Multi-main-truss steel truss girder bridge

Abstract

According to the multi-main-truss steel truss girder bridge, two main trusses are transversely arranged in a spaced mode to bear main line loads, an auxiliary truss is introduced into the key Nth span section (interchange area), the starting end of the auxiliary truss extends to the (N-1) th span section and is in rigid connection with the main trusses, and the auxiliary truss and the main trusses form an overall frame in the intersection area; loads are longitudinally transmitted to the auxiliary trusses through the main trusses and then dispersed to the bridge piers, concentrated stress of a traditional independent large-span structure is avoided, the overall rigidity of the structure is remarkably improved through the synergistic effect of the main trusses and the auxiliary trusses, the mid-span deflection is reduced, the redundant span matching requirement is lowered, independent design of a traditional large-span steel box girder is directly replaced, redundant structure materials are reduced, and cost is reduced. Meanwhile, the increase of the number of piers caused by span redundancy is avoided, an integral bridge floor is formed in front of a bridge floor separation point, the bridge floor separation point is naturally divided into a main line bridge floor and a ramp bridge floor, the integral bridge floor part in front of the separation point is jointly supported by a main truss and an auxiliary truss, the auxiliary truss mainly bears the ramp load after separation, and the main truss mainly bears the main line load.

Description

Technical Field

[0001] The present application relates to the field of steel truss bridges, and in particular to a multi-main-truss steel truss bridge. Background Art

[0002] At the intersection of the main line and the on- and off-ramps of urban interchanges, there is often a significant gradient in bridge deck width. For small to medium spans, this area often employs variable-section box girders (variable-width design) to achieve a smooth transition. Once the ramps separate from the main line, they are connected by independent structures (such as simply supported beams or continuous beam bridges).

[0003] In related technologies, as urban spatial constraints tighten and construction conditions become increasingly demanding, interchanges often need to directly connect to ramps within the confines of the main steel truss bridge, forcing the ramp bridge and the main line to adopt long-span structures simultaneously. However, if independent long-span steel box girders are forced to be used, redundant spans will be required to meet the load, resulting in a surge in material consumption, further increasing project costs and construction risks. Summary of the Invention

[0004] The present application provides a multi-main-truss steel truss bridge, which can solve the technical problem that the traditional solution of using independent large-span steel box girders at the intersection of the main line and the entrance and exit ramps of urban interchanges leads to a surge in material consumption, further increasing the project cost and construction risks.

[0005] An embodiment of the present application provides a multi-main-truss steel truss bridge, comprising: At least two main trusses, the two main trusses are spaced apart in the transverse direction of the bridge and extend in the longitudinal direction of the bridge, and are used to carry mainline traffic. The main trusses are divided into an N-2 span, an N-1 span, and an N span in sequence along their length, and the N span is arranged in the interchange area; A secondary truss is arranged in the Nth span, and its starting end extends to the N-1th span and is connected to one side of the main truss. The main truss and the secondary truss are provided with a bridge deck separation point in the Nth span, and form an integral bridge deck before the bridge deck separation point, and form independent main line bridge decks and ramp bridge decks after the bridge deck separation point.

[0006] In one embodiment, the number of the secondary trusses is two, and the two secondary trusses are arranged on the sides of the two main trusses that are away from each other.

[0007] In one embodiment, the centerline extension direction of the secondary truss is consistent with the direction of the ramp line, and the secondary truss is used to support pier n and pier n-1.

[0008] In one embodiment, within the N-1 span and along the direction from the N-2 span to the N-1 span, at least part of the overall bridge deck of the two main trusses gradually widens and widens to the N-1 span.

[0009] In one embodiment, the secondary truss upper chord of the secondary truss is fixedly connected to the main truss upper chord of the main truss, and the secondary truss lower chord of the secondary truss is fixedly connected to the main truss lower chord of the main truss, so as to fix the starting end of the secondary truss to one side of the main truss, and a secondary truss web is arranged between the secondary truss upper chord and the secondary truss lower chord of the secondary truss.

[0010] In one embodiment, before the bridge deck separation point, the main truss and the secondary truss are fixed with a connecting beam at a node position, and the top surfaces of the main truss and the secondary truss are at the same height.

[0011] In one embodiment, after the bridge deck separation point, the top surface height of the secondary truss upper chord of the secondary truss gradually becomes higher or lower, and the rising slope or the falling slope is used to be consistent with the longitudinal slope of the ramp, and the secondary truss upper chord of the secondary truss and the main truss upper chord of the main truss are fixed with a height-varying crossbeam at the node position, and the heights of the two ends of the height-varying crossbeam are inconsistent to adapt to the height difference between the ramp bridge deck of the secondary truss and the main line bridge deck of the main truss.

[0012] In one embodiment, a transverse connection system is fixed between the secondary truss and the main truss after the bridge deck separation point.

[0013] In one embodiment, the transverse linkage comprises cross-shaped diagonal rods or V-shaped rods.

[0014] In one embodiment, the integral bridge deck structure, the mainline bridge deck, and the ramp bridge deck include steel bridge decks or concrete bridge decks.

[0015] The beneficial effects of the technical solutions provided in the embodiments of the present application include: Two main trusses are arranged at intervals laterally to bear the mainline load, and a secondary truss is introduced in the critical Nth span (interchange area). Its starting end extends to the N-1th span and is rigidly connected to the main truss. The secondary truss and the main truss form an integral frame at the intersection. The synergistic effect of the main truss and the secondary truss significantly improves the overall stiffness of the structure, reduces the mid-span deflection, avoids redundant spans, and directly replaces the independent design of traditional large-span steel box girders, reducing redundant structural materials. An integral bridge deck is formed before the bridge deck separation point, and is naturally divided into the mainline bridge deck and the ramp bridge deck after the separation point. The integral bridge deck before the separation point is jointly supported by the main and secondary trusses. After the separation, the secondary truss mainly bears the ramp load, and the main truss mainly bears the mainline load. The load distribution path is optimized and the main truss and secondary trusses are used to bear the load in coordination, thereby improving the utilization efficiency of materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 This is a structural diagram of the main truss from the perspective of the transverse direction of the bridge; Figure 2 This is a structural diagram of the secondary truss from the perspective of the bridge transverse direction; Figure 3 Schematic diagram of the upper structure from a top-down perspective of the main truss and secondary truss; Figure 4 Schematic diagram of the lower structure of the main truss and secondary truss from an upward perspective; Figure 5 for Figure 3 Cross-sectional view of AA; Figure 6 for Figure 3 Cross-sectional view of the middle BB; Figure 7 for Figure 3 Cross-sectional view of CC; Figure 8 for Figure 3 Cross-sectional view of DD.

[0018] In the figure: 1. Main truss; 11. Main truss upper chord; 12. Main truss lower chord; 13. Main truss web; 2. Auxiliary truss; 21. Auxiliary truss upper chord; 22. Auxiliary truss lower chord; 23. Auxiliary truss web; 3. Deck separation point; 4. Overall deck; 5. Mainline deck; 6. Ramp deck; 7. Connecting beam; 8. Variable height beam; 9. Transverse connection system. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] It's important to understand that urban overpasses are key nodes in the transportation network, and their design and function directly impact urban traffic efficiency. Fully known as "three-dimensional intersection bridges," overpasses utilize a layered design to enable unimpeded passage through intersecting roads, eliminating traffic stoppages and congestion caused by traffic lights. Dedicated lanes can also be designed for pedestrians and non-motorized vehicles. At the intersection of the main line and the entrance and exit ramps of an urban overpass, the bridge deck width typically exhibits a significant gradient. For small and medium spans, this area often utilizes variable-section box girders (variable-width design) to achieve a smooth transition. Once the ramps separate from the main line, they are connected via independent structures (such as simply supported beams or continuous beam bridges).

[0021] With tightening urban space constraints and complex construction conditions, overpasses often need to connect directly to ramps within the confines of the main steel truss bridge, forcing the ramp bridge and the main line to adopt long-span structures. However, if independent long-span steel box girders are forced to be used, redundant spans will be required to meet the load, resulting in a surge in material consumption, further increasing project costs and construction risks.

[0022] The embodiment of the present application provides a multi-main-truss steel truss bridge, which can solve the technical problem that the traditional solution of using independent large-span steel box girders at the intersection of the main line and the entrance and exit ramps of urban interchanges leads to a surge in material consumption, further increasing the project cost and construction risks.

[0023] like Figure 1 、 Figure 2 、 Figure 3 and Figure 4 As shown, an embodiment of the present application provides a multi-main-truss steel truss bridge, which includes: at least two main trusses 1, the two main trusses 1 are arranged at intervals along the transverse direction of the bridge, and both extend along the longitudinal direction of the bridge, which are used to carry main line traffic, and the main truss 1 is divided into the N-2 span, the N-1 span and the N span in sequence along its own length direction, and the N span is arranged in the overpass area; the secondary truss 2 is arranged in the N span, and its starting end extends to the N-1 span, and is connected to one side of the main truss 1, and the main truss 1 and the secondary truss 2 are provided with a bridge deck separation point 3 in the N span, and form an integral bridge deck 4 before the bridge deck separation point 3, and form an independent main line bridge deck 5 and ramp bridge deck 6 after the bridge deck separation point 3.

[0024] In this embodiment, two main trusses 1 are arranged laterally at intervals to bear the mainline load, and a secondary truss 2 is introduced in the critical Nth span (interchange area). Its starting end extends to the N-1th span and is rigidly connected to the main truss 1. The main truss 1 and the secondary truss 2 work together to significantly improve the overall stiffness of the structure, reduce mid-span deflection, and reduce the need for redundant spans. This directly replaces the independent design of traditional large-span steel box girders, reduces redundant structural materials, and avoids the increase in the number of piers due to span redundancy. An integral bridge deck 4 is formed before the bridge deck separation point 3, and is naturally divided into a mainline bridge deck 5 and a ramp bridge deck 6 after the separation point. The integral bridge deck 4 before the separation point is supported by both the main and secondary trusses. After the separation, the secondary truss 2 bears the ramp load, and the main truss 1 mainly bears the mainline load. This optimizes the load distribution path, utilizes the main truss 1 and the secondary truss 2 to bear the load in coordination, and improves material utilization efficiency.

[0025] In one embodiment, Figure 3 As shown, there are two secondary trusses 2 , and the two secondary trusses 2 are arranged on the sides of the two main trusses 1 that are away from each other.

[0026] In this embodiment, two secondary trusses 2 are located outside the corresponding main trusses 1 and are rigidly connected to form a dual-channel ramp bridge deck 6, thereby increasing the number of ramps.

[0027] In one embodiment, Figure 3 As shown, the extension direction of the centerline of the secondary truss 2 is consistent with the direction of the ramp line, and the secondary truss 2 is used to support pier n and pier n-1.

[0028] In this embodiment, the centerline of the secondary truss 2 extends in the same direction as the ramp route, forming a "ramp-secondary truss 2 axis collinear" layout. The secondary truss 2 extends directly along the ramp trajectory, so that the load transfer path of the ramp bridge deck 6 coincides with the axis of the secondary truss 2, avoiding excessive eccentric bending moment (avoiding torsional effects). The two ends of the secondary truss 2 are supported by pier n (mainline pier) and pier n-1 (transition pier), sharing the same pier system with the main truss 1. Piers n and n-1 carry both the mainline load of the main truss 1 and the ramp load of the secondary truss 2. The dual-function pier design reduces the number of independent pier columns.

[0029] In one embodiment, Figure 3 As shown, within the N-1 span and along the direction from the N-2 span to the N-1 span, at least part of the overall bridge deck 4 of the two main trusses 1 gradually widens and widens to the N-1 span.

[0030] In one embodiment, Figure 2 、 Figure 3 and Figure 4As shown, the secondary truss upper chord 21 of the secondary truss 2 is fixedly connected to the main truss upper chord 11 of the main truss 1, and the secondary truss lower chord 22 of the secondary truss 2 is fixedly connected to the main truss lower chord 12 of the main truss 1, so as to fix the starting end of the secondary truss 2 to one side of the main truss 1, and the secondary truss web 23 is arranged between the secondary truss upper chord 21 and the secondary truss lower chord 22 of the secondary truss 2.

[0031] In this embodiment, the main truss 1 and secondary trusses 2 are rigidly connected via chords to form an integrated load-bearing system, significantly improving the bridge's lateral stiffness and torsional resistance. The secondary truss upper chord 21 is fixedly connected to the main truss upper chord 11, and the secondary truss lower chord 22 is fixedly connected to the main truss lower chord 12. This enables bidirectional transmission of axial forces and bending moments between the main trusses 1 and 2, while the secondary truss webs 23 form a stable truss unit.

[0032] In one embodiment, Figure 1 As shown, a main truss web 13 is arranged between the main truss upper chord 11 and the main truss lower chord 12 of the main truss 1 .

[0033] In one embodiment, Figure 7 As shown, before the bridge deck separation point 3, the main truss 1 and the secondary truss 2 are fixed with a connecting beam 7 at the node position, and the top surfaces of the main truss 1 and the secondary truss 2 are at the same height.

[0034] In this embodiment, the connecting beam 7 securely connects the nodes of the main truss 1 and the secondary truss 2 to form a bidirectional load transfer path to jointly resist bridge deck loads (such as vehicle eccentric loads and wind loads).

[0035] In one embodiment, Figure 8 As shown, after the bridge deck separation point 3, the top surface height of the secondary truss upper chord 21 of the secondary truss 2 gradually becomes higher or lower, and the rising slope or the falling slope is used to be consistent with the longitudinal slope of the ramp, and the secondary truss upper chord 21 of the secondary truss 2 and the main truss upper chord 11 of the main truss 1 are fixed with a height-changing crossbeam 8 at the node position, and the heights of the two ends of the height-changing crossbeam 8 are inconsistent to adapt to the height difference between the ramp bridge deck 6 of the secondary truss 2 and the main line bridge deck 5 of the main truss 1.

[0036] In this embodiment, the top surface of the secondary truss upper chord 21 of the secondary truss 2 gradually changes longitudinally (raises or lowers) after the bridge deck separation point 3. Its slope is consistent with the longitudinal slope of the ramp, ensuring a smooth connection between the longitudinal slopes of the ramp deck 6 and the mainline deck 5. By adjusting the height of the secondary truss upper chord 21, the longitudinal slope of the ramp deck 6 is matched with the line design. The height difference between the upper chords of the main truss 1 and the secondary truss 2 is transitioned by a variable height beam 8. The variable height beam 8 is fixed at the node of the main truss upper chord 11 and the secondary truss upper chord 21. Its two ends support the mainline deck 5 (higher) and the ramp deck 6 (lower), respectively. The variable height beam 8 adopts a variable cross-section design, and ultimately the main truss 1 and the secondary truss 2 coordinately distribute the force.

[0037] In one embodiment, Figure 8 As shown, after the bridge deck separation point 3, a transverse connection system 9 is fixed between the secondary truss 2 and the main truss 1.

[0038] In this embodiment, the transverse connecting system 9 is arranged after the bridge deck separation point 3, connecting the main truss 1 and the secondary truss 2. The rigid connection eliminates the difference in lateral displacement between the main truss 1 and the secondary truss 2, prevents the ramp bridge deck 6 and the mainline bridge deck 5 from slipping and deformation due to uneven loads, and transfers the ramp live load (such as vehicle centrifugal force and lateral wind load) on the secondary truss 2 to the main truss 1.

[0039] In one embodiment, the transverse coupling system 9 comprises cross-shaped diagonal rods or V-shaped rods.

[0040] In this embodiment, the transverse connecting system 9 connects the main truss 1 and the secondary truss 2 through cross diagonal rods or V-shaped rods to form a stable spatial structure, which mainly bears the transverse load (such as wind load and vehicle centrifugal force) and improves the torsional stiffness of the bridge span structure. The cross diagonal rods are arranged along the diagonal line of the transverse bridge to form an "X"-shaped cross structure, and the V-shaped rods are arranged in an asymmetric or symmetrical "V" shape.

[0041] In one embodiment, the overall bridge deck 4 structure, the mainline bridge deck 5 and the ramp bridge deck 6 include steel bridge decks or concrete bridge decks.

[0042] In this embodiment, the steel bridge deck is lightweight, quick to construct, and suitable for large-span complex structures; the concrete bridge deck has the advantages of high economy, easy maintenance, and adaptability to heavy-load traffic.

[0043] On the other hand, Figure 1 、 Figure 2 、 Figure 3 and Figure 4 As shown, the present application provides an urban overpass, which includes a multi-main truss steel truss bridge, and the multi-main truss steel truss bridge includes: at least two main trusses 1, the two main trusses 1 are arranged at intervals along the transverse bridge direction, and both extend along the longitudinal bridge direction, which are used to carry main line traffic, and the main truss 1 is divided into the N-2 span, the N-1 span and the N span in sequence along its own length direction, and the N span is arranged in the overpass area; the secondary truss 2 is arranged in the N span, and its starting end extends to the N-1 span, and is connected to one side of the main truss 1, and the main truss 1 and the secondary truss 2 are provided with a bridge deck separation point 3 in the N span, and form an integral bridge deck 4 before the bridge deck separation point 3, and form an independent main line bridge deck 5 and ramp bridge deck 6 after the bridge deck separation point 3.

[0044] In this embodiment, two main trusses 1 are arranged laterally at intervals to bear the mainline load, and a secondary truss 2 is introduced in the critical Nth span (interchange area). The starting end of the secondary truss 2 extends to the N-1th span and is rigidly connected to the main truss 1. The secondary truss 2 and the main truss 1 form an integral frame at the intersection. The synergistic effect of the main truss 1 and the secondary truss 2 significantly improves the overall stiffness of the structure, reduces mid-span deflection, and reduces the need for redundant spans. This directly replaces the independent design of traditional large-span steel box girders and reduces redundant structural materials. An integral bridge deck 4 is formed before the bridge deck separation point 3, and is naturally divided into a mainline bridge deck 5 and a ramp bridge deck 6 after the separation point. The integral bridge deck 4 before the separation point is supported by both the main and secondary trusses. After the separation, the secondary truss 2 bears the ramp load, and the main truss 1 mainly bears the mainline load. This optimizes the load distribution path, utilizes the main truss 1 and the secondary truss 2 to bear the load in coordination, and improves material utilization efficiency.

[0045] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0046] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0047] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A multi-main-truss steel truss bridge, characterized in that: It includes: At least two main trusses (1), the two main trusses (1) are spaced apart in the transverse direction of the bridge and both extend in the longitudinal direction of the bridge, and are used to carry mainline traffic. The main trusses (1) are divided into an N-2 span, an N-1 span, and an N span in sequence along their own length direction, and the N span is arranged in the interchange area; A secondary truss (2), wherein the secondary truss (2) is arranged in the Nth span, and its starting end extends to the N-1th span and is connected to one side of the main truss (1), and the main truss (1) and the secondary truss (2) are provided with a bridge deck separation point (3) in the Nth span, and form an integral bridge deck (4) before the bridge deck separation point (3), and form an independent main line bridge deck (5) and a ramp bridge deck (6) after the bridge deck separation point (3).

2. The multi-main-truss steel truss bridge according to claim 1, characterized in that: There are two secondary trusses (2), and the two secondary trusses (2) are arranged on the sides of the two main trusses (1) that are away from each other.

3. The multi-main-truss steel truss bridge according to claim 1, characterized in that: The centerline extension direction of the secondary truss (2) is used to be consistent with the direction of the ramp line, and the secondary truss (2) is used to support the n pier and the n-1 pier.

4. The multi-main-truss steel truss bridge according to claim 1, characterized in that: In the N-1 span and along the direction from the N-2 span to the N-1 span, at least a portion of the overall bridge deck (4) of the two main trusses (1) gradually widens and widens to the N-1 span.

5. The multi-main-truss steel truss bridge according to claim 1, characterized in that: The secondary truss upper chord (21) of the secondary truss (2) is fixedly connected to the main truss upper chord (11) of the main truss (1), and the secondary truss lower chord (22) of the secondary truss (2) is fixedly connected to the main truss lower chord (12) of the main truss (1), so as to fix the starting end of the secondary truss (2) to one side of the main truss (1), and a secondary truss web (23) is provided between the secondary truss upper chord (21) and the secondary truss lower chord (22) of the secondary truss (2).

6. The multi-main-truss steel truss bridge according to claim 1, characterized in that: Before the bridge deck separation point (3), the main truss (1) and the secondary truss (2) are fixed with a connecting crossbeam (7) at a node position, and the top surfaces of the main truss (1) and the secondary truss (2) are at the same height.

7. The multi-main-truss steel truss bridge according to claim 1, characterized in that: After the bridge deck separation point (3), the top surface height of the secondary truss upper chord (21) of the secondary truss (2) gradually becomes higher or lower, and the rising slope or the falling slope is used to be consistent with the longitudinal slope of the ramp, and the secondary truss upper chord (21) of the secondary truss (2) and the main truss upper chord (11) of the main truss (1) are fixed with a height-changing crossbeam (8) at the node position, and the heights of the two ends of the height-changing crossbeam (8) are inconsistent to adapt to the height difference between the ramp bridge deck (6) of the secondary truss (2) and the main line bridge deck (5) of the main truss (1).

8. The multi-main-truss steel truss bridge according to claim 1, wherein: After the bridge deck separation point (3), a transverse connection system (9) is fixed between the secondary truss (2) and the main truss (1).

9. The multi-main-truss steel truss bridge according to claim 8, characterized in that: The transverse connecting system (9) comprises cross diagonal rods or V-shaped rods.

10. The multi-main-truss steel truss bridge according to claim 1, wherein: The integral bridge deck (4) structure, the main line bridge deck (5) and the ramp bridge deck (6) include steel bridge decks or concrete bridge decks.

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