Standard railway bridge elastoplastic stopper structure and probabilistic performance evaluation method therefor

Abstract

Disclosed in the present invention are a standard railway bridge elastoplastic stopper structure and a probabilistic performance evaluation method therefor. The stopper structure comprises a base plate, wherein a first stopper unit and a second stopper unit are arranged on the lower end of the base plate; the first stopper unit and the second stopper unit are arranged in bilateral symmetry; the first stopper unit and the second stopper unit each comprise a trapezoidal component; and each trapezoidal component is of a trapezoidal shape in the transverse direction of a box-girder bottom plate. The method comprises the following steps: determining an appropriate seismic motion input; establishing a structural nonlinear analysis model; on the basis of the seismic motion input and the structural nonlinear analysis model, determining a probabilistic expression of unseating-prevention performance; and evaluating the actual performance of the elastoplastic stopper structure. The present invention has a stable plastic mechanism and good deformation and energy dissipation capabilities, and can significantly improve the unseating-prevention performance of a stopper. The present invention provides a probabilistic evaluation method for unseating-prevention performance, thus realizing reasonable quantitative evaluation of the unseating-prevention performance of an anti-seismic stopper of a railway bridge.

Description

Elastoplastic block structure of standard railway bridge and probabilistic evaluation method of its effectiveness Technical Field

[0001] The present invention belongs to the technical field of railway bridge earthquake resistance, and in particular relates to a standard railway bridge elastic-plastic block structure and a method for evaluating its effectiveness probabilistically. Background Art

[0002] Most of my country lies within the Eurasian and Pacific seismic belts, with a few areas located on the Eurasian seismic belt. Seismic activity is widespread, making China a country prone to frequent earthquakes. Railway bridges are crucial to railway operations, particularly on high-speed railways. Bridges account for 42% of the Wuhan-Guangzhou High-Speed ​​Railway, 80% of the Beijing-Shanghai High-Speed ​​Railway, and 92% of the Shanghai-Hangzhou High-Speed ​​Railway. Currently, my country's railway construction focus is gradually shifting to the high-intensity seismic zones in western my country, exposing the country to significant seismic safety risks.

[0003] Earthquakes are essentially accidental events, with a low probability of occurrence but extremely destructive potential. In reality, events where actual seismic activity far exceeds the designated earthquake level occur from time to time. For example, on May 12, 2008, an 8.0 magnitude earthquake struck Wenchuan, with a designated intensity of 7, and an actual intensity of 11 at the epicenter. On May 22, 2021, a 7.4 magnitude earthquake struck Maduo, with a designated intensity of 7, and an actual intensity of 10 at the epicenter. On January 8, 2022, a 6.9 magnitude earthquake struck Menyuan County, Haibei Prefecture, Qinghai, with a designated intensity of 7, and an actual intensity of 9 at the epicenter. As a result of the earthquake, multiple spans of typical double-track railway bridges on the Haomen to Junmachang section of the Lanzhou-Xinjiang High-Speed ​​Railway were damaged, resulting in the suspension of service on the entire Lanzhou-Xinjiang High-Speed ​​Railway. A large number of earthquake damage investigations on bridge structures have shown that the adoption of appropriate seismic structural measures, such as anti-falling beam limiters and connections and necessary support widths, has a very significant effect on reducing serious earthquake damage such as falling beams, helping to ensure the necessary post-disaster emergency traffic capacity and reduce the need for post-earthquake repairs.

[0004] Typical steel blocks on existing railway bridges are constructed by welding short I-shaped or box-section steel columns to the base plate. Under earthquake action, the welds between the base plate and the block body are prone to shear failure. During the Menyuan earthquake, a large number of steel blocks suffered this type of failure. This failure mode is brittle, resulting in minimal deformation and low energy dissipation, making it very limited in its ability to withstand strong earthquakes and reduce the risk of beam collapse.

[0005] In addition, the seismic stops of existing railway bridges all adopt qualitative structural design and lack quantitative evaluation methods, resulting in uneven design of seismic stops of existing railway bridges and difficulty in ensuring the expected anti-falling beam effect.

[0006] Based on the above reasons, this paper proposes a standard elastoplastic stopper for railway bridges. This block exhibits a stable plastic mechanism, excellent deformation and energy dissipation capabilities, and significantly improves its effectiveness in preventing beam drop. Furthermore, a probabilistic assessment method for this effectiveness is proposed, enabling a rational quantitative evaluation of the effectiveness of seismic stoppers for railway bridges. Summary of the Invention

[0007] The present invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a standard railway bridge elastic-plastic block structure and a probabilistic evaluation method for its effectiveness.

[0008] The technical solution of the present invention is: a standard railway bridge elastic-plastic block structure, including a base plate, a first block unit and a second block unit are provided at the lower end of the base plate, the first block unit and the second block unit are arranged symmetrically on the left and right, the first block unit and the second block unit both include trapezoidal components, and the trapezoidal components are trapezoidal in the transverse direction of the box beam base plate.

[0009] Furthermore, the bottom plate is fixed to the lower end of the box beam bottom plate, and the box beam bottom plate is erected on the support pad stone.

[0010] Furthermore, the end of the trapezoidal component facing the side support pedestal stone is the lower bottom end of the trapezoid, and the end of the trapezoidal component away from the side support pedestal stone is the upper bottom end of the trapezoid.

[0011] Furthermore, the trapezoidal assembly includes a plurality of trapezoidal steel plates, each of which includes a trapezoidal section and a widened and strengthened section.

[0012] Furthermore, the trapezoidal steel plate is inverted, the widened reinforcement section is connected to the longer lower bottom side of the trapezoidal section as a whole, and the widened reinforcement section is connected to the lower end of the bottom plate.

[0013] Furthermore, the vertical spacing between the lower bottom side and the upper bottom side of the trapezoidal segment is gradually changed, so that a plurality of trapezoidal steel plates are combined to form a trapezoidal assembly.

[0014] Furthermore, the bottom plate and the box beam bottom plate are fixed by an array-type connecting assembly.

[0015] Furthermore, the support pad stone is arranged on the bridge pier.

[0016] The probabilistic evaluation method for the effectiveness of the elastic-plastic stop structure of a standard railway bridge includes the following steps:

[0017] A. Determine the appropriate ground motion input;

[0018] B. Establish a structural nonlinear analysis model;

[0019] C. Determine the probabilistic expression of the effectiveness of beam fall prevention based on earthquake motion input and structural nonlinear analysis model;

[0020] D. Evaluate the practical effectiveness of elastic-plastic stopper structures.

[0021] Furthermore, step C determines the probability expression of the effectiveness of the anti-falling beam based on the earthquake input and the structural nonlinear analysis model, as follows:

[0022] First, based on the structural nonlinear analysis model, a nonlinear time-history analysis of the structural seismic response is carried out for all selected seismic inputs.

[0023] Then, determine whether beam fall occurs based on the actual earthquake response;

[0024] Finally, the effectiveness probability expression of the anti-fall beam, i.e., the elastic-plastic stopper structure, is obtained.

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

[0026] The elastic-plastic stopper of the present invention realizes approximately equal strength design of a single-layer steel plate through reasonable structure and parameter design, which can fully utilize the plastic properties of the material, thereby making the stopper have greater deformation capacity and energy consumption capacity, and significantly improving its anti-falling beam effect.

[0027] In the present invention, the bottom of the trapezoidal steel plate adopts a widened reinforcement section design and is provided with trapezoidal stiffening ribs, which can ensure that the widened reinforcement section and the bottom weld maintain elastic operation while avoiding local buckling. The bottom plate is anchored to the top of the pier by anchor bolts, and it is ensured that the anchor bolts will not be damaged under the action of the ultimate horizontal bearing capacity of the block, thereby ensuring that the plastic mechanism of the block stably occurs in the trapezoidal area of ​​the stacked steel plates.

[0028] The present invention accurately analyzes the nonlinear behavior of the structure and the anti-falling beam efficacy of the block based on a nonlinear model and analysis process, establishes a probabilistic evaluation method for the anti-falling beam efficacy, and realizes a reasonable quantitative evaluation of the anti-falling beam efficacy of the seismic block of the railway bridge. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a side view of the elastic-plastic block structure of a standard railway bridge according to the present invention;

[0030] FIG2 is a front view of the elastic-plastic block structure of a standard railway bridge according to the present invention;

[0031] FIG3 is an elevation view of the elastic-plastic block structure of a standard railway bridge according to the present invention;

[0032] FIG4 is a schematic diagram of the installation of the elastic-plastic block structure of a standard railway bridge according to the present invention;

[0033] FIG5 is an acceleration response spectrum of an extremely rare earthquake in an embodiment of the present invention;

[0034] FIG6 is a simulation of a reasonable constitutive relationship considering the unidirectional constraint behavior of the elastic-plastic stopper in an embodiment of the present invention;

[0035] 7 is a diagram showing the relative displacement analysis results of the pier-beam according to an embodiment of the present invention (FIG. a is a diagram showing the relative displacement analysis results of the pier-beam with elastic-plastic stoppers, and FIG. b is a diagram showing the relative displacement analysis results of the pier-beam without elastic-plastic stoppers);

[0036] in:

[0037] 1 Trapezoidal steel plate 2 Trapezoidal assembly 3 Widened and reinforced section 4 Weld 5 Base plate 6 Anchor bolts 7 Trapezoidal stiffener 8 Box girder base plate 9 Support pad 10 Bridge pier. Modes for Carrying Out the Invention

[0038] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and embodiments:

[0039] As shown in Figures 1 to 7, the standard railway bridge elastic-plastic block structure includes a base plate 5, and a first block unit and a second block unit are provided at the lower end of the base plate 5. The first block unit and the second block unit are arranged symmetrically on the left and right. The first block unit and the second block unit both include a trapezoidal component 2, and the trapezoidal component 2 is trapezoidal in the transverse direction of the box beam bottom plate 8.

[0040] The bottom plate 5 is fixed to the lower end of the box beam bottom plate 8 , and the box beam bottom plate 8 is erected on the support pad 9 .

[0041] The end of the trapezoidal component 2 facing the side support pedestal stone 9 is the lower bottom end of the trapezoid, and the end of the trapezoidal component 2 away from the side support pedestal stone 9 is the upper bottom end of the trapezoid.

[0042] The trapezoidal assembly 2 includes a plurality of trapezoidal steel plates 1 , each of which includes a trapezoidal segment and a widened and reinforced segment 3 .

[0043] The trapezoidal steel plate 1 is inverted, and the widened and reinforced section 3 is connected to the longer lower bottom side of the trapezoidal section as a whole. The widened and reinforced section 3 is connected to the lower end of the bottom plate 5.

[0044] The vertical spacing between the lower bottom side and the upper bottom side of the trapezoidal segment is gradually changed, so that a plurality of trapezoidal steel plates 1 are combined to form a trapezoidal assembly 2 .

[0045] The bottom plate 5 and the box beam bottom plate 8 are fixed by an array of connecting components.

[0046] The support pad stone 9 is arranged on the bridge pier 10 .

[0047] Specifically, as shown in Figures 1 to 4, five trapezoidal steel plates 1 are used as an example. The five trapezoidal steel plates 1 have different spacings between their upper and lower bases, and the spacings between their upper and lower bases are an arithmetic progression.

[0048] Specifically, five trapezoidal steel plates 1 are fitted together and connected to the bottom plate 5 via the widened reinforcement section 3 .

[0049] Specifically, five trapezoidal steel plates 1 form a first stopper unit, and five trapezoidal steel plates 1 form a second stopper unit. The first stopper unit and the second stopper unit are located between two support pads 9, and the first stopper unit and the second stopper unit are bilaterally symmetrical.

[0050] Specifically, the trapezoidal steel plates 1 are stacked to form a reasonable trapezoidal assembly 2. The multi-layer stacking scheme achieves equal strength design of the single-layer steel plates, so that the plastic mechanism develops more evenly throughout the entire steel plate.

[0051] Specifically, the bottom end of each trapezoidal steel plate 1 is fully welded to the bottom plate 5 through the widened reinforcement section 3 .

[0052] More specifically, trapezoidal stiffening ribs 7 are provided on the side walls of the widened and reinforced section 3 to ensure that the widened and reinforced section 3 and the weld 4 at the bottom maintain elastic operation and avoid entering plasticity and local buckling.

[0053] More specifically, the arc transition between the trapezoidal steel plate 1 and the widened and strengthened section 3 avoids stress concentration leading to premature failure.

[0054] Specifically, the height of the multi-layer trapezoidal steel plates 1 gradually decreases from front to back, which on the one hand ensures the equal strength design parameters of the trapezoidal steel plates 1 and on the other hand increases the horizontal resistance of the entire block.

[0055] Specifically, the friction effect between the multiple layers of stacked trapezoidal steel plates 1 also helps to increase the energy consumption of the stopper.

[0056] Specifically, the bottom plate 5 is anchored to the box beam bottom plate 8 through the anchor bolts 6 in the connection assembly, while ensuring that the anchor bolts 6 will not be damaged under the action of the block's ultimate horizontal bearing capacity, thereby ensuring that the plastic mechanism of the block occurs stably in the trapezoidal assembly 2 of the stacked steel plates.

[0057] Specifically, the inner sides of the stacked trapezoidal steel plates 1 abut against the support pads 9, thereby forming a restraining effect to prevent the beam from falling under the action of an earthquake.

[0058] Specifically, the vertical height of the trapezoidal stiffening rib 7 is consistent with that of the widened reinforcement section 3 .

[0059] The probabilistic evaluation method for the effectiveness of the elastic-plastic stop structure of a standard railway bridge includes the following steps:

[0060] A. Determine the appropriate ground motion input;

[0061] B. Establish a structural nonlinear analysis model;

[0062] C. Determine the probabilistic expression of the effectiveness of beam fall prevention based on earthquake motion input and structural nonlinear analysis model;

[0063] D. Evaluate the practical effectiveness of elastic-plastic stopper structures.

[0064] Step C determines the probability expression of the effectiveness of the anti-falling beam based on the earthquake input and the structural nonlinear analysis model, as follows:

[0065] First, based on the structural nonlinear analysis model, a nonlinear time-history analysis of the structural seismic response is carried out for all selected seismic inputs.

[0066] Then, determine whether beam fall occurs based on the actual earthquake response;

[0067] Finally, the effectiveness probability expression of the anti-fall beam, i.e., the elastic-plastic stopper structure, is obtained.

[0068] Specifically, step A determines the appropriate earthquake motion input as follows:

[0069] Select appropriate strong earthquake records or coordinated artificial seismic waves as the seismic input for earthquake-resistant structural measures;

[0070] More specifically, the probabilistic quantitative evaluation of the effectiveness of anti-falling beam measures requires a sufficient number of seismic waves to meet the needs of probabilistic evaluation. Therefore, a group of seismic waves is needed. It is recommended that no less than 30 seismic waves be selected in a group of seismic waves.

[0071] As a structural seismic protection measure, anti-fall beams are not primarily designed to address the design earthquake level. Current railway bridges are designed to withstand multiple, design, and rare earthquakes. The effectiveness of anti-fall beam measures primarily focuses on earthquakes exceeding the design earthquake level.

[0072] According to the China Earthquake Motion Parameter Zoning Map GB18306-2015, the peak acceleration of an extremely rare earthquake can be taken as 2.7-3.2 times the basic acceleration. Therefore, the seismic action of the anti-fall beam measures is determined according to the extremely rare earthquake protection, and the peak acceleration is taken as 3.2 times the basic acceleration on the safe side.

[0073] More specifically, the characteristic period is increased by 0.05s on the basis of the rare earthquake, that is, compared with the design earthquake action,

[0074] The characteristic period of the response spectrum is increased by 0.1s. According to this target spectrum, appropriate strong earthquake records or coordinated artificial seismic waves are selected as the seismic input for seismic structural measures.

[0075] Specifically, step B establishes a structural nonlinear analysis model as follows:

[0076] Under extremely rare strong earthquakes, both beam-fall prevention measures and certain key structural components, such as supports and dampers, exhibit strong nonlinear behavior. Therefore, accurately characterizing these nonlinear behaviors is crucial for accurately assessing the seismic response of structures under strong earthquakes and determining the effectiveness of beam-fall prevention measures.

[0077] The anti-falling beam measure in the present invention is different from the general mild steel damper, which generally has only one-way constraint. In the simulation, a typical bilinear damping unit and a gap unit (compression only, no tension) can be used in series for simulation.

[0078] Specifically, step C determines the probability expression of the effectiveness of the anti-falling beam based on the earthquake input and the structural nonlinear analysis model, as follows:

[0079] First, based on the structural nonlinear analysis model in step B, a nonlinear time-history analysis of the structural seismic response is performed for all selected seismic waves;

[0080] Then, it is determined whether beam fall occurs based on the actual seismic response of the structure;

[0081] Finally, the efficacy probability is expressed as follows:

[0082] (1)

[0083] Where Di is the relative displacement of the pier and beam under the action of the i-th earthquake wave;

[0084] Dmax is the maximum allowable relative displacement of the pier and beam;

[0085] N is the number of seismic wave conditions where the relative displacement of the pier and beam is less than the maximum allowable relative displacement of the pier and beam;

[0086] Ntotal is the total number of seismic wave calculation conditions.

[0087] Specifically, step D evaluates the actual effectiveness of the elastic-plastic stopper structure as follows:

[0088] By comparing the difference in the probability of anti-falling beam effectiveness when using elastic-plastic anti-falling beam stoppers and when not using anti-falling beam stoppers, the actual effectiveness of the elastic-plastic anti-falling beam stoppers can be further evaluated.

[0089] Specifically, the trapezoidal steel plate 1 adopts a trapezoidal shape design, and through a multi-layer stacking scheme, an approximately equal strength design of a single-layer steel plate is achieved, so that the plastic mechanism develops more evenly within the entire trapezoidal area of ​​the steel plate, which can maximize the plastic properties of the steel, improve the utilization rate of the material, and thereby enhance the deformation capacity and energy consumption capacity of the block, and ultimately improve its anti-falling beam effect.

[0090] Specifically, the widened reinforcement section 3 is adopted at the bottom of the trapezoidal steel plate 1, which can ensure that the widened reinforcement section 3 and the weld 4 maintain elastic operation, thereby avoiding the brittle failure mode caused by weld damage, and ensuring that the entire block first yields within the trapezoidal component 2 to form a stable plastic mechanism.

[0091] Specifically, the bottom plate 5 is anchored to the box beam bottom plate 8 by anchor bolts 6 , and ensures that the anchor bolts 6 will not be damaged under the action of the limit horizontal bearing capacity of the block, thereby ensuring that the plastic mechanism of the block occurs stably in the trapezoidal component 2 .

[0092] Specifically, the height of the multi-layer trapezoidal steel plates 1 is gradually reduced, which on the one hand ensures the equal strength design parameters of the steel plates, and on the other hand can increase the horizontal resistance of the entire trapezoidal component 2.

[0093] Specifically, the friction effect between the multiple layers of trapezoidal steel plates 1 also helps to increase the energy consumption of the stopper.

[0094] Specifically, a reasonable seismic input was determined based on extremely rare earthquakes, and a reasonable nonlinear analysis model was established based on the nonlinear behavior of the blocks. Then, a probabilistic evaluation method for the effectiveness of anti-falling beam blocks was established, realizing a reasonable quantitative evaluation of the effectiveness of anti-falling beam blocks on railway bridges.

[0095] Example 1

[0096] Figure 5 shows the acceleration response spectra for design, rare, and extremely rare earthquakes in a 32-meter high-speed railway bridge in an 8-magnitude earthquake zone. The adjustment factor for the peak acceleration of an extremely rare earthquake compared to the peak acceleration of the design earthquake is 3.2. The site category is III, and the characteristic period is divided into three zones. The corresponding characteristic period of the response spectrum is 0.65s, while the characteristic period for an extremely rare earthquake is 0.75s. Using the acceleration response spectrum of the extremely rare earthquake as the target spectrum, 10 strong earthquake records were selected to generate 20 artificial seismic waves, for a total of 30 seismic waves. The response spectra corresponding to the 30 ground motions and their average response spectrum are shown in Figure 5. It can be seen that the response spectra corresponding to each wave are well coordinated with the target response spectrum, and the average spectrum is highly consistent with the target spectrum.

[0097] As shown in Figure 6, a reasonable constitutive relationship simulation considering the unidirectional constraint behavior of the elastic-plastic stopper is established. This reasonable constitutive relationship is applied to the full-bridge spatial dynamic finite element model to form a reasonable mechanical analysis model that can reasonably simulate the nonlinear behavior of the elastic-plastic stopper.

[0098] It should be noted that the remaining structural parts except the elastic-plastic blocks should be able to reflect their nonlinear behavior under strong earthquakes. For example, a fiber beam model is used to simulate the plastic behavior of reinforced concrete bridge piers, a bilinear model combined with an ultimate strain model is used to simulate the nonlinear behavior of the supports within their displacement capacity, and a friction hysteresis model is used to simulate the sliding behavior of the main beam at the pier top after dislocation.

[0099] As shown in Figures 7a and 7b, Figures 7a and 7b respectively show the analysis results of the relative displacement of piers and beams under the action of 30 extremely rare earthquake waves for two structural systems with and without elastic-plastic stops.

[0100] It can be seen that the introduction of elastic-plastic stops can generally reduce the relative displacement of piers and beams under rare earthquakes. Considering an effective lap length of 1.0 m, it can be seen that without the use of elastic-plastic stops, there are eight seismic wave conditions where the relative displacement of the piers and beams exceeds the effective lap length. With the use of elastic-plastic stops, there are three seismic wave conditions where the relative displacement of the piers and beams exceeds the effective lap length. The probability of beam fall risk is reduced from 27% to approximately 10%, effectively reducing the risk of beam fall.

[0101] As a variation of the embodiment of the present invention, the size and quantity of the trapezoidal steel plates 1 can be adjusted according to the bearing capacity and deformation requirements of the anti-fall beam block.

[0102] As a variation of the embodiment of the present invention, the trapezoidal steel plate 1 and the bottom plate 5 may be anchored together by other consolidation and anchoring methods such as integral casting.

[0103] As a variation of the embodiment of the present invention, the number of anchor bolts 6 between the stopper and the main beam can be adjusted according to the bearing capacity of the stopper, or other anchoring methods such as welding can be used.

[0104] As a variation of the embodiment of the present invention, the block can be anchored to the pier top, and the baffle can be used to constrain the main beam web, bottom plate, diaphragm and other auxiliary components.

[0105] The elastic-plastic stopper of the present invention realizes approximately equal strength design of a single-layer steel plate through reasonable structure and parameter design, which can fully utilize the plastic properties of the material, thereby making the stopper have greater deformation capacity and energy consumption capacity, and significantly improving its anti-falling beam effect.

[0106] In the present invention, the bottom of the trapezoidal steel plate adopts a widened reinforcement section design and is provided with trapezoidal stiffening ribs, which can ensure that the widened reinforcement section and the bottom weld maintain elastic operation while avoiding local buckling. The bottom plate is anchored to the top of the pier by anchor bolts, and it is ensured that the anchor bolts will not be damaged under the action of the ultimate horizontal bearing capacity of the block, thereby ensuring that the plastic mechanism of the block stably occurs in the trapezoidal area of ​​the stacked steel plates.

[0107] The present invention accurately analyzes the nonlinear behavior of the structure and the anti-falling beam efficacy of the block based on a nonlinear model and analysis process, establishes a probabilistic evaluation method for the anti-falling beam efficacy, and realizes a reasonable quantitative evaluation of the anti-falling beam efficacy of the seismic block of the railway bridge.

Claims

1. A standard type railway bridge elastic-plastic block structure, comprising a bottom plate (5), characterized in that: A first stop block unit and a second stop block unit are provided at the lower end of the bottom plate (5), the first stop block unit and the second stop block unit being arranged symmetrically on the left and right, and the first stop block unit and the second stop block unit both comprising a trapezoidal component (2), the trapezoidal component (2) being in a trapezoidal shape in the transverse direction of the box beam bottom plate (8).

2. The standard railway bridge elastic-plastic block structure according to claim 1 is characterized in that: The bottom plate (5) is fixed to the lower end of the box beam bottom plate (8), and the box beam bottom plate (8) is mounted on the support pad stone (9).

3. The standard railway bridge elastic-plastic block structure according to claim 2 is characterized in that: The end of the trapezoidal component (2) facing the side support pedestal stone (9) is the lower end of the trapezoid, and the end of the trapezoidal component (2) away from the side support pedestal stone (9) is the upper end of the trapezoid.

4. The standard railway bridge elastic-plastic block structure according to claim 1 is characterized in that: The trapezoidal assembly (2) comprises a plurality of trapezoidal steel plates (1), each of the trapezoidal steel plates (1) comprising a trapezoidal section and a widened and strengthened section (3).

5. The standard type railway bridge elastic-plastic block structure according to claim 4, characterized in that: The trapezoidal steel plate (1) is inverted, the widened reinforcement section (3) is connected to the longer lower bottom side of the trapezoidal section as a whole, and the widened reinforcement section (3) is connected to the lower end of the bottom plate (5).

6. The standard railway bridge elastic-plastic block structure according to claim 5, characterized in that: The vertical spacing between the lower bottom side and the upper bottom side of the trapezoidal segment is gradually changed, so that a plurality of trapezoidal steel plates (1) are combined to form a trapezoidal assembly (2).

7. The standard railway bridge elastic-plastic block structure according to claim 2, characterized in that: The bottom plate (5) and the box beam bottom plate (8) are fixed via an array-type connection assembly.

8. The standard railway bridge elastic-plastic block structure according to claim 2, characterized in that: The support pad stone (9) is arranged on the bridge pier (10).

9. A probabilistic evaluation method for the effectiveness of elastic-plastic stop structures in standard railway bridges, characterized by: The following steps are involved: A. Determine the appropriate ground motion input; B. Establish a structural nonlinear analysis model; C. Determine the probabilistic expression of the effectiveness of beam fall prevention based on earthquake motion input and structural nonlinear analysis model; D. Evaluate the practical effectiveness of elastic-plastic stopper structures.

10. The standard railway bridge elastoplastic block structure and its effectiveness probabilistic evaluation method according to claim 9, Its characteristics are: Step C determines the probability expression of the effectiveness of the anti-falling beam based on the earthquake input and the structural nonlinear analysis model, as follows: First, based on the structural nonlinear analysis model, a nonlinear time-history analysis of the structural seismic response is carried out for all selected seismic inputs. Then, determine whether beam fall occurs based on the actual earthquake response; Finally, the effectiveness probability expression of the anti-fall beam, i.e., the elastic-plastic stopper structure, is obtained.

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