A cantilever pier capping beam using a stiffening skeleton and its design method

Abstract

The present invention discloses a cantilever pier capping beam with a stiffening skeleton and its design method, which includes a capping beam body, a stiffening skeleton, distribution steel bars and concrete; the stiffening skeleton is arranged inside the capping beam body, the distribution steel bars are arranged outside the stiffening skeleton, and the concrete is formed by prefabrication or in-situ casting; the stiffening skeleton includes main truss members and horizontal bracings, the two rows of main truss members are juxtaposed and connected by a number of horizontally arranged horizontal bracings; each row of main truss members includes a number of upper chord members, lower chord members and web members, the upper chord members are arranged at the top of the capping beam body, the lower chord members are arranged at the bottom of the capping beam body, and two adjacent web members and the upper chord member or the lower chord member form a triangular structure; the present invention uses the stiffening skeleton as the main force-bearing body, fully exerts the combined force-bearing effect of steel and concrete, the structural force transmission mechanism is clear, and the calculation is convenient; the stiffening skeleton is welded and formed in the factory, the overall hoisting and positioning are fast, and the structural reinforcement is less, which is conducive to the dense pouring of concrete.

Description

Technical Field

[0001] The present invention belongs to the technical field of bridge engineering, and specifically discloses a cantilever pier capping beam using a stiffening skeleton and a design method thereof. Background Art

[0002] In bridge engineering, piers with cantilever capping beams have been widely used in urban viaducts, rail transit bridges, and highway bridges due to their advantages such as large under-bridge passage space, beautiful appearance, and clear vision.

[0003] Currently, for the reinforcement design in the cantilever capping beam of a pier, a steel reinforcement cage formed by binding longitudinal steel bars and closely spaced stirrups is mostly used. For such a capping beam reinforcement structure, the production efficiency of the steel reinforcement cage is relatively low, and its own stiffness is poor. The flexural and shear bearing capacities of the reinforced concrete capping beam are relatively low, and generally, a large number of prestressing tendons need to be configured. Therefore, how to improve the reinforcement structure of the cantilever capping beam to both improve the construction production efficiency and enhance the bearing capacity of the structure is a technical problem that needs to be solved in the design of the cantilever capping beam. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a design scheme for a cantilever pier capping beam using a stiffening skeleton in view of the above-mentioned deficiencies of the prior art, replacing the traditional densely arranged steel reinforcement cage with a welded integral stiffening skeleton, thereby improving the mechanical rationality and construction production efficiency of the cantilever capping beam.

[0005] To solve the above technical problem, the technical solution adopted by the present invention is:

[0006] A cantilever pier capping beam using a stiffening skeleton includes a capping beam body, a stiffening skeleton, distribution steel bars, and concrete; the stiffening skeleton is arranged inside the capping beam body, the distribution steel bars are arranged outside the stiffening skeleton, and the concrete is formed by prefabrication or in-situ casting; the stiffening skeleton includes main truss members and horizontal bracings, two rows of main truss members are arranged side by side and connected by a plurality of horizontally arranged horizontal bracings; each row of main truss members includes a plurality of upper chord bars, lower chord bars, and web members, the upper chord bars are arranged at the top of the capping beam body, the lower chord bars are arranged at the bottom of the capping beam body, the two ends of the web members are respectively connected to the upper chord bars and the lower chord bars, and adjacent two web members and the upper chord bar or the lower chord bar form a triangular structure.

[0007] As a further preference of the present invention, it includes a plurality of bearing pads, which are distributed above the capping beam body; the connection between the web member and the upper chord bar is an upper chord node, the connection between the web member and the lower chord bar is a lower chord node, and the upper chord node is arranged directly below the bearing pad.

[0008] As a further preference of the present invention, the upper chord bar and the lower chord bar have a double I-beam section, and the web member and the horizontal bracing have an I-beam section.

[0009] As a further preference of the present invention, the web members are arranged in pairs, and at the upper chord joints or lower chord joints, the webs of each pair of web members correspond to the double webs of the upper chord member or the lower chord member.

[0010] As a further preference of the present invention, the lateral bracing connects the upper chord joints or lower chord joints of two rows of main truss members.

[0011] As a further preference of the present invention, the connection between the web members and the upper chord member and the lower chord member is by welding, and the connection between the lateral bracing and the upper chord joint or the lower chord joint is by welding.

[0012] A design method for a cantilever pier capping beam using a stiffening skeleton includes the following key points:

[0013] Key point 1: The stiffening skeleton concrete capping beam can be designed according to the steel-concrete composite structure. The upper chord joints of the stiffening skeleton are arranged at the support positions of the bridge span main girders, so that the concentrated force is directly transmitted to the stiffening skeleton; the upper and lower chord members bear the bending moment, and the web members transmit the shear force, making the force mechanism of the capping beam clear and the bearing capacity higher.

[0014] Key point 2: Since the stiffening skeleton bears the main load transmitted from the upper structure, a small amount of structural reinforcement is required around the stiffening skeleton to prevent concrete shrinkage and temperature cracks; when the unilateral cantilever of the capping beam is relatively long (for example, more than 5 m), prestressing tendons need to be configured to improve the crack resistance.

[0015] Key point 3: The configuration of the stiffening skeleton is preferably a triangular truss without a vertical rod or a right-angled triangular truss, and the included angle between the tension members and the compression members in the main truss of the stiffening skeleton is not less than 25°.

[0016] Key point 4: For the analysis of the vertical displacement at the cantilever end of the stiffening skeleton concrete capping beam, the participation of the concrete part around the main truss members in the work can be considered, and the calculation is carried out according to the virtual work principle as follows:

[0017]

[0018] Where: EA i = E c A ci + E s A si ,A i = A ci + A si ,

[0019] In the above calculation formula: f is the deflection at the cantilever end; is the axial force of the i-th combined member when acting at the distal support position, with tension being positive and compression being negative; N i is the reaction force of the upper structure P1, P2,..., P​​​m Under the action, the axial force of the i-th combined member is positive in tension and negative in compression; L i is the length of the i-th combined member; EA i is the axial stiffness of the i-th combined member; E c is the elastic modulus of the concrete around the combined member; A ci is the effective cross-sectional area of the concrete around the i-th combined member. When the combined member is in tension, the effect of the concrete is ignored; E s is the elastic modulus of the steel skeleton of the combined member; A si is the cross-sectional area of the steel skeleton of the i-th combined member; k is the coefficient of the degree of participation of the concrete around the combined member in the work. The combined member is a combined structure formed by each upper chord, lower chord or web member and the surrounding concrete.

[0020] As a further preference of the present invention, the axial force of each member in the main truss can be obtained through the structural mechanics calculation diagram, where the compressive members consider the partial participation of the surrounding concrete in the work, and the tensile members ignore the effect of the surrounding concrete.

[0021] Key point 5: The design value of the bearing capacity of the combined member of the stiffened frame concrete capping beam can be calculated according to the following formula:

[0022]

[0023] In the formula: N cu,i is the design value of the compressive bearing capacity of the i-th combined member; N tu,i is the design value of the tensile bearing capacity of the i-th combined member; f ci is the design value of the compressive strength of the concrete around the i-th combined member; f si is the design value of the strength of the steel skeleton of the i-th combined member; is the stability coefficient of the i-th combined member under axial compression, and is taken according to the following table:

[0024]

[0025]

[0026]

[0027] Note: l′ is the calculated length of the member; i′ is the radius of gyration of the cross-section of the combined member; I c is the equivalent cross-sectional moment of inertia of the concrete around the combined member, I s is the moment of inertia of the steel skeleton.

[0028] Key point 6: Preferably, the full stress criterion can be adopted to optimize the cross-section design of the main truss members. At this time, the axial stress of each main truss member is set to be equal to the allowable stress of the material, i.e., σ = N i / A i = [σ]. At this time, the deflection of the cantilever end of the capping beam can be calculated by the following formula:

[0029]

[0030] In the formula: [σ] is the allowable stress of each main truss member.

[0031] The present invention has the following beneficial effects:

[0032] (1) Compared with the commonly used reinforced concrete capping beams at present, the combined stress-bearing effect of steel and concrete can be fully exerted.

[0033] (2) Using the stiffening skeleton as the main stress-bearing body, the force transmission mechanism of the structure is clear and the structure calculation is convenient.

[0034] (3) The capping beam with a stiffening skeleton has high work efficiency: it is formed by welding in the factory, and the overall hoisting and positioning are fast, with good economy.

[0035] (4) The capping beam has less structural reinforcement, which is beneficial to the dense pouring of concrete. Description of the Drawings

[0036] Figure 1 is a perspective view of the cantilever pier capping beam with a stiffening skeleton of the present invention;

[0037] Figure 2 is a front view of the cantilever pier capping beam with a stiffening skeleton of the present invention;

[0038] Figure 3 is a top view of the cantilever pier capping beam with a stiffening skeleton of the present invention;

[0039] Figure 4 is a perspective view of the structure of the stiffening skeleton of the present invention;

[0040] Figure 5 is Figure 4 an enlarged schematic view of the middle node section a in

[0041] Figure 6 is the calculation diagram of the capping beam of the stiffening skeleton concrete under the action of the reaction forces P1, P2,..., P m of the superstructure;

[0042] Figure 7 is the calculation diagram of the capping beam of the stiffening skeleton concrete when the virtual force P = 1 acts on the far-end support;

[0043] Figure 8Perspective view of the structural steel stiffening skeleton with a right-angled triangular truss configuration

[0044] In the figure, 100 - steel stiffening skeleton, 101 - bearing padstone, 102 - concrete, 1 - main truss panel, 2 - lateral bracing, 1.1 - upper chord, 1.2 - lower chord, 1.3 - web member, 1.4 - upper chord joint, 1.5 - lower chord joint. Specific implementation mode

[0045] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific preferred implementation modes.

[0046] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "left side", "right side", "upper part", "lower part", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. "No. 1", "No. 2", etc. do not represent the importance of the components, so it cannot be understood as a limitation to the present invention. The specific dimensions adopted in this embodiment are only for illustrating the technical solution by way of example and do not limit the protection scope of the present invention.

[0047] As Figures 1-3 shown, a cantilever pier capping beam using a steel stiffening skeleton 100 includes a capping beam body, a steel stiffening skeleton 100, distribution steel bars, and concrete 102. The steel stiffening skeleton 100 is arranged inside the capping beam body, the distribution steel bars are arranged outside the steel stiffening skeleton 100, and the concrete 102 is formed by precast or cast-in-place.

[0048] As Figure 4 shown, the steel stiffening skeleton 100 includes main truss panels 1 and lateral bracings 2. Two rows of main truss panels 1 are juxtaposed and connected by a number of laterally braced 2 arranged in parallel. The center line of the main truss panel 1 is consistent with the center line of the capping beam bearing in the transverse bridge direction. Each row of main truss panels 1 includes a number of upper chords 1.1, lower chords 1.2, and web members 1.3. The upper chords 1.1 and lower chords 1.2 are respectively arranged at the top and bottom of the capping beam body and mainly play a bending resistance role. Both ends of the web member 1.3 are respectively connected to the upper chord 1.1 and the lower chord 1.2. Adjacent two web members 1.3 and the upper chord 1.1 or the lower chord 1.2 form a triangle to form a planar stable structure.

[0049] As Figures 2-5 shown, there are multiple bearing padstones 101, which are distributed above the capping beam body. The connection point of the web member 1.3 and the upper chord 1.1 is the upper chord joint 1.4, and the connection point of the web member 1.3 and the lower chord 1.2 is the lower chord joint 1.5. To ensure the clear force transmission path of the capping beam and the direct force bearing of the steel stiffening skeleton, the upper chord joint 1.4 should be arranged directly below the bearing padstone 101, and the position of the lower chord joint 1.5 is not limited.

[0050] AsFigures 4-5 As shown, the upper chord member 1.1 and the lower chord member 1.2 are double I-section steel girders, that is, double-web steel girders, and the web members 1.3 and the horizontal bracing 2 adopt I-section steel girders. In this example, it is preferred that the web members 1.3 are arranged in pairs, and at the upper chord node 1.4 or the lower chord node 1.5, the webs of each pair of web members 1.3 should correspond to the double-web positions of the upper chord member 1.1 or the lower chord member 1.2, and the force transmission mechanism is simple and clear.

[0051] As Figures 4-5 shown, the horizontal bracing 2 is an I-section steel girder, which connects the upper chord nodes 1.4 or the lower chord nodes 1.5 of two rows of main truss members 1 to form a space-stable structure and ensure the coordinated operation of each row of main truss members 1.

[0052] Figure 6 For the support reactions P1, P2,..., P of the superstructure m acting, the calculation diagram of the cantilever pier cap beam with the stiffening skeleton 100 is shown. According to this diagram, the axial force of each member can be calculated. Among them, for the compression members, the surrounding concrete 102 is considered to participate in the work partially, and for the tension members, the effect of the surrounding concrete 102 is ignored. Figure 6 The shaded part around the compression member in the figure represents the concrete 102 participating in the force; Figure 7 is the calculation diagram of the cantilever pier cap beam with the stiffening skeleton 100 when the virtual force P = 1 acts on the far-end support. Combining Figure 6 and Figure 7 the vertical displacement of the cantilever end of the pier cap beam can be calculated.

[0053] Next, the design method of the cantilever pier cap beam with the stiffening skeleton 100 will be elaborated in detail in combination with the embodiments:

[0054] Key point 1: The cantilever pier cap beam with the stiffening skeleton 100 can be designed according to the steel-concrete composite structure. The upper chord node 1.4 of the stiffening skeleton 100 is arranged at the support position of the bridge-span main beam, so that the concentrated force is directly transmitted to the stiffening skeleton 100; the upper chord member 1.1 and the lower chord member 1.2 bear the bending moment, and the web members 1.3 transmit the shear force, making the force transmission mechanism of the pier cap beam clear and the bearing capacity higher.

[0055] Key point 2: Since the stiffening skeleton 100 bears the main load transmitted from the superstructure, a small amount of structural reinforcement is required around the stiffening skeleton 100 to prevent shrinkage and temperature cracks of the concrete 102; when the single-side cantilever of the pier cap beam is relatively long (for example, more than 5 m), prestressed tendons need to be arranged to improve the crack resistance.

[0056] Key Point 3: The configuration of the stiffening skeleton 100 is preferably a triangular truss without vertical bars or a right-angled triangular truss, and the angle between the tension member and the compression member in the main truss panel 1 of the stiffening skeleton 100 is not less than 25°. When the angle between the tension bar and the compression bar is too small, the configuration of the stiffening skeleton 100 will be unreasonable, and its members will deviate greatly from the true force flow transmission path. Therefore, this specification requires a range for the compression members and tension members of the stiffening skeleton 100, but the specific values need to be determined in combination with actual cases.

[0057] Key Point 4: For the analysis of the vertical displacement of the cantilever end of the cantilever pier capping beam with the stiffening skeleton 100, the partial participation of the concrete 102 around each member of the main truss panel 1 can be considered, and the calculation is carried out according to the following formula based on the principle of virtual work:

[0058]

[0059] Among them: EA i = E c A ci + E s A si ,A i = A ci + A si ,

[0060] In the above calculation formula: f is the deflection of the cantilever end; is the axial force of the i-th combined member when acting on the position of the far-end support, with tension being positive and compression being negative; N i is the axial force of the i-th combined member under the action of the upper structure support reactions P1, P2,..., P m with tension being positive and compression being negative; L i is the length of the i-th combined member; EA i is the axial stiffness of the i-th combined member; E c is the elastic modulus of the concrete 102 around the combined member; A ci is the effective cross-sectional area of the concrete 102 around the i-th combined member; E s is the elastic modulus of the steel skeleton of the combined member; A si is the cross-sectional area of the steel skeleton of the i-th combined member; k is the coefficient of the participation degree of the concrete 102 around the combined member. The combined member is a combined structure formed by each upper chord 1.1, lower chord 1.2 or web member 1.3 and the surrounding concrete 102. In this formula, except for f, the other quantities are known quantities. Among them, the elastic modulus value can be obtained by querying relevant specifications, and the other variables can be obtained through existing calculation methods.

[0061] As a further preference of the present invention, the axial force of each member in the main truss can be obtained through the structural mechanics calculation diagram. For the compression members, the surrounding concrete part is considered to participate in the work, and for the tension members, the effect of the surrounding concrete is ignored.

[0062] Key point 5: For the design value of the bearing capacity of the combined members of the cantilever pier capping beam using the stiffening skeleton 100, it can be calculated according to the following formula:

[0063]

[0064] In the formula: N cu,i is the design value of the compressive bearing capacity of the i-th combined member; N tu,i is the design value of the tensile bearing capacity of the i-th combined member; f ci is the design value of the compressive strength of the concrete 102 around the i-th combined member; f si is the design value of the strength of the steel skeleton of the i-th combined member; is the stability coefficient of the i-th combined member under axial compression, and it is taken according to the following table:

[0065]

[0066]

[0067] Note: l′ is the calculated length of the member; i′ is the radius of gyration of the cross-section of the combined member; I c is the equivalent cross-section moment of inertia of the concrete 102 around the combined member, I s is the moment of inertia of the steel skeleton cross-section. In this formula, except for N cu,i , N tu,i , the rest of the quantities are known quantities. Among them, the values of the elastic modulus and the rules for taking the calculated length can be obtained by querying relevant specifications, and the rest of the variables can be obtained by existing calculation methods.

[0068] Key point 6: As a preference, the cross-section design of the members of the main truss 1 can be optimized by using the full stress criterion. At this time, the axial stress of each member of the main truss 1 is made equal to the allowable stress of the material, that is, σ = N i / A i = [σ]. At this time, the deflection of the capping beam cantilever end can be calculated according to the following formula:

[0069]

[0070] In the formula: [σ] is the allowable stress value of each member of the main truss 1.

[0071] According to the above formula, it can be known that if the minimum deflection of the cantilever end is taken as the goal, then only the shortest force transmission path is required, that is, when a unit force acts on the far-end support, the axial force of each combined member and the length L of the combined memberi The sum of the absolute values of the products is minimized.

[0072] As Figure 8 shown, preferably, the stiffening skeleton 100 can also be selected as a right-angled triangular truss configuration.

[0073] The present invention also provides a construction method for a cantilever pier capping beam using the stiffening skeleton 100, which specifically includes the following steps:

[0074] Step 1: Carry out the design work of the stiffening skeleton 100, optimize the cross-sectional dimensions of the members, and check the strength of the members and the deflection of the cantilever end;

[0075] Step 2: Fabricate the upper chord 1.1, lower chord 1.2, and web members 1.3 in the factory and weld them to form the main truss panel 1, and weld the main truss panels 1 through the horizontal bracing 2 to form the stiffening skeleton 100;

[0076] Step 3: Conduct flaw detection on the welding quality of the stiffening skeleton 100 to ensure the integrity, reliability, safety, and usability of the stiffening skeleton 100;

[0077] Step 4: Erect the scaffold and the formwork for pouring the concrete 102, and transport the stiffening skeleton 100 to the construction site;

[0078] Step 5: Hoist and position the stiffening skeleton 100, tie the structural steel bars, and connect them to the longitudinal bars of the pier to form an integral stressed steel skeleton;

[0079] Step 6: Horizontally layer by layer and longitudinally segment by segment pour the concrete 102, cure the concrete 102, and remove the scaffold and formwork after the strength reaches the design requirements.

[0080] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A design method for a cantilever pier capping beam using a stiffening skeleton, characterized in that: The cantilever pier capping beam includes a capping beam body, a stiffening skeleton (100), distribution steel bars, and concrete (102); The stiffening skeleton (100) is arranged inside the capping beam body, the distribution steel bars are arranged outside the stiffening skeleton (100), and the concrete (102) is formed by precast or cast-in-place; the stiffening skeleton (100) includes main truss girders (1) and horizontal bracings (2), the two rows of main truss girders (1) are juxtaposed and connected by a number of horizontally arranged horizontal bracings (2); each row of main truss girders (1) includes a number of upper chord members (1.1), lower chord members (1.2), and web members (1.3), the upper chord members (1.1) are arranged at the top of the capping beam body, the lower chord members (1.2) are arranged at the bottom of the capping beam body, the two ends of the web members (1.3) are respectively connected to the upper chord members (1.1) and the lower chord members (1.2), and adjacent two web members (1.3) and the upper chord member (1.1) or the lower chord member (1.2) form a triangular structure; the design method of the cantilever pier capping beam includes the following key points: Key point 1: The capping beam is designed according to the steel-concrete composite structure, and the upper chord nodes (1.4) of the stiffening skeleton (100) are arranged at the position of the bearing pad stones (101) of the bridge span main girder, so that the concentrated force is directly transmitted to the stiffening skeleton (100); the upper chord members (1.1) and the lower chord members (1.2) bear the bending moment, and the web members (1.3) transmit the shear force, so that the force-bearing mechanism of the capping beam is clear and the bearing capacity is higher; Key point 2: Since the stiffening skeleton (100) bears the main load transmitted from the upper structure, a small amount of structural reinforcement is required around the stiffening skeleton (100) to prevent shrinkage and temperature cracks of the concrete (102); when the unilateral cantilever of the capping beam is greater than 5 meters, prestressed tendons are arranged around the stiffening skeleton (100) to improve the crack resistance; Key point 3: The configuration of the stiffening skeleton (100) is a triangular truss without vertical bars or a right-angled triangular truss, and the degree of each angle of the triangular structure in the main truss girder (1) of the stiffening skeleton (100) is greater than or equal to 25°; Key point 4: For the analysis of the vertical displacement at the cantilever end of the capping beam, considering that the concrete (102) part around each member of the main truss girder (1) participates in the work, the calculation is carried out according to the following formula based on the principle of virtual work: Where: EA i = E c A ci + E s A si , A i = A ci + A si , k = E s / E c In the above calculation formula: f is the deflection at the cantilever end; is When acting on the position of the far-end support, the axial force of the i-th combined member, tensile is positive and compressive is negative; N i is the reaction forces P1, P2,..., P m of the superstructure acting on the axial force of the i-th combined member, tensile is positive and compressive is negative; L i is the length of the i-th combined member; EA i is the axial stiffness of the i-th combined member; E c is the elastic modulus of the surrounding concrete (102) of the combined member; A ci is the effective cross-sectional area of the surrounding concrete (102) of the i-th combined member. When the combined member is in tension, the effect of the concrete (102) is ignored; E s is the elastic modulus of the steel skeleton of the combined member; A si is the cross-sectional area of the steel skeleton of the i-th combined member; k is the coefficient of the participation degree of the surrounding concrete (102) of the combined member; The combined member is a combined structure formed by each upper chord (1.1), lower chord (1.2) or web member (1.3) and the surrounding concrete (102).

2. The design method of a cantilever pier capping beam using a stiffening skeleton according to claim 1, characterized in that: It also includes a number of bearing pad stones (101), which are distributed above the capping beam body; the connection between the web member (1.3) and the upper chord member (1.1) is the upper chord node (1.4), the connection between the web member (1.3) and the lower chord member (1.2) is the lower chord node (1.5), and the upper chord node (1.4) is arranged directly below the bearing pad stone (101).

3. The design method of a cantilever pier capping beam adopting a stiffening skeleton according to claim 2, characterized in that: The upper chord member (1.1) and the lower chord member (1.2) are of double I-beam cross-section, and the web member (1.3) and the horizontal bracing (2) are of I-beam cross-section.

4. The design method of a cantilever pier capping beam using a stiffening skeleton according to claim 3, characterized in that: The web members (1.3) are arranged in pairs, and at the upper chord node (1.4) or the lower chord node (1.5), the webs of each pair of web members (1.3) correspond to the double webs of the upper chord member (1.1) or the lower chord member (1.2).

5. The design method of a cantilever pier capping beam adopting a stiffening skeleton according to claim 2, characterized in that: The horizontal bracing (2) connects the upper chord nodes (1.4) or the lower chord nodes (1.5) of the two rows of main truss girders (1).

6. The design method of a cantilever pier capping beam using a stiffening skeleton according to claim 5, characterized in that: The web member (1.3) is connected to the upper chord (1.1) and the lower chord (1.2) by welding, and the flat bracing (2) is connected to the upper chord node (1.4) or the lower chord node (1.5) by welding.

7. The design method of a cantilever pier capping beam using a stiffening skeleton according to claim 1, characterized in that: The axial force of each member in the main truss panel (1) can be obtained through the structural mechanics calculation diagram. For the compression members, the partial participation of the surrounding concrete (102) in the work is considered, and for the tension members, the effect of the surrounding concrete (102) is ignored.

8. The design method of a cantilever pier capping beam adopting a stiff skeleton according to claim 1, characterized in that: It also includes Key Point 5. The design value of the combined member bearing capacity of the capping beam is calculated according to the following formula: where: N cu,i is the design value of the compressive bearing capacity of the i-th composite member; N tu,i is the design value of the tensile bearing capacity of the i-th composite member; f ci is the design value of the compressive strength of the concrete (102) around the i-th composite member; f si is the design value of the strength of the steel skeleton of the i-th composite member; is the stability coefficient of the i-th composite member under axial compression, and is taken according to the following table: Note: l′ is the calculated length of the member; i′ is the radius of gyration of the cross-section of the composite member; I c is the equivalent cross-section moment of inertia of the surrounding concrete (102) of the composite member, I s is the cross-section moment of inertia of the steel skeleton.

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