Large-span bridge construction monitoring method

Abstract

The invention discloses a long-span bridge construction monitoring method which is applied to the technical field of construction control. Comprising the steps of obtaining sensor monitoring data of each bridge section in a current construction stage; preprocessing the monitoring data of the sensor; calculating the structural displacement and stress state of each bridge section under the action of self weight, prestress, concrete shrinkage and creep and temperature change according to the preprocessed data to obtain the structural displacement and stress state of each construction stage; according to the calculated structural displacement and stress state of each construction stage, determining the formwork erection elevation of the bridge structure of each construction stage through backward analysis; and correcting the difference value between the formwork erecting elevation and the predicted value, so as to monitor the construction of each bridge section. According to the construction monitoring method, internal force and displacement of each stage can be prevented from deviating from the design value along with the change of the concrete pouring process, the safety of the structure in the construction process is improved, the construction safety and quality are guaranteed, and the construction finished bridge state meets the design requirement.

Description

Technical Field

[0001] This invention relates to the field of construction control technology, and more specifically to a method for monitoring the construction of long-span bridges. Background Technology

[0002] my country is currently making great strides in expanding its transportation network, and bridges are an important component of this network. Whether it's urban bridges, highway bridges, or high-speed railway bridges, continuous beam bridges are widely used due to their inherent advantages. During the construction of continuous beam bridges using the cantilever construction method, the internal forces and alignment of the structure change with the construction sequence. To ensure smooth bridge construction and a smooth, linear structure with reasonable stress distribution after completion, construction monitoring is essential.

[0003] In the construction of long-span bridges, especially for steel-concrete composite structures assembled with minimal supports (beams first, arches later), strict requirements are placed on the arch axis shape, box girder internal forces, and suspender tension. Changes in the coordinates of each node affect the distribution of internal forces. If the bridge alignment deviates from the design values, the internal forces will inevitably deviate from the design values. Furthermore, the stiffness of the structural components varies significantly, and the relationship between force and deformation is highly complex due to factors such as suspender forces, temperature changes, wind and sunlight, and temporary construction loads. While various calculation methods can be used to calculate the suspender forces and corresponding beam and arch rib deformations at each construction stage, the actual deformation of the structure may not meet the expected results when constructed based on the theoretically calculated suspender forces and alignment. This is mainly because the calculation parameters used in the design, such as the material's elastic modulus, component weight, temperature changes during construction, and temporary construction load conditions, are not entirely consistent with those observed in actual engineering. The deviation between theory and practice in the construction of long-span bridges is cumulative. If it is not controlled and adjusted in a timely and effective manner, the structural alignment will eventually deviate significantly from the design target, affecting the internal force state after the bridge is completed, and reducing the structural safety, construction safety and quality during the construction process.

[0004] Therefore, proposing a construction monitoring method for long-span bridges to address the difficulties of existing technologies is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a method for monitoring the construction of long-span bridges to solve the technical problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for monitoring the construction of long-span bridges includes the following steps: Acquire sensor monitoring data for each bridge section during the current construction phase; Preprocessing is performed on the sensor monitoring data to obtain preprocessed data; Based on the obtained preprocessed data, the structural displacement and stress state of each bridge section under the action of self-weight, prestress, concrete shrinkage and creep and temperature change are calculated to obtain the structural displacement and stress state of each construction stage. Based on the calculated structural displacements and stress states at each construction stage, the formwork elevation of the bridge structure at each construction stage is determined through backward analysis. By comparing the obtained formwork elevation of the bridge structure at each construction stage with the predicted value, the difference between the formwork elevation and the predicted value is corrected, thereby monitoring the construction of each bridge section.

[0007] Optionally, the monitoring data for the above methods may include arch rib deformation, main beam deformation, and hanger cable tension.

[0008] Optionally, the sensor monitoring data described above can be collected by multiple sensors installed on each bridge section.

[0009] The above methods may use sensors including, but not limited to, strain gauge force sensors, fiber optic sensors, piezoelectric sensors, and steel wire sensors.

[0010] The above method, optionally, involves a backward analysis: assuming that the internal force distribution of the structure at the time of bridge completion meets the results of the forward analysis, and the axis meets the design alignment requirements, the structure is dismantled in reverse order of the forward analysis. The impact of each dismantling of a construction stage on the remaining structure is analyzed, and the structural displacement and internal force state obtained in each stage analysis are the structural construction state of each stage.

[0011] Optionally, the above method, before determining the formwork elevation of the bridge structure at each construction stage through backward analysis, may also include: The actual deformation value of the hanging basket is determined based on the pre-loading test of the hanging basket. The pre-camber of the bridge structure is determined based on the deformation value of the hanging basket and the backward analysis.

[0012] Optionally, the specific details of determining the deformation value of the hanging basket based on the pre-loading test are as follows: The preloading test uses a staged loading method, and the actual deformation value of the hanging basket is calculated using a formula:

[0013] in, For pouring the first n The elastic deformation value of the hanging basket when the number of blocks is specified; , , For pouring the first n After the concrete block n ,n -1、 n Displacement at the front end of bridge section -2; , For the first n , n -1 is the length of bridge section.

[0014] Optionally, after determining the formwork elevation of the bridge structure at each construction stage through backward analysis, the above method may also include: Stress measuring points were set up at multiple control sections of the bridge to monitor stress changes and stress distribution at multiple control sections during construction. The safety of the completed bridge is determined based on the stress changes and distribution at multiple control sections and the calculated formwork elevation.

[0015] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a method for monitoring the construction of long-span bridges, the beneficial effects of which are: The construction monitoring method provided by this invention can prevent the internal forces and displacements at each stage from deviating from the design values ​​as the concrete pouring process changes, thereby improving the structural safety during construction, ensuring construction safety and quality, and ultimately ensuring that the completed bridge meets the design requirements. Attached Figure Description

[0016] 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.

[0017] Figure 1 A flowchart of a construction monitoring method for long-span bridges provided by the present invention; Figure 2 The pre-camber diagram of the bridge structure provided by this invention; Among them, 1-design elevation, 2-formwork elevation. Detailed Implementation

[0018] 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.

[0019] See Figure 1As shown, this invention discloses a method for monitoring the construction of long-span bridges, comprising the following steps: Acquire sensor monitoring data for each bridge section during the current construction phase; Preprocess the sensor monitoring data to obtain preprocessed data; Based on the obtained preprocessed data, the structural displacement and stress state of each bridge section under the action of self-weight, prestress, concrete shrinkage and creep and temperature change are calculated to obtain the structural displacement and stress state of each construction stage. Based on the calculated structural displacements and stress states at each construction stage, the formwork elevation of the bridge structure at each construction stage is determined through backward analysis. By comparing the obtained formwork elevation of the bridge structure at each construction stage with the predicted value, the difference between the formwork elevation and the predicted value is corrected, thereby monitoring the construction of each bridge section.

[0020] Furthermore, the monitoring data includes arch rib deformation, main beam deformation, and suspender cable tension.

[0021] Furthermore, the sensor monitoring data is collected by multiple sensors installed on each bridge section.

[0022] Furthermore, sensors include, but are not limited to, strain gauge force sensors, fiber optic sensors, piezoelectric sensors, and steel wire sensors.

[0023] Specifically, steel wire sensors have advantages such as good stability and strain accumulation function, strong anti-interference ability, and convenient data acquisition. Steel wire sensors are used to obtain sensor monitoring data of each bridge section in the current construction stage.

[0024] Furthermore, the backward analysis specifically involves: assuming that the internal force distribution of the structure at the time of bridge completion meets the results of the forward analysis, and the axis meets the design alignment requirements, the structure is dismantled in reverse order of the forward analysis. The impact of each dismantling of a construction stage on the remaining structure is analyzed, and the structural displacement and internal force state obtained in each stage analysis are the structural construction state of each stage.

[0025] Specifically, the structural construction state refers to the intended position and stress state of the structure at each stage of construction. The ideal construction state at each stage will control the final shape and stress characteristics of the entire bridge. Construction control will adjust the calculations based on the deviation between the actual state and the ideal state at each stage, analyze the causes of errors, and accurately estimate the beam deflection in the next stage.

[0026] Furthermore, before determining the formwork elevation of the bridge structure at each construction stage through backward analysis, the following steps are also included: The actual deformation value of the hanging basket is determined based on the pre-loading test of the hanging basket. The pre-camber of the bridge structure is determined based on the deformation value of the hanging basket and the backward analysis.

[0027] For details, see Figure 2 As shown, the pre-camber diagram illustrates the design elevation 1 and formwork elevation 2 within the bridge structure. The formwork elevation is not equal to the designed final bridge elevation; a certain pre-camber needs to be calculated to compensate for various deformations (vertical deflections) that occur during construction. The calculation formula is as follows:

[0028] in, for i Stage-by-stage model elevation, for i Stage design elevation, The bridge section's self-weight is due to the construction weight of this phase and subsequent phases. i The total deflection generated in each stage For the prestressing in the tensioning stage and subsequent construction stages i Deflection caused by the stage For concrete shrinkage and creep i Deflection caused by the stage For temporary construction loads i Deflection caused by the stage To take the load in i 50% of the deflection caused by the stage. This represents the actual elastic deformation value of the formwork; the actual deformation value of the formwork is determined based on the formwork loading test and taken into account during construction. , , , , The precamber of each bridge segment can be calculated based on the above calculation formula and monitoring analysis, which has already taken into account in the forward and backward analysis calculations.

[0029] Furthermore, the specific details for determining the deformation value of the hanging basket based on the pre-loading test are as follows: The preloading test uses a staged loading method, and the actual deformation value of the hanging basket is calculated using a formula:

[0030] in, For pouring the first n The elastic deformation value of the hanging basket when the number of blocks is specified; , , For pouring the first n After the concrete block n , n -1、 nDisplacement at the front end of bridge section -2; , For the first n , n -1 is the length of bridge section.

[0031] Furthermore, after determining the formwork elevation of the bridge structure at each construction stage through backward analysis, the process also includes: Stress measuring points were set up at multiple control sections of the bridge to monitor stress changes and stress distribution at multiple control sections during construction. The safety of the completed bridge is determined based on the stress changes and distribution at multiple control sections and the calculated formwork elevation.

[0032] Specifically, through monitoring during the construction process, the stress and strain of each component of the bridge structure can be monitored in real time.

[0033] In a specific embodiment, there are many basic parameters affecting the structural alignment and internal forces, and the main parameters that need to be measured are: The elastic modulus of concrete is determined in the early structural calculations according to the specifications, and then determined based on the test results during construction. The elastic modulus of concrete should be tested by taking samples on site and measuring the elastic modulus values ​​of concrete at 4 days, 8 days, and 26 days of age, so as to provide data for the correction of the bridge pre-camber.

[0034] The elastic modulus of prestressed steel strand shall be adopted according to the results of on-site sampling tests. The dead load is based on the dimensions provided in the design drawings, and is modified as necessary according to parameters such as concrete unit weight collected at the construction site, taking into account the structural self-weight and temporary loads, as well as the influence of beam slope. The shrinkage and creep coefficients of concrete are adopted in accordance with the specifications, and the calculation takes into account the local temperature difference effect of the structure and the shrinkage and creep effect of the concrete at the actual loading age. The coefficient of thermal expansion of the material shall be taken according to the specification. Temporary construction loads will be counted on-site to minimize the stockpiling of materials. Unused materials for this phase will be stored near block #0. The friction coefficient of the prestressed duct is determined based on on-site friction tests.

[0035] Before construction, it is necessary to have a prior understanding of the stress state and alignment of the bridge at each construction stage. Therefore, structural calculations are required. In addition to meeting the basic requirements of conforming to the actual construction methods, the construction control calculations for this bridge must also consider many other related factors.

[0036] 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.

[0037] 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 monitoring the construction of long-span bridges, characterized in that, Includes the following steps: Acquire sensor monitoring data for each bridge section during the current construction phase; Preprocessing is performed on the sensor monitoring data to obtain preprocessed data; Based on the obtained preprocessed data, the structural displacement and stress state of each bridge section under the action of self-weight, prestress, concrete shrinkage and creep and temperature change are calculated to obtain the structural displacement and stress state of each construction stage. Based on the calculated structural displacements and stress states at each construction stage, the formwork elevation of the bridge structure at each construction stage is determined through backward analysis. By comparing the obtained formwork elevation of the bridge structure at each construction stage with the predicted value, the difference between the formwork elevation and the predicted value is corrected, thereby monitoring the construction of each bridge section.

2. The construction monitoring method for long-span bridges according to claim 1, characterized in that, The monitoring data includes arch rib deformation, main beam deformation, and hanger cable tension.

3. The construction monitoring method for long-span bridges according to claim 1, characterized in that, The sensor monitoring data is collected by multiple sensors installed on each section of the bridge.

4. The construction monitoring method for long-span bridges according to claim 3, characterized in that, Sensors include, but are not limited to, strain gauge force sensors, fiber optic sensors, piezoelectric sensors, and steel wire sensors.

5. The construction monitoring method for long-span bridges according to claim 1, characterized in that, The reverse analysis is as follows: assuming that the internal force distribution of the structure at the time of bridge completion meets the results of the forward analysis and the axis meets the design alignment requirements, the structure is dismantled in reverse process of the forward analysis. The impact of each dismantling of a construction stage on the remaining structure is analyzed. The structural displacement and internal force state obtained in each stage analysis are the structural construction state of each stage.

6. The construction monitoring method for long-span bridges according to claim 1, characterized in that, Before determining the formwork elevation of the bridge structure at each construction stage through backward analysis, the following steps are also included: The actual deformation value of the hanging basket is determined based on the pre-loading test of the hanging basket. The pre-camber of the bridge structure is determined based on the deformation value of the hanging basket and the backward analysis.

7. The construction monitoring method for long-span bridges according to claim 6, characterized in that, The specific details for determining the deformation value of the hanging basket based on the preloading test are as follows: The preloading test uses a staged loading method, and the actual deformation value of the hanging basket is calculated using a formula: in, For pouring the first n The elastic deformation value of the hanging basket when the number of blocks is specified; , , For pouring the first n After the concrete block n , n -1、 n Displacement at the front end of bridge section -2; , For the first n , n -1 is the length of bridge section.

8. The construction monitoring method for long-span bridges according to claim 1, characterized in that, After determining the formwork elevation of the bridge structure at each construction stage through backward analysis, the following steps are also included: Stress measuring points were set up at multiple control sections of the bridge to monitor stress changes and stress distribution at multiple control sections during construction. The safety of the completed bridge is determined based on the stress changes and distribution at multiple control sections and the calculated formwork elevation.

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