A construction control method for a corrugated steel web prestressed composite box girder cantilever method

Abstract

The application discloses a kind of wave-shaped steel web prestressed composite box girder cantilever method construction control methods, belong to bridge engineering construction control technical field, including the following steps: establishing entity finite element model and determining each construction condition theoretical control parameter;According to the theoretical control parameter, construct linear, stress and wave-shaped steel web spatial position integrated monitoring system;Based on monitoring system, according to construction procedure, carry out multi-condition synchronous monitoring and data acquisition;The data collected are compared with the theoretical calculation value of entity finite element model, and deviation identification and model parameter correction are carried out based on adaptive control method;Determine control index limit value in combination with construction deviation sensitivity analysis;According to deviation analysis result and parameter correction result, adjust the next beam segment construction parameter and cyclic iteration control.The application uses the above method, can maximumly correct and eliminate the influence of construction deviation, ensure construction safety, make bridge state better to reach the reasonable state of design.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering construction control technology, and in particular to a cantilever construction control method for corrugated steel web prestressed composite box girder. Background Technology

[0002] The construction of any bridge, especially a long-span bridge, is a systematic project. Within this system, the construction drawings represent only an ideal state. During construction, the realization of the design intent is influenced by numerous uncertainties, including construction methods, equipment, and external conditions. To maximize the achievement of the design intent, it is crucial to eliminate or minimize the discrepancies between the ideal and actual states during construction. Therefore, real-time identification, prediction, and adjustment of the construction status are essential.

[0003] The cantilever construction of corrugated steel web prestressed composite box girder bridges involves multiple stages, complex procedures, and a long construction period. Each stage inevitably introduces construction deviations, which can lead to difficulties in achieving the bridge's stress state and alignment as designed. Unlike ordinary concrete continuous beam bridges, corrugated steel web continuous beam bridges are structurally a combination of cast-in-place concrete top and bottom slabs with corrugated steel webs. Therefore, in terms of alignment control, they possess the dual characteristics of cantilever assembled steel bridges and concrete continuous beam bridges. The accuracy of the lifting and positioning of the corrugated steel webs directly affects the web's stress; web positioning requires measuring not only the transverse coordinates but also the longitudinal coordinates.

[0004] Existing construction control methods are mostly designed for ordinary concrete box girders, lacking systematic and standardized control measures for the characteristics of corrugated steel web composite structures. This can easily lead to delayed deviation identification and insufficient adjustment basis during construction, making it difficult for the completed bridge to achieve the designed optimal state. Therefore, there is an urgent need for a control method for the cantilever construction of corrugated steel web prestressed composite box girders. Summary of the Invention

[0005] The purpose of this invention is to provide a construction control method for cantilevered composite box girders with corrugated steel web prestressed steel plates, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides a construction control method for cantilevered composite box girders with corrugated steel web prestressed steel plates, comprising the following steps: S1. Establish a solid finite element model and determine the theoretical control parameters for each construction condition; S2. Construct an integrated monitoring system for the spatial position of the linearity, stress, and corrugated steel web based on theoretical control parameters; S3. Based on the monitoring system, conduct simultaneous monitoring and data collection for multiple working conditions according to the construction process; S4. Compare the collected data with the theoretical calculation values ​​of the solid finite element model, and identify the deviation and correct the model parameters based on the adaptive control method. S5. Based on the deviation identification results and combined with the construction deviation sensitivity analysis, determine the control index limits; S6. Based on the deviation analysis results and parameter correction results, adjust the construction parameters of the next beam segment and iterate and control them in a loop.

[0007] Preferably, S1 includes: S11. Based on the bridge design data, establish a solid finite element model of the corrugated steel web prestressed composite box girder bridge; S12. Taking the designed completed bridge state as the target, determine the sub-targets that should be achieved in each construction step according to the design parameters specified in the specifications, and establish a construction process tracking and analysis process to calculate the theoretical values ​​of the control parameters for each working condition during the construction process. S13. Calculate the theoretical formwork elevation for each beam segment.

[0008] Preferably, the solid finite element model is established as follows: the concrete top and bottom slabs are simulated using 3D solid elements, the corrugated steel web is simulated using 2D plate elements, the internal prestressed steel strands are simulated using line elements and automatically coupled with beam elements through automatic mesh generation, and the external prestressed steel strands are simulated using truss elements and tension is achieved by directly applying tension force to the truss elements; the concrete top and bottom slabs and the corrugated steel web are connected by imprinting waveform curves to achieve node sharing and automatic coupling; the external prestressed steel strands are fixed at both ends of the box girder and are steered by diaphragms or by setting steering blocks, and all degrees of freedom are constrained and coupled with the local area of ​​concrete at the anchorage point, while the vertical degrees of freedom of the truss elements and the local area of ​​concrete are constrained at the steering block.

[0009] Preferably, S2 includes: S21. Linearity monitoring involves arranging elevation and deformation measuring points at the top of the cantilever end section of each beam segment and on the top and bottom concrete slabs, and using an automatic leveling instrument for observation, thereby achieving comprehensive monitoring of bridge deflection. S22. Stress monitoring: Vibrating wire concrete strain gauges are arranged at the root of the main beam, mid-span and quarter-point control sections according to the principle of symmetrical arrangement, forming a stress monitoring system for the entire construction process. S23. Spatial position monitoring of corrugated steel web: The absolute spatial coordinates of the corrugated steel web are obtained by measuring the P1 to P9 control points on the top and bottom surfaces of each single-sided block using a total station.

[0010] Preferably, S3 includes: S31. According to the construction steps, the elevation of the control points of each beam segment is measured under the working conditions of hanging basket formwork erection, steel web plate installation, concrete pouring, tensioning before and after, and before and after the second phase of dead load construction. S32. Stress test data collection: According to the construction steps, the stress at the control point is tested after the segmental concrete is poured, before tensioning, during tensioning, after tensioning, before closure, and after the second phase of permanent load paving. S33. Spatial position data acquisition of corrugated steel web: During periods of small temperature changes and stable air temperature, the absolute spatial coordinates of each control node are measured using a total station.

[0011] Preferably, S4 includes: S41. Compare the actual structural deformation and stress data obtained in S3 with the theoretical control values ​​to determine if there is a deviation between the ideal construction state and the actual construction state. If there is no deviation, proceed to the next construction stage. If a deviation is found, further determine whether the deviation is a construction deviation, a measurement deviation, or a parameter deviation. S42. When it is determined that there is a deviation in the calculation model parameters that cannot be ignored, the structural parameters are identified. S43. Substitute the identified model parameters back into the calculation model of S1, re-perform a reasonable state analysis, determine the new ideal state of the completed bridge and the ideal state of construction, and establish a new tracking analysis process.

[0012] Preferably, construction deviations include: deviations in component geometric parameters, which refer to deviations in the cross-sectional dimensions of structural components during the production process; deviations in concrete materials, which refer to deviations in the material properties and workability of the concrete itself; deviations in construction operations, which refer to deviations caused by non-standard construction operations or mechanical failures during the construction process; and deviations in construction management, which refer to deviations caused by changes in the construction plan or structural design that result in construction not being carried out in accordance with the original construction plan or construction organization design.

[0013] Preferably, S5 includes: S51. Sensitivity analysis was conducted on four major types of construction operation deviations that occurred frequently during the cantilever construction stage of corrugated steel web prestressed composite box girder bridges. S52. Determine the limit values ​​of construction deviation control indicators based on the results of sensitivity comparison analysis; S53. After performing deviation analysis on the data, the parameters of the calculation model are corrected to gradually reduce the deviation between the calculated elevation value and the measured value, and the future construction status is predicted.

[0014] Preferably, the construction deviation sensitivity analysis targets four types of deviations: steel web assembly angle deviation, which is simulated in the finite element model by changing the coordinates of the assembly points of the outer single-sided corrugated steel web segments in the mid-span beam segment. The segment construction angle deviation is positive when the upper part of the steel web tilts inward and negative when it tilts outward; prestressed steel bar misalignment, which is simulated by changing the vertical coordinates of the top slab cantilever tendon with the largest eccentricity in the maximum cantilever stage; prestressed steel bar tension loss of control, which is simulated by changing the tension control stress of the prestressed steel bar in the body according to the ratio; and unbalanced construction load, which is simulated by changing the concrete unit weight of the beam segment according to the ratio.

[0015] Preferably, S6 includes: S61. Compare the actual elevation and theoretical elevation of the completed beam segment, and based on a comprehensive analysis of the deviation results, adjust the positioning elevation and planar position of the next cantilever construction beam segment. S62. Positioning control of corrugated steel web is carried out. The positioning of corrugated steel web is divided into horizontal positioning and vertical positioning. Horizontal positioning is a routine construction quality control. Vertical positioning adopts dual control of the vertical elevation of the corrugated steel web installation and the included angle between the front and rear sections. S63. Based on the parameters corrected in S4, redetermine the sub-objectives for each subsequent construction step, establish a new tracking and analysis process, and achieve the goal that the calculations of the tracking and analysis process are consistent with the actual construction, thus realizing the objectives of each stage. After the next beam segment is completed, enter S3 again for monitoring, and repeat this cycle until the construction is completed, so that the completed bridge reaches the reasonable state designed in the end.

[0016] Therefore, the above-mentioned construction control method for cantilevered box girders with corrugated steel web prestressed composite girder has the following beneficial effects: (1) This invention addresses the dual control characteristics of cantilever construction of corrugated steel web prestressed composite box girders by integrating alignment monitoring, stress monitoring and corrugated steel web spatial position monitoring, and combining them with adaptive parameter correction of the finite element refined model to form a complete closed-loop construction control system.

[0017] (2) By conducting sensitivity analysis on four main types of deviations, namely steel web assembly angle deviation, prestressed steel bar misalignment, prestressed steel bar tensioning failure and unbalanced construction load, three control limits were quantitatively determined: steel web assembly angle deviation of 4°, prestressed tensioning control stress deviation of 5%, and concrete unit weight deviation of beam segment of 10%, providing a clear basis for graded early warning and adjustment of construction deviations.

[0018] (3) The method of dual control of vertical elevation of corrugated steel web and the included angle of the front and rear sections is adopted. The elevation control is the main method and the included angle control is the auxiliary method, which effectively avoids the phenomenon of excessively small overlap length of the front and rear steel web sections or large-area enlargement of bolt holes.

[0019] (4) The method of the present invention can correct and eliminate the influence of construction deviations to the greatest extent, ensure construction safety, and make the completed bridge state better reach the reasonable state of the design.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating a cantilever construction control method for a corrugated steel web prestressed composite box girder according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the geometric model of the concrete top and bottom slabs according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the concrete top and bottom slab grid model according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the geometric model of the corrugated steel web according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the corrugated steel web mesh model according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the corrugated steel web mesh model according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the top plate, bottom plate, and corrugated steel web mesh model according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the geometric model of the in-body prestressed steel strands according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the geometric model of the externally prestressed steel strands according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the external prestressed steel strand mesh model according to an embodiment of the present invention; Figure 11 This is a schematic diagram of the constraint at the diaphragm in an embodiment of the present invention; Figure 12 This is a schematic diagram of the constraint at the anchorage point in an embodiment of the present invention; Figure 13 This is a schematic diagram of the solid finite element model of a corrugated steel web prestressed composite box girder bridge according to an embodiment of the present invention; Figure 14 This is a diagram showing the angle deviation of the steel web assembly in an embodiment of the present invention. Detailed Implementation

[0022] 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.

[0023] It should be noted that similar labels 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.

[0024] Example like Figure 1 As shown, this invention provides a construction control method for cantilevered composite box girders with corrugated steel web prestressed steel plates, comprising the following steps: S1. Establish a solid finite element model and determine the theoretical control parameters for each construction condition.

[0025] In this embodiment, S1 includes: S11. Based on the bridge design data, establish a solid finite element model of the corrugated steel web prestressed composite box girder bridge. Simplify the structural modeling without affecting the analysis accuracy. The concrete top and bottom slabs are simulated using 3D solid elements. When generating the solid mesh, if it is a variable cross-section continuous beam bridge, use automatic mesh generation, referring to... Figures 2-3 The corrugated steel web was simulated using 2D plate elements, with meshes divided for four thicknesses: 12mm, 14mm, 16mm, and 20mm, as referenced. Figures 4-5 The prestressed steel strands within the body are simulated using line elements and automatically coupled with beam elements through automatic mesh generation, referring to... Figure 8 The external prestressed steel strands are simulated using truss elements, and tension is achieved by directly applying tension force to the truss elements, referring to... Figures 9-10 .

[0026] The concrete top and bottom slabs and the corrugated steel web are coupled by imprinting the corrugated steel web's waveform curve onto the concrete top and bottom slabs, enabling shared nodes and automatic coupling between the two materials. This allows both materials to participate in the overall structural work without considering relative slippage. (Refer to...) Figures 6-7 External prestressed steel strands are fixed at both ends of the box girder, and steering is achieved through diaphragms or steering blocks, as shown in the reference. Figure 11At the anchorage point, all degrees of freedom are constrained and coupled with the local concrete region; at the turning block, the truss element and the vertical degrees of freedom of the local concrete region are constrained, referring to... Figure 12 .

[0027] The final solid finite element model of the corrugated steel web prestressed composite box girder bridge is as follows: Figure 13 As shown.

[0028] S12. Determine the sub-objectives for each construction step and establish a tracking and analysis process: First, taking the designed completed bridge state as the target, determine the sub-objectives to be achieved for each construction step according to the design parameters specified in the specifications, and establish a construction process tracking and analysis process to calculate the theoretical values ​​of the control parameters for each working condition during construction, including the theoretical deflection of each beam segment, the stress of the control section, and the spatial positioning parameters of the corrugated steel web. The construction process tracking and analysis process is a construction management process that combines theoretical calculation, on-site measurement, error analysis, and real-time adjustment.

[0029] S13. Calculate the theoretical formwork elevation for each beam segment. The formula for calculating the formwork elevation is as follows: In the formula: Indicates beam segment The elevation of the vertical mold; Indicates beam segment Design elevation; Indicates beam segment The theoretical pre-throw value; Indicates beam segment Additional pre-throw value; Indicates beam segment Vertical displacement due to deformation of the hanging basket; This indicates the construction adjustment value, which is mainly adjusted based on two situations: when the beam segment If the formwork elevation of the first section of the beam does not conform to the theoretical elevation given by the monitoring system, and the deviation is significant, the formwork elevation needs to be corrected to ensure the alignment of the completed bridge; beam section When the theoretical deformation and actual deformation of the beam segment after concrete pouring and tensioning differ by more than 20%, the beam segment needs to be adjusted. The elevation of the formwork was adjusted.

[0030] The theoretical pre-camber value is set according to the prestressed concrete bending member. The pre-camber value of the prestressed member is equal to the difference between the long-term deflection value calculated according to the combination of short-term load effects and the long-term anti-camber value of the prestress. When erecting the formwork, the bottom plate elevation is calculated according to the elevation of the hanging basket control point and the design height of the main beam section.

[0031] S2. Construct an integrated monitoring system for the spatial position of the linearity, stress, and waveform of the steel web based on theoretical control parameters.

[0032] In this embodiment, S2 includes: S21. Alignment Monitoring Point Layout and Instrument Configuration: Comprehensive deflection monitoring of the bridge will be conducted. Elevation monitoring points will be set up at the top of the cantilever end section of each beam segment. Short reinforcing bars will be pre-embedded at the monitoring points and marked with red paint. Five deformation monitoring points will be arranged on the concrete top slab and three on the bottom slab. The elevation monitoring points will be arranged 10cm away from the front end of the block. Φ16 steel bars will be spot-welded vertically to the upper and lower layers of reinforcing bars on the top slab, ensuring verticality. The steel bars at the monitoring points will protrude 5cm from the concrete surface of the box girder. The measuring heads will be ground smooth and marked with red paint. Alignment observation will be conducted using an automatic level with a mean error of ±1mm per kilometer of elevation difference.

[0033] S22. Stress monitoring point layout and instrument configuration.

[0034] The arrangement of stress measurement points follows these principles: symmetrical arrangement in both transverse and longitudinal directions to increase the comparability and reliability of results; identification of the most dangerous locations through simulation calculations, selection of the foundation for stress monitoring sections, and determination of the stress envelope diagram throughout the construction process; full understanding of the engineering design intent; avoidance of the Saint-Venant area when selecting sections; and meeting the needs of completion and final load tests and subsequent structural health monitoring.

[0035] A total of seven stress testing sections were arranged on the superstructure of the main bridge: the 1 / 2L section of the main span (L represents the standard span of the bridge, and the 1 / 2L section is the main bridge section located at 1 / 2 of the standard span), the 1 / 4L section, the root section of the box girder, the 1 / 2 section of the side span, and the 1 / 4 section. Six stress measuring points were arranged at the root section and the mid-span section of the main girder (three on the top plate and three on the bottom plate), and nine measuring points were arranged at the quarter-span sections (three on the top plate, three on the bottom plate, and three on the web). Long... The vibrating wire concrete strain gauge and its matching vibrating wire reading instrument have good periodicity, stability and high accuracy; the embedded vibrating wire sensor is tied to the main reinforcement of the structure with fine wire in the predetermined test direction before concrete pouring. The fine wire is tied 5mm inside the strain gauge's force handle. The test lead is led out along the reinforcement to the concrete surface at the cantilever end of the box girder; the surface sensor is installed by welding or bonding. The sensor base is installed through a standard rod and is installed and debugged within 48 hours before the steel web of each segment is installed in place.

[0036] S23. Spatial position monitoring point layout of corrugated steel web: The positioning of corrugated steel web measures not only the transverse coordinates but also the longitudinal coordinates. Points P1 to P9 are measured on each single-side block, where P1 to P6 are the top surface measuring points, and P7 to P9 are the bottom surface measuring points. H is the height of the corrugated steel web, and h is the height of P7 to P9 from the bottom of the web. The spatial position test uses a total station to measure the absolute spatial coordinates of each control node.

[0037] S3. Based on the monitoring system, conduct simultaneous monitoring and data collection for multiple working conditions according to the construction process.

[0038] In this embodiment, S3 includes: S31. Alignment Measurement Data Acquisition: The frequency of alignment measurement is related to the construction steps and is arranged for measurement in the following construction stages: 1. Moving the formwork forward and erecting the formwork according to the elevation provided by the monitoring team; 2. After the steel web plate is installed and positioned; 3. After the top and bottom slabs are poured with concrete; 4. Measuring the elevation of all control points of the constructed beam segments before tensioning; 5. Measuring the elevation of all control points of the constructed beam segments again after tensioning; 6. Measuring the elevation of all control points of the constructed beam segments before the second phase of dead load construction; 7. Testing the elevation of all control points of the beam segments after the second phase of dead load construction. Deflection monitoring is carried out before 9:00 AM when the temperature is low to minimize the impact of temperature. Each segment is monitored at least once to observe the change process of deflection at each point and the beam axis curve of the box girder.

[0039] S32. Stress Test Data Acquisition: The frequency of stress testing is related to the construction steps and is arranged for measurement in the following construction stages: 1. Stress at control points after concrete pouring of the main beam segment; 2. Stress at control points of all constructed beam segments before tensioning; 3. Real-time monitoring of stress changes during prestressing tensioning; 4. Stress at control points of all constructed beam segments again after tensioning; 5. Stress at control points of all constructed beam segments before closure; 6. Stress at control points of all constructed beam segments after completion of the second-phase dead load paving. Stress monitoring is scheduled to be completed before sunrise to avoid the influence of uneven temperature field caused by sunlight. The strain gauge readings are checked before installation and again after installation. The strain gauges are tested immediately after the initial setting of concrete to ensure they are functioning properly. The sensor plug is inserted into the reading instrument socket for about 3 seconds before taking the reading.

[0040] S33. Data acquisition of spatial position of corrugated steel web: The spatial position of corrugated steel web is tested by measuring the absolute spatial coordinates of each control node using a total station. The measurement is carried out during a period of small temperature change and stable air temperature to accurately grasp the lateral and longitudinal coordinate status of the corrugated steel web.

[0041] S4. Compare the collected data with the theoretical calculation values ​​of the solid finite element model, and perform deviation identification and model parameter correction based on the adaptive control method.

[0042] In this embodiment, S4 includes: S41. Comparison of measured values ​​and theoretical values ​​and identification of deviation types: Compare the actual structural deformation and stress data obtained in S3 with the theoretical values ​​calculated by the S1 tracking analysis process to determine whether there is a deviation between the ideal construction state and the actual construction state. If there is no deviation, proceed to the next construction stage. If a deviation is found, further determine whether the deviation is a construction deviation, measurement deviation, or parameter deviation.

[0043] Construction deviations include: deviations in component geometric parameters, mainly referring to deviations in the cross-sectional dimensions of structural components during production; deformation or damage to structural components during transportation can also lead to such deviations, which directly result in deviations in cross-sectional properties, thereby affecting structural deformation and internal forces; deviations in concrete materials, mainly referring to deviations in the material properties and workability of concrete itself, such as insufficient concrete strength, changes in concrete elastic modulus and unit weight; deviations in construction operations, mainly referring to deviations caused by non-standard construction operations or mechanical failures, such as deviations in the steel web assembly angle, over-tensioning, under-tensioning, asymmetrical prestressing, changes in the position of prestressed steel bars, deviations in corrugated pipe installation, and deformation of anchorages; and deviations in construction management, mainly referring to deviations caused by changes in the construction plan or structural design that prevent construction from being carried out according to the original construction plan or construction organization design, such as premature construction of some beam segments, changes in construction technology, and changes in structural design.

[0044] S42. Structural Parameter Identification: When it is determined that there is a deviation in the calculation model parameters that cannot be ignored, the structural parameters are identified. The structural parameters that need to be identified and adjusted include the unit weight of the main beam, the cross-sectional dimensions of the main beam, the elastic modulus of the main beam, the actual weight of the hanging basket, temperature, and construction load, etc. The alignment control itself is a cyclical process of construction-measurement-identification-correction-prediction-construction. First, based on the analysis and calculation of the structural model, the structural parameters are identified and adjusted to determine the theoretical positioning elevation of the box girder and implement it. Then, the elevation and planar position of the completed beam segments are monitored.

[0045] S43. Model Parameter Correction and Reasonable State Reanalysis: Substitute the identified model parameters back into the calculation model of S1, re-analyze the reasonable state, determine the new ideal state of the completed bridge and the ideal state of construction, and establish a new tracking analysis process; rely on the continuously updated feedback measurement data during construction to track and analyze the relevant parameters of the process, so that the calculation process is adapted to the actual construction. After the adaptive calculation process is relatively consistent with the actual construction process, the control alignment requirements are met, and a new cycle begins until the parameter deviation is eliminated or the construction is completed.

[0046] S5. Based on the deviation identification results, combined with the construction deviation sensitivity analysis, determine the control index limits.

[0047] In this embodiment, S5 includes: S51. Sensitivity analysis was conducted on four major construction operation deviations that occurred frequently during the cantilever construction stage of corrugated steel web prestressed composite box girder bridges. For each type of deviation, the changes in main beam deflection, main beam compressive stress, steel web shear stress, and structural stability were compared and analyzed at the maximum cantilever stage and the completed bridge stage.

[0048] The four main types of construction operation deviations include: deviation in the steel web assembly angle, which is simulated in a finite element model by changing the coordinates of the assembly points of the outer single-sided corrugated steel web segments of the mid-span beam segment, as referenced. Figure 14 , angular deviation The coordinates of each assembly point are calculated by rotating the construction segment around the end assembly point of the steel web of the previous segment by the corresponding angle, taking 2°, 4°, and 6° respectively. The segment construction angle deviation is positive when the upper part of the steel web tilts inward and negative when it tilts outward. The prestressed steel bar deviation is simulated by changing the vertical coordinate of the top slab cantilever bundle with the largest eccentricity in the maximum cantilever stage, deviating from the original design vertical position by 2cm, 4cm, and 6cm. The prestressed steel bar tension loss is simulated by changing the tension control stress of the prestressed steel bar in the body by a ratio, with the tension control stress increasing or decreasing by 5%, 10%, and 15%. The unbalanced construction load is simulated by changing the concrete unit weight of the beam segment by a ratio, with the concrete unit weight increasing or decreasing by 5%, 10%, and 15%.

[0049] S52. Determine the limit values ​​of construction deviation control indicators based on the results of sensitivity comparison analysis and relevant specifications.

[0050] The results of the sensitivity comparison analysis are as follows: When the steel web assembly angle deviation is greater than 4°, the stress of the beam segment at the deviation point changes significantly, and even large tensile stress is generated locally. The local tensile stress of the beam segment at the deviation point is greater than the allowable tensile stress of 1.85MPa in C50 concrete specifications, which can easily lead to cracks in the beam and slab, affecting construction safety and bridge quality. Therefore, a steel web assembly angle deviation of 4° is used as the control limit. When the prestressing tension control stress deviation is ±5%, the deflection of the main beam in both the maximum cantilever stage and the completed bridge stage changes significantly. The larger the deviation, the greater the deflection change, which can easily lead to difficulties in bridge closure. Therefore, a prestressing steel tension control stress deviation of 5% is used as the control limit. When the concrete unit weight of the beam segment changes by 10%, the deflection of the mid-span beam segment in both the maximum cantilever stage and the completed bridge stage changes significantly. The larger the change in the unit weight of the beam segment, the greater the deflection change, which has a certain impact on the structural alignment. Therefore, a concrete unit weight deviation of 10% is used as the control limit.

[0051] S53. After performing deviation analysis on the data, the parameters of the calculation model are corrected to gradually reduce the deviation between the calculated elevation value and the measured value, and to predict the future construction status. The deviation of the line shape does not need to be adjusted when it is within the specified value, but it needs to be adjusted when the deviation exceeds the control value or the cumulative deviation is too large. During the construction process, the tensioning of the prestressed steel bars is mainly controlled to prevent over-tensioning and under-tensioning. During the monitoring and control of the line shape and stress, the main parameters such as the prestressing tension control stress, the deviation of the steel web assembly angle and the unbalanced construction load are tracked and detected.

[0052] S6. Based on the deviation analysis results and parameter correction results, adjust the construction parameters of the next beam segment and iterate and control them in a loop.

[0053] In this embodiment, S6 includes: S61. Compare the actual elevation and theoretical elevation of the completed beam segment. Based on a comprehensive analysis of the deviation results, adjust the positioning elevation and planar position of the next cantilever construction beam segment.

[0054] Adjusting the formwork elevation during construction is the most direct way to control the bridge alignment. In reality, errors caused by various factors can be corrected by adjusting the formwork elevation. The theoretical formwork elevation calculated by structural simulation is only theoretical data. In reality, uncertain factors such as concrete unit weight, elastic modulus, shrinkage and creep, and construction load will affect the theoretical calculation. Therefore, the measured values ​​and theoretical values ​​are compared comprehensively, and the theoretical values ​​are corrected according to the differences before determining the formwork elevation for the next stage.

[0055] S62. Positioning control of corrugated steel web. Positioning of corrugated steel web is divided into lateral positioning and vertical positioning. Lateral positioning is a routine construction quality control measure. Vertical positioning adopts dual control of the vertical elevation of the corrugated steel web installation and the included angle between the front and rear sections, with elevation control as the main method and the included angle between the front and rear sections as the secondary method.

[0056] When adding a new N+1 segment to the corrugated steel web, it is necessary to consider not only the deformation of the N segment but also the tangential deformation of the N+1 segment. The elevation of the N+1 segment is usually controlled by the angle or slope between the N and N segments.

[0057] Control of the corrugated steel web includes controlling the depth of the shear keys embedded in the bottom and top plates, as well as controlling the overlap between the front and rear sections of the corrugated steel web. Concrete pouring causes downward deflection at the front end of the formwork. At this point, the steel web is already welded and fixed to the front section. The relative displacement between the concrete bottom and top plates and the corrugated steel web causes changes in the embedment depth of the corrugated steel web. This relative displacement is considered during the erection of the bottom and top plates to control the embedment depth of the steel web in the concrete.

[0058] This control method can effectively control the positioning and installation accuracy of the front and rear steel web plates, avoiding the phenomenon of excessively small overlap length of the front and rear steel web plates or large-area enlargement of bolt holes.

[0059] S63. Based on the parameters corrected in S4, redetermine the sub-objectives for each subsequent construction step, establish a new tracking and analysis process, and repeat the above process until the calculation of the tracking and analysis process is consistent with the actual construction. The objectives of each stage can then be achieved. If necessary, adjustments and controls are made. After the next beam segment is completed, S3 is entered again for monitoring. This process is repeated until the construction is completed, and finally the completed bridge reaches the reasonable state designed for it.

[0060] Therefore, the above-mentioned cantilever construction control method for corrugated steel web prestressed composite box girder can maximize the correction and elimination of the influence of construction deviations, ensure construction safety, and enable the completed bridge to better achieve the reasonable design state.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A construction control method for cantilevered composite box girders with corrugated steel web prestressed concrete, characterized in that, Includes the following steps: S1. Establish a solid finite element model and determine the theoretical control parameters for each construction condition; S2. Construct an integrated monitoring system for the spatial position of the linearity, stress, and corrugated steel web based on theoretical control parameters; S3. Based on the monitoring system, conduct simultaneous monitoring and data collection for multiple working conditions according to the construction process; S4. Compare the collected data with the theoretical calculation values ​​of the solid finite element model, and identify the deviation and correct the model parameters based on the adaptive control method. S5. Based on the deviation identification results and combined with the construction deviation sensitivity analysis, determine the control index limits; S6. Based on the deviation analysis results and parameter correction results, adjust the construction parameters of the next beam segment and iterate and control them in a loop.

2. The cantilever construction control method for a corrugated steel web prestressed composite box girder according to claim 1, characterized in that, S1 includes: S11. Based on the bridge design data, establish a solid finite element model of the corrugated steel web prestressed composite box girder bridge; S12. Taking the designed completed bridge state as the target, determine the sub-targets that should be achieved in each construction step according to the design parameters specified in the specifications, and establish a construction process tracking and analysis process to calculate the theoretical values ​​of the control parameters for each working condition during the construction process. S13. Calculate the theoretical formwork elevation for each beam segment.

3. The cantilever construction control method for a corrugated steel web prestressed composite box girder according to claim 2, characterized in that, The solid finite element model is established as follows: the concrete top and bottom slabs are simulated using 3D solid elements, the corrugated steel web is simulated using 2D plate elements, the internal prestressed steel strands are simulated using line elements and automatically coupled with beam elements through automatic mesh generation, and the external prestressed steel strands are simulated using truss elements, with tension applied directly to the truss elements to achieve tensioning of the external strands; the concrete top and bottom slabs and the corrugated steel web are connected by imprinting waveform curves to achieve node sharing and automatic coupling; the external prestressed steel strands are fixed at both ends of the box girder, and are steered by diaphragms or by setting steering blocks, and all degrees of freedom are constrained and coupled with the local area of ​​concrete at the anchorage point, while the vertical degrees of freedom of the truss elements and the local area of ​​concrete are constrained at the steering block.

4. The cantilever construction control method for a corrugated steel web prestressed composite box girder according to claim 1, characterized in that, S2 include: S21. Linearity monitoring involves arranging elevation and deformation measuring points at the top of the cantilever end section of each beam segment and on the top and bottom concrete slabs, and using an automatic leveling instrument for observation, thereby achieving comprehensive monitoring of bridge deflection. S22. Stress monitoring: Vibrating wire concrete strain gauges are arranged at the root of the main beam, mid-span and quarter-point control sections according to the principle of symmetrical arrangement, forming a stress monitoring system for the entire construction process. S23. Spatial position monitoring of corrugated steel web: The absolute spatial coordinates of the corrugated steel web are obtained by measuring the P1 to P9 control points on the top and bottom surfaces of each single-sided block using a total station.

5. The cantilever construction control method for a corrugated steel web prestressed composite box girder according to claim 1, characterized in that, S3 include: S31. According to the construction steps, the elevation of the control points of each beam segment is measured under the working conditions of hanging basket formwork erection, steel web plate installation, concrete pouring, tensioning before and after, and before and after the second phase of dead load construction. S32. Stress test data collection: According to the construction steps, the stress at the control point is tested after the segmental concrete is poured, before tensioning, during tensioning, after tensioning, before closure, and after the second phase of permanent load paving. S33. Spatial position data acquisition of corrugated steel web: During periods of small temperature changes and stable air temperature, the absolute spatial coordinates of each control node are measured using a total station.

6. The cantilever construction control method for a corrugated steel web prestressed composite box girder according to claim 1, characterized in that, S4 include: S41. Compare the actual structural deformation and stress data obtained in S3 with the theoretical control values ​​to determine if there is a deviation between the ideal construction state and the actual construction state. If there is no deviation, proceed to the next construction stage. If a deviation is found, further determine whether the deviation is a construction deviation, a measurement deviation, or a parameter deviation. S42. When it is determined that there is a deviation in the calculation model parameters that cannot be ignored, the structural parameters are identified. S43. Substitute the identified model parameters back into the calculation model of S1, re-perform a reasonable state analysis, determine the new ideal state of the completed bridge and the ideal state of construction, and establish a new tracking analysis process.

7. The cantilever construction control method for a corrugated steel web prestressed composite box girder according to claim 6, characterized in that, Construction deviations include: deviations in component geometric parameters, referring to deviations in the cross-sectional dimensions of structural components during the production process; deviations in concrete materials, referring to deviations in the material properties and workability of concrete itself; deviations in construction operations, referring to deviations caused by non-standard construction operations or mechanical failures during the construction process; and deviations in construction management, referring to deviations caused by changes in the construction plan or structural design that result in construction not being carried out in accordance with the original construction plan or construction organization design.

8. The cantilever construction control method for a corrugated steel web prestressed composite box girder according to claim 1, characterized in that, S5 include: S51. Sensitivity analysis was conducted on four major types of construction operation deviations that occurred frequently during the cantilever construction stage of corrugated steel web prestressed composite box girder bridges. S52. Determine the limit values ​​of construction deviation control indicators based on the results of sensitivity comparison analysis; S53. After performing deviation analysis on the data, the parameters of the calculation model are corrected to gradually reduce the deviation between the calculated elevation value and the measured value, and the future construction status is predicted.

9. The cantilever construction control method for a corrugated steel web prestressed composite box girder according to claim 8, characterized in that, Sensitivity analysis of construction deviations targets four types of deviations: deviation of steel web assembly angle, which is simulated in a finite element model by changing the coordinates of the assembly points of the outer single-sided corrugated steel web segments in the mid-span beam segment. The segment construction angle deviation is positive when the upper part of the steel web tilts inward and negative when it tilts outward; prestressed steel bar misalignment, which is simulated by changing the vertical coordinates of the top slab cantilever tendon with the largest eccentricity in the maximum cantilever stage; prestressed steel bar tension loss of control, which is simulated by changing the tension control stress of the prestressed steel bar in the body according to the ratio; and unbalanced construction load, which is simulated by changing the concrete unit weight of the beam segment according to the ratio.

10. The cantilever construction control method for a corrugated steel web prestressed composite box girder according to claim 1, characterized in that, S6 include: S61. Compare the actual elevation and theoretical elevation of the completed beam segment, and based on a comprehensive analysis of the deviation results, adjust the positioning elevation and planar position of the next cantilever construction beam segment. S62. Positioning control of corrugated steel web is carried out. The positioning of corrugated steel web is divided into horizontal positioning and vertical positioning. Horizontal positioning is a routine construction quality control. Vertical positioning adopts dual control of the vertical elevation of the corrugated steel web installation and the included angle between the front and rear sections. S63. Based on the parameters corrected in S4, redetermine the sub-objectives for each subsequent construction step, establish a new tracking and analysis process, and achieve the goal that the calculations of the tracking and analysis process are consistent with the actual construction, thus realizing the objectives of each stage. After the next beam segment is completed, enter S3 again for monitoring, and repeat this cycle until the construction is completed, so that the completed bridge reaches the reasonable state designed in the end.

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