Special-shaped steel truss girder structure at tower beam joint and construction method thereof

Abstract

The present application relates to a kind of tower beam connection's special-shaped steel truss beam structure and its construction method.Currently inverted trapezoidal section girder adopts tower beam consolidation, and there are problems such as unreasonable stress, poor economy in tower beam connection.The steel truss beam in the structure includes inverted trapezoidal section segment, rectangular section segment and special-shaped transition segment, the rectangular section segment is located above the pier, and the longitudinal two sides of rectangular section segment are special-shaped transition segment and inverted trapezoidal section segment from near to far in sequence;The top of rectangular section segment and the top of inverted trapezoidal section segment are transversely same width, the bottom of rectangular section segment is greater than the bottom of inverted trapezoidal section segment in transverse width, and rectangular section segment is connected to inverted trapezoidal section segment by the horizontal inclined rod of special-shaped transition segment.The present application adopts the inverted trapezoidal section of upper wide lower narrow and the special-shaped structure design of rectangular section combination, simultaneously meet the demand of different sizes of section for dual-purpose bridge of highway and railway and the transmission demand of huge axial force for steel truss beam at bridge tower, so that structure material use and stress are more reasonable.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering technology, specifically to an irregularly shaped steel truss girder structure at the tower-beam connection and its construction method. Background Technology

[0002] For large or extra-large bridges with complex foundation engineering and high pier and abutment costs, as well as those located near cities with dense railway and highway connections requiring the construction of both railway and highway bridges, dual-purpose road-rail bridges can be considered in order to reduce costs and shorten construction time. Considering factors such as load, connection relationships, and safety, dual-purpose road-rail bridges generally adopt a double-layer cross-section layout with the highway on top and the railway below. Furthermore, highway bridges typically have 6-8 lanes and a wider deck, while railway bridges generally have double tracks and require a narrower deck. Therefore, from the perspectives of cross-sectional requirements and economy, the inverted trapezoidal cross-section, wider at the top and narrower at the bottom, becomes the typical cross-sectional form for dual-purpose road-rail steel truss bridges.

[0003] However, in dual-purpose (road and rail) steel truss bridges with a wider top and narrower bottom, when the structure is a low-tower cable-stayed bridge with a fixed tower-beam configuration and separate towers and piers, the steel truss section connecting the towers, due to its trapezoidal cross-section (wider at the top and narrower at the bottom), cannot directly transfer the enormous axial force to the piers. This causes the force flow to be transmitted within the inverted trapezoidal transverse frame, making the design of the inverted trapezoidal main beam cross-section at the towers difficult. Currently, the problem of enormous transverse frame internal forces at the towers of low-tower cable-stayed bridges with a fixed tower-beam configuration and separate towers and piers is usually solved by changing the bridge's structural stress system or uniformly changing the inverted trapezoidal cross-section to a rectangular cross-section to quickly transfer the axial force from the towers. However, these measures all have technical drawbacks. Specifically:

[0004] 1. The steel truss with an inverted trapezoidal cross section is not compatible with the structure of a low-tower cable-stayed bridge where the tower and beam are fixed together and the tower and pier are separate.

[0005] Low-tower cable-stayed bridges employ a structural system of tower-beam integration and tower-pier separation, which can solve the design problem of temperature effects in long-span steel truss bridges. At the same time, the steel truss adopts an inverted trapezoidal cross-section, which can meet the width requirements of highway and railway traffic with the most economical cross-sectional layout. However, when the two structures are combined, at the tower-beam connection, the bridge tower of the low-tower cable-stayed bridge, which adopts a tower-beam integration and tower-pier separation structural system, directly acts on the outside of the inverted trapezoidal cross-section, causing the structure to generate huge axial forces and bending moments, making the design of the members very difficult and making it impossible to guarantee the safety and rationality of the structure.

[0006] 2. The steel truss uses a rectangular cross-section with the same width at the top and bottom, which is not economical.

[0007] When the inverted trapezoidal section of the steel truss, which is wider at the top and narrower at the bottom, is replaced with a rectangular section of the same width at both the top and bottom, the force transmission between the tower and the beam, and between the web members of the bridge tower and the main truss, is smooth. The huge axial force of the bridge tower can be quickly transferred to the pier. The force transmission of the structure is clear, and the member design is also more reasonable. However, since the required width of the railway bridge deck is narrower than that of the highway bridge deck, even with the use of openwork treatment outside the railway carriageway, the rectangular section of the same width at both the top and bottom still uses more steel per meter than the inverted trapezoidal section of ...

[0008] 3. The stress distribution of the low-tower cable-stayed bridge, which adopts a structural system of tower-pier consolidation and tower-beam separation with inverted trapezoidal cross-section, can be further optimized.

[0009] Inverted trapezoidal cross-section steel trusses can be used in low-tower cable-stayed bridges with a tower-pier integrated and tower-beam separated structural system. However, if the bridge span increases and the bridge height is low, temperature forces will generate large secondary internal forces at the bridge towers, leading to difficulties in the design of the bridge towers and sub-foundations and poor engineering economics. Therefore, there is room for optimization in low-tower cable-stayed structural systems with a tower-pier integrated and tower-beam separated structural system.

[0010] In conclusion, it is necessary to propose new structural measures to overcome the shortcomings of existing technologies. Summary of the Invention

[0011] The purpose of this invention is to provide a structure for an irregularly shaped steel truss beam at the tower-beam connection and its construction method, so as to solve the problems of unreasonable stress and poor economy at the current tower-beam connection.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] The structure of the irregular steel truss at the tower-beam connection includes a bridge tower, a steel truss, and a bridge pier. The upper part of the steel truss is a highway bridge deck, and the lower part is a railway bridge deck. The steel truss includes an inverted trapezoidal section, a rectangular section, and an irregular transition section. The rectangular section is located above the bridge pier. The longitudinal sides of the rectangular section, from near to far, are the irregular transition section and the inverted trapezoidal section. The inverted trapezoidal section is connected to the bridge tower by a cable-stayed bridge.

[0014] The top of the rectangular section is the same width as the top of the inverted trapezoidal section, and the bottom width of the rectangular section is greater than the bottom width of the inverted trapezoidal section. The rectangular section is connected to the inverted trapezoidal section by the horizontal diagonal brace of the irregular transition section.

[0015] Furthermore, the inverted trapezoidal section includes two first straight web members, two first oblique support web members, and a first transverse brace;

[0016] Two first straight web members are vertically arranged between the transverse ends of the highway bridge deck and the railway bridge deck, respectively. Two first diagonal support web members are diagonally arranged between the transverse ends of the highway bridge deck and the transverse ends of the railway bridge deck, respectively. The first transverse brace is transversely arranged between the two first straight web members.

[0017] Furthermore, the rectangular section of the rectangular cross-section segment includes two second straight web members, two second diagonal support web members, two outer web members, two transverse beams, and one second transverse brace;

[0018] Two second straight web members are respectively vertically arranged between the transverse ends of the highway bridge deck and the railway bridge deck, two second diagonal support web members are respectively diagonally arranged between the transverse ends of the highway bridge deck and the transverse ends of the railway bridge deck, and the second transverse brace is transversely arranged between the two second straight web members.

[0019] The transverse beam is horizontally arranged on both sides of the railway bridge deck, and the outer web members are vertically arranged on both sides of the second diagonal support web members. The inner transverse end of the transverse beam is connected to the transverse end of the railway bridge deck and the bottom end of the second diagonal support web member. The top end of the outer web member is connected to the transverse end of the highway bridge deck and the top end of the second diagonal support web member. The outer transverse end of the transverse beam is connected to the bottom end of the outer web member.

[0020] Furthermore, the rectangular section of the rectangular cross-section also includes a longitudinal beam, which is located on both sides of the railway bridge deck and arranged horizontally and longitudinally. The outer end of the transverse beam and the bottom end of the outer web member are both connected to the longitudinal beam.

[0021] Furthermore, the longitudinal beam is located at the top of the pier, and the bottom of the bridge tower is connected downward to the longitudinal beam via the bridge tower vertical web members.

[0022] Furthermore, the top surface of the irregular transition section is rectangular and the bottom surface is trapezoidal, including the structure of the inverted trapezoidal cross-section section and the horizontal diagonal bar;

[0023] The horizontal diagonal brace is located on both sides of the railway bridge deck in the transverse direction. One end of the horizontal diagonal brace is connected to the longitudinal end of the longitudinal beam of the rectangular cross-section segment, and the other end of the horizontal diagonal brace is connected to the transverse end of the railway bridge deck of the inverted trapezoidal cross-section segment.

[0024] Furthermore, the rectangular cross-section segment includes a rectangular cross-section with at least three nodes.

[0025] Furthermore, the bottom end of the vertical web member of the bridge tower is also connected to the inner end of the transverse beam on both sides of its longitudinal direction by the horizontal diagonal brace.

[0026] Furthermore, the bottom end of the vertical web member of the bridge tower is supported by the bridge pier, and the outer web members on both sides of the bridge tower in the longitudinal direction are supported by the brackets beside the pier;

[0027] Both the pier and the bracket beside the pier are located on the top of the pier cap.

[0028] In addition, a construction method for the irregular steel truss girder structure at the tower-beam connection as described above is provided, the method comprising:

[0029] Construct a foundation;

[0030] Construct bridge piers on top of the pier cap;

[0031] Pier brackets are constructed on both longitudinal sides of the pier at the top of the pier cap;

[0032] A horizontal member extends from the bracket beside the pier and is connected and fixed to the pre-embedded part set in advance on the pier;

[0033] The rectangular section of the steel truss beam and the irregular transition section at the tower-beam connection point are assembled on the piers and the brackets beside the piers.

[0034] Construction begins simultaneously on the top of each pier. After the rectangular section and irregular transition section of the steel truss are assembled, the inverted trapezoidal section is assembled on both sides until the bridge is closed.

[0035] Remove the bracket next to the pier.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] This invention provides a unique steel truss girder structure and its construction method for the tower-girder connection. It employs a unique structural design combining an inverted trapezoidal cross-section (wider at the top and narrower at the bottom) with a rectangular cross-section. This design satisfies both the requirements of a dual-purpose road-rail bridge for different cross-sectional dimensions and the need for the steel truss girder to transmit the enormous axial forces at the bridge tower, resulting in a more rational use of structural materials and stress distribution. By varying the cross-section of the steel truss girder along the bridge length, and combining the inverted trapezoidal and rectangular cross-sections, it breaks through the traditional model of using a uniform cross-section for steel trusses in low-tower cable-stayed bridges, saving steel consumption in the main girder and achieving good economic efficiency. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0039] Figure 1 This is a structural diagram of the irregular steel truss beam at the connection between the tower and the beam.

[0040] Figure 2 This is an elevation view of the irregular steel truss beam structure at the connection between the tower and the beam.

[0041] Figure 3 This is a structural diagram of the upper, wider highway bridge deck at the connection between the tower and the beam.

[0042] Figure 4 This is a plan view of the narrower railway bridge deck at the connection between the tower and the beam.

[0043] Figure 5 It is a typical inverted trapezoidal cross-section of the steel truss beam at the tower-beam connection, which is wider at the top and narrower at the bottom.

[0044] Figure 6 It is a rectangular cross-section of the irregular steel truss beam with the same width at the top and bottom at the connection between the tower and the beam.

[0045] Figure 7 This is a top view of the irregularly shaped steel truss beam at the connection between the tower and the beam.

[0046] Figure 8 It is a cross-sectional view of the bridge tower, main beam and pier at the connection between the tower and the beam.

[0047] Figure 9 This is a schematic diagram illustrating the construction process using pier-side brackets, piers, and steel trusses to form a stable structure.

[0048] Figure 10 This is a structural diagram of a steel truss cable-stayed bridge with a low tower and beam structure constructed using the tower-beam consolidation and tower-pier separation system of this invention after construction is completed.

[0049] The diagram is labeled as follows:

[0050] 1-Bridge tower, 2-Steel truss, 3-Bridge pier, 4-Pile cap, 5-Pier side bracket;

[0051] 21-Inverted trapezoidal cross-section; 22-Rectangular cross-section;

[0052] 211-Highway bridge deck, 212-Railway bridge deck, 213-First straight web member, 214-First diagonal bracing web member, 215-First cross bracing;

[0053] 2121 - Horizontal diagonal brace, 2122 - Longitudinal beam, 2123 - Transverse beam;

[0054] 223 - Second straight web member, 224 - Second diagonal support web member, 225 - Second transverse link, 226 - Outer web member. Detailed Implementation

[0055] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0056] In the description of this invention, it should be understood that the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", "lateral", "longitudinal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0057] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection," "setting," etc., should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0058] Furthermore, in the description of this invention, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Of course, such terms can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in a sequence other than those illustrated or described herein.

[0059] It should also be noted that although the order of steps is mentioned in the method description, in some cases, steps may be performed in a different order than that described here, and this should not be interpreted as a restriction on the order of steps.

[0060] In a specific implementation, the direction of bridge length is defined as longitudinal, the direction perpendicular to bridge length is defined as transverse, the direction closer to the bridge centerline is defined as inside, and the direction farther from the bridge centerline is defined as outside.

[0061] This invention provides an irregularly shaped steel truss girder structure for the tower-beam connection. A rectangular cross-section structure is used at the bridge tower to optimize force transmission, while an inverted trapezoidal cross-section structure is used in other standard sections to reduce costs. A special irregularly shaped transition structure is designed to rationally and effectively connect sections with different cross-sectional structures. For example... Figure 1-4The structure includes a bridge tower 1, a steel truss 2, and a bridge pier 3. The upper part of the steel truss 2 is a highway bridge deck 211, and the lower part is a railway bridge deck 212, wider at the top and narrower at the bottom. The steel truss 2 includes an inverted trapezoidal section, a rectangular section, and an irregularly shaped transition section. The rectangular section is located above the bridge pier 3. The longitudinal sides of the rectangular section, from near to far, are the irregularly shaped transition section and the inverted trapezoidal section. A stay cable is installed between the inverted trapezoidal section and the bridge tower 1. The top of the rectangular section is the same width laterally as the top of the inverted trapezoidal section, while the bottom of the rectangular section is wider laterally than the bottom of the inverted trapezoidal section. The rectangular section is connected to the inverted trapezoidal section by a horizontal diagonal brace 2121 of the irregularly shaped transition section.

[0062] like Figure 5 The inverted trapezoidal section 21 includes two first straight web members 213, two first diagonal support web members 214, and one first transverse brace 215. The two first straight web members 213 are vertically arranged between the transverse ends of the highway bridge deck 211 and the railway bridge deck 212, respectively. The two first diagonal support web members 214 are diagonally arranged between the transverse ends of the highway bridge deck 211 and the transverse ends of the railway bridge deck, respectively. The first transverse brace 215 is transversely arranged between the two first straight web members 213.

[0063] like Figure 6 The rectangular section 22 of the rectangular cross-section segment includes two second straight web members 223, two second diagonal bracing web members 224, two outer web members 226, two transverse beams 2123, and a second transverse brace 225. The two second straight web members 223 are vertically arranged between the transverse ends of the highway bridge deck 211 and the railway bridge deck 212, respectively. The two second diagonal bracing web members 224 are diagonally arranged between the transverse ends of the highway bridge deck 211 and the transverse ends of the railway bridge deck, respectively. The second transverse brace 225 is transversely arranged between the two second straight web members 223. The transverse beam 2123 is horizontally arranged on both sides of the railway bridge deck 212, and the outer web member 226 is vertically arranged on both sides of the second diagonal support web member 224. The inner transverse end of the transverse beam 2123 is connected to the transverse end of the railway bridge deck 212 and the bottom end of the second diagonal support web member 224. The top end of the outer web member 226 is connected to the transverse end of the highway bridge deck 211 and the top end of the second diagonal support web member 224. The outer transverse end of the transverse beam 2123 is connected to the bottom end of the outer web member 226.

[0064] like Figure 7 The rectangular section 22 of the rectangular cross-section segment also includes longitudinal beams 2122, which are located on both sides of the railway bridge deck 212 and arranged horizontally in the longitudinal direction. The outer ends of the transverse beams 2123 and the bottom ends of the outer web members 226 are both connected to the longitudinal beams 2122. The longitudinal beams 2122 are located on the top of the piers 3, and the bridge tower 1 is connected downward to the longitudinal beams 2122 through the vertical web members of the bridge tower.

[0065] like Figure 3 and Figure 7 The top surface of the irregular transition section is rectangular, and the bottom surface is trapezoidal, including the structure of the inverted trapezoidal cross-section section and the horizontal diagonal brace 2121. The horizontal diagonal brace 2121 is located on both sides of the railway bridge deck 212 in the transverse direction. One end of the horizontal diagonal brace 2121 is connected to the longitudinal end of the longitudinal beam 2122 of the rectangular cross-section section, and the other end of the horizontal diagonal brace 2121 is connected to the transverse end of the railway bridge deck 212 of the inverted trapezoidal cross-section section.

[0066] like Figure 1-10 In this embodiment, the rectangular cross-section segment includes a rectangular cross-section 22 with three nodes, which can extend several bays to both sides of the bridge tower or pier as appropriate according to the force. The transition can be achieved in one bay or through two bays. Horizontal diagonal braces 2121 are also connected between the bottom end of the vertical web members of the bridge tower and the inner ends of the transverse beams 2123 on both sides of its longitudinal direction. The bottom end of the bridge tower 1 is supported by the pier 3, and the outer web members 226 on both sides of the longitudinal direction of the bridge tower 1 are supported by the pier side brackets 5. The pier 3 and the pier side brackets 5 are both located on the top of the pier cap 4.

[0067] Along the length of the bridge, the cross-section changes from a typical inverted trapezoid to a rectangular cross-section at the tower-beam connection, and then back to a typical inverted trapezoid. The outer contour projection of the irregular transition section can be trapezoidal, rectangular, or triangular.

[0068] The cross-section of steel truss girder 2 is replaced by an inverted trapezoidal cross-section with a rectangular cross-section of equal width at both the top and bottom. A horizontal diagonal brace is installed between the inverted trapezoidal and rectangular sections to create a transition from the inverted trapezoidal to the rectangular cross-section. This overcomes the shortcomings of traditional inverted trapezoidal cross-sections, which prevent the use of a fixed tower-beam structure or a separate tower-pier structure in low-tower cable-stayed bridges, or the problem of having an excessively wide and uneconomical railway bridge deck for dual-purpose road and rail bridges, which can only use rectangular cross-sections. Tower 1 is directly connected to the tower's vertical web members on the same plane as the main truss. The enormous axial force borne by tower 1 is rapidly transferred to the lower chord node through the tower's vertical web members, and finally to the foundation through the supports and piers 3, avoiding secondary distribution of the enormous axial force within the cross-section of steel truss girder 2.

[0069] A rectangular section with the same width at the top and bottom is set at the steel truss section connecting the tower and the beam. At the same time, in order to make the force more uniform, one or two rectangular sections are set in the first or second section on both sides of the bridge tower 1. Between the inverted trapezoidal section and the rectangular section in the standard section, a diagonal bar is added to the outside of the lower chord of the lower railway bridge deck to connect with the rectangular section, so as to form a smooth transition along the axial force of the bridge and the transition of the section.

[0070] The steel truss members in the structure of this invention are all made of bridge steel, and the cross sections are either I-shaped or box-shaped depending on the stress. The members can be connected to each other by bolts through gusset plates.

[0071] The construction method for the irregular steel truss girder structure at the tower-beam connection mentioned above specifically includes the following steps:

[0072] S1: Construct foundation 4;

[0073] S2: Construct pier 3 on top of pier cap 4;

[0074] S3: Construct pier side brackets 5 on both longitudinal sides of pier 3 at the top of pier cap 4;

[0075] S4: A horizontal member extends from the pier side bracket 5 and is connected and fixed to the pre-embedded part set in advance on the pier 3 to ensure that the pier side bracket 5 has sufficient rigidity and stability;

[0076] S5: Start assembling the rectangular section of the steel truss beam and the irregular transition section at the tower-beam connection on pier 3 and pier-side bracket 5;

[0077] S6: Construction begins simultaneously on the top of each pier 3. After the rectangular section and irregular transition section of the steel truss are assembled, the inverted trapezoidal section is assembled on both sides until the bridge is closed.

[0078] S7: Remove bracket 5 next to the pier.

[0079] In the above method, the pier-side brackets are set on both sides of the pier at the connection between the bridge tower and the main beam. After the rectangular section is assembled, the inverted trapezoidal steel truss beam is cantilevered and assembled along the length of the bridge. This method effectively improves the stability and safety of the main beam during construction.

[0080] This invention uses irregularly shaped structures to transition and connect steel truss beams with different cross-sections, which has the following advantages:

[0081] 1) This invention adopts a combination of an inverted trapezoidal cross section that is wider at the top and narrower at the bottom and a rectangular cross section, which not only meets the requirements of the dual-purpose road and rail bridge for different cross section sizes, but also meets the requirements of the steel truss girder for transmitting huge axial forces at the bridge tower, making the use of structural materials and stress more reasonable.

[0082] 2) The present invention uses an inverted trapezoidal cross-section that is wider at the top and narrower at the bottom to smoothly transfer the axial force of the main steel truss of the low-tower cable-stayed bridge to the rectangular cross-section at the bridge tower by setting a transition section, thus realizing a smooth connection of force flow at the variable cross-section along the bridge length.

[0083] 3) The traditional inverted trapezoidal cross section of the bridge tower is designed as a rectangular cross section at the bridge tower of this invention. This can effectively transfer the axial force of the bridge tower of the low-tower cable-stayed bridge, which is a tower-beam fixed and tower-pier separated system, out of the main truss structure. This shortens the force transmission path and makes it possible for the steel truss beam to adopt an inverted trapezoidal cross section and the structure to adopt a tower-beam fixed and tower-pier separated system, thus enriching the shape of the bridge structure.

[0084] 4) This invention adopts the variation of the cross section of the steel truss along the length of the bridge. By combining the inverted trapezoidal cross section and the rectangular cross section, it breaks through the traditional mode of using a uniform cross section for the steel truss of the low tower cable-stayed bridge, saves the amount of steel used in the main beam, and has good economic efficiency.

[0085] 5) The construction method provided by this invention involves setting up a pier-side bracket next to the pier to temporarily fix the main truss (which is fixed to the tower and beam and separate from the tower and pier) to the pier and the pier-side bracket, forming a stable load-bearing structure. Then, relying on the erected rectangular cross-section steel truss beam, the first inverted trapezoidal section is assembled sequentially, connecting the members between the inverted trapezoidal section and the rectangular section. Finally, the other inverted trapezoidal sections are assembled sequentially, with each pier being constructed simultaneously, and the structure is finally closed. The construction process exhibits high structural stability, safety, and economy.

[0086] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A special-shaped steel truss structure at the tower-beam connection, the structure comprising a bridge tower (1), a steel truss (2), and a bridge pier (3), characterized in that: The upper part of the steel truss (2) is a highway bridge deck (211), and the lower part is a railway bridge deck (212). The steel truss (2) includes an inverted trapezoidal section, a rectangular section, and an irregular transition section. The rectangular section is located above the bridge pier (3). The longitudinal sides of the rectangular section are the irregular transition section and the inverted trapezoidal section from near to far. The inverted trapezoidal section is connected to the bridge tower (1) by a cable-stayed cable. The top of the rectangular section is the same width as the top of the inverted trapezoidal section, and the bottom width of the rectangular section is greater than the bottom width of the inverted trapezoidal section. The rectangular section is connected to the inverted trapezoidal section by the horizontal diagonal bar (2121) of the irregular transition section. The inverted trapezoidal section (21) of the inverted trapezoidal section includes two first straight web members (213), two first oblique support web members (214), and a first transverse bracing (215). Two first straight web members (213) are respectively vertically arranged between the lateral ends of the highway bridge deck (211) and the railway bridge deck (212), two first diagonal support web members (214) are respectively diagonally arranged between the lateral ends of the highway bridge deck (211) and the lateral ends of the railway bridge deck, and the first transverse bracing (215) is arranged transversely between the two first straight web members (213); The rectangular section (22) of the rectangular section includes two second straight web members (223), two second diagonal support web members (224), two outer web members (226), two transverse beams (2123), and a second transverse bracing (225). Two second straight web members (223) are respectively vertically arranged between the lateral ends of the highway bridge deck (211) and the railway bridge deck (212), two second diagonal support web members (224) are respectively diagonally arranged between the lateral ends of the highway bridge deck (211) and the lateral ends of the railway bridge deck, and the second transverse bracing (225) is arranged transversely between the two second straight web members (223); The transverse beam (2123) is horizontally arranged on both sides of the railway bridge deck (212), and the outer web member (226) is vertically arranged on both sides of the second diagonal support web member (224). The inner transverse end of the transverse beam (2123) is connected to the transverse end of the railway bridge deck (212) and the bottom end of the second diagonal support web member (224). The top end of the outer web member (226) is connected to the transverse end of the highway bridge deck (211) and the top end of the second diagonal support web member (224). The outer transverse end of the transverse beam (2123) is connected to the bottom end of the outer web member (226).

2. The irregular steel truss girder structure at the tower-beam connection according to claim 1, characterized in that: The rectangular section (22) of the rectangular section also includes a longitudinal beam (2122), which is located on both sides of the railway bridge deck (212) and arranged horizontally and longitudinally. The outer end of the transverse beam (2123) and the bottom end of the outer web member (226) are both connected to the longitudinal beam (2122).

3. The irregular steel truss girder structure at the tower-beam connection according to claim 2, characterized in that: The longitudinal beam (2122) is located on the top of the pier (3), and the bottom of the bridge tower (1) is connected downward to the longitudinal beam (2122) through the bridge tower vertical web members.

4. The irregular steel truss beam structure at the tower-beam connection according to claim 3, characterized in that: The top surface of the irregular transition section is rectangular and the bottom surface is trapezoidal, including the structure of the inverted trapezoidal cross-section section and the horizontal diagonal bar (2121). The horizontal diagonal brace (2121) is located on both sides of the railway bridge deck (212). One end of the horizontal diagonal brace (2121) is connected to the longitudinal end of the longitudinal beam (2122) of the rectangular cross-section section, and the other end of the horizontal diagonal brace (2121) is connected to the transverse end of the railway bridge deck (212) of the inverted trapezoidal cross-section section.

5. The irregular steel truss beam structure at the tower-beam connection according to claim 4, characterized in that: The rectangular cross-section segment includes a rectangular cross-section with at least three nodes (22).

6. The irregular steel truss beam structure at the tower-beam connection according to claim 5, characterized in that: The bottom end of the vertical web member of the bridge tower is also connected to the inner end of the transverse beam (2123) on both sides of its longitudinal direction by the horizontal diagonal member (2121).

7. The irregular steel truss beam structure at the tower-beam connection according to claim 6, characterized in that: The bottom end of the vertical web members of the bridge tower is supported by the bridge pier (3), and the outer web members (226) on both sides of the longitudinal direction of the bridge tower (1) are supported by the pier bracket (5). The pier (3) and the bracket (5) beside the pier are both located on top of the pier cap (4).

8. The construction method of the irregular steel truss beam structure at the tower-beam connection as described in claim 7, characterized in that: The method includes: Construct the foundation (4); A pier (3) is constructed on top of the pier cap (4); Pier brackets (5) are installed on both sides of the pier (3) at the top of the pier cap (4). A transverse member extends from the bracket (5) next to the pier and is connected and fixed to the pre-embedded part set in advance on the pier (3); On the pier (3) and the bracket (5) next to the pier, the rectangular section of the steel truss beam and the irregular transition section at the tower beam connection point are assembled. Construction begins simultaneously on the top of each pier (3). After the rectangular section of the steel truss beam and the irregular transition section are assembled, the inverted trapezoidal section is assembled on both sides until the bridge is closed. Remove the bracket next to the pier (5).

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