Active control method for live load bending stress of large-span arch bridge based on influence matrix

Abstract

The invention discloses a large-span arch bridge live load bending stress active control method based on an influence matrix, and relates to the technical field of bridge engineering, and the method comprises the steps: constructing a refined finite element model containing material and geometric nonlinearity; a dead load-long-term effect influence matrix is constructed, and the initial adjustment amount of the closure gap enabling the total bending moment decreasing amplitude to be larger than or equal to 30% is solved; a typical live load working condition and a control target are determined; constructing a live load bending stress control influence matrix, solving the additional adjustment amount, and superposing the initial adjustment amount to obtain the optimal adjustment amount of the closure gap; in the construction stage, the optimal adjustment amount of the closure gap is achieved by adjusting the cable force of the buckle cable, and the actual bending stress of the control section under each typical live load working condition is monitored and verified on site after the bridge is formed. According to the method, full-load collaborative optimization can be achieved, the consumption of main arch materials is reduced, the method is suitable for multiple types of arch bridges, and control precision, engineering practicability and economical efficiency are considered.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering technology, and more specifically to an active control method for live load bending stress of long-span arch bridges based on an influence matrix. Background Technology

[0002] With the advancement of transportation infrastructure construction in the western mountainous areas and across river canyons, long-span arch bridges have become a core bridge type for traversing complex terrains due to their reasonable stress distribution, high stiffness, and excellent economy. While the live load on these bridges may not constitute a large proportion of the total bridge load when bearing highway and railway traffic loads, it can induce significant bending stress in key sections of the arch ribs (arch crown, arch foot, and L / 4 section). This leads to stress concentration and uneven stress distribution across the sections, which can exacerbate structural fatigue damage over long-term exposure, reduce the bridge's service life, and even threaten operational safety. Therefore, precise control of the live load bending stress in long-span arch bridges has become a core requirement for ensuring both structural safety and economy.

[0003] While some progress has been made in the technical means of controlling the internal forces of long-span arch bridges, significant limitations remain in the active control of live load bending stress, making it difficult to meet the needs of efficient and precise design and operation of long-span arch bridges. Specific shortcomings are as follows: (1) Existing methods for optimizing the internal forces of arch bridges mostly focus on optimizing the arch axis under dead load or adjusting the temporary internal forces during the construction phase, ignoring the dynamic and random nature of live loads and their coupling effect on bending stress. (2) Although the traditional influence matrix method has been applied to the adjustment of internal forces in arch bridges, the existing technology has not applied its system to the active control of live load bending stress. (3) At present, stress control of long-span arch bridges mostly relies on passive monitoring technology (such as fiber optic grating sensors and resistance strain gauge monitoring) and post-event parameter correction, which cannot actively cope with stress fluctuations caused by changes in live load; (4) The distribution of live load bending stress in long-span arch bridges has significant spatial differences. The stress peaks at the control sections such as the arch crown, arch foot, and L / 4 section are often asynchronous, and existing methods are difficult to achieve coordinated optimization of stress at multiple sections. (5) Existing live load stress control methods mostly remain at the theoretical analysis level, without clearly defining the control variables and implementation paths that can be operated during the construction stage, resulting in a disconnect between design objectives and construction effects.

[0004] Therefore, in the current field of live load bending stress control for long-span arch bridges, there is an urgent need for a technical method that can accurately correlate live load characteristics with structural control parameters, has active adaptation capabilities, can achieve multi-section collaborative optimization, and connects with construction implementation, in order to solve the problems of insufficient targeting, lack of active control, poor coordination, and weak implementation of existing technologies, and ensure the structural safety and long-term durability of long-span arch bridges during the operation phase. Summary of the Invention

[0005] In view of this, the present invention provides an active control method for live load bending stress of long-span arch bridges based on influence matrix, which solves the problems existing in the background technology.

[0006] To achieve the above objectives, the present invention provides the following technical solution: An active control method for live load bending stress of a long-span arch bridge based on an influence matrix includes the following steps: S1. Based on the design parameters of the long-span arch bridge, establish a refined finite element model that can simulate the mechanical behavior of the main arch rib and construction cable and take into account the nonlinear and geometrical effects of materials. S2. Based on the refined finite element model, construct the influence matrix of dead load-long-term effect, and solve for the initial adjustment amount of the closure joint to make the total bending moment reduction of dead load-long-term effect reach the preset target. S3. Determine typical live load conditions according to the operational needs of arch bridges, and simultaneously set control targets for balanced distribution of live load bending stress at each control section and ensuring that the peak value does not exceed the limit. S4. Simulate various typical live load conditions in the refined finite element model to calculate the live load reference stress, construct the live load bending stress control influence matrix, solve for the additional adjustment amount of the closure joint that satisfies the control target and superimpose it with the initial adjustment amount of the closure joint to obtain the optimal adjustment amount of the closure joint. S5. During the construction phase, the cable tension of the closure section is adjusted to achieve the optimal adjustment amount. After the bridge is completed, the actual bending stress of the control section under each typical live load condition is monitored on site to verify whether the control target is met. If not, the process is returned to S4 to correct the additional adjustment amount and then reimplemented.

[0007] Optionally, in S1, the design parameters of the long-span arch bridge include the span, rise, arch rib section parameters, and load distribution on the arch. The arch rib section parameters are the width, height, web thickness, and top and bottom plate thickness of the box section. If the long-span arch bridge is a stiffened reinforced concrete arch bridge, the refined finite element model uses solid elements to simulate the synergistic effect of the steel tube stiffened frame and the outer concrete. The main arch rib is simulated using variable cross-section beam elements, and the construction tie cable is simulated using truss elements. Material nonlinearity is represented by the concrete plastic damage model or the ideal elastic-plastic model of steel.

[0008] Optionally, in S2, the method for constructing the influence matrix of dead load-long-term effects is as follows: taking the horizontal displacement and rotation angle of the closure joint as control variables, applying unit horizontal displacement and unit rotation angle respectively in the refined finite element model, calculating the change in bending moment of each control section under unit control variables, and forming the influence matrix; among which, the long-term effects include concrete shrinkage and creep, and the preset target is that the total bending moment of dead load-long-term effects is ≥30% lower than the initial dead load bending moment.

[0009] Optionally, in S3, typical live load conditions include full-span live load, half-span live load, and off-center load.

[0010] Optionally, in S3, the control objective is specifically: the peak deviation of the live load bending stress at each control section is ≤10%, and the peak value of the live load bending stress is ≤10% of the corresponding material design strength; wherein, the material design strength of the concrete arch rib is taken according to the strength grade, and the material design strength of the steel arch rib is taken according to the steel grade.

[0011] Optionally, in S4, the construction of the influence matrix for the control of live load bending stress needs to consider the dynamic effect of the live load. Specifically, the influence line is applied to the moving live load to calculate the maximum live load bending stress and the corresponding influence coefficient of each control section. Furthermore, the influence matrix needs to be cross-validated by at least two finite element software programs. If the deviation of the influence coefficients of different software programs is ≤5%, the influence matrix is ​​deemed valid.

[0012] Optionally, in S4, the additional adjustment amount at the closure joint is solved by linear programming or least squares method. The solution constraint is that the live load bending stress of each control section meets the control objective of S3. The superposition logic is: the final horizontal displacement of the closure joint = the initial horizontal displacement of the closure joint + the additional horizontal displacement of the closure joint, and the final rotation angle of the closure joint = the initial rotation angle of the closure joint + the additional rotation angle of the closure joint.

[0013] Optionally, in S5, the adjustment of the cable tension needs to rely on the influence relationship between the cable and the closure joint displacement. Based on the influence coefficient of the cable on the closure joint displacement, the tension or relaxation of each cable is calculated. During the adjustment process, the arch rib alignment needs to be monitored simultaneously. The vertical and horizontal displacements of the 8 points of the arch rib are measured using a total station. If the alignment deviation exceeds 1 / 3000 of the span, the adjustment is paused and the optimal adjustment amount of the closure joint is corrected.

[0014] Optionally, in S5, on-site monitoring uses fiber optic grating sensors or resistance strain gauges to collect stress data, with a monitoring duration of no less than 72 hours and covering the peak live load period; the verification standard is: the deviation between the actual bending stress and the simulated value of the refined finite element model is ≤8%, and the control target of S3 is met.

[0015] Optionally, a temperature effect compensation step is also included, specifically: when solving for the additional adjustment amount at the closure joint in S4, the difference between the closure temperature and the design reference temperature is calculated, and the temperature displacement and temperature rotation angle of the closure joint caused by temperature are obtained through a refined finite element model. These are then incorporated as the additional temperature adjustment amount into the optimal adjustment amount of the closure joint, i.e.: final horizontal displacement of the closure joint = initial horizontal displacement of the closure joint + additional horizontal displacement of the closure joint + temperature horizontal displacement, final rotation angle of the closure joint = initial rotation angle of the closure joint + additional rotation angle of the closure joint + temperature rotation angle.

[0016] As can be seen from the above technical solution, compared with the prior art, the present invention discloses an active control method for live load bending stress of long-span arch bridges based on the influence matrix, which has the following beneficial effects: (1) Technical precision: This invention breaks through the limitations of traditional single load control and can achieve the overall system synergistic optimization of "dead load-long-term effect-live load"; the peak deviation of live load stress is ≤10%, upgrading from passive monitoring to active precision control, and the control precision is improved by more than 50% compared with traditional methods; (2) Engineering practicality: This invention is suitable for the mainstream process of "cantilever assembly + cable adjustment" for long-span arch bridges. By adjusting the cable tension, the target can be directly controlled, forming a closed loop of "design-implementation-72h live load peak monitoring" to ensure traceability of the effect; (3) Economic rationality: This invention can reduce the redundant design of the arch rib (reduce the amount of main arch ring material by more than 20%), reduce live load fatigue damage, extend the bridge life by 5-10 years, and reduce the total life cycle operation and maintenance cost by more than 10%. (4) Safety and versatility: The peak value of the live load stress of the present invention does not exceed 10% of the material design strength, which can effectively reduce the bending effect, thereby making the stress distribution of the arch rib more uniform and significantly improving the material utilization rate; it is suitable for various types of arch bridges such as steel-concrete composite and rigid frame with spans of 400-1000m, without the need for specific adjustments. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 A flowchart of the active control method for live load bending stress of a long-span arch bridge based on an influence matrix provided by the present invention; Figure 2 A flowchart of the constant load and long-term effect bending moment amplitude adjustment method based on the influence matrix provided by the present invention; Figure 3 This is a schematic diagram of the bending moment distribution of the arch ring under full-span live load provided by the present invention; Figure 4 This is a schematic diagram of the stress distribution of the arch ring under full-span live load provided by the present invention. Detailed Implementation

[0019] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention discloses an active control method for live load bending stress of a long-span arch bridge based on an influence matrix, such as... Figure 1 As shown, it includes the following steps: S1. Based on the design parameters of the long-span arch bridge, establish a refined finite element model that can simulate the mechanical behavior of the main arch rib and construction cable and take into account the nonlinear and geometrical effects of materials. S2. Based on the refined finite element model, construct the influence matrix of dead load-long-term effect, and solve for the initial adjustment amount of the closure joint to make the total bending moment reduction of dead load-long-term effect reach the preset target. S3. Determine typical live load conditions according to the operational needs of arch bridges, and simultaneously set control targets for balanced distribution of live load bending stress at each control section and ensuring that the peak value does not exceed the limit. S4. Simulate various typical live load conditions in the refined finite element model to calculate the live load reference stress, construct the live load bending stress control influence matrix, solve for the additional adjustment amount of the closure joint that satisfies the control target and superimpose it with the initial adjustment amount of the closure joint to obtain the optimal adjustment amount of the closure joint. S5. During the construction phase, the cable tension of the closure section is adjusted to achieve the optimal adjustment amount. After the bridge is completed, the actual bending stress of the control section under each typical live load condition is monitored on site to verify whether the control target is met. If not, the process is returned to S4 to correct the additional adjustment amount and then reimplemented.

[0021] Furthermore, in S1 of this embodiment, the design parameters of the long-span arch bridge include span, rise, arch rib section parameters, and load distribution on the arch. The arch rib section parameters are the width, height, web thickness, and top and bottom plate thickness of the box section. If the long-span arch bridge is a stiffened reinforced concrete arch bridge, the refined finite element model uses solid elements to simulate the synergistic effect of the steel tube stiffened frame and the outer concrete. The main arch rib is simulated using variable cross-section beam elements, the construction tie cable is simulated using truss elements, and the material nonlinearity is reflected by the concrete plastic damage model or the ideal elastic-plastic model of steel.

[0022] Furthermore, in S2 of this embodiment, the method for constructing the influence matrix of dead load-long-term effect is as follows: taking the horizontal displacement and rotation angle of the closure joint as control variables, applying unit horizontal displacement and unit rotation angle respectively in the refined finite element model, calculating the change in bending moment of each control section under unit control variables, and forming the influence matrix; wherein, the long-term effect includes concrete shrinkage and creep, and the preset target is that the total bending moment of dead load-long-term effect is ≥30% lower than the initial dead load bending moment.

[0023] Specifically, S2 adopts the "moment adjustment method based on the influence matrix of dead load and long-term effects", and the steps are as follows (e.g. Figure 2 (as shown) 1) Calculate the reference internal forces: Using the refined finite element model of S1, obtain the initial bending moments of each control section of the arch rib (arch crown, arch foot, L / 4 section, 3L / 4 section) under dead load. and the additional bending moment of the corresponding section under the long-term effects of shrinkage and creep. , Among them, shrinkage strain is calculated according to Appendix C of the "Design Specification for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts" (JTG 3362-2018), the calculation period for creep effect is not less than 10 years, and the impact of subsequent closure adjustment on internal force redistribution must be taken into account. 2) Constructing the influence matrix: Using the horizontal displacement and rotation angle of the closure joint as control variables, apply unit horizontal displacement (e.g., 1 mm) and unit rotation angle (e.g., 1 × 10⁻⁶) to the refined finite element model. -4 (rad), calculate the change in bending moment at each control section under unit control variable, form a 2×4 order dead load-long-term effect influence matrix, and clarify the quantitative relationship between control variable and bending moment; 3) Solving for the initial adjustment: With the goal of reducing the total bending moment of "dead load-long-term effect" by ≥30% compared with the initial dead load bending moment, a system of linear equations is established, and the initial horizontal displacement and initial rotation angle of the closure joint are solved by the least squares method. 4) Iterative verification and correction: Substitute the initial adjustment amount into the model, recalculate the total bending moment, and if the reduction does not meet the target, update the target and repeat the above steps until the requirements are met.

[0024] Furthermore, in S3 of this embodiment, typical live load conditions include full-span live load, half-span live load, and off-center load.

[0025] Furthermore, in S3 of this embodiment, the control objective is specifically: the peak deviation of the live load bending stress of each control section is ≤10%, and the peak value of the live load bending stress is ≤10% of the corresponding material design strength; wherein, the material design strength of the concrete arch rib is taken according to the strength grade, and the material design strength of the steel arch rib is taken according to the steel grade.

[0026] Furthermore, in S4 of this embodiment, the construction of the influence matrix for controlling the live load bending stress needs to consider the dynamic effect of the live load. Specifically, the influence line is applied to the moving live load to calculate the maximum live load bending stress and the corresponding influence coefficient of each control section. In addition, the influence matrix needs to be cross-validated by at least two finite element software programs. If the deviation of the influence coefficients of different software programs is ≤5%, the influence matrix is ​​deemed to be valid.

[0027] Furthermore, in S4 of this embodiment, the additional adjustment amount at the closure joint is solved by linear programming or least squares method. The solution constraint is that the live load bending stress of each control section meets the control objective of S3. The superposition logic is: the final horizontal displacement of the closure joint = the initial horizontal displacement of the closure joint + the additional horizontal displacement of the closure joint, and the final rotation angle of the closure joint = the initial rotation angle of the closure joint + the additional rotation angle of the closure joint.

[0028] Specifically, S4 adopts the "live load bending moment adjustment method based on influence matrix", and the steps are as follows: 1) Calculate the live load reference stress: Substitute the initial adjustment amount of the closure joint obtained from S2 into the model to simulate typical working conditions such as full-span live load, half-span full-span live load, and eccentric load, and obtain the reference value of live load bending stress for each control section; For moving live loads (such as highway convoys and railway trains), influence line loading is used to ensure that the maximum stress response is captured. 2) Constructing the live load bending stress control influence matrix: Continuing the control variables of S2 (horizontal displacement and rotation at the closure point), unit variables are applied to the model to calculate the stress change at each control section under each live load condition, forming the live load bending stress control influence matrix; this matrix is ​​cross-validated using Abaqus, Midas Civil, etc., ensuring that the influence coefficient deviation is ≤5%; 3) Solve for additional adjustment: With the constraint that "the peak deviation of the live load bending stress of each control section is ≤10% and the peak value of the live load bending stress is ≤10% of the corresponding material design strength", solve for the additional horizontal displacement and additional rotation at the closure joint by linear programming or least squares method. 4) Superimpose to obtain the optimal adjustment amount: According to the logic of "final horizontal displacement = initial horizontal displacement + additional horizontal displacement, final rotation angle = initial rotation angle + additional rotation angle", the optimal adjustment amount of the closure section is obtained by superimposing.

[0029] In this embodiment, the typical live load condition is taken as "full span live load". The load values ​​transmitted by the upper columns of the arch ring are close, and the bending distribution of the arch ring is approximately the same as that of a uniformly distributed load. Because the arch axis used in long-span arch bridges has a quarter-point height... All these values ​​are higher than the parabola, therefore, under uniformly distributed load, the arch ring bending moment of a long-span arch bridge will pass through the zero moment point twice at half span, with positive bending moment peaks at the arch crown and arch foot, and negative bending moment peaks at L / 4. Figure 3 As shown; similarly, stress peaks in the arch ring will appear at the crown, arch foot, and L / 4 position, as shown. Figure 4 As shown.

[0030] After the cables are removed and the arch is formed, the bending stress at the top of the arch is The arch foot bending stress is The bending stress at L / 4 is It is necessary to determine the length of the arch closure opening. dx With corner ryThe adjusted stresses are respectively , Establish the relative changes in bending stress at the crown and L / 4 point after the cable-stayed arch is constructed. The relative change in bending stress at the arch foot and L / 4 Length of the closure opening of the arch before the cable-stayed arch is dismantled dx With corner ry The relationship.

[0031]

[0032] in, The influence matrix can be represented as:

[0033] In the formula: , These represent the arch crown bending moment values ​​after the unit horizontal displacement and rotation at the closure point are removed and the cables are untied to form an arch, respectively. , These represent the arch foot bending moment values ​​after the unit horizontal displacement and the angle of rotation are set at the closure point to form the arch. The coefficient matrix can be calculated using the finite element method, and the horizontal displacement and rotation target at the closure point can be solved using the following formula:

[0034] Furthermore, in S5 of this embodiment, the adjustment of the cable tension needs to rely on the influence relationship between the cable and the closure gap displacement. Based on the influence coefficient of the cable on the closure gap displacement, the tension or relaxation amount of each cable is calculated. During the adjustment process, the arch rib alignment needs to be monitored simultaneously. The vertical and horizontal displacements of the 8 points of the arch rib are measured using a total station. If the alignment deviation exceeds 1 / 3000 of the span, the adjustment is paused and the optimal adjustment amount of the closure gap is corrected.

[0035] Furthermore, in S5 of this embodiment, stress data is collected by fiber optic grating sensors or resistance strain gauges during on-site monitoring. The monitoring duration is not less than 72 hours and covers the peak period of live load. The verification standard is: the deviation between the actual bending stress and the simulated value of the refined finite element model is ≤8%, and the control target of S3 is met.

[0036] Furthermore, this embodiment also includes a temperature effect compensation step, specifically: when solving for the additional adjustment amount at the closure joint in S4, the difference between the closure temperature and the design reference temperature is calculated, and the temperature displacement and temperature rotation angle of the closure joint caused by temperature are obtained through a refined finite element model. These are then incorporated as the additional temperature adjustment amount into the optimal adjustment amount of the closure joint, i.e.: the final horizontal displacement of the closure joint = the initial horizontal displacement of the closure joint + the additional horizontal displacement of the closure joint + the temperature horizontal displacement, and the final rotation angle of the closure joint = the initial rotation angle of the closure joint + the additional rotation angle of the closure joint + the temperature rotation angle.

[0037] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0038] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for active control of live load bending stress in a long-span arch bridge based on an influence matrix, characterized in that, Includes the following steps: S1. Based on the design parameters of the long-span arch bridge, establish a refined finite element model that can simulate the mechanical behavior of the main arch rib and construction cable and take into account the nonlinear and geometrical effects of materials. S2. Based on the refined finite element model, construct the influence matrix of dead load-long-term effect, and solve for the initial adjustment amount of the closure joint to make the total bending moment reduction of dead load-long-term effect reach the preset target. S3. Determine typical live load conditions according to the operational needs of arch bridges, and simultaneously set control targets for balanced distribution of live load bending stress at each control section and ensuring that the peak value does not exceed the limit. S4. Simulate various typical live load conditions in the refined finite element model to calculate the live load reference stress, construct the live load bending stress control influence matrix, solve for the additional adjustment amount of the closure joint that satisfies the control target and superimpose it with the initial adjustment amount of the closure joint to obtain the optimal adjustment amount of the closure joint. S5. During the construction phase, the cable tension of the closure section is adjusted to achieve the optimal adjustment amount. After the bridge is completed, the actual bending stress of the control section under each typical live load condition is monitored on site to verify whether the control target is met. If not, the process is returned to S4 to correct the additional adjustment amount and then reimplemented.

2. The active control method for live load bending stress of a long-span arch bridge based on an influence matrix according to claim 1, characterized in that, In S1, the design parameters of the long-span arch bridge include the span, rise, arch rib section parameters, and load distribution on the arch. The arch rib section parameters are the width, height, web thickness, and top and bottom plate thickness of the box section. If the long-span arch bridge is a stiffened reinforced concrete arch bridge, the refined finite element model uses solid elements to simulate the synergistic effect of the steel tube stiffened frame and the outer concrete. The main arch rib is simulated using variable cross-section beam elements, and the construction tie cable is simulated using truss elements. Material nonlinearity is reflected by the concrete plastic damage model or the ideal elastic-plastic model of steel.

3. The active control method for live load bending stress of a long-span arch bridge based on an influence matrix according to claim 1, characterized in that, In S2, the method for constructing the influence matrix of dead load-long-term effects is as follows: taking the horizontal displacement and rotation angle of the closure joint as control variables, applying unit horizontal displacement and unit rotation angle respectively in the refined finite element model, calculating the change in bending moment of each control section under unit control variables, and forming the influence matrix; among which, the long-term effects include concrete shrinkage and creep, and the preset target is that the total bending moment of dead load-long-term effects is ≥30% lower than the initial dead load bending moment.

4. The active control method for live load bending stress of a long-span arch bridge based on an influence matrix according to claim 1, characterized in that, In S3, typical live load conditions include full-span live load, half-span live load, and eccentric load.

5. The active control method for live load bending stress of a long-span arch bridge based on an influence matrix according to claim 1, characterized in that, In S3, the specific control objectives are: the peak deviation of the live load bending stress at each control section is ≤10%, and the peak value of the live load bending stress is ≤10% of the corresponding material design strength; among which, the material design strength of the concrete arch rib is taken according to the strength grade, and the material design strength of the steel arch rib is taken according to the steel grade.

6. The active control method for live load bending stress of a long-span arch bridge based on an influence matrix according to claim 1, characterized in that, In S4, the construction of the influence matrix for the control of live load bending stress needs to consider the dynamic effect of live load. Specifically, the influence line is applied to the moving live load to calculate the maximum live load bending stress and the corresponding influence coefficient of each control section. Furthermore, the influence matrix needs to be cross-validated by at least two finite element software programs. If the deviation of the influence coefficients of different software programs is ≤5%, the influence matrix is ​​deemed valid.

7. The active control method for live load bending stress of a long-span arch bridge based on an influence matrix according to claim 1, characterized in that, In S4, the additional adjustment amount at the closure joint is solved by linear programming or least squares method. The solution constraint is that the live load bending stress of each control section meets the control objective of S3. The superposition logic is: the final horizontal displacement of the closure joint = the initial horizontal displacement of the closure joint + the additional horizontal displacement of the closure joint, and the final rotation angle of the closure joint = the initial rotation angle of the closure joint + the additional rotation angle of the closure joint.

8. The active control method for live load bending stress of a long-span arch bridge based on an influence matrix according to claim 1, characterized in that, In S5, the adjustment of the cable tension needs to rely on the influence relationship between the cable tension and the closure gap displacement. Based on the influence coefficient of the cable tension on the closure gap displacement, the tension or relaxation amount of each cable tension is calculated. During the adjustment process, the arch rib alignment needs to be monitored simultaneously. The vertical and horizontal displacements of the 8 points of the arch rib are measured using a total station. If the alignment deviation exceeds 1 / 3000 of the span, the adjustment is paused and the optimal adjustment amount of the closure gap is corrected.

9. The active control method for live load bending stress of a long-span arch bridge based on an influence matrix according to claim 1, characterized in that, In S5, on-site monitoring uses fiber optic grating sensors or resistance strain gauges to collect stress data, with a monitoring duration of no less than 72 hours and covering the peak live load period; the verification standard is: the deviation between the actual bending stress and the simulated value of the refined finite element model is ≤8%, and the control target of S3 is met.

10. A method for active control of live load bending stress in a long-span arch bridge based on an influence matrix, as described in any one of claims 1-9, characterized in that, It also includes a temperature effect compensation step, specifically: when solving for the additional adjustment amount at the closure joint in S4, the difference between the closure temperature and the design reference temperature is calculated. The temperature displacement and temperature rotation angle of the closure joint caused by temperature are obtained through a refined finite element model, and these are incorporated into the optimal adjustment amount of the closure joint as additional temperature adjustment amount. That is: the final horizontal displacement of the closure joint = the initial horizontal displacement of the closure joint + the additional horizontal displacement of the closure joint + the temperature horizontal displacement, and the final rotation angle of the closure joint = the initial rotation angle of the closure joint + the additional rotation angle of the closure joint + the temperature rotation angle.

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