CN115287996A - Pier top UHPC-NC combined structure UHPC continuous box girder bridge and construction method thereof - Google Patents

Abstract

The invention provides a pier top UHPC-NC combined structure UHPC continuous box girder bridge, which comprises UHPC-NC combined box girder segments, UHPC box girder segments and a prestress system adopting whole-body prestress or partial-body 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 pier top areas of supports, the lengths of the UHPC-NC combined box girder segments are 4-12 meters, and the UHPC box girder segments are positioned in the areas except the UHPC-NC combined box girder segments. According to the UHPC continuous box girder bridge with the pier top UHPC-NC combined structure, the UHPC-NC combined structure is adopted on the pier top, and the UHPC box girder structure is adopted in the rest area, so that the structure is simple, the self weight is light, the economy is good, the main span downwarping and the girder body cracking can be effectively restrained, meanwhile, the assembly construction is facilitated, and the spanning capacity of the concrete girder bridge is increased.

Description

Pier top UHPC-NC combined structure UHPC continuous box girder bridge and construction method thereof

Technical Field

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

Background

The prestressed concrete continuous box girder bridge has the advantages of good stress, simple and convenient construction, good economy and the like, and is widely applied to the field of bridges. However, in the service process, because the tensile strength of common concrete (NC) is extremely low, and the repeated action and overload action of vehicle load are added, the traditional prestressed concrete box girder bridge is easy to crack, and the structural durability is reduced; in addition, under the action of negative bending moment, the top compressive stress of the continuous pier top beam section is small, the bottom compressive stress of the continuous pier top beam section is large, and the shrinkage and creep of common concrete (NC) are large, so that the problem of main span downwarping of the bridge inevitably occurs in the service process. Therefore, the conventional prestressed concrete girder bridge spanning capability is difficult to be further improved by the material properties of the NC itself.

Ultra-high performance concrete (UHPC) has the advantages of high strength, high ductility, high durability, low creep (the creep coefficient of the UHPC is about 15 percent of NC), and the like. Based on the excellent mechanical property of the UHPC, the size of the UHPC plate can be greatly reduced, so that the self weight of the structure is remarkably reduced, the structure spanning capability is improved, and the UHPC plate has great application potential in a large-span bridge. Therefore, the UHPC material is applied to a large-span bridge which urgently needs to reduce the self-weight of the structure, not only can fully exert the excellent performance of the UHPC material, but also has good economy, and is an important research direction for research and application of UHPC bridges.

In the prior art, a bridge system adopting a fully prestressed UHPC box girder structure and a bridge system adopting a UHPC-NC structure on a pier top exist, but in actual engineering application, the bridge systems have respective defects and shortcomings.

For a fully prestressed UHPC box girder structure, a thick diaphragm plate structure is required to be arranged at the pier top to resist the local pressure of a support or a pier, so that the volume and the dead weight of the pier top box girder segment are large, the requirement for installing the pier top segment on hoisting equipment is high, and the assembly construction is not facilitated. Meanwhile, the thick pier top UHPC box girder segment cannot fully exert the high-strength mechanical property of the UHPC, and the overall cost is increased to a certain extent. In addition, the dead weight of the pier top beam section is directly borne by the support and the pier, and almost has no influence on the internal force of the main beam. Therefore, the pier-top box girder segment does not need to be entirely made of UHPC material, both from a force-receiving point of view and from an economical point of view.

For a bridge system with a pier top adopting a UHPC-NC structure, a full bridge comprises PC box beam segments, UHPC box beam segments and UHPC-NC combined box beam segments, and the PC box beam segments and more UHPC-NC combined box beam segments not only increase construction steps and reduce construction quality, but also improve the risk of cracking of a structural beam body to a certain extent. Therefore, all the box girder segments except the pier top segment need to adopt UHPC materials and a construction method of prefabrication and assembly, the construction period is shortened, and the risk of cracking of a bridge main body is reduced.

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 UHPC continuous box girder bridge with a pier top UHPC-NC combined structure, wherein the pier top adopts the UHPC-NC combined structure, and the other areas adopt the UHPC box girder structure, so that the UHPC continuous box girder bridge 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 and increase the spanning capability of the concrete beam bridge.

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

a pier top UHPC-NC combined structure UHPC continuous box girder bridge comprises UHPC-NC combined box girder segments, UHPC box girder segments and a prestress system which adopts whole external prestress or partial external prestress in the longitudinal direction, wherein the UHPC-NC combined box girder segments comprise UHPC bottom plates of prefabricated structures and NC box girders of cast-in-place structures supported on the UHPC bottom plates, the UHPC-NC combined box girder segments are positioned in a support pier top area and have the length of 4-12 meters, and the UHPC box girder segments are positioned in areas except the UHPC-NC combined box girder segments;

the pier top UHPC-NC combined structure UHPC continuous box girder bridge is obtained by adopting the following construction method:

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;

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, mounting 0 on the bridge pier ^# A segmented UHPC bottom plate, an NC box girder is poured above the UHPC bottom plate to form a pier top UHPC-NC combined box girder segment, and the number of the pier top UHPC-NC combined box girder segments is 0 ^# Tensioning the prestressed steel bundles of 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;

s4, symmetrically splicing and prefabricating the UHPC box girder segments on two sides of the constructed segment according to the sequence of cantilever splicing and prestressed steel bundle tensioning, and completing the corresponding prestressed steel bundle tensioning;

step S5, if the continuous bridge is in a continuous bridge type, removing 0 percent before mid-span closure ^# Temporary consolidation of the segments;

and S6, completing the auxiliary engineering of the continuous box girder bridge and the bridge deck pavement.

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.

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 0.30m; 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, tenon and/or mortise shear key structures are arranged at two ends of the pier top UHPC-NC combined box girder section; the end surfaces of the UHPC box girder segments are respectively provided with a tenon and mortise shear key structure, and two adjacent segments are joggled through the tenon and the mortise.

Furthermore, a transition section is arranged between the UHPC-NC combined box girder segment and the UHPC box girder segment, the main material of the transition section is UHPC, and the thicknesses of top plates and web plates at two ends of the transition section are respectively and correspondingly the same as the structural thicknesses of the adjacent UHPC-NC combined box girder segment and UHPC box girder segment; the thickness of the bottom plates at the two ends of the transition section is respectively the same as the total thickness of the bottom plates in the UHPC-NC combined box girder segment and the thickness of the bottom plates of the UHPC 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 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 pier top UHPC-NC combined structure UHPC continuous box girder bridge, which comprises the following steps:

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;

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, mounting 0 on the bridge pier ^# A segmented UHPC bottom plate, an NC box girder is poured above the UHPC bottom plate to form a pier top UHPC-NC combined box girder segment with the length of 4-12m, and the segment number is 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 bridge is a bridge type, the pair is 0 ^# Temporarily solidifying the segments;

s4, symmetrically splicing UHPC prefabricated box girder segments on two sides of the constructed segment according to the sequence of cantilever splicing and prestressed steel bundle tensioning, and completing the corresponding prestressed steel bundle tensioning;

step S5, if the continuous bridge is in a continuous bridge type, removing 0 percent before mid-span closure ^# Temporary consolidation of the segments;

and S6, completing the auxiliary engineering of the continuous box girder bridge and the bridge deck pavement.

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

1. the pier top UHPC-NC combined structure UHPC continuous box girder bridge provided by the invention adopts the UHPC-NC combined structure on the pier top, and the other girder sections adopt the UHPC box girder structures. Based on the excellent mechanical property of the UHPC, the UHPC continuous box girder bridge with the pier top UHPC-NC combined structure can greatly reduce the thickness of plates, reduce the weight of an upper structure, improve the load resisting efficiency of the structure, increase the span diameter of a prestressed concrete girder bridge and improve the durability of the structure; in addition, the weight of the upper structure is greatly reduced, the engineering quantity of the lower structure can be reduced, and the construction cost of the lower structure can be reduced especially at a bridge position with poor geological condition; meanwhile, the NC material is adopted at the position with larger size of the pier top structure, so that the comprehensive cost of bridge construction can be reduced, and the method has good economy.

2. According to the pier top UHPC-NC combined structure UHPC continuous box girder bridge, the prefabricated structures are all made of UHPC materials, so that the light weight of the prefabricated structures can be realized, the prefabrication, transportation and installation of the upper structures are easier, and the concept of quickly constructing the bridge is met; 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; the segments except the pier tops are all prefabricated UHPC box girder structures, and the construction efficiency is greatly improved by adopting a cantilever assembling mode.

3. According to the UHPC continuous box girder bridge with the pier top UHPC-NC combined structure, the bending tensile strength of the UHPC material adopted by the prefabricated structure can reach more than 20MPa, so that the cracking risk of a large-span box girder bridge can be reduced; meanwhile, the shrinkage of the UHPC prefabricated structure (the UHPC bottom plate and the UHPC box girder section of the pier top UHPC-NC combined structure) after high-temperature steam curing can be ignored, the creep is only 20 percent of that of common concrete, and the excessive downwarping of the main span in long-term operation can be effectively restrained.

Drawings

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

FIG. 1 is a schematic structural diagram of an embodiment 1 of a UHPC continuous box girder bridge with a pier top UHPC-NC combined structure;

FIG. 2 is a schematic structural view of a prestressed tendon of a UHPC continuous box girder bridge with a pier top UHPC-NC combined structure;

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

FIG. 4 is a schematic structural view of a UHPC box girder segment in a UHPC continuous box girder bridge with a pier top UHPC-NC combined structure 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 UHPC continuous box girder bridge with the pier top UHPC-NC combined structure of the invention;

FIG. 7 is a schematic structural diagram of a pier top UHPC-NC box girder segment, a UHPC box girder segment and a transition section in the invention;

FIG. 8 isbase:Sub>A schematic cross-sectional view taken along line A-A of FIG. 1;

FIG. 9 is a schematic cross-sectional view taken at B-B in FIG. 1;

FIG. 10 is an enlarged view of portion A of FIG. 9;

FIG. 11 is a schematic view of the cross-sectional view C-C of FIG. 10;

FIG. 12 is an enlarged view of portion B of FIG. 9;

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

FIG. 14 is an enlarged view of portion C of FIG. 9;

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

fig. 16 is a schematic structural diagram of an embodiment 2 of a pier top UHPC-NC combined structure UHPC continuous box girder bridge.

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 15, the pier top UHPC-NC combined structure UHPC continuous box girder bridge of the present embodiment is a continuous girder bridge type, the span is arranged to be 60m +110m +60m, and the pier top UHPC-NC combined structure 2, the UHPC box girder segment 3, and the prestress system 4, the UHPC-NC combined structure 2 are disposed in the pier top area, the length of the pier top UHPC-NC combined structure is 4-12m, the UHPC box girder segment 3 is disposed in an area other than the UHPC-NC combined structure, and the prestress system 4 employs an external prestress and internal prestress mixed stress system in the longitudinal direction of the box girder. In this example, the tensile strength in bending of UHPC was 20MPa or more, and the compressive strength was 120MPa or more.

The UHPC-NC combined structure 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 is a short rib plate member, and the first diaphragm plate 224 of the NC box girder is composed of at least one mode 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 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 plate 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 0.25 m-1.50 m, the thickness of the first web plate 222 is 0.40 m-2.50 m, the thickness of the first bottom plate 223 is 0.28 m-2.50 m, and the thickness of the first diaphragm plate 224 is 1.50 m-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 34, and the second top plate 31, the second web 33, the second bottom plate 32 and the second diaphragm 34 are all thin members, and an orthotropic deck system is formed between the second top plate 31 and the second diaphragm 34.

Wherein, when the second top plate 31 is a flat plate member, the thickness of the second top plate 31 is 0.12 m-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 1.50m. 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 1.50m.

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 binding tooth block 43 is embedded and fixed between the second diaphragm plates 34 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 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, in order to improve the structural stability, a transition section 6 is provided between the UHPC-NC combined box girder segment 2 and the UHPC box girder segment 3. Wherein, the transition section 6 is made of UHPC material, and the thicknesses of the top plate and the web plate at the two ends of the transition section are respectively corresponding to the same structural thicknesses of the adjacent UHPC-NC combined box girder segment and the UHPC box girder segment; the thickness of the bottom plate of one end of the transition section 6, close to the pier top 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 of one end of the transition section 6, close to the UHPC box girder segment 4, is the same as the thickness of the bottom plate of the UHPC box girder segment 4.

In the embodiment, shear keys are arranged at two ends of the pier top HPC-NC combined box girder segment 2, and the structure of the shear keys is a mortise 52; the two ends of the UHPC box girder segment 3 are also provided with shear keys, the structure of the shear keys is a tenon 51, one side of the interface of the two adjacent segments is the tenon 51, the other side of the interface of the two adjacent segments is a mortise 52, and the tenon 51 is nested in the mortise 52 to realize the joggling of the two adjacent segments. The mortise and tenon structure can also be used for arranging mortises at two ends of the HPC-NC combined box girder segment 2 and correspondingly arranging tenons at two ends of the UHPC box girder segment 3. 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 sections. The shear key is a main component for transferring shear force among the segments, and the shear-resistant bearing capacity among the segments can be increased by adopting a mortise and tenon joint 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 pier top UHPC-NC combined structure UHPC continuous box girder bridge comprises the following steps:

s1, constructing a pile foundation and a pier;

s2, prefabricating a UHPC bottom plate of the UHPC box girder segment and 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, symmetrically splicing UHPC prefabricated box girder segments on two sides of the constructed segment according to the sequence of cantilever splicing and prestressed steel bundle tensioning, and completing the corresponding prestressed steel bundle tensioning;

s5, forming a whole by tensioning partial prestressed steel bundles for the side span UHPC box girder segment and the main span part UHPC box girder segment, 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 mid-span UHPC box girder segment of the continuous box girder bridge, performing mid-span closure and prestressed steel beam tensioning in the full-bridge span, and removing the temporary consolidation of the 0# segment before mid-span closure;

and S6, completing the auxiliary engineering of the continuous box girder bridge and the bridge deck pavement.

Example 2

Please refer to fig. 16, which is a schematic structural diagram of an embodiment 2 of the UHPC continuous box girder bridge with a pier top UHPC-NC combined structure according to the present invention. The pier top UHPC-NC combined structure UHPC continuous box girder bridge is a continuous rigid frame bridge, the span is arranged to be 60m +110m +60m, the bridge comprises a pier 1, a UHPC-NC combined box girder segment 2, a UHPC box girder segment 3 and a prestress system (not numbered), and the UHPC-NC combined box girder segment 2 is arranged on the pier top 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 tensile strength in bending of UHPC was 20MPa or more, and the compressive strength was 120MPa or more.

Different from embodiment 1, the continuous box girder bridge of the present embodiment is a continuous rigid frame bridge, the pier of the continuous rigid frame bridge is fixedly connected with the segment 0, and other structures are the same as those of embodiment 1 and are not described herein.

The construction method of the novel UHPC continuous box girder bridge with the pier top UHPC-NC combined structure comprises the following steps:

s1, constructing a pile foundation and a pier;

s2, prefabricating UHPC bottom plates of the UHPC box girder segment and the pier top 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 pairing 0 ^# Solidifying the segments and tensioning the prestressed steel bundles;

s4, symmetrically assembling UHPC precast box girder segments on two sides of the constructed segment according to the sequence of assembling the cantilever and tensioning the prestressed steel bundles, and completing tensioning of the corresponding prestressed steel bundles;

s5, respectively forming a whole by tensioning partial prestressed steel bundles on 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;

and S6, completing the auxiliary engineering of the continuous box girder bridge and the bridge deck pavement.

The embodiments of the present invention have been described in detail, but the present invention is not limited to the described embodiments. It will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, and these embodiments are therefore considered to be within the scope of the invention.

Claims (9)

1. A pier top UHPC-NC combined structure UHPC continuous box girder bridge is characterized by comprising UHPC-NC combined box girder segments, UHPC box girder segments and a prestress system adopting whole or partial external prestress in the longitudinal direction, wherein each UHPC-NC combined box girder segment comprises a UHPC bottom plate of a prefabricated structure and a cast-in-place structure NC box girder supported on the UHPC bottom plate, each UHPC-NC combined box girder segment is positioned in a support pier top area and has the length of 4-12m, and each UHPC box girder segment is positioned in an area except the UHPC-NC combined box girder segment;

the pier top UHPC-NC combined structure UHPC continuous box girder bridge is obtained by adopting the following construction method:

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;

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, mounting 0 on the bridge pier ^# A segmented UHPC bottom plate is poured, an NC box girder is poured above the UHPC bottom plate to form a pier top UHPC-NC combined box girder segment, and the pair number 0 is ^# 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;

s4, symmetrically assembling prefabricated UHPC box girder segments on two sides of the constructed segment according to the sequence of cantilever assembling and prestressed steel beam tensioning, and completing corresponding prestressed steel beam tensioning;

step S5, if the continuous beam bridge is in a continuous beam bridge type, removing 0 percent before mid-span closure ^# Temporary consolidation of the segments;

and S6, completing the auxiliary engineering of the continuous box girder bridge and the bridge deck pavement.

2. The pier top UHPC-NC combined structure UHPC continuous box girder bridge according to the claim 1, characterized in that 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 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.

3. The pier top UHPC-NC combined structure UHPC continuous box girder bridge as claimed in claim 2, wherein the UHPC bottom plate is a low 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.

4. The pier top UHPC-NC combined structure UHPC continuous box girder bridge according to claim 1, wherein the UHPC box girder segment comprises a second top plate, a second bottom plate, a second web plate and a second diaphragm plate, the second top plate, the second web plate, the second bottom plate and the second diaphragm plate are all thin members, and an orthogonal opposite deck system is formed between the second top plate and the second diaphragm plate.

5. The pier top UHPC-NC combined structure UHPC continuous box girder bridge according to claim 4, characterized in that when the second top plate is a flat plate member, the thickness of the second top plate is 0.12 m-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.

6. The pier top UHPC-NC combined structure UHPC continuous box girder bridge as claimed in claim 1, characterized in that tenon and/or mortise shear key structures are arranged at two ends of the pier top UHPC-NC combined box girder segment; the end faces of the UHPC box girder sections are respectively provided with a tenon and mortise shear key structure, and two adjacent sections are joggled through the tenons and the mortises.

7. The pier top UHPC-NC combined structure UHPC continuous box girder bridge as claimed in claim 1, wherein a transition section is arranged between the UHPC-NC combined box girder segments and the UHPC box girder segments, the main material of the transition section is UHPC, and the thicknesses of top plates and web plates at two ends of the transition section are respectively and correspondingly the same as the thicknesses of the structures of the adjacent UHPC-NC combined box girder segments and the UHPC box girder segments; the thickness of the bottom plates at the two ends of the transition section is respectively the same as the total thickness of the bottom plates in the UHPC-NC combined box girder segment and the thickness of the bottom plates of the UHPC box girder segment.

8. The pier top UHPC-NC combined structure UHPC continuous box girder bridge according to claim 1, characterized in that 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 turning of the in-vivo prestress structure and the in-vitro prestress structure are positioned at the corresponding diaphragm plates.

9. A construction method of a UHPC continuous box girder bridge with a pier top UHPC-NC combined structure is characterized by comprising the following steps:

s1, constructing a pile foundation and a pier, wherein if the bridge is a continuous rigid frame bridge type, the pier adopts a thin-wall flexible pier;

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, mounting 0 on the bridge pier ^# A segmented UHPC bottom plate, an NC box girder is poured above the UHPC bottom plate to form a pier top UHPC-NC combined box girder segment with the length of 4-12m, and the segment number is 0 ^# Tensioning the prestressed steel bundles on the segments; if the bridge is a continuous rigid frame bridge type, pier beam consolidation is carried out; if the continuous bridge is a bridge type, the pair is 0 ^# Temporarily solidifying the segments;

s4, symmetrically assembling UHPC precast box girder segments on two sides of the constructed segment according to the sequence of assembling the cantilever and tensioning the prestressed steel bundles, and completing tensioning of the corresponding prestressed steel bundles;

step S5, if the continuous bridge is in a continuous bridge type, removing 0 percent before mid-span closure ^# Temporary consolidation of the segments;

and S6, completing the auxiliary engineering of the continuous box girder bridge and the bridge deck pavement.

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