Dismantling method for single-layer latticed shell structure

Abstract

The invention relates to a dismantling method for a single-layer latticed shell structure. The dismantling method comprises the following steps that the single-layer latticed shell structure is divided into a plurality of dismantling units; carrying out double-platform calculation by adopting a Matlab module and an ANSYS module to obtain an optimal dismantling path; and according to the dismantling units and the obtained optimal dismantling path, the single-layer latticed shell structure is dismantled in stages. According to the dismantling method for the single-layer latticed shell structure, a dismantling construction numerical simulation method is provided based on a life-death unit method, meanwhile, a basic node dismantling unit is defined, and a corresponding determination method is provided; on the basis of an improved simulated annealing algorithm, a single-layer latticed shell structure dismantling construction path optimization method is provided, and a process for carrying out optimization calculation on double platforms of Matlab and ANSYS is given, so that calculation steps are simplified, and calculation accuracy is also improved.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, in particular to a method for dismantling a single-layer lattice shell structure. Background Art

[0002] The demolition construction process of a single-layer lattice shell structure is a process of dismantling the structural system from complete to incomplete and then to complete demolition in stages and parts. During the construction process, the geometric shape, support conditions, load mode and size of the structure all change. Therefore, the mechanical analysis or construction verification of the structural demolition construction process must take into account the impact of these changes. According to the classification of time-varying structural mechanics, the time-varying characteristics of the structural system during the demolition construction stage of a single-layer lattice shell structure belong to the slow time-varying characteristics of jumps.

[0003] At present, the mechanical analysis tools for the demolition construction path of single-layer lattice shell structures mainly include conceptual analysis, analytical analysis and numerical simulation, and the main problems are as follows:

[0004] 1) Conceptual analysis uses the concepts of mechanics to grasp and estimate the mechanical state of the structure during the demolition process. However, this method is highly subjective and cannot guarantee the safety of the structural demolition process.

[0005] 2) Analytical analysis is an analytical method based on the principles of structural mechanics, which uses a simplified mechanical model to establish an analytical formula for mechanical response calculation. However, this method is mostly applicable to simple regular structures and cannot accurately evaluate the response of the demolition construction process of large and complex steel structures;

[0006] 3) Numerical simulation is a method that uses numerical simulation calculation methods such as the finite element method to solve the mechanical equations for structural demolition construction process response calculation and state evaluation. Among them, the more effective construction process analysis methods mainly include the state variable superposition method, the life and death unit method and the step-by-step modeling method. For simple regular symmetrical structures, the step-by-step modeling method or the state variable superposition method can be used. When the construction object is a large and complex spatial steel structure, the simulation calculation process of the above method is relatively cumbersome, and the accuracy of the calculation results cannot be guaranteed. Summary of the invention

[0007] The purpose of the present invention is to overcome the defects of the prior art and provide a method for dismantling a single-layer lattice shell structure to solve the problem that the simulation calculation process for dismantling large and complex spatial steel structures is relatively cumbersome and the calculation results are of low accuracy.

[0008] The technical solution for achieving the above-mentioned purpose is: a method for dismantling a single-layer lattice shell structure, comprising the following steps: dividing a plurality of dismantling units on the single-layer lattice shell structure; using a dual-platform calculation of a Matlab module and an ANSYS module to obtain an optimal dismantling path; and dismantling the single-layer lattice shell structure in stages according to the dismantling units and the obtained optimal dismantling path.

[0009] In a demolition method for a single-layer lattice shell structure of the present invention, a demolition construction numerical simulation method is proposed based on the birth-death unit method, and at the same time, a basic node demolition unit is defined and a corresponding determination method is proposed; based on an improved simulated annealing algorithm, a demolition construction path optimization method for a single-layer lattice shell structure is proposed, and a process for performing optimization calculations on a dual platform of Matlab and ANSYS is given, which simplifies the calculation steps and improves the calculation accuracy.

[0010] A further improvement of the method for dismantling a single-layer lattice shell structure of the present invention is that the dual-platform calculation using the Matlab module and the ANSYS module to obtain the best dismantling path includes: numbering the dismantling units and randomly generating a dismantling path array.

[0011] A further improvement of the demolition method of a single-layer lattice shell structure of the present invention is that the dual-platform calculation using the Matlab module and the ANSYS module to obtain the optimal demolition path also includes: establishing a finite element model in the ANSYS module and importing the demolition path array; performing demolition construction simulation calculation on the demolition path array to obtain the initial number of successfully demolished rods and the initial optimal demolition path.

[0012] A further improvement of the demolition method of a single-layer lattice shell structure of the present invention is that the dual-platform calculation using the Matlab module and the ANSYS module to obtain the optimal demolition path also includes: in the Matlab module, replacing the critical nodes in the initial optimal demolition path to generate an updated demolition path.

[0013] A further improvement of the demolition method of a single-layer lattice shell structure of the present invention is that, in the Matlab module, the critical nodes in the initial optimal demolition path are replaced, and the generation of an updated demolition path includes: replacing the critical nodes with subsequent nodes to obtain a first optimized demolition path array.

[0014] A further improvement of the demolition method of a single-layer lattice shell structure of the present invention is that, in the Matlab module, the critical nodes in the initial optimal demolition path are replaced, and the generation of an updated demolition path also includes: replacing the critical nodes with the demolished nodes to obtain a second optimized demolition path array.

[0015] A further improvement of the demolition method of a single-layer lattice shell structure of the present invention is that, in the Matlab module, the critical nodes in the initial optimal demolition path are replaced, and the generation of an updated demolition path also includes: in the ANSYS module, the demolition construction simulation calculation is performed on the first optimized demolition path array and the second optimized demolition path array respectively to obtain the number of rods successfully demolished by the first optimization and the number of rods successfully demolished by the second optimization.

[0016] A further improvement of the demolition method of a single-layer lattice shell structure of the present invention is that, in the Matlab module, the critical nodes in the initial optimal demolition path are replaced, and the generation of an updated demolition path also includes: comparing the first optimized number of successfully demolished rods and the second optimized number of successfully demolished rods with the initial number of successfully demolished rods, and taking the one that is greater than the initial number of successfully demolished rods as the updated demolition path.

[0017] A further improvement of the method for dismantling a single-layer lattice shell structure of the present invention is that the dual-platform calculation using the Matlab module and the ANSYS module to obtain the optimal dismantling path also includes: judging whether the updated dismantling path is within a preset error; and using the updated dismantling path that meets the preset error requirement as the optimal dismantling path.

[0018] A further improvement of the method for dismantling a single-layer lattice shell structure of the present invention is that before taking the updated dismantling path that meets the preset error requirement as the optimal dismantling path, it includes: judging whether the updated dismantling path reaches an allowed number of iterations. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a schematic flow chart of a method for dismantling a single-layer lattice shell structure.

[0020] Figure 2 It is a schematic diagram of the flow of step S120 of the present invention.

[0021] Figure 3 FIG. 4 is another flowchart diagram of step S120 of the present invention.

[0022] Figure 4 It is a schematic diagram of the flow of demolition construction simulation calculation of the present invention.

[0023] Figure 5 FIG. 4 is another flowchart diagram of step S120 of the present invention.

[0024] Figure 6 It is a flowchart diagram of step S124 of the present invention.

[0025] Figure 7 This is a schematic diagram of the first updating scheme for the demolition path of the present invention.

[0026] Figure 8 FIG. 4 is another flowchart diagram of step S124 of the present invention.

[0027] Fig. 9 It is a schematic diagram of the second updating scheme of the demolition path of the present invention.

[0028] Fig.10 FIG. 4 is another flowchart diagram of step S124 of the present invention.

[0029] Fig.11 FIG. 4 is another flowchart diagram of step S124 of the present invention.

[0030] Fig.12 FIG. 4 is another flowchart diagram of step S120 of the present invention.

[0031] Fig.13 It is a schematic diagram of the process before step S126 of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0033] See also Figure 1 , showing a schematic flow chart of a method for dismantling a single-layer lattice shell structure of the present invention. The present invention provides a method for dismantling a single-layer lattice shell structure, comprising the following steps:

[0034] Execute step S110: divide the single-layer lattice shell structure into a plurality of demolition units.

[0035] The removal unit includes a node and adjacent rods, and then step S120 is performed.

[0036] Execute step S120: use Matlab module and ANSYS module dual platform calculation to obtain the best demolition path.

[0037] Among them, the Matlab platform is used to execute the demolition path update and iterative convergence judgment of the algorithm, and the ANSYS platform is used to calculate and output the objective function value Ns under each demolition path. The calculation steps of the Matlab module and the ANSYS module dual platform are described in detail below and will not be repeated here. Then, step S130 is executed.

[0038] Execute step S130: according to the dismantling units and the obtained optimal dismantling path, dismantle the single-layer lattice shell structure in stages.

[0039] In the process of staged demolition, when the target node is demolished, all adjacent rods of the node can be divided into areas to be demolished and demolished.

[0040] See also Figure 2 , showing a schematic flow chart of step S120 of the present invention. The present invention provides a method for dismantling a single-layer lattice shell structure, step S120 comprising:

[0041] Execute step S121: number the demolition units and randomly generate a demolition path array.

[0042] Where d = {d1, d2, ..., d i-1 , d i , d i+1 , …, d n} is the demolition path array, which is regarded as the original demolition path. Node d refers to all the rods in the basic demolition unit to which the node belongs.

[0043] See also Figure 3 and Figure 4 , Figure 3 Another schematic diagram of the process of step S120 of the present invention is shown. Figure 4 The present invention provides a method for dismantling a single-layer lattice shell structure, wherein step S120 further includes:

[0044] Execute step S122: establish a finite element model in the ANSYS module and import the demolition path array.

[0045] Among them, during the finite element simulation analysis, the self-weight loads of structural members and nodes can be realized by activating and passivating the relevant units through the MEKA method.

[0046] In this embodiment, the constant load during the demolition construction process needs to be corrected. For example, in the i-th construction step, due to d i Each of the adjacent nodes of the node has an adjacent member removed, and the corresponding load dependent area is reduced. Therefore, it is necessary to correct the node load of the adjacent node according to the reduction ratio of the node dependent area.

[0047] In this embodiment, since the conventional structure has a short dismantling period and the probability of encountering a major disaster is very small, accidental loads such as earthquake effects may not be considered during the dismantling construction process.

[0048] Execute step S123: perform demolition construction simulation calculation on the demolition path array to obtain the initial number of successfully demolished rods and the initial optimal demolition path.

[0049] The demolition construction simulation calculation step also includes: starting from i=1, entering the next load step, calculating each target demolition node d i The load and the demolition unit information are used to determine d i Whether it is a support point or a bearing node; if d iIt is a support point or a support node. Return to the previous step and obtain the load and the information of the demolished unit to which it belongs for d i+1 ; if d i is not a support point or a support node, all the members within the demolished unit area to which the node d i belongs can be demolished. Corresponding to the node load of the deleted node di, and the node loads in the adjacent demolished areas are corrected. Then, perform the non-linear static analysis in the i-th load step to calculate whether it converges. If it does not converge, directly enter the post-processing module and count the number of successfully demolished members Ns(d); if it converges, calculate whether the maximum node displacement of the structure exceeds the limit; if it exceeds the limit, enter the post-processing module and count the number of successfully demolished members Ns(d); if it does not exceed the limit, continue to the next load step and obtain the load and the information of the demolished unit to which the node d i+1 belongs, and re-execute the above steps until the operation ends.

[0050] Refer to Figure 5 , which shows another flow schematic diagram of step S120 of the present invention. The present invention provides a method for demolishing a single-layer reticulated shell structure. Step S120 further includes:

[0051] Execute step S124: In the Matlab module, replace the critical nodes in the initial optimal demolition path to generate an updated demolition path.

[0052] The replacement method will be described in detail below and will not be elaborated here.

[0053] In this embodiment, it is assumed that the number of successfully demolished members corresponding to the demolition path array is Ns(d), where d i is the collapse critical point during the structure demolition process, that is, the structure collapses when the members in the demolished unit area at the i-th construction step are demolished. The simulation test results show that when some elements in the original demolition path d are replaced to generate a new demolition path d′ according to the traditional new solution generation method, when the change occurs before the demolition critical point di, there is a high probability that Ns(d′) < Ns(d); when the nodes before and after the critical point di are interchanged, the result is the same; when the change occurs after the demolition critical point di, then Ns(d′) = Ns(d), because the structure will still collapse at the critical point di under the new demolition path. It can be seen that due to the particularity of the demolition construction simulation problem, if a new solution d′ is randomly generated in the traditional way, it will make Ns(d′) less than or equal to Ns(d) with a high probability. Therefore, when applying the simulated annealing algorithm (SAA) to the optimization calculation of the demolition construction path of a rigid space grid structure, it is necessary to improve the SAA algorithm to a certain extent, and an improved simulated annealing algorithm (ISAA) for the optimization of the demolition construction path of a space steel structure is proposed.

[0054] Refer to Figure 6 and Figure 7 , Figure 6 The schematic diagram of the process of step S124 of the present invention is shown. Figure 7 The present invention provides a method for dismantling a single-layer lattice shell structure, wherein step S124 comprises:

[0055] Execute step S1241: replace the critical node with the subsequent node to obtain a first optimized demolition path array.

[0056] Among them, replacing the critical node with the subsequent node is used as the first updating scheme, and the subsequent node is the node other than the critical node and the removed node.

[0057] In this implementation, in order to find an optimized removal path, it is necessary to traverse and permute subsequent nodes for screening.

[0058] See also Figure 8 and Fig. 9 , Figure 8 is another flow chart of step S124 of the present invention, Fig. 9 The present invention provides a method for dismantling a single-layer lattice shell structure, wherein step S124 further includes:

[0059] Execute step S1242: replace the critical nodes with the removed nodes to obtain a second optimized removal path array.

[0060] Among them, replacing the critical nodes with the removed nodes is used as the second update scheme, and it is necessary to traverse and replace the removed nodes for screening.

[0061] See also Fig.10 , showing another flow chart of step S124 of the present invention. The present invention provides a method for dismantling a single-layer lattice shell structure, step S124 further comprising:

[0062] Execute step S1243: In the ANSYS module, perform demolition construction simulation calculations on the first optimized demolition path array and the second optimized demolition path array respectively to obtain the number of rods successfully demolished by the first optimization and the number of rods successfully demolished by the second optimization.

[0063] Among them, the demolition construction simulation calculation of the first optimized demolition path array and the second optimized demolition path array needs to respectively execute the steps of the demolition construction simulation calculation in the above text to obtain the number of successfully demolished rods in the first optimization and the number of successfully demolished rods in the second optimization.

[0064] See also Fig.11 , showing another flow chart of step S124 of the present invention. The present invention provides a method for dismantling a single-layer lattice shell structure, step S124 further comprising:

[0065] Execute step S1244: Compare the number of successfully removed members in the first optimized solution and the second optimized solution with the number of initially successfully removed members respectively, and use the one with a number greater than the initially successfully removed members as the updated removal path.

[0066] Among them, considering the number of successfully removed members on the basis of selecting the path with more removed nodes can more accurately compare better removal paths.

[0067] In this embodiment, according to the characteristics of the demolition construction problem itself, using the basic node demolition unit determination method proposed above, the acceptance probability of each path update scheme can be expressed by the following formula:

[0068]

[0069] In the formula, d = {d1, d2,..., d i-1 , d i , d i+1 ,..., d n} is the original removal path; the node d refers to all the members within the basic demolition unit to which the node belongs, Ns(d) is the number of successfully removed members corresponding to the original removal path; K is the coefficient of variation; er is the allowable error between the current solution and the target solution; n is the total number of members in the structure.

[0070] In this embodiment, for the first update scheme, since the change in the demolition order occurs between the critical point and subsequent nodes, the number of successfully removed members Ns(d′) corresponding to the updated removal path will not be less than Ns(d). Therefore, this scheme can be regarded as an updated scheme of a better solution.

[0071] In the second update scheme, the updated removal path will correspond to two results. One is that Ns(d′) < Ns(d) occurs because the previously passed removal path before the critical point d i is damaged. The numerical simulation results show that this situation will大概率 occur. The other is that since the replacement of the node to be removed in the original removal path will result in a more unfavorable internal force distribution and a weakening of the structural stiffness and bearing capacity, and the updated removal path exactly avoids the removal of this node, so Ns(d′) ≥ Ns(d). Since the probability of the second situation is lower, ignoring this demolition result, Ns(d′) will be less than Ns(d). Therefore, the second update scheme can be regarded as an updated scheme of an inferior solution. Combining the generation probabilities of each update scheme defined by the formula, the above improved removal path update scheme can be regarded as the presentation and application of the Metropolis criterion in the generation method of new solutions.

[0072] Refer to Fig.12, showing another flow chart of step S120 of the present invention. The present invention provides a method for dismantling a single-layer lattice shell structure, step S120 further comprising:

[0073] Execute step S125: determine whether the updated removal path is within a preset error.

[0074] Among them, the default error is determined by judging whether Ns(d)≥e r *n Whether it is true.

[0075] In this embodiment, e r is the allowable error between the current solution and the target solution, and n is the total number of structural members. It is a specific value set artificially in actual construction and is not specifically limited here.

[0076] Execute step S126: take the updated demolition path that meets the preset error requirement as the optimal demolition path.

[0077] Among them, the updated demolition path that meets the number of demolished rods is taken as the optimal demolition path.

[0078] See also Fig.13 , showing a schematic diagram of the process before step S126 of the present invention. The present invention provides a method for dismantling a single-layer lattice shell structure, which includes before step S126:

[0079] Execute step S1251: determine whether the update and removal path reaches the allowed number of iterations.

[0080] Among them, the further check of the number of iterations is to determine whether all the nodes in the single-layer lattice shell structure have been traversed once to meet the demolition requirements.

[0081] The present invention is described in detail above in conjunction with the embodiments of the drawings. A person skilled in the art can make various changes to the present invention according to the above description. Therefore, certain details in the embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention shall be the scope defined by the attached claims.

Claims

1. A method for dismantling a single-layer lattice shell structure, characterized in that: The steps include: Divide a single-layer lattice shell structure into multiple demolition units; The optimal demolition path is obtained by using Matlab module and ANSYS module dual platform calculation; The single-layer lattice shell structure is dismantled in stages according to the dismantling unit and the obtained optimal dismantling path.

2. The method for dismantling a single-layer lattice shell structure according to claim 1, characterized in that: The optimal demolition path obtained by using the Matlab module and ANSYS module dual platform calculation includes: The demolition units are numbered and a demolition path array is randomly generated.

3. The method for dismantling a single-layer lattice shell structure according to claim 2, characterized in that: The dual-platform calculation using Matlab module and ANSYS module to obtain the optimal demolition path also includes: Establishing a finite element model in the ANSYS module and importing the demolition path array; A demolition construction simulation calculation is performed on the demolition path array to obtain the initial number of successfully demolished rods and the initial optimal demolition path.

4. The method for dismantling a single-layer lattice shell structure according to claim 3, characterized in that: The dual-platform calculation using Matlab module and ANSYS module to obtain the optimal demolition path also includes: In the Matlab module, the critical nodes in the initial optimal demolition path are replaced to generate an updated demolition path.

5. The method for dismantling a single-layer lattice shell structure according to claim 4, characterized in that: In the Matlab module, replacing the critical nodes in the initial optimal removal path to generate an updated removal path includes: Replace the critical nodes with the subsequent nodes to obtain the first optimized demolition path array.

6. The method for dismantling a single-layer lattice shell structure according to claim 5, characterized in that: In the Matlab module, replacing the critical nodes in the initial optimal removal path to generate an updated removal path further comprises: Replace the critical nodes with the removed nodes to obtain a second optimized removal path array.

7. The method for dismantling a single-layer lattice shell structure according to claim 6, characterized in that: In the Matlab module, replacing the critical nodes in the initial optimal removal path to generate an updated removal path further comprises: In the ANSYS module, demolition construction simulation calculations are performed on the first optimized demolition path array and the second optimized demolition path array respectively to obtain the number of rods successfully demolished by the first optimization and the number of rods successfully demolished by the second optimization.

8. The method for dismantling a single-layer lattice shell structure according to claim 7, characterized in that: In the Matlab module, replacing the critical nodes in the initial optimal removal path to generate an updated removal path further comprises: The first optimized number of successfully removed rods and the second optimized number of successfully removed rods are compared with the initial number of successfully removed rods, and the one that is greater than the initial number of successfully removed rods is used as the updated removal path.

9. The method for dismantling a single-layer lattice shell structure according to claim 8, characterized in that: The dual-platform calculation using Matlab module and ANSYS module to obtain the optimal demolition path also includes: Determining whether the updated removal path is within a preset error; The updated demolition path that meets the preset error requirement is used as the optimal demolition path.

10. The method for dismantling a single-layer lattice shell structure according to claim 9, characterized in that: The step of using the updated removal path that meets the preset error requirement as the optimal removal path includes: Determine whether the update and removal path reaches the allowed number of iterations.

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