A safety calculation method for attached aluminum alloy lifting platform

Abstract

The present invention discloses a safety calculation method for an attached aluminum alloy lifting platform, which simplifies the guide rails, vertical poles, diagonal rods, supporting trusses, etc. of the aluminum alloy platform into beam units, and simplifies the scaffolding into shell unit modeling, and first performs an overall check. Then, a three-dimensional model modeling analysis is performed on the wall-attached supports, which can greatly reduce the number of calculation grids, thereby reducing calculation time and memory. Beam units are suitable for slender structures in which one dimension is much larger than the other two dimensions, and only one-dimensional axes need to be considered in finite element modeling; shell units are suitable for structures in which dimensions in two directions are much larger than another dimension, and are considered as two-dimensional planes in finite element modeling. The present invention models part of the beam structure of the main frame of the aluminum alloy platform as a beam model in the finite element software, converts the load and adds it to the corresponding boundary, first performs an overall check, and then performs a three-dimensional model modeling analysis on the wall-attached supports, which can greatly reduce the amount of calculation and is also in line with actual conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of construction engineering, and in particular to a safety verification method for an attached aluminum alloy lifting platform. Background Art

[0002] As my country continues to promote high-quality economic development, the modern construction industry is moving towards automation, intelligence, and prefabrication. Aluminum alloy attached lifting safety protection platforms are structures that are erected at a certain height and attached to the building structure. Relying on their own lifting equipment and devices, they can climb or descend floor by floor with the building structure. They feature safety protection, anti-tilt, anti-fall, and synchronous lifting functions. However, the development of aluminum alloy platform equipment is difficult, primarily due to its complex structure and complex stress conditions. It bears impact, alternating, and multi-directional loads, making them difficult to master. Excessive stress can cause material failure and lead to safety accidents.

[0003] The traditional safety verification method for attached lifting platforms mainly starts from the combined deformation theory formula of beams in material mechanics. Through external loads and boundary conditions, the bending moment and stress of the beam are calculated, and then the maximum normal stress is calculated and compared with the allowable stress. However, this method is relatively simplified and does not take into account the precise geometric structure and load distribution, nor can it obtain accurate stress distribution. At the same time, the traditional attached lifting platform is an all-steel structure, and the safety verification method is not suitable for aluminum alloy platforms. The overall structure of the aluminum alloy platform is complex. If an overall three-dimensional model is established for full solid simulation analysis, the number of grids will be huge, the required solution memory will be too large, and the solution time will be long. Summary of the Invention

[0004] The purpose of the present invention is to provide a safety verification method for an attached aluminum alloy lifting platform, to invent a simple and fast safety verification method for this aluminum alloy attached protective platform, and to support its safety in use.

[0005] The technical solution adopted in the present invention is:

[0006] A safety calculation method for an attached aluminum alloy lifting platform comprises the following steps:

[0007] Step 1: Establish a frame model based on the aluminum alloy protection platform structure.

[0008] Step 2: Obtain the cross-sectional parameters and material parameters of the components of the aluminum alloy protection platform structure and establish displacement boundary conditions;

[0009] Step 3: Obtain body load, construction load and wind load and use them as load input to perform stress verification of the frame;

[0010] Step 4: Mesh the frame model, calculate the maximum Mises stress of the beam and shell elements of the frame model, and convert the force applied by the frame model to the wall support. The solution method uses the structural mechanics module and the quadratic Lagrangian element.

[0011] Step 5: Construct a wall-mounted support model, apply the force applied by the frame model to the wall-mounted support on the corresponding surface of the wall-mounted support, and perform finite element calculation on the wall-mounted support under the applied force state to extract the maximum stress. The Mises stress calculation formula of the wall-mounted support is:

[0012]

[0013] Among them, σ1, σ2, and σ3 are the first, second, and third principal stresses respectively.

[0014] Specifically, principal stresses are the normal stresses at a point on the three principal planes. They can be sorted by magnitude into first, second, and third principal stresses. σ1 represents the largest principal stress, σ2 represents the intermediate principal stress, and σ3 represents the smallest principal stress. σ1 ≥ σ2 ≥ σ3. The ordering must be based on positive and negative signs, not absolute values. Tensile stress is positive, and compressive stress is negative.

[0015] Step 6: Using the strength condition σ m,max ≤[σ] Strength check is performed on beam elements, shell elements and wall supports respectively, where σ m,max To calculate the maximum stress of the target to be checked, [σ] is the allowable stress of the material used for the target to be checked;

[0016] Specifically, σ m,max Refers to the maximum Mises stress during the process of verifying the target loading force. After obtaining the Mises stress of the entire structure using the above calculation formula, the post-processing module of the finite element software can calculate the maximum stress value and the area where it is located.

[0017] Step 7: Determine whether the maximum stress of all grids of the frame model is less than the corresponding allowable stress; if so, determine that the aluminum alloy protection platform structure meets the strength requirements; otherwise, determine that the aluminum alloy protection platform structure is insufficient in strength.

[0018] Furthermore, in step 1, the guide rails, uprights, diagonal braces, and supporting trusses are simplified into beam elements, and the scaffolding boards are simplified into shell elements.

[0019] Furthermore, in step 3, the deadweight of the aluminum alloy protection platform structure is applied to the entire structure as a body load.

[0020] Furthermore, in step 3, the construction load is obtained based on the corresponding industry standard and applied to the upper surface of the corresponding unit.

[0021] Furthermore, the calculation formula for wind load in step 3 is as follows:

[0022] ω k =μ Z μ S ·ω0

[0023] Where: ω k ——Standard value of wind load, in kilonewtons per square meter (kN / m 2 ); μ Z — Wind pressure height variation coefficient, which is determined according to the maximum climbing height of the protective platform and the provisions of GB50009; μ S ——wind load body coefficient of the protection platform; ω0——basic wind pressure value, unit is kilonewton per square meter (kN / m 2 ), based on the set recurrence period, take the corresponding wind pressure value according to the provisions of GB50009.

[0024] Furthermore, the value of the recurrence period n is 10.

[0025] Furthermore, in step 3, the wind load is loaded on the entire frame after conversion. Specifically, the conversion is to substitute μ Z、 μ S、 The value of ω0 in the wind load calculation formula is taken in accordance with relevant national regulations. After the calculation result is obtained, it is input into the calculation software comsol as the force loaded on the protection platform and loaded on the entire frame.

[0026] Specifically, as a feasible embodiment, the standard value of wind load is The windward area is 84m 2 , the total force is 60.14kN, evenly loaded on the vertical pole.

[0027] Furthermore, in step 5, the connection between the wall-attached support in the aluminum alloy protective platform structure is regarded as a fixed end constraint, and fixed boundary conditions with zero displacement in the x, y, and z directions are applied at the corresponding positions; the connection between the lifting support and the guide rail is set as a boundary condition with zero displacement in the x and y directions.

[0028] Furthermore, in step 6, the allowable stress of the aluminum alloy material is 200 MPa, and the allowable stress of the steel material is 200 MPa.

[0029] Furthermore, the frame model is imported into the corresponding numerical simulation software to perform safety verification on the attached aluminum alloy lifting platform.

[0030] The present invention adopts the above technical solution, simplifying the aluminum alloy platform's guide rails, uprights, diagonal braces, and supporting trusses into beam elements, and the scaffolding into shell element modeling, which is first verified as a whole. Three-dimensional modeling and analysis of the wall-mounted supports can significantly reduce the number of computational grids, thereby reducing computation time and memory. Beam elements are suitable for slender structures where one dimension is significantly larger than the other two, and only one axis needs to be considered in finite element modeling. Shell elements are suitable for structures where two dimensions are significantly larger than the other, and are considered as two-dimensional planes in finite element modeling.

[0031] This invention fills a gap in the rapid verification method for aluminum alloy attached lifting safety platforms. Compared to a complete three-dimensional finite element model, the simplified modeling method employed requires fewer elements and requires less computation, offering the advantages of speed and simplicity. Furthermore, the methods and theories employed are easily applicable and understandable to engineers, offering a degree of versatility and suitability for calculations of similar structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments;

[0033] Figure 1 This is a flow chart of a safety calculation method for an attached aluminum alloy lifting platform according to the present invention;

[0034] Figure 2 This is a structural schematic diagram of an attached aluminum alloy lifting platform of the present invention;

[0035] Figure 3 This is a schematic diagram of a three-dimensional model of an attached aluminum alloy lifting platform according to the present invention;

[0036] Figure 4 This is the simplified beam-shell model of the attached aluminum alloy lifting platform of the present invention.

[0037] Figure 5 A schematic diagram of the structure of the frame model of the present invention divided into finite element grids;

[0038] Figure 6 Schematic diagram of the stress calculation results of the beam unit of the present invention;

[0039] Figure 7 Schematic diagram of the stress calculation results of the shell element of the present invention;

[0040] Figure 8 This is a schematic diagram of a finite element three-dimensional model of the wall-mounted support of the attached aluminum alloy lifting platform of the present invention;

[0041] Figure 9 It is a schematic diagram of the stress calculation results of the wall-attached support of the present invention. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0043] Aluminum alloy attached lifting safety protection platforms utilize a large amount of aluminum alloy, resulting in complex stress conditions. Furthermore, the mechanical properties of aluminum alloy differ significantly from those of steel. However, little research has focused on this type of platform. This present invention addresses the gap in rapid verification methods for aluminum alloy attached lifting safety protection platforms. Compared to a complete three-dimensional finite element model, the simplified modeling method employed has fewer elements and requires less computation, offering the advantages of speed and simplicity. Furthermore, the methods and theories employed are convenient for engineering personnel to apply and understand, possess a certain degree of versatility, and are applicable to calculations of similar structures.

[0044] like Figures 1 to 9 As shown in FIG1 , the present invention discloses a safety calculation method for an attached aluminum alloy lifting platform, which comprises the following steps:

[0045] Step 1, such as Figure 3 As shown, a frame model is established based on the aluminum alloy protection platform structure.

[0046] Specifically, if Figure 4 As shown, the guide rails, vertical poles, diagonal braces, and supporting trusses are simplified into beam elements, and the scaffolding is simplified into shell elements. The simplified model can be imported into the numerical simulation software COMSOL;

[0047] Step 2: Obtain the cross-sectional parameters and material parameters of the components of the aluminum alloy protection platform structure and establish displacement boundary conditions;

[0048] Specifically, the parameters are shown in Tables 1 and 2. Rigid connecting components, such as horizontal trusses and internal and external vertical pole connecting braces, are made of steel. In the vertical main frame of the protective platform, the guide rails are made of aluminum alloy profiles, the external vertical poles are made of aluminum alloy square tubes, and the Z-braces and bottom crossbars are made of steel. In the horizontal support structure, the bottom scaffolding and working floor feet are welded aluminum alloy profiles, the internal vertical poles are made of aluminum alloy square tubes, and the rest are made of steel.

[0049]

[0050] Table 1 Cross-sectional parameters of attached aluminum alloy lifting platform

[0051]

[0052] Table 2 Material parameters of attached aluminum alloy lifting platform

[0053] Displacement boundary conditions are used during finite element analysis to set the displacement of certain boundaries to zero, as they are necessary to prevent convergence. In this example, the connection between the wall support and the wall can be considered a fixed constraint, with fixed boundary conditions of zero displacement in the x, y, and z directions applied at the corresponding locations. At the connection between the lift support and the guide rail, the guide rail can only move up and down, so boundary conditions of zero displacement in the x and y directions are applied.

[0054] Step 3: Obtain body load, construction load and wind load and use them as load input to perform stress verification of the frame;

[0055] Specifically, the finite element method requires the selection of load conditions. In this example, the structural mechanics module of COMSOL is used. The body load, construction load, and wind load are converted according to the actual stress conditions and applied to the corresponding boundaries.

[0056] Furthermore, in step 3, the deadweight of the aluminum alloy protection platform structure is applied to the entire structure as a body load.

[0057] Furthermore, in step 3, the construction load is obtained based on the corresponding industry standard and applied to the upper surface of the corresponding unit.

[0058] Specifically, the construction load is based on the People's Republic of China Construction Industry Standard "Safety Protection Platform for Attached Lifting Operations in Construction" (JG / T 546-2019), with a maximum value of 3kN / m 2 , applied on the upper surface of the scaffolding board.

[0059] Furthermore, the calculation formula for wind load in step 3 is as follows:

[0060] ω k =μ Z μ S ·ω0

[0061] Where: ω k ——Standard value of wind load, in kilonewtons per square meter (kN / m 2 ); μ Z — Wind pressure height variation coefficient, which is determined according to the maximum climbing height of the protective platform and the provisions of GB50009; μ S ——wind load body coefficient of the protection platform; ω0——basic wind pressure value, unit is kilonewton per square meter (kN / m 2 ), based on the set return period, the corresponding wind pressure value is obtained according to the provisions of GB50009. As a feasible implementation method, the return period n is set to 10.

[0062] Furthermore, in step 3, the wind load is loaded on the entire frame after conversion.

[0063] Specifically, the conversion is to substitute μ Z、 μ S、 The value of ω0 in the wind load calculation formula is determined in accordance with relevant national regulations. After the calculation result is obtained, it is used as the force loaded on the protection platform and input into the calculation software COMSOL to load it on the entire frame. As a feasible embodiment, the standard value of wind load is The windward area is 84m 2 , the total force is 60.14kN, evenly loaded on the vertical pole.

[0064] Step 4, such as Figure 5 As shown, the frame model is meshed, and the maximum Mises stress of the beam element and shell element of the frame model are calculated respectively, and the force applied by the frame model to the wall support is converted;

[0065] Specifically, the solution can be performed using the structural mechanics module and quadratic Lagrangian elements within the relevant data simulation software for stress calculation. To use the software, navigate to Solid Mechanics in the Model Builder of COMSOL software and select Quadratic Lagrangian elements from the Displacement Field list in the Solid Mechanics settings. The software will automatically solve the constitutive equations for elasticity.

[0066] Furthermore, considering the plasticity of aluminum alloy, the fourth strength theory is used for verification to calculate the maximum Mises stress. The Mises stress calculation formula is:

[0067]

[0068] Here, σ1, σ2, and σ3 are the first, second, and third principal stresses, respectively. Principal stresses are the normal stresses at a point on the three principal planes. They are sorted by magnitude into the first, second, and third principal stresses. σ1 represents the largest principal stress, σ2 represents the intermediate principal stress, and σ3 represents the smallest principal stress. σ1 ≥ σ2 ≥ σ3. The ordering must be based on positive and negative signs, not absolute values. Tensile stress is positive, and compressive stress is negative.

[0069] As a feasible implementation, the present invention can obtain the maximum stress of the structure through simulation results of numerical simulation software.

[0070] like Figure 6 As shown in the figure, the stress calculation results of the vertical pole, guide rail and connecting support structure using the beam unit model are shown in the figure. Figure 6 As can be seen from the figure, the areas with greater stress are the area between the top and second floors, as well as the truss support structure at the bottom. The calculated maximum stress is 125.5 MPa, which is less than the allowable stress.

[0071] Specifically, as shown in Figure 7, the stress calculation results of the scaffolding board using the shell element model are shown. The areas with higher stress are the middle part of the scaffolding board and some edges. The maximum stress is 26.2 MPa, which is less than the allowable stress.

[0072] Step 5: Construct a wall-mounted support model, apply the force applied by the frame model to the wall-mounted support on the corresponding surface of the wall-mounted support, and perform finite element calculation on the wall-mounted support under the applied force state to extract the maximum stress. The Mises stress calculation formula of the wall-mounted support is:

[0073]

[0074] Here, σ1, σ2, and σ3 are the first, second, and third principal stresses, respectively. Principal stresses are the normal stresses at a point on the three principal planes. They are sorted by magnitude into the first, second, and third principal stresses. σ1 represents the largest principal stress, σ2 represents the intermediate principal stress, and σ3 represents the smallest principal stress. σ1 ≥ σ2 ≥ σ3. The ordering must be based on positive and negative signs, not absolute values. Tensile stress is positive, and compressive stress is negative.

[0075] Specifically, if Figure 8 The three-dimensional model of the wall-attached support shown in the figure extracts the force applied by the frame to the wall-attached support from the calculation results, and the total force is applied to the corresponding surface; the boundary conditions are set to zero displacement in the x, y, and z directions at the fixed position; that is, the connection of the wall-attached support in the aluminum alloy protective platform structure is regarded as a fixed end constraint, and a fixed boundary condition of zero displacement in the x, y, and z directions is applied at the corresponding position; the connection between the lifting support and the guide rail is set to a boundary condition of zero displacement in the x and y directions.

[0076] The maximum stress is extracted by finite element calculation of the wall support. m,max ≤[σ] for strength check, the Mises stress calculation formula of the wall support is: Among them, σ1, σ2, and σ3 are the first, second, and third principal stresses respectively. Figure 9 As shown in the figure, the calculated maximum stress is 5.2 MPa, which is less than the allowable stress of the material.

[0077] Step 6: Using the strength condition σ m,max ≤[σ] Strength check is performed on beam elements, shell elements and wall supports respectively, where σ m,max To calculate the maximum stress of the target to be checked, [σ] is the allowable stress of the material used for the target to be checked;

[0078] Furthermore, in step 6, the allowable stress of the aluminum alloy material is 200 MPa, and the allowable stress of the steel material is 200 MPa.

[0079] Step 7: Determine whether the maximum stress of all grids of the frame model is less than the corresponding allowable stress; if so, determine that the aluminum alloy protection platform structure meets the strength requirements; otherwise, determine that the aluminum alloy protection platform structure is insufficient in strength.

[0080] Furthermore, the frame model is imported into the corresponding numerical simulation software to perform safety verification on the attached aluminum alloy lifting platform.

[0081] Specifically, the overall analysis process can use different numerical simulation software to perform similar analysis, such as using ANSYS and Abaqus instead of COMSOL for mechanical simulation, and the calculation process can also use different programming software for similar solutions.

[0082] The present invention adopts the above technical solution to simplify the guide rails, vertical poles, diagonal braces, supporting trusses, etc. of the aluminum alloy platform into beam units, and simplifies the scaffolding into shell unit modeling, and first performs an overall verification. Then, a three-dimensional model modeling analysis is performed on the wall-attached supports, which can greatly reduce the number of calculation grids, thereby reducing calculation time and memory. Beam units are suitable for slender structures in which one dimension is much larger than the other two dimensions, and only one-dimensional axes need to be considered in finite element modeling; shell units are suitable for structures in which two dimensions are much larger than another dimension, and are considered as two-dimensional planes in finite element modeling. The present invention uses numerical simulation methods to provide a more scientific method for the verification of such a platform. The present invention models part of the beam structure of the main frame of the aluminum alloy platform as a beam model in the finite element software, converts the load and adds it to the corresponding boundary, first performs an overall verification, and then performs a three-dimensional model modeling analysis on the wall-attached supports, which can greatly reduce the amount of calculation and is also in line with actual conditions.

[0083] This invention fills a gap in the rapid verification method for aluminum alloy attached lifting safety platforms. Compared to a complete three-dimensional finite element model, the simplified modeling method employed requires fewer elements and requires less computation, offering the advantages of speed and simplicity. Furthermore, the methods and theories employed are easily applicable and understandable to engineers, offering a degree of versatility and suitability for calculations of similar structures.

[0084] Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present application is not intended to limit the scope of the application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

Claims

1. A safety calculation method for an attached aluminum alloy lifting platform, characterized by: It includes the following steps: Step 1: Establish a frame model based on the aluminum alloy protection platform structure, simplify the guide rails, vertical poles, diagonal rods, and supporting trusses into beam elements, and simplify the scaffolding into shell elements; Step 2: Obtain the cross-sectional parameters and material parameters of the components of the aluminum alloy protection platform structure and establish displacement boundary conditions; Step 3: Obtain body load, construction load and wind load and use them as load input to perform stress verification of the frame; Step 4: Mesh the frame model, calculate the maximum Mises stress of the beam element and shell element of the frame model, and convert the force applied by the frame model to the wall support; Step 5: Construct a wall-mounted support model, apply the force applied by the frame model to the wall-mounted support on the corresponding surface of the wall-mounted support, and perform finite element calculation on the wall-mounted support under the applied force state to extract the maximum stress. The Mises stress calculation formula of the wall-mounted support is: Among them, the principal stress is the normal stress of a point on the three principal planes, which is divided into the first, second and third principal stresses according to the order of magnitude; σ1, σ2, σ3 are the first, second and third principal stresses respectively; Step 6: Using the strength condition σ m,max ≤[σ] Strength check is performed on beam elements, shell elements and wall supports respectively, where σ m,max To calculate the maximum stress of the target to be checked, [σ] is the allowable stress of the material used for the target to be checked; Step 7: Determine whether the maximum stress of all grids of the frame model is less than the corresponding allowable stress; if so, determine that the aluminum alloy protection platform structure meets the strength requirements; otherwise, determine that the aluminum alloy protection platform structure is insufficient in strength.

2. A safety calculation method for an attached aluminum alloy lifting platform according to claim 1, characterized in that: In step 3, the deadweight of the aluminum alloy protection platform structure is applied to the entire structure as the body load; the construction load is obtained based on the corresponding industry standards and applied to the upper surface of the corresponding unit.

3. The safety calculation method for an attached aluminum alloy lifting platform according to claim 1, characterized in that: The calculation formula for wind load in step 3 is as follows: oh k =μ Z ·m S ·ω0 Where: ω k ——standard value of wind load, in kilonewtons per square meter; μ Z — Wind pressure height variation coefficient, which is determined according to the maximum climbing height of the protective platform and the provisions of GB50009; μ S ——Wind load shape coefficient of the protection platform; ω0——Basic wind pressure value, the unit is kilonewton per square meter, based on the set recurrence period, the corresponding wind pressure value is taken according to the provisions of GB50009.

4. The safety calculation method for an attached aluminum alloy lifting platform according to claim 3, characterized in that: The return period n is set to 10.

5. The safety calculation method for an attached aluminum alloy lifting platform according to claim 1, characterized in that: In step 3, the wind load is converted and loaded on the entire frame.

6. The safety calculation method for an attached aluminum alloy lifting platform according to claim 1, characterized in that: In step 5, the connection between the wall-attached support in the aluminum alloy protective platform structure is regarded as a fixed end constraint, and fixed boundary conditions with zero displacement in the x, y, and z directions are applied at the corresponding positions; the connection between the lifting support and the guide rail is set as a boundary condition with zero displacement in the x and y directions.

7. The safety calculation method for an attached aluminum alloy lifting platform according to claim 1, characterized in that: Import the frame model into the corresponding numerical simulation software to perform safety verification on the attached aluminum alloy lifting platform.

Images