Novel multi-layer composite traffic steel truss girder bridge and construction method thereof

Abstract

The invention relates to a novel multilayer composite traffic steel truss girder bridge and a construction method thereof. 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] The invention relates to the technical field of multi-layer composite bridge engineering, in particular to a novel multi-layer composite traffic steel truss bridge and a construction method thereof. Background Art

[0002] With the development of urban transportation in my country, river corridors and shoreline resources are limited. In particular, some high-grade roads and low-grade roads with basically the same direction and urban rail transit repeatedly cross the river in the same river corridor, which will cut the original land and create a "sandwich land" phenomenon, seriously affecting the function of the land and causing a large amount of land resources to be occupied and wasted. In particular, the western region of my country is generally located below the 400 mm precipitation line, with weak ecological foundation, fragile and diverse ecosystems, soil erosion, land desertification and other problems.

[0003] At present, the design and application of co-linear bridges across rivers, rivers and seas are mostly in the field of highway-railway or highway-rail dual-purpose bridges. The field of highway bridges is mainly dominated by special large-span bridges such as suspension bridges. Conventional beam bridges, highways and bridges across rivers of different grades of highways or rail transit are rarely involved, and relevant design standards have not been proposed. At present, the main cross-sectional forms of bridge main beams with double-layer space layout at home and abroad are mainly concrete box beams, steel box beams, and steel truss composite beams. The cross-sectional size of concrete box beams is large, the deadweight is large, and the double-layer layout has poor landscape; steel box beams use more steel, and the manufacturing and processing technology is difficult, and the lower layer is generally a pedestrian passage, with fewer vehicle passages. The erection and construction methods of steel truss bridges generally include segment hoisting method, cantilever assembly method, jacking method, and segment assembly and gantry crane overall hoisting method. For bridges with narrow construction sites in urban areas and larger span requirements, conventional construction methods such as segment lifting, cantilever assembly and jacking cannot be implemented in consideration of factors such as manufacturing, transportation and on-site welding workload. There are problems such as high construction difficulty, high construction cost and difficulty in ensuring the quality of construction welding. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a new type of multi-layer composite traffic steel truss bridge and its construction method. The new type of steel truss bridge has a clear force system, a simple appearance, excellent seismic performance, outstanding economy, and a high degree of assembly. It solves the design problems of large and medium span high-grade highways, low-grade highways, municipal highways, urban rails, and pedestrian co-line bridges, expands the span application range of steel truss bridges, has broad prospects for large-scale application, can explore experience for the integrated construction of domestic comprehensive transportation channels, and promote the sharing of bridge resources in densely populated urban areas.

[0005] The technical solution of the present invention is as follows:

[0006] One of the purposes of the present invention is to provide a novel multi-layer composite traffic steel truss bridge, the multi-layer composite traffic steel truss bridge comprising: an equal height section truss group 1, a middle support bracket section truss group 2, an upper bridge deck system 3, a lower bridge deck system 4, an equal height section strut 5, a bracket section strut 6, a bracket section transverse connection 7, a track bridge pier 8, a track beam 9, a hanging ladder beam 10, and a hanging gallery bridge 11;

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

[0008] The equal-height truss segments 1 are connected by an upper bridge deck system 3 and a lower bridge deck system 4;

[0009] The middle support bracket segment truss piece groups 2 are connected via bracket segment transverse connections 7;

[0010] 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-height struts 5;

[0011] The lower deck system 4 on the outer side of the cantilever is supported and connected to the middle support bracket section truss group 2 through the bracket section support rod 6;

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

[0013] The track beam 9 is installed on the track bridge pier 8 through a support;

[0014] The suspended ladder beam 10 is arranged below the lower bridge deck system 4 and connected to the lower bridge deck system 4 through a steel hanger 31 or a vertical structure;

[0015] The suspended corridor bridge 11 is arranged below the lower bridge deck system 4 and is connected to the lower bridge deck system 4 via a steel hanger 31 or a vertical structure;

[0016] The suspended stairway beam 10 is connected to the suspended corridor bridge 11 through a sidewalk expansion joint.

[0017] Furthermore, the equal-height segment truss group 1 is formed by connecting the equal-height segment main truss upper chord 12 and the equal-height segment main truss lower chord 13 through a node plate with a single or multiple equal-height segment main truss web members 14;

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

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

[0020] Furthermore, the middle support bracket segment truss piece group 2 is formed by a single or multiple middle support bracket segment main truss web members 17 connecting the middle support bracket segment main truss upper chord member 15 and the middle support bracket segment main truss lower chord member 16 through a node plate;

[0021] Among them, the upper chord rod 15 of the main truss of the middle support bracket section and the lower chord rod 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 center support bracket section adopts a triangular truss structure, is symmetrically arranged according to the center line of the bridge, and adopts a box-type or I-shaped cross-section.

[0023] Furthermore, the upper bridge deck system 3 includes an upper steel cross beam 18, an upper steel cross 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 cross beam 18 is arranged at the node position of the upper chord 12 of the equal-height main truss, the upper steel cross rib 19 is transversely arranged between the upper steel cross beams 18, the upper steel longitudinal rib 20 is longitudinally arranged between the upper steel cross beams 18, the upper steel bridge deck 21 is laid on the upper steel cross beam 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 cross beam 23 , a lower steel cross 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 cross beam 23 is arranged at the node position of the lower chord 13 of the equal-height main truss, the lower steel cross rib 24 is transversely arranged between the two lower steel cross beams 23, the lower steel longitudinal rib 25 is longitudinally arranged between the two lower steel cross beams 23, the lower steel bridge deck 26 is laid on the lower steel cross beam 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 struts 5 and the bracket section struts 6 adopt a triangular truss structure, and the equal-height section struts 5 and the bracket section struts 6 adopt a circular, box-shaped or I-shaped cross-section.

[0028] Furthermore, the bracket section transverse connection 7 is composed of a bracket upper transverse brace 28 and a bracket lower transverse brace 29, which are respectively welded to the middle support bracket section truss piece group 2 to form a stable spatial force system;

[0029] Among them, the bracket lower cross brace 29 is arranged at the node position of the lower chord rod 16 of the main truss of the middle support bracket section, and the number of the bracket lower cross brace 29 is equal to the number of the node position of the lower chord rod 16 of the main truss of the middle support bracket section.

[0030] Furthermore, the track bridge pier 8 is connected to the center positions of the nodes of the upper chord rod 12 of the contour segment truss group 1 by welding, the number of the track bridge piers 8 is consistent with the number of nodes of the upper chord rod 12 of the contour segment truss group, and the span of the track beam 9 is equal to the distance between the nodes of the upper chord rod 12 of the contour segment truss group.

[0031] Furthermore, the line shape of the lower chord 16 of the main truss of the middle support bracket section is a broken line or a multiple parabola, and the lower chord 16 of the main truss of the middle support bracket section is filled with middle support ultra-high performance concrete 30 to form a steel-concrete composite lower chord, and the ratio of the filling height of the middle support ultra-high performance concrete 30 to the web height of the lower chord 16 of the main truss of the middle support bracket section is 1:1 to 1:5.

[0032] Furthermore, the ratio of the length of one side of the middle support bracket truss piece group 2 to the middle span length of the middle support bracket truss piece group 2 is 1:3 to 1:8;

[0033] The ratio of the height of the equal-height truss piece group 1 to the middle support bracket truss piece group 2 is 1:0.5 to 1:4.

[0034] Another object of the present invention is to provide a novel construction method for a multi-layer composite traffic steel truss bridge, comprising:

[0035] S1. Factory-made equal-height section equal-height section truss group 1, middle support bracket section truss group 2, upper bridge deck system 3, lower bridge deck system 4, equal-height section struts 5, bracket section struts 6, bracket section transverse connections 7, track bridge piers 8, track beams 9, suspended ladder beams 11, and suspended gallery bridges 12;

[0036] S2. Construction of lower foundation and bridge piers;

[0037] S3. Set up temporary piers and temporary trestle, install the support bracket truss group 2 and the bracket section lateral connection 7;

[0038] S4. Use the temporary trestle at the bridge location to install double-sided gantry cranes;

[0039] S5. Using the double-sided gantry crane, connect the middle support bracket truss group 2 and the corresponding position of the equal height segment truss group 1 and the bracket segment support rod 6;

[0040] S6. The main structure of the steel truss is erected by connecting the equal-height segment truss group 1, the lower bridge deck system 4, the upper bridge deck system 3, and the equal-height segment support rod 5 in sequence through the gantry crane; the gantry crane hoisting assembly is an integral component of the upper chord rod 12 of the main truss of the equal-height segment truss group and the upper bridge deck system 3 or an integral component of the lower chord rod 13 of the main truss of the equal-height segment truss group and the lower bridge deck system 4;

[0041] S7. Hoisting and constructing the track bridge pier 8 and the track bridge rail beam 9;

[0042] S8. Welding hanging ladder beam 10, installing ladder beam steel hanger 31 or vertical structure;

[0043] S9. Install the suspended corridor bridge 11, the corridor bridge steel hanger 31 or the vertical structure, and connect the sidewalk expansion joint;

[0044] S10. Carry out bridge deck waterproofing, pavement, guardrails and ancillary facilities engineering.

[0045] The beneficial effects of the present invention are as follows: 1. The new multi-layer composite traffic steel truss bridge mentioned in the present invention has an upper bridge deck that can pass through high-grade roads such as expressways and first-class highways, and a lower bridge deck that can pass through low-grade roads such as second-class highways and urban municipal roads and non-motorized vehicle lanes or pedestrian landscape trails. The track beam can pass through urban rail transit such as straddle-type light rail or subway, and the suspended ladder beam and suspended corridor bridge can allow people on the left and right sides to pass each other under the bridge. The design concept of the multiple traffic bridge is creative and functional. The bridge is arranged in multiple layers and operates independently, which is convenient for 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 the resources of cross-river and cross-road corridors, and arrange urban rail transit, high-grade highways, low-grade roads and pedestrian roads in the same line, avoiding the waste of land resources and the damage to the ecological environment.

[0046] 2. The steel truss structure mentioned in the present invention can adopt a variable height steel truss with a bracket or a steel truss of equal height. The main truss adopts a triangular truss arrangement. The upper and lower deck systems both adopt a steel bridge deck system. The equal height truss group and the upper and lower deck systems adopt a plate-truss combined force system. The plate-truss combined structural system, the steel bridge deck and the main truss are jointly stressed, and the force is clear. While reducing the comprehensive steel consumption, reducing the deadweight of the upper structure, and reducing the project cost, it has the significant advantages of no hidden structure, full section visibility and easy maintenance.

[0047] 3. The steel truss structure mentioned in the present invention can be provided with three to five truss groups in the horizontal direction, which are divided into one side truss group + one middle truss group + one side truss group or two side truss groups + one middle truss group + two side truss groups. The side truss groups are located on both sides of the bridge, and one middle truss group is located in the center of the bridge, corresponding to the position of the track bridge piers. The track bridge piers arranged on the upper chord of the middle truss group are arranged corresponding to the steel truss nodes. The setting of the track bridge piers is mainly considered as force transmission components rather than integral force-bearing components. The node force transmission is clear, the structure is simple, the widening of the main bridge deck is minimized, and the overall investment is minimized. The number of track bridge piers is equal to that of the main truss nodes of the main bridge. The track beam body is parallel to the bridge deck, which can create a landscape as a whole and enhance the visual effect of the bridge.

[0048] 4. The suspended stairway beam and suspended corridor bridge mentioned in the present invention utilize the lower bridge deck system of steel trusses to connect the lower bridge deck system and the stairway beam and corridor bridge through steel tie rods or other vertical connections. The setting of steel tie rods and other vertical connections bears the constant load of the stairway beam, the constant load of the corridor bridge and the crowd load, and provides vertical stiffness, lateral stiffness and longitudinal stiffness for the stairway beam and corridor bridge, ensuring that the pedestrian frequency is in a comfortable zone. The suspended stairway beam and corridor bridge avoid the need to set up bearings under the bridge, do not affect the vehicle space on the bridge, and are conducive to the organization of pedestrian traffic. At the same time, the amount of steel used in the stairway beam and corridor bridge can be reduced, and the cost is more economical. Since they are arranged under the lower bridge deck system, the bridge has good permeability, a light and beautiful structure, and outstanding landscape effects.

[0049] 5. The construction scheme provided by the present invention adopts the erection technology of segment assembly and overall lifting by gantry crane. The upper bridge deck system, the lower bridge deck system and the steel trusses are erected and installed synchronously. During the erection process, through the transportation and installation process of breaking the whole into parts and combining the parts into a whole, it has the characteristics of factoryization, assembly, modularization, intelligence, greenness, and informatization. It can realize advanced manufacturing, reduce comprehensive costs, and promote industrial upgrading. It has strong applicability to the construction of bridges across rivers and roads.

[0050] 6. The bracket steel truss structure system composed of the support bracket section truss group, the bracket section transverse connection, and the bracket section struts in the present invention works together with the equal-height section steel trusses to improve the strength and rigidity of the entire bridge, solve the internal force distribution at the support points and mid-span of equal-height bridges, effectively reduce the stress and deflection at the mid-span and support points of the bridge, and improve the overall rigidity.

[0051] 7. The present invention adopts equal-height struts to support the upper and lower deck systems on the outer sides of the cantilever, thereby solving the problem of excessive stress on the cantilevers of the upper and lower deck systems, and can widen the width of the upper and lower decks to achieve space reconstruction.

[0052] 8. The present invention adopts bracket section struts to support the cantilever outer lower bridge deck system and the middle support bracket section truss group, so as to change the boundary conditions of the cantilever outer lower bridge deck system, improve the bending bearing capacity of the cantilever outer lower bridge deck system, and form a support system with equal height section struts to widen the width of the lower bridge deck.

[0053] 9. The equal-height truss segment group and the middle support bracket segment truss segment group of the present invention have the characteristics of clear force transmission path and flexible design. The chord can increase the width and thickness of the steel plate according to the force, and the size can be flexibly adjusted. The web member has a variety of structural forms such as I-shaped steel, welded I-shaped steel, welded box-type structure, circular structure, etc., which increases the cross-section utilization rate and meets the force requirements of different spans and different positions.

[0054] 10. The upper and lower deck systems of the present invention adopt a longitudinal and transverse beam + steel bridge deck system to jointly bear the vertical load. The deck system transfers the load to the main truss structure through the main truss upper chord or the main truss lower chord. The upper and lower deck systems are clearly stressed, which improves the bending and torsion resistance of the overall structure, and makes the left and right side truss groups evenly stressed.

[0055] 11. Steel transverse ribs and steel longitudinal ribs are arranged between the upper steel transverse beams and the lower steel transverse beams, forming a complete steel bridge deck force system with the steel bridge deck, thereby improving the strength and rigidity of the steel bridge deck and the stability of the upper and lower bridge deck systems.

[0056] 12. The ultra-high performance concrete and modified polyurethane concrete bridge deck of the present invention are light in weight and high in strength, which significantly reduces the deadweight of the structure. The cross-sectional dimensions of the main trusses and rods can also be effectively reduced, and have good economic indicators under high seismic conditions. The bridge deck has small shrinkage creep in the later stage, and the construction is convenient. The combination of steel bridge deck with ultra-high performance concrete and modified polyurethane concrete bridge deck can give full play to the advantages of each material and improve the bearing capacity of steel trusses. Compared with traditional concrete-steel truss composite beams, it has broader application prospects and is a high-performance composite structure with comprehensive advantages throughout its lifespan.

[0057] 13. In the present invention, the lower chord of the main truss of the middle support bracket section adopts a steel-concrete composite lower chord, and the middle support lower chord is compressed, and the filling ultra-high performance concrete is used to bear the force together with the lower chord, which not only reduces the steel consumption of the lower chord of the main truss of the middle support bracket section, but also improves the local stability of the compressed area and changes the overall stiffness distribution of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a schematic diagram of the vertical surface of Example 1 of the present invention rotated 90° clockwise;

[0059] Figure 2 It is a cross-sectional schematic diagram of embodiment 1 of the present invention at the mid-span of the bridge;

[0060] Figure 3 It is a cross-sectional schematic diagram of embodiment 1 of the present invention at a pier support point in a bridge;

[0061] Figure 4 It is a cross-sectional schematic diagram of embodiment 1 of the present invention at a hanging ladder beam;

[0062] Figure 5 It is a cross-sectional schematic diagram of embodiment 1 of the present invention at a suspended corridor bridge;

[0063] Figure 6 This is a schematic diagram of the upper plane of the equal-height steel truss structure of Example 1 of the present invention rotated 90° clockwise;

[0064] Figure 7This is a schematic diagram of the lower plane of the equal-height steel truss structure of Example 1 of the present invention rotated 90° clockwise;

[0065] Figure 8 This is a schematic diagram of the vertical surface of the bracket section steel truss structure of Example 1 of the present invention rotated 90° clockwise;

[0066] Fig. 9 This is a schematic diagram of the lower plane of the bracket section steel truss structure of Example 1 of the present invention rotated 90° clockwise;

[0067] Fig.10 It is a schematic plan view of a suspended ladder beam and a suspended corridor bridge according to Embodiment 1 of the present invention;

[0068] Fig.11 This is a schematic elevation diagram of a hanging ladder beam according to Embodiment 1 of the present invention;

[0069] Fig.12 Schematic diagram of the cross section of the suspended corridor bridge according to Embodiment 1 of the present invention;

[0070] Fig.13 This is a schematic diagram of the elevation of Example 2 of the present invention rotated 90° clockwise;

[0071] Fig.14 It is a cross-sectional schematic diagram of embodiment 2 of the present invention at the mid-span of the bridge;

[0072] Fig.15 It is a cross-sectional schematic diagram of embodiment 2 of the present invention at a hanging ladder beam;

[0073] Fig.16 It is a cross-sectional schematic diagram of embodiment 2 of the present invention at a suspended corridor bridge;

[0074] Fig.17 This is a schematic diagram of the upper plane of the equal-height steel truss structure of Example 2 of the present invention rotated 90° clockwise;

[0075] Fig.18 This is a schematic diagram of the lower plane of the equal-height steel truss structure of Example 2 of the present invention rotated 90° clockwise.

[0076] As shown in the figure: 1. Equal height section truss group; 2. Middle support bracket section truss group; 3. Upper bridge deck system; 4. Lower bridge deck system; 5. Equal height section struts; 6. Bracket section struts; 7. Bracket section transverse connection; 8. Track bridge piers; 9. Track beams; 10. Suspended ladder beams; 11. Suspended corridor bridge; 12. Equal height section main truss upper chord; 13. Equal height section main truss lower chord; 14. Equal height section main truss web; 15. Middle support bracket section main truss upper chord; 16. Middle support 1. Lower chord of main truss of bracket section at the middle support point; 17. Web of main truss of bracket section at the middle support point; 18. Upper steel cross beam; 19. Upper steel transverse rib; 20. Upper steel longitudinal rib; 21. Upper steel bridge deck; 22. Upper cast-in-place bridge deck; 23. Lower steel cross beam; 24. Lower steel transverse rib; 25. Lower steel longitudinal rib; 26. Lower steel bridge deck; 27. Lower cast-in-place bridge deck 28; Upper cross brace of bracket; 29. ​​Lower cross brace of bracket; 30. Ultra-high performance concrete at the middle support point; 31. Steel hanger. DETAILED DESCRIPTION

[0077] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific embodiments:

[0078] Example 1

[0079] like Figures 1 to 12 As shown, the present invention provides a novel multi-layer composite traffic steel truss bridge and a construction method thereof. This embodiment includes an equal height section truss group 1, a middle support bracket section truss group 2, an upper bridge deck system 3, a lower bridge deck system 4, an equal height section support rod 5, a bracket section support rod 6, a bracket section transverse connection 7, a track bridge pier 8, a track beam 9, a hanging ladder beam 10 and a hanging corridor bridge 11, as shown in FIG. Figures 1 to 12 shown.

[0080] The novel multi-layer composite traffic steel truss bridge described in this embodiment relies on a national highway across the Yellow River. The bridge is designed with a four-layer structure to meet the passage of various three-dimensional traffic functions. Among them, the upper bridge deck system 3 is set with a two-way six-lane highway, and the design load is highway level I. The lower bridge deck system 4 is set with a two-way four-lane municipal highway in the truss, and the design load is city level A. Sidewalks are set on both sides of the cantilever of the lower bridge deck system 4. Considering the needs of dense crowds on holidays, the design load is 5kN / m2. The suspended ladder beam 10 and the suspended corridor bridge 11 are set with sidewalks, and the design load is 5kN / m2. The track beam 9 is set with a two-way straddle-type monorail vehicle, and the vehicle design load is type A vehicle.

[0081] The bridge span combination described in the embodiment is 112+160m, wherein the bridge width of the upper bridge deck system 3 varies from 37.9 to 48.5m, and the bridge width of the lower bridge deck system 4 varies from 36.6 to 41.8m. The changes in the bridge widths of 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 the equal-height section struts 5 and the bracket section struts 6. The increased lower bridge width at the middle fulcrum and the beam ends on both sides can be used as a viewing platform and for the passage of the lowest staircase beam 10 and the corridor bridge 11. The design reflects the strong applicability of the structure in expanding the bridge width, and the sizes of the struts and the bridge deck system can be adjusted according to the different bridge widths to meet the design requirements.

[0082] The equi-height segment truss group 1 is divided into two equi-height segment side truss groups 1 and one equi-height segment middle truss group. The equi-height segment middle truss group is located at the center of the bridge, and the equi-height segment side truss groups are symmetrically arranged on both sides of the bridge. The equi-height segment side truss group is composed of one main truss web member 14 connected to the equi-height segment main truss upper chord 12 and the equi-height segment main truss lower chord 13 through a node plate, and the equi-height segment middle truss group is composed of two main truss web members 14 connected to the equi-height segment main truss upper chord 12 and the equi-height segment main truss lower chord 13 through a node plate. The equi-height segment truss group 1 has a truss height of 9.5m, and the center distance between the two trusses in the equi-height segment middle truss group is 2.02m. The center distances between the two equi-height segment side truss groups and the equi-height segment middle truss group are both 13.5m.

[0083] The middle support bracket section truss piece group 2 is divided into two middle support bracket section side truss piece groups and one middle support bracket section middle truss piece group. The middle support bracket section middle truss piece group is located at the center of the bridge, and the middle support bracket section side truss piece group is symmetrically arranged on both sides of the bridge. The middle support bracket section side truss piece group is composed of one middle support bracket section main truss web member 17 connected to the middle support bracket section main truss upper chord 15 and the middle support bracket section main truss lower chord 16 through a node plate, and the middle support bracket section middle truss piece group is composed of two middle support bracket section main truss web members 17 connected to the middle support bracket section upper chord 15 and the middle support bracket section main truss lower chord 16 through a node plate. The height variation range of the truss group 2 of the middle support bracket section is 0 to 15m, the center distance between the two trusses in the middle truss group of the middle support bracket section is 2.02m, and the center distance between the two side truss groups of the middle support bracket section and the middle truss group of the middle support bracket section is 13.5m, which is equal to the truss groups of the same height sections.

[0084] The equal height section truss group 1 and the middle support bracket section truss group 2 are connected by welding through the equal height section main truss lower chord 13 and the middle support bracket truss group upper chord 15. The bottom plate size of the equal height section main truss lower chord 13 is slightly smaller than the top plate size of the middle support bracket section main truss upper chord 15 to ensure the welding space between the truss groups. During construction, bolts can be used to temporarily press the two steel plates to ensure welding quality.

[0085] The main truss upper chord 12 of the equal height section truss group, the lower chord 13 of the equal height section main truss, the upper chord 15 of the middle support bracket section main truss, and the lower chord 16 of the middle support bracket section main truss all adopt box-shaped sections.

[0086] The top plate width of the upper chord 12 of the main truss of the equal-height side truss group is 1700mm, the thickness is 40mm, the bottom plate width is 760mm, the thickness is 40mm, the web height is 1000mm, the thickness is 40mm, and the center distance between the two webs is 800mm.

[0087] Among them, the top plate width of the upper chord 12 of the main truss of the equal-height section middle truss group is 3300mm, the thickness is 40mm, the bottom plate width is 760mm, the bottom plate thickness is 40mm, the middle distance between the two bottom plates is 2020mm, the web height is 1000mm, the thickness is 40mm, and the center distance between the two webs is 800mm.

[0088] Among them, the top plate width of the lower chord 13 of the main truss of the equal height section side truss group is 760mm, the thickness is 40mm, the bottom plate width is 1700mm, the thickness is 50mm, the web height is 1000mm, the thickness is 40mm, and the center distance between the two webs is 800mm.

[0089] Among them, the top plate width of the lower chord 13 of the main truss of the equal height section middle truss group is 760mm, the thickness is 40mm, the middle distance between the two top plates is 2020mm, the bottom plate width is 3300mm, the thickness is 50mm, the web height is 1000mm, the thickness is 40mm, and the center distance between the two webs is 800mm.

[0090] The top plate width of the upper chord 15 of the main truss of the middle support bracket section is 1800mm, the thickness is 40mm, the bottom plate width is 760mm, the thickness is 40mm, the web height is 500mm, the thickness is 40mm, and the center distance between the two webs is 800mm.

[0091] The top plate width of the upper chord 15 of the main truss of the middle support bracket section is 3400mm, the thickness is 40mm, the bottom plate width is 760mm, the bottom plate thickness is 40mm, the middle distance between the two bottom plates is 2020mm, the web height is 500mm, the thickness is 40mm, and the center distance between the two webs is 800mm.

[0092] Among them, the top plate width of the main truss lower chord 16 of the middle support bracket section of the main truss of the middle support bracket side truss group is 760mm, the thickness is 40mm, the bottom plate width is 1600mm, the thickness is 80-50mm, the web height is 2000-1000mm, the thickness is 70-40mm, and the center distance between the two webs is 800mm.

[0093] Among them, the top plate width of the main truss lower chord 16 of the middle fulcrum bracket middle truss section of the main truss of the middle fulcrum bracket middle truss group is 760mm, the thickness is 40mm, the middle distance between the two top plates is 2020mm, the bottom plate width is 3300mm, the thickness is 80~50mm, the web height is 2000~1000mm, the thickness is 70~40mm, and the center distance between the two webs is 800mm.

[0094] The equal-height section main truss web members 14, the middle support section main truss web members 17, the equal-height section struts 5, and the bracket section struts 6 all adopt a triangular truss structure, the truss node spacing is 8m, and each member is symmetrically arranged according to the center line of the bridge.

[0095] The web members 14 of the equal height section main truss and the web members 17 of the middle support bracket section adopt I-shaped cross-sections, with web member flange widths of 500-700 mm, thicknesses of 25-40 mm, web plate thicknesses of 20-35 mm, and web member center heights of 800 mm, which are equidistant from the web center centers of the upper chords 12 of the equal height section main truss of the equal height section truss group, the lower chords 13 of the equal height section main truss of the equal height section main truss of the equal height section truss group, the upper chords 15 of the middle support bracket section main truss, and the lower chords 16 of the middle support bracket section main truss of the middle support bracket section main truss of the middle support bracket section main truss.

[0096] The equal height section support rods 5 and the bracket section support rods 6 are made of 500x500x20mm box-shaped rolled steel.

[0097] The equal-height truss segments 1 are connected via an upper bridge deck system 3 and a lower bridge deck system 4 .

[0098] The middle support bracket section truss piece groups 2 are connected via bracket section transverse connections 7 .

[0099] 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-height struts 5 .

[0100] The width of the upper deck system 3 on the outer side of the single-sided cantilever varies from 5.45 to 10.75 m.

[0101] The cantilever outer side lower deck system 4 is supported and connected to the middle support bracket section truss piece group 2 through the bracket section strut 6.

[0102] The width of the lower deck system 4 on the outer side of the single-sided cantilever varies from 4.8 to 7.4 m.

[0103] The upper bridge deck system 3 includes an upper steel cross beam 18 , an upper steel cross rib 19 , an upper steel longitudinal rib 20 , an upper steel bridge deck 21 and an upper cast-in-place bridge deck 22 .

[0104] The upper steel beam 18 is set at the node position of the upper chord 12 of the equal-height main truss, which is consistent with the number of main truss nodes. The standard spacing of the upper steel beam 18 is 8m, which is divided into the upper cantilever steel beam and the upper inter-truss steel beam. The upper steel beam 18 adopts an I-shaped 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 beam, the upper inter-truss steel beam and the equal-height main truss upper chord 12 are equal in height, all of which are 1m. The top surface of the upper steel beam 18 is flush with the upper steel bridge deck 21.

[0105] The upper steel transverse rib 19 is transversely arranged between two upper steel beams 18 according to the force requirements of the upper steel bridge deck 21, and is divided into upper cantilever steel transverse ribs and upper truss steel transverse ribs. The upper steel transverse rib 19 is arranged at a spacing of 2.66m, which is 1 / 3 of the spacing of the upper steel beams. The upper steel transverse rib 19 adopts an I-shaped 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 rib 19 is equal in height to the corresponding upper steel beam 18. The top surface of the upper steel transverse rib 19 is flush with the upper steel bridge deck 21.

[0106] The upper steel longitudinal rib 20 is longitudinally arranged between two upper steel cross beams 18 according to the force requirements of the upper steel bridge deck 21, and is divided into an upper cantilever steel longitudinal rib and an upper truss steel longitudinal rib. Two upper cantilever steel longitudinal ribs 20 are longitudinally arranged, and the spacing between the upper steel longitudinal ribs 20 is 3.5m. Two upper truss steel longitudinal ribs 20 are longitudinally arranged, and the spacing between the steel longitudinal ribs 20 is 5m. The upper steel longitudinal rib 20 adopts an I-shaped section, with 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 steel bridge deck 21. The upper steel longitudinal rib 20 is designed at the same height, and is equal to the height at the corresponding upper steel cross beam 18 position. The top surface of the upper steel longitudinal rib 20 is flush with the upper steel bridge deck 21.

[0107] The upper steel bridge deck 21 includes a steel flat plate, U-shaped ribs, and plate ribs. The U-shaped rib reinforcement is used in the vehicle driving area of ​​the equal-width section of the bridge deck, and the plate rib reinforcement is used in the vehicle driving area of ​​the variable-width section of the bridge deck. The thickness of the steel flat plate is 22 mm, the wall thickness of the U-shaped rib is 10 mm, the arrangement spacing is 700 mm, the plate rib thickness is 18 mm, the height is 200 mm, and the arrangement spacing is 350 mm.

[0108] The upper cast-in-place bridge deck 22 is cast on the upper steel bridge deck 21. Since the upper layer adopts the highway load and the vehicle design load is large, 5 cm thick ultra-high performance concrete + 3 cm asphalt concrete is used.

[0109] The lower bridge deck system 4 includes a lower steel cross beam 23 , a lower steel cross rib 24 , a lower steel longitudinal rib 25 , a lower steel bridge deck 26 and a lower cast-in-place bridge deck 27 .

[0110] The lower steel beam 23 is set at the node position of the lower chord 13 of the equal-height main truss, which is consistent with the number of main truss nodes. The standard spacing of the lower steel beam is 8m, which is divided into the lower cantilever steel beam and the lower inter-truss steel beam. The lower steel beam 23 adopts an I-shaped section, with a web thickness of 25mm, a bottom plate width of 450mm, and a bottom plate thickness of 30mm. The lower steel beam 23 is designed with a uniform cross-section, and the uniform cross-section height of the lower steel beam 23 is equal to the height of the lower chord 13 of the equal-height main truss, both of which are 1m; the top surface of the lower steel beam 23 is flush with the lower steel bridge deck 26.

[0111] The lower steel transverse rib 24 is transversely arranged between two lower steel beams 23 according to the force requirements of the steel bridge deck 26, and is divided into lower cantilever steel transverse ribs and lower inter-truss steel transverse ribs. The spacing of the lower steel transverse rib 24 is 2.66m, which is 1 / 3 of the spacing of the lower steel beams 23. The lower steel transverse rib 24 adopts an I-shaped 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 that of the lower steel bridge deck. The lower steel transverse rib 24 is equal in height to the corresponding steel beam 23. The top surface of the lower steel transverse rib 24 is flush with the lower steel bridge deck 26.

[0112] The lower steel longitudinal rib 25 is longitudinally arranged between two lower steel beams 23 according to the force requirements of the lower steel bridge deck 26, and is divided into lower cantilever steel longitudinal ribs and lower truss steel longitudinal ribs. Two to three lower cantilever steel longitudinal ribs 25 are longitudinally arranged, and the spacing between the lower steel longitudinal ribs 25 is 3.5m. Two lower truss steel longitudinal ribs 25 are longitudinally arranged, and the spacing between the lower steel longitudinal ribs 25 is 5m. The lower steel longitudinal rib 25 adopts an I-shaped section, with a web thickness of 16mm, a bottom plate width of 300mm, a bottom plate thickness of 20mm, and a top plate thickness equal to that of the lower steel bridge deck. The lower steel longitudinal rib 25 is designed at the same height, and is equal to the height at the corresponding lower steel beam 23. The top surface of the lower steel longitudinal rib 25 is flush with the lower steel bridge deck 26.

[0113] The lower steel bridge deck 26 includes a steel bridge deck flat plate, U-shaped ribs, and plate ribs. The vehicle driving area of ​​the equal-width section of the bridge deck adopts U-shaped rib reinforcement, and the non-motorized vehicle lane and pedestrian area adopt plate rib reinforcement. The steel flat plate is 20 mm thick, the U-shaped rib wall is 10 mm thick, and the arrangement spacing is 700 mm. The plate rib is 18 mm thick, the height is 200 mm, and the arrangement spacing is 400 mm.

[0114] The lower cast-in-place bridge deck 27 is cast on the lower steel bridge deck 26. Since the lower layer adopts municipal vehicle load and there are few heavy-axle vehicles in the city, the carriageway area adopts 3cm modified polyurethane concrete bridge deck + 3cm asphalt concrete. The non-motorized vehicle lane and pedestrian area can adopt 1cm thick modified polyurethane concrete bridge deck.

[0115] The upper deck system 3 and the upper chord 12 of the equal-height truss group, and the lower deck system 4 and the lower chord 13 of the equal-height main truss of the equal-height truss group are all connected by welding to form a plate-truss force system combining the deck system and the truss.

[0116] The bracket section transverse connection 7 is composed of a bracket upper transverse brace 28 and a bracket lower transverse brace 29, which are welded to the middle support bracket section truss piece group 2 to form a stable spatial force system.

[0117] The bracket lower cross brace 29 is arranged at the node position of the lower chord rod 16 of the main truss of the middle support bracket section, and the number of the bracket lower cross brace 29 is equal to the number of the node position of the lower chord rod 16 of the main truss of the middle support bracket section.

[0118] The upper cross brace 28 of the bracket is made of 400x400x20mm box-shaped rolled steel, which is welded to the web member 17 of the middle support bracket section main truss. In addition to providing lateral stiffness to the bracket steel truss, it can also serve as a web member constraint to reduce the slenderness ratio of the web member 17 of the middle support bracket section main truss.

[0119] The bracket lower cross brace 29 is a welded box-shaped rod, which is welded on the lower chord rod 16 of the middle support bracket section main truss. The height of the bracket lower cross brace 29 is equal to the height of the lower chord rod 16 of the middle support bracket section main truss at different nodes, and the variation range is 2000-1000mm. The width of the box-shaped rod is 1500mm, 800mm, and 500mm from the support to the mid-span according to the structural force, and the thickness of the box-shaped rod is 30mm.

[0120] The line shape of the lower chord 16 of the main truss of the middle support bracket section is a 1.6-order parabola.

[0121] The middle support bracket section main truss lower chord 16 is filled with middle support ultra-high performance concrete 30 to form a steel-concrete composite lower chord. The filling height of the middle support ultra-high performance concrete 30 ranges from 2000 to 1000 mm, which is equal to the web height of the middle support bracket section main truss lower chord 16, that is, 1:1.

[0122] The single-side length of the middle support bracket truss group 2 is 72m, and the middle span length of the equal-height section truss group 1 is 160m, and the length ratio is 1:2.2.

[0123] The height of the equal-height truss group 1 is 9.5 m, and the height of the middle support bracket truss group 2 is 15 m, and the height ratio is 1:1.6.

[0124] The track bridge pier 8 is located at the center position of the upper chord 12 nodes of the equal-height segment truss group. The track bridge pier 8 is welded to the upper chord 12 nodes of the equal-height segment truss group. The number of the track bridge piers 8 is equal to the number of the upper chord 12 nodes of the equal-height segment truss group. The standard spacing between the track bridge piers 8 is 8m.

[0125] The track bridge 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 track bridge pier top cap beam adopts a box section with a width of 5500mm, a height of 1000m~700mm and a wall thickness of 30mm.

[0126] The track beam 9 of the track bridge is installed on the track bridge pier 8 through a support. The span of the track beam 9 is equal to the distance between the nodes of the upper chord rod 12 of the equal-height truss group, and is also equal to the spacing with the upper steel cross beam 18. The standard spacing of the track beam 9 is 8m.

[0127] The track beam 9 adopts a box-type section, the standard transverse spacing of the track beam is 3700mm, the height is 2000mm, and the track structure can be arranged in a three-span one-unit arrangement.

[0128] The suspended ladder beam 10 is arranged on the lower bridge deck system outside the cantilever, and the ladder beam 10 and the lower bridge deck system 4 are connected by welding using a steel hanger 31 .

[0129] The ladder beam 10 has a span of 14 mm, a box-shaped section, a bridge width of 2300 mm, a height of 500 mm, a top plate thickness of 14 mm, a bottom plate width of 1500 mm, a bottom plate thickness of 16 mm, a web plate thickness of 14 mm, and a steel hanger 31 using a GLC650UU steel tie rod with a diameter of 50 mm. The steel hanger 31 is arranged outside the ladder beam 10 at an angle of 79 degrees to the ladder beam 10.

[0130] The suspended corridor bridge 11 is arranged below the lower bridge deck system 4, and the corridor bridge 11 and the lower bridge deck system 4 are connected by welding using steel hangers 31 and rectangular steel pipes.

[0131] The span of the corridor bridge 11 is 37.2mm. The corridor bridge 11 adopts a box section, the bridge width is 4600mm, the height is 800mm, the top plate thickness is 16mm, the bottom plate width is 2800mm, the bottom plate thickness is 20mm, the web thickness is 16mm, and the steel hanger 31 adopts a GLC650UU steel tie rod with a diameter of 60mm. The steel hanger 31 is arranged on the outside or center of the corridor bridge 11, and the angles with the corridor bridge 11 are 130 degrees and 90 degrees respectively. The rectangular steel pipe can provide sufficient longitudinal and lateral rigidity to improve pedestrian comfort. It is arranged on the outside of the corridor bridge 11, and the angles with the corridor bridge 11 are 110 degrees and 90 degrees respectively. The size is 250x250x25mm.

[0132] The suspended ladder beam 10 and the suspended corridor bridge 11 are arranged at the end of the side span of the bridge along the longitudinal direction of the bridge, about 8m away from the theoretical span line of the side span. Two suspended ladder beams 10 and one suspended corridor bridge 11 are arranged in one span, which is convenient for the traffic transfer of people on both sides of the steel truss beam.

[0133] The construction method of a novel multi-layer composite traffic steel truss bridge described in this embodiment is as follows:

[0134] S1. Factory-made steel components including equal-height section equal-height section truss group 1, middle support bracket section truss group 2, upper bridge deck system 3, lower bridge deck system 4, equal-height section struts 5, bracket section struts 6, bracket section transverse connections 7, track bridge piers 8, track beams 9, suspended ladder beams 11, suspended corridor bridges 12, etc.

[0135] S2. Construction of lower foundation and bridge piers;

[0136] S3. Set up temporary piers and temporary trestle, install the support bracket truss group 2 and the bracket section lateral connection 7;

[0137] S4. Use the temporary trestle at the bridge location to install double-sided gantry cranes;

[0138] S5. Using the double-sided gantry crane, connect the middle support bracket truss group 2 and the corresponding position of the equal height segment truss group 1 and the bracket segment support rod 6;

[0139] S6. The main structure of the steel truss is erected by the gantry crane in the following steps: connecting the equal-height truss group 1, the lower deck system 4, the upper deck system 3, and the equal-height support rod 5. To ensure the quality of construction, the gantry crane hoisting components should be the upper chord rod 12 of the main truss of the equal-height truss group and the upper deck system 3, or the lower chord rod 13 of the main truss of the equal-height truss group and the lower deck system 4;

[0140] S7. Hoisting and construction of track bridge pier 8 and track beam 9;

[0141] S8. Welding hanging ladder beam 10, installing ladder beam steel hanger 31;

[0142] S9. Install the suspended corridor bridge 11, the corridor bridge steel hanger 31 and the rectangular steel pipe, and connect the sidewalk expansion joint;

[0143] S10. Carry out bridge deck waterproofing, pavement, guardrails and other ancillary facilities projects.

[0144] Example 2

[0145] like Figures 13 to 18 As shown, the present invention provides a novel multi-layer composite traffic steel truss bridge and a construction method thereof. This embodiment includes a uniform height segment truss group 1, an upper bridge deck system 3, a lower bridge deck system 4, a uniform height segment support rod 5, a track bridge pier 8, a track beam 9, a hanging ladder beam 10 and a hanging corridor bridge 11, as shown in FIG. Figures 13 to 18 shown.

[0146] The novel multi-layer composite traffic steel truss bridge described in this embodiment relies on a provincial first-class highway across the Yellow River. The bridge is designed with a four-layer structure to meet the passage of various three-dimensional traffic functions. Among them, the upper bridge deck system 3 is set with a two-way eight-lane first-class highway, and the design load is highway level I. The lower bridge deck system 4 is set with a two-way four-lane second-class highway in the truss, and the design load is highway level II. Sidewalks are set on both sides of the cantilever of the lower bridge deck system 4. Considering the needs of dense crowds on holidays, the design load is 5kN / m2. The suspended ladder beam 10 and the suspended corridor bridge 11 are set with sidewalks, and the design load is 5kN / m2. The track beam 9 is set with a two-way straddle-type monorail vehicle, and the vehicle design load is a B-type vehicle.

[0147] The bridge span combination described in the embodiment is 75+120+75m, wherein the bridge width of the upper bridge deck system 3 is 43m, and the bridge width of the lower bridge deck system 4 is 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-height struts 5.

[0148] The equi-height segment truss group 1 is divided into two equi-height segment side truss groups 1 and one equi-height segment middle truss group. The equi-height segment middle truss group is located at the center of the bridge, and the equi-height segment side truss groups are symmetrically arranged on both sides of the bridge. The equi-height segment side truss group is composed of two main truss web members 14 connected to the equi-height segment main truss upper chord 12 and the equi-height segment main truss lower chord 13 through node plates, and the equi-height segment middle truss group is composed of two main truss web members 14 connected to the equi-height segment main truss upper chord 12 and the equi-height segment main truss lower chord 13 through node plates. The equi-height segment truss group 1 has a truss height of 10m, and the center distance between the two trusses in the equi-height segment middle truss group is 2.2m. The center distances between the two equi-height segment side truss groups and the equi-height segment middle truss group are both 15.5m.

[0149] The upper chord rod 12 of the main truss of the equal-height segment truss group and the lower chord rod 13 of the main truss of the equal-height segment truss group both adopt box-shaped sections.

[0150] The top plate width of the upper chord 12 of the main truss of the equal-height side truss group is 3500mm, the thickness is 45mm, the bottom plate width is 860mm, the thickness is 45m, the middle distance between the two bottom plates is 2200mm, the web height is 1100mm, the thickness is 45mm, and the center distance between the two webs is 900mm.

[0151] Among them, the top plate width of the upper chord 12 of the main truss of the equal-height section middle truss group is 3500mm, the thickness is 55mm, the bottom plate width is 860mm, the thickness is 55mm, the middle distance between the two bottom plates is 2200mm, the web height is 1100mm, the thickness is 55mm, and the center distance between the two webs is 900mm.

[0152] Among them, the top plate width of the lower chord 13 of the main truss of the equal height section side truss group is 860mm, the thickness is 50mm, the middle distance between the two top plates is 2200mm, the bottom plate width is 3500mm, the thickness is 50mm, the web height is 1100mm, the thickness is 50mm, and the center distance between the two webs is 900mm.

[0153] Among them, the top plate width of the lower chord 13 of the main truss of the equal height section middle truss group is 860mm, the thickness is 58mm, the middle distance between the two top plates is 2200mm, the bottom plate width is 3500mm, the thickness is 58mm, the web height is 1100mm, the thickness is 58mm, and the center distance between the two webs is 900mm.

[0154] The equal-height main truss web members 14 and equal-height support members 5 are all triangular truss structures, the truss node spacing is 8.5m, and each member is symmetrically arranged according to the center line of the bridge;

[0155] The web member 14 of the equal height section main truss adopts a box section with a width of 800mm, a thickness of 40mm, a web thickness of 40mm, and a web member center height of 900mm, which is equal to the web center distance of the upper chord member 12 of the equal height section middle truss group main truss and the lower chord member 13 of the equal height section main truss of the equal height section middle truss group main truss.

[0156] The equal height section support rod 5 adopts a box-shaped rolled steel section of 500x500x25mm.

[0157] The equal-height truss segments 1 are connected by an upper bridge deck system 3 and a lower bridge deck system 4;

[0158] 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-height struts 5;

[0159] The upper bridge deck system 3 includes an upper steel cross beam 18 , an upper steel cross rib 19 , an upper steel longitudinal rib 20 , an upper steel bridge deck 21 and an upper cast-in-place bridge deck 22 .

[0160] The upper steel beam 18 is set at the node position of the upper chord 12 of the equal height section main truss, which is consistent with the number of main truss nodes. The standard spacing of the upper steel beam 18 is 8.5m, which is divided into the upper cantilever steel beam and the upper inter-truss steel beam. The upper steel beam 18 adopts a box section, and the local section of the upper steel beam is set as a variable section. The equal section height of the upper steel beam 18 is equal to the height of the upper chord 12 of the equal height section main truss, which is 1100mm; the upper inter-truss steel beam is set as a fish belly type variable height, the height of the beam at the middle of the span is 1600mm, and the height of the center beam between the trusses is 1.45 times the equal section height of the upper steel beam. The upper cantilever steel beam adopts a linear variable height setting, and the variable section position is from the junction of the beam and the equal height section support rod to the outermost side of the cantilever. The outermost height of the cantilever is 550mm, which is 1 / 2 of the equal section height of the upper steel beam 18. The web thickness of the upper steel beam is 20 mm, the bottom plate width is 500 m, the bottom plate thickness is 30 mm, the top plate thickness is equal to the thickness of the upper steel bridge deck, and the top surface of the upper steel beam 18 is flush with the upper steel bridge deck 21.

[0161] The upper steel transverse rib 19 is transversely arranged between two upper steel beams 18 according to the force requirements of the steel bridge deck 21, and is divided into upper cantilever steel transverse ribs and upper truss steel transverse ribs. The upper steel transverse rib 19 is arranged at a spacing of 2.83m, which is 1 / 3 of the spacing of the upper steel beams. The upper steel transverse rib 19 adopts 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 that of the upper steel bridge deck. The height change of the upper steel transverse rib 19 is equal to that of the corresponding upper steel beam 18. The top surface of the upper steel transverse rib 19 is flush with the upper steel bridge deck 21.

[0162] The upper steel longitudinal ribs 20 are only provided with the upper cantilever steel longitudinal ribs in the longitudinal direction according to the force requirements of the steel bridge deck 21. The upper inter-truss steel longitudinal ribs can be optimized and cancelled according to the calculated strength of the upper steel cross beams and the upper steel cross ribs. The upper steel longitudinal ribs 20 are provided between two upper steel cross beams 18. Two upper cantilever steel longitudinal ribs 20 are provided longitudinally, and the spacing between the upper steel longitudinal ribs 20 is 4m. The upper steel longitudinal ribs 20 adopt an I-shaped 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. The upper steel longitudinal ribs 20 are designed at the same height, which is equal to the height at the corresponding upper steel cross beam 18 position. The top surface of the upper steel longitudinal ribs 20 is flush with the upper steel bridge deck 21.

[0163] The upper steel bridge deck 21 includes a steel flat plate, U-shaped ribs, and plate ribs. The U-shaped rib reinforcement is used in the vehicle driving area of ​​the equal-width section of the bridge deck, and the plate rib reinforcement is used in the vehicle driving area of ​​the variable-width section of the bridge deck. The thickness of the steel flat plate is 24 mm, the wall thickness of the U-shaped rib is 10 mm, the arrangement spacing is 600 mm, the plate rib thickness is 18 mm, the height is 200 mm, and the arrangement spacing is 300 mm.

[0164] 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, 5 cm thick ultra-high performance concrete + 3 cm asphalt concrete is used.

[0165] The lower bridge deck system 4 includes a lower steel cross beam 23 , a lower steel cross rib 24 , a lower steel longitudinal rib 25 , a lower steel bridge deck 26 and a lower cast-in-place bridge deck 27 .

[0166] The lower steel beam 23 is set at the node position of the lower chord 13 of the equal-height main truss, which is consistent with the number of main truss nodes. The standard spacing of the lower steel beam is 8.5m, which is divided into the lower cantilever steel beam and the lower inter-truss steel beam. The lower steel beam 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 beam 23 is designed with a uniform cross section. The uniform cross section height of the lower steel beam 23 is equal to the height of the lower chord 13 of the equal-height main truss, both of which are 1.1m; the top surface of the lower steel beam 23 is flush with the lower steel bridge deck 26.

[0167] The lower steel transverse rib 24 is transversely arranged between two lower steel beams 23 according to the force requirements of the lower steel bridge deck 26, and is divided into lower cantilever steel transverse ribs and lower truss steel transverse ribs. The spacing of the lower steel transverse rib 24 is 2.83m, which is 1 / 3 of the spacing of the lower steel beams 23. The lower steel transverse rib 24 adopts 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 that of the lower steel bridge deck. The lower steel transverse rib 24 is equal in height to the corresponding lower steel beam 23. The top surface of the lower steel transverse rib 24 is flush with the lower steel bridge deck 26.

[0168] The lower steel longitudinal rib 25 is only provided with the lower cantilever steel longitudinal rib in the longitudinal direction according to the force requirement of the lower steel bridge deck 26, and the lower truss steel longitudinal rib can be optimized and cancelled according to the calculated strength of the steel cross beam and steel cross rib. The lower steel longitudinal rib 25 is provided between two lower steel cross beams 23, 2 to 3 lower cantilever steel longitudinal ribs 25 are provided longitudinally, and the arrangement spacing of the lower steel longitudinal rib 25 is 3.5m, and 3 lower truss steel longitudinal ribs 25 are provided longitudinally, and the arrangement spacing of the lower steel longitudinal rib 25 is 4m. The lower steel longitudinal rib 25 adopts an I-shaped 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 lower steel bridge deck. The lower steel longitudinal rib 25 is designed at the same height, and is equal to the height at the corresponding lower steel cross beam 23. The top surface of the lower steel longitudinal rib 25 is flush with the lower steel bridge deck 26.

[0169] The lower steel bridge deck 26 includes a steel bridge deck flat plate, U-shaped ribs, and plate ribs. The U-shaped ribs are used for reinforcement in the vehicle lane of the equal-width section of the bridge deck, and the plate ribs are used for reinforcement in the non-motorized vehicle lane and pedestrian lane. The steel flat plate is 24 mm thick, the U-shaped rib wall is 10 mm thick, and the arrangement spacing is 600 mm. The plate rib is 18 mm thick, 200 mm high, and the arrangement spacing is 300 mm.

[0170] The lower cast-in-place bridge deck 27 is cast on the lower steel bridge deck 26. Since the lower layer adopts highway Class II load, 5cm thick ultra-high performance concrete + 3cm asphalt concrete is used in the carriageway area. 1cm thick modified polyurethane concrete bridge deck can be used in the non-motorized vehicle lane and pedestrian area.

[0171] The upper deck system 3 and the upper chord 12 of the equal-height truss group, and the lower deck system 4 and the lower chord 13 of the equal-height main truss of the equal-height truss group are all connected by welding to form a plate-truss force system combining the deck system and the truss.

[0172] The track bridge pier 8 is located at the center position of the upper chord 12 nodes of the equal-height segment truss group. The track bridge pier 8 is welded to the upper chord 12 nodes of the equal-height segment truss group. The number of the track bridge piers 8 is equal to the number of the upper chord 12 nodes of the equal-height segment truss group. The standard spacing between the track bridge piers 8 is 8.5m.

[0173] The track bridge 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 track bridge pier top cap beam adopts a box section with a width of 5500mm, a height of 1000m~700mm and a wall thickness of 30mm.

[0174] The track beam 9 of the track bridge is installed on the track bridge pier 8 through a support. The span of the track beam 9 is equal to the distance between the nodes of the upper chord rod 12 of the equal-height truss group, and is also equal to the spacing with the upper steel cross beam 18. The standard spacing of the track beam 9 is 8.5m.

[0175] The track beam 9 adopts a box-type section, the standard transverse spacing of the track beam is 4000mm, the height is 2200mm, and the track structure can be arranged in a 4-span one-unit arrangement.

[0176] The suspended ladder beam 10 is arranged on the lower bridge deck system outside the cantilever, and the ladder beam 10 and the lower bridge deck system 4 are connected by welding using a steel hanger 31 .

[0177] The ladder beam 10 has a span of 12m, a box section, a bridge width of 2300mm, a height of 500mm, a top plate thickness of 14mm, a bottom plate width of 1500mm, a bottom plate thickness of 16mm, a web plate thickness of 14mm, and a steel hanger 31 using a GLC460UU steel tie rod with a diameter of 60mm. The steel hanger 31 is arranged outside the ladder beam 10, and the angle with the ladder beam 10 is 79 degrees.

[0178] The suspended corridor bridge 11 is arranged below the lower bridge deck system 4 , and the corridor bridge 11 and the lower bridge deck system 4 are connected by welding using steel hangers 31 .

[0179] The span of the corridor bridge 11 is 40.2 mm, the corridor bridge 11 adopts a box section, the bridge width is 4600 mm, the height is 800 mm, the top plate thickness is 8 mm, the bottom plate width is 2800 mm, the bottom plate thickness is 25 mm, the web thickness is 16 mm, and the steel hanger 31 adopts a GLC460UU steel tie rod with a diameter of 70 mm. The steel hanger 31 is arranged at the outside or center of the corridor bridge 11, and the angles with the corridor bridge 11 are 150 degrees, 130 degrees, and 90 degrees respectively.

[0180] The suspended ladder beam 10 and the suspended corridor bridge 11 are arranged at the end of the side span of the bridge along the longitudinal direction of the bridge, about 10m away from the theoretical span line of the side span. Two suspended ladder beams 10 and one suspended corridor bridge 11 are arranged in each 75m side span to facilitate the traffic transfer of people on both sides of the steel truss beam.

[0181] The construction method of a novel multi-layer composite traffic steel truss bridge described in this embodiment is as follows:

[0182] S1. The factory manufactures steel components such as the contour segment contour segment truss group 1, the upper bridge deck system 3, the lower bridge deck system 4, the contour segment struts 5, the track bridge piers 8, the track beams 9, the suspended ladder beams 11, the suspended corridor bridge 12, etc.

[0183] S2. Construction of lower foundation and bridge piers;

[0184] S3. Set up temporary piers and temporary trestles;

[0185] S4. Use the temporary trestle at the bridge location to install double-sided gantry cranes;

[0186] S5. Use the double-sided gantry cranes to complete the erection of the main structure of the steel truss beam in the following steps: the connection of the equal-height segment truss group 1, the lower deck system 4, the upper deck system 3, and the equal-height segment support rod 5. To ensure the quality of construction, the gantry crane hoisting components should be the upper chord rod 12 of the main truss of the equal-height segment truss group and the upper deck system 3, or the lower chord rod 13 of the main truss of the equal-height segment truss group and the lower deck system 4;

[0187] S6. Hoisting and construction of track bridge pier 8 and track beam 9;

[0188] S7. Welding hanging ladder beam 10, installing ladder beam steel hanger 31;

[0189] S8. Install the suspended corridor bridge 11, the corridor bridge steel hanger 31, and connect the sidewalk expansion joint;

[0190] S9. Carry out bridge deck waterproofing, pavement, guardrails and other ancillary facilities projects.

[0191] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0192] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A new type of multi-layer composite traffic steel truss bridge, characterized by: The multi-layer composite traffic steel truss bridge comprises: a truss group of equal height sections, a truss group of middle support bracket sections, an upper bridge deck system, a lower bridge deck system, equal height section struts, bracket section struts, bracket section transverse connections, track bridge piers, track beams, suspended ladder beams, and suspended gallery bridges; The equal height section truss group and the middle support bracket section truss group are connected either through the lower chord of the equal height section main truss and the upper chord of the middle support bracket truss group, or through the lower chord of the equal height section main truss and the web of the middle support bracket truss group; The equal-height truss segments are connected by an upper bridge deck system and a lower bridge deck system; The middle support bracket section truss groups are connected transversely through the bracket section; The upper bridge deck system on the outer side of the cantilever is connected with the lower bridge deck system by supporting rods of equal height sections; The lower deck system on the outer side of the cantilever is connected to the bracket section truss group at the middle support point through the bracket section brace support; The track bridge piers are connected to the equal-height section truss groups; The track beam is installed on the track bridge pier through a support; The suspended ladder beam is arranged below the lower bridge deck system and connected to the lower bridge deck system via a steel hanger or a vertical structure; The suspended corridor bridge is arranged below the lower bridge deck system and connected to the lower bridge deck system via a steel hanger or a vertical structure; The suspended stairway beam and the suspended corridor bridge are connected through a sidewalk expansion joint.

2. The novel multi-layer composite traffic steel truss bridge according to claim 1 is characterized by: The equal height segment truss piece group is formed by connecting the equal height segment main truss upper chord and the equal height segment main truss lower chord through a node plate with a single or multiple equal height segment main truss web members; Wherein, the upper chord of the equal-height main truss and the lower chord of the equal-height main truss both adopt box-shaped, open π-shaped or semi-open π-shaped cross-sections; The web members of the main trusses of equal height sections adopt a triangular truss structure, are arranged symmetrically according to the center line of the bridge, and adopt a box-type or I-shaped section.

3. The novel multi-layer composite traffic steel truss bridge according to claim 1 is characterized by: The middle support bracket segment truss piece group is formed by connecting a single or multiple middle support bracket segment main truss web bars to the middle support bracket segment main truss upper chord bar and the middle support bracket segment main truss lower chord bar through node plates; Among them, the upper chord of the main truss of the middle support bracket section and the lower chord of the main truss of the middle support bracket section both adopt box-type, open π-type or semi-open π-type sections; Among them, the main truss web of the center support bracket section adopts a triangular truss structure, is arranged symmetrically according to the center line of the bridge, and adopts a box-type or I-shaped section.

4. The novel multi-layer composite traffic steel truss bridge according to claim 1 is characterized in that: The upper bridge deck system includes an upper steel cross beam, an upper steel cross rib, an upper steel longitudinal rib, an upper steel bridge deck and an upper cast-in-place bridge deck; Among them, the upper steel cross beam is arranged at the node position of the upper chord of the main truss of the same height section, the upper steel transverse rib is arranged horizontally between the upper steel cross beams, the upper steel longitudinal rib is arranged longitudinally between the upper steel cross beams, the upper steel bridge deck is laid on the upper steel cross beams, and the upper cast-in-place bridge deck is cast on the upper steel bridge deck.

5. The novel multi-layer composite traffic steel truss bridge according to claim 1 is characterized by: The lower deck system includes lower steel cross beams, lower steel cross ribs, lower steel longitudinal ribs, lower steel bridge deck and lower cast-in-place bridge deck; Among them, the lower steel cross beam is arranged at the node position of the lower chord of the main truss of the same height section, the lower steel transverse rib is arranged horizontally between the two lower steel cross beams, the lower steel longitudinal rib is arranged longitudinally between the two lower steel cross beams, the lower steel bridge deck is laid on the lower steel cross beams, and the lower cast-in-place bridge deck is cast on the lower steel bridge deck.

6. The novel multi-layer composite traffic steel truss bridge according to claim 1 is characterized by: The equal height section braces and bracket section braces adopt a triangular truss structure, and the equal height section braces and bracket section braces adopt a circular, box-shaped or I-shaped cross section; The bracket section transverse connection is composed of a bracket upper cross brace and a bracket lower cross brace, which are respectively welded to the bracket section truss group at the middle support point to form a stable spatial force system; Among them, the lower cross brace of the bracket is arranged at the node position of the lower chord of the main truss of the middle support bracket section, and the number of the lower cross braces of the bracket is equal to the number of the lower chord nodes of the main truss of the middle support bracket section.

7. The novel multi-layer composite traffic steel truss bridge according to claim 1 is characterized by: The track bridge piers and the center positions of the upper chord nodes of the equal-height segment truss groups are connected by welding. The number of track bridge piers is consistent with the number of upper chord nodes of the equal-height segment truss groups, and the span of the track beam is equal to the distance between the upper chord nodes of the equal-height segment truss groups.

8. A novel multi-layer composite traffic steel truss bridge according to claim 3 or 6, characterized in that: The line shape of the lower chord of the main truss of the middle support bracket section is a broken line or a multiple parabola. The lower chord of the main truss of the middle support bracket section is filled with middle support ultra-high performance concrete to form a steel-concrete composite lower chord. The ratio of the filling height of the middle support ultra-high performance concrete to the web height of the lower chord of the main truss of the middle support bracket section is 1:1 to 1:

5.

9. A novel multi-layer composite traffic steel truss bridge according to any one of claims 1 to 8, characterized in that: The ratio of the length of one side of the middle support bracket truss group to the middle span length of the middle support bracket truss group is 1:3 to 1:8; The ratio of the height of the equal-height section truss piece group to the middle support bracket truss piece group is 1:0.5 to 1:

4.

10. A construction method for a novel multi-layer composite traffic steel truss bridge according to any one of claims 1 to 8, characterized in that: include: S1. Factory-made equal-height section equal-height section truss group, middle support bracket section truss group, upper deck system, lower deck system, equal-height section struts, bracket section struts, bracket section transverse connections, track bridge piers, track beams, suspended ladder beams, and suspended gallery bridges; S2. Construction of lower foundation and bridge piers; S3. Erect temporary piers and temporary trestles, and install the fulcrum bracket truss group and the horizontal connection of the bracket section; S4. Use the temporary trestle at the bridge location to install double-sided gantry cranes; S5. Use the double-sided gantry crane to connect the middle support bracket truss group and the corresponding equal-height segment truss group and bracket segment support rod; S6. The main structure of the steel truss is erected by connecting the equal-height segment truss group, the lower deck system, the upper deck system, and the equal-height segment struts in sequence through a gantry crane; the gantry crane hoisting assembly is an integral component of the upper chord of the main truss of the equal-height segment truss group and the upper deck system or an integral component of the lower chord of the main truss of the equal-height segment truss group and the lower deck system; S7. Lifting and construction of bridge piers and rail beams of rail bridge; S8. Welding of hanging ladder beams, installation of ladder beam steel hangers or vertical structures; S9. Install suspended corridor bridges, corridor bridge steel hangers or vertical structures to connect pedestrian expansion joints; S10. Carry out bridge deck waterproofing, pavement, guardrails and ancillary facilities engineering.

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