Main girder structure of a double-deck four-track railway steel truss girder cable-stayed bridge

Abstract

The present invention relates to a main girder structure of a double-deck four-track railway steel truss cable-stayed bridge. Through double-deck arrangement, two railways are provided on each layer, which can reduce the lateral span of the steel truss girder, so that only two main trusses on both sides are required. And cross braces are connected between the tops of the corresponding two web members of the two main trusses on both sides, enabling the upper deck system to be stably supported by the two main trusses and the top cross braces. Moreover, the first deck system and the third deck system in the non-ballast sections of the mid-span and side spans of the bridge adopt orthotropic plates, and the second deck system and / or the fourth deck system in the ballast sections of the side spans of the bridge adopt a combined cross-section form of a steel box, ballast bodies inside the steel box and a steel bridge deck, solving the ballast problem in the ballast area. Furthermore, the railway lines can be evenly arranged on the upper and lower layers, the truss width of the steel truss girder can be reduced, the cross-section of the steel truss girder can be fully utilized, the steel consumption can be greatly reduced, and the difficulty of the diversion project on both banks of the bridge can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of double - layer four - line railway steel truss girders, and particularly to a main girder structure of a cable - stayed bridge with double - layer four - line railway steel truss girders. Background Art

[0002] In recent years, the railway industry in China has developed rapidly, and there are an increasing number of large - span bridges spanning large rivers and high - level navigable rivers. Building too many bridges across large rivers will have an adverse impact on the coastal ecology, landscape and overall planning. For the purpose of saving river - crossing channel resources, multi - line railways are usually planned to be constructed using the same river - crossing channel.

[0003] At present, the layout forms of four - line railway steel truss girders at home and abroad mainly adopt the arrangement of four - line railways on the same layer, such as the Anqing Yangtze River Bridge of the Ning'an Railway, the Jiaojiang Extra - large Bridge of the Hangzhou - Shaoxing - Taizhou Railway, and the Dongxin Ganjiang Extra - large Bridge of the Nanchang Hub. When four - line railways are arranged on the same layer, if steel truss girders are used, the truss width will be relatively wide, and some bridges adopt the layout form of three main trusses, resulting in a large amount of steel consumption; if steel box girders are used, the overall vertical stiffness is slightly less than that of steel truss girders. In some cases, the same - layer arrangement brings certain difficulties to the bridge - approach engineering on both sides of the bridge. Different railway lines need to detour, increasing the difficulty of approach; there are situations where freight railways and passenger dedicated lines run in parallel, reducing the approach efficiency on both sides of the bridge and increasing the engineering complexity. When the steel truss girder is connected to the tunnel, the diameter of the four - line railway flat - layer tunnel is too large, and the construction risk increases sharply. Summary of the Invention

[0004] The purpose of the present invention is to provide a main girder structure of a cable - stayed bridge with double - layer four - line railway steel truss girders to solve the problems existing in the prior art that when four - line railway steel truss girders spanning large rivers are arranged on the same layer, the truss width is relatively wide, the steel consumption is large, and it brings certain difficulties to the bridge - approach engineering on both sides of the bridge.

[0005] In order to achieve the above - mentioned purpose, the technical solution adopted by the present invention is as follows:

[0006] A main girder structure of a cable - stayed bridge with double - layer four - line railway steel truss girders, comprising main trusses located on both lateral sides of the bridge. The main trusses include upper chord bars, lower chord bars and a plurality of vertically arranged web members. The upper chord bars and the lower chord bars are both arranged along the longitudinal bridge direction. The upper ends of the web members are connected to the upper chord bars, and the lower ends are connected to the lower chord bars. All the web members are arranged at intervals along the longitudinal bridge direction;

[0007] A lower bridge deck system is connected between the two lower chord bars of the two main trusses, and an upper bridge deck system is connected between the two upper chord bars of the two main trusses. Two railways are respectively arranged above the lower bridge deck system and above the upper bridge deck system. The two railways above the upper bridge deck system are correspondingly arranged directly above the two railways above the lower bridge deck system. Bridge deck cross beams are arranged at intervals along the longitudinal bridge direction of the upper bridge deck system and the lower bridge deck system. The two ends of the bridge deck cross beam are correspondingly connected to the upper chord bar or the lower chord bar of the two main trusses on both sides;

[0008] A cross bracing is connected between the tops of the corresponding two web members on both sides of the two main trusses. The upper side of the cross bracing is connected to the lower side of the upper bridge deck system;

[0009] The upper bridge deck system is divided into a first bridge deck system and a second bridge deck system along the longitudinal bridge direction. The first bridge deck system corresponds to the non-ballast sections of the mid-span and side spans of the bridge, and the second bridge deck system corresponds to the ballast sections of the side spans of the bridge. The lower bridge deck system is divided into a third bridge deck system and a fourth bridge deck system along the longitudinal bridge direction. The third bridge deck system corresponds to the non-ballast sections of the mid-span and side spans of the bridge, and the fourth bridge deck system corresponds to the ballast sections of the side spans of the bridge. The first bridge deck system and the third bridge deck system are both orthotropic plates, and the top surface of the orthotropic plate is used to arrange the railway; the second bridge deck system and / or the fourth bridge deck system includes a steel box, a steel bridge deck on the top of the steel box, and a ballast body filled in the steel box. The steel bridge deck is used to arrange the railway.

[0010] For the main girder structure of the double-deck four-track railway steel truss cable-stayed bridge adopting this scheme, through the double-deck arrangement, with two railways arranged on each layer, the transverse span of the steel truss can be reduced, so that only the two main trusses on both sides are needed. And by connecting a cross bracing between the tops of the corresponding two web members on both sides of the two main trusses, that is, by connecting cross bracings between the tops of the web members on the transverse two sides of the steel truss, the upper bridge deck system can be stably supported by the two main trusses and the top cross bracing; moreover, the first bridge deck system and the third bridge deck system corresponding to the non-ballast sections of the mid-span and side spans of the bridge adopt orthotropic plates, with light structural construction, and the bridge deck can transfer longitudinal forces as a whole and share the axial force pressure of the main truss; the second bridge deck system and / or the fourth bridge deck system corresponding to the ballast sections of the side spans of the bridge adopt a combined cross-section form of a steel box, a ballast body in the steel box and a steel bridge deck. On the basis of solving the ballast problem in the ballast area, the steel consumption is reduced, and at the same time, the problem of the force of the concrete slab in the negative moment area at the auxiliary pier can be effectively solved; furthermore, the railway lines can be evenly arranged on the upper and lower layers, instead of being like the double-deck six-track structure where only four tracks can be arranged on the upper layer and two tracks on the lower layer and cannot be evenly arranged. This double-deck four-track arrangement method can reduce the truss width of the steel truss compared with the single-deck four-track structure form, make full use of the cross-section of the steel truss, greatly reduce the steel consumption, and can also reduce the difficulty of the diversion project on both sides of the bridge.

[0011] Preferably, the steel box is composed of a bottom plate, side plates on both lateral sides of the bridge, and two adjacent cross beams of the bridge deck system. The bottom plate and the side plates are both arranged between two adjacent cross beams of the bridge deck system. The bottom plate, the two side plates, the two cross beams of the bridge deck system, and the steel bridge deck enclose a closed box structure, and the ballast is filled in the closed box structure.

[0012] In this solution, a closed box structure is formed by the bottom plate, the two side plates, two corresponding adjacent cross beams of the bridge deck system, and the steel bridge deck of the steel truss beam, so that the space between two adjacent cross beams of the bridge deck system can be filled with ballast materials, enabling the ballast area structure to be combined with the steel truss beam to achieve the ballast function. The ballast can be formed by pouring ballast materials such as concrete and mortar in the prior art; the unit weight of the ballast and the closed box structure are designed according to the actual construction conditions, and the bottom plate and the side plates are designed according to the actual construction conditions.

[0013] In this solution, the bottom plate and the two side plates are both supported by the cross beams of the bridge deck system, so there is no need to separately set up small longitudinal beams for support; moreover, the closed box structure is a large and closed ballast box, which is formed by means of the bridge deck system and the steel bridge deck of the steel truss beam, simplifying the connection structure between the ballast area and the steel truss beam; and the bridge deck system and the steel bridge deck of the steel truss beam are not only the bridge structure but also part of the ballast box of the ballast, with high steel utilization rate; and the overall volume of the closed box structure is larger than that of the ballast box between two adjacent cross beams of the bridge deck system in the prior art, which can reduce the unit weight of the ballast materials, thereby reducing costs, and there is no need to increase the ballast like the prior art by increasing the height of the cross beam of the bridge deck system or significantly increasing the height of the cross beam of the bridge deck system; the above reasons result in less steel consumption in the ballast area. And because there is no need to set up small longitudinal beams, only the bottom plate and the side plates need to be installed between two adjacent cross beams of the bridge deck system, with a larger construction space, fewer construction steps, and simpler construction; the bottom plate and the side plates can be installed in a timely manner after installing two adjacent cross beams of the bridge deck system, which can improve the installation efficiency. After the closed box structure is filled with ballast materials, the ballast materials can directly support the steel bridge deck, effectively improving the fatigue characteristics of the steel bridge deck, so that neither the steel bridge deck nor the bridge deck system below at the closed box structure needs post-maintenance, and the entire ballast area also does not need maintenance.

[0014] Further preferably, the lower part of the ballast is a normal concrete layer and the upper part is a self-compacting cement mortar layer.

[0015] In this solution, by adopting a closed box structure, the total volume of all ballast boxes between two adjacent bridge deck system crossbeams is larger than that of the prior art. Under the condition of ensuring the same ballast weight, ordinary concrete and self-compacting cement mortar with a smaller unit weight than heavy concrete can be used to achieve ballast. The ordinary concrete layer at the lower part inside the closed box structure has strong bearing capacity, and the self-compacting cement mortar layer is beneficial to filling the upper part of the closed box structure, while ensuring safety and compactness. Compared with heavy concrete, filling the internal space of the closed box structure with the ordinary concrete layer and the self-compacting cement mortar layer is simpler in construction, and the cost of the materials themselves is also lower, thus saving construction costs.

[0016] Preferably, the steel box of the second bridge deck system is composed of a bottom plate, upper chord bars on both lateral sides of the bridge, and two adjacent bridge deck system crossbeams. The bottom plate is arranged between two adjacent bridge deck system crossbeams. The bottom plate, the upper chord bars on both sides, the two bridge deck system crossbeams, and the steel bridge deck enclose a closed box structure, and the ballast body is filled in the closed box structure;

[0017] The steel box of the fourth bridge deck system is composed of a bottom plate, lower chord bars on both lateral sides of the bridge, and two adjacent bridge deck system crossbeams. The bottom plate is arranged between two adjacent bridge deck system crossbeams. The bottom plate, the lower chord bars on both sides, the two bridge deck system crossbeams, and the steel bridge deck enclose a closed box structure, and the ballast body is filled in the closed box structure.

[0018] In this solution, there is no need to separately set side plates. The upper chord bars can be used as side plates to enclose the closed box structure of the second bridge deck system, and the lower chord bars can be used as side plates to enclose the closed box structure of the fourth bridge deck system. Through this setting method, side plates can be not set, making the installation of the closed box structure convenient, and enabling the fourth bridge deck system and the second bridge deck system to directly form an integral body with the corresponding chord bars, with higher stability and better force transmission; and the closed box structure can be widened, increasing the volume of the ballast body that can be set, and enhancing the ballast capacity.

[0019] Further preferably, the steel box is only provided in the fourth bridge deck system;

[0020] Or,

[0021] The steel box is provided in both the fourth bridge deck system and the second bridge deck system, and the volume of the steel box of the fourth bridge deck system is larger than that of the steel box of the second bridge deck system.

[0022] Because the ballast capacity is enhanced, when the ballast that can meet the double - layer steel truss girder can be set only in the fourth bridge deck system, the steel box may not be set at the bottom of the second bridge deck system on the upper layer. If the ballast set only in the fourth bridge deck system cannot meet the ballast requirements of the double - layer steel truss girder, large ballast is preferentially set in the fourth bridge deck system and small ballast is set in the second bridge deck system, that is, the volume of the steel box in the fourth bridge deck system is larger than that of the steel box in the second bridge deck system. This setting method enables all steel boxes or larger steel boxes to be constructed on the lower layer as much as possible, making the construction more convenient. At the same time, it can avoid or reduce the influence of the upper ballast on the lower bridge deck system and its lines by minimizing the ballast body on the upper layer or reducing the volume of the ballast body on the upper layer.

[0023] Preferably, the ballast body includes at least two layers of shrinkage - compensating concrete layers filled in a layered manner, which can ensure that the ballast body is filled densely and can prevent concrete shrinkage, so as to avoid the separation of the ballast body from the closed box - type structure and ensure the integrity of the bridge deck system.

[0024] Preferably, a number of first stiffening ribs are distributed at intervals along the transverse bridge direction at the bottom of the steel bridge deck, and the first stiffening ribs are arranged along the longitudinal bridge direction; through the first stiffening ribs, the ballast body and the steel bridge deck can be better combined together;

[0025] When the lower part of the ballast body is a normal concrete layer, the top surface height of the normal concrete layer is not higher than the bottom of the first stiffening rib of the steel bridge deck. The actual height of the normal concrete layer is determined according to the specific ballast weight, but the top surface height of the normal concrete layer should not be higher than the bottom of the first stiffening rib of the steel bridge deck, so that the corners such as the first stiffening ribs of the steel bridge deck can be better filled with self - compacting mortar, improving the filling effect inside the closed box - type structure.

[0026] Preferably, a number of second stiffening ribs are provided above the bottom plate, and the second stiffening ribs are arranged along the longitudinal bridge direction. At the corner of the web and the lower flange of the cross - beam of the bridge deck system, a joint plate is vertically arranged along the longitudinal bridge direction, and the second stiffening rib is connected to the corresponding joint plate of the cross - beam of the bridge deck system by a first high - strength bolt;

[0027] and / or;

[0028] A number of shear studs are provided on all four sides of the closed box - type structure.

[0029] The gusset plate is vertically arranged at the corner of the web and the lower flange of the cross beam of the bridge deck system. A second stiffening rib is arranged on the top surface of the bottom plate along the longitudinal direction of the bridge and corresponding to the position of the gusset plate. While ensuring sufficient strengthening of the bottom plate, it can also more stably connect the bottom plate and the cross beam of the bridge deck system through the first high-strength bolts. Moreover, the gusset plate can make the combination effect of the ballast body and the cross beam of the bridge deck system better, and the second stiffening rib can make the combination effect of the ballast body and the bottom plate better. In this way, not only can the cross beam and the bottom plate of the bridge deck system be strengthened, but also the combination performance of the ballast body and the steel box can be strengthened, making the overall ballast capacity of the bridge deck system in the entire ballast area stronger, with greater stiffness and excellent train running performance.

[0030] Preferably, both sides of the cross bracing in the transverse direction of the bridge are bolted to the corresponding web members, and the upper side of the cross bracing is welded to the lower side of the upper bridge deck system, which avoids the impact of the bolt drop of the upper bridge deck system on the safety of the lower railway and ensures the installation convenience.

[0031] Preferably, the cross bracing includes a cross bar and several diagonal bars. The upper ends of the diagonal bars are connected to the upper side of the cross bar, and the lower ends are connected to the lower side of the upper bridge deck system. The cross bar, the upper bridge deck system and all the diagonal bars together form several equilateral triangle structures arranged continuously along the transverse direction of the bridge. While reducing the members, it can be combined with the upper bridge deck system to improve the support effect on the upper bridge deck system.

[0032] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are:

[0033] 1. The main girder structure of the double - layer four - track railway steel truss girder cable - stayed bridge of the present invention, through double - layer arrangement with two railways set on each layer, can reduce the lateral span of the steel truss girder, so that only the two main trusses on both sides are needed. And by connecting cross - braces between the tops of the corresponding two web members of the two main trusses on both sides, that is, by connecting cross - braces between the tops of the web members on both lateral sides of the steel truss girder, the upper deck system can be stably supported by the two main trusses on both sides and the top cross - braces. And for the first deck system and the third deck system in the non - ballast sections of the mid - span and side - span of the bridge, orthotropic plates are adopted, with light structural construction. The deck can transfer longitudinal forces as a whole and share the axial force pressure of the main truss. For the second deck system and / or the fourth deck system in the ballast section of the side - span of the bridge, a combined cross - section form of steel box, ballast body inside the steel box and steel bridge deck is adopted, which solves the ballast problem that the single - layer four - track ballast structure is not applicable to the ballast area of the double - layer four - track, reduces the steel consumption, and can effectively solve the problem of the force on the concrete slab in the negative moment area at the auxiliary pier. Furthermore, the railway lines can be evenly arranged on the upper and lower layers, unlike the double - layer six - track where only four lines can be set on the upper layer and two lines on the lower layer and cannot be evenly arranged. This double - layer four - track setting method, compared with the single - layer four - track structural form, can reduce the truss width of the steel truss girder, make full use of the cross - section of the steel truss girder, greatly reduce the steel consumption, and can reduce railway detours, realize passenger - freight separation, and reduce the difficulty of the relief project on both sides of the bridge.

[0034] 2. The second deck system and / or the fourth deck system located in the ballast area adopt an integral cross - section form of a closed box - type structure and a ballast body, so that the ballast structure is combined with the force - bearing structure, making the ballast capacity in the ballast area stronger, the structure simple, the material consumption less, the construction convenient, the cost low, and can effectively improve the fatigue characteristics of the steel bridge deck, so that neither the steel bridge deck nor the lower deck system at the closed box - type structure needs post - maintenance, and the entire ballast area does not need maintenance.

[0035] 3. The closed box - type structure of the second deck system can be formed by using the upper chord as the side plate, and the closed box - type structure of the fourth deck system can be formed by using the lower chord as the side plate. Through this setting method, no side plates need to be set, making the installation of the closed box - type structure convenient, and enabling the fourth deck system and the second deck system to be directly integrated with the corresponding chord members, with higher stability and better force transmission. And the closed box - type structure can be widened, increasing the volume of the ballast body that can be set, and enhancing the ballast capacity.

[0036] 4. Adopt a cross - brace structure with full - welding on the top surface and bolt - connection on the side surface to the web member, which avoids the impact of the bolt dropping of the upper deck system on the safety of the lower - layer railway and ensures the installation convenience.

[0037] 5. Compared with the flat - layer four - track structure and the all - steel deck truss girder structure, it has great stiffness and excellent train running performance. Brief Description of the Drawings

[0038] Figure 1 It is a cross-sectional view of the non-ballast section of the mid-span and side-span of the main girder structure of the double-deck four-track railway steel truss girder cable-stayed bridge described in the present invention;

[0039] Figure 2 It is a cross-sectional view of the ballast section of the side-span of the main girder structure of the double-deck four-track railway steel truss girder cable-stayed bridge described in Embodiment 1;

[0040] Figure 3 is Figure 2 A cross-sectional view of the fourth deck system in

[0041] Figure 4 It is a cross-sectional view of the upper deck system or the lower deck system of the ballast area of the side-span in Embodiment 2;

[0042] Figure 5 is Figure 4 The sectional view at A-A in

[0043] Figure 6 is Figure 4 The sectional view at B-B in

[0044] Figure 7 It is a plan structure diagram of the upper deck system or the lower deck system of the ballast area of the side-span in Embodiment 2.

[0045] Icon: 1 - upper chord; 2 - lower chord; 3 - web member; 41 - first deck system; 42 - second deck system; 51 - third deck system; 52 - fourth deck system; 6 - cross bracing; 7 - railway; 81 - first high-strength bolt; 82 - second high-strength bolt; 9 - side plate; 91 - manhole; 10 - steel bridge deck; 11 - bottom plate; 12 - first stiffening rib; 13 - second stiffening rib; 131 - third stiffening rib; 14 - deck system cross beam; 151 - ordinary concrete layer; 152 - self-compacting cement mortar layer; 153 - shrinkage-compensating concrete layer; 1511 - first layer; 1512 - second layer; 16 - shear stud; 17 - joint plate; 18 - bridge deck longitudinal beam. Detailed implementation manners

[0046] The present invention will be described in detail below with reference to the accompanying drawings.

[0047] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0048] Embodiment 1

[0049] This embodiment provides a main girder structure of a double-deck four-track railway steel truss girder cable-stayed bridge. Refer toFigures 1 - 3 , showing the transverse direction of the bridge, including main trusses located on both sides of the bridge in the transverse direction. The main trusses include upper chord members 1, lower chord members 2, and several vertically arranged web members 3. Both the upper chord members 1 and the lower chord members 2 are arranged along the longitudinal direction of the bridge. The upper ends of the web members 3 are connected to the upper chord members 1, and the lower ends are connected to the lower chord members 2. All the web members 3 are arranged at intervals along the longitudinal direction of the bridge;

[0050] A lower bridge deck system is connected between the two lower chord members 2 of the two main trusses, and an upper bridge deck system is connected between the two upper chord members 1 of the two main trusses. Two railways 7 are respectively arranged above the lower bridge deck system and above the upper bridge deck system. The two railways 7 above the upper bridge deck system are correspondingly arranged directly above the two railways 7 above the lower bridge deck system. The longitudinal directions of the upper bridge deck system and the lower bridge deck system are both provided with bridge deck cross beams 14 at intervals. The two ends of the bridge deck cross beams 14 are correspondingly connected to the upper chord members 1 or the lower chord members 2 of the two main trusses on both sides;

[0051] Cross bracings 6 are connected between the tops of the corresponding two web members 3 of the two main trusses on both sides. The upper side of the cross bracings 6 is connected to the lower side of the upper bridge deck system;

[0052] As Figures 1 - 2 shown, the upper bridge deck system is divided into a first bridge deck system 41 and a second bridge deck system 42 along the longitudinal direction of the bridge. The first bridge deck system 41 corresponds to the non-ballast sections of the mid-span and side spans of the bridge. The second bridge deck system 42 corresponds to the ballast sections of the side spans of the bridge. The lower bridge deck system is divided into a third bridge deck system 51 and a fourth bridge deck system 52 along the longitudinal direction of the bridge. The third bridge deck system 51 corresponds to the non-ballast sections of the mid-span and side spans of the bridge. The fourth bridge deck system 52 corresponds to the ballast sections of the side spans of the bridge. Both the first bridge deck system 41 and the third bridge deck system 51 are orthotropic plates, and the top surfaces of the orthotropic plates are used to arrange the railways 7; The second bridge deck system 42 and / or the fourth bridge deck system 52 includes a steel box, a steel bridge deck 10 on the top of the steel box, and a ballast body filled in the steel box. The steel bridge deck 10 is used to arrange the railways 7.

[0053] For the main girder structure of the double-deck four-track railway steel truss cable-stayed bridge adopting this solution, as Figure 1As shown, by arranging in upper and lower double layers, with two railways 7 provided in each layer and the upper and lower railways 7 arranged correspondingly, the lateral span of the steel truss girder can be reduced, such that only the main trusses on both sides need to be provided. And by connecting cross braces 6 between the tops of the corresponding two web members 3 of the main trusses on both sides, and connecting the upper part of the cross braces 6 to the bottom of the upper deck system, that is, by connecting cross braces 6 between the tops of the web members 3 on the lateral two sides of the steel truss girder, it is enabled to integrate the upper deck system with the main trusses on both sides and the top cross braces 6 into one body and stably support the upper deck system. And for the first deck system 41 and the third deck system 51 in the non-ballast sections of the mid-span and side spans of the bridge, orthotropic plates are adopted, as Figure 1 shown, the structural construction is light, the deck can transfer longitudinal forces integrally and share the axial force pressure of the main truss. For the second deck system 42 in the ballast section of the side span of the bridge and / or the fourth deck system 52, a combined cross-section form of a steel box, ballast bodies inside the steel box and a steel bridge deck 10 is adopted, as Figure 2 shown. On the basis of solving the ballast problem in the ballast area, the steel consumption is reduced, and at the same time, the problem of the force-bearing of the concrete slab in the negative moment area at the auxiliary pier can be effectively solved. Furthermore, the railway lines can be evenly arranged in the upper and lower layers, instead of only being able to arrange four lines in the upper layer and two lines in the lower layer like the double-layer six-line structure, which cannot be evenly arranged due to force-bearing problems. This double-layer four-line arrangement method can reduce the truss width of the steel truss girder compared with the single-layer four-line structural form, make full use of the cross-section of the steel truss girder, greatly reduce the steel consumption, and can also reduce the difficulty of the diversion project on both banks of the bridge.

[0054] Among them, Figure 2 the cross-section of the ballast area shown, Figure 2Both the upper bridge deck system and the lower bridge deck system adopt the form of arranging steel boxes and ballast bodies. Of course, according to the actual situation, if the form of arranging steel boxes and ballast bodies in the lower layer can meet the ballast requirements of the double layer, there is no need to arrange the form of steel boxes and ballast bodies in the upper layer. Similarly, it is possible to set only the upper bridge deck system as the cross-sectional form with ballast bodies, or only set the lower bridge deck system as the cross-sectional form with ballast bodies. If the cross-sectional form with ballast bodies arranged in a single layer cannot meet the ballast requirements of the double layer, it is necessary to set both the upper bridge deck system and the lower bridge deck system as the cross-sectional form with ballast bodies. As a preferred implementation method, the steel box is only provided in the fourth bridge deck system 52; or, the steel box is provided in both the fourth bridge deck system 52 and the second bridge deck system 42, and the volume of the steel box in the fourth bridge deck system 52 is larger than the volume of the steel box in the second bridge deck system 42. Because the ballast capacity is enhanced, when only setting in the fourth bridge deck system 52 can meet the ballast requirements of the double-layer steel truss beam, it is not necessary to set a steel box at the bottom of the second bridge deck system 42 in the upper layer. If only setting in the fourth bridge deck system 52 cannot meet the ballast requirements of the double-layer steel truss beam, large ballast is preferentially set in the fourth bridge deck system 52 and small ballast is set in the second bridge deck system 42, that is, the volume of the steel box in the fourth bridge deck system 52 is larger than the volume of the steel box in the second bridge deck system 42. This setting method enables all steel boxes or larger steel boxes to be constructed in the lower layer as much as possible, making the construction more convenient. At the same time, it is possible to avoid or reduce the influence of the upper ballast body on the lower bridge deck system and its lines by not setting ballast bodies in the upper layer or reducing the volume of the ballast bodies set in the upper layer as much as possible.

[0055] As Figures 2 - 3 shown, the steel box of the second bridge deck system 42 is composed of a bottom plate 11, upper chord bars 1 on both sides of the bridge in the transverse direction, and two adjacent bridge deck cross beams 14. The bridge deck cross beam 14 can refer to the Figure 5 structural form therein. Among them, Figure 1 both the first bridge deck system 41 and the third bridge deck system 51 in the Figure 2 are provided with bridge deck cross beams 14 along the longitudinal direction of the bridge. The spacing between the bridge deck cross beams 14 of the first bridge deck system 41 and the third bridge deck system 51 is 2.5 - 4 m, ensuring the strength of the orthotropic plates of the first bridge deck system 41 and the third bridge deck system 51;

[0056] The steel box of the fourth bridge deck system 52 is composed of a bottom plate 11, lower chord members 2 on both lateral sides of the bridge, and two adjacent bridge deck cross beams 14. The bottom plate 11 is arranged between two adjacent bridge deck cross beams 14. The bottom plate 11, the lower chord members 2 on both sides, the two bridge deck cross beams 14, and the steel bridge deck 10 enclose a closed box structure, and the ballast is filled in the closed box structure.

[0057] In this embodiment, there is no need to separately arrange side plates 9. By using the upper chord member 1 as the side plate 9, a closed box structure of the second bridge deck system 42 can be enclosed. By using the lower chord member 2 as the side plate 9, a closed box structure of the fourth bridge deck system 52 can be enclosed. Through this setting method, it is possible not to set side plates 9, making the installation of the closed box structure convenient, and enabling the fourth bridge deck system 52 and the second bridge deck system 42 to be directly integrated with the corresponding chord members, with higher stability and better force transmission. Moreover, it is possible to widen the closed box structure, increase the volume of the ballast that can be set, and enhance the ballast capacity.

[0058] In this embodiment, the ballast includes at least two layers of shrinkage compensation concrete layers 153 filled in a layered manner. It can ensure that the ballast is filled densely and can prevent the shrinkage of concrete, so as to avoid the separation of the ballast from the closed box structure and ensure the integrity of the bridge deck system.

[0059] As Figure 3 shown, a number of first stiffening ribs 12 are distributed at intervals along the transverse direction of the bridge at the bottom of the steel bridge deck 10, and the first stiffening ribs 12 are arranged along the longitudinal direction of the bridge. Through the first stiffening ribs 12, the ballast and the steel bridge deck 10 can be better combined, and at the same time, the steel bridge deck 10 can be strengthened. The first stiffening ribs 12 can adopt the form of U ribs.

[0060] Optionally, a number of second stiffening ribs 13 are provided above the bottom plate 11, and the second stiffening ribs 13 are arranged along the longitudinal direction of the bridge. The second stiffening ribs 13 can strengthen the bottom plate 11, so that the thickness of the bottom plate 11 can be reduced, thereby reducing the use of steel. Moreover, the second stiffening ribs 13 can make the combination effect of the ballast and the bottom plate 11 better. In this embodiment, at the corner of the web and the lower flange of the bridge deck cross beam 14, a gusset plate 17 is vertically arranged along the longitudinal direction of the bridge. For reference, see Figure 5 The second stiffening rib 13 and the corresponding gusset plate 17 of the bridge deck cross beam 14 are connected by first high-strength bolts 81; the gusset plate 17 is vertically arranged at the corner of the web and the lower flange of the bridge deck cross beam 14, and the second stiffening rib 13 is arranged on the top surface of the bottom plate 11 along the longitudinal direction corresponding to the position of the gusset plate 17. While ensuring sufficient strengthening of the bottom plate 11, the bottom plate 11 and the bridge deck cross beam 14 can be more stably connected through the first high-strength bolts 81. And the gusset plate 17 can make the combination effect of the ballast and the bridge deck cross beam 14 better.

[0061] Through the joint plate 17, the first stiffening rib 12 and the second stiffening rib 13, not only the bridge deck crossbeam 14, the steel bridge deck 10 and the bottom plate 11 can be strengthened respectively, but also the bonding performance between the ballast body and the steel box can be strengthened, so that the overall ballast capacity of the bridge deck system in the entire ballast area is stronger, the rigidity is greater, and the train driving performance is excellent.

[0062] Optionally, a plurality of shear nails 16 are provided on the four sides of the closed box structure to strengthen the bonding performance between the ballast body and the steel box, so that the overall ballast capacity of the bridge deck system in the entire ballast area is stronger, the rigidity is greater, and the train driving performance is excellent.

[0063] In this embodiment, Figures 1 - 2 As shown, the transverse bridge of the transverse connection 6 is bolted to the corresponding web members 3 on both sides, and the upper side of the transverse connection 6 is welded to the lower side of the upper bridge deck system. The impact of the falling bolts of the upper bridge deck system on the safety of the lower railway 7 is avoided, and the convenience of installation is guaranteed. As a preferred choice, the transverse connection 6 includes a transverse bar and a plurality of diagonal bars, the upper end of the diagonal bar is connected to the upper side of the transverse bar, and the lower end is connected to the lower side of the upper bridge deck system. The transverse bar, the upper bridge deck system and all the diagonal bars together form a plurality of equilateral triangle structures continuously arranged along the transverse bridge direction, which can reduce the rods while being combined with the upper bridge deck system to improve the support effect on the upper bridge deck system. In addition, the contact network of the lower railway 7 can be set on the upper bridge deck system crossbeam 14 or the transverse connection 6 to avoid the additional setting of the contact network fixing frame.

[0064] In this embodiment, the chords on both sides of each layer in the side span weight-bearing area, the top steel bridge deck 10, the two longitudinally adjacent bridge deck beams 14, and the bottom plate 11 all form an integrated closed box structure, and then the shrinkage compensating concrete is poured in layers by opening pouring holes in the steel bridge deck 10. The top is grouting-filled shrinkage compensating concrete to ensure dense pouring, so that the entire cross-section is a solid steel-concrete integral structure, which can not only achieve weight bearing, but also support and strengthen the upper steel bridge deck 10, so that the safety and comfort of train operation can be improved.

[0065] Example 2

[0066] This embodiment provides a main beam structure of a double-deck four-track railway steel truss cable-stayed bridge. The difference from Embodiment 1 is that the cross-sectional structure of the weight-bearing area is different. Figures 4 - 7 In this embodiment, a side plate 9 is provided between the two chord bars. Figure 4As shown in the figure, taking the setting between two lower chords 2 as an example, the steel box is composed of a bottom plate 11, side plates 9 on both lateral sides of the bridge, and two adjacent cross beams 14 of the bridge deck system. The bottom plate 11 and the side plates 9 are both arranged between two adjacent cross beams 14 of the bridge deck system. The bottom plate 11, the two side plates 9, the two cross beams 14 of the bridge deck system, and the steel bridge deck 10 enclose a closed box structure, and the ballast is filled in the closed box structure.

[0067] In this solution, the space between the bottom plate 11, the two side plates 9, and the corresponding two adjacent cross beams 14 of the bridge deck system can be filled with ballast materials, so that the ballast area structure is combined with the steel truss beam to achieve the ballast function. The ballast can be formed by pouring ballast materials such as concrete and mortar in the prior art, etc.; the specific gravity of the ballast and the closed box structure are designed according to the actual construction situation, and the bottom plate 11 and the side plates 9 are designed according to the actual construction situation.

[0068] In this solution, the bottom plate 11 and the two side plates 9 are both supported by the cross beams 14 of the bridge deck system, so there is no need to separately set up small longitudinal beams for support; and the closed box structure is a large and closed ballast box, which is formed by means of the bridge deck system of the steel truss beam and the steel bridge deck 10, simplifying the connection structure between the ballast area and the steel truss beam; and the bridge deck system of the steel truss beam and the steel bridge deck 10 are not only the bridge structure, but also part of the ballast box of the ballast, with high steel utilization rate; and the overall volume of the closed box structure is larger than that of the ballast box between two adjacent cross beams 14 of the prior art, which can reduce the specific gravity of the ballast materials, thereby reducing costs, and there is no need to increase the ballast like the prior art by increasing the height of the cross beams 14 of the bridge deck system or significantly increasing the height of the cross beams 14 of the bridge deck system; the above reasons make the steel consumption in the ballast area smaller. And because there is no need to set up small longitudinal beams, only the bottom plate 11 and the side plates 9 need to be installed between two adjacent cross beams 14 of the bridge deck system, the construction space is larger, the construction steps are fewer, and the construction is simpler; the bottom plate 11 and the side plates 9 can be installed in time after installing two adjacent cross beams 14 of the bridge deck system, which can improve the installation efficiency. After filling the closed box structure with ballast materials, the ballast materials can directly support the steel bridge deck 10, effectively improving the fatigue characteristics of the steel bridge deck 10, so that there is no need for post-maintenance of the steel bridge deck 10 and the bridge deck system below at the closed box structure, and the entire ballast area does not need maintenance.

[0069] Further preferably, the lower part of the ballast body is a normal concrete layer 151, and the upper part is a self-compacting cement mortar layer 152. By adopting a closed box structure, compared with the total volume of all ballast boxes between two adjacent bridge deck cross beams 14 in the prior art, the total volume is larger. Under the condition of ensuring the same ballast weight, normal concrete and self-compacting cement mortar with a smaller unit weight than heavy concrete can be used to achieve ballast. The normal concrete layer 151 at the lower part inside the closed box structure has strong bearing capacity, and the self-compacting cement mortar layer 152 is conducive to filling the upper part of the closed box structure, while ensuring safety and compactness. Moreover, compared with heavy concrete, filling the internal space of the closed box structure with the normal concrete layer 151 and the self-compacting cement mortar layer 152 is simpler in construction and lower in material cost itself, thereby saving construction cost.

[0070] In this embodiment, the bottom plate 11, the side plates 9, and the steel bridge deck 10 are all provided with stiffening structures. The stiffening structures are used to strengthen the bottom plate 11, the side plates 9, and the steel bridge deck 10, so that the bottom plate 11 and the side plates 9 can bear the overall pressure of the normal concrete layer 151 and the self-compacting cement mortar layer 152, and the steel bridge deck 10 can better bear the pressure of the railway 7 and the train. As Figure 4 、 5 As shown in FIGS. 7 and 7, a vertical joint plate 17 is provided along the longitudinal bridge direction at the corner of the web and the lower flange of the bridge deck cross beam 14. The stiffening structure of the bottom plate 11 is a number of second stiffening ribs 13 provided corresponding to the joint plate 17. The second stiffening ribs 13 are arranged along the longitudinal bridge direction, and the second stiffening ribs 13 and the corresponding joint plate 17 are connected by first high-strength bolts 81. The second stiffening ribs 13 are arranged along the longitudinal bridge direction and corresponding to the position of the joint plate 17 on the top surface of the bottom plate 11, which can not only ensure sufficient strengthening of the bottom plate 11, but also facilitate the more stable connection between the bottom plate 11 and the bridge deck cross beam 14. And the second stiffening ribs 13 are arranged on the top surface of the bottom plate 11, making the connection between the bottom plate 11 and the normal concrete layer 151 closer, and improving the integrity and stability of the ballast area structure.

[0071] The inner side of the side plate 9 refers to the side of the side plate 9 facing the inside of the closed box structure. As Figure 6As shown, the web of the cross beam 14 of the bridge deck system is provided with vertically arranged web stiffeners. The two longitudinal bridge sides of the side plate 9 are respectively connected to the web stiffeners of the two cross beams 14 of the bridge deck system through second high-strength bolts 82, making the connection between the side plate 9 and the cross beam 14 of the bridge deck system more stable. And the stiffening structure of the side plate 9 is a number of third stiffening ribs 131. The third stiffening ribs 131 are vertically arranged inside the side plate 9. Since the vertical height of the side plate 9 is higher than that of the existing ballast box, by arranging the vertical third stiffening ribs 131, the side plate 9 can be better strengthened. And by arranging the third stiffening ribs 131 inside the side plate 9, the side plate 9 can be more closely connected to the ordinary concrete layer 151 and the self-compacting cement mortar layer 152, improving the integrity and stability of the ballast area structure.

[0072] After being strengthened by the above-mentioned second stiffening ribs 13 and third stiffening ribs 131, it is possible to use a bottom plate 11 and a side plate 9 with a relatively thin thickness. That is, a bottom plate 11 with a thickness of 10-16 mm can be used, and a side plate 9 with a thickness of greater than or equal to 10 mm can be used. Furthermore, the steel consumption can be reduced, the cost can be saved, and it is more convenient for the hoisting of the side plate 9 and the bottom plate 11.

[0073] And the side plate 9 is provided with a manhole 91. The top of the manhole 91 is higher than the top surface of the ordinary concrete layer 151. In this embodiment, only one side plate 9 of each closed box structure is provided with one manhole 91. Through the manhole 91, the ordinary concrete layer 151 is poured. Construction workers can enter the manhole 91 to pour ordinary concrete, which is convenient for the pouring of the ordinary concrete layer 151, and can improve the pouring quality. Moreover, there is no need to separately open redundant pouring ports on the side plate 9 for pouring the ordinary concrete layer 151, which can improve the integrity of the closed box structure. And the pouring of the ordinary concrete layer 151 can be carried out in at least two layers at a time. For example, first pour the first layer 1511 at the bottom, see Figure 6 , and then pour the second layer 1512 on the top of the first layer 1511. In this pouring method, the first layer 1511 poured and the bottom plate 11 can be combined as the lower formwork together to bear the pouring of the subsequent second layer 1512. This method can make the thickness of the bottom plate 11 as thin as possible, reduce the steel consumption, and at the same time make the pouring density higher, the ballast effect and the supporting ability for the steel bridge deck 10 better. And when pouring to the height of the manhole 91, the manhole 91 needs to be blocked, and a cyclic operation mode of blocking while pouring can be adopted.

[0074] For example, the ordinary concrete layer 151 is constructed in two layers. First, the first layer 1511 is poured on the bottom plate 11. After the strength of the first layer 1511 reaches the standard, the second layer 1512 is poured on the first layer 1511. During the pouring process of the second layer 1512, when the height of the poured ordinary concrete is higher than the bottom elevation of the manhole 91, a part of the bottom of the manhole 91 is blocked first, and then the ordinary concrete is poured. When the ordinary concrete is about to overflow from the manhole 91, a part of the manhole 91 is blocked upward again, and then the ordinary concrete is poured. The ordinary concrete is poured by gradually blocking the manhole 91 upward until the second layer 1512 is poured, and then the manhole 91 is completely blocked; the bearing capacity of the ordinary concrete of the first layer 1511 is effectively utilized, so that the relatively thin bottom plate 11 and the second stiffening rib 13 only need to be able to bear the weight of the ordinary concrete of the first layer 1511. The steel-concrete structure formed by the first layer 1511 of ordinary concrete and the bottom plate 11 after molding can effectively bear the total weight of the second layer 1512 of ordinary concrete and the self-compacting cement mortar layer 152. Dividing the ordinary concrete layer 151 into two layers for construction makes the required thickness of the bottom plate 11 thinner and the required strength of the second stiffening rib 13 smaller, which can save steel and make the installation of the bottom plate 11 and the second stiffening rib 13 easier.

[0075] After the strength of the second layer 1512 reaches the standard, pouring holes are opened above the steel bridge deck 10 corresponding to between its U ribs or between the U ribs and the bridge deck longitudinal beam 18, and the self-compacting cement mortar layer 152 is poured through the pouring holes until the closed box structure is filled. Among them, the size of the pouring hole is 4 - 6 cm, preferably 5 cm, and an exhaust pipe and a pouring pipe are set. Micro-expansion self-compacting cement mortar is used for pressure grouting to ensure full filling in the ballast box. Pouring the self-compacting cement mortar layer 152 through the pouring holes can fill the closed box structure more conveniently, quickly and with high quality, and avoid incomplete filling in the corner parts of the U ribs and the bridge deck longitudinal beam 18. This construction method with the cooperation of the manhole 91 and small pouring holes can minimize the opening of a large number of relatively large pouring openings in the ballast area structure, ensure the integrity of the ballast area structure, and improve the quality of the ballast area structure.

[0076] The cross-sectional form of the ballast area of the steel truss girder cable-stayed bridge described in this embodiment has a simple structure and is convenient for installation. This ballast area structure makes better use of the main structure of the steel truss girder. Only the bottom plate 11 and the side plate 9 need to be added to connect the crossbeam 14 of the bridge deck system and cooperate with the steel bridge deck 10 to form an integral enclosed box structure as the ballast area, simplifying the connection structure between the ballast area and the steel truss girder. And it is connected by the first high-strength bolt 81 and the second high-strength bolt 82, which can be installed in blocks and is convenient for construction. Moreover, its structure has clear force transmission, does not change the force system and mechanical properties of the steel truss girder, and the cable force still maintains the force transmission path from the chord to the bridge deck. It has good economy. Compared with the traditional ballast box, it can save more than 40% of steel. Two kinds of ballast materials are used. The bottom ordinary concrete layer 151 has strong bearing capacity, and the top self-compacting cement mortar layer 152 is convenient for pouring through small holes opened on the top plate, ensuring the compactness. And the structure of this ballast area is highly safe. After the ordinary concrete of the ordinary concrete layer 151 is formed, it forms an integral body with the bottom plate 11, and there is a connection between the first high-strength bolt 81 and the crossbeam 14 of the bridge deck system. Even if the first high-strength bolt 81 fails, the structure of this ballast area can still effectively support on the lower flange of the crossbeam 14 of the bridge deck system and will not fall off. And it also has the characteristics of being maintenance-free and having strong durability. The enclosed box structure is filled with ordinary concrete and self-compacting cement mortar, and no maintenance is required; the steel bridge deck 10 is supported by the enclosed box structure, the ordinary concrete layer 151 and the self-compacting cement mortar layer 152 inside it, the stress is improved, and the durability is enhanced. And the outer surface of the enclosed box structure is smooth and clean, which is convenient for maintenance.

[0077] The main girder structure of the double-deck four-track railway steel truss girder cable-stayed bridge in the above-mentioned Embodiment 1 and Embodiment 2, compared with the traditional steel truss girder section where the four-track railway is placed on the same layer, the double-deck four-track railway orthotropic steel plate main girder section can reduce the truss width, make the best use of the cross-sectional size, and reduce the steel consumption. And it can realize the form of passenger and freight separation, achieve the separation of passenger and freight traffic, and reduce their mutual influence. The orthotropic steel plate is adopted in the non-ballast sections of the mid-span and side spans, and the steel box concrete composite bridge deck structure is adopted in the ballast section of the side span, solving the problem of ballasting of multi-track steel truss girders. The ballast structure is combined with the stress structure, with good economy and no need for maintenance. The steel box can use a 10 - 12 mm thick panel and 8 mm stiffeners. Compared with the traditional structure of a 16 mm bridge deck + U ribs + steel ballast box, it can save more than 40% of steel. The steel box concrete composite bridge deck structure does not need to arrange prestress, and relies on the top steel bridge deck 10 to resist the negative moment effect of the auxiliary pier, avoiding the problem of durability affected by the cracking of the concrete bridge deck. The top surface is fully welded and the side is bolted with a cross connection 6 structure, avoiding the impact of the falling of bolts on the upper bridge deck on the safety of the lower railway 7, and ensuring the installation convenience. Compared with the flat-layer structure and the all-steel bridge deck truss girder structure, it has a large stiffness and excellent train running performance.

[0078] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. The main beam structure of a double - layer four - line railway steel truss girder cable - stayed bridge is characterized in that, It includes main girders located on both lateral sides of the bridge. The main girders include upper chord bars (1), lower chord bars (2), and several vertically arranged web members (3). The upper chord bars (1) and the lower chord bars (2) are both arranged along the longitudinal direction of the bridge. The upper ends of the web members (3) are connected to the upper chord bars (1), and the lower ends are connected to the lower chord bars (2). All the web members (3) are arranged at intervals along the longitudinal direction of the bridge. A lower bridge deck system is connected between the two lower chord bars (2) of the two main girders. An upper bridge deck system is connected between the two upper chord bars (1) of the two main girders. Two railways (7) are respectively arranged above the lower bridge deck system and above the upper bridge deck system. The two railways (7) above the upper bridge deck system are correspondingly arranged directly above the two railways (7) above the lower bridge deck system. The longitudinal directions of the upper bridge deck system and the lower bridge deck system are both provided with bridge deck cross beams (14) at intervals. The two ends of the bridge deck cross beams (14) are correspondingly connected to the upper chord bars (1) or the lower chord bars (2) of the main girders on both sides. Transverse bracings (6) are connected between the tops of the corresponding two web members (3) of the main girders on both sides. The upper side of the transverse bracing (6) is connected to the lower side of the upper bridge deck system. The upper bridge deck system is longitudinally divided into a first bridge deck system (41) and a second bridge deck system (42). The first bridge deck system (41) corresponds to the non-ballast sections of the mid-span and side spans of the bridge. The second bridge deck system (42) corresponds to the ballast sections of the side spans of the bridge. The lower bridge deck system is longitudinally divided into a third bridge deck system (51) and a fourth bridge deck system (52). The third bridge deck system (51) corresponds to the non-ballast sections of the mid-span and side spans of the bridge. The fourth bridge deck system (52) corresponds to the ballast sections of the side spans of the bridge. The first bridge deck system (41) and the third bridge deck system (51) are both orthotropic plates. The top surface of the orthotropic plate is used to set the railway (7). The second bridge deck system (42) and / or the fourth bridge deck system (52) includes a steel box, a steel bridge deck (10) on the top of the steel box, and a ballast body filled in the steel box. The steel bridge deck (10) is used to set the railway (7). The steel box is composed of a bottom plate (11), side plates (9) on both lateral sides of the bridge, and two adjacent bridge deck cross beams (14). The bottom plate (11) and the side plates (9) are both arranged between two adjacent bridge deck cross beams (14). The bottom plate (11), the two side plates (9), the two bridge deck cross beams (14), and the steel bridge deck (10) enclose a closed box structure. The ballast body is filled in the closed box structure. The lower part of the ballast body is a normal concrete layer (151), and the upper part is a self-compacting cement mortar layer (152).

2. The main girder structure of the double-deck four-line railway steel truss cable-stayed bridge according to claim 1, wherein Several first stiffening ribs (12) are distributed at intervals along the transverse direction at the bottom of the steel bridge deck (10). The first stiffening ribs (12) are arranged along the longitudinal direction of the bridge. When the lower part of the ballast body is a normal concrete layer (151), the top surface height of the normal concrete layer (151) is not higher than the bottom of the first stiffening ribs (12) of the steel bridge deck (10).

3. The main girder structure of the double-deck four-track railway steel truss cable-stayed bridge according to claim 1, wherein, Above the bottom plate (11), there are several second stiffening ribs (13) arranged along the longitudinal bridge direction. At the corner of the web and the lower flange of the cross beam (14) of the deck system, a joint plate (17) is vertically arranged along the longitudinal bridge direction. The second stiffening rib (13) is connected to the corresponding joint plate (17) of the cross beam (14) of the deck system by a first high-strength bolt (81). And / or; Several shear studs (16) are provided on all four sides of the closed box structure.

4. The main beam structure of a double-deck four-line railway steel truss girder cable-stayed bridge is characterized in that It includes main trusses on both lateral sides of the bridge. The main trusses include upper chord members (1), lower chord members (2), and several vertically arranged web members (3). The upper chord members (1) and the lower chord members (2) are both arranged along the longitudinal bridge direction. The upper ends of the web members (3) are connected to the upper chord members (1), and the lower ends are connected to the lower chord members (2). All the web members (3) are arranged at intervals along the longitudinal bridge direction. A lower deck system is connected between the two lower chord members (2) of the two main trusses, and an upper deck system is connected between the two upper chord members (1) of the two main trusses. Two railways (7) are respectively arranged above the lower deck system and above the upper deck system. The two railways (7) above the upper deck system are correspondingly arranged directly above the two railways (7) above the lower deck system. The longitudinal bridge directions of the upper deck system and the lower deck system are both provided with cross beams (14) of the deck system at intervals. The two ends of the cross beam (14) of the deck system are correspondingly connected to the upper chord members (1) or the lower chord members (2) of the two main trusses on both sides. Cross bracings (6) are connected between the tops of the corresponding two web members (3) of the two main trusses on both sides. The upper side of the cross bracing (6) is connected to the lower side of the upper deck system. The upper deck system is longitudinally divided into a first deck system (41) and a second deck system (42). The first deck system (41) corresponds to the non-ballast sections of the mid-span and the side spans of the bridge. The second deck system (42) corresponds to the ballast section of the side span of the bridge. The lower deck system is longitudinally divided into a third deck system (51) and a fourth deck system (52). The third deck system (51) corresponds to the non-ballast sections of the mid-span and the side spans of the bridge. The fourth deck system (52) corresponds to the ballast section of the side span of the bridge. Both the first deck system (41) and the third deck system (51) are orthotropic plates, and the top surfaces of the orthotropic plates are used to arrange the railways (7). The second deck system (42) and / or the fourth deck system (52) includes a steel box, a steel bridge deck (10) on the top of the steel box, and a ballast body filled in the steel box. The steel bridge deck (10) is used to arrange the railways (7). The steel box of the second deck system (42) is composed of a bottom plate (11), the upper chord members (1) on both lateral sides of the bridge, and two adjacent cross beams (14) of the deck system. The bottom plate (11) is arranged between two adjacent cross beams (14) of the deck system. The bottom plate (11), the upper chord members (1) on both sides, the two cross beams (14) of the deck system, and the steel bridge deck (10) enclose a closed box structure, and the ballast body is filled in the closed box structure. The steel box of the fourth bridge deck system (52) is composed of a bottom plate (11), lower chord members (2) on both lateral sides of the bridge, and two adjacent bridge deck system cross beams (14). The bottom plate (11) is arranged between two adjacent bridge deck system cross beams (14). The bottom plate (11), the lower chord members (2) on both sides, the two bridge deck system cross beams (14), and the steel bridge deck (10) enclose a closed box structure, and the ballast is filled in the closed box structure.

5. The main girder structure of the double-layer four-track railway steel truss girder cable-stayed bridge according to claim 4, wherein, The steel box is only provided in the fourth bridge deck system (52); Or, The steel box is provided in both the fourth bridge deck system (52) and the second bridge deck system (42), and the volume of the steel box of the fourth bridge deck system (52) is larger than the volume of the steel box of the second bridge deck system (42).

6. The main girder structure of the double-deck four-track railway steel truss cable-stayed bridge according to claim 4, characterized in that The ballast includes at least two layers of shrinkage compensation concrete layers (153) filled in a layered manner.

7. The main girder structure of the double-layer four-track railway steel truss cable-stayed bridge according to any one of claims 4-6, characterized in that A number of first stiffening ribs (12) are distributed at intervals along the transverse direction of the bridge at the bottom of the steel bridge deck (10), and the first stiffening ribs (12) are arranged along the longitudinal direction of the bridge; When the lower part of the ballast is a normal concrete layer (151), the top surface height of the normal concrete layer (151) is not higher than the bottom of the first stiffening rib (12) of the steel bridge deck (10).

8. The main girder structure of the double-deck four-track railway steel truss cable-stayed bridge according to any one of claims 4-6, characterized in that A number of second stiffening ribs (13) are provided above the bottom plate (11), and the number of second stiffening ribs (13) is arranged along the longitudinal direction of the bridge. At the corner of the web and the lower flange of the bridge deck system cross beam (14), a joint plate (17) is vertically arranged along the longitudinal direction of the bridge. The second stiffening rib (13) is connected to the corresponding joint plate (17) of the bridge deck system cross beam (14) by a first high-strength bolt (81); And / or; A number of shear studs (16) are provided on all four sides of the closed box structure.

9. The main girder structure of the double-layer four-track railway steel truss cable-stayed bridge according to any one of claims 4-6, characterized in that, Both lateral sides in the transverse direction of the cross bracing (6) are bolted to the corresponding web members (3), and the upper side of the cross bracing (6) is welded to the lower side of the upper bridge deck system.

10. The main girder structure of the double-deck four-line railway steel truss cable-stayed bridge according to claim 9, characterized in that, The cross bracing (6) includes a cross bar and a number of diagonal bars. The upper ends of the diagonal bars are connected to the upper side of the cross bar, and the lower ends are connected to the lower side of the upper bridge deck system. The cross bar, the upper bridge deck system, and all the diagonal bars together form a number of equilateral triangle structures arranged continuously along the transverse direction of the bridge.

Images