Simulation and optimization construction method for early-dismantling construction of formwork support system

Abstract

The invention relates to the technical field of building construction, in particular to a formwork support system early-dismantling construction simulation optimization construction method, which accurately simulates the early-dismantling construction process of a construction site formwork support system based on a numerical analysis method by constructing a formwork support system early-dismantling construction safety evaluation and economic evaluation index system. The early-dismantling construction simulation optimization method has the remarkable advantages of being low in cost, short in period, repeatable and the like, and the early-dismantling construction scheme is evaluated and optimized, so that the optimal early-dismantling scheme capable of giving consideration to early-dismantling construction safety and economical efficiency is obtained, and early-dismantling construction is carried out. And the method is of great significance to popularization and application of the early-dismantling construction technology of the formwork support system.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, in particular to a method for simulating and optimizing the early dismantling construction of a formwork support system. Background Art

[0002] Current building structures are gradually developing towards high-rise and large-span directions, and the difficulty of construction has increased significantly; at this stage, cast-in-place concrete structures still occupy a dominant position in building structures, and the number of formwork supports required for construction is very large.

[0003] In the traditional construction process, it is generally necessary to uniformly dismantle the entire formwork support system after the concrete reaches the design strength. This means that during the entire period from the erection to the dismantling of the formwork support, all frame components cannot be effectively reused, resulting in high construction costs for cast-in-place concrete projects. The early dismantling construction of the formwork support system can dismantle part of the frame structure in advance before the concrete fully reaches the design strength, thereby significantly improving the use efficiency and turnover speed of the frame components and effectively reducing construction costs; however, premature dismantling of some frame components may cause the formwork support to overload or even become unstable and collapse, posing a serious safety hazard.

[0004] Therefore, how to accurately evaluate the safety and economy of the early-removal formwork support system and find the optimal solution to balance the structural safety and construction cost of the early-removal formwork support system is a key issue that needs to be studied and solved urgently in the construction of cast-in-place concrete projects. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a method for simulating and optimizing the early dismantling construction of a formwork support system.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A method for simulating and optimizing the early dismantling construction of a formwork support system, comprising:

[0008] S1. Conduct numerical simulation on the construction process of the non-early dismantling formwork support system, and determine the dismantling position and order of the support rods in the non-early dismantling formwork support system based on the numerical simulation results to obtain a preliminary early dismantling plan;

[0009] S2. Construct a safety evaluation index system for the formwork frame including the stress, strain, node bending moment, vertical displacement, horizontal displacement and frame load parameters, as well as an economic evaluation index system including early dismantling construction to save material costs, labor costs and indirect costs;

[0010] S3. According to the preliminary early dismantling scheme, numerical simulation of the early dismantling construction process is carried out for the non-early dismantling formwork support system, and the preliminary early dismantling scheme is evaluated based on the safety evaluation index system and the economic evaluation index system using the numerical simulation results;

[0011] S4. If the evaluation result does not meet the predetermined requirements, adjust the dismantling position and order of the support rods, propose a new preliminary early dismantling plan and return to execute S3; if the evaluation result meets the predetermined requirements, use the current preliminary early dismantling plan as the final early dismantling plan that is safe, reasonable and economical, and carry out the early dismantling construction.

[0012] Preferably, a further technical solution of the present invention is:

[0013] Preferably, the specific process of obtaining the preliminary early removal plan in S1 includes:

[0014] According to the original construction design of the non-early-removal formwork support system, the early-age strength of concrete is evaluated, and then a numerical simulation model of the non-early-removal formwork support system is established that is consistent with the geometric dimensions, constraints and construction loads of the actual engineering formwork support system;

[0015] Numerical simulation is carried out based on the numerical simulation model, and the stress and deformation information of the formwork frame is extracted from the simulation results. The removal position and order of the support rods with stress and deformation less than the set conditions are determined to obtain a preliminary early removal plan.

[0016] Preferably, the process of evaluating the early age strength of concrete includes:

[0017] Evaluation of early age compressive strength of concrete:

[0018] ;

[0019] in, for Compressive strength of concrete at day age; is the compressive strength of concrete at 28 days of age;

[0020] Evaluation of the elastic modulus of concrete at early age:

[0021] .

[0022] Preferably, the template frame safety evaluation index system is expressed as follows:

[0023] ;

[0024] Where S represents the critical load factor, σ c represents the stress of the frame, ε c represents the strain of the frame, m crepresents the node bending moment of the frame, v c represents the vertical displacement of the frame, h c represents the horizontal displacement of the frame, p c represents the load parameter of the frame, σ f represents the allowable stress of the frame, ε f represents the allowable strain of the frame, m f represents the allowable node bending moment of the frame, v f It represents the allowable vertical displacement of the frame, h f represents the allowable horizontal displacement of the frame, p f represents the allowable load parameter of the frame, k σ , k ε , k m , k v , k h and k p They are stress, strain, node bending moment, vertical displacement, horizontal displacement and safety multiplier of load parameter.

[0025] Preferably, the economic evaluation index system is expressed as follows:

[0026] ;

[0027] Among them, C total In order to save the total construction cost, C m-s In order to save material costs, C l-s In order to save labor costs, C i-s To save indirect costs;

[0028] ;

[0029] Among them, a is the template area required for the project, Q a is the daily rental fee of the template per unit area, b is the volume of the support rod corresponding to the template, Q b is the rental fee per unit support rod per day, D t D is the number of days the formwork and support rods are used under the non-early removal construction plan, e The number of days the formwork and support rods are used under the preliminary early removal plan;

[0030] ;

[0031] Among them, H t H is the working hours required for the formwork engineering under the non-early removal construction plan, e is the working hours required for the formwork project under the preliminary early removal plan, n is the number of workers participating in the construction at the same time, Q l The labor cost for each worker per working hour;

[0032] ;

[0033] Among them, T i T is the time required for the formwork support system from construction to dismantling under the non-early dismantling construction plan. j The time required for the formwork support system from construction to dismantling under the initial early dismantling plan, Q m The daily rental fee for the equipment is n Daily management fee for the project.

[0034] Preferably, the numerical simulation process in S3 includes:

[0035] Step 1: Create a frame model:

[0036] According to the geometric dimensions of the actual formwork support system at the construction site, the actual original non-early dismantling frame model is established, and the formwork support early dismantling model is obtained according to the preliminary early dismantling plan;

[0037] Step 2: Set the node connection method:

[0038] The semi-rigid node connection method is used between the vertical rod and the horizontal rod in the support rod, and the hinge node connection method is used between the vertical rod and the diagonal rod. The friction at the hinge is negligible, so the diagonal rod is only subjected to axial force, thereby accurately simulating the mechanical behavior of the nodes in the formwork support system;

[0039] Step 3: Set boundary conditions:

[0040] The displacement freedom of the bottom of the pole is set, and a vertical downward construction load is applied to the top of the pole, so as to be consistent with the actual construction process;

[0041] Step 4: Loading process simulation:

[0042] The formwork support early dismantling model is numerically discretized, and a linear buckling analysis is performed based on the mechanical properties of the support rod material to obtain the various instability modes of the support rod. Then, the initial defect is introduced according to the lowest instability mode, and the nonlinear post-buckling analysis of the formwork support is performed based on the structural nonlinear stability theory to accurately simulate the vertical loading process of the formwork support.

[0043] Step 5: Simulation results:

[0044] After the simulation is completed and the solution is obtained, the stress, strain, node bending moment, vertical displacement, horizontal displacement and frame load data of the frame are obtained.

[0045] Preferably, in a linear buckling analysis, first find the load that makes the tangent stiffness matrix singular. , is the tangent stiffness matrix; is a non-trivial displacement solution; then the perturbation method is used to find the asymptotic solution of the dimensionless equation;

[0046] In the nonlinear buckling analysis, the initial geometric defects are first introduced based on the lowest-order instability mode of the formwork frame structure, and the discontinuous bifurcation problem at the buckling point is converted into a continuous response problem for solution; then, along the static equilibrium path in the load-displacement space, the formwork support load size is taken as an additional unknown quantity, and the arc length method is used to simultaneously solve the frame load and displacement.

[0047] Compared with the prior art, the present invention adopting the above technical solution has the following outstanding features:

[0048] The present invention constructs a safety evaluation and economic evaluation index system for the early dismantling construction of the formwork support system, accurately simulates the early dismantling construction process of the formwork support system at the construction site based on a numerical analysis method, and then evaluates and optimizes the early dismantling construction plan to obtain the best early dismantling plan that can take into account both the safety and economy of the early dismantling construction. The early dismantling construction simulation optimization method disclosed in the present invention has significant advantages such as low cost, short cycle, and repeatability, and is of great significance to the promotion and application of the early dismantling construction technology of the formwork support system. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a principle block diagram of the early dismantling construction simulation optimization construction method of the formwork support system in an embodiment of the present invention;

[0050] Figure 2 It is the original spatial structure BIM model of the non-early dismantling formwork support system at a construction site of a commercial project in an embodiment of the present invention;

[0051] Figure 3 yes Figure 2 The stress diagram of the formwork frame obtained by numerical simulation of the BIM model;

[0052] Figure 4 yes Figure 2 The vertical displacement diagram of the formwork frame obtained by numerical simulation of the BIM model;

[0053] Figure 5 yes Figure 2 The horizontal displacement diagram of the formwork frame obtained by numerical simulation of the BIM model;

[0054] Figure 6 This is a model diagram of the first preliminary early dismantling solution of the formwork support system;

[0055] Figure 7 yes Figure 6 The stress diagram of the formwork frame obtained by numerical simulation of the model;

[0056] Figure 8 yes Figure 6 Vertical displacement diagram of the formwork frame obtained by numerical simulation of the model;

[0057] Fig. 9 yes Figure 6 Horizontal displacement diagram of the formwork frame obtained by numerical simulation of the model;

[0058] Fig.10 This is a model diagram of the second preliminary early dismantling solution of the formwork support system;

[0059] Fig.11 yes Fig.10 The stress diagram of the formwork frame obtained by numerical simulation of the model;

[0060] Fig.12 yes Fig.10 Vertical displacement diagram of the formwork frame obtained by numerical simulation of the model;

[0061] Fig.13 yes Fig.10 Horizontal displacement diagram of the formwork frame obtained by numerical simulation of the model;

[0062] Fig.14 This is a model diagram of the third preliminary early dismantling solution of the formwork support system;

[0063] Fig.15 yes Fig.14 The stress diagram of the formwork frame obtained by numerical simulation of the model;

[0064] Fig.16 yes Fig.14 Vertical displacement diagram of the formwork frame obtained by numerical simulation of the model;

[0065] Fig.17 yes Fig.14 Horizontal displacement diagram of the formwork frame obtained by numerical simulation of the model. DETAILED DESCRIPTION

[0066] The present invention is further described below in conjunction with specific embodiments, the purpose of which is only to provide a better understanding of the content of the present invention. Therefore, the examples given do not limit the protection scope of the present invention.

[0067] Reference Figure 1 As shown, this embodiment provides a method for simulating and optimizing the early dismantling construction of a formwork support system, including:

[0068] S1. Conduct numerical simulation on the construction process of the non-early dismantling formwork support system, and determine the dismantling position and order of the support rods in the non-early dismantling formwork support system based on the numerical simulation results to obtain a preliminary early dismantling plan;

[0069] S2. Construct a safety evaluation index system for the formwork frame including the stress, strain, node bending moment, vertical displacement, horizontal displacement and frame load parameters, as well as an economic evaluation index system including early dismantling construction to save material costs, labor costs and indirect costs;

[0070] S3. According to the preliminary early dismantling scheme, numerical simulation of the early dismantling construction process is carried out for the non-early dismantling formwork support system, and the preliminary early dismantling scheme is evaluated based on the safety evaluation index system and the economic evaluation index system using the numerical simulation results;

[0071] S4. If the evaluation result does not meet the predetermined requirements, adjust the dismantling position and order of the support rods, propose a new preliminary early dismantling plan and return to execute S3; if the evaluation result meets the predetermined requirements, use the current preliminary early dismantling plan as the final early dismantling plan that is safe, reasonable and economical, and carry out the template early dismantling construction.

[0072] During implementation, the specific process of obtaining the preliminary early demolition plan in S1 includes:

[0073] According to the original construction design of the non-early-removal formwork support system, the early-age strength of concrete is evaluated, and then a numerical simulation model of the non-early-removal formwork support system is established that is consistent with the geometric dimensions, constraints and construction loads of the actual engineering formwork support system;

[0074] Numerical simulation is carried out based on the numerical simulation model, and the stress and deformation information of the formwork frame is extracted from the simulation results. The removal position and order of the support rods with stress and deformation less than the set conditions are determined to obtain a preliminary early removal plan.

[0075] In practice, the process of evaluating the early age strength of concrete includes:

[0076] Evaluation of early age compressive strength of concrete:

[0077] ;

[0078] in, for Compressive strength of concrete at day age; is the compressive strength of concrete at 28 days of age;

[0079] Evaluation of the elastic modulus of concrete at early age:

[0080] .

[0081] In actual construction, the poured concrete continues to harden as time goes by. Therefore, when simulating the preliminary early dismantling plan, it is necessary to consider the bearing capacity that the concrete can provide after hardening, so as to determine whether early dismantling is possible and the location of dismantling. For example, after modeling according to the original construction design plan of the non-early dismantling formwork support system, if you want to predict whether early dismantling is possible on the third day, you can calculate it according to the early age compressive strength and elastic modulus of the concrete, and use the calculation results of the compressive strength and elastic model of the concrete on the third day as constraints in the numerical simulation process, so that the simulation process is closer to the actual construction situation, and the initial early dismantling plan is determined through the stress and deformation information of the formwork frame obtained by numerical simulation.

[0082] During implementation, the template frame safety evaluation index system is expressed as follows:

[0083] ;

[0084] Where S represents the critical load factor, σ c represents the stress of the frame, ε c represents the strain of the frame, m c represents the node bending moment of the frame, v c represents the vertical displacement of the frame, h c represents the horizontal displacement of the frame, p c represents the load parameter of the frame, σ f represents the allowable stress of the frame, ε f represents the allowable strain of the frame, m f represents the allowable node bending moment of the frame, v f It represents the allowable vertical displacement of the frame, h f represents the allowable horizontal displacement of the frame, p f represents the allowable load parameter of the frame, k σ , k ε , k m , k v , k h and k p They are stress, strain, node bending moment, vertical displacement, horizontal displacement and safety multiplier of load parameter.

[0085] The stress σ of the above frame c , strain ε c , node bending moment m c , vertical displacement v c , horizontal displacement h c , load parameter p c Obtained through numerical simulation.

[0086] The above-mentioned allowable values ​​are the maximum values ​​allowed by various design parameters. They can be determined by looking up relevant technical manuals or by numerical simulation. When determined by numerical simulation, the load on the formwork frame model is continuously increased until the formwork frame is destroyed, and the values ​​of the corresponding parameters are the allowable values.

[0087] The specific value of the safety multiplier can be selected according to the actual situation of the specific project. For general concrete projects, k σ , k ε , k m , k v , k h and k p It can be taken as 0.1, 0.1, 0.1, 0.2, 0.2 and 0.3 respectively, and S can be calculated in combination with the numerical simulation results. If S < 1, it can be considered that the frame construction process meets the safety requirements.

[0088] In implementation, the economic evaluation index system is expressed as follows:

[0089] ;

[0090] Among them, C total In order to save the total construction cost, C m-s In order to save material costs, C l-s In order to save labor costs, C i-s To save indirect costs.

[0091] First, it is to save material costs. Material cost savings mainly refer to the cost savings of formwork and support materials. In the non-early demolition scheme, the formwork and support system are usually removed after the concrete reaches the designed strength, and the formwork, support and other materials have a long service life. Under the early demolition construction technology, part of the frame structure can be removed when the concrete strength reaches a certain proportion, thereby speeding up the material turnover speed and utilization efficiency and reducing the cost of construction materials. Assuming that a project requires the use of a square meter of formwork and b cubic meters of support rod materials, these materials need to be used under the non-early demolition scheme. days, while the early removal scheme only requires the use of day. The rental fee for formwork and support rod materials is Yuan / m2 (template) and Yuan / cubic meter (bracket rod). The material cost under the non-early removal plan is ; Material costs under the early demolition plan . Material cost savings = non-early dismantling solution material cost - early dismantling solution material cost, that is, , thus we can conclude that:

[0092] ;

[0093] Among them, a is the template area required for the project, Q a is the daily rental fee of the template per unit area, b is the volume of the support rod corresponding to the template, Q b is the rental fee per unit support rod per day, D t D is the number of days the formwork and support rods are used under the non-early removal construction plan, e The number of days the formwork and support rods are used under the initial early dismantling plan.

[0094] The second is labor cost savings, which refers to the labor costs for installation and removal. In the non-early removal scheme, the installation and removal of formwork and brackets require more man-hours. Under the early removal construction technology, by optimizing the construction plan, the number of installation and removal of formwork and brackets is relatively reduced, and the man-hours are also reduced accordingly. Assuming that the man-hours required for the installation and removal of formwork and brackets in the non-early removal scheme are H t , the time required for installation and removal of the formwork support under the early removal scheme is H e , n is the number of workers participating in the construction at the same time, Q l is the labor cost per worker per working hour. The labor cost under the non-early demolition plan is ; The labor cost under the early removal plan is The amount of labor cost savings = labor costs of the non-early removal scheme - labor costs of the early removal scheme, that is, , thus we can conclude that:

[0095] ;

[0096] Among them, H t H is the working hours required for the formwork engineering under the non-early removal construction plan, e is the working hours required for the formwork project under the preliminary early removal plan, n is the number of workers participating in the construction at the same time, Q l The labor cost for each worker per working hour.

[0097] The third is the indirect cost savings brought by shortening the construction period, which mainly includes equipment rental fees (such as construction auxiliary equipment, safety monitoring equipment, etc.), management fees, etc. Since the early demolition construction technology can shorten the construction period, the indirect costs such as equipment rental fees and management fees of the project will also be reduced accordingly. Assuming that the construction period under the non-early demolition scheme is days, the construction period under the early demolition plan is Equipment rental fee per day is The management fee is The indirect cost under the non-early demolition scheme is ; The indirect cost under the early demolition scheme is Indirect cost savings = indirect cost of non-early removal scheme - indirect cost of early removal scheme, that is, , thus we can conclude that:

[0098] ;

[0099] Among them, T i T is the time required for the formwork support system from construction to dismantling under the non-early dismantling construction plan. j The time required for the formwork support system from construction to dismantling under the initial early dismantling plan, Q m The daily rental fee for the equipment is n Daily management fee for the project.

[0100] During implementation, the numerical simulation process in S3 includes:

[0101] Step 1: Create a frame model:

[0102] According to the geometric dimensions of the actual formwork support system at the construction site, the actual original non-early dismantling frame model is established, and the formwork support early dismantling model is obtained according to the preliminary early dismantling plan;

[0103] Step 2: Set the node connection method:

[0104] The semi-rigid node connection method is used between the vertical rod and the horizontal rod in the support rod, and the hinge node connection method is used between the vertical rod and the diagonal rod. The friction at the hinge is negligible, so the diagonal rod is only subjected to axial force, thereby accurately simulating the mechanical behavior of the nodes in the formwork support system;

[0105] Step 3: Set boundary conditions:

[0106] The displacement freedom of the bottom of the pole is set, and a vertical downward construction load is applied to the top of the pole, so as to be consistent with the actual construction process;

[0107] Step 4: Loading process simulation:

[0108] The formwork support early dismantling model is numerically discretized, and a linear buckling analysis is performed based on the mechanical properties of the support rod material to obtain the various instability modes of the support rod. Then, the initial defect is introduced according to the lowest instability mode, and the nonlinear post-buckling analysis of the formwork support is performed based on the structural nonlinear stability theory to accurately simulate the vertical loading process of the formwork support.

[0109] Step 5: Simulation results:

[0110] After the simulation is completed and the solution is obtained, the stress, strain, node bending moment, vertical displacement, horizontal displacement and frame load data of the frame are obtained.

[0111] After the simulation of the early dismantling model of the formwork support is completed, the obtained stress, strain, node bending moment, vertical displacement, horizontal displacement and frame load parameters can be substituted into the calculation formula of the critical load coefficient S. When the calculated S is less than 1, it is determined that the preliminary early dismantling scheme meets the safety evaluation index system; after meeting the safety evaluation index system, the construction period of the formwork support system can be determined according to the specific implementation plan of the preliminary early dismantling scheme, and then the use days, working hours and other data involved in the preliminary early dismantling scheme in the economic evaluation index system can be determined (rental fees and labor costs are fixed values), and the economic cost under the preliminary early dismantling scheme can be calculated. Finally, the final cost saving can be obtained by calculating the economic cost under the non-early dismantling scheme. The cost saving is used to judge whether the economic evaluation index system is met. If the economic evaluation index system is met at the same time, the preliminary early dismantling scheme can be determined as the final early dismantling scheme.

[0112] The technical solution of the present invention is to model the non-early dismantling formwork support system through the original construction design plan of the non-early dismantling formwork support system, and analyze the stress and deformation conditions through numerical simulation, so as to determine the preliminary early dismantling plan; after the preliminary early dismantling plan is determined and when the formwork support system is actually supported and concrete is poured, the actual original non-early dismantling frame model is established according to the actual construction conditions, and the formwork support early dismantling model is obtained according to the preliminary early dismantling plan, and the stress and deformation conditions are analyzed by numerical simulation of the formwork support early dismantling model to determine whether the safety evaluation index system is met. If it is not met, the preliminary early dismantling plan is adjusted according to the stress and deformation conditions. If the safety evaluation index system is met, the construction period can be determined according to the preliminary early dismantling plan, so as to perform cost saving accounting. If the economic evaluation index system is met, the current preliminary early dismantling plan can be used as the final early dismantling plan. If the economic evaluation index system is not met, it is necessary to continue to optimize the preliminary early dismantling plan until both the safety evaluation index system and the economic evaluation index system are met.

[0113] During implementation, the frame geometry, material properties, connection methods, constraints and construction loads in the numerical simulation analysis are all based on actual engineering settings, which can ensure the accuracy of the solution. In the solution process, the frame members are simulated using beam units, and the frame nodes are simulated using connection units, which can improve the solution efficiency. During the optimization process of the early dismantling construction plan of the formwork support, each optimization is based on the simulation results of the previous step, which can quickly obtain the best early dismantling plan.

[0114] In practice, in linear buckling analysis, we first look for the load that makes the tangent stiffness matrix singular. , is the tangent stiffness matrix; is a nontrivial displacement solution; the perturbation method is then used to find the asymptotic solution to the dimensionless equation: , is the ground state stiffness, is the incremental loading stiffness, For the The first order buckling eigenvalue, For the The specific instability mode can refer to the solution process of the existing perturbation method;

[0115] In the nonlinear buckling analysis, the initial geometric defects are first introduced based on the lowest-order instability mode of the formwork frame structure, and the discontinuous bifurcation problem at the buckling point is converted into a continuous response problem for solution; then, along the static equilibrium path in the load-displacement space, the formwork support load size is taken as an additional unknown quantity, and the frame load and displacement are solved simultaneously using the arc length method: , is the current load amplitude, is the initial load, is the reference load, is the load proportional factor, , is the initial arc length increment, To specify the arc length scale factor, is the initial load proportional factor, which can be specifically referred to the solution process of the existing arc length method. The safety evaluation of formwork support construction is mainly based on the results of nonlinear post-buckling analysis, because the results of nonlinear post-buckling analysis are closer to the actual working conditions.

[0116] The early demolition construction simulation optimization method of the present invention is described below using a specific construction scenario:

[0117] Take the disc-type formwork support system of a commercial project in Tianjin as an example. The longitudinal length of the formwork area of ​​the plot is 5.7 m, the horizontal length is 5.1 m, the vertical pole step is 1.5 m, the bottom sweeping pole height is 0.4 m, the top plate under the pole extension length is 0.5 m, the formwork frame has two layers, and the total height is 10.3 m. It belongs to a tall formwork support system. The total construction period of the project is 1 month. The formwork rental fee is 1.5 yuan / square meter per day, the support pole rental fee is 12 yuan / cubic meter per day, the equipment rental fee is 2,500 yuan / day, and the management fee is 1,050 yuan / day. The construction site disc-type formwork support system is set up with BIM software for 1:1 modeling of the formwork support, such as Figure 2 As shown. Based on the simulation optimization method of the present invention, the construction plan of the formwork support system is optimized, and the expected goal is to reduce the construction cost by 35% under the premise of ensuring construction safety. The specific optimization process is as follows:

[0118] First, the geometric model of the non-early dismantling formwork support system is established according to the engineering design and construction plan. Then, the geometric model is numerically discretized to obtain the finite element model of the frame. In the modeling process, the frame vertical bars and horizontal bars are beam elements, and the diagonal bars are truss elements. Figure 2The structure shown is assembled. The connection between the vertical bar and the horizontal bar is a semi-rigid connection, and the connection between the vertical bar and the diagonal bar is a hinge connection, both of which are modeled using connection units. The material of the frame vertical bar is Q355 steel, with an elastic modulus of 206 GPa, a Poisson's ratio of 0.3, and a yield strength of 355 MPa; the material of the horizontal bar is Q235 steel, with an elastic modulus of 206 GPa, a Poisson's ratio of 0.3, and a yield strength of 235 MPa; the material of the diagonal bar is Q195 steel, with an elastic modulus of 206 GPa, a Poisson's ratio of 0.3, and a yield strength of 195 MPa; the concrete component is modeled according to the material parameters of C30 concrete when it is cured for 3 days, that is, the elastic modulus is 1.82×104 MPa and the Poisson's ratio is 0.2. According to the predetermined construction plan, the displacement freedom of the bottom node of the formwork frame is constrained, and the displacement freedom of the concrete component in the horizontal direction is constrained, and the formwork support is loaded according to the actual construction load. After solving, some numerical simulation results of frame stress, vertical displacement and horizontal displacement are as follows: Figure 3-5 As shown, specifically, Figure 3 The frame stress values ​​of different regions of the frame are shown in the figure. For example, the frame stress corresponding to the dark blue region is between 0 and 7.098. The frame stress values ​​of other regions are similar. Figure 4 The vertical displacement values ​​of different areas of the frame are shown in the figure. For example, the vertical downward displacement corresponding to the dark blue area is between 20.235 and 18.923, and the negative sign represents the vertical downward direction. The vertical displacement of other areas is similar. Figure 5 The horizontal displacement values ​​of different areas of the frame are shown in the figure. For example, the dark blue area corresponds to a horizontal left displacement between 8.092 and 6.985. The negative sign represents horizontal leftward displacement, and the positive sign represents horizontal rightward displacement. The same is true for horizontal displacement in other areas.

[0119] Based on the safety evaluation index system of the present invention, the safety of the construction scheme is evaluated. The actual values ​​and allowable values ​​of stress, strain, node bending moment, vertical displacement, horizontal displacement and loading load are obtained by numerical simulation, and the corresponding safety multiplier k σ , k ε , k m , k v , k h and k p It can be taken as 0.1, 0.1, 0.1, 0.2, 0.2 and 0.3 in sequence. During the calculation process, the stress unit is MPa, the strain has no unit, the node bending moment unit is KN·m, the vertical displacement unit is mm, the horizontal displacement unit is mm, and the loading load unit is kN. Then

[0120]

[0121] It can meet the construction safety indicators and has a large safety margin, so early demolition construction can be carried out.

[0122] According to the technical solution process of the present invention, the cost of the traditional construction solution is calculated as follows: the material costs of the formwork support under the non-early dismantling solution are the rental fees of the two-layer formwork with a longitudinal length of 5.7 m and a horizontal length of 5.1 m and the rental fees of the support with a height of 10.3 m. The formwork area is 5.7×5.1×2=58.14m 2 , the support is 5.7×5.1×10.3=299.421m³. Considering the loss, it is considered as the rental fee of 60 square meters of template and 300 cubic meters of support. The template cost is 60×1.5×30=2700 yuan, the support cost is 300×12×30=108000 yuan, and the total material cost is 2700+108000=110700 yuan. The labor cost is the cost of installing and removing 60 square meters of template and 300 cubic meters of support. It is estimated that 10 workers will enter the construction site at the same time, and the labor cost of each worker is 38 yuan per hour. The working hours required under the non-early removal plan are 35 hours, that is, the labor cost is 35×10×38=13300 yuan. Indirect costs are equipment rental fees of 2500×30=75000 and management costs of 1050×30=31500, 75000+31500=106500. Therefore, the engineering cost under the non-early demolition plan is material cost + labor cost + indirect cost, that is, 110700+13300+106500=230500 yuan.

[0123] It can be seen that the non-early demolition scheme meets the safety index and has a large safety margin, but the construction cost is high. The non-early demolition construction scheme is the starting point for the optimization of the construction scheme. According to the economic evaluation index, this scheme is equivalent to saving 0% of the cost. The scheme is further optimized according to the technical process disclosed in the present invention.

[0124] From the numerical simulation results of the construction process of the non-early demolition construction scheme under the non-early demolition scheme, it can be seen that the lower-level rods of the non-early demolition formwork support system of this project bear the deadweight of the upper and lower structures and the corresponding construction loads. The stress of the vertical rods is generally larger than that of the upper-level vertical rods. The stress at the top and bottom of the beam vertical rods with larger cross-sectional dimensions on the left side of the lower layer is the largest. The maximum displacement of the formwork support system in the vertical and horizontal directions occurs in the lower layer of the frame. Based on these stress and deformation characteristics of the frame structure, some rods with smaller stress and deformation in the frame are removed, and then the early demolition scheme 1 is given. The structural form of this early demolition scheme is as follows Figure 6 shown.

[0125] Based on the safety evaluation index system of the present invention, the safety of early demolition scheme 1 is evaluated. The actual values ​​and allowable values ​​of stress, strain, node bending moment, vertical displacement, horizontal displacement and loading load are obtained by numerical simulation. The numerical simulation results of some of the frame stress, vertical displacement and horizontal displacement are as follows: Figure 7-9 As shown; specifically, Figure 7 The frame stress values ​​of different regions of the frame are shown in the figure. For example, the frame stress corresponding to the dark blue region is between 0 and 8.244. The frame stress values ​​of other regions are similar. Figure 8 The vertical displacement values ​​of different areas of the frame are shown in the figure. For example, the vertical downward displacement corresponding to the dark blue area is between 25.336-23.655, and the negative sign represents the vertical downward direction. The vertical displacement of other areas is similar. Fig. 9 The horizontal displacement values ​​of different areas of the frame are shown in the figure. For example, the dark blue area corresponds to a horizontal left displacement between 12.978 and 10.806. The negative sign represents the horizontal left direction, and the positive sign represents the horizontal right direction. The same applies to horizontal displacements in other areas.

[0126] The corresponding safety multiplier k σ , k ε , k m , k v , k h and k p It can be taken as 0.1, 0.1, 0.1, 0.2, 0.2 and 0.3 in sequence. During the calculation process, the stress unit is MPa, the strain has no unit, the node bending moment unit is KN·m, the vertical displacement unit is mm, the horizontal displacement unit is mm, and the loading load unit is kN. Then

[0127]

[0128] It can be seen that the early demolition plan 1 can meet the construction safety indicators, and the safety margin is still large at this time.

[0129] According to the technical process disclosed in the present invention, the cost accounting of the early demolition plan 1 is carried out. Combined with the actual engineering situation, when the concrete strength reaches 37.5% of its design strength, that is, the early demolition is carried out on the third day after the concrete pouring is completed. The material cost is the rental fee of the formwork of 60 square meters and the rental fee of the bracket of 135m³ dismantled on the third day and 165m³ dismantled on the 26th day, of which the formwork cost is 60×1.5×25=2340 yuan, and the bracket cost is 135×12×3+165×12×26=56340 yuan, so the material cost under this early demolition plan is 2340+56340=58680 yuan, that is, the material cost saving amount is 110700-58680=52020 yuan. The labor hours required for construction according to the early demolition plan 1 are 28 hours, that is, the labor cost is 28×10×38=10640 yuan, and the labor cost savings are 13300-10640=2660 yuan. The indirect costs under this plan are equipment rental fees 2500×26=65000 and management fees 1050×25=27300, and the indirect cost savings are 106500-(65000+27300)=14200 yuan. Therefore, the total cost savings of the early demolition plan 1 are 52020+2660+14200=68880 yuan, which is 30% lower than the non-early demolition construction plan.

[0130] It can be seen that the early demolition scheme 1 can meet the safety index, but the reduction of construction costs has not reached the expected goal. Since the early demolition scheme 1 still has a large safety margin, the early demolition scheme is further optimized according to the technical process disclosed in the present invention.

[0131] From the numerical simulation results of the construction process of the early dismantling scheme one, it can be seen that the stress of the unremoved rods under the beams on both sides of the upper layer of the formwork support increases, and the stress distribution is relatively uniform. The stress of the unremoved vertical rods under the left beam of the lower layer increases significantly, and the maximum stress occurs at the node where the vertical rods under the beams are connected to the horizontal rods. The maximum vertical displacement of the frame occurs at the left rear of the upper layer of the frame; the maximum horizontal displacement is located at the left rear of the lower layer of the frame. Based on these stress and deformation characteristics of the frame structure, the rods with smaller stress and deformation in the early dismantling scheme one are continued to be dismantled, and then the early dismantling construction scheme two of the formwork support is obtained. The structural form of the early dismantling scheme two is as follows Fig.10 shown.

[0132] Based on the safety evaluation index system disclosed in the present invention, the safety of the early demolition scheme 2 is evaluated. The actual values ​​and allowable values ​​of stress, strain, node bending moment, vertical displacement, horizontal displacement and loading load are obtained by numerical simulation. The numerical simulation results of the frame stress, vertical displacement and horizontal displacement are shown in the figure. Figure 11-13 As shown; specifically, Fig.11The frame stress values ​​of different regions of the frame are shown in the figure. For example, the frame stress corresponding to the dark blue region is between 0 and 14.782. The frame stress values ​​of other regions are similar. Fig.12 The vertical displacement values ​​of different areas of the frame are shown in the figure. For example, the vertical downward displacement corresponding to the dark blue area is between 53.138 and 49.702, and the negative sign represents the vertical downward direction. The vertical displacement of other areas is similar. Fig.13 The horizontal displacement values ​​of different areas of the frame are shown in the figure. For example, the dark blue area corresponds to a horizontal left displacement between 24.773 and 20.506. The negative sign represents the horizontal left direction, and the positive sign represents the horizontal right direction. The same applies to horizontal displacements in other areas.

[0133] The corresponding safety multiplier k σ , k ε , k m , k v , k h and k p It can be taken as 0.1, 0.1, 0.1, 0.2, 0.2 and 0.3 in sequence. During the calculation process, the stress unit is MPa, the strain has no unit, the node bending moment unit is KN·m, the vertical displacement unit is mm, the horizontal displacement unit is mm, and the loading load unit is kN. Then

[0134]

[0135] The construction safety indicators are not met.

[0136] According to the technical process disclosed in the present invention, since the early demolition plan 2 does not meet the safety index, it is not necessary to calculate the cost of the early demolition plan 2, but in order to fully illustrate the characteristics of the plan, the construction cost of the early demolition plan 2 is also calculated here. Combined with the actual project situation, the material cost is the rental fee of the template of 60 square meters and the rental fee of the bracket of 163m³ dismantled on the 3rd day and 137m³ dismantled on the 20th day, of which the template cost is 60×1.5×20=1800 yuan, and the bracket cost is 163×12×3+137×12×20=38748 yuan, so the material cost under this early demolition plan is 1800+38748=40548 yuan, that is, the material cost saving amount is 110700-40548=70152 yuan. The labor hours required for construction according to the early demolition plan 2 are 28 hours, that is, the labor cost is 28×10×38=10640 yuan, and the labor cost savings are 13300-10640=2660 yuan. The indirect costs under this plan are equipment rental fees of 2500×20=50000 and management fees of 1050×25=21000, and the indirect cost savings are 106500-(50000+21000)=35500 yuan. Therefore, the total cost savings of the early demolition plan 2 are 70152+2660+35500=108312 yuan, which is 47% lower than the non-early demolition construction plan.

[0137] It can be seen that the early dismantling scheme 2 cannot meet the construction safety index and therefore cannot be used as a reasonable construction scheme. From the construction cost accounting, it can be seen that due to the early dismantling of a large number of frame members, the cost savings of the early dismantling scheme 2 far exceeded the expected economic index, but the early dismantling of a large number of members also led to insufficient bearing capacity of the frame. The early dismantling scheme is further optimized below.

[0138] From the numerical simulation results of the construction process of the early dismantling scheme 2, it can be seen that the upper and lower layers of the formwork support system in the early dismantling scheme 2 are both under stress, and due to the removal of the lower vertical bars on both sides of the upper middle beam, the lower vertical bars in the middle of the beam span have local uneven stress and deformation. At this time, the maximum vertical displacement of the frame occurs in the right front of the upper layer of the frame, and the maximum horizontal displacement occurs in the right rear of the lower layer of the frame. Based on these stress and deformation characteristics of the frame structure, by appropriately reducing the number of frame rods removed and increasing the support at the position where the formwork support is locally stressed and deformed, the early dismantling construction scheme 3 of the formwork support is obtained. The structural form of the early dismantling scheme 3 is as follows: Fig.14 shown.

[0139] Based on the safety evaluation index system disclosed in the present invention, the safety of early demolition scheme 3 is evaluated. The actual values ​​and allowable values ​​of stress, strain, node bending moment, vertical displacement, horizontal displacement and loading load are obtained by numerical simulation. The numerical simulation results of some of the frame stress, vertical displacement and horizontal displacement are as follows: Figure 15-17 As shown; specifically, Fig.15 The frame stress values ​​of different regions of the frame are shown in the figure. For example, the frame stress corresponding to the dark blue region is between 0 and 10.236. The frame stress values ​​of other regions are similar. Fig.16 The vertical displacement values ​​of different areas of the frame are shown in the figure. For example, the vertical downward displacement corresponding to the dark blue area is between 38.626 and 36.133, and the negative sign represents the vertical downward direction. The vertical displacement of other areas is similar. Fig.17 The horizontal displacement values ​​of different areas of the frame are shown in the figure. For example, the dark blue area corresponds to a horizontal left displacement between 16.153 and 13.465. The negative sign represents the horizontal left direction, and the positive sign represents the horizontal right direction. The same applies to horizontal displacements in other areas.

[0140] The corresponding safety multiplier k σ , k ε , k m , k v , k h and k p It can be taken as 0.1, 0.1, 0.1, 0.2, 0.2 and 0.3 in sequence. During the calculation process, the stress unit is MPa, the strain has no unit, the node bending moment unit is KN·m, the vertical displacement unit is mm, the horizontal displacement unit is mm, and the loading load unit is kN. Then

[0141]

[0142] Able to meet construction safety indicators.

[0143] Cost accounting for early demolition plan 3: combined with the actual project situation, the material cost is the rental fee of 60 square meters of templates and the rental fee of 152m³ removed on the 3rd day and 148m³ removed on the 23rd day. The template cost is 60×1.5×23=2070 yuan, and the bracket cost is 152×12×3+148×12×23=46320 yuan. Therefore, the material cost under this early demolition plan is 2070+46320=48390 yuan, that is, the material cost savings are 110700-48390=62310 yuan. The construction time required for early demolition plan 3 is 28 hours, that is, the labor cost is 28×10×38=10640 yuan, and the labor cost savings are 13300-10640=2660 yuan. The indirect costs under this plan are equipment rental fees of 2500×23=57500 and management fees of 1050×23=24150, and the indirect cost savings are 106500-(57500+24150)=24850 yuan. Therefore, the total cost savings of early demolition plan 3 is 62310+2660+24850=89820 yuan, which is 39% lower than the non-early demolition construction plan.

[0144] It can be seen that the early dismantling scheme 3 not only meets the safety index of the formwork support construction, but also meets the expected cost saving economic index. In addition, the numerical simulation results of the construction process of the early dismantling scheme 3 show that the frame rods in the early dismantling scheme 3 are subjected to relatively uniform force, and no obvious instability occurs. It is a safe, reasonable and economical early dismantling construction scheme, and the optimization process ends here.

[0145] The above description is only the preferred embodiment of the present invention, and does not limit the scope of rights of the present invention. All equivalent changes made by using the contents of the present invention specification and its drawings are included in the scope of rights of the present invention.

Claims

1. A method for simulating and optimizing the early dismantling of a formwork support system, characterized in that: include: S1. Conduct numerical simulation on the construction process of the non-early dismantling formwork support system, and determine the dismantling position and order of the support rods in the non-early dismantling formwork support system based on the numerical simulation results to obtain a preliminary early dismantling plan; S2. Construct a safety evaluation index system for the formwork frame including the stress, strain, node bending moment, vertical displacement, horizontal displacement and frame load parameters, as well as an economic evaluation index system including early dismantling construction to save material costs, labor costs and indirect costs; S3. According to the preliminary early dismantling scheme, numerical simulation of the early dismantling construction process is carried out for the non-early dismantling formwork support system, and the preliminary early dismantling scheme is evaluated based on the safety evaluation index system and the economic evaluation index system using the numerical simulation results; S4. If the evaluation result does not meet the predetermined requirements, adjust the dismantling position and order of the support rods, propose a new preliminary early dismantling plan and return to execute S3; if the evaluation result meets the predetermined requirements, use the current preliminary early dismantling plan as the final early dismantling plan that is safe, reasonable and economical, and carry out the early dismantling construction.

2. The method for simulating and optimizing the early dismantling construction of the formwork support system according to claim 1 is characterized in that: The specific process of obtaining the preliminary early demolition plan in S1 includes: According to the original construction design of the non-early-removal formwork support system, the early-age strength of concrete is evaluated, and a numerical simulation model of the non-early-removal formwork support system is established that is consistent with the geometric dimensions, constraints and construction loads of the actual engineering formwork support system; Numerical simulation is carried out based on the numerical simulation model, and the stress and deformation information of the formwork frame is extracted from the simulation results. The removal position and order of the support rods with stress and deformation less than the set conditions are determined to obtain a preliminary early removal plan.

3. The method for simulating and optimizing the early dismantling construction of the formwork support system according to claim 2 is characterized in that: The process of assessing the early age strength of concrete includes: Evaluation of early age compressive strength of concrete: ； in, for Compressive strength of concrete at day age; is the compressive strength of concrete at 28 days of age; Evaluation of the elastic modulus of concrete at early age: 。 4. The method for simulating and optimizing the early dismantling construction of the formwork support system according to claim 1 is characterized in that: The safety evaluation index system of the formwork frame is expressed as follows: ； Where S represents the critical load factor, σ c represents the stress of the frame, ε c represents the strain of the frame, m c represents the node bending moment of the frame, v c represents the vertical displacement of the frame, h c represents the horizontal displacement of the frame, p c represents the load parameter of the frame, σ f represents the allowable stress of the frame, ε f represents the allowable strain of the frame, m f represents the allowable node bending moment of the frame, v f It represents the allowable vertical displacement of the frame, h f represents the allowable horizontal displacement of the frame, p f represents the allowable load parameter of the frame, k σ , k ε , k m , k v , k h and k p They are stress, strain, node bending moment, vertical displacement, horizontal displacement and safety multiplier of load parameter.

5. The method for simulating and optimizing the early dismantling construction of the formwork support system according to claim 1 is characterized in that: The economic evaluation index system is expressed as follows: ； Among them, C total In order to save the total construction cost, C m-s In order to save material costs, C l-s In order to save labor costs, C i-s To save indirect costs; ； Among them, a is the template area required for the project, Q a is the daily rental fee of the template per unit area, b is the volume of the support rod corresponding to the template, Q b is the rental fee per unit support rod per day, D t D is the number of days the formwork and support rods are used under the non-early removal construction plan, e The number of days the formwork and support rods are used under the preliminary early removal plan; ； Among them, H t H is the working hours required for the formwork engineering under the non-early removal construction plan, e is the working hours required for the formwork project under the preliminary early removal plan, n is the number of workers participating in the construction at the same time, Q l The labor cost for each worker per working hour; ； Among them, T i T is the time required for the formwork support system from construction to dismantling under the non-early dismantling construction plan. j The time required for the formwork support system from construction to dismantling under the initial early dismantling plan, Q m The daily rental fee for the equipment is n Daily management fee for the project.

6. The method for simulating and optimizing the early dismantling construction of the formwork support system according to claim 1 is characterized in that: The numerical simulation process in S3 includes: Step 1: Create a frame model: According to the geometric dimensions of the actual formwork support system at the construction site, the actual original non-early dismantling frame model is established, and the formwork support early dismantling model is obtained according to the preliminary early dismantling plan; Step 2: Set the node connection method: The semi-rigid node connection method is used between the vertical rod and the horizontal rod in the support rod, and the hinge node connection method is used between the vertical rod and the diagonal rod. The friction at the hinge is negligible, so the diagonal rod is only subjected to axial force, thereby accurately simulating the mechanical behavior of the nodes in the formwork support system; Step 3: Set boundary conditions: The displacement freedom of the bottom of the pole is set, and a vertical downward construction load is applied to the top of the pole, so as to be consistent with the actual construction process; Step 4: Loading process simulation: The formwork support early dismantling model is numerically discretized, and a linear buckling analysis is performed based on the mechanical properties of the support rod material to obtain the various instability modes of the support rod. Then, the initial defect is introduced according to the lowest instability mode, and the nonlinear post-buckling analysis of the formwork support is performed based on the structural nonlinear stability theory to accurately simulate the vertical loading process of the formwork support. Step 5: Simulation results: After the simulation is completed and the solution is obtained, the stress, strain, node bending moment, vertical displacement, horizontal displacement and frame load data of the frame are obtained.

7. The method for simulating and optimizing the early dismantling construction of the formwork support system according to claim 6 is characterized in that: In linear buckling analysis, we first look for the load that makes the tangent stiffness matrix singular. , is the tangent stiffness matrix; is a non-trivial displacement solution; then the perturbation method is used to find the asymptotic solution of the dimensionless equation; In the nonlinear buckling analysis, the initial geometric defects are first introduced based on the lowest-order instability mode of the formwork frame structure, and the discontinuous bifurcation problem at the buckling point is converted into a continuous response problem for solution; then, along the static equilibrium path in the load-displacement space, the formwork support load size is taken as an additional unknown quantity, and the arc length method is used to simultaneously solve the frame load and displacement.

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