Stress analysis method for erecting bridge with narrow precast beam with slope curve

Abstract

The application relates to the technical field of bridge construction, in particular to a stress analysis method for erecting a construction bridge by using a narrow-width precast beam with a slope curve, which comprises the following steps: a beam-erecting machine beam structure model is established according to structural material parameters, wherein the structural material parameters include highway beam-erecting machine parameters, bridge structure parameters and I-beam prestressed steel strand parameters; various types of checking loads acting on the beam-erecting machine and the precast I-beam are calculated and determined based on the structural model, wherein the checking loads include self-weight, beam-erecting machine load, wind load and steel strand prestressed load; the stress conditions of the bridge are analyzed based on different working conditions; the eligibility of the beam-erecting machine beam process is determined according to the bridge deformation displacement results and the bridge concrete stress results; and the construction optimization strategy is determined according to the direction of the maximum displacement of the bridge deformation. The safety and stability of the beam structure are ensured through simulation modeling and theoretical analysis.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, and in particular to a stress analysis method for bridges constructed with narrow precast beams on sloping curves. Background Technology

[0002] With the rapid development of my country's transportation infrastructure, highways and urban viaducts often inevitably feature small-radius horizontal curves and longitudinal slopes in order to adapt to complex terrain. This results in precast beam bridges exhibiting significant characteristics such as slopes, curves, and narrow spans. In the construction of such bridges, the use of bridge erecting machines for precast beam erection has become the mainstream technology.

[0003] However, the erection process of such complex-shaped bridges presents unprecedented challenges to structural stress analysis. Currently, conventional bridge stress analysis methods are mainly based on ideal assumptions of straight lines and level slopes, and primarily focus on the overall load effects during the completed bridge stage. For the structural behavior during the dynamic construction process, especially the mechanical state under the interaction between the bridge erecting machine and the uncompleted bridge system, the analysis methods are relatively simplified and have significant limitations. The inherent bending-torsion coupling effect of curved beams, combined with the longitudinal component of the load from the longitudinal slope, results in an exceptionally complex transmission path for loads such as the bridge erecting machine's support reaction force and the self-weight of the precast beams, leading to severe eccentric compression of the substructure. Traditional calculation methods struggle to accurately simulate this complex spatial stress pattern, cannot effectively assess the local stress concentration and strength safety of the cap beam, and exhibit significant calculation biases and safety hazards.

[0004] Chinese Patent Application Publication No. CN120579262A discloses a method for measuring the stress of bridge support columns based on structural collaborative stress analysis, belonging to the field of stress measurement technology. This method involves real-time acquisition of stress, strain, and displacement data for each bridge support column; calculation of the local stress index for each support column based on the acquired real-time data; establishment of a structural collaborative stress model based on the overall bridge structural parameters and the connection relationships between the support columns; calculation of the collaborative stress correction index for each support column; comparison of the collaborative stress correction index with the dynamic stress assessment interval; trend analysis combining historical data and environmental factors to determine the existence of structural risks; and issuance of an early warning signal when the threshold is exceeded.

[0005] However, the existing technology has the following problems: For the special construction process of erecting narrow precast beams with sloping curves, which is dynamic, complex and high-risk, the existing technology is significantly insufficient in terms of forward prediction, complex spatial stress simulation, special analysis of key components and dynamic effect assessment. It cannot provide a full-process, high-precision theoretical basis and decision support for construction safety. Summary of the Invention

[0006] To address this issue, the present invention provides a stress analysis method for bridges constructed with narrow precast beams on sloping curves, thereby overcoming the problem in the prior art that the mechanical behavior analysis of complex-shaped bridges during construction is insufficient and cannot achieve high-precision safety assessment.

[0007] To achieve the above objectives, this invention provides a stress analysis method for constructing bridges with narrow precast beams and sloping curves, comprising: A bridge erection machine beam erection structure model is established based on structural material parameters, including highway bridge erection machine parameters, bridge structure parameters, and I-beam prestressed steel strand parameters. Based on the structural model, various verification loads acting on the bridge erecting machine and the precast I-beam are calculated and determined. The verification loads include self-weight, bridge erecting machine load, wind load, and steel strand prestress load. The stress condition of the bridge is analyzed based on different working conditions, including working condition 1, working condition 2, working condition 3 and working condition 4. The qualification of the bridge erection machine's beam erection process is determined based on the bridge deformation displacement results and the bridge concrete stress results. Under the condition that the bridge girder erection process is qualified, the construction optimization strategy is determined according to the direction of the maximum displacement of bridge deformation.

[0008] Furthermore, the working condition 1 is the maximum stress condition of the cap beam under the action of the front support leg, that is, when the bridge erecting machine is erecting the side beam, the pressure transmitted to the cap beam by the front support leg through the transverse track and sleepers is the greatest.

[0009] Furthermore, the working condition 2 is the maximum stress condition of the precast beam end under the action of the middle support leg, that is, when the bridge erecting machine is erecting the side beam, the pressure transmitted by the middle support leg to the precast beam and cap beam through the transverse track and sleepers is the greatest.

[0010] Furthermore, condition 3 represents the most unfavorable stress situation for the middle section of the erected precast beam under the action of the support legs, including the following situations: Condition 3-1: When the bridge erecting machine is in the beam feeding state, the tail support leg is at the first preset distance from the front end of the erected precast beam, and the pressure of the tail support leg transmitting force to the precast beam through the steel beam is at its maximum. Condition 3-2: The bridge erecting machine is in the beam feeding state. The position of the tail leg is the second preset distance from the front end of the erected precast beam. The tail leg transmits the force to the precast beam through the steel beam. The two tail legs exert the maximum force on the bridge deck. Condition 3-3: When the bridge erecting machine is in the span crossing state, the position of the tail leg is three preset distances away from the front end of the precast beam that has been erected. The tail leg transmits the force to the precast beam through the steel beam. The two tail legs exert the maximum force on the bridge deck. In working condition 3-4, the bridge erecting machine is in the span crossing state. The distance between the lateral track of the middle support leg of the bridge erecting machine and the front end of the precast beam has been preset to the fourth distance. The middle support leg transmits the data to the precast beam through the lateral track and sleepers. The two middle support legs have the maximum impact on the bridge deck.

[0011] Furthermore, the working condition 4 is the most unfavorable load condition of the precast beam under the action of the beam transport vehicle, that is, the beam transport trolley moves by means of the steel rails erected on two adjacent precast beams, and the bending moment generated on the precast beam is the greatest when the trolley moves to the mid-span position of the precast beam.

[0012] Furthermore, the bridge erection machine's girder erection process is deemed qualified if and only if all of the following conditions are met: The maximum displacement of the bridge deformation is less than the preset deflection value; The maximum stress value of the prestressed I-beam is less than the first preset compressive strength design value; The maximum compressive stress value of the cap beam is less than the second preset tensile strength design value.

[0013] Furthermore, a construction optimization strategy is determined based on the direction of the maximum displacement of the bridge deformation, wherein... If the direction of the maximum deformation displacement is transverse, temporary tie beams are added at the ends and middle of the concrete I-beam segments; If the direction of the maximum deformation displacement is longitudinal, then steel wire ropes are used to anchor the cap beam to the temporary tie beam at the bottom of the I-beam.

[0014] Furthermore, the number of temporary tie beams to be added in the middle of the I-beam segment is determined based on the transverse composite load stability coefficient. If the stability coefficient of the transverse composite load is less than the preset stability coefficient, then the number of temporary tie beams to be increased is determined to be the first preset number. If the stability coefficient of the transverse composite load is greater than or equal to the preset stability coefficient, then the number of temporary tie beams to be increased is determined to be the second preset number.

[0015] Furthermore, the stability coefficient of the lateral composite load is determined jointly by the lateral wind load and the lateral braking load.

[0016] Compared with the prior art, the beneficial effects of the present invention are that it addresses the problem of insufficient analysis of the mechanical behavior of complex-shaped bridge construction processes in existing technologies. By establishing a bridge erection machine and bridge girder structure model that includes parameters of the highway bridge erection machine, bridge structure parameters, and parameters of the prestressed steel strands of the I-beams, and comprehensively calculating various verification loads based on this model, such as self-weight, bridge erection machine load, wind load, and prestressed steel strand load, it can more accurately simulate the stress conditions during actual construction, thereby achieving a full analysis of the mechanical behavior of complex-shaped bridge construction processes and providing a reliable basis for subsequent stress assessment.

[0017] Furthermore, this invention defines various working conditions in detail, covering complex situations such as the maximum stress on the cap beam under the action of the front support leg, the maximum stress on the end of the erected precast beam under the action of the middle support leg, the most unfavorable stress on the middle part of the erected precast beam under the action of the support leg, and the most unfavorable load on the erected precast beam under the action of the beam transport vehicle. Through in-depth analysis of these different working conditions, a comprehensive understanding of the stress state of the bridge during the erection process can be achieved, avoiding assessment biases caused by analysis of a single working condition, and effectively improving the accuracy and reliability of safety assessments.

[0018] Furthermore, this invention clarifies the conditions for determining the qualification of the bridge erection process using a bridge erecting machine. It comprehensively considers multiple key indicators, such as the maximum displacement of the bridge deformation, the maximum stress value of the prestressed I-beam, and the maximum compressive stress value of the cap beam, and compares these with preset deflection values, compressive strength design values, and tensile strength design values. Only when all conditions are met is the bridge erection process deemed qualified, thus strictly controlling construction quality, ensuring the safety and stability of the bridge during erection, and effectively reducing construction risks.

[0019] Furthermore, this invention formulates targeted construction optimization strategies based on the direction of the maximum displacement of bridge deformation. When the direction of the maximum displacement is transverse, temporary tie beams are added at the ends and middle of the concrete I-beam segments; when the direction of the maximum displacement is longitudinal, the cap beam is anchored to the temporary tie beams at the bottom of the I-beam segments using steel wire ropes. In addition, the number of temporary tie beams added in the middle of the I-beam segments is determined based on the transverse composite load stability coefficient, making the construction optimization strategy more precise and reasonable, effectively improving the stress condition of the bridge and enhancing construction quality. Attached Figure Description

[0020] Figure 1 This is a flowchart of the stress analysis method for a bridge with a slope curve and narrow precast beams under construction, according to an embodiment of the present invention. Figure 2 This is a flowchart illustrating the process of determining the qualification of the bridge erection machine's beam erection technology based on the bridge deformation displacement results and the bridge concrete stress results, as described in an embodiment of the present invention. Figure 3 This is a flowchart illustrating how a construction optimization strategy is determined based on the direction of the maximum displacement of bridge deformation, according to an embodiment of the present invention. Figure 4 This is a flowchart illustrating how to determine the number of temporary tie beams to be added to the middle of an I-beam segment based on the transverse composite load stability coefficient, according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0022] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0023] It should be noted that the data in this embodiment are all derived from a comprehensive analysis and evaluation of historical test data and corresponding historical test results from the three months prior to this test. Those skilled in the art will understand that the determination of the above-mentioned parameters for any single item in this invention can be achieved by selecting the value with the highest percentage based on the data distribution as the preset standard parameter, using weighted summation to obtain the value as the preset standard parameter, substituting each historical data point into a specific formula and using the value obtained from that formula as the preset standard parameter, or other selection methods, as long as the invention can clearly define different specific situations in the single-item judgment process through the obtained values.

[0024] Please see Figures 1 to 4 As shown, the flowcharts are as follows: a flowchart of the stress analysis method for constructing a bridge with a narrow precast beam with a slope curve according to an embodiment of the present invention; a flowchart of the present invention for determining the qualification of the bridge erection machine beam erection process based on the bridge deformation displacement results and the bridge concrete stress results; a flowchart of the present invention for determining the construction optimization strategy based on the direction of the maximum displacement of the bridge deformation; and a flowchart of the present invention for determining the number of temporary tie beams added in the middle of the I-beam segment based on the transverse composite load stability coefficient.

[0025] The stress analysis method for narrow-span precast beam bridges with sloping curves according to embodiments of the present invention includes: Step S1: Establish a bridge erection machine beam erection structure model based on structural material parameters, including highway bridge erection machine parameters, bridge structure parameters, and I-beam prestressed steel strand parameters. Step S2: Calculate and determine various verification loads acting on the bridge erecting machine and precast I-beams based on the structural model. The verification loads include self-weight, bridge erecting machine load, wind load, and prestressed steel strand load. Step S3: Analyze the stress on the bridge based on different working conditions, including working condition 1, working condition 2, working condition 3 and working condition 4. Step S4: Determine the qualification of the bridge erection machine's beam erection process based on the bridge deformation displacement results and the bridge concrete stress results. Step S5: Under the condition that the bridge girder erection process is qualified, determine the construction optimization strategy according to the direction of the maximum displacement of bridge deformation.

[0026] Specifically, the parameters of a highway bridge erecting machine include the steel specifications and dimensions of the upper chord, lower chord, diagonal / vertical braces, and bottom braces of the main truss standard section; the bridge structural parameters include structural components, concrete strength grade, design values ​​of axial compressive strength and axial tensile strength; and the parameters of the prestressed steel strands for the I-beams include the strand diameter, cross-sectional area, ultimate tensile strength, modulus of elasticity, number of strands, maximum tension force, maximum anchorage force, curvature, and synergistic effect coefficient.

[0027] Specifically, this invention utilizes Midas finite element software to establish a bridge erection machine beam structure model.

[0028] Specifically, working condition 1 refers to the maximum stress condition of the cap beam under the action of the front support leg, that is, when the bridge erecting machine is erecting the side beam, the pressure transmitted to the cap beam by the front support leg through the transverse track and sleepers is the greatest.

[0029] Specifically, condition 2 refers to the maximum stress condition at the end of the precast beam under the action of the middle support leg, that is, when the bridge erecting machine is erecting the side beam, the pressure transmitted from the middle support leg to the precast beam and cap beam through the transverse track and sleepers is at its maximum.

[0030] Specifically, working condition 3 represents the most unfavorable stress situation for the middle section of the erected precast beam under the action of the support legs, including the following situations: Condition 3-1: When the bridge erecting machine is in the beam feeding state, the tail support leg is at the first preset distance from the front end of the erected precast beam, and the pressure of the tail support leg transmitting force to the precast beam through the steel beam is at its maximum. Condition 3-2: The bridge erecting machine is in the beam feeding state. The position of the tail leg is the second preset distance from the front end of the erected precast beam. The tail leg transmits the force to the precast beam through the steel beam. The two tail legs exert the maximum force on the bridge deck. Condition 3-3: When the bridge erecting machine is in the span crossing state, the position of the tail leg is three preset distances away from the front end of the precast beam that has been erected. The tail leg transmits the force to the precast beam through the steel beam. The two tail legs exert the maximum force on the bridge deck. In working condition 3-4, the bridge erecting machine is in the span crossing state. The distance between the lateral track of the middle support leg of the bridge erecting machine and the front end of the precast beam has been preset to the fourth distance. The middle support leg transmits the data to the precast beam through the lateral track and sleepers. The two middle support legs have the maximum impact on the bridge deck.

[0031] In this embodiment of the invention, the first preset distance is 9m, the second preset distance is 12.5m, the third preset distance is 29.2m, and the fourth preset distance is 22m.

[0032] Specifically, condition 4 represents the most unfavorable load situation for the precast beams under the action of the beam transport vehicle. That is, the beam transport vehicle moves by means of steel rails erected on two adjacent precast beams. When the vehicle moves to the mid-span position of the precast beam, the bending moment generated on the precast beam is the greatest.

[0033] Specifically, the bridge erection machine's girder erection process is deemed qualified if and only if all of the following conditions are met: The maximum displacement of the bridge deformation is less than the preset deflection value; The maximum stress value of the prestressed I-beam is less than the first preset compressive strength design value; The maximum compressive stress value of the cap beam is less than the second preset tensile strength design value.

[0034] In this embodiment of the invention, the preset deflection value is 75 mm, which is set according to the deflection limit provisions of Article 6.5.3 of the "Design Specification for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts" (JTG3362-2018); the first preset compressive strength design value is 22.4 MPa, and the second preset tensile strength design value is 16.1 MPa, which is set according to the material strength limit provisions of Article 3.14 of the "Design Specification for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts" (JTG3362-2018).

[0035] Specifically, the construction optimization strategy is determined based on the direction of the maximum displacement of the bridge deformation, wherein... If the direction of the maximum deformation displacement is transverse, temporary tie beams are added at the ends and middle of the concrete I-beam segments; If the direction of the maximum deformation displacement is longitudinal, then steel wire ropes are used to anchor the cap beam to the temporary tie beam at the bottom of the I-beam.

[0036] Specifically, the number of temporary tie beams added to the middle of the I-beam segment is determined based on the stability coefficient of the transverse composite load. If the stability coefficient of the transverse composite load is less than the preset stability coefficient, then the number of temporary tie beams to be increased is determined to be the first preset number. If the stability coefficient of the transverse composite load is greater than or equal to the preset stability coefficient, then the number of temporary tie beams to be increased is determined to be the second preset number.

[0037] In this embodiment of the invention, the preset stability coefficient is 0.8, the first preset quantity is 2, and the second preset quantity is 1. However, the above values ​​are not limited to these, and those skilled in the art can adjust the above values ​​according to actual needs.

[0038] Specifically, the lateral composite load stability coefficient is determined by the lateral wind load and the lateral braking load. The lateral composite load stability coefficient = first weighting coefficient × lateral wind load / wind load threshold + second weighting coefficient × lateral braking load / braking load threshold.

[0039] In this embodiment of the invention, the first weighting coefficient is 0.5, the wind load threshold is 60 kN, the second weighting coefficient is 0.5, and the braking load threshold is 50 kN. However, the above values ​​are not limited to these values, and those skilled in the art can adjust the above values ​​according to actual needs.

[0040] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A stress analysis method for a narrow-span precast beam bridge with a sloping curve, characterized in that, include: A bridge erection machine beam erection structure model is established based on structural material parameters, including highway bridge erection machine parameters, bridge structure parameters, and I-beam prestressed steel strand parameters. Based on the structural model, various verification loads acting on the bridge erecting machine and the precast I-beam are calculated and determined. The verification loads include self-weight, bridge erecting machine load, wind load, and steel strand prestress load. The stress condition of the bridge is analyzed based on different working conditions, including working condition 1, working condition 2, working condition 3 and working condition 4. The qualification of the bridge erection machine's beam erection process is determined based on the bridge deformation displacement results and the bridge concrete stress results. Under the condition that the bridge girder erection process is qualified, the construction optimization strategy is determined according to the direction of the maximum displacement of bridge deformation.

2. The stress analysis method for bridges with narrow precast beams and sloping curves constructed according to claim 1, characterized in that, Condition 1 refers to the maximum stress condition of the cap beam under the action of the front outrigger, that is, when the bridge erecting machine is erecting the side beam, the pressure transmitted to the cap beam by the front outrigger through the transverse track and sleepers is at its maximum.

3. The stress analysis method for bridges with narrow precast beams and sloping curves as described in claim 2, characterized in that, Condition 2 refers to the maximum stress condition at the end of the precast beam under the action of the middle support leg. That is, when the bridge erecting machine is erecting the side beam, the pressure transmitted from the middle support leg to the precast beam and cap beam through the transverse track and sleepers is at its maximum.

4. The stress analysis method for bridges with narrow precast beams and sloping curves constructed according to claim 3, characterized in that, Condition 3 describes the most unfavorable stress situation for the middle section of the erected precast beam under the action of the support legs, including the following situations: Condition 3-1: When the bridge erecting machine is in the beam feeding state, the tail support leg is at the first preset distance from the front end of the erected precast beam, and the pressure of the tail support leg transmitting force to the precast beam through the steel beam is at its maximum. Condition 3-2: The bridge erecting machine is in the beam feeding state. The position of the tail leg is the second preset distance from the front end of the erected precast beam. The tail leg transmits the force to the precast beam through the steel beam. The two tail legs exert the maximum force on the bridge deck. Condition 3-3: When the bridge erecting machine is in the span crossing state, the position of the tail leg is three preset distances away from the front end of the precast beam that has been erected. The tail leg transmits the force to the precast beam through the steel beam. The two tail legs exert the maximum force on the bridge deck. In working condition 3-4, the bridge erecting machine is in the span crossing state. The distance between the lateral track of the middle support leg of the bridge erecting machine and the front end of the precast beam has been preset to the fourth distance. The middle support leg transmits the data to the precast beam through the lateral track and sleepers. The two middle support legs have the maximum impact on the bridge deck.

5. The stress analysis method for bridges with narrow precast beams and sloping curves constructed according to claim 4, characterized in that, Condition 4 represents the most unfavorable load situation for the precast beams under the action of the beam transport vehicle. That is, the beam transport vehicle moves by means of steel rails erected on two adjacent precast beams. When the vehicle moves to the mid-span position of the precast beam, the bending moment generated on the precast beam is the greatest.

6. The stress analysis method for bridges with narrow precast beams and sloping curves constructed according to claim 5, characterized in that, The bridge erection machine is deemed to have a qualified girder erection process if and only if all of the following conditions are met: The maximum displacement of the bridge deformation is less than the preset deflection value; The maximum stress value of the prestressed I-beam is less than the first preset compressive strength design value; The maximum compressive stress value of the cap beam is less than the second preset tensile strength design value.

7. The stress analysis method for narrow-span precast beam bridges with sloping curves as described in claim 6, characterized in that, The construction optimization strategy is determined based on the direction of the maximum displacement of the bridge deformation. If the direction of the maximum displacement of deformation is transverse, temporary tie beams are added at the ends and middle of the concrete I-beam segments.

8. The stress analysis method for bridges constructed with narrow precast beams and slope curves according to claim 7, characterized in that, If the direction of the maximum deformation displacement is longitudinal, then steel wire ropes are used to anchor the cap beam to the temporary tie beam at the bottom of the I-beam.

9. The stress analysis method for bridges with narrow precast beams and sloping curves constructed according to claim 8, characterized in that, The number of temporary tie beams to be added in the middle of the I-beam segment is determined based on the stability coefficient of the transverse composite load. If the stability coefficient of the transverse composite load is less than the preset stability coefficient, then the number of temporary tie beams to be increased is determined to be the first preset number. If the stability coefficient of the transverse composite load is greater than or equal to the preset stability coefficient, then the number of temporary tie beams to be increased is determined to be the second preset number.

10. The stress analysis method for a bridge with a narrow precast beam and sloping curve under construction according to claim 9, characterized in that, The stability coefficient of the lateral composite load is determined by the lateral wind load and the lateral braking load.

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