A frame bridge crack control method and system

Abstract

The application provides a frame bridge crack control method and system, relates to the railway bridge engineering technical field, and comprises the following steps: acquiring basic data, performing modeling processing according to the basic data to obtain a finite element stress model; performing simulation according to the finite element stress model to obtain a set of mechanical performance parameters; performing construction risk stage evaluation according to the set of mechanical performance parameters to construct a core parameter mathematical model; performing finite element calculation on target parameters according to the core parameter mathematical model to obtain a support system core parameter configuration; comparing the core parameter configuration with on-site monitoring data and checking and rechecking to obtain a construction period crack control scheme. The application initiatively regulates and controls the stress distribution of the structure in the construction stage from the essence of the stress system, realizes the technical scheme of crack active control through structure system optimization, and effectively controls the construction period crack problem of the frame bridge.

Description

Technical Field

[0001] This invention relates to the field of railway bridge and culvert engineering technology, specifically to a method and system for controlling cracks in frame bridges and culverts. Background Technology

[0002] Frame bridges and culverts are widely used underpass structures in railway and highway engineering. Their construction involves multiple stages, including excavation, structural pouring, partial backfilling, and overall backfilling. The stress system changes significantly at each stage, with the most unfavorable stress state occurring when the excavation is complete but the soil on both sides has not yet been backfilled. At this point, the web plate is in a cantilevered bending state without soil support on one or both sides, resulting in large bending moments and concentrated tensile stress at the bottom. This makes it highly susceptible to cracks at the bottom or center of the web plate, leading to durability problems such as concrete cover detachment, steel corrosion, and water leakage, threatening the structure's safety in later use.

[0003] In current engineering practice, existing construction control methods for frame bridges and culverts focus on the combination of dead load and live load during the operation period, ignoring the impact of sudden changes in the stress system during the construction phase. The analysis of temporary working conditions is insufficient, and it is impossible to start from the essence of the stress system and actively regulate the stress distribution of the structure during the construction phase, resulting in limitations in the design of crack control during the construction phase of frame bridges and culverts.

[0004] In view of the problems of the existing technology, there is an urgent need for a method and system for controlling cracks in frame bridges and culverts. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for controlling cracks in frame bridges and culverts, so as to improve the above-mentioned problems. To achieve the above objective, the technical solution adopted by this invention is as follows:

[0006] Firstly, this application provides a method for controlling cracks in frame bridges and culverts, including:

[0007] Acquire basic data, which includes the geometric parameters, material parameters, foundation parameters, and construction stage load parameters of the frame bridge and culvert.

[0008] Based on the aforementioned basic data, a modeling process is performed, and a finite element stress model is obtained by conducting finite element analysis on the culvert space.

[0009] Simulations were performed based on the finite element stress model. By simulating different construction conditions and extracting the bending moment and tensile stress distribution of the control section of the web plate under each condition, a set of mechanical performance parameters was obtained.

[0010] Based on the set of mechanical performance parameters, a phased assessment of construction risk is conducted. By performing parameter analysis on the support structure of the selected construction condition, a mathematical model of the core parameters is constructed.

[0011] Based on the mathematical model of the core parameters, the target parameters are calculated by finite element method. By introducing a temporary cross bracing system and adjusting the cross bracing cross-sectional area, spacing, number of layers and installation elevation, the core parameter configuration of the support system is obtained.

[0012] The core parameter configurations are compared with and verified against on-site monitoring data to obtain a crack control scheme for the construction period.

[0013] Secondly, this application also provides a crack control system for frame bridges and culverts, comprising:

[0014] The acquisition module is used to acquire basic data, which includes the geometric parameters, material parameters, foundation parameters, and construction stage load parameters of the frame bridge and culvert.

[0015] The processing module is used to perform modeling processing based on the basic data, and to obtain a finite element stress model by performing finite element analysis on the culvert space.

[0016] The simulation module is used to perform simulation based on the finite element stress model. By simulating different construction conditions and extracting the bending moment and tensile stress distribution of the control section of the web plate under each condition, a set of mechanical performance parameters is obtained.

[0017] The construction module is used to conduct phased assessments of construction risks based on the set of mechanical performance parameters, and to construct a mathematical model of core parameters by performing parameter analysis on the support structure of the selected construction conditions.

[0018] The calculation module is used to perform finite element calculations on the target parameters based on the mathematical model of the core parameters. By introducing a temporary cross bracing system and adjusting the cross bracing cross-sectional area, spacing, number of layers and installation elevation, the core parameter configuration of the support system is obtained.

[0019] The output module is used to compare and verify the core parameter configuration with the on-site monitoring data to obtain a crack control plan during the construction period.

[0020] The beneficial effects of this invention are as follows:

[0021] The present invention discloses a method and system for controlling cracks in frame bridges and culverts. During the construction phase, a detachable temporary transverse support system is set up to actively adjust the stress state of the structure, transforming the structure from a single cantilever bending system to a multi-support stress system. This significantly reduces the maximum bending moment and tensile stress in the web, effectively controlling the development of cracks during construction. Actual measurement and calculation results show that this method can effectively prevent early cracking and crack propagation during construction, improving the overall safety and durability of the structure.

[0022] This invention introduces the concept of "structural stress adjustment" into crack control during the construction period, and constructs a systematic crack control technology system based on stress analysis during the construction stage. This system achieves crack prevention and control throughout the entire process from the design stage, construction stage to the construction monitoring stage through a complete technical process of "numerical analysis - risk identification - temporary support - dynamic control". Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a method for controlling cracks in a frame bridge and culvert as described in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of a frame bridge and culvert crack control system as described in an embodiment of the present invention;

[0026] Figure 3 This is a plan view of a frame bridge culvert cross bracing system as described in an embodiment of the present invention;

[0027] Figure 4 This is an elevation layout diagram of a frame bridge culvert cross bracing system as described in an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of a frame bridge and culvert foundation replacement method as described in an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0031] Before disclosing the embodiments of the present invention, the technical problems solved by the present invention are described: In existing construction designs, in order to avoid cracks during construction, design units often passively resist cracking by increasing permanent reinforcement or improving concrete strength, without addressing the cracking problem from the perspective of the stress system, resulting in material waste and inefficient stress distribution, and poor economic efficiency; Existing control measures usually rely on "timely backfilling" or "segmented symmetrical construction" to maintain structural stress balance, but these are easily affected by factors such as weather, process connection, and equipment conditions at the construction site, making it difficult to ensure the consistency of the construction sequence and posing a significant risk of cracking; After the crack width exceeds the specification limit, it is difficult to reduce the hidden dangers through later repair or grouting, making quality control difficult and affecting the long-term service safety of frame bridges and culverts.

[0032] Example 1:

[0033] This embodiment provides a method for controlling cracks in frame bridges and culverts.

[0034] The specific implementation process is as follows:

[0035] See Figure 1 The figure shows that the method includes steps S100 to S600.

[0036] Step S100: Obtain basic data, which includes the geometric parameters, material parameters, foundation parameters, and construction stage load parameters of the frame bridge and culvert.

[0037] Specifically, the acquisition of basic data needs to comprehensively cover four core dimensions of the frame bridge and culvert: construction structure, construction materials, foundation, and construction loads. Geometric parameters are extracted based on design drawings, including the culvert's clear span. Culvert clearance height Top plate thickness Base plate thickness Side wall thickness Web thickness and base width Material parameters are referenced from standards and design documents. Concrete material is input using an elastic material model, and its elastic modulus is... Poisson's ratio is Weight according to material density The calculations used equivalent reinforcement to determine relevant parameters for the steel bars; the foundation parameters were obtained through field investigation and geotechnical testing, with the foundation reaction coefficient being the core parameter. It is used to characterize the soil's constraint capacity; the load parameters during the construction phase are combined with the construction organization design, including the structure's self-weight. Backfill height Earth pressure coefficient Soil weight The calculation basis for lateral earth pressure is determined according to a linear distribution law. All data must be reviewed and verified to ensure consistency with engineering realities and specification requirements, providing accurate data support for subsequent modeling and stress analysis, avoiding distortion of simulation results due to parameter errors, and ensuring the scientific validity and reliability of the crack control scheme.

[0038] Step S200: Model the data based on the basic data and obtain the finite element stress model by performing finite element analysis on the culvert space.

[0039] Specifically, a three-dimensional geometric model of the culvert is established based on the geometric parameters, material parameters, foundation parameters, and construction stage load parameters of the bridge and culvert within the basic data framework. The main structure is discretized using shell or solid elements, and the mesh is refined for the stress concentration areas in the web and those connected to the bottom slab and side walls. Concrete parameters are input according to the elastic material model, and the effect of steel reinforcement is incorporated through equivalent reinforcement. An elastic foundation model is used to simulate the interaction between the bottom slab and the foundation, introducing… Calculate the vertical spring stiffness of the base plate nodes, considering the area affected by the nodes. The finite element stress model was constructed by applying the structure's self-weight and linearly distributed lateral earth pressure in stages. This accurately reproduced the structural characteristics and stress environment of the frame bridge and culvert, and mesh refinement improved the accuracy of bending moment and tensile stress calculations, providing a high-fidelity analysis platform for subsequent working condition simulations.

[0040] Step S300: Perform simulation based on the finite element stress model. By simulating different construction conditions and extracting the bending moment and tensile stress distribution of the control section of the web plate under each condition, a set of mechanical performance parameters is obtained.

[0041] Specifically, such as Figure 5 As shown, the bottom of the foundation replacement is a graded crushed stone cushion layer, which is set with a 1:1 slope. Based on the finite element stress model, three typical construction conditions, namely "excavation without backfilling", "partial backfilling" and "full backfilling", are simulated. The bending moment of the control section of the web under each condition is extracted by calculation. Tensile stress The data, including distribution data, forms a parameter set encompassing the mechanical responses at different backfilling stages. The focus is on analyzing stress concentration under the "excavation without backfilling" condition to identify high-risk cracking areas. A systematic understanding of the structural mechanics changes throughout the entire construction process is achieved, allowing for precise location of the web bending moment. With tensile stress Peak operating conditions provide data for risk assessment and supporting design.

[0042] Step S400: Conduct a construction risk assessment based on the set of mechanical performance parameters. By performing parameter analysis on the support structure of the selected construction condition, construct a mathematical model of the core parameters.

[0043] Specifically, a comparative analysis is conducted on the set of mechanical performance parameters, taking the bending moment of the web as an example. Peak value, tensile stress Concentration and crack width The calculation result serves as a risk assessment indicator. When the crack width reaches or exceeds the specification limit under a certain working condition... At this point, the construction is identified as being in a risky phase. Based on the stress characteristics of this risky phase, a mathematical model of core parameters is constructed, encompassing the axial stiffness of the support. , reaction force and crack width Control correlation formulas. Accurately identify key construction risk points, establish quantitative relationships between parameters and crack control, and provide clear objectives and calculation frameworks for subsequent support system optimization.

[0044] Step S500: Perform finite element calculations on the target parameters based on the mathematical model of the core parameters. By introducing a temporary cross bracing system and adjusting the cross bracing cross-sectional area, spacing, number of layers, and installation elevation, the core parameter configuration of the support system is obtained.

[0045] Specifically, a temporary cross bracing system is introduced into the finite element model, treating the cross bracing as an axially stressed component or an elastic support element. The cross-sectional area of ​​the cross bracing is adjusted iteratively. Longitudinal spacing Number of layers And the installation elevation, calculate the bending moment of the web plate under different parameter combinations. Tensile stress and crack width When the calculation result satisfies At that time, the corresponding support stiffness, cross-sectional dimensions, number of layers, and spacing are determined to form the core parameter configuration of the support system. This achieves precise optimization of the support parameters, transforming the structure from cantilever bending to multi-point stress, significantly reducing tensile stress and crack width in the web, and avoiding material waste caused by excessive reinforcement or increased concrete strength.

[0046] Step S600: Compare and verify the core parameter configuration with the on-site monitoring data to obtain the crack control scheme during the construction period.

[0047] Specifically, the core parameter configurations are applied to actual construction. Real-time monitoring of web strain, relative displacement of sidewalls, and crack width data is achieved using concrete strain gauges, displacement gauges, and crack width observation instruments. The measured data from the field are compared with the finite element calculation results to verify the model's accuracy. If deviations are found, the support parameters are adjusted and recalculated. Combining monitoring feedback and calculation results, a complete construction-period crack control scheme is developed, including support layout, construction sequence, and removal timing, clearly defining the installation and removal process of cross braces. This achieves precise matching between theoretical calculations and actual field conditions, dynamically controlling construction risks, ensuring crack width is strictly controlled within the specified limits, improving structural durability and construction safety, while simplifying the construction process and reducing reliance on "timely backfilling."

[0048] Further, step S200 includes steps S210 to S230.

[0049] Step S210: Based on the geometric parameters of the basic data, construct a three-dimensional geometric model of the culvert by inputting the structural dimension parameters of the top plate, bottom plate, side walls and web plate;

[0050] Step S220: Discretely analyze the main structural units of the culvert based on the three-dimensional geometric model of the culvert. By selecting the unit type, dividing the mesh, selecting material parameters, and simulating the foundation and boundary conditions, a modeling parameter set is obtained.

[0051] Step S230: Based on the three-dimensional geometric model of the culvert and the modeling parameter set, perform finite element analysis on the culvert space to obtain the finite element stress model of the frame bridge culvert during the construction stage.

[0052] Specifically, based on the design drawings of the frame bridge and culvert, input the core geometric parameters completely: culvert clear span Culvert clearance height Top plate thickness Base plate thickness Side wall thickness Web thickness and base width A full-size three-dimensional geometric model of the culvert, including the top slab, bottom slab, side walls, central web slab, and foundation, is constructed according to the design dimensions to ensure that the model is completely consistent with the geometry of the actual structure, thereby guaranteeing the authenticity and reliability of the finite element model.

[0053] The main structure of the culvert is discretized using shell or solid elements. In stress concentration areas where the web connects to the bottom slab and side walls, the mesh size is refined. Non-stress concentration areas are divided using standard mesh sizes to balance computational accuracy and efficiency. Mesh refinement in stress concentration areas improves the accuracy of bending moment and tensile stress calculations, providing precise data support for subsequent stress analysis. Concrete is input as an elastic material model, with elastic modulus... Poisson's ratio Material density Values ​​are taken according to design specifications, and the reinforcing bars are integrated into the model through equivalent cross-sectional reinforcement; an elastic foundation model is used to characterize the interaction between the slab and the foundation, and the vertical spring stiffness of the slab joints is calculated:

[0054] ;

[0055] in Vertical spring stiffness of the base plate node; This is the soil reaction coefficient; The node influence area constrains the redundant degrees of freedom other than the vertical displacement of the base plate; the above parameters are integrated to form a modeling parameter set that includes element type, mesh size, material properties, and foundation constraints.

[0056] Finite element analysis was performed on the culvert's three-dimensional geometric model and modeling parameter set, and the structural self-weight was applied. Lateral loads on the backfill soil are applied in stages according to the construction phases:

[0057] ;

[0058] in, It is a lateral load; To calculate depth; For depth Lateral load at the location; This is the earth pressure coefficient; The soil weight; To determine the backfill height, a construction phase analysis module is set up to simulate the stress changes of the structure throughout the entire process from foundation pit excavation to backfill completion, ultimately generating a finite element stress model of the frame bridge and culvert during the construction phase. This fully simulates the load and constraint changes during the construction phase, ensuring that the finite element stress model accurately reflects the stress state of the structure throughout the entire construction process.

[0059] Further, step S300 includes steps S310 to S330.

[0060] Step S310: Design construction conditions based on the basic data, establish a simulation scheme based on the foundation pit backfilling state, and obtain different construction conditions;

[0061] Step S320: Simulate the finite element stress model according to the construction conditions. By simulating the construction conditions of excavation without backfilling, partial backfilling, and full backfilling on both sides of the foundation pit, the simulation results are obtained.

[0062] Step S330: Based on the simulation results, extract the bending moment and tensile stress distribution of the web control section under the construction condition to obtain a set of mechanical performance parameters.

[0063] Specifically, based on the geometric parameters, material parameters, foundation parameters, and construction stage load parameters of the frame bridge and culvert, the construction conditions are designed, and the typical construction conditions of "excavation without backfilling", "partial or unilateral backfilling", and "full backfilling on both sides" are simulated in the model: Condition A: Excavation of the foundation pit is completed, but backfilling is not carried out on both sides ( , Condition B: Backfill height; Working condition B: Single-sided or partial backfill ( Condition C: Backfill height is set according to actual construction conditions (partial or unilateral backfill height). (This refers to the backfill height on both sides); clearly define the load application range, backfill height parameters, and constraints for each working condition, form a standardized construction working condition plan, and improve the scientific nature of stress analysis during the construction stage by replacing traditional experience-based judgment with simulation.

[0064] Substitute the three types of construction conditions into the finite element stress model in sequence:

[0065] Condition A: Only the structure's self-weight is applied, with no lateral earth pressure constraints;

[0066] Condition B: Applying structural self-weight + unilateral / local lateral earth pressure, according to... Perform the calculation:

[0067] ;

[0068] in, It is a lateral load; To calculate depth; For depth Lateral load at the location; This is the earth pressure coefficient; The soil weight; This refers to the height of backfill in a localized or unilateral area.

[0069] Condition C: Applying the structure's self-weight + bilateral full-coverage lateral earth pressure (according to...) Substitute into the above formula):

[0070] ;

[0071] in, It is a lateral load; To calculate depth; For depth Lateral load at the location; This is the earth pressure coefficient; The soil weight; This refers to the backfill height on both sides.

[0072] The bending moment of the control section of the web plate under each working condition is extracted from the simulation results; according to the section bending theory:

[0073] ;

[0074] in, Tensile stress at the tension edge; To control the bending moment of the cross section; The distance from the tensioned edge to the neutral axis; It measures the moment of inertia of the cross section; integrates the bending moment values, tensile stress magnitudes and distribution patterns of different working conditions and different control sections to form a set of mechanical performance parameters. It accurately extracts the core mechanical parameters of the web, providing a quantitative basis for crack risk assessment, fully covering the working conditions of key construction stages, and comprehensively capturing the structural stress change patterns.

[0075] Further, step S400 includes steps S410 to S430.

[0076] Step S410: Conduct a risk assessment based on the set of mechanical performance parameters, compare the crack width with the preset limit value of crack width, and obtain the crack risk assessment result during the construction period.

[0077] Step S420: Based on the construction period crack risk assessment results, the construction conditions are screened and processed. By analyzing the stress state and lateral constraint conditions of the web plate, the construction period crack control conditions are obtained.

[0078] Step S430: Perform finite element analysis based on the stiffness, cross-section, and number of layers of the supporting structure under the control condition to construct a mathematical model of the core parameters.

[0079] Specifically, the crack width is calculated according to the standard method:

[0080] ;

[0081] in, The width of the crack; The average crack spacing; The average strain of the steel reinforcement; The average strain of the concrete was calculated; the crack width in the web was calculated under various working conditions, and the preset limit value for crack width in the current bridge and culvert engineering specifications was retrieved. Calculate the values ​​for each working condition and Compare them one by one; if This is classified as a high-risk working condition; if The condition was determined to be low-risk, and a crack risk assessment result was generated during the construction period to quantify the crack risk level and avoid subjectivity in risk judgment.

[0082] Comparing the stress state of the web under different working conditions, the focus is on analyzing the effect of lateral constraints (backfill effect) on bending moment. Tensile stress The impact of the stress was investigated; peak bending moment and tensile stress conditions were screened out, and combined with the crack width exceeding the limit, condition A was determined: "the foundation pit excavation is completed and the two sides are not backfilled", which is the crack control condition during the construction period. Under this condition, the web plate is in a cantilever bending state, and the crack risk is the highest. The control condition was accurately identified, which makes the subsequent support design more targeted.

[0083] Based on the mechanical performance parameters of the control conditions, a mathematical model of the core parameters is constructed:

[0084] Cross brace stiffness model:

[0085] ;

[0086] in, For the stiffness of the cross brace; The elastic modulus of the cross brace material; The cross-sectional area of ​​the cross brace; Calculate the length of the cross brace.

[0087] Crack width control model:

[0088] ;

[0089] in, The width of the crack; The average crack spacing; The average strain of the steel reinforcement; The average strain of the concrete; Preset a limit for the crack width.

[0090] Bending moment adjustment model:

[0091] ;

[0092] in, This refers to the bending moment when there is no support. To set the target bending moment after support; The bending moment value is reduced to provide support; by linking the relationship between the cross brace parameters and the crack width and bending moment through the model, a mathematical model of the core parameters is constructed to provide a theoretical basis for the optimization of the temporary support system.

[0093] Further, step S500 includes steps S510 to S530.

[0094] Step S510: Calculate the axial stiffness according to the mathematical model of the core parameters. By substituting the elastic modulus, cross-sectional area and length of the cross brace material, the axial stiffness parameters are obtained.

[0095] Step S520: Calculate the support reaction force based on the axial stiffness parameters, and perform structural analysis in conjunction with the lateral relative displacement of the structure during the construction stage to obtain the support reaction force value.

[0096] Step S530: Based on the axial stiffness parameters and the support reaction force values, a temporary cross bracing system is introduced, and the cross bracing cross-sectional area, spacing, number of layers, and installation elevation are adjusted for finite element calculation. The calculation results are then integrated to obtain the core parameter configuration of the support system.

[0097] Specifically, such as Figure 3 The diagram shows the semi-plane and semi-base top plan layout of the transverse bracing system. After the main structure of the culvert is poured and the concrete strength reaches more than 70% of the design strength, a temporary transverse bracing system is arranged between the two side walls inside the culvert. The bracing can be made of steel pipes, H-beams, or precast concrete members, and both ends are fixed to the side walls by pre-embedded anchor plates, steel sleeves, or expansion bolts. Figure 4 As shown, the top of the cross brace is the bottom line of the trench. From the bottom line of the trench, the trench is filled with backfill soil, a 30cm thick crushed stone cushion layer, and a 20cm thick C30 concrete layer, respectively. For structures with large spans or deep foundation pits, vertical elastic foundation beams or diagonal stiffening members can be installed below the cross brace to enhance the overall rigidity and stability.

[0098] The support system should be arranged in rows, with longitudinal spacing generally controlled between 1.5 and 2.0 meters. The stiffness, cross-section, and number of layers of the cross braces should be determined by finite element analysis to ensure that the width of web cracks is controlled within the specified limits during critical construction stages. The cross brace material should be determined: steel pipe, H-beam, or precast concrete members, and its elastic modulus should be obtained. The cross brace cross-sectional specifications (such as steel pipe diameter and H-beam type) should be initially selected, and the cross-sectional area of ​​the cross braces should be calculated. The calculated length of the cross braces should be determined according to the clear span of the culvert. Temporary cross braces should be equivalent to axially loaded members or elastic support units, and their equivalent axial stiffness should be determined by the following formula:

[0099] ;

[0100] in, For axial stiffness; It is the elastic modulus; The cross-sectional area of ​​the cross brace; Calculate the length of the cross brace.

[0101] Based on axial stiffness parameters, a collaborative stress analysis model of the "frame bridge / culvert main body - temporary cross bracing" is established to clarify the force transmission path between the two, focusing on simulating the stress response of the cantilever bending region of the web. The lateral relative displacement of the structure under the control conditions is extracted from the finite element model. According to the formula for elastic support reaction force:

[0102] ;

[0103] in, To support the reaction force; For axial stiffness; This refers to lateral relative displacement. In construction monitoring, changes in structural stress can be fed back in real time through support reactions, facilitating quality management and risk warning. For extreme conditions such as peak pouring loads and critical demolding states, support reactions are specifically calculated to ensure coverage of stress requirements throughout the entire construction cycle and achieve dynamic control throughout the entire process.

[0104] The distribution pattern of the support reaction force was analyzed to determine its effect on offsetting the bending moment of the web, providing direction for parameter adjustment. The temporary cross bracing system was equivalent to an elastic support element and introduced into a finite element model. The cross braces were initially arranged at longitudinal spacings of 1.5–2.0 m. A three-dimensional finite element model was established, and the axial stiffness parameters were... With support reaction force value As input conditions, a three-dimensional refined finite element model including the main body of the bridge and culvert, temporary cross bracing, and foundation is constructed to fully restore the structural mechanical properties and boundary conditions, and the mesh is refined in the stress concentration area of ​​the web.

[0105] Parameter Adjustment and Simulation Calculation: Key parameters were optimized using the controlled variable method: Cross-sectional area: 3-5 sets of cross-bracing sections of different sizes were selected for simulation to match the support reaction requirements; Longitudinal spacing: Adjusted according to the recommended range of 1.5-2.0m in the specification to balance the uniformity of stress and the convenience of construction; Number of layers and installation elevation: Based on the peak moment distribution of the web, the number of cross-bracing layers and installation position were optimized to ensure accurate matching between the stress points and stress concentration areas, forming a calculable and controllable temporary stress structure throughout the construction process, greatly reducing the uncertainty and safety risks during the construction stage, and ensuring structural stability.

[0106] Index analysis and parameter selection: For each parameter combination, analyze indicators such as structural stress distribution, maximum lateral deformation, and crack width, with "crack width" as the key parameter. With the goal of minimizing structural deformation and optimizing construction costs, the optimal combination of parameters was selected.

[0107] Develop a core configuration plan: Integrate the calculation results, clarify the cross-sectional dimensions of the horizontal braces, the longitudinal spacing, the number of layers, and the installation elevation, and form a core parameter configuration report for the support system that can be directly used for construction.

[0108] The temporary cross bracing system enables proactive crack control during the construction of frame bridges and culverts, significantly improving structural safety and resolving the issue of excessive crack width during construction. Simultaneously, it can reduce steel reinforcement usage by 10%–25%, avoiding excessive increases in concrete strength without requiring additional permanent reinforcement or higher concrete strength. The support components can be reused in multiple culverts or construction phases, reducing material costs and extending construction time. After construction, it can be quickly dismantled without affecting subsequent backfilling and roadbed restoration. Furthermore, the parameter configuration scheme is applicable to frame bridge and culvert projects with different spans and geological conditions, demonstrating strong versatility.

[0109] Further, step S600 includes steps S610 to S630.

[0110] Step S610: Monitor the strain, displacement and crack width data at the construction site according to the crack control conditions during the construction period to obtain on-site monitoring data;

[0111] Step S620: Compare and verify the on-site monitoring data with the core parameter configuration to obtain the verification analysis results;

[0112] Step S630: Based on the verification analysis results and the core parameter configuration, optimization processing is performed, and the crack width is limited and optimized based on preset limits to obtain a crack control scheme during construction.

[0113] Specifically, based on the control conditions and risk areas, monitoring points are set up in areas prone to cracking in the web (the junction of the bottom and the foundation, and the central area) and near the temporary cross bracing; concrete strain gauges are installed to monitor the strain changes in the web, displacement gauges are set up to monitor the relative displacement of the two side walls, and crack widths are recorded in real time using crack microscopes or crack width measuring instruments; monitoring data are collected regularly according to the construction progress (excavation of the foundation pit, installation of supports, and backfilling construction) to form a field monitoring database.

[0114] Compare the on-site monitoring data with the finite element model calculation results one by one; check the deviation between the model calculation values ​​and the measured values, and if the deviation exceeds the standard, adjust the support stiffness in the model. Longitudinal spacing and number of floors The method involves iterative parameter calculations until the control requirements are met, thereby achieving dynamic control and risk warning of cracks during construction. The experimental and calculation results show that this method can effectively prevent early cracking and crack propagation during construction, and improve the overall safety and durability of the structure.

[0115] Based on the deviation analysis results, the rationality of the core parameter configuration of the support system is reviewed, and a verification analysis report is generated. If the measured crack width is close to... Fine-tune the stiffness of the cross brace Based on real-time monitoring data and a revised model, the installation sequence of supports is dynamically optimized. On-site monitoring enables visualization of the stress state throughout the construction process, ultimately forming a complete construction-period crack control scheme that includes support parameters, installation procedures, monitoring frequency, and adjustment plans. This scheme ensures that crack width is always controlled within the specified limits, forming a systematic crack control technology system based on stress analysis, centered on temporary support control, and guaranteed by dynamic monitoring and iterative optimization. The final scheme is both scientific and feasible, providing comprehensive guidance for on-site construction and ensuring structural durability and safety.

[0116] Example 2:

[0117] like Figure 2 As shown in the figure, this embodiment provides a crack control system for frame bridges and culverts. The system includes:

[0118] The acquisition module 101 is used to acquire basic data, which includes the geometric parameters, material parameters, foundation parameters, and construction stage load parameters of the frame bridge and culvert.

[0119] Processing module 102 is used to perform modeling processing based on the basic data, and to obtain a finite element stress model by performing finite element analysis on the culvert space;

[0120] The simulation module 103 is used to perform simulation based on the finite element stress model. By simulating different construction conditions and extracting the bending moment and tensile stress distribution of the control section of the web plate under each condition, a set of mechanical performance parameters is obtained.

[0121] The construction module 104 is used to conduct a construction risk stage assessment based on the set of mechanical performance parameters, and to construct a mathematical model of core parameters by performing parameter analysis on the support structure of the selected construction condition.

[0122] The calculation module 105 is used to perform finite element calculations on the target parameters based on the mathematical model of the core parameters. By introducing a temporary cross bracing system and adjusting the cross bracing cross-sectional area, spacing, number of layers and installation elevation, the core parameter configuration of the support system is obtained.

[0123] The output module 106 is used to compare and verify the core parameter configuration with the on-site monitoring data to obtain a crack control scheme during the construction period.

[0124] In one specific embodiment of the present invention, the processing module 102 includes:

[0125] The first processing unit is used to construct a three-dimensional geometric model of the culvert by inputting the structural dimension parameters of the top plate, bottom plate, side walls and web plate based on the geometric parameters of the basic data.

[0126] The second processing unit is used to perform discrete analysis on the main structural units of the culvert based on the three-dimensional geometric model of the culvert. By selecting the unit type, dividing the mesh, selecting material parameters, and simulating the foundation and boundary conditions, a modeling parameter set is obtained.

[0127] The third processing unit is used to perform finite element analysis on the culvert space based on the culvert's three-dimensional geometric model and the modeling parameter set, to obtain the finite element stress model of the frame bridge culvert during the construction stage.

[0128] In one specific embodiment of the present invention, the simulation module 103 includes:

[0129] The first simulation unit is used to design construction conditions based on the basic data, establish simulation schemes based on the foundation pit backfilling status, and obtain different construction conditions.

[0130] The second simulation unit is used to simulate the finite element stress model according to the construction conditions. The simulation results are obtained by simulating the construction conditions of excavation without backfilling, partial backfilling, and full backfilling on both sides of the foundation pit.

[0131] The third simulation unit is used to extract the bending moment and tensile stress distribution of the web control section under the construction condition based on the simulation results, and obtain a set of mechanical performance parameters.

[0132] In one specific embodiment of the present invention, the construction module 104 includes:

[0133] The first building unit is used to conduct a risk assessment based on the set of mechanical performance parameters, compare and analyze the crack width with the preset limit value of crack width, and obtain the crack risk assessment result during the construction period.

[0134] The second building unit is used to screen the construction conditions based on the construction period crack risk assessment results, and to obtain the construction period crack control conditions by analyzing the stress state and lateral constraint conditions of the web plate.

[0135] The third building unit is used to perform finite element analysis based on the stiffness, cross-section, and number of layers of the supporting structure under the control conditions, and to build a mathematical model of the core parameters.

[0136] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling cracks in frame bridges and culverts, characterized in that, include: Acquire basic data, which includes the geometric parameters, material parameters, foundation parameters, and construction stage load parameters of the frame bridge and culvert. Based on the aforementioned basic data, a modeling process is performed, and a finite element stress model is obtained by conducting finite element analysis on the culvert space. Simulations were performed based on the finite element stress model. By simulating different construction conditions and extracting the bending moment and tensile stress distribution of the control section of the web plate under each condition, a set of mechanical performance parameters was obtained. Based on the set of mechanical performance parameters, a phased assessment of construction risk is conducted. By performing parameter analysis on the support structure of the selected construction condition, a mathematical model of the core parameters is constructed. Based on the mathematical model of the core parameters, the target parameters are calculated by finite element method. By introducing a temporary cross bracing system and adjusting the cross bracing cross-sectional area, spacing, number of layers and installation elevation, the core parameter configuration of the support system is obtained. The core parameter configurations are compared with and verified against on-site monitoring data to obtain a crack control scheme for the construction period.

2. The method for controlling cracks in frame bridges and culverts according to claim 1, characterized in that, Based on the aforementioned basic data, modeling is performed, and a finite element stress model is obtained by conducting finite element analysis on the culvert space, including: Based on the geometric parameters of the basic data, a three-dimensional geometric model of the culvert is constructed by inputting the structural dimension parameters of the top slab, bottom slab, side walls, and web. Based on the three-dimensional geometric model of the culvert, the main structural units of the culvert are discretized and analyzed. By selecting the unit type, dividing the mesh, selecting material parameters, and simulating the foundation and boundary conditions, the modeling parameter set is obtained. Based on the 3D geometric model of the culvert and the modeling parameter set, a finite element analysis of the culvert space is performed to obtain the finite element stress model of the frame bridge culvert during the construction stage.

3. The method for controlling cracks in frame bridges and culverts according to claim 1, characterized in that, Simulations were performed based on the finite element stress model. By simulating different construction conditions and extracting the bending moment and tensile stress distribution of the control section of the web under each condition, a set of mechanical performance parameters was obtained, including: Based on the aforementioned basic data, construction conditions are designed, and simulation schemes are established based on the backfilling status of the foundation pit to obtain different construction conditions. The finite element stress model was simulated based on the construction conditions. The simulation results were obtained by simulating the construction conditions of excavation without backfilling, partial backfilling, and full backfilling on both sides of the foundation pit. Based on the simulation results, the bending moment and tensile stress distribution of the control section of the web under the construction conditions are extracted to obtain a set of mechanical performance parameters.

4. The method for controlling cracks in frame bridges and culverts according to claim 1, characterized in that, Based on the set of mechanical performance parameters, a phased assessment of construction risk is conducted. This involves parameter analysis of the support structure under selected construction conditions to construct a mathematical model of core parameters, including: Risk assessment is conducted based on the set of mechanical performance parameters. The crack width is compared and analyzed with the preset limit value of crack width to obtain the crack risk assessment result during the construction period. Based on the construction period crack risk assessment results, the construction conditions were screened and processed. By analyzing the stress state and lateral constraint conditions of the web plate, the crack control conditions during the construction period were obtained. Finite element analysis was performed based on the stiffness, cross-section, and number of stories of the supporting structure under the control conditions to construct a mathematical model of the core parameters.

5. The method for controlling cracks in frame bridges and culverts according to claim 1, characterized in that, Based on the mathematical model of the core parameters, finite element calculations are performed on the target parameters. By introducing a temporary cross bracing system and adjusting the cross bracing cross-sectional area, spacing, number of layers, and installation elevation, the core parameter configuration of the support system is obtained, including: The axial stiffness is calculated based on the mathematical model of the core parameters. The axial stiffness parameters are obtained by substituting the elastic modulus, cross-sectional area and length of the cross brace material. The support reaction force is calculated based on the axial stiffness parameters, and the structural analysis is performed in conjunction with the lateral relative displacement of the structure during the construction stage to obtain the support reaction force value. Based on the axial stiffness parameters and the support reaction force values, a temporary cross bracing system is introduced, and the cross bracing cross-sectional area, spacing, number of layers, and installation elevation are adjusted for finite element calculation. The calculation results are then integrated to obtain the core parameter configuration of the support system.

6. The method for controlling cracks in frame bridges and culverts according to claim 1, characterized in that, The core parameter configurations are compared and verified with on-site monitoring data to obtain a crack control scheme during the construction period, including: Based on the crack control conditions during the construction period, the strain, displacement, and crack width data at the construction site were monitored to obtain on-site monitoring data; The verification and analysis results are obtained by comparing and verifying the on-site monitoring data with the core parameter configuration. Based on the verification analysis results and the core parameter configuration, optimization is performed, and the crack width is limited and optimized based on preset limits to obtain a crack control scheme during the construction period.

7. A crack control system for frame bridges and culverts, characterized in that, include: The acquisition module is used to acquire basic data, which includes the geometric parameters, material parameters, foundation parameters, and construction stage load parameters of the frame bridge and culvert. The processing module is used to perform modeling processing based on the basic data, and to obtain a finite element stress model by performing finite element analysis on the culvert space. The simulation module is used to perform simulation based on the finite element stress model. By simulating different construction conditions and extracting the bending moment and tensile stress distribution of the control section of the web plate under each condition, a set of mechanical performance parameters is obtained. The construction module is used to conduct phased assessments of construction risks based on the set of mechanical performance parameters, and to construct a mathematical model of core parameters by performing parameter analysis on the support structure of the selected construction conditions. The calculation module is used to perform finite element calculations on the target parameters based on the mathematical model of the core parameters. By introducing a temporary cross bracing system and adjusting the cross bracing cross-sectional area, spacing, number of layers and installation elevation, the core parameter configuration of the support system is obtained. The output module is used to compare and verify the core parameter configuration with the on-site monitoring data to obtain a crack control plan during the construction period.

8. A frame bridge / culvert crack control system according to claim 7, characterized in that, The processing module includes: The first processing unit is used to construct a three-dimensional geometric model of the culvert by inputting the structural dimension parameters of the top plate, bottom plate, side walls and web plate based on the geometric parameters of the basic data. The second processing unit is used to perform discrete analysis on the main structural units of the culvert based on the three-dimensional geometric model of the culvert. By selecting the unit type, dividing the mesh, selecting material parameters, and simulating the foundation and boundary conditions, a modeling parameter set is obtained. The third processing unit is used to perform finite element analysis on the culvert space based on the culvert's three-dimensional geometric model and the modeling parameter set, to obtain the finite element stress model of the frame bridge culvert during the construction stage.

9. A frame bridge / culvert crack control system according to claim 7, characterized in that, The simulation module includes: The first simulation unit is used to design construction conditions based on the basic data, establish simulation schemes based on the foundation pit backfilling status, and obtain different construction conditions. The second simulation unit is used to simulate the finite element stress model according to the construction conditions. The simulation results are obtained by simulating the construction conditions of excavation without backfilling, partial backfilling, and full backfilling on both sides of the foundation pit. The third simulation unit is used to extract the bending moment and tensile stress distribution of the web control section under the construction condition based on the simulation results, and obtain a set of mechanical performance parameters.

10. A frame bridge / culvert crack control system according to claim 7, characterized in that, The building module includes: The first building unit is used to conduct a risk assessment based on the set of mechanical performance parameters, compare and analyze the crack width with the preset limit value of crack width, and obtain the crack risk assessment result during the construction period. The second building unit is used to screen the construction conditions based on the construction period crack risk assessment results, and to obtain the construction period crack control conditions by analyzing the stress state and lateral constraint conditions of the web plate. The third building unit is used to perform finite element analysis based on the stiffness, cross-section, and number of layers of the supporting structure under the control conditions, and to build a mathematical model of the core parameters.

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