 3 and a prestressed system (not numbered), wherein the UHPC-NC combined box girder segment 2 is arranged on the pierTop 0^#And the segments and the rest segments adopt UHPC box girder segments 3, and the prestress system 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.

Different from embodiment 1, the continuous box girder bridge of this embodiment does not include the PC box girder segment, and other structures are the same as those of embodiment 1 and are not described herein again.

Compared with the embodiment 1, the embodiment has the advantages that the UHPC box girder segments are replaced by the PC box girder segments at partial bridge segments, so that the manufacturing cost is saved, and the economical efficiency is higher.

step S1, constructing a pile foundation and a pier;

step S5, respectively forming a whole by tensioning partial prestressed steel bundles for the side span UHPC box girder segment and the UHPC box girder segment in the main span, then erecting the side span UHPC whole box girder segment of the continuous box girder bridge, folding the side span and tensioning the residual prestressed steel bundles; then, erecting a main span middle UHPC integral box girder segment of the continuous box girder bridge, folding a middle span and tensioning a prestressed steel beam in a full bridge span;

step S6, before mid-span folding, removing 0^#Temporary consolidation of the segments;

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 occur to those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. The prestressed UHPC-NC combined continuous box girder bridge is characterized by comprising UHPC-NC combined box girder segments, UHPC box girder segments and a prestressed system which adopts full external prestress or partial external prestress in the longitudinal direction, wherein the UHPC-NC combined box girder segments are positioned in the region from the central line of the tops of supporting piers to a main span 1/3-1/4; the UHPC box girder segment is located in a main span middle area, and the total length of the UHPC box girder segment is 1/4-1/3 of the length of the main span.

2. The prestressed UHPC-NC combined continuous box girder bridge according to claim 1, wherein the UHPC-NC combined box girder segment comprises a UHPC bottom plate and an NC box girder supported on the UHPC bottom plate, the NC box girder comprises a first top plate, a first web, a first bottom plate and a first diaphragm plate, the first top plate and the first web 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, and the NC box girder is arranged on the UHPC bottom plate; the UHPC bottom plate is a prefabricated plate, the NC box girder is of a cast-in-place structure, 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.

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

4. The prestressed UHPC-NC combined continuous box girder bridge according to claim 1, wherein the UHPC box girder segments comprise a second top plate, a second bottom plate, a second web plate and a second diaphragm plate, and the second top plate, the second web plate, the second bottom plate and the second diaphragm plate are all thin members, and an orthotropic deck system is formed between the second top plate and the second diaphragm plate.

5. The prestressed UHPC-NC combined continuous box girder bridge according to claim 4, wherein when the second upper plate is a flat plate member, the thickness of the second upper plate is 0.12 to 0.30 m; when the second top plate is a short rib plate member, the panel thickness is 0.08-0.20 m, the height of the longitudinal rib is 0.10-0.30 m, the width of the upper edge of the longitudinal rib is 0.12-0.30 m, the width of the lower edge of the longitudinal rib is 0.10-0.28 m, and the center distance between adjacent longitudinal ribs is 0.30-1.50 m;

6. The prestressed UHPC-NC combined continuous box girder bridge as claimed in claim 1, wherein the end surfaces of the UHPC-NC combined box girder segment and the UHPC box girder segment are respectively provided with shear keys, the shear keys are in a mortise and tenon structure comprising tenons and mortises, and two adjacent segments are joggled through the tenons and the mortises.

7. The prestressed UHPC-NC combined continuous box girder bridge according to any one of claims 2 to 6, further comprising a PC box girder segment, wherein the PC box girder segment comprises a third top plate, a third bottom plate, a third web plate and a third diaphragm plate, the thickness of the third top plate is 0.25m to 1.50m, the thickness of the third web plate is 0.40m to 2.50m, the thickness of the third diaphragm plate is 1.50m to 4.00m, and the thickness of the third bottom plate is 0.50m to 4.00 m.

8. The prestressed UHPC-NC combined continuous box girder bridge according to claim 7, wherein a first transition section is arranged between the UHPC-NC combined box girder segment and the PC box girder segment, and the thicknesses of a top plate and a web plate at two ends of the first transition section 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 bottom plate of the first transition section comprises a UHPC layer and an NC layer, the thickness of the UHPC layer is the same as that of the UHPC bottom plate in the UHPC-NC combined box girder segment, and the thickness of the NC layer is gradually reduced to 0 from the same thickness as that of the first bottom plate in the UHPC-NC combined box girder segment;

a second transition section is arranged between the UHPC box girder segment and the PC box girder segment, and the thicknesses of a top plate, a web plate and a bottom plate at two ends of the second transition section are respectively correspondingly the same as the structural thicknesses of the UHPC box girder segment and the PC box girder segment which are adjacent to each other; starting from the PC box girder segment, the thickness change of the plate is gradually thinned to be the same as that of the UHPC box girder plate.

9. The prestressed UHPC-NC combined continuous box girder bridge 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 UHPC 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.

10. A construction method of a prestressed UHPC-NC combined continuous box girder bridge is characterized by comprising the following steps:

step S3, installing 0 on the pier^#A UHPC bottom plate of the segments, an NC box girder is poured above the UHPC bottom plate to form UHPC-NC combined box girder segments, and the segments are matched with 0^#Tensioning the prestressed steel bundles on the segments; if the bridge is a continuous rigid frame bridge type, pier and beam consolidation is carried out; if the continuous beam bridge type is adopted, the pair is 0^#Temporarily solidifying the segments;