Prefabricated intermittent steel web-uHPC waffle slab channel beam and construction method

Abstract

The application discloses an assembled intermittent steel web-UHPC waffle bottom plate channel-shaped beam and a construction method. The channel-shaped beam is composed of an intermittent steel web beam, a prefabricated UHPC waffle bottom plate, a reserved hole UHPC, a wet joint, a wet joint steel plate, a transverse prestressed steel bundle and a longitudinal prestressed steel bundle. The intermittent steel web arranged in a wave-shaped plate is adopted in the application, on the basis of ensuring sufficient shearing capacity, the prestress introduction efficiency is improved, and the structure self-weight is obviously reduced. The upper flange of the steel web adopts a hollow semicircular corrugated steel pipe structure containing an I-shaped steel, the position of the neutral axis of the section is raised, and the prestress introduction efficiency is further improved. The prefabricated UHPC waffle bottom plate is introduced, the longitudinal and transverse bending rigidities are enhanced, the bottom plate design thickness is reduced, and the self-weight is greatly reduced. The structure assembly construction can improve the construction quality, shorten the construction time and reduce the influence on the surrounding environment.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering and composite structure design, specifically to a prefabricated intermittent steel web-UHPC waffle bottom plate channel beam and its construction method. Background Technology

[0002] Due to their low structural height, high space utilization, and safe operation, channel beams are widely used in urban rail transit bridges and railway bridges. Currently, concrete channel beams are the most commonly used type of channel beam in practical engineering. However, concrete channel beams have the following drawbacks: heavy self-weight; the web is subjected to combined bending, shear, and torsion, resulting in complex stress, especially at the junction of the web and the bottom plate, where cracks are prone to occur; the large lateral bending moment caused by train loads necessitates a larger design thickness for the bottom plate; and the low neutral axis of the cross-section results in a smaller eccentricity of the prestressed steel strands, leading to lower prestressing efficiency.

[0003] Therefore, some literature replaces the concrete web of the channel beam with a corrugated steel web, proposing a composite channel beam with a corrugated steel web. Compared with the concrete channel beam, this structure can avoid web cracking, reduce self-weight to some extent, and improve prestressing efficiency, but it still has problems such as insufficient improvement in prestressing efficiency, insufficient longitudinal and transverse bending stiffness, heavy self-weight of the concrete base plate, and long construction period. Therefore, there is an urgent need to develop a steel-concrete composite channel beam with sufficiently improved prestressing efficiency, high bending stiffness, light self-weight of the base plate, and fast and convenient construction. Summary of the Invention

[0004] The purpose of this invention is to address the problems of insufficient prestressing efficiency, inadequate longitudinal and transverse bending stiffness, heavy concrete base plate, and long construction period in existing composite channel beams. This invention provides a prefabricated intermittent steel web-UHPC waffle base plate channel beam and its construction method. The problems of existing composite channel beams are solved by improving the steel web structure and flange arrangement, improving the base plate material and structure, and increasing the proportion of prefabricated components.

[0005] The objective of this invention is achieved through the following technical solution: a prefabricated intermittent steel web-UHPC waffle bottom plate channel beam, which consists of an intermittent steel web beam, a prefabricated UHPC waffle bottom plate, a pre-drilled UHPC, a wet joint, a wet joint steel plate, transverse prestressed steel strands, and longitudinal prestressed steel strands.

[0006] The discontinuous steel web beam consists of a discontinuous steel web, an upper flange of the steel web, a bottom plate of the steel web, reinforcements, and a group of threaded studs. The discontinuous steel web is composed of an outer steel web, a middle steel web, and an inner steel web. The outer and inner steel webs are symmetrical about the middle steel web in the transverse direction, while the middle steel web is arranged longitudinally at intervals with the outer and inner steel webs, presenting a longitudinal arrangement similar to a corrugated steel plate. The upper flange of the steel web is composed of an I-beam, a semi-circular corrugated steel pipe, and a top plate of the steel web. The semi-circular corrugated steel pipe contains an I-beam, which is bolted to the top plate of the steel web. The semi-circular corrugated steel pipe is bolted through angle steel to the top plate of the steel web. All discontinuous steel webs are bolted through angle steel to the top and bottom plates of the steel web. The reinforcements are bolted to the outer and bottom plates of the steel web. A group of threaded studs is arranged at intervals on the bottom plate of the steel web.

[0007] The precast UHPC waffle base plate is composed of a panel, longitudinal ribs and transverse ribs; the longitudinal ribs and transverse ribs are arranged orthogonally and located below the panel; the precast UHPC waffle base plate is provided with reserved holes; the precast UHPC waffle base plate is fitted with a group of threaded studs through the reserved holes, positioned and installed on the steel web base plate, and connected to the discontinuous steel web beam by casting the reserved holes UHPC.

[0008] The wet joint is located between two adjacent precast UHPC waffle base plates; the wet joint steel plate is located below the wet joint and is connected to the steel web base plate by bolts; the wet joint steel plate is provided with distributed threaded studs; the adjacent precast UHPC waffle base plates are connected by casting UHPC on the wet joint steel plate.

[0009] The transverse prestressed steel strands are internal prestressed steel strands, installed above the wet joint steel plate;

[0010] The longitudinal prestressed steel strands are external prestressed steel strands, which are installed on the web of the central steel through anchoring and turning devices.

[0011] Furthermore, the width of the intermittent steel web can be 35-45cm, and its thickness is not less than 9mm; the longitudinal spacing of the intermittent steel web can be 0.5-0.8m, and the transverse spacing can be 0.15-0.25m.

[0012] Furthermore, the thickness of the steel web top plate and the steel web bottom plate is not less than 16mm. The width of the steel web top plate needs to take into account the installation of the semi-circular corrugated steel pipe, and the width of the steel web bottom plate needs to be determined according to the arrangement of the reinforcement components and the threaded stud group.

[0013] Furthermore, the dimensions of the I-beam are such that it can be contained within the semi-circular corrugated steel pipe.

[0014] Furthermore, the longitudinal spacing of the threaded stud group is 1-2m, and the internal threaded stud spacing is 5-15cm; the height of the threaded stud is determined according to the thickness of the prefabricated UHPC waffle base plate; the number of threaded studs inside the threaded stud group is determined according to the required shear connection stiffness.

[0015] Furthermore, the length of the prefabricated UHPC waffle base plate can be 8-12m; the thickness of the panel in the prefabricated UHPC waffle base plate can be 6cm, the height of the longitudinal and transverse ribs can be 20cm, and the spacing can be 0.6m; the size of the reserved holes in the prefabricated UHPC waffle base plate is determined according to the arrangement of the threaded stud group.

[0016] Furthermore, the width of the wet joint is 0.3-0.4m, and the thickness is the same as that of the precast UHPC waffle base plate; the width of the wet joint steel plate should not be less than the width of the wet joint.

[0017] Furthermore, both the transverse prestressed steel strands and the longitudinal prestressed steel strands are composed of steel strands.

[0018] A construction method for a channel beam with discontinuous steel web and UHPC waffle bottom plate includes the following steps:

[0019] (1) Set up a simple mobile construction scaffold at the construction site, and fix the threaded studs through the reserved stud holes to the bottom plate of the steel web and the steel plate of the wet joint respectively, forming a group of threaded studs and distributed threaded studs.

[0020] (2) The intermittent steel web is connected to the top plate and bottom plate of the steel web by bolts passing through the angle steel, and the reinforcement is connected to the outer steel web and bottom plate of the steel web by bolts.

[0021] (3) The I-beams are fixed to the top plate of the steel web with bolts, and the semi-circular corrugated steel pipes are connected to the top plate of the steel web by bolts through the angle steel to form a discontinuous steel web beam.

[0022] (4) Hoist the two discontinuous steel web beams and the wet joint steel plate onto the simple mobile construction support, and use bolts to fix the wet joint steel plate between the steel web bottom plates of the two discontinuous steel web beams.

[0023] (5) Lift and install the prefabricated UHPC waffle base plate, so that the threaded studs on the steel web base plate are fitted into the reserved holes of the prefabricated UHPC waffle base plate, and pour the reserved hole UHPC.

[0024] (6) Install and tension transverse prestressed steel strands above the wet joint steel plate, and then cast UHPC on the wet joint steel plate.

[0025] (7) When the strength of UHPC at the wet joint reaches 90% of the design strength, release the transverse prestressed steel strands.

[0026] (8) Longitudinal prestressed steel strands are installed and tensioned on several intermediate steel webs by means of anchoring and turning devices.

[0027] The beneficial effects of this invention are:

[0028] 1. While ensuring sufficient shear resistance, the intermittent steel web, arranged like corrugated steel plates, can not only improve the prestressing efficiency but also significantly reduce its weight and steel consumption. The design of the intermittent steel web can also provide maintenance personnel with access for inspection.

[0029] 2. The flange of the steel web adopts a hollow semi-circular corrugated steel pipe structure containing I-beams, which raises the position of the neutral axis of the section, significantly increases the bending stiffness, and further improves the prestressing introduction efficiency.

[0030] 3. The precast UHPC waffle base plate makes comprehensive use of the ultra-high material properties, the longitudinal and transverse rib structure of the waffle plate and the prestressing effect, which not only significantly improves the longitudinal and transverse bending stiffness and crack resistance, but also reduces the design thickness of the base plate, greatly reducing the self-weight of the structure.

[0031] 4. The wet joint steel plate and reinforcement components enhance the structural stability during construction, which is beneficial for improving the torsional and distortion stiffness of the completed bridge. The wet joint steel plate can also serve as permanent formwork, reducing some of the formwork erection and dismantling work.

[0032] 5. By using prefabricated structural design and components in the factory, the construction quality can be improved, the amount of on-site formwork, steel reinforcement, concrete and other construction work can be greatly reduced, the construction period can be shortened and the impact on the surrounding environment can be reduced. Attached Figure Description

[0033] Figure 1 A three-dimensional view of a prefabricated intermittent steel web-UHPC waffle bottom plate channel beam provided for an embodiment of the present invention;

[0034] Figure 2 A cross-sectional view of a prefabricated intermittent steel web-UHPC waffle bottom plate channel beam provided in an embodiment of the present invention;

[0035] Figure 3 An elevation view of a prefabricated intermittent steel web-UHPC waffle bottom plate channel beam provided for an embodiment of the present invention;

[0036] Figure 4 A perspective view of an intermittent steel web beam provided in an embodiment of the present invention;

[0037] Figure 5 This is a diagram showing the arrangement of the discontinuous steel web provided in an embodiment of the present invention;

[0038] Figure 6 A perspective view of the prefabricated UHPC waffle base plate provided in an embodiment of the present invention.

[0039] In the figure, 1—intermittent steel web beam, 2—precast UHPC waffle bottom plate, 2-1—panel, 2-2—longitudinal rib, 2-3—transverse rib, 3—pre-drilled UHPC, 4—wet joint, 5—wet joint steel plate, 6—transverse prestressed steel strand, 7—longitudinal prestressed steel strand, 8—intermittent steel web, 8-1—outer steel web, 8-2—middle steel web, 8-3—inner steel web, 9—upper flange of steel web, 10—bottom plate of steel web, 11—reinforcement, 12—group of threaded studs, 13—I-beam, 14—semi-circular corrugated steel pipe, 15—top plate of steel web, 16—angle steel, 17—distributed threaded studs. Detailed Implementation

[0040] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0041] like Figure 1 and Figure 2 As shown, a prefabricated intermittent steel web-UHPC waffle bottom plate channel beam is composed of an intermittent steel web beam 1, a prefabricated UHPC waffle bottom plate 2, a pre-drilled UHPC 3, a wet joint 4, a wet joint steel plate 5, transverse prestressed steel strands 6, and longitudinal prestressed steel strands 7.

[0042] like Figure 2 As shown in Figure I-I, the discontinuous steel web beam 1 includes two parallel discontinuous steel web beams 1. Several precast UHPC waffle base plates 2 are installed between the two discontinuous steel web beams 1. A wet joint 4 is provided between adjacent precast UHPC waffle base plates 2. A wet joint steel plate 5 is located below the wet joint 4 and is connected to the steel web base plate 10 by bolts. The adjacent precast UHPC waffle base plates 2 are connected by casting UHPC onto the wet joint steel plate 5. Distributed threaded studs 17 and transverse prestressed steel strands 6 are provided on the wet joint steel plate 5, and adjacent precast UHPC waffle base plates 2 are connected by casting UHPC. Installing and tensioning the transverse prestressed steel strands 6 above the wet joint steel plate 5 can effectively improve the transverse crack resistance of the composite channel beam. The width of the wet joint 4 is 0.3-0.4m; the width of the wet joint steel plate 5 should not be less than the width of the wet joint 4.

[0043] like Figure 2 Medium Ⅱ-Ⅱ and Figure 4As shown, the discontinuous steel web beam 1 is composed of a discontinuous steel web 8, a steel web upper flange 9, a steel web bottom plate 10, a reinforcing member 11, and a group of threaded studs 12; the thickness of the steel web bottom plate 10 is not less than 16mm; the steel web bottom plate 10 is provided with threaded stud groups 12 at intervals; the longitudinal spacing of the threaded stud groups 12 is 1-2m; the spacing of the threaded studs inside the threaded stud groups 12 is 5-15cm; the height of the threaded studs is less than the thickness of the precast UHPC waffle bottom plate 2, and the number of threaded studs inside the threaded stud groups 12 is 8-12. The reserved holes on the prefabricated UHPC waffle base plate 2 and the threaded stud group 12 on the steel web base plate 10 are matched in position and connected to each other through the reserved holes UHPC3; the upper flange 9 of the steel web is installed on the steel web base plate 10 through the intermittent steel web 8; the side and bottom surfaces of the reinforcement 11 are respectively bolted to the intermittent steel web 8 and the steel web base plate 10;

[0044] like Figure 5 As shown, the intermittent steel web 8 consists of an outer steel web 8-1, a middle steel web 8-2, and an inner steel web 8-3. The middle steel web 8-2 is intermittently arranged in the middle of the steel web bottom plate 10. At each discontinuity on both sides of the middle steel web 8-2, the outer steel web 8-1 and the inner steel web 8-3 are arranged in parallel. The outer steel web 8-1 and the inner steel web 8-3 are symmetrical about the middle steel web 8-2 in the transverse direction, and the middle steel web 8-2 is arranged longitudinally with the outer steel web 8-1 and the inner steel web 8-3 at intervals, presenting a longitudinal arrangement similar to a corrugated steel plate. The corrugated steel plate arrangement of the intermittent steel web 8 effectively improves the prestressing introduction efficiency, significantly reduces the self-weight and steel consumption, and can provide maintenance personnel with an inspection passage.

[0045] The intermittent steel web 8 has a width of 35-45cm and a thickness of not less than 9mm, with a longitudinal spacing of 0.5-0.8m and a transverse spacing of 0.15-0.25m. The longitudinal prestressed steel strands 7 are installed on the central steel web 8-2 through anchoring and turning devices.

[0046] like Figure 3 and Figure 4 As shown, the upper flange 9 of the steel web is composed of an I-beam 13, a semi-circular corrugated steel pipe 14, and a steel web top plate 15. The upper flange 9 of the steel web uses a hollow semi-circular corrugated steel pipe 14 containing the I-beam 13, which raises the position of the neutral axis of the section, increases the bending stiffness, and further improves the prestressing introduction efficiency. The I-beam 13 is connected to the steel web top plate 15 by bolts, and the semi-circular corrugated steel pipe 14 is connected to the steel web top plate 15 by bolts passing through angle steel 16. The dimensions of the I-beam 13 should ensure that it can be contained within the semi-circular corrugated steel pipe 14. The thickness of the steel web top plate 15 is not less than 16mm.

[0047] like Figure 6As shown, the prefabricated UHPC waffle base plate 2 consists of a panel 2-1, longitudinal ribs 2-2, and transverse ribs 2-3. The length of the prefabricated UHPC waffle base plate 2 is 8-12m. The thickness of the panel 2-1 can be 6cm. The height of the longitudinal ribs 2-2 and transverse ribs 2-3 can be 20cm, and the spacing can be 0.6m. The longitudinal ribs 2-2 and transverse ribs 2-3 are arranged orthogonally and are located below the panel 2-1. The prefabricated UHPC waffle base plate 2 has reserved holes, and the size of the reserved holes is based on the threaded bolts. The arrangement of the nail group 12 is determined; the precast UHPC waffle base plate 2 is fitted onto the threaded stud group 12 through the reserved holes, positioned and installed on the steel web base plate 10, and connected to the discontinuous steel web beam 1 through the cast reserved holes UHPC 3; the precast UHPC waffle base plate 2 makes comprehensive use of the ultra-high material properties, the longitudinal and transverse rib structure of the waffle plate and the prestressing effect, which not only significantly improves the longitudinal and transverse bending stiffness and crack resistance, but also reduces the design thickness of the base plate, greatly reducing the self-weight of the structure.

[0048] Corresponding to the embodiments, the present invention proposes a construction method for a discontinuous steel web-UHPC waffle bottom plate channel beam, comprising the following steps:

[0049] (1) A simple mobile construction scaffold is erected at the construction site, and the threaded studs are passed through the reserved stud holes and fixed to the steel web bottom plate 10 and the wet joint steel plate 5 respectively, forming a group of threaded studs 12 and a distributed group of threaded studs 17.

[0050] (2) The intermittent steel web 8 is connected to the top plate 15 and the bottom plate 10 of the steel web by bolts, and the reinforcement 11 is connected to the outer steel web 8-1 and the bottom plate 10 of the steel web by bolts.

[0051] (3) The I-beam 13 is fixed to the top plate 15 of the steel web by bolt connection, and the semi-circular corrugated steel pipe 14 is connected to the top plate 15 of the steel web by bolt through the angle steel 16 to form the discontinuous steel web beam 1.

[0052] (4) Hoist the two intermittent steel web beams 1 and the wet joint steel plate 5 onto the simple mobile construction support, and use bolts to fix the wet joint steel plate 5 between the steel web bottom plate 10 of the two intermittent steel web beams 1.

[0053] (5) Lift and install several prefabricated UHPC waffle base plates 2, so that the threaded stud group 12 on the steel web base plate 10 is fitted into the reserved holes of the prefabricated UHPC waffle base plate 2, and pour the reserved hole UHPC 3.

[0054] (6) Install and tension the transverse prestressed steel strands 6 above the wet joint steel plate 5, and then cast UHPC on the wet joint steel plate 5.

[0055] (7) When the UHPC strength at the wet joint 4 reaches 90% of the design strength, release the transverse prestressed steel strand 6.

[0056] (8) Longitudinal prestressed steel strands 7 are installed and tensioned on several medium steel webs 8-2 by means of anchoring and turning devices.

[0057] This invention, through modular structural design and factory prefabrication of components, improves construction quality and significantly reduces on-site work related to formwork, reinforcement, and concrete, thereby greatly shortening the construction period and minimizing the impact on the surrounding environment. The wet joint steel plate 5 and reinforcement components 11 enhance structural stability during construction, which is beneficial for improving the torsional and distortion stiffness of the completed bridge. The wet joint steel plate 5 can serve as a permanent formwork, reducing some of the formwork erection and dismantling work.

[0058] The above embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A prefabricated intermittent steel web-UHPC waffle bottom plate channel beam, characterized in that, The channel beam consists of a discontinuous steel web beam, a prefabricated UHPC waffle bottom plate, a pre-drilled UHPC, a wet joint, a wet joint steel plate, transverse prestressed steel strands, and longitudinal prestressed steel strands. The discontinuous steel web beam includes two parallel discontinuous steel web beams. Several prefabricated UHPC waffle base plates are installed between the two discontinuous steel web beams. A wet joint is provided between two adjacent prefabricated UHPC waffle base plates. The wet joint steel plate is located below the wet joint and is connected to the discontinuous steel web beams at both ends. Distributed threaded studs and transverse prestressed steel strands are provided on the wet joint steel plate. Adjacent prefabricated UHPC waffle base plates are connected by casting UHPC. The discontinuous steel web beam includes a discontinuous steel web, an upper flange of the steel web, a bottom plate of the steel web, and a group of threaded studs; the bottom plate of the steel web is connected to the wet joint steel plate and the precast UHPC waffle bottom plate; the bottom plate of the steel web is provided with a group of threaded studs at intervals; the reserved holes in the precast UHPC waffle bottom plate and the threaded stud groups in the bottom plate of the steel web are matched in position and connected to each other through the reserved holes of the UHPC; the upper flange of the steel web is installed on the bottom plate of the steel web through the discontinuous steel web; the upper flange of the steel web is composed of an I-beam, a semi-circular corrugated steel pipe, and a top plate of the steel web; the semi-circular corrugated steel pipe contains an I-beam, the I-beam is connected to the top plate of the steel web by bolts, and the semi-circular corrugated steel pipe is connected to the top plate of the steel web by bolts passing through angle steel; The discontinuous steel web is divided into an outer steel web, a middle steel web, and an inner steel web. The middle steel web is intermittently arranged in the middle of the bottom plate of the steel web. At each discontinuity on both sides of the middle steel web, an outer steel web and an inner steel web are arranged in parallel. The outer steel web and the inner steel web are symmetrical about the middle steel web in the transverse direction. The middle steel web, the outer steel web, and the inner steel web are arranged at intervals in the longitudinal direction, presenting a longitudinal arrangement similar to a corrugated steel plate. The longitudinal prestressed steel strands are installed on the middle steel web through anchoring and turning devices.

2. The prefabricated intermittent steel web-UHPC waffle bottom plate channel beam according to claim 1, characterized in that, The dimensions of the I-beam must be such that it can be contained within the semi-circular corrugated steel pipe; the thickness of the top and bottom plates of the steel web shall not be less than 16mm.

3. The prefabricated intermittent steel web-UHPC waffle bottom plate channel beam according to claim 1, characterized in that, The discontinuous steel web beam also includes a reinforcing member, the side and bottom surfaces of which are bolted to the discontinuous steel web and the bottom plate of the steel web, respectively.

4. The prefabricated intermittent steel web-UHPC waffle bottom plate channel beam according to claim 1, characterized in that, The width of the wet joint steel plate is not less than the width of the wet joint, and the thickness is the same as that of the precast UHPC waffle base plate.

5. The prefabricated intermittent steel web-UHPC waffle bottom plate channel beam according to claim 1, characterized in that, The prefabricated UHPC waffle base plate consists of a panel, longitudinal ribs, and transverse ribs; the longitudinal ribs and transverse ribs are arranged orthogonally and located below the panel; the prefabricated UHPC waffle base plate is provided with reserved holes, the size and position of which correspond to the arrangement of the threaded stud group.

6. A construction method for a prefabricated intermittent steel web-UHPC waffle bottom plate channel beam according to any one of claims 1-5, characterized in that, The method includes the following steps: S1. Fix the threaded studs to the bottom plate of the steel web and the wet joint steel plate to form a group of threaded studs and distributed threaded studs. S2. Connect the discontinuous steel web to the top plate and bottom plate of the steel web, and connect the reinforcement to the outer steel web and the steel web. S3. Fix the I-beam to the top plate of the steel web, and connect the semi-circular corrugated steel pipe through the angle steel to the top plate of the steel web to form a discontinuous steel web beam. S4. Hoist the two discontinuous steel web beams to the construction site and fix the wet joint steel plate between the bottom plates of the steel web of the two discontinuous steel web beams. S5. Lift and install several prefabricated UHPC waffle base plates, so that the threaded studs on the steel web base plate are fitted into the reserved holes of the prefabricated UHPC waffle base plates, and pour the reserved hole UHPC3. S6. Install and tension transverse prestressed steel strands above the wet joint steel plate, and then cast UHPC on the wet joint steel plate. S7. When the UHPC strength at the wet joint reaches 90% of the design strength, release the transverse prestressed steel strands. S8. Through anchoring and turning devices, longitudinal prestressed steel strands are installed and tensioned on several intermediate steel webs.

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