Temporary horizontal cable force and tension optimization method in arch rib lifting construction process

Abstract

The invention relates to a temporary horizontal cable force and tension optimization method in the arch rib lifting construction process, and the method is characterized in that optimization variables, objective functions and constraint conditions are defined, and a temporary horizontal cable and lifting cable grading tension scheme is formulated based on a differential evolution algorithm by jointly applying a Python programming language and an API interface of a Midaas / Cill NX finite element platform. According to the method, on the premise that it is guaranteed that closure section deformation at the arch springing is well controlled in the lifting process, the iterative calculation efficiency can be greatly improved, the requirement for hardware equipment is low, the temporary horizontal cable force suitable for the arch rib lifting construction process can be economically and rapidly obtained, and therefore it is guaranteed that follow-up closure construction is conducted smoothly, and the construction period is shortened. And meanwhile, graded tensioning of the temporary horizontal cable and the lifting cable is beneficial for guaranteeing the stress safety of the structure in the construction process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bridge construction, and particularly relates to a temporary horizontal cable force and tension optimization method in arch rib lifting construction. BACKGROUND

[0002] With the rapid development of modern engineering technology, steel box arch structures are widely used in long-span bridges and buildings due to their superior mechanical properties and economy. The main construction methods for arch rib installation include support method, swivel method, cantilever assembly method, large segment integral lifting method and incremental launching method. In recent years, the large segment integral lifting method has been increasingly applied due to its high construction efficiency, short construction period and high safety of low-position assembly.

[0003] The temporary horizontal cable force has a great influence on the deformation of the closure section of the arch rib lifting segment before and after lifting construction, which can cause bending, torsion and overall displacement of the closure section, and plays a decisive role in whether the closure can be successfully performed. However, so far there is no specific process for accurately determining the value of the temporary horizontal cable force.

[0004] The tension of the temporary horizontal cable should be completed during the system conversion stage. In the past, the construction method was to directly tension when the arch rib lifting segment was placed on the assembly support, and then lift after completion. However, this method is difficult to ensure construction safety under the condition of high weight of the lifting segment and high lifting cable force.

[0005] Therefore, an automatic optimization method for the temporary horizontal cable force should be developed to optimize the temporary horizontal cable force of the arch rib lifting segment during the system conversion and lifting construction, and a more reasonable temporary horizontal cable tensioning scheme and determination method should be proposed based on this to provide technical support for the smooth construction. SUMMARY

[0006] The purpose of the present application is to overcome the defects and deficiencies of the prior art, and to provide a temporary horizontal cable force and tension optimization method in arch rib lifting construction. The method can solve the problem of large deformation of the closure section of the arch rib lifting segment during lifting construction, and can quickly and conveniently determine the temporary horizontal cable force suitable for arch rib lifting construction, which helps to improve economic efficiency and facilitate smooth construction.

[0007] The technical problem of the present application is solved by the following technical solution: A temporary horizontal cable force and tension optimization method in arch rib lifting construction, the steps of the method are: taking the longitudinal bridge direction as the x-axis, the transverse bridge direction as the y-axis, and the vertical direction as the z-axis. S1, optimization target calculation; the gap Delta between the closure section of the arch rib lifting section and the closure section of the arch foot lifting section is the final optimization target, and the gap Delta between the closure sections is determined by the longitudinal and transverse displacement and three-dimensional rotation of the closure section of the arch rib lifting section. ; ; ; Among them: dx , dy The longitudinal displacement and transverse displacement of the centroid of the arch foot section when lifting to the position are respectively: r x , r y , r z The three-dimensional rotation of the centroid of the arch foot section is respectively: S2, temporary horizontal cable force adjustment; the current calculation condition does not meet the optimization target limit condition, enters the temporary horizontal cable force adjustment module, and starts adjusting the longitudinal and transverse temporary cable forces of the calculation condition, and the adjustment mode is based on the differential evolution algorithm, and the longitudinal and transverse temporary cable forces are automatically adjusted through mutation, evolution and selection; S3, temporary horizontal cable force selection; according to the construction scheme or technical requirement limit value, the optimization target limit value is determined, when the optimization target Delta converges to stability and meets the limit value requirement, the longitudinal and transverse temporary horizontal cable forces under the current calculation condition are taken as the final value; S4, temporary horizontal cable tensioning scheme; on the basis of determining the final longitudinal and transverse temporary horizontal cable force value, since the structure stress and deformation are directly related, the deformation of the temporary horizontal cable tensioning position in the horizontal longitudinal direction can be constrained, the lifting cable force is loaded step by step, the counterforce at the corresponding tensioning position is taken as the temporary horizontal cable force corresponding to the lifting force loading, so that the temporary horizontal cable and lifting cable step-by-step tensioning scheme is formulated.

[0008] Moreover, the method adopts the Midas / Civil NX finite element platform for calculation.

[0009] The advantages and beneficial effects of the present application are: 1, compared with the previous optimization problem, the hardware basis required for the optimization of the temporary horizontal cable force is less, the calculation time is significantly reduced, the single iteration calculation time is less than 1 minute, the obtained temporary horizontal cable force value is accurate, and the closure section deformation of the arch rib lifting section in the lifting construction process can be well controlled.

[0010] 2、The temporary horizontal cable hierarchical tensioning scheme determination method provided by the application has simple operation and good effect, and the obtained temporary horizontal cable and lifting cable hierarchical tensioning scheme can fully meet the engineering conditions of high lifting weight and high temporary horizontal cable force, and ensure that the stress performance of the arch rib lifting segment and the support structure is good.

[0011] 3、The application combines the Python programming language and the Midas / Civil NX finite element platform, and realizes automatic optimization of the temporary horizontal cable force based on the differential evolution algorithm, thereby greatly improving the calculation efficiency and reducing the human workload. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a flowchart of the application; Figure 2 is an arch rib lifting construction layout of an embodiment of the application; Figure 3 is a steel box arch rib finite element model diagram of an embodiment of the application; Figure 4 is a temporary cable force optimization objective function convergence curve diagram of an embodiment of the application; Figure 5 is a temporary horizontal cable hierarchical tensioning scheme calculation boundary condition diagram of an embodiment of the application. DETAILED DESCRIPTION

[0013] The application will be further described in detail below through specific embodiments, and the following embodiments are only descriptive and not limiting, and cannot limit the protection scope of the application.

[0014] As shown in Figure 1 , a temporary horizontal cable force and tensioning optimization method in an arch rib lifting construction process, the innovation of the method is that the steps of the method are as follows: taking the longitudinal bridge direction as the x-axis, the transverse bridge direction as the y-axis, and the vertical direction as the z-axis; S1, optimization target calculation; taking the gap Delta between the closure section of the arch rib lifting segment and the closure section of the arch foot lifting segment as the final optimization target, the gap Delta between the closure sections is determined by five indexes of the longitudinal and transverse displacements and the three-dimensional angles of the closure section of the arch rib lifting segment: ; ; ; Among them: dx , dy respectively, are the longitudinal displacement and the transverse displacement of the centroid of the arch foot section when lifting to the position; r x , r y , r zThe three-way rotation angles of the section around the center of the arch foot are respectively S2, temporary horizontal cable force adjustment; the current calculation condition does not meet the optimization target limit condition, enters the temporary horizontal cable force adjustment module, and begins to adjust the temporary cable forces in the longitudinal and transverse directions of the calculation condition. The adjustment mode is based on a differential evolution algorithm, and the temporary cable forces in the longitudinal and transverse directions are automatically adjusted through mutation, evolution and selection. S3, temporary horizontal cable force selection; according to the construction scheme or technical requirement limit, the optimization target limit is determined, when the optimization target Δ converges to stability and meets the limit requirement, the temporary horizontal cable forces in the longitudinal and transverse directions under the current calculation condition are taken as the final values. S4, temporary horizontal cable tensioning scheme development; based on the determination of the final temporary horizontal cable force values in the longitudinal and transverse directions, since the structure stress and deformation are directly related, the deformation in the horizontal longitudinal direction at the temporary horizontal cable tensioning position can be constrained, the cable force is gradually loaded and improved, the counterforce at the corresponding tensioning position is taken as the temporary horizontal cable force corresponding to the loading of each level of lifting force, and the temporary horizontal cable and lifting cable grading tensioning scheme is developed.

[0015] Engineering profile Taking a through simply-supported basket steel box tied arch bridge in Tianjin as an example, the main bridge has a total length of 421.6 m, a standard bridge width of 60.0 m, and a maximum bridge deck width of 64.0 m, which is the largest single-span length, the widest bridge deck and the heaviest lifting steel box arch bridge in Asia so far. The arch rib lifting section is about 280.0 m long, weighs 7600 t, and the cross-section height at the arch foot is 7.1 m, and the cross-section width is always 4.5 m.

[0016] As shown in Figure 2 , the arch rib is divided into two side arch foot sections and an intermediate lifting section, wherein the two side arch foot sections are completed by in-situ assembly method, and the intermediate section is constructed by first low-position assembly and then overall lifting. Specifically, the construction steps of low-position assembly, system conversion, overall lifting and closure need to be completed in sequence. During the closure construction stage, no closure section is provided, and the eight-cutting method is adopted to make the arch rib lifting smoothly.

[0017] Finite element model The finite element model of the arch rib lifting section is established based on Midas / Civil NX coding modeling, the main arch rib and the wind brace structure are simulated by beam elements, and the temporary horizontal cable force is simulated by node force. The calculation model is shown in Figure 3 .

[0018] The arch rib lifting section is about 280 m long, including two main arch ribs and nine wind braces, and the model has a total of 228 units and 221 nodes.

[0019] The arch rib lifting segment closure section deformation under different temporary horizontal cable forces is extracted by the Python programming language, and the target function value is calculated.

[0020] According to the calculation results of each iteration, the target function convergence curve is drawn, as shown in Figure 4

[0021] Optimization results According to the finite element iterative calculation and results, the temporary horizontal cable force optimization results of the embodiment of the application are 35617.6 kN longitudinally and 5424.2 kN transversely.

[0022] According to the model shown in Figure 5 , the deformation in the horizontal direction at the temporary horizontal cable tensioning position is constrained, the lifting cable force is loaded step by step, the longitudinal counterforce at the corresponding tensioning position is taken as the corresponding longitudinal temporary horizontal cable force when the lifting force is loaded, and the results are shown in Table 1.

[0023] Table 1 Longitudinal temporary horizontal cable force corresponding to each lifting force

[0024] For the transverse temporary horizontal cable force, since its loading process is beneficial to reduce the transverse support reaction of each support, it will not cause hidden dangers to the safety of the structure, so the transverse temporary horizontal cable can be directly tensioned on the support.

[0025] The temporary horizontal cable and lifting cable step-by-step tensioning scheme is formulated as shown in Table 2.

[0026] Table 2 Temporary horizontal cable force and lifting cable force step-by-step loading scheme

[0027] In the embodiment of the application, the temporary horizontal cable force optimization is carried out based on Midas / Civil NX and Python combined with the lifting construction parameters of a certain bridge in Tianjin. The results show that the temporary horizontal cable force optimization results obtained by calculation can well control the arch rib lifting segment closure section deformation in the lifting construction process. Compared with the previous optimization problems, the calculation efficiency is significantly improved, and the single iteration calculation time is less than 1 minute.

[0028] In the embodiment of the application, the temporary horizontal cable and lifting cable step-by-step tensioning scheme and its formulation method in the system conversion stage are given combined with the lifting construction parameters of a certain bridge in Tianjin, which can well solve the support stress overrun problem in the large weight lifting process.

[0029] Although the embodiments and drawings of the application are disclosed for illustrative purposes, those skilled in the art can understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the application and the appended claims, therefore, the scope of the application is not limited to the disclosed contents of the embodiments and drawings.​

Claims

1. A method for optimizing temporary horizontal cable force and tension during arch rib lifting construction, characterized in that: The steps of the method are as follows: take the longitudinal direction of the bridge as the x-axis, the transverse direction of the bridge as the y-axis, and the vertical direction as the z-axis; S1. Optimization target calculation; The final optimization target is the gap Δ between the closure section of the arch rib lifting segment and the closure section of the arch foot lifting segment. The gap Δ between the closure sections is determined by five indicators: longitudinal and transverse displacements and three-dimensional rotation angles of the closure section of the arch rib lifting segment. ； ； ； in: dx , dy These represent the longitudinal and lateral displacements of the centroid of the arch foot section when it is lifted into place. r x , r y , r z These are the three-dimensional rotation angles of the arch foot section around the centroid; S2, Temporary Horizontal Cable Force Adjustment: If the current calculation condition does not meet the optimization target limit conditions, the system enters the temporary horizontal cable force adjustment module to start adjusting the longitudinal and transverse temporary cable forces for the calculation condition. The adjustment method is based on the differential evolution algorithm, which automatically adjusts the longitudinal and transverse temporary cable forces through mutation, evolution, and selection paths. S3. Selection of temporary horizontal cable force: Determine the optimization target limit based on the construction plan or technical requirements limit. When the optimization target Δ converges to a stable state and meets the limit requirements after iterative calculation, the longitudinal and transverse temporary horizontal cable forces under the current calculation conditions are taken as the final values. S4. Temporary horizontal cable tensioning scheme: Based on the final values ​​of the longitudinal and transverse temporary horizontal cable forces, since the stress and deformation of the structure are directly related, the deformation in the horizontal and longitudinal directions at the tensioning position of the temporary horizontal cable can be constrained. The cable force is increased by loading at each stage, and the reaction force at the corresponding tensioning position is used as the temporary horizontal cable force corresponding to each stage of lifting force loading. In this way, a graded tensioning scheme for the temporary horizontal cable and lifting cable is formulated.

2. The method for optimizing temporary horizontal cable force and tension during arch rib lifting construction according to claim 1, characterized in that: The method described uses the Midas / Civil NX finite element platform for calculation.

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