A design optimization method for ultra-long packing racks based on stiffness matching

Abstract

This invention discloses a design optimization method for ultra-long packing racks based on stiffness matching. It pre-matches the characteristic stiffness coefficients of the packed components and the packing rack by independently extracting them. It innovatively introduces only-compression nonlinear connection units to construct a collaborative mechanical model, strictly controlling the vertical relative displacement of the contact points. The invention includes the following steps: extracting the characteristic stiffness coefficient K1 of the packed components; extracting the characteristic stiffness coefficient K2 of the packing rack; performing stiffness pre-optimization at K2 = 1.05~1.2 times K1; establishing a collaborative model by arranging only-compression nonlinear connection units with a spacing of 500-800mm; and determining the design qualification using contact point displacement and member stress as dual indicators. This invention can reduce the amount of steel used in ultra-long packing racks (span ≥ 20m), shorten the design cycle, and avoid the risk of component falling due to stiffness mismatch. It is applicable to the transportation and packing design of bridges, industrial plants, and ultra-high-rise steel structures.

Description

Technical Field

[0001] This invention relates to the field of steel structure construction technology, and more specifically, to a design optimization method for ultra-long packing racks based on stiffness matching. Background Technology

[0002] Extra-long packing racks (span ≥ 20m) are core support structures in the transportation of large steel structures, and their design quality directly affects the safety of component transportation and project costs. Currently, the design of extra-long packing racks mainly adopts the empirical analogy method and the simplified mechanical calculation method: the empirical analogy method refers to the parameters of conventional racks with a span < 15m and scales them up proportionally, with key parameters highly dependent on the designer's experience; the simplified mechanical calculation method only verifies the vertical static balance, ignoring the coordinated deformation effect between the components and the rack.

[0003] The existing technology has the following serious defects:

[0004] Insufficient design basis and imbalance between safety and economy: The lack of specific analysis on the mechanical properties of ultra-long spans can easily lead to structural redundancy and waste of steel, or cause safety hazards such as bending of support columns and failure of nodes due to oversimplification.

[0005] Lack of stiffness matching mechanism: The stiffness (EI) coordination between the packing frame and the packed components is not quantified. Due to design deviations in the moment of inertia I of the cross section, the deformation of the two is not coordinated under their own weight. When the deformation difference exceeds the threshold, the components separate from the frame, and the load is concentrated on the end support columns, leading to the risk of fracture or component fall.

[0006] The stability calculation is one-sided: it ignores the uneven distribution of the component's self-weight, the impact of the hoisting dynamic load, and the additional bending moment due to the shift of the center of gravity, which can easily lead to lateral instability under ultra-long spans.

[0007] Low accuracy of contact simulation: Traditional finite element analysis uses rigid constraints to simulate the contact relationship between components and the frame, resulting in false stress in the calculation results, which cannot accurately reflect the actual stress state.

[0008] In summary, existing technologies cannot solve the problem of deformation coordination between ultra-long packing frames and components. There is an urgent need for a design method that can accurately quantify stiffness matching relationships, predict deformation separation risks, and optimize key parameters. Summary of the Invention

[0009] To address the problems existing in the prior art, the purpose of this invention is to provide a design optimization method for ultra-long packing racks based on stiffness matching. Through independent stiffness extraction, pre-matching optimization, and high-precision collaborative analysis, a safe and economical design for ultra-long packing racks can be achieved.

[0010] The present invention adopts the following technical solution:

[0011] A design optimization method for ultra-long packing racks based on stiffness matching includes the following steps:

[0012] S1. Extraction of stiffness features of the packaged component

[0013] A simplified beam element model of the packaged component is established. A hinged support constraint is applied at the end position where the component contacts the packaging frame. Only the self-weight load of the component is applied. The deflection curve of the component in the long axis direction is calculated. The characteristic stiffness coefficient K1 of the component is extracted based on the curve characteristics.

[0014] S2. Extraction of stiffness features of the packing frame

[0015] An independent finite element model of the packing frame is established. Constraints are applied at the lifting points of the frame. Only the self-weight of the frame is applied. The deflection curve of the frame along its long axis is calculated. Based on the curve features, the characteristic stiffness coefficient K2 of the frame is extracted.

[0016] S3, Stiffness Matching Pre-optimization

[0017] Compare the characteristic stiffness coefficients K1 and K2, and adjust the cross section of the frame load-bearing beam or the support layout, K2 > K1;

[0018] S4. Construction and Analysis of Component-Frame Collaborative Model

[0019] Based on the optimized parameters in step S3, a joint simulation model is established. In the contact area between the component and the frame, only nonlinear connection elements under pressure are arranged. Actual hoisting constraints and vertical loads including dynamic load coefficients are applied. The model is solved and the vertical relative displacement Δ between the component and the frame is monitored.

[0020] S5. Solution Verification and Output

[0021] If the vertical relative displacement Δ at the contact point is less than or equal to the preset threshold and the stress of the frame members is less than or equal to 0.9 times the material yield strength, the design is deemed qualified. If the standard is not met, return to step S3 to adjust the frame parameters until the requirements are met, and finally generate the frame construction drawings and finite element analysis report.

[0022] Furthermore, in step S5, the preset threshold is 1.0 mm.

[0023] Furthermore, in step S4, nonlinear connection units are used to simulate a contact state that is only under compression and not under tension, and the spacing between the nonlinear connection units is 500-800mm.

[0024] Furthermore, in step S3, the frame characteristic stiffness coefficient K2 is 1.05 to 1.2 times the component characteristic stiffness coefficient K1.

[0025] Furthermore, in step S5, the spacing between the support columns is adjusted first during iterative optimization.

[0026] Beneficial effects

[0027] Stiffness matching is taken as the core principle of the design of ultra-long packing racks. By controlling the stiffness ratio by quantification, the risk of components separating from the frame due to stiffness mismatch is avoided.

[0028] The contact relationship is simulated by using only nonlinear connection elements under pressure, which eliminates the spurious stress caused by traditional rigid constraints.

[0029] While ensuring structural safety, the amount of steel used in the packing frame can be reduced, and the design cycle can be shortened.

[0030] It is applicable to various types of ultra-long steel structure components, including H-beams, box columns, trusses, and composite steel structures, and can be directly applied to general-purpose finite element software. Attached Figure Description

[0031] Figure 1 This is an optimized flowchart of an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of a component-framework collaborative model according to an embodiment of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] As shown in the figure, this invention discloses a design optimization method for ultra-long packing racks based on stiffness matching, including the following steps:

[0035] S1, Extraction of stiffness features of packaged component 1

[0036] A simplified beam element model of the packaged component 1 is established. A hinged support constraint is applied at the end position where component 1 contacts the packaging frame 2. Only the self-weight load of the component is applied. The deflection curve of the component in the long axis direction is calculated. The characteristic stiffness coefficient K1 of the component is extracted based on the curve characteristics.

[0037] S2, Extraction of stiffness features of the packing frame 2

[0038] An independent finite element model of the packing frame 2 is established. Constraints are applied at the lifting points of the frame. Only the self-weight load of the frame is applied. The deflection curve of the frame along the long axis is calculated. Based on the curve features, the characteristic stiffness coefficient K2 of the frame is extracted.

[0039] S3, Stiffness Matching Pre-optimization

[0040] Compare the characteristic stiffness coefficients K1 and K2, and adjust the cross section of the frame load-bearing beam or the support layout, K2 > K1;

[0041] S4. Construction and Analysis of Component-Frame Collaborative Model

[0042] Based on the optimized parameters in step S3, a joint simulation model is established. In the contact area between the component and the frame, only nonlinear connection elements 3 under pressure are arranged. Actual hoisting constraints and vertical loads including dynamic load coefficients are applied. The model is solved and the vertical relative displacement Δ of the contact point between the component and the frame is monitored.

[0043] S5. Solution Verification and Output

[0044] If the vertical relative displacement Δ at the contact point is less than or equal to the preset threshold and the stress of the frame members is less than or equal to 0.9 times the material yield strength, the design is deemed qualified. If the standard is not met, return to step S3 to adjust the frame parameters until the requirements are met, and finally generate the frame construction drawings and finite element analysis report.

[0045] This invention extracts the characteristic stiffness K1 / K2 from the major axis deflection curve under self-weight, which can accurately reflect the true overall stiffness of irregularly shaped components, variable cross-section components, and frames with nodes, avoiding the problem of large deviation between theoretical and actual values.

[0046] The packaged components are constrained by the "contact end hinge support", which accurately simulates the boundary conditions of the components being supported by the frame during hoisting. The extracted deformation features are highly consistent with the actual working conditions.

[0047] By employing nonlinear connection elements subjected only to compression, the contact characteristics of the two components, which "transmit only compression, not tension, and can be partially separated," are accurately reproduced. This solves the fatal flaw of traditional binding / coupling elements that overestimate the connection stiffness, leading to dangerously biased calculation results.

[0048] The collaborative analysis phase introduces dynamic load coefficients and actual hoisting constraints, rather than ideal static conditions, so that the calculation results can directly reflect the stress and deformation during the actual hoisting process.

[0049] Simultaneously monitoring the vertical relative displacement Δ at the contact point (directly reflecting the stiffness matching effect and avoiding additional stress / permanent deformation of components due to excessive deformation of the frame) and the stress of the frame members (ensuring the strength and safety of the frame itself) is much more comprehensive than the traditional design that only verifies the strength of the frame.

[0050] In one embodiment of the present invention, in step S5, the preset threshold is 1.0 mm.

[0051] In one embodiment of the present invention, in step S4, the nonlinear connection unit 3 is used to simulate a contact state that is only under pressure and not under tension, and the spacing between the nonlinear connection units is 500-800mm.

[0052] This invention can accurately simulate the local separation phenomenon and load redistribution law caused by excessive local deformation of the frame during hoisting, which is something that traditional methods cannot achieve at all.

[0053] The 500-800mm spacing matches the local stiffness characteristics of most engineering components (such as steel structure beams, precast concrete beams, wind turbine blades, etc.), and can accurately capture continuous load transfer paths and local deformation characteristics.

[0054] In one embodiment of the present invention, in step S3, the frame characteristic stiffness coefficient K2 is 1.05 to 1.2 times the component characteristic stiffness coefficient K1.

[0055] The 1.05-fold lower limit precisely covers all the uncertainties in the above-mentioned projects, ensuring that under any extreme working conditions, the frame is always a "flexible body" that bears the main deformation, and the components are always a "rigid body" that is protected, thus eliminating the problem of additional stress generated by the deformation of the frame leading to the components.

[0056] The 1.2 times upper limit precisely hits the cost-effectiveness inflection point between "protection effect" and "material cost", compressing the material usage of the frame to the theoretical minimum while ensuring the absolute safety of the components.

[0057] In one embodiment of the present invention, in step S5, the spacing between the support columns 21 is adjusted first during iterative optimization.

[0058] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. A design optimization method for ultra-long packing racks based on stiffness matching, characterized in that: Includes the following steps: S1. Extraction of stiffness features of the packaged component A simplified beam element model of the packaged component is established. A hinged support constraint is applied at the end position where the component contacts the packaging frame. Only the self-weight load of the component is applied. The deflection curve of the component in the long axis direction is calculated. The characteristic stiffness coefficient K1 of the component is extracted based on the curve characteristics. S2. Extraction of stiffness features of the packing frame An independent finite element model of the packing frame is established. Constraints are applied at the lifting points of the frame. Only the self-weight of the frame is applied. The deflection curve of the frame along its long axis is calculated. Based on the curve features, the characteristic stiffness coefficient K2 of the frame is extracted. S3, Stiffness Matching Pre-optimization Compare the characteristic stiffness coefficients K1 and K2, and adjust the cross section of the frame load-bearing beam or the support layout, K2 > K1; S4. Construction and Analysis of Component-Frame Collaborative Model Based on the optimized parameters in step S3, a joint simulation model is established. In the contact area between the component and the frame, only nonlinear connection elements under pressure are arranged. Actual hoisting constraints and vertical loads including dynamic load coefficients are applied. The model is solved and the vertical relative displacement Δ between the component and the frame is monitored. S5. Solution Verification and Output If the vertical relative displacement Δ at the contact point is less than or equal to the preset threshold and the stress of the frame members is less than or equal to 0.9 times the material yield strength, the design is deemed qualified. If the standard is not met, return to step S3 to adjust the frame parameters until the requirements are met, and finally generate the frame construction drawings and finite element analysis report.

2. The design optimization method for ultra-long packing racks based on stiffness matching according to claim 1, characterized in that: In step S5, the preset threshold is 1.0 mm.

3. The design optimization method for ultra-long packing racks based on stiffness matching according to claim 1, characterized in that: In step S4, nonlinear connection units are used to simulate a contact state that is only under compression and not under tension, and the spacing between the nonlinear connection units is 500-800mm.

4. The design optimization method for ultra-long packing racks based on stiffness matching according to claim 1, characterized in that: In step S3, the frame characteristic stiffness coefficient K2 is 1.05 to 1.2 times the component characteristic stiffness coefficient K1.

5. The design optimization method for ultra-long packing racks based on stiffness matching according to claim 1, characterized in that: In step S5, the spacing between the support columns is adjusted first during iterative optimization.

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