Novel multi-layer composite traffic steel truss girder bridge

Abstract

The utility model relates to a novel multi-layer composite traffic steel truss girder bridge. The novel multi-layer composite traffic steel truss girder bridge comprises equal-height section truss piece sets, middle fulcrum bracket section truss piece sets, an upper-layer bridge deck system, a lower-layer bridge deck system, equal-height section supporting rods, bracket section supporting rods, bracket section transverse links, track bridge piers, track beams, hanging type stairway beams and hanging type gallery bridges. The equal-height section steel truss girder is a space truss structure system composed of an equal-height section truss piece set, an upper-layer bridge deck system, a lower-layer bridge deck system and equal-height section supporting rods. The equal-height section steel truss girder is connected with a bracket section steel truss girder composed of a middle fulcrum bracket section truss piece set, a bracket section transverse link and a bracket section supporting rod. According to the rail bridge, the rail bridge piers and the rail beams are arranged at the center positions of the upper chord nodes of the main trusses of the truss piece sets at the equal-height sections, the span application range of the steel truss bridge is expanded, the wide prospect of large-scale application is achieved, and sharing of bridge location resources in urban dense areas is promoted.

Description

Technical Field

[0001] This utility model relates to the field of multi-layer composite bridge engineering technology, specifically a novel multi-layer composite traffic steel truss bridge. Background Technology

[0002] With the rapid development of urban transportation in my country, the resources of cross-river corridors and shorelines are limited. In particular, some high-grade roads, low-grade roads, and urban rail transit systems with essentially the same trajectory repeatedly cross rivers within the same corridor, fragmenting existing land parcels and creating "sandwiched" land. This severely impacts the functionality of these land parcels and results in the occupation and waste of significant land resources. This is especially true in western my country, where rainfall is generally below the 400 mm isohyet, leading to weak ecological foundations, fragile and diverse ecosystems, and prominent problems such as soil erosion and desertification.

[0003] Currently, the design and application of bridges spanning rivers, seas, and highways are mostly concentrated in the field of road-rail or road-rail dual-purpose bridges. In the highway bridge sector, the focus is primarily on special long-span bridges such as suspension bridges. Conventional beam bridges for expressways and river-crossing bridges for different grades of highways or rail transit are rarely addressed, and relevant design standards have not been proposed. At present, the main beam cross-section forms of bridges with double-layer spatial arrangements both domestically and internationally mainly include concrete box girders, steel box girders, and steel truss composite beams. Concrete box girders have large cross-sectional dimensions and heavy self-weight, resulting in a poor aesthetic appearance in double-layer arrangements. Steel box girders use a large amount of steel, are technically difficult to manufacture, and the lower layer is generally for pedestrian access with less vehicular access. The erection methods for steel truss bridges generally include segmental hoisting, cantilever assembly, incremental launching, and segmental assembly combined with gantry crane hoisting. For bridge sites in urban areas with narrow construction sites and large span requirements, conventional construction methods such as segmental hoisting, cantilever assembly, and jacking cannot be implemented due to factors such as fabrication, transportation, and on-site welding workload. This results in problems such as high construction difficulty, high construction cost, and difficulty in ensuring construction welding quality. Utility Model Content

[0004] To address the aforementioned problems, this utility model provides a novel multi-layer composite steel truss bridge for transportation. This novel steel truss bridge structure features a clearly defined stress distribution, a simple appearance, superior seismic performance, outstanding economic efficiency, and a high degree of prefabrication. It effectively solves the design challenges of large and medium-span bridges for high-grade highways, low-grade highways, municipal roads, urban rail transit, and pedestrian-accessible bridges. It expands the applicable span range of steel truss bridges, has broad prospects for large-scale application, and can explore experiences for the integrated construction of comprehensive transportation corridors in China, promoting the sharing of bridge site resources in densely populated urban areas.

[0005] The specific technical solution of this utility model is as follows:

[0006] One of the objectives of this utility model is to provide a novel multi-layer composite traffic steel truss bridge, which includes: equal-elevation truss segment group 1, mid-support bracket segment truss segment group 2, upper bridge deck system 3, lower bridge deck system 4, equal-elevation struts 5, bracket segment struts 6, bracket segment transverse connections 7, track bridge piers 8, track beams 9, suspended staircase beams 10, and suspended corridor bridges 11.

[0007] The equal-height truss group 1 and the middle support bracket truss group 2 are connected either through the lower chord of the equal-height main truss 13 to the upper chord of the middle support bracket truss group 15, or through the lower chord of the equal-height main truss 13 to the web member of the middle support bracket truss group 17.

[0008] The equal-height truss segments 1 are connected to each other by the upper bridge deck system 3 and the lower bridge deck system 4;

[0009] The truss segments 2 of the central support bracket section are connected by the transverse connection 7 of the bracket section;

[0010] The upper bridge deck system 3 and the lower bridge deck system 4 on the outer side of the cantilever are connected by equal-elevation struts 5;

[0011] The outer lower bridge deck system 4 of the cantilever is connected to the middle support bracket section truss group 2 by the bracket section strut 6.

[0012] The track bridge pier 8 is connected to the equal-elevation section truss assembly 1;

[0013] The track beam 9 is installed on the track bridge pier 8 by means of supports;

[0014] The suspended ladder beam 10 is located below the lower bridge deck system 4 and is connected to the lower bridge deck system 4 by steel hangers 31 or vertical structures.

[0015] The suspended corridor bridge 11 is located below the lower bridge deck system 4 and is connected to the lower bridge deck system 4 by steel hangers 31 or vertical structures.

[0016] The suspended staircase beam 10 and the suspended corridor bridge 11 are connected by a sidewalk expansion joint;

[0017] Furthermore, the equal-height truss segment group 1 is formed by connecting the upper chord 12 and the lower chord 13 of the equal-height main truss through one or more equal-height main truss web members 14 via node plates;

[0018] Among them, the upper chord of the main truss of the equal height section and the lower chord of the main truss of the equal height section 13 both adopt box-shaped, open π-shaped or semi-open π-shaped cross sections;

[0019] The main truss web members 14 of the equal-elevation section adopt a triangular truss structure, are symmetrically arranged according to the center line of the bridge, and adopt box or I-shaped cross sections.

[0020] Furthermore, the middle support bracket section truss group 2 is formed by connecting the upper chord 15 and the lower chord 16 of the middle support bracket section main truss through one or more middle support bracket section main truss web members 17 via node plates.

[0021] Among them, the upper chord 15 of the main truss of the middle support bracket section and the lower chord 16 of the main truss of the middle support bracket section both adopt box-shaped, open π-shaped or semi-open π-shaped cross sections.

[0022] The main truss web member 17 of the central support bracket section adopts a triangular truss structure, is symmetrically arranged according to the center line of the bridge, and adopts a box or I-shaped cross section.

[0023] Furthermore, the upper bridge deck system 3 includes an upper steel crossbeam 18, an upper steel transverse rib 19, an upper steel longitudinal rib 20, an upper steel bridge deck 21, and an upper cast-in-place bridge deck 22.

[0024] Among them, the upper steel crossbeam 18 is set at the node of the upper chord of the main truss of the same height section, the upper steel cross rib 19 is set laterally between the upper steel crossbeam 18, the upper steel longitudinal rib 20 is set longitudinally between the upper steel crossbeam 18, the upper steel bridge deck 21 is laid on the upper steel crossbeam 18, and the upper cast-in-place bridge deck 22 is cast on the upper steel bridge deck 21.

[0025] Furthermore, the lower bridge deck system 4 includes a lower steel crossbeam 23, a lower steel transverse rib 24, a lower steel longitudinal rib 25, a lower steel bridge deck 26, and a lower cast-in-place bridge deck 27.

[0026] Among them, the lower steel crossbeam 23 is set at the node of the lower chord of the main truss of the same height section 13, the lower steel cross rib 24 is set laterally between the two lower steel crossbeams 23, the lower steel longitudinal rib 25 is set longitudinally between the two lower steel crossbeams 23, the lower steel bridge deck 26 is laid on the lower steel crossbeam 23, and the lower cast-in-place bridge deck 27 is cast on the lower steel bridge deck 26.

[0027] Furthermore, the equal-height section strut 5 and the bracket section strut 6 adopt a triangular truss structure, and the equal-height section strut 5 and the bracket section strut 6 adopt a circular, box-shaped or I-shaped cross section;

[0028] The lower chord of the main truss 16 in the middle support bracket section has a broken line or multiple parabolic curve. The lower chord of the main truss 16 in the middle support bracket section is filled with middle support ultra-high performance concrete 30 to form a steel-concrete composite lower chord.

[0029] Furthermore, the transverse connection 7 of the bracket section is composed of the upper transverse brace 28 and the lower transverse brace 29 of the bracket, which are welded to the middle support bracket section truss assembly 2 to form a stable spatial force system.

[0030] Among them, the lower cross brace 29 of the bracket is set at the node of the lower chord of the main truss of the middle support bracket section, and the number of lower cross braces 29 of the bracket is equal to the number of nodes of the lower chord of the main truss of the middle support bracket section.

[0031] Furthermore, the center positions of the nodes of the upper chord members 12 of the equal-height truss group 1 of the track bridge pier 8 and the equal-height truss group 1 are connected by welding. The number of track bridge piers 8 is the same as the number of nodes of the upper chord members 12 of the equal-height truss group, and the span of the track beam 9 is equal to the distance between the nodes of the upper chord members 12 of the equal-height truss group.

[0032] The beneficial effects of this utility model are as follows: 1. The novel multi-layer composite traffic steel truss bridge mentioned in this utility model has an upper deck that allows passage for expressways, first-class highways, and other high-grade highways, while the lower deck allows passage for second-class highways, urban municipal roads, and other low-grade highways, as well as non-motorized vehicle lanes or pedestrian walkways. The track beams allow passage for straddle-type light rail or subway systems, and the suspended staircase beams and suspended corridor bridges allow pedestrians on both sides to pass under the bridge. The multi-layer traffic bridge design concept is creative and functional. The bridge is arranged in multiple layers and operates independently, facilitating traffic organization. It can replace multi-span bridges and double-track bridges, effectively saving urban space and investment. At the same time, the multi-layer composite traffic bridge can make full use of cross-river and cross-road corridor resources, co-arranging urban rail transit, high-grade highways, low-grade roads, and pedestrian walkways, avoiding waste of land resources and damage to the ecological environment.

[0033] 2. The steel truss structure mentioned in this utility model can adopt a variable-height steel truss with brackets or a steel truss with equal-height sections. The main truss adopts a triangular truss arrangement. Both the upper and lower bridge deck systems adopt steel bridge deck panels. The equal-height truss segments, together with the upper and lower bridge deck systems, adopt a plate-truss composite load-bearing system. In this plate-truss composite structure system, the steel bridge deck and the main truss share the load, resulting in a clear load distribution. This reduces the overall steel consumption, lightens the self-weight of the superstructure, and lowers the project cost. At the same time, it has significant advantages such as no hidden structures, full-section visibility, and easy maintenance.

[0034] 3. The steel truss structure mentioned in this utility model can be configured with three to five truss segments laterally, consisting of one side truss segment + one middle truss segment + one side truss segment, or two side truss segments + one middle truss segment + two side truss segments. The side truss segments are located on both sides of the bridge, and the middle truss segment is located at the center of the bridge, corresponding to the positions of the track bridge piers. The track bridge piers arranged on the upper chord of the middle truss segment correspond to the nodes of the steel truss girder. The track bridge piers are mainly considered as force-transmitting components rather than as integral load-bearing components, with clear node force transmission, simple structure, minimal widening of the main bridge deck, and minimal overall investment. The number of track bridge piers is equal to the number of nodes of the main bridge truss, and the track beam is parallel to the bridge deck, allowing for integrated landscaping and enhancing the visual effect of the bridge.

[0035] 4. The suspended staircase beams and suspended corridor bridges mentioned in this utility model utilize a steel truss lower bridge deck system, connected to the staircase beams and corridor bridges via steel tie rods or other vertical connections. The steel tie rods and other vertical connections bear the dead loads of the staircase beams, corridor bridges, and pedestrian loads, providing vertical, lateral, and longitudinal stiffness to ensure pedestrian frequency remains within a comfortable range. The suspended staircase beams and corridor bridges eliminate the need for under-bridge supports, do not affect vehicular traffic space, and facilitate pedestrian traffic organization. Simultaneously, they reduce the steel consumption of the staircase beams and corridor bridges, making them more economical. Because they are located beneath the lower bridge deck system, the bridges offer good transparency, a lightweight and aesthetically pleasing structure, and outstanding landscape effects.

[0036] 5. The construction scheme provided by this utility model adopts a segmental assembly and gantry crane hoisting erection process. The upper bridge deck system, the lower bridge deck system and the steel truss are erected and installed simultaneously. During the erection process, the transportation and installation process of breaking down the whole into parts and combining the parts into a whole has the characteristics of factory production, assembly, modularization, intelligence, greening and informatization. It can realize advanced manufacturing, reduce the overall cost and promote industrial upgrading. It has strong applicability to the construction of bridges in areas crossing rivers and roads.

[0037] 6. The steel truss structure system of the support bracket section, the transverse connection of the bracket section, and the support bracket section struts of this utility model work together with the steel truss of the equal height section to improve the overall strength and stiffness of the bridge, solve the problem of internal force distribution at the support and mid-span of the bridge at the same height, effectively reduce the stress and deflection at the mid-span and support of the bridge, and improve the overall stiffness.

[0038] 7. This utility model adopts equal-height struts to support the upper and lower bridge deck systems on the outer side of the cantilever, solving the problem of excessive stress on the upper and lower bridge deck systems, and can also widen the width of the upper and lower bridge decks, realizing spatial reconstruction.

[0039] 8. This utility model adopts bracket section struts to support the lower bridge deck system on the outer side of the cantilever and the truss assembly of the bracket section at the middle support point, thereby changing the boundary conditions of the lower bridge deck system on the outer side of the cantilever, improving the bending bearing capacity of the lower bridge deck system on the outer side of the cantilever, and can form a support system with struts of equal height, thus widening the width of the lower bridge deck.

[0040] 9. The equal-height truss segment group and the central support bracket segment truss segment group of this utility model have the characteristics of clear force transmission path and flexible design. The chord members can increase the width and thickness of the steel plate according to the force and flexibly adjust the size. The web members have a variety of structural forms to choose from, such as I-shaped steel, welded I-beams, welded box structure, and circular structure, which increases the cross-sectional utilization rate and meets the force requirements of different spans and positions.

[0041] 10. The upper and lower bridge deck systems of this utility model adopt a longitudinal and transverse beam + steel bridge deck system to jointly bear the vertical load. The bridge deck system transfers the load to the main truss structure through the upper chord or lower chord of the main truss. The upper and lower bridge deck systems have clear stress distribution, which improves the bending and torsional resistance of the overall structure, while ensuring that the stress on the left and right truss groups is uniform.

[0042] 11. Steel transverse ribs and steel longitudinal ribs are set between the upper and lower steel crossbeams, forming a complete steel bridge deck load-bearing system with the steel bridge deck, which improves the strength and stiffness of the steel bridge deck and enhances the stability of the upper and lower bridge deck systems.

[0043] 12. This utility model of ultra-high performance concrete and modified polyurethane concrete bridge deck is lightweight and high-strength, significantly reducing the structure's self-weight. The cross-sectional dimensions of the main truss and members can also be effectively reduced, resulting in better economic indicators under high seismic conditions. The bridge deck exhibits less shrinkage and creep in the later stages, facilitating construction. The combination of steel bridge deck with ultra-high performance concrete and modified polyurethane concrete bridge deck can fully utilize the advantages of each material, improving the load-bearing capacity of the steel truss. Compared to traditional concrete-steel truss composite beams, it has a broader application prospect and represents a high-performance composite structure with comprehensive advantages throughout its entire life cycle.

[0044] 13. The lower chord of the main truss in the central support bracket section of this utility model adopts a steel-concrete composite lower chord. By utilizing the compression of the lower chord at the central support, and using ultra-high performance concrete to share the load with the lower chord, the amount of steel used in the lower chord of the main truss in the central support bracket section is reduced, the local stability of the compression zone is improved, and the overall stiffness distribution of the structure is changed. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the facade of Embodiment 1 of this utility model rotated 90° clockwise;

[0046] Figure 2 This is a schematic cross-sectional view of Embodiment 1 of the present invention at the mid-span of the bridge.

[0047] Figure 3 This is a schematic cross-sectional view of Embodiment 1 of the present invention at the support point of the bridge pier;

[0048] Figure 4 This is a cross-sectional schematic diagram of the suspended stair beam in Embodiment 1 of this utility model;

[0049] Figure 5 This is a schematic cross-sectional view of Embodiment 1 of the present invention at a suspended corridor bridge;

[0050] Figure 6 This is a schematic diagram of the upper plane of the equal-height steel truss beam structure of Embodiment 1 of this utility model rotated 90° clockwise;

[0051] Figure 7 This is a schematic diagram of the lower plane of the equal-height steel truss beam structure of Embodiment 1 of this utility model rotated 90° clockwise;

[0052] Figure 8 This is a schematic diagram of the elevation of the steel truss beam structure of the bracket section of Embodiment 1 of this utility model rotated 90° clockwise.

[0053] Figure 9 This is a schematic diagram of the lower plane of the bracket section steel truss structure of Embodiment 1 of this utility model rotated 90° clockwise;

[0054] Figure 10 This is a schematic plan view of the suspended staircase beam and suspended corridor bridge of Embodiment 1 of this utility model;

[0055] Figure 11 This is a schematic elevation view of the suspended stair beam according to Embodiment 1 of this utility model;

[0056] Figure 12 This is a schematic cross-sectional view of the suspended corridor bridge according to Embodiment 1 of this utility model;

[0057] Figure 13 This is a schematic diagram of the facade of Embodiment 2 of this utility model rotated 90° clockwise;

[0058] Figure 14 This is a schematic cross-sectional view of the bridge at the mid-span of Embodiment 2 of this utility model;

[0059] Figure 15 This is a schematic cross-sectional view of the suspended stair beam in Embodiment 2 of this utility model;

[0060] Figure 16 This is a schematic cross-sectional view of Embodiment 2 of the present invention at the suspended corridor bridge.

[0061] Figure 17 This is a schematic diagram of the upper plane of the equal-height steel truss beam structure of Embodiment 2 of this utility model rotated 90° clockwise;

[0062] Figure 18 This is a schematic diagram of the lower plane of the equal-height steel truss structure of Embodiment 2 of this utility model rotated 90° clockwise.

[0063] The diagram shows: 1. Elevation section truss assembly; 2. Mid-support bracket section truss assembly; 3. Upper bridge deck system; 4. Lower bridge deck system; 5. Elevation section strut; 6. Bracket section strut; 7. Bracket section lateral connection; 8. Track bridge pier; 9. Track beam; 10. Suspended staircase beam; 11. Suspended corridor bridge; 12. Elevation section main truss upper chord; 13. Elevation section main truss lower chord; 14. Elevation section main truss web; 15. Mid-support bracket section main truss upper chord; 16. Mid-support... 17. Main truss lower chord of the bracket section; 18. Main truss web member of the bracket section at the middle support; 19. Upper steel crossbeam; 20. Upper steel transverse rib; 21. Upper steel longitudinal rib; 22. Upper steel bridge deck; 23. Upper cast-in-place bridge deck; 24. Lower steel crossbeam; 25. Lower steel transverse rib; 26. Lower steel longitudinal rib; 27. Lower steel bridge deck; 28. Lower cast-in-place bridge deck; 29. ​​Upper cross brace of the bracket; 30. Lower cross brace of the bracket; 31. Ultra-high performance concrete at the middle support; 32. Steel hanger. Detailed Implementation

[0064] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments:

[0065] Example 1

[0066] like Figures 1-12 As shown, this utility model provides a novel multi-layer composite traffic steel truss bridge. This embodiment includes equal-elevation truss segment groups 1, mid-support bracket segment truss segment groups 2, upper bridge deck system 3, lower bridge deck system 4, equal-elevation struts 5, bracket segment struts 6, bracket segment transverse connections 7, track bridge piers 8, track beams 9, suspended staircase beams 10, and suspended corridor bridges 11. Figures 1-12 As shown.

[0067] This embodiment describes a novel multi-layer composite steel truss bridge, based on a national highway bridge spanning the Yellow River. The bridge features a four-layer structure to accommodate various traffic functions. The upper deck (system 3) houses a six-lane, two-way highway with a design load of Highway Class I. The lower deck (system 4) contains a four-lane, two-way municipal road within its truss structure, with a design load of Urban Class A. Sidewalks are provided on both sides of the cantilevered lower deck (system 4), with a design load of 5 kN / m² to accommodate high visitor numbers during holidays. Suspended staircase beams (system 10) and suspended corridor bridges (system 11) also provide sidewalks with a design load of 5 kN / m². The track beam (system 9) accommodates two-way straddle-type monorail vehicles with a design load of Type A vehicles.

[0068] The bridge span combination described in the embodiment is 112+160m, where the width of the upper bridge deck system 3 varies from 37.9 to 48.5m, and the width of the lower bridge deck system 4 varies from 36.6 to 41.8m. The width variations of the upper bridge deck system 3 and the lower bridge deck system 4 on the outer side of the cantilever are adjusted by the support of the equal-elevation section struts 5 and the bracket section struts 6. The increased lower bridge width at the central support point and the beam ends on both sides can be used as a viewing platform and for passage of the lowest-level staircase beam 10 and corridor bridge 11. The design reflects the strong applicability of this structure in expanding the bridge width, and the dimensions of the struts and bridge deck system can be adjusted according to different bridge widths to meet the design requirements.

[0069] The contour truss group 1 is divided into two contour side truss groups 1 and one contour middle truss group. The contour middle truss group is located at the center of the bridge, and the contour side truss groups are symmetrically arranged on both sides of the bridge. The contour side truss group consists of one main truss web member 14 connected to the contour main truss upper chord member 12 and the contour main truss lower chord member 13 via gusset plates. The contour middle truss group consists of two main truss web members 14 connected to the contour main truss upper chord member 12 and the contour main truss lower chord member 13 via gusset plates. The height of contour truss group 1 is 9.5m. The center distance between the two trusses in the contour middle truss group is 2.02m. The center distance between the two contour side truss groups and the contour middle truss group is 13.5m.

[0070] The central support bracket section truss assembly 2 is divided into two central support bracket section side truss assembly groups and one central support bracket section central truss assembly group. The central support bracket section central truss assembly group is located at the center of the bridge, while the central support bracket section side truss assembly groups are symmetrically arranged on both sides of the bridge. The central support bracket section side truss assembly group consists of one central support bracket section main truss web member 17 connected to the central support bracket section main truss upper chord member 15 and the central support bracket section main truss lower chord member 16 via gusset plates. The central support bracket section central truss assembly group consists of two central support bracket section main truss web members 17 connected to the central support bracket section upper chord member 15 and the central support bracket section main truss lower chord member 16 via gusset plates. The height of the two truss segments in the middle support bracket section varies from 0 to 15m. The center distance between the two truss segments in the middle truss segment of the middle support bracket section is 2.02m. The center distance between the two side truss segments of the middle support bracket section and the center truss segment of the middle support bracket section is 13.5m, which is the same as that of the truss segments of the same height.

[0071] The equal-height truss segment 1 and the mid-support bracket segment truss segment 2 are connected by welding between the lower chord 13 of the equal-height main truss and the upper chord 15 of the mid-support bracket truss segment. The bottom plate size of the lower chord 13 of the equal-height main truss is slightly smaller than the top plate size of the upper chord 15 of the mid-support bracket main truss to ensure welding space between the truss segments. During construction, bolts can be used to temporarily tighten the two steel plates to ensure welding quality.

[0072] The upper chord 12 of the main truss of the equal-height section truss group, the lower chord 13 of the main truss of the equal-height section, the upper chord 15 of the main truss of the middle support bracket section, and the lower chord 16 of the main truss of the middle support bracket section all adopt box-shaped cross sections.

[0073] The top plate of the main truss upper chord 12 of the equal-height section side truss group has a width of 1700mm and a thickness of 40mm, a bottom plate width of 760mm and a thickness of 40mm, a web plate height of 1000mm and a thickness of 40mm, and a center distance of 800mm between the two web plates.

[0074] Among them, the top plate of the upper chord of the main truss of the equal-elevation section is 3300mm wide and 40mm thick, the bottom plate is 760mm wide and 40mm thick, the distance between the two bottom plates is 2020mm, the web plate is 1000mm high and 40mm thick, and the distance between the centers of the two web plates is 800mm.

[0075] Among them, the top plate of the lower chord of the main truss of the equal-height section side truss group is 760mm wide and 40mm thick, the bottom plate is 1700mm wide and 50mm thick, the web plate is 1000mm high and 40mm thick, and the center distance between the two web plates is 800mm.

[0076] Among them, the top plate of the main truss of the equal-elevation section is 760mm wide and 40mm thick, the distance between the two top plates is 2020mm, the bottom plate is 3300mm wide and 50mm thick, the web plate is 1000mm high and 40mm thick, and the distance between the centers of the two web plates is 800mm.

[0077] The top plate of the main truss upper chord 15 in the middle support bracket section has a width of 1800mm and a thickness of 40mm, the bottom plate has a width of 760mm and a thickness of 40mm, the web plate has a height of 500mm and a thickness of 40mm, and the center distance between the two web plates is 800mm.

[0078] The top plate of the main truss upper chord 15 in the middle support bracket section has a width of 3400mm and a thickness of 40mm, a bottom plate width of 760mm and a bottom plate thickness of 40mm, a spacing of 2020mm between the two bottom plates, a web plate height of 500mm and a thickness of 40mm, and a center distance of 800mm between the two web plates.

[0079] Among them, the top plate of the main truss of the main truss lower chord 16 of the central support bracket side truss group has a width of 760mm and a thickness of 40mm, the bottom plate has a width of 1600mm and a thickness of 80-50mm, the web plate has a height of 2000-1000mm and a thickness of 70-40mm, and the center distance between the two web plates is 800mm.

[0080] Among them, the top plate of the main truss of the main truss section of the central support bracket is 760mm wide and 40mm thick, with a spacing of 2020mm between the two top plates; the bottom plate is 3300mm wide and 80-50mm thick; the web plate is 2000-1000mm high and 70-40mm thick; and the center distance between the two web plates is 800mm.

[0081] The main truss web members 14 of the equal elevation section, the main truss web members 17 of the central support bracket section, the equal elevation section struts 5, and the bracket section struts 6 all adopt a triangular truss structure, with a truss node spacing of 8m, and each member is symmetrically arranged according to the bridge centerline.

[0082] Among them, the web members 14 of the main truss of the equal-height section and the web members 17 of the main truss of the middle support bracket section adopt an I-shaped cross section. The flange width of the web members is 500-700 mm, the thickness is 25-40 mm, the web plate thickness is 20-35 mm, and the center height of the web members is 800 mm. The web members are equidistant from the web plate center distances of the upper chord member 12 of the main truss of the equal-height section, the lower chord member 13 of the main truss of the equal-height section, the upper chord member 15 of the main truss of the middle support bracket section, and the lower chord member 16 of the main truss of the middle support bracket section.

[0083] The equal-height section strut 5 and the bracket section strut 6 are made of 500x500x20mm box-shaped rolled steel.

[0084] The equal-elevation truss segments 1 are connected by the upper bridge deck system 3 and the lower bridge deck system 4.

[0085] The truss segments 2 of the central support bracket section are connected by the transverse connection 7 of the bracket section.

[0086] The upper bridge deck system 3 and the lower bridge deck system 4 on the outer side of the cantilever are supported and connected by equal-elevation struts 5.

[0087] The width of the upper deck of the single-sided cantilever bridge varies from 5.45 to 10.75m.

[0088] The lower bridge deck system 4 on the outer side of the cantilever is connected to the truss assembly 2 of the middle support bracket section through the bracket section strut 6.

[0089] The width of the lower deck system 4 on the outer side of the single-sided cantilever varies from 4.8 to 7.4m.

[0090] The upper bridge deck system 3 includes an upper steel crossbeam 18, an upper steel transverse rib 19, an upper steel longitudinal rib 20, an upper steel bridge deck 21, and an upper cast-in-place bridge deck 22.

[0091] The upper steel crossbeams 18 are located at the nodes of the upper chord 12 of the main truss at the same elevation, with the same number of nodes as the main truss. The standard spacing of the upper steel crossbeams 18 is 8m, and they are divided into upper cantilever steel crossbeams and upper inter-truss steel crossbeams. The upper steel crossbeams 18 have an I-shaped cross section, with a web thickness of 30mm, a bottom plate width of 500mm, a bottom plate thickness of 35mm, and a top plate thickness equal to that of the upper steel bridge deck 21. The upper cantilever steel crossbeams and upper inter-truss steel crossbeams are at the same height as the upper chord 12 of the main truss at the same elevation, both being 1m. The top surface of the upper steel crossbeams 18 is flush with the upper steel bridge deck 21.

[0092] The upper steel transverse ribs 19 are transversely arranged between the two upper steel crossbeams 18 according to the stress requirements of the upper steel bridge deck 21. They are divided into upper cantilever steel transverse ribs and upper inter-truss steel transverse ribs. The spacing of the upper steel transverse ribs 19 is 2.66m, which is 1 / 3 of the spacing of the upper steel crossbeams. The upper steel transverse ribs 19 adopt an I-shaped cross section with a web thickness of 20mm, a bottom plate width of 400mm, a bottom plate thickness of 25mm, and a top plate thickness equal to that of the upper steel bridge deck 21. The upper steel transverse ribs 19 are at the same height as the corresponding upper steel crossbeams 18. The top surface of the upper steel transverse ribs 19 is flush with the upper steel bridge deck 21.

[0093] The upper-layer longitudinal steel ribs 20, based on the stress requirements of the upper-layer steel bridge deck 21, are longitudinally positioned between the two upper-layer steel crossbeams 18. They are divided into upper-layer cantilever longitudinal steel ribs and upper-layer inter-truss longitudinal steel ribs. Two upper-layer cantilever longitudinal steel ribs 20 are longitudinally positioned with a spacing of 3.5m. Two upper-layer inter-truss longitudinal steel ribs 20 are also longitudinally positioned with a spacing of 5m. The upper-layer longitudinal steel ribs 20 have an I-shaped cross-section, a web thickness of 18mm, a bottom plate width of 300mm, a bottom plate thickness of 22mm, and a top plate thickness equal to that of the upper-layer steel bridge deck 21. The upper-layer longitudinal steel ribs 20 are designed with equal height, matching the height of their corresponding upper-layer steel crossbeams 18. The top surface of the upper-layer longitudinal steel ribs 20 is flush with the upper-layer steel bridge deck 21.

[0094] The upper steel bridge deck 21 includes a steel flat plate, U-shaped ribs, and plate ribs. The vehicular area of ​​the bridge deck with equal width adopts U-shaped ribs for stiffening, while the vehicular area of ​​the bridge deck with varying width adopts plate ribs for stiffening. The steel flat plate is 22mm thick, the U-shaped ribs are 10mm thick and spaced at 700mm intervals, and the plate ribs are 18mm thick, 200mm high, and spaced at 350mm intervals.

[0095] The upper cast-in-place bridge deck 22 is cast on the upper steel bridge deck 21. Since the upper layer adopts highway load and the vehicle design load is large, 5cm thick ultra-high performance concrete + 3cm asphalt concrete is used.

[0096] The lower bridge deck system 4 includes a lower steel crossbeam 23, a lower steel transverse rib 24, a lower steel longitudinal rib 25, a lower steel bridge deck 26, and a lower cast-in-place bridge deck 27.

[0097] The lower steel crossbeam 23 is located at the node of the lower chord 13 of the main truss at the same elevation, with the same number of nodes as the main truss. The standard spacing of the lower steel crossbeam is 8m, and it is divided into lower cantilever steel crossbeams and lower inter-truss steel crossbeams. The lower steel crossbeam 23 adopts an I-shaped cross section with a web thickness of 25mm, a bottom plate width of 450mm, and a bottom plate thickness of 30mm. The lower steel crossbeam 23 is designed with a uniform cross section, and its height is equal to that of the lower chord 13 of the main truss at the same elevation, both being 1m. The top surface of the lower steel crossbeam 23 is flush with the lower steel bridge deck 26.

[0098] The lower steel transverse ribs 24, arranged transversely between the two lower steel crossbeams 23 according to the stress requirements of the steel bridge deck 26, are divided into lower cantilever steel transverse ribs and lower intertrusion steel transverse ribs. The spacing of the lower steel transverse ribs 24 is 2.66m, which is 1 / 3 of the spacing of the lower steel crossbeams 23. The lower steel transverse ribs 24 adopt an I-shaped cross section with a web thickness of 16mm, a bottom plate width of 350mm, a bottom plate thickness of 20mm, and a top plate thickness equal to the thickness of the lower steel bridge deck. The lower steel transverse ribs 24 are at the same height as the corresponding steel crossbeams 23. The top surface of the lower steel transverse ribs 24 is flush with the lower steel bridge deck 26.

[0099] The lower-level longitudinal steel ribs 25, based on the stress requirements of the lower-level steel bridge deck 26, are longitudinally positioned between the two lower-level steel crossbeams 23. They are divided into lower-level cantilever longitudinal steel ribs and lower-level inter-truss longitudinal steel ribs. There are 2-3 lower-level cantilever longitudinal ribs 25 arranged longitudinally, with a spacing of 3.5m. There are 2 lower-level inter-truss longitudinal ribs 25 arranged longitudinally, with a spacing of 5m. The lower-level longitudinal steel ribs 25 have an I-shaped cross-section, a web thickness of 16mm, a bottom plate width of 300mm, a bottom plate thickness of 20mm, and a top plate thickness equal to the lower-level steel bridge deck thickness. The lower-level longitudinal steel ribs 25 are designed with equal height, matching the height of their corresponding lower-level steel crossbeams 23. The top surface of the lower-level longitudinal steel ribs 25 is flush with the lower-level steel bridge deck 26.

[0100] The lower steel bridge deck 26 includes a steel bridge deck flat plate, U-shaped ribs, and plate ribs. The vehicular area of ​​the bridge deck of equal width is reinforced with U-shaped ribs, while the non-motorized vehicle lane and pedestrian area are reinforced with plate ribs. The steel flat plate is 20mm thick, the U-shaped ribs are 10mm thick and spaced at 700mm intervals, and the plate ribs are 18mm thick, 200mm high, and spaced at 400mm intervals.

[0101] The lower-level cast-in-place bridge deck 27 is cast on the lower-level steel bridge deck 26. Since the lower level uses municipal vehicle loads and there are relatively few heavy-axle vehicles in the city, the carriageway area uses a 3cm thick modified polyurethane concrete bridge deck + 3cm thick asphalt concrete. The non-motorized vehicle lanes and pedestrian areas can use a 1cm thick modified polyurethane concrete bridge deck.

[0102] The upper bridge deck system 3 and the upper chord 12 of the equal-height truss group, and the lower bridge deck system 4 and the lower chord 13 of the equal-height main truss group are all connected by welding to form a plate girder force-bearing system that combines the bridge deck system and the truss.

[0103] The transverse connection 7 of the bracket section consists of the upper transverse brace 28 and the lower transverse brace 29 of the bracket, which are welded to the truss assembly 2 of the middle support bracket section to form a stable spatial force system.

[0104] The lower cross brace 29 of the bracket is located at the node of the lower chord of the main truss of the middle support bracket section, and the number of lower cross braces 29 is equal to the number of nodes of the lower chord of the main truss of the middle support bracket section.

[0105] The cross brace 28 on the bracket is made of 400x400x20mm box-shaped rolled steel and welded to the main truss web member 17 of the bracket section at the middle support point. In addition to providing lateral stiffness to the bracket steel truss, it can also serve as a web member to constrain and reduce the slenderness ratio of the main truss web member 17 of the bracket section at the middle support point.

[0106] The lower cross brace 29 of the bracket is a welded box-shaped member, welded to the lower chord 16 of the main truss of the bracket section at the mid-support point. The height of the lower cross brace 29 is equal to the height of the lower chord 16 of the main truss of the bracket section at different nodes, varying from 2000 to 1000 mm. The width of the box-shaped member varies from 1500 mm, 800 mm, and 500 mm from the support point to the mid-span, depending on the structural stress. The thickness of the box-shaped member is 30 mm.

[0107] The lower chord of the main truss 16 in the middle support bracket section has a 1.6-fold parabola shape.

[0108] The lower chord of the main truss 16 of the central support bracket section is filled with ultra-high performance concrete 30 to form a steel-concrete composite lower chord. The filling height of the ultra-high performance concrete 30 is 2000-1000mm, which is equal to the height of the web of the lower chord of the main truss 16 of the central support bracket section, which is 1:1.

[0109] The single-side length of the central support bracket truss group 2 is 72m, and the mid-span length of the equal-height section truss group 1 is 160m, with a length ratio of 1:2.2.

[0110] The equal-height truss assembly 1 is 9.5m high, and the central support bracket truss assembly 2 is 15m high, with a height ratio of 1:1.6.

[0111] The track bridge pier 8 is located at the center of the upper chord node 12 of the equal-height truss group. The track bridge pier 8 is welded to the upper chord node 12 of the equal-height truss group. The number of track bridge piers 8 is equal to the number of upper chord nodes 12 of the equal-height truss group. The standard spacing of the track bridge piers 8 is 8m.

[0112] Among them, track pier 8 adopts a box section, with a width of 1200mm in both directions, a wall thickness of 30mm, and a height of 7000mm. The top cap beam of the track pier adopts a box section, with a width of 5500mm, a height of 1000mm to 700mm, and a wall thickness of 30mm.

[0113] The track beam 9 of the track bridge is installed on the pier 8 of the track bridge through supports. The span of the track beam 9 is equal to the distance between the nodes of the upper chord of the equal-height truss group 12 and the spacing with the upper steel crossbeam 18. The standard spacing of the track beam 9 is 8m.

[0114] The track beam 9 adopts a box section, with a standard transverse spacing of 3700mm and a height of 2000mm. The track structure can be arranged in a 3-span configuration.

[0115] The suspended staircase beam 10 is installed on the lower bridge deck system on the outer side of the cantilever, and the staircase beam 10 and the lower bridge deck system 4 are connected by welding using steel hangers 31.

[0116] The staircase beam 10 has a span of 14mm and adopts a box-section. The bridge is 2300mm wide and 500mm high, with a top plate thickness of 14mm, a bottom plate width of 1500mm, a bottom plate thickness of 16mm, and a web thickness of 14mm. The steel hanger 31 is a GLC650UU type steel tie rod with a diameter of 50mm. The steel hanger 31 is arranged on the outside of the staircase beam 10 at an angle of 79 degrees to the staircase beam 10.

[0117] The suspended corridor bridge 11 is located below the lower bridge deck system 4, and is connected to the lower bridge deck system 4 by welding using steel hangers 31 and rectangular steel pipes.

[0118] The corridor bridge 11 has a span of 37.2 mm and adopts a box girder section. The bridge is 4600 mm wide and 800 mm high, with a top plate thickness of 16 mm, a bottom plate width of 2800 mm, a bottom plate thickness of 20 mm, and a web thickness of 16 mm. The steel hangers 31 are GLC650UU type steel tie rods with a diameter of 60 mm. The steel hangers 31 are positioned on the outer side or center of the corridor bridge 11, at angles of 130 degrees and 90 degrees to the bridge, respectively. Rectangular steel tubes, providing sufficient longitudinal and lateral stiffness to improve pedestrian comfort, are positioned on the outer side of the corridor bridge 11, at angles of 110 degrees and 90 degrees to the bridge, with dimensions of 250x250x25 mm.

[0119] The suspended staircase beams 10 and suspended corridor bridges 11 are set along the longitudinal direction of the bridge at the end of the side span of the bridge, about 8m away from the theoretical span line of the side span. Two suspended staircase beams 10 and one suspended corridor bridge 11 are set in one span to facilitate the transfer of pedestrian traffic on both sides of the steel truss beam.

[0120] The construction method of a novel multi-layer composite traffic steel truss bridge described in this embodiment is as follows:

[0121] S1. Factory-manufactured steel components including: 1. Elevation section truss assembly; 2. Mid-support bracket section truss assembly; 3. Upper bridge deck system; 4. Lower bridge deck system; 5. Elevation section struts; 6. Bracket section struts; 7. Bracket section transverse connections; 8. Track bridge piers; 9. Track beams; 11. Suspended staircase beams; 12. Suspended corridor bridges, etc.

[0122] S2. Construction of the substructure and piers;

[0123] S3. Erect temporary piers and temporary trestle bridges, and construct and install the support bracket truss assembly 2 and the transverse connection of the bracket section 7.

[0124] S4. Utilize the temporary trestle at the bridge site to install double-sided gantry cranes;

[0125] S5. Using a double-sided gantry crane, connect the central support bracket truss group 2 and the corresponding height section truss group 1 and bracket section strut 6.

[0126] S6. The main structure of the steel truss girder is erected by sequentially connecting the equal-height truss segment group 1, the lower bridge deck system 4, the upper bridge deck system 3, and the equal-height strut 5 using a gantry crane. To ensure construction quality, the gantry crane should preferably lift integral components such as the upper chord 12 of the main truss segment group and the upper bridge deck system 3, or the lower chord 13 of the main truss segment group and the lower bridge deck system 4.

[0127] S7. Hoisting and installing the track bridge piers 8 and track beams 9;

[0128] S8. Weld the suspended stair beam 10 and install the steel hanger rod 31 of the stair beam;

[0129] S9. Install the suspended walkway bridge 11, the walkway bridge steel hanger 31 and the rectangular steel pipe, and connect them to the sidewalk expansion joint;

[0130] S10. Carry out bridge deck waterproofing, paving, guardrails and other ancillary facilities works.

[0131] Example 2

[0132] like Figures 13-18 As shown, this utility model provides a novel multi-layer composite traffic steel truss bridge. This embodiment includes equal-elevation truss segment groups 1, upper bridge deck system 3, lower bridge deck system 4, equal-elevation struts 5, track bridge piers 8, track beams 9, suspended staircase beams 10, and suspended corridor bridges 11. Figures 13-18 As shown.

[0133] This embodiment describes a novel multi-layer composite steel truss bridge, based on a Class I highway bridge across the Yellow River in a certain province. The bridge is designed with a four-layer structure to accommodate various three-dimensional traffic functions. The upper deck (system 3) is a two-way eight-lane Class I highway with a design load of Highway Class I. The lower deck (system 4) has a two-way four-lane Class II highway within its truss structure with a design load of Highway Class II. Pedestrian walkways are provided on both sides of the cantilevered lower deck (system 4), with a design load of 5 kN / m² to accommodate the high volume of tourists during holidays. Suspended staircase beams (system 10) and suspended corridor bridges (system 11) also provide pedestrian walkways with a design load of 5 kN / m². The track beam (system 9) is designed for two-way straddle-type monorail vehicles with a design load of Type B vehicles.

[0134] The bridge span combination described in the embodiment is 75+120+75m, wherein the upper bridge deck system 3 has a bridge width of 43m and the lower bridge deck system 4 has a bridge width of 45m. The upper bridge deck system 3 and the lower bridge deck system 4 on the outer side of the cantilever are supported and adjusted by equal-elevation struts 5.

[0135] The contour truss group 1 is divided into two contour side truss groups 1 and one contour middle truss group. The contour middle truss group is located at the center of the bridge, and the contour side truss groups are symmetrically arranged on both sides of the bridge. The contour side truss group consists of two main truss web members 14 connected to the contour main truss upper chord member 12 and contour main truss lower chord member 13 via gusset plates. The contour middle truss group consists of two main truss web members 14 connected to the contour main truss upper chord member 12 and contour main truss lower chord member 13 via gusset plates. The height of contour truss group 1 is 10m. The center distance between the two trusses in the contour middle truss group is 2.2m, and the center distance between the two contour side truss groups and the contour middle truss group is 15.5m.

[0136] The upper chord 12 of the main truss of the equal-height truss group and the lower chord 13 of the main truss of the equal-height truss group both adopt box-shaped cross sections.

[0137] The top plate of the main truss upper chord of the equal-height side truss group is 3500mm wide and 45mm thick, the bottom plate is 860mm wide and 45mm thick, the distance between the two bottom plates is 2200mm, the web plate is 1100mm high and 45mm thick, and the center distance between the two web plates is 900mm.

[0138] Among them, the top plate of the main truss upper chord of the equal-elevation section is 3500mm wide and 55mm thick, the bottom plate is 860mm wide and 55mm thick, the distance between the two bottom plates is 2200mm, the web plate is 1100mm high and 55mm thick, and the center distance between the two web plates is 900mm.

[0139] Among them, the top plate of the equal-height section side truss group main truss equal-height section main truss lower chord 13 has a top plate width of 860mm and a thickness of 50mm, the distance between the two top plates is 2200mm, the bottom plate width is 3500mm and the thickness is 50mm, the web plate height is 1100mm and the thickness is 50mm, and the center distance between the two web plates is 900mm.

[0140] Among them, the top plate of the main truss of the equal-elevation section is 860mm wide and 58mm thick, the distance between the two top plates is 2200mm, the bottom plate is 3500mm wide and 58mm thick, the web plate is 1100mm high and 58mm thick, and the distance between the centers of the two web plates is 900mm.

[0141] The main truss web members 14 and the struts 5 of the equal elevation section both adopt a triangular truss structure, with a truss node spacing of 8.5m, and each member is arranged symmetrically according to the center line of the bridge.

[0142] Among them, the main truss web member 14 of the equal-height section adopts a box-shaped section with a width of 800mm, a thickness of 40mm, a web thickness of 40mm, and a center height of 900mm. It is equal to the center distance of the web of the upper chord member 12 of the main truss of the equal-height section and the lower chord member 13 of the main truss of the equal-height section.

[0143] The equal-elevation section strut 5 is made of 500x500x25mm box-shaped rolled steel.

[0144] The equal-height truss segments 1 are connected by the upper bridge deck system 3 and the lower bridge deck system 4;

[0145] The upper bridge deck system 3 and the lower bridge deck system 4 on the outer side of the cantilever are connected by equal-elevation struts 5;

[0146] The upper bridge deck system 3 includes an upper steel crossbeam 18, an upper steel transverse rib 19, an upper steel longitudinal rib 20, an upper steel bridge deck 21, and an upper cast-in-place bridge deck 22.

[0147] The upper steel beam 18 is located at the node position of the upper chord of the main truss at the same elevation section as the node number of the main truss. The standard spacing of the upper steel beam 18 is 8.5m, and it is divided into upper cantilever steel beams and upper inter-truss steel beams. The upper steel beam 18 adopts a box section, and the local section of the upper steel beam is set with a variable section. The height of the constant section of the upper steel beam 18 is equal to the height of the upper chord of the main truss at the same elevation section, which is 1100mm. The upper inter-truss steel beam is set with a fish-belly-shaped variable height. The height of the beam at the mid-span is 1600mm, and the height of the central beam between the trusses is 1.45 times the height of the constant section of the upper steel beam. The upper cantilever steel beam adopts a linear variable height setting. The variable section position is from the junction of the beam and the strut of the equal elevation section to the outermost edge of the cantilever. The height of the outermost edge of the cantilever is 550mm, which is 1 / 2 of the height of the constant section of the upper steel beam 18. The upper steel crossbeam has a web thickness of 20mm, a bottom plate width of 500mm, a bottom plate thickness of 30mm, and a top plate thickness equal to the upper steel bridge deck thickness. The top surface of the upper steel crossbeam 18 is flush with the upper steel bridge deck 21.

[0148] The upper steel transverse ribs 19 are transversely arranged between the two upper steel crossbeams 18 according to the stress requirements of the steel bridge deck 21. They are divided into upper cantilever steel transverse ribs and upper inter-truss steel transverse ribs. The spacing of the upper steel transverse ribs 19 is 2.83m, which is 1 / 3 of the spacing of the upper steel crossbeams. The upper steel transverse ribs 19 adopt a box-shaped section with a web thickness of 16mm, a bottom plate width of 400mm, a bottom plate thickness of 25mm, and a top plate thickness equal to that of the upper steel bridge deck. The height variation of the upper steel transverse ribs 19 and the corresponding upper steel crossbeams 18 is equal. The top surface of the upper steel transverse ribs 19 is flush with the upper steel bridge deck 21.

[0149] The upper longitudinal steel ribs 20, based on the stress requirements of the steel bridge deck 21, are only provided longitudinally as upper cantilever steel longitudinal ribs. The upper inter-truss steel longitudinal ribs can be optimized and eliminated based on the strength calculations of the upper steel beams and upper steel transverse ribs. The upper longitudinal steel ribs 20 are positioned between two upper steel transverse beams 18, with two cantilever steel longitudinal ribs 20 arranged longitudinally at a spacing of 4m. The upper longitudinal steel ribs 20 adopt an I-shaped cross-section with a web thickness of 20mm, a bottom plate width of 400mm, a bottom plate thickness of 25mm, and a top plate thickness equal to the upper steel bridge deck thickness. The upper longitudinal steel ribs 20 are designed with equal height, matching the height at the corresponding upper steel transverse beam 18 position. The top surface of the upper longitudinal steel ribs 20 is flush with the upper steel bridge deck 21.

[0150] The upper steel bridge deck 21 includes a steel flat plate, U-shaped ribs, and plate ribs. The vehicular area of ​​the bridge deck with equal width adopts U-shaped ribs for stiffening, while the vehicular area of ​​the bridge deck with varying width adopts plate ribs for stiffening. The steel flat plate is 24mm thick, the U-shaped ribs are 10mm thick and spaced at 600mm intervals, and the plate ribs are 18mm thick, 200mm high, and spaced at 300mm intervals.

[0151] The upper cast-in-place bridge deck 22 is cast on the upper steel bridge deck 21. Since the upper layer adopts highway Class I load and the vehicle design load is large, 5cm thick ultra-high performance concrete + 3cm asphalt concrete is used.

[0152] The lower bridge deck system 4 includes a lower steel crossbeam 23, a lower steel transverse rib 24, a lower steel longitudinal rib 25, a lower steel bridge deck 26, and a lower cast-in-place bridge deck 27.

[0153] The lower steel crossbeam 23 is located at the node of the lower chord 13 of the main truss at the same elevation, with the same number of nodes as the main truss. The standard spacing of the lower steel crossbeam is 8.5m, and it is divided into lower cantilever steel crossbeams and lower inter-truss steel crossbeams. The lower steel crossbeam 23 adopts a box section with a web thickness of 20mm, a bottom plate width of 500mm, and a bottom plate thickness of 30mm. The lower steel crossbeam 23 is designed with a uniform cross section, and its height is equal to that of the lower chord 13 of the main truss at the same elevation, both being 1.1m. The top surface of the lower steel crossbeam 23 is flush with the lower steel bridge deck 26.

[0154] The lower steel transverse ribs 24, arranged transversely between the two lower steel crossbeams 23 according to the stress requirements of the lower steel bridge deck 26, are divided into lower cantilever steel transverse ribs and lower intertrusion steel transverse ribs. The spacing of the lower steel transverse ribs 24 is 2.83m, which is 1 / 3 of the spacing of the lower steel crossbeams 23. The lower steel transverse ribs 24 adopt a box section with a web thickness of 16mm, a bottom plate width of 400mm, a bottom plate thickness of 25mm, and a top plate thickness equal to the thickness of the lower steel bridge deck. The lower steel transverse ribs 24 are at the same height as the corresponding lower steel crossbeams 23. The top surface of the lower steel transverse ribs 24 is flush with the lower steel bridge deck 26.

[0155] The lower-level longitudinal steel ribs 25, based on the stress requirements of the lower-level steel bridge deck 26, are only provided longitudinally as lower-level cantilever longitudinal steel ribs. The lower-level inter-truss longitudinal steel ribs can be optimized and eliminated based on the strength calculations of the steel beams and ribs. The lower-level longitudinal steel ribs 25 are located between two lower-level steel beams 23. There are 2-3 lower-level cantilever longitudinal steel ribs 25 longitudinally, with a spacing of 3.5m. There are 3 lower-level inter-truss longitudinal steel ribs 25 longitudinally, with a spacing of 4m. The lower-level longitudinal steel ribs 25 have an I-shaped cross-section, a web thickness of 20mm, a bottom plate width of 400mm, a bottom plate thickness of 25mm, and a top plate thickness equal to the lower-level steel bridge deck thickness. The lower-level longitudinal steel ribs 25 are designed with equal height, matching the height at the corresponding lower-level steel beam 23 position. The top surface of the lower-level longitudinal steel ribs 25 is flush with the lower-level steel bridge deck 26.

[0156] The lower steel bridge deck 26 includes a steel bridge deck flat plate, U-shaped ribs, and plate ribs. The vehicular area of ​​the bridge deck of equal width is reinforced with U-shaped ribs, while the non-motorized vehicle lane and pedestrian area are reinforced with plate ribs. The steel flat plate is 24mm thick, the U-shaped ribs are 10mm thick and spaced at 600mm intervals, and the plate ribs are 18mm thick, 200mm high, and spaced at 300mm intervals.

[0157] The lower cast-in-place bridge deck 27 is cast above the lower steel bridge deck 26. Since the lower layer adopts Highway Class II load, the carriageway area uses 5cm thick ultra-high performance concrete + 3cm asphalt concrete. The non-motorized vehicle lane and pedestrian area can use 1cm thick modified polyurethane concrete bridge deck.

[0158] The upper bridge deck system 3 and the upper chord 12 of the equal-height truss group, and the lower bridge deck system 4 and the lower chord 13 of the equal-height main truss group are all connected by welding to form a plate girder force-bearing system that combines the bridge deck system and the truss.

[0159] The track bridge pier 8 is located at the center of the upper chord node 12 of the equal-height truss group. The track bridge pier 8 is welded to the upper chord node 12 of the equal-height truss group. The number of track bridge piers 8 is equal to the number of upper chord nodes 12 of the equal-height truss group. The standard spacing of the track bridge piers 8 is 8.5m.

[0160] Among them, track pier 8 adopts a box section, with a width of 1300mm in both directions, a wall thickness of 32mm, and a height of 7500mm. The top cap beam of the track pier adopts a box section, with a width of 5500mm, a height of 1000mm to 700mm, and a wall thickness of 30mm.

[0161] The track beam 9 of the track bridge is installed on the pier 8 of the track bridge through supports. The span of the track beam 9 is equal to the distance between the nodes of the upper chord 12 of the equal-height truss group, and the spacing with the upper steel crossbeam 18 is also equal. The standard spacing of the track beam 9 is 8.5m.

[0162] The track beam 9 adopts a box section, with a standard transverse spacing of 4000mm and a height of 2200mm. The track structure can be arranged in a 4-span configuration.

[0163] The suspended staircase beam 10 is installed on the lower bridge deck system on the outer side of the cantilever, and the staircase beam 10 and the lower bridge deck system 4 are connected by welding using steel hangers 31.

[0164] The staircase beam 10 has a span of 12m and adopts a box girder section. The bridge is 2300mm wide and 500mm high, with a top slab thickness of 14mm, a bottom slab width of 1500mm, a bottom slab thickness of 16mm, and a web thickness of 14mm. The steel hanger 31 is a GLC460UU type steel tie rod with a diameter of 60mm. The steel hanger 31 is located on the outside of the staircase beam 10, forming a 79-degree angle with it.

[0165] The suspended corridor bridge 11 is located below the lower bridge deck system 4, and is connected to the lower bridge deck system 4 by welding using steel hangers 31.

[0166] The span of the corridor bridge 11 is 40.2 mm. Corridor bridge 11 adopts a box girder section, with a bridge width of 4600 mm, a height of 800 mm, a top plate thickness of 8 mm, a bottom plate width of 2800 mm, a bottom plate thickness of 25 mm, and a web plate thickness of 16 mm. The steel hanger 31 adopts GLC460UU type steel tie rod with a diameter of 70 mm. The steel hanger 31 is arranged on the outside or center of corridor bridge 11, at angles of 150 degrees, 130 degrees, and 90 degrees to corridor bridge 11, respectively.

[0167] The suspended staircase beams 10 and suspended corridor bridges 11 are set along the longitudinal direction of the bridge at the ends of the side spans, about 10m away from the theoretical span line of the side span. Within the 75m side span, there are 2 suspended staircase beams 10 and 1 suspended corridor bridge 11 on each side, which facilitates the transfer of pedestrian traffic on both sides of the steel truss beam.

[0168] The construction method of a novel multi-layer composite traffic steel truss bridge described in this embodiment is as follows:

[0169] S1. Factory-manufactured steel components including: 1. Elevation section truss assembly; 3. Upper bridge deck system; 4. Lower bridge deck system; 5. Elevation section struts; 8. Track bridge piers; 9. Track beams; 11. Suspended staircase beams; 12. Suspended corridor bridges, etc.

[0170] S2. Construction of the substructure and piers;

[0171] S3. Construct temporary piers and temporary trestle bridges;

[0172] S4. Utilize the temporary trestle at the bridge site to install double-sided gantry cranes;

[0173] S5. Using double-sided gantry cranes, the main structure of the steel truss girder is erected sequentially according to the following procedures: connection of equal-height truss segment group 1, lower bridge deck system 4, upper bridge deck system 3, and equal-height strut 5. To ensure construction quality, the gantry cranes should preferably lift integral components such as the upper chord 12 of the main truss segment group and the upper bridge deck system 3, or the lower chord 13 of the main truss segment group and the lower bridge deck system 4.

[0174] S6. Hoisting and installing 8 bridge piers and 9 track beams for the track bridge;

[0175] S7. Weld the suspended stair beam 10 and install the steel hanger rod 31 of the stair beam;

[0176] S8. Install the suspended walkway bridge 11 and the steel hanger 31 of the walkway bridge, and connect them to the expansion joints of the sidewalk;

[0177] S9. Carry out bridge deck waterproofing, paving, guardrails and other ancillary facilities works.

[0178] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention.

[0179] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A new type of multi-layer composite traffic steel truss girder bridge, characterized in that: The multi-layer composite traffic steel truss girder bridge comprises an equal-height section truss piece group, a middle support point bracket section truss piece group, an upper deck system, a lower deck system, an equal-height section strut, a bracket section strut, a bracket section transverse connection, a rail bridge pier, a rail beam, a hanging type stairway beam and a hanging type corridor bridge. The equal-height section truss piece group and the middle support point bracket section truss piece group are connected through equal-height section main truss lower chords and middle support point bracket truss piece group upper chords or through equal-height section main truss lower chords and middle support point bracket truss piece group web members. The equal-height section truss piece groups are connected through the upper deck system and the lower deck system. The middle support point bracket section truss piece groups are connected through the bracket section transverse connection. The upper deck system and the lower deck system on the outer side of the cantilever are supported and connected through the equal-height section strut. The lower deck system on the outer side of the cantilever and the middle support point bracket section truss piece group are supported and connected through the bracket section strut. The rail bridge pier is connected with the equal-height section truss piece group. The rail beam is installed on the rail bridge pier through a support. The hanging type stairway beam is arranged below the lower deck system and is connected with the lower deck system through a steel hanger or a vertical structure. The hanging type corridor bridge is arranged below the lower deck system and is connected with the lower deck system through a steel hanger or a vertical structure. The hanging type stairway beam and the hanging type corridor bridge are connected through a sidewalk expansion joint. The ratio of the length of one side of the middle support point bracket truss piece group to the length of the middle span of the middle support point bracket truss piece group is 1:3-1:

8. The ratio of the height of the equal-height section truss piece group to the height of the middle support point bracket truss piece group is 1:0.5-1:

4.

2. A new type of multi-layer composite traffic steel truss girder bridge according to claim 1, characterized in that: The equal-height section truss piece group is formed by single or multiple equal-height section main truss web members connecting equal-height section main truss upper chords and equal-height section main truss lower chords through a node plate. The equal-height section main truss upper chords and the equal-height section main truss lower chords adopt box-shaped, open π-shaped or semi-open π-shaped sections. The equal-height section main truss web members adopt triangular truss structures, are symmetrically arranged according to the center line of the bridge and adopt box-shaped or I-shaped sections.

3. A new type of multi-layer composite traffic steel truss girder bridge according to claim 1, characterized in that: The middle support point bracket section truss piece group is formed by single or multiple middle support point bracket section main truss web members connecting middle support point bracket section main truss upper chords and middle support point bracket section main truss lower chords through a node plate. The middle support point bracket section main truss upper chords and the middle support point bracket section main truss lower chords adopt box-shaped, open π-shaped or semi-open π-shaped sections. The middle support point bracket section main truss web members adopt triangular truss structures, are symmetrically arranged according to the center line of the bridge and adopt box-shaped or I-shaped sections.

4. A new type of multi-layer composite traffic steel truss girder bridge according to claim 1, characterized in that: The upper deck system comprises upper layer steel cross beams, upper layer steel cross ribs, upper layer steel longitudinal ribs, upper layer steel deck plates and upper layer cast-in-place deck plates. The upper layer steel cross beams are arranged at the node positions of the equal-height section main truss upper chords, the upper layer steel cross ribs are arranged transversely between the upper layer steel cross beams, the upper layer steel longitudinal ribs are arranged longitudinally between the upper layer steel cross beams, the upper layer steel deck plates are laid on the upper layer steel cross beams and the upper layer cast-in-place deck plates are cast on the upper layer steel deck plates.

5. A new type of multi-layer composite traffic steel truss girder bridge according to claim 1, characterized in that: The lower deck system comprises lower layer steel cross beams, lower layer steel cross ribs, lower layer steel longitudinal ribs, lower layer steel deck plates and lower layer cast-in-place deck plates. The lower layer steel transverse beams are arranged at the lower chord node positions of the equal-height section main truss, the lower layer steel transverse ribs are arranged transversely between two lower layer steel transverse beams, the lower layer steel longitudinal ribs are arranged longitudinally between two lower layer steel transverse beams, the lower layer steel bridge deck is arranged on the lower layer steel transverse beams, and the lower layer cast-in-situ bridge deck is cast on the lower layer steel bridge deck.

6. A new type of multi-layer composite traffic steel truss girder bridge according to claim 1, characterized in that: The equal-height section struts and the bracket section struts adopt triangular truss structures, and the equal-height section struts and the bracket section struts adopt circular, box-shaped or I-shaped cross sections; The line type of the mid-support point bracket section main truss lower chord of the mid-support point bracket section truss piece group is a broken line or a multiple parabola, the mid-support point bracket section main truss lower chord is filled with mid-support point ultra-high performance concrete, and a steel-concrete combined lower chord is formed; The bracket section transverse connection is composed of bracket upper transverse struts and bracket lower transverse struts, is respectively welded to the mid-support point bracket section truss piece group, and forms a stable space stress system. The bracket lower transverse struts are arranged at the mid-support point bracket section main truss lower chord node positions, and the number of the bracket lower transverse struts is equal to the number of the mid-support point bracket section main truss lower chord nodes.

7. A new type of multi-layer composite traffic steel truss girder bridge according to claim 1, characterized in that: The track bridge pier and the equal-height section truss piece group upper chord node central positions of the equal-height section truss piece group are welded, the number of the track bridge piers is consistent with the number of the equal-height section truss piece group upper chord nodes, and the track beam span is equal to the distance between the equal-height section truss piece group upper chord nodes.

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