Standard type railway bridge concrete block structure and its calculation method

Abstract

The application discloses a standard railway bridge concrete block structure and a calculation method thereof. The structure comprises a block body, a cutting corner part is formed on one side of the block body facing a main beam, a buffer cushion layer is arranged at the cutting corner part, the buffer cushion layer is in abutment with the main beam, and horizontal limiting constraint is formed. The calculation method comprises the following steps: determining a failure mode; determining a horizontal bearing capacity expression of the block structure; determining that the area of a U-shaped main reinforcement satisfies the expression; determining that the area of a ring-shaped main reinforcement satisfies the expression; determining that the bearing angle of the block body satisfies the expression; determining that the size of an adjusting pedestal satisfies the expression; determining that the horizontal hoop reinforcement in the block body satisfies the expression; and completing design calculation. The application establishes relevant design parameters and structure requirements for guaranteeing the stable failure mode of the block structure, and realizes reasonable prediction of the bearing capacity of the new block in the design. The application completely changes the situation that bridge seismic structure measures can only be qualitatively designed and are difficult to guarantee the actual anti-falling beam effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of railway bridge anti-seismic technology, and particularly relates to a standard railway bridge concrete block structure and a calculation method thereof. BACKGROUND

[0002] According to the New Era Traffic Power Railway First-Planning Outline published by the National Railway Group, by 2035, the national railway network will reach about 200,000 kilometers, of which about 70,000 kilometers are high-speed railways, and 20 million population cities will be covered by railways, and 50 million population cities will be reached by high-speed railways. Most of China is located in the middle of the Eurasian seismic belt and the Pacific seismic belt, and a few areas are located on the Eurasian seismic belt. The earthquake region is widely distributed, and it is a country with frequent earthquakes. Railway bridges are an important part of railway operation, especially in high-speed railways, where bridges account for a high proportion. The bridge proportion of Wuhan-Guangzhou high-speed railway is 42%, the bridge proportion of Beijing-Shanghai high-speed railway is 80%, and the bridge proportion of Shanghai-Hangzhou high-speed railway is 92%, which makes China's railways face very serious seismic safety risks.

[0003] Earthquakes are essentially accidental actions, although the probability of occurrence is small, but the destructive power is extremely large. In reality, events that occur far beyond the fortification earthquake level occur from time to time. For example, on May 12, 2008, an 8.0-magnitude earthquake occurred in Wenchuan, which was designed to withstand a 7-degree earthquake, and the actual intensity of the epicenter reached 11 degrees. On May 22, 2021, a 7.4-magnitude earthquake occurred in Maduo, which was designed to withstand a 7-degree earthquake, and the actual intensity of the epicenter was 10 degrees. On January 8, 2022, a 6.9-magnitude earthquake occurred in Menyuan County, Haibei, Qinghai, which was designed to withstand a 7-degree earthquake, and the actual intensity of the epicenter was 9 degrees. The earthquake affected the Lanzhou-Xinjiang high-speed railway from Haomeng to Junmachang section, causing multiple-span typical double-line railway bridge damage, resulting in the suspension of the entire Lanzhou-Xinjiang high-speed railway. A large number of bridge structure earthquake damage investigations show that the use of appropriate seismic structural measures, such as anti-falling beam limiting devices and connections, and necessary support width, has a very significant effect on reducing severe seismic damage such as falling beams, and helps to ensure necessary post-disaster emergency access and reduce post-earthquake repair needs.

[0004] In the existing bridge anti-seismic specification in China, although the relevant requirements of anti-seismic structural measures are generally mentioned, there is no specific structural size and calculation method, which leads to a large randomness in the design of anti-seismic structural measures, and is greatly affected by the designer's understanding level and experience. At present, integral concrete blocks are more commonly used in highway bridges, but they are rarely used in railway bridges, and there are also lack of relevant provisions in the existing specification. In fact, concrete block has the advantages of simple structure, low cost, and good durability, and has significant advantages for the design of anti-falling beam of bridges in medium and low intensity earthquake regions. At the same time, in the strong earthquakes in Wenchuan, Yushu, Maduo and other places, concrete blocks also showed certain anti-falling beam effect. Of course, like other anti-falling beam measures, concrete blocks also have problems such as unclear failure mechanism and failure mode, lack of quantitative calculation of bearing capacity calculation method, etc.

[0005] Based on the above reasons, the application proposes a standard type railway bridge concrete block structure with high bearing capacity and stable failure mode, and proposes a bearing capacity calculation method for the type of anti-falling beam block, thereby realizing the quantitative design of the railway bridge anti-falling beam measure. SUMMARY

[0006] The application is proposed to solve the problems existing in the prior art, and the purpose is to provide a standard type railway bridge concrete block structure and a calculation method thereof.

[0007] The technical scheme of the application is: a standard type railway bridge concrete block structure, comprising a block main body, the side of the block main body facing the main beam forms a chamfered corner portion, a buffer pad layer is arranged at the chamfered corner portion, the buffer pad layer abuts against the main beam to form horizontal limiting constraint, and the block main body is an integrally poured concrete block.

[0008] Further, the block main body is a high-bearing and stable failure block.

[0009] Further, the block main body is arranged on an adjusting pedestal, and the adjusting pedestal is arranged on a bridge pier.

[0010] Further, the block main body, the adjusting pedestal and the bridge pier are integrally poured.

[0011] Further, the chamfered corner portion of the block main body is adapted to the inclination angle of the web plate of the main beam.

[0012] Further, the internal steel structure of the block main body comprises a U-shaped main reinforcement, the U-shaped mouth of the U-shaped main reinforcement faces downward, and the U-shaped main reinforcement is a penetrating steel bar, and the U-shaped main reinforcement is arranged in the adjusting pedestal and the bridge pier.

[0013] Further, the internal steel structure of the block main body comprises a horizontal stirrup, the horizontal stirrup is arranged in multiple layers horizontally in the block main body, and the horizontal stirrup guarantees the shear strength of the block main body.

[0014] Further, the internal steel structure of the block main body comprises a ring-shaped main reinforcement, the ring-shaped main reinforcement is arranged at one end close to the adjusting pedestal, and the arrangement of the ring-shaped main reinforcement forms a designed failure surface to form a stable failure block.

[0015] A calculation method of a standard type railway bridge concrete block structure, comprising the following steps:

[0016] A. Determine the failure mode of the railway bridge concrete block structure;

[0017] B. Obtain the horizontal bearing capacity expression of the block structure under the failure mode;

[0018] C. Based on the horizontal bearing capacity expression, the area of the U-shaped main reinforcement is determined to satisfy the expression;

[0019] D. Based on the area of the U-shaped main reinforcement satisfying the expression, the area of the ring-shaped main reinforcement is determined to satisfy the expression;

[0020] E. The bearing angle of the block body is determined to satisfy the expression;

[0021] F. The size of the adjusting pedestal is determined to satisfy the expression;

[0022] G. The horizontal hoop reinforcement in the block body is determined to satisfy the expression;

[0023] H. The design calculation of the concrete block structure is completed.

[0024] Further, the independent pedestal reinforcement is arranged in the adjusting pedestal, which ensures that the damage range of the block body does not invade the pier, and facilitates post-earthquake repair work.

[0025] The beneficial effects of the present application are as follows:

[0026] The present application is based on the preset damage mode, and proposes a new type of block bearing capacity calculation method, and establishes related design parameters and construction requirements to ensure the stable damage mode, thereby realizing the reasonable prediction of the bearing capacity of the new type of block in the design.

[0027] The quantitative design of the concrete block bearing capacity will completely change the situation that the bridge seismic structure measures can only be designed qualitatively and it is difficult to guarantee its actual anti-falling beam effect, thereby promoting the progress of the bridge seismic design theory. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is the front view of the railway bridge concrete block structure in the present application;

[0029] Figure 2 is the three-view of the railway bridge concrete block structure in the present application;

[0030] Figure 3 is the reinforcement schematic diagram of the railway bridge concrete block structure in the present application;

[0031] Figure 4 is the installation front view of the present application;

[0032] Figure 5 is the detailed size and reinforcement diagram of the present application;

[0033] Among them:

[0034] 1 block body 2 adjusting pedestal

[0035] 3 pier 4 damage surface

[0036] 5 U-shaped main reinforcement bars 6 ring-shaped main reinforcement bars

[0037] 7. Horizontal stirrups; 8. Support reinforcement.

[0038] 9 Main beam 10 Buffer pad Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings and embodiments:

[0040] like Figures 1 to 5 As shown, a standard railway bridge concrete stop block structure includes a stop block body 1. The stop block body 1 has a chamfered part on one side facing the main beam 9. A buffer pad 10 is provided at the chamfered part. The buffer pad 10 abuts against the main beam 9 to form a horizontal limiting constraint. The stop block body 1 is an integrally cast concrete stop block.

[0041] The main body 1 of the block is a high-load-bearing and stable failure-proof block.

[0042] The main body 1 of the block is mounted on the adjustment platform 2, and the adjustment platform 2 is mounted on the bridge pier 3.

[0043] The main body of the block 1, the adjusting platform 2, and the pier 3 are cast into a whole.

[0044] The chamfered portion of the block body 1 is adapted to the inclination angle of the web of the main beam.

[0045] The internal steel reinforcement structure of the block body 1 includes U-shaped main bars 5, with the U-shaped opening of the U-shaped main bars 5 facing downwards. The U-shaped main bars 5 are through bars and are arranged in the adjustment platform 2 and the pier 3.

[0046] The internal steel reinforcement structure of the block body 1 includes horizontal stirrups 7, which are arranged in multiple horizontal layers in the block body 1 to ensure the shear strength of the block body 1.

[0047] The internal steel reinforcement structure of the block body 1 includes a ring-shaped main reinforcement 6. The ring-shaped main reinforcement 6 is arranged at one end near the adjustment platform 2. The arrangement of the ring-shaped main reinforcement 6 forms the designed failure surface 4, thus forming a stable failure block.

[0048] Specifically, such as Figures 1 to 3 As shown, the cross-section of the block body 1 is a chamfered rectangle. The block body 1 is designed with an appropriate width. At the same time, the height of the adjustment platform 2 is changed to ensure that the block body 1 meets the shear-compression failure state, thereby obtaining a larger bearing capacity.

[0049] Specifically, such as Figure 3As shown, the internal reinforcement structure of the block body 1 includes U-shaped main reinforcement 5, horizontal stirrup 7, and ring-shaped main reinforcement 6.

[0050] More specifically, the U-shaped main reinforcement 5 is used to ensure that the pull rod has sufficient strength, and the U-shaped main reinforcement 5 is formed in a chamfer shape at the position corresponding to the chamfered part, so as to adapt to the chamfered part.

[0051] More specifically, the ring-shaped main reinforcement 6 is used to strengthen the block body 1, and an artificial damage surface 4 is formed at the bottom of the block body 1 through the ring-shaped main reinforcement 6, so as to ensure a stable damage mode.

[0052] A method for calculating the structure of a standard railway bridge concrete block, comprising the following steps:

[0053] A. Determine the damage mode of the structure of the railway bridge concrete block;

[0054] B. Obtain the horizontal bearing capacity expression of the block structure under the damage mode;

[0055] C. Based on the horizontal bearing capacity expression, determine that the area of the U-shaped main reinforcement 5 satisfies the expression;

[0056] D. Based on the area of the U-shaped main reinforcement 5 satisfying the expression, determine that the area of the ring-shaped main reinforcement 6 satisfies the expression;

[0057] E. Determine that the bearing angle of the block body 1 satisfies the expression;

[0058] F. Determine that the size of the adjusting pedestal 2 satisfies the expression;

[0059] G. Determine that the horizontal stirrup in the block body 1 satisfies the expression;

[0060] H. Complete the design calculation of the concrete block structure.

[0061] The adjusting pedestal 2 is provided with independent pedestal reinforcement 8, which ensures that the damage range of the block body 1 does not invade the pier 3, and facilitates post-earthquake repair work.

[0062] Specifically, as shown in Figure 1 、 Figure 2 、 Figure 4 Step B obtains the horizontal bearing capacity expression of the block structure under the damage mode, which is as follows:

[0063] According to the damage mode of step A, the horizontal bearing capacity calculation formula is obtained, which is expressed as follows:

[0064]

[0065] Wherein, V is the horizontal bearing capacity of the new block (kN);

[0066] fck f c is the standard value of axial compressive strength of concrete block (MPa) ;

[0067] B is the length of the block (mm) ;

[0068] h0 is the effective height of the bottom section of the block, that is, the distance from the compression force point of the U-shaped main reinforcement 5 to the edge of the compression zone (mm).

[0069] Specifically, step C determines that the area of the U-shaped main reinforcement 5 satisfies the expression based on the horizontal bearing capacity expression, specifically as follows:

[0070] To ensure that the block body 1 has the expected failure mode and achieves the expected bearing capacity, the area of the U-shaped main reinforcement 5 satisfies the expression as follows:

[0071]

[0072] Wherein, A s1 is the area of the U-shaped main reinforcement (mm 2 ) ;

[0073] f ck c is the standard value of axial compressive strength of concrete block (MPa) ;

[0074] B is the length of the block (mm) ;

[0075] H is the effective height of the loading point, that is, the vertical distance from the top surface of the adjusting pedestal to the loading point (mm) ;

[0076] α is the bearing angle of the concrete block;

[0077] f y c is the standard value of axial compressive strength of concrete block (MPa) ;

[0078] Specifically, step D determines that the area of the ring-shaped main reinforcement 6 satisfies the expression based on the area of the U-shaped main reinforcement 5 satisfying the expression, specifically as follows:

[0079] On the basis of step C determining that the area of the U-shaped main reinforcement 5 satisfies the expression, the area of the ring-shaped main reinforcement 6 satisfies the expression as follows:

[0080] A s2 ≥ 0.2A s1 (3)

[0081] Wherein, A s2 is the area of the ring-shaped main reinforcement (mm 2 ), and A s1 is the area of the U-shaped main reinforcement (mm 2 ).

[0082] Specifically, step E determines that the bearing angle of the block body 1 satisfies the expression, specifically as follows:

[0083] On the basis of determining that the area of the U-shaped main reinforcement 5 satisfies the expression in step C, the area of the concrete block bearing angle satisfies the expression as follows:

[0084] α≤50° (4)

[0085] Specifically, step F determines that the size of the adjusting pedestal 2 satisfies the expression, which is specifically as follows:

[0086] The size of the adjusting pedestal 2 satisfies the expression as follows:

[0087] H2≥35mm, b1≥max(H2, 50mm) (5)

[0088] Wherein, H2 is the height of the adjusting pedestal (mm), and b1 is the width of the adjusting pedestal (mm).

[0089] Specifically, step G determines that the horizontal stirrup in the block body 1 satisfies the expression, which is specifically as follows:

[0090] The horizontal stirrup 7 in the block body 1 satisfies the expression as follows:

[0091]

[0092] Wherein, ρ sv is the volume stirrup ratio of the stirrup;

[0093] n is the number of stirrup limbs;

[0094] A sv is the area of the single-limb stirrup (mm 2 );

[0095] s is the stirrup spacing (mm);

[0096] B is the length of the concrete block (mm).

[0097] Specifically, by designing appropriate block body 1 width and adjusting pedestal 2 height, the block body 1 can satisfy the shear compression failure state, so that a larger bearing capacity can be obtained to meet the needs of the block to prevent the beam from falling.

[0098] Specifically, the block body 1 is reinforced by the ring-shaped main reinforcement 6, and the ring-shaped main reinforcement 6 and the adjusting pedestal 2 form an artificial weakened surface 4 at the bottom of the block body 1. The weakened surface 4 forms a stable failure mode, thereby laying a foundation for quantitatively predicting the bearing capacity of the block body 1.

[0099] Specifically, the adjusting pedestal 2 has a suitable structure and independent pedestal reinforcement 8, which ensures that the damage range at the bottom of the block body 1 does not invade into the pier 3, and facilitates the repair work of the structure after the earthquake.

[0100] Example one

[0101] As Figure 4 shown, a certain high-speed railway 32m span double-line simply supported box girder, the main beam weight is about 700 tons, ballast and track and other two-stage constant load single span total weight is about 512 tons, the support cushion stone height is 250mm, the support height is 200mm. The bridge site seismic fortification intensity is 7 degrees, the design seismic peak acceleration is 0.1g, the site characteristic period is divided into two zones, the site category is III, and the seismic response spectrum characteristic period is 0.55s.

[0102] Considering that the design earthquake is 0.1g, the design bearing capacity of the block body 1 of the unilateral anti-falling beam is preliminarily determined as 800kN. The concrete of the block body 1 is C40, and according to the structural size of the pier top, the width of the block is preliminarily determined as 400mm, and the length is 800mm, and the detailed size is as shown in Figure 5 .

[0103] According to formula (1), the bearing capacity of the block body 1 is:

[0104]

[0105] According to formula (2), the area of the U-shaped main reinforcement 5 is:

[0106]

[0107] 8 pieces of HRB400 steel bars with a diameter of 25mm are used, and the total area is 3925mm 2 , which meets the requirements.

[0108] According to formula (3), the ring-shaped main reinforcement 6 uses 8 pieces of HRB400 steel bars with a diameter of 12mm, and the total area is 904mm 2 , which meets the requirements.

[0109] According to Figure 5 , the bearing angle of the block is:

[0110] α=47°, which meets the requirements of formula (4).

[0111] According to Figure 5 , H2=100mm, b1=120mm, which meets the requirements of formula (5).

[0112] The horizontal stirrup 7 uses composite stirrups with a diameter of 12mm, and the number of limbs is 4, and the spacing is 150mm:

[0113] which meets the requirements of formula (6).

[0114] As a variant of the embodiment of the application, the shape and size of the block body 1 can be adjusted according to the size and action height of the main beam.

[0115] As a transformation of the embodiment of the application, the block reinforcement scheme, the shear span ratio, the distance between the block and the edge of the bridge pier, the shape and size of the variable cross-section step and other parameters can be adjusted according to the bearing capacity requirement.

[0116] As a transformation of the embodiment of the application, the block body 1 can be used for the abutment cap and the pier top, and is used for restraining the web plate, the bottom plate, the transverse partition plate and other auxiliary components of the main girder.

[0117] The application proposes a bearing capacity calculation method of the new block based on a preset failure mode, establishes related design parameters and construction requirements for guaranteeing the stable failure mode, and further realizes the reasonable prediction of the bearing capacity of the new block in the design.

[0118] The quantitative design of the bearing capacity of the concrete block will completely change the situation that the bridge seismic construction measures can only be designed qualitatively and it is difficult to guarantee the actual anti-falling beam effect, and further promote the progress of the bridge seismic design theory.

Claims

1. A standard railway bridge concrete retaining block structure, characterized in that: Includes a block body (1), the block body (1) has a chamfered part on the side facing the main beam (9), a buffer pad (10) is provided at the chamfered part, the buffer pad (10) abuts against the main beam (9) to form a horizontal limiting constraint, the block body (1) is an integrally cast concrete block; The main body of the stop block (1) has a cross-section of a chamfered rectangle; The internal steel reinforcement structure of the block body (1) includes U-shaped main bars (5), horizontal stirrups (7), and ring main bars (6); The annular main rib (6) is used to strengthen the block body (1), and the annular main rib (6) forms an artificial damage surface (4) at the bottom of the block body (1) to ensure a stable damage mode; The diagonal line connecting the buffer layer (10) and the failure surface (4) forms a concrete block bearing angle; The U-shaped main bar (5) has its U-shaped opening facing downwards. The U-shaped main bar (5) is a through bar. The U-shaped main bar (5) is arranged in the adjustment platform (2) and the pier (3). The annular main reinforcement (6) is arranged at one end near the adjustment platform (2), and the arrangement of the annular main reinforcement (6) forms the designed failure surface (4), forming a stable failure block.

2. The standard railway bridge concrete stop structure according to claim 1, characterized in that: The main body of the block (1) is a high-load-bearing and stable failure block.

3. The standard railway bridge concrete retaining block structure according to claim 2, characterized in that: The main body (1) of the block is set on the adjustment platform (2), and the adjustment platform (2) is set on the bridge pier (3).

4. The standard railway bridge concrete stop structure according to claim 3, characterized in that: The main body of the block (1), the adjustment platform (2), and the pier (3) are cast into a whole.

5. The standard railway bridge concrete stop structure according to claim 1, characterized in that: The chamfered portion of the block body (1) is adapted to the inclination angle of the web of the main beam.

6. The standard railway bridge concrete stop structure according to claim 2, characterized in that: The internal steel reinforcement structure of the block body (1) includes horizontal stirrups (7), which are arranged in multiple horizontal layers on the block body (1) to ensure the shear strength of the block body (1).

7. A calculation method for the structure of concrete retaining blocks in a standard railway bridge, characterized in that: Includes the following steps: A. Determine the failure mode of the concrete retaining block structure of the railway bridge; B. Determine the expression of the horizontal bearing capacity of the retaining block structure under the obtained failure mode; C. Based on the expression of horizontal bearing capacity, determine the area of ​​the U-shaped main reinforcement (5) to satisfy the expression; D. Based on the area of ​​the U-shaped main reinforcement (5), determine the area of ​​the annular main reinforcement (6) to satisfy the expression; E. Determine that the bearing angle of the main body of the stop (1) satisfies the expression; F. Determine the dimensions of the adjusting base (2) to meet the requirements of the expression; G. Determine the expression of the horizontal stirrups in the main body of the stop block (1); H. Complete the design calculations for the concrete retaining block structure; Based on the failure mode in step A, the formula for calculating the horizontal bearing capacity is obtained, and it is expressed as follows: （1） in, The horizontal bearing capacity of the stop block is (kN). The standard value of the axial compressive strength of the concrete block (MPa); The length of the stop block (mm); The effective height of the bottom section of the block is the distance (mm) from the point of compressive resultant force of the U-shaped main reinforcement (5) to the edge of the compression zone. Step C, based on the expression of horizontal bearing capacity, determines the area of ​​the U-shaped main reinforcement (5) to satisfy the expression, as follows: To ensure that the main body of the retaining block (1) experiences the expected failure mode and achieves the expected bearing capacity, the area of ​​the U-shaped main reinforcement (5) satisfies the following expression: （2） in, Area of ​​U-shaped main reinforcement (mm²) 2 ); The standard value of the axial compressive strength of the concrete block (MPa); The length of the stop block (mm); The effective height of the loading point is the vertical distance (mm) from the top surface of the adjustment platform to the loading point. For the bearing angle of the concrete stop block; The design value of the resistance strength of the U-shaped main reinforcement (MPa); Step D, based on the area of ​​the U-shaped main reinforcement (5), determines the area of ​​the annular main reinforcement (6) to satisfy the expression, as follows: Based on the determination in step C that the area of ​​the U-shaped main reinforcement (5) satisfies the expression, the area of ​​the annular main reinforcement (6) satisfies the expression as follows: （3） in, Area of ​​the ring-shaped main reinforcement (mm²) 2 ), Area of ​​U-shaped main reinforcement (mm²) 2 ); Step E determines that the bearing angle of the block body (1) satisfies the expression, as follows: Based on the determination in step C that the area of ​​the U-shaped main reinforcement (5) satisfies the expression, the area of ​​the bearing angle of the concrete stop block satisfies the expression as follows: （4）。 8. The calculation method for the construction of a standard railway bridge concrete retaining block according to claim 7, characterized in that: The adjustment platform (2) is provided with independent platform reinforcement (8). The platform reinforcement (8) ensures that the damage range of the block body (1) does not intrude into the pier (3), which facilitates the post-earthquake repair work.

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