Construction method of prefabricated hollow square column

Abstract

The invention provides a construction method of a prefabricated hollow square column, and belongs to the technical field of building construction, and the construction method of the prefabricated hollow square column realizes scientific layout of a control network by establishing a measurement control network optimization equation set. The method comprises the following steps: firstly, performing construction preparatory work and determining quality standards; then adopting a minimum spanning tree algorithm to optimize control point layout, and establishing a measurement control network; checking a cast-in-place column reserved connecting joint bar and mounting a positioning plate, and mounting the prefabricated hollow square column in place by using a hoisting tool; connecting the reinforcing steel bars by adopting cold-pressed sleeves and pouring concrete; a theodolite is used for correcting perpendicularity and levelness, and a temporary support is installed for fixing; and finally, node reinforcement, waterproof treatment and quality acceptance are conducted. According to the method, through theoretical guidance practice, the technical problem of insufficient measurement control precision in the construction process of the prefabricated hollow square column is systematically solved; the technical problem of installation error accumulation caused by insufficient measurement control precision in the construction process of the prefabricated hollow square column can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and in particular relates to a construction method of a prefabricated hollow square column. Background Art

[0002] Prefabricated hollow square columns, a new type of building component, are increasingly being used in modern architecture due to their advantages such as light weight, high strength, and convenient construction. Traditional prefabricated hollow square column construction primarily relies on conventional surveying methods to establish a control network, including the use of total stations and levels for axis and elevation control, with manual assistance for installation positioning and calibration. This traditional surveying and control method performs well for small projects or those with a small number of components. However, it suffers from insufficient positioning accuracy in large, complex structures or projects requiring high precision.

[0003] However, conventional measurement and control methods have numerous drawbacks. These include a lack of scientific basis for the placement of measurement control points, which often rely on empirical evidence; inadequate optimization of the control network structure, which leads to amplified errors; arbitrary observation plans and sequences, lacking systematic considerations; and a significant accumulation of measurement errors, which gradually amplifies errors in subsequent construction stages. These issues are particularly prominent during the continuous installation of multi-story prefabricated components, directly impacting component installation accuracy and the overall quality of the structure.

[0004] Traditional methods struggle to effectively address the cumulative error effects of surveying and control network deployment during the construction of prefabricated hollow square columns in large-scale projects. This is particularly true when the number of control points increases and the measurement environment becomes complex. Scientifically deploying the control network and optimizing the observation scheme to improve positioning accuracy are pressing technical challenges. Existing technologies lack systematic, mathematically model-supported surveying and control network optimization methods, making it difficult to achieve high-precision installation requirements. This means that insufficient surveying and control accuracy during the construction of prefabricated hollow square columns can lead to cumulative installation errors. Summary of the Invention

[0005] In view of this, the present invention provides a construction method for prefabricated hollow square columns, which can solve the technical problem in the prior art that insufficient measurement and control accuracy during the construction of prefabricated hollow square columns leads to accumulated installation errors.

[0006] The present invention is achieved in that:

[0007] The invention provides a construction method for prefabricated hollow square columns, which comprises: carrying out construction preparation work; establishing a minimum spanning tree measurement control network according to the plane layout of a building, setting control piles and leveling points, the measurement control network adopts a minimum spanning tree algorithm to optimize the layout positions of control points, calculates the optimal connection path through the control point position coordinate matrix and the distance weight matrix, reduces the accumulation of measurement errors, uses a total station to set the edge lines and control lines of the prefabricated hollow square columns on a foundation cushion layer, uses a level to measure and mark the installation elevation; installs positioning plates to prevent the connection steel bars from deviating; installs the prefabricated hollow square columns; connects the prefabricated hollow square columns with cast-in-place columns; corrects the position of the prefabricated hollow square columns; installs temporary supports; checks connection nodes; and accepts the prefabricated hollow square columns; the layout of the minimum spanning tree measurement control network is calculated by a measurement control network optimization equation group.

[0008] On the basis of the above technical solution, the construction method of a prefabricated hollow square column of the present invention can also be improved as follows: wherein, the measurement control network optimization equation group includes point layout equations, error propagation equations, network strength equations, and observation scheme equations.

[0009] Furthermore, the point layout equation is used to determine the optimal position of the measurement control point. The input includes the building plane coordinate matrix, the prefabricated hollow square column layout position matrix, the site constraint matrix, the instrument sight range, and the instrument accuracy parameters. The output is a set of measurement control point coordinates.

[0010] Furthermore, the error propagation equation is used to calculate the error transmission law and cumulative effect in the measurement control network. The input includes the measurement control point coordinate set, the number of observation edges, the instrument angle measurement accuracy, the instrument distance measurement accuracy, and the atmospheric influence factor. The output is the error ellipse parameter set.

[0011] Furthermore, the grid strength equation is used to evaluate the impact of the geometric shape of the measurement control network on accuracy. The input includes the measurement control point coordinate set, the observation scheme matrix, the error ellipse parameter set, the azimuth distribution, and the side length distribution. The output is the grid strength index.

[0012] Furthermore, the observation scheme equation is used to generate the optimal measurement sequence and path. The input includes the measurement control point coordinate set, the number of instrument stations, the observation edge weight, the obstacle distribution, and the line-of-sight condition. The output is the measurement observation sequence and path diagram.

[0013] Furthermore, the step of installing the positioning plate to prevent the connection steel bars from being displaced includes: inspecting the reserved connection dowels of the cast-in-place columns, installing the positioning plate to prevent the connection steel bars from being displaced, inspecting the appearance of the prefabricated hollow square columns to ensure there are no quality defects, and checking that the model specifications are consistent with the design drawings.

[0014] Furthermore, the steps of installing the prefabricated hollow square column include: using a lifting tool to install the prefabricated hollow square column at a designated position, ensuring that the lifting tool is firmly installed and evenly stressed, and slowly lifting the prefabricated hollow square column to the installation position so that it is aligned with the reserved connecting dowels and positioning plates; the prefabricated hollow square column is a hollow square structure made of high-strength concrete, with a steel cage inside, embedded parts distributed around it for connection with the upper and lower structures, and reserved holes on the side for passing water and electricity pipelines.

[0015] Furthermore, the step of connecting the prefabricated hollow square column and the cast-in-place column includes: the lower connecting steel bars of the prefabricated hollow square column are butt-connected with the reserved connecting dowel bars of the cast-in-place column by using a cold-pressed sleeve method to ensure that the connection part is firm and reliable, and then concrete is poured layer by layer in the cavity of the hollow square column and vibrated to make it dense.

[0016] Furthermore, the positioning plate is a fixing device installed on the reserved connecting dowel bar, which is used to prevent the reserved connecting steel bars from being displaced during the subsequent construction process, improve the positioning accuracy of the steel bars, and reduce construction errors; the cold-pressed sleeve is a mechanical connection device for steel bars, which tightly connects the sleeve and the steel bars through a cold extrusion process to achieve reliable connection of the ends of the steel bars; the connecting clip is a device embedded in the prefabricated hollow square column and connected to the temporary support rod.

[0017] This paper proposes a method for constructing prefabricated hollow square columns based on a minimum spanning tree algorithm to optimize the measurement control network. By establishing a set of measurement control network optimization equations, including point placement equations, error propagation equations, network shape and strength equations, and observation scheme equations, this method achieves scientific layout and optimization of the measurement control network. This method overcomes the limitations of traditional empirical network layout methods by applying the minimum spanning tree algorithm from graph theory to the field of engineering surveying, resulting in a more rational control network structure.

[0018] This method solves the problem of error accumulation caused by improper measurement control network layout in traditional construction methods. It uses point layout equations to determine optimal control point locations, error propagation equations to analyze error transmission patterns, mesh strength equations to assess mesh geometric strength, and observation scheme equations to generate optimal measurement paths, forming a complete measurement control system. This mathematical model-based measurement control network optimization method significantly reduces measurement error accumulation and improves prefabricated component installation accuracy.

[0019] The present invention successfully solves the technical problem of insufficient measurement control accuracy during the construction of prefabricated hollow square columns. This is mainly due to the combination of the graph theory minimum spanning tree algorithm and the principles of surveying to establish a scientific measurement control network optimization equation group. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a flowchart of a construction method of a prefabricated hollow square column;

[0021] Figure 2 This is a schematic diagram of a prefabricated hollow square column;

[0022] Figure 3 This is a schematic diagram of the internal structure of a prefabricated hollow square column;

[0023] Figure 4 This is a schematic diagram of the layout of a prefabricated hollow square column;

[0024] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0025] 10. Prefabricated hollow square column; 11. Reserved holes; 12. Connecting clips; 13. Cast-in-place column; 20. Positioning plate; 30. Cold-pressed sleeve; 31. Sleeve; 32. Reserved connecting dowels; 33. Cold-pressed sleeve indentation; 34. Connecting steel bars; 40. Temporary support rod. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0027] like Figure 1 FIG. 1 is a flow chart of a construction method of a prefabricated hollow square column provided by the present invention, and the method comprises the following steps:

[0028] S01. Conduct construction preparation work, organize technical personnel to study construction drawings, prepare detailed construction plans, clarify construction process and quality standards, prepare prefabricated hollow square columns, steel bars, concrete, embedded parts and other materials, and equip lifting equipment and measuring instruments;

[0029] S02. Establish a minimum spanning tree measurement control network based on the building plan layout, set control stakes and leveling points, use a minimum spanning tree algorithm to optimize the control point layout positions, calculate the optimal connection path using the control point position coordinate matrix and the distance weight matrix to reduce measurement error accumulation, use a total station to set the prefabricated hollow square column edge lines and control lines on the foundation cushion, and use a level to measure and mark the installation elevation; the minimum spanning tree measurement control network layout is calculated using the measurement control network optimization equation group;

[0030] S03. Check the reserved connecting bars of cast-in-place columns, install positioning plates to prevent the connecting bars from shifting, check the appearance of prefabricated hollow square columns to ensure there are no quality defects, and verify that the model and specifications are consistent with the design drawings;

[0031] S04. Use the lifting tool to install the prefabricated hollow square column in the designated position, ensuring that the lifting tool is firmly installed and evenly stressed. Slowly lift the prefabricated hollow square column to the installation position, aligning it with the reserved connecting dowel and positioning plate;

[0032] S05. The lower connecting steel bars of the prefabricated hollow square columns are butt-jointed to the reserved connecting bars of the cast-in-place columns using a cold-pressed sleeve method to ensure a firm and reliable connection. Subsequently, concrete is poured layer by layer into the hollow square column cavity and vibrated to compact it.

[0033] S06. Use a theodolite to calibrate the verticality of the prefabricated hollow square columns and a spirit level to calibrate the horizontality to ensure that the deviation is within the allowable range of the specification. Use temporary supports to prevent displacement or tilting during subsequent construction.

[0034] S07. Pre-embed connecting clips on the prefabricated hollow square column. Install a temporary support rod, connect one end to the connecting clip and the other end to the ground or the completed structure. Regularly check the temporary support system to ensure stability.

[0035] S08. Inspect the connection points between prefabricated hollow square columns and cast-in-place columns to ensure that the structure meets the design requirements. Use steel bars or steel plates to reinforce them to increase the bearing capacity. Waterproof the connection points to prevent rainwater infiltration.

[0036] S09. After the final setting of the concrete, the prefabricated hollow square columns shall be inspected and accepted, including appearance inspection to confirm that there are no quality defects such as cracks, honeycombs and rough surfaces; dimensional inspection to ensure that the deviation of the cross-sectional dimensions, height, verticality and horizontality are within the allowable range; and connection inspection to confirm that the connection parts are firm.

[0037] The measurement control network optimization equation group includes point layout equation, error propagation equation, network strength equation and observation scheme equation;

[0038] The point layout equation is used to determine the optimal position of the measurement control points. The input includes the building plane coordinate matrix, the prefabricated hollow square column layout position matrix, the site constraint matrix, the instrument sight range, and the instrument accuracy parameter. The output is the measurement control point coordinate set.

[0039] The error propagation equation is used to calculate the error propagation law and cumulative effect in the measurement control network. The input includes the coordinate set of the measurement control point, the number of observation edges, the instrument angle measurement accuracy, the instrument distance measurement accuracy, and the atmospheric influence factor. The output is the error ellipse parameter set.

[0040] The grid strength equation is used to evaluate the influence of the geometric shape of the measurement control network on the accuracy. The input includes the coordinate set of the measurement control points, the observation scheme matrix, the error ellipse parameter set, the azimuth distribution, and the side length distribution. The output is the grid strength index.

[0041] The observation plan equation is used to generate the optimal measurement sequence and path. The input includes the measurement control point coordinate set, the number of instrument stations, the observation edge weight, the obstacle distribution, and the line of sight conditions. The output is the measurement observation sequence and path diagram.

[0042] Among them, the positioning plate is specifically a fixing device installed on the reserved connecting dowel bar, which is used to prevent the reserved connecting steel bars from being displaced during the subsequent construction process, improve the steel bar positioning accuracy, and reduce construction errors.

[0043] Among them, the cold-pressed sleeve is specifically a mechanical connection device for steel bars, which tightly connects the sleeve and the steel bars through a cold extrusion process to achieve reliable connection of the steel bar ends, and has the characteristics of high connection strength and fast construction speed.

[0044] Among them, the connecting clip is specifically a device embedded in the prefabricated hollow square column and connected to the temporary support rod. The design conforms to the principles of mechanics and has sufficient strength and rigidity to ensure the stability of the temporary support system.

[0045] Among them, the prefabricated hollow square column is specifically a hollow square structure made of high-strength concrete, with a steel cage inside, embedded parts distributed around it for connecting with the upper and lower structures, and reserved holes on the side for passing water and electricity pipelines. It has the advantages of light weight, high strength, and convenient construction.

[0046] like Figure 2-4 As shown, the specific implementation of the above steps is described in detail below.

[0047] The specific implementation of step S01 involves comprehensive preparatory work before construction. First, professional technicians conduct in-depth research and analysis of the prefabricated hollow square column construction drawings to understand the design requirements and technical parameters. A detailed construction plan is then compiled, clarifying the construction process flow and establishing quality control standards and inspection methods. Next, materials are prepared, including prefabricated hollow square column components, connecting steel bars, high-strength concrete, and embedded parts. Quality inspections are conducted to ensure that these materials meet design requirements. Finally, hoisting equipment such as tower cranes and mobile cranes are deployed, along with precision measuring instruments such as total stations, levels, and theodolites. This thorough preparation ensures smooth construction, reduces errors and rework, and improves construction efficiency and quality.

[0048] The specific implementation of step S02 involves establishing a survey control network based on a minimum spanning tree algorithm. First, the coordinates of the prefabricated hollow square columns are determined based on the building plan and a distance adjacency matrix is constructed. Next, the Prim algorithm or Kruskal algorithm is used to calculate the minimum spanning tree and optimize the placement of control points. Control stakes and leveling points are then set, with control stake spacing typically 30 to 50 meters and leveling accuracy controlled within ±1 mm. A total station is used to stake out the prefabricated hollow square columns according to the control network coordinates on the foundation cushion, marking the edges and axes of the columns with a positional deviation within ±3 mm. A level is then used to measure and mark the installation elevation, with an elevation error within ±2 mm. The survey control network optimization equations are calculated using point placement equations to determine the optimal control point locations. Error propagation equations analyze the cumulative effect of errors. A grid strength equation assesses the impact of the control network geometry on accuracy. Finally, an observation plan equation generates the optimal measurement path. The goal of this step is to establish a high-precision survey control system to ensure the accurate installation of the prefabricated hollow square columns.

[0049] The specific implementation method of step S03 is to conduct a comprehensive inspection of the prefabricated components and connection points before installation. First, check whether the position, quantity, and specifications of the reserved connection dowels for the cast-in-place columns are consistent with the design drawings, with deviations controlled within ±5mm. Then, install the positioning plate on the reserved connection dowels. The positioning plate is made of steel material with a thickness of 8-12mm and is fixed by welding or bolting. It can withstand lateral forces of more than 2000N. Next, check the appearance quality of the prefabricated hollow square columns, including surface flatness, angular integrity, and the presence of defects such as cracks, honeycombs, and rough surfaces. The surface flatness deviation is controlled within 5mm / 2m. Finally, check the model, specifications, and dimensions of the prefabricated hollow square columns for consistency with the design drawings. The cross-sectional dimension error is controlled within ±5mm, and the length error is controlled within ±10mm. The purpose of this step is to ensure that the quality of the prefabricated components and the connection conditions meet the installation requirements through strict inspection, laying the foundation for subsequent construction.

[0050] The specific implementation method of step S04 is to use a lifting tool to install the prefabricated hollow square column. First, a suitable lifting tool is selected. The tool design uses finite element analysis to ensure uniform force and a safety factor of not less than 1.5; then, a lifting point is set on the prefabricated hollow square column. The lifting point position is usually above the center of gravity of the component. A high-strength lifting ring is used with a bearing capacity of not less than 2 times the weight of the component; then the lifting tool is connected to the lifting equipment to check the connection reliability; the prefabricated hollow square column is slowly lifted, and the lifting speed is controlled within 0.5m / min to keep the component stable; finally, the prefabricated hollow square column is aligned with the installation position so that its steel bars are accurately connected to the reserved connecting bars of the cast-in-place column, and the alignment deviation is controlled within ±3mm and the height deviation is controlled within ±2mm. The purpose of this step is to safely position the prefabricated hollow square column through precise lifting technology to ensure installation accuracy and construction safety.

[0051] Step S05 involves connecting the prefabricated hollow square column to the cast-in-place structure. First, the cold-pressed sleeve connection technique is used to connect the lower connecting steel bars of the prefabricated hollow square column to the reserved connecting dowel bars of the cast-in-place column. The cold-pressed sleeve is made of carbon steel with a wall thickness of no less than 2 mm and a length of 3 to 4 times the diameter of the steel bar. The cold-pressed sleeve is pressed using hydraulic cold extrusion equipment with a pressure of 300 to 400 MPa. The connection quality is then checked to ensure that the cold-pressed sleeve indentation is uniform and free of looseness. Concrete is then poured into the prefabricated hollow square column cavity in layers. The concrete strength grade is no less than C30, and the thickness of each layer is controlled at 300 to 500 mm. High-frequency vibrating rods are used for 20 to 30 seconds to ensure that the concrete density reaches above 98%. Finally, the concrete is cured at a temperature of 15 to 25°C for no less than 7 days. This step ensures that the prefabricated hollow square column and the foundation structure are integrated through reliable connection methods and pouring techniques, improving the structural integrity and load-bearing capacity.

[0052] The specific implementation method of step S06 is to accurately calibrate the prefabricated hollow square columns after installation. First, use a high-precision theodolite to check the verticality of the columns, measuring from two mutually perpendicular directions, with no fewer than three measurement points. Then, calculate the verticality deviation based on the measurement results, and control the verticality deviation within the range of H / 1000 and no more than 15mm (H is the column height). Then, use adjustment tools such as jacks or wedges to fine-tune, and control the adjustment force within 10% of the component's bearing capacity. Use a high-precision level to calibrate the horizontality, and control the horizontality deviation within the range of L / 1000 and no more than 10mm (L is the column width). Finally, after reaching the designed position, install temporary supports to fix them. The support angle is 45 to 60 degrees, and the support cross-sectional dimensions are determined according to calculations, generally no less than 100mm x 100mm. The purpose of this step is to ensure that the installation accuracy of the prefabricated hollow square columns meets the requirements of the specifications through precise calibration technology, ensuring the geometric accuracy of the structure.

[0053] The specific implementation method of step S07 is to install a temporary support system to ensure the stability of the prefabricated hollow square column. First, a connecting clip is embedded on the column body of the prefabricated hollow square column. The connecting clip is made of Q345 steel with a thickness of 8 to 12 mm, a bearing capacity of not less than 50 kN, and an embedment depth of not less than 80 mm. Then, a temporary support rod is installed. The support rod material is Q235 steel. The length is determined according to the site conditions, generally 1.2 to 1.5 times the column height, with a diameter of not less than 48 mm and a wall thickness of not less than 3.5 mm. One end of the support rod is connected to the connecting clip using a pin connection method with a pin diameter of not less than 20 mm. The other end is connected to the ground or a completed structure. The ground connection point is fixed with an expansion bolt with a bolt diameter of not less than 16 mm and an embedment depth of not less than 100 mm. The temporary support system is regularly inspected at a frequency of 72 hours per time. The inspection content includes support looseness, deformation, and connection point stability. The purpose of this step is to ensure the stability of the prefabricated hollow square columns after installation and during subsequent construction through a reliable temporary support system to prevent displacement or tilting due to external forces.

[0054] The specific implementation of step S08 is to strengthen the connection nodes between the prefabricated hollow square columns and the cast-in-place structure. First, the connection nodes are visually inspected, including the concrete density, steel bar connection status, and embedded parts position. Then, according to the design requirements, the connection nodes are reinforced with steel bars or steel plates. The diameter of the reinforcement steel bars is not less than 12mm, the spacing is 100-150mm, the thickness of the reinforcement steel plates is not less than 8mm, and the contact area with the concrete is not less than 200cm. 2 Next, waterproof the connection points using a flexible waterproofing material, either applied or wrapped. The waterproofing layer should be at least 2mm thick, with a tensile strength of at least 1.5MPa and an elongation of at least 300%. Finally, inspect the waterproofing to ensure there are no leaks. This step aims to improve the reliability and durability of the connection between the precast hollow square columns and the cast-in-place structure by strengthening the connection points with reinforced and waterproofed measures.

[0055] The specific implementation of step S09 is to conduct a comprehensive acceptance inspection after the installation of the prefabricated hollow square column. First, after the concrete has finally set (generally 2-3 days after pouring), an appearance inspection is carried out. The inspection content includes whether there are quality defects such as cracks, honeycombs, and pitting on the surface. The crack width must not exceed 0.2mm, and the crack depth must not exceed the thickness of the protective layer. Then, a dimensional inspection is carried out to check the cross-sectional dimensions, height, verticality, and horizontality. The cross-sectional dimension deviation is controlled within ±5mm, the height deviation is controlled within ±10mm, the verticality deviation is controlled within the range of H / 1000 and no more than 15mm, and the horizontality deviation is controlled within the range of L / 1000 and no more than 10mm. Then, a connection inspection is carried out. The inspection content includes the quality of the cold-pressed sleeve connection, the connection status of the embedded parts, and the density of the concrete pouring. Non-destructive testing methods such as ultrasonic testing are used to assess the connection strength. The connection strength must not be less than 95% of the design strength. Finally, an acceptance report is compiled to record the acceptance results and the corresponding treatment measures. The purpose of this step is to ensure that the installation quality of the prefabricated hollow square column meets the design and specification requirements through a strict acceptance procedure, thereby ensuring the quality of the project.

[0056] The mathematical model or calculation process involved in the present invention is described in detail below.

[0057] The minimum spanning tree algorithm in step S02 is used to optimize the control point layout positions, and its calculation process is specifically expressed as follows:

[0058] First, construct the distance adjacency matrix D according to the building layout:

[0059]

[0060] Where, d ij It represents the distance between control point i and control point j, in meters; n represents the total number of control points; when i=j, d ij = 0; when there is an obstacle between control point i and control point j and they cannot see each other, d ij =∞.

[0061] Then, Prim's algorithm is applied to calculate the minimum spanning tree, and its iterative process is:

[0062] T = {s}; U = V - {s}; {(u, v)=min{(u, v): u∈t, v∈U}; T=T∪{v}; U=U-{v};}

[0063] Where T represents the set of control points included in the minimum spanning tree; s represents the starting control point; V represents the set of all control points; U represents the set of control points not included in the minimum spanning tree; (u, v) represents the edge connecting control point u and control point v; and min{(u, v): u∈T, v∈U} represents the edge with the shortest distance from a control point included in set T to a control point not included in set U. This algorithm constructs the minimum spanning tree by continuously selecting the shortest edges, thus reducing the accumulation of measurement errors.

[0064] The measurement control network optimization equation group includes four main equations: point layout equation, error propagation equation, network strength equation and observation scheme equation.

[0065] The point layout equation is used to determine the optimal location of the measurement control points, which is specifically expressed as follows:

[0066] P = f(B, C, S, R, A);

[0067]

[0068] Where, P = {p1, p2, ..., p n} represents the coordinate set of the measurement control points, p i =(x i ,y i ) is the coordinate of the i-th control point; B={b1,b2,…,b k} represents the plane coordinate matrix of the building, b i =(x bi ,y bi ) is the coordinate of the i-th feature point of the building; C = {c1, c2, ..., c m} represents the layout position matrix of prefabricated hollow square columns, c j =(x cj ,y cj ) is the center coordinate of the jth prefabricated hollow square column; S represents the site constraint matrix, which includes the area where control points can be set and the prohibited area; R = (R min , R max ) represents the instrument viewing range, R min is the minimum effective viewing distance, generally 5m, R max is the maximum effective viewing distance, generally 80m; A represents the instrument accuracy parameter, including angle measurement accuracy and distance measurement accuracy; w ij The weight coefficient representing the importance of control point i to prefabricated hollow square column j is usually determined according to the importance and size of the prefabricated hollow square column and ranges from 0 to 1; d(p i , c j) represents the distance from control point i to prefabricated hollow square column j; λ is the balance coefficient, which is used to balance the influence of the distance between the control point and the prefabricated hollow square column and the distance between the control points, and is generally set to 0.3 to 0.7; g(d(p i , p j ), R min , R max ) is the distance constraint function, when d(p i , p j ) <R min or d(p i , p j )>R max It is a large positive value when , otherwise it is 0. This equation obtains the optimal control point layout by minimizing the sum of the weighted distances from the control points to the prefabricated hollow square columns while considering the distance constraints between the control points.

[0069] The error propagation equation is used to calculate the error transmission law and cumulative effect in the measurement control network. It is specifically expressed as follows:

[0070] Q XX =B(B T W -1 B) -1 B T ;

[0071]

[0072]

[0073] Where Q XX represents the unknown co-factor matrix; B represents the coefficient matrix, which is obtained by linearizing the observation equation; W represents the weight matrix, and the diagonal elements are the weights of each observation value; Indicates the unit weighted error, reflecting the accuracy level of the measuring instrument; q ii represents the diagonal elements of the cofactor matrix; represents the variance of the coordinates of the i-th control point; q ij represents the non-diagonal elements of the cofactor matrix; σ ij represents the covariance of the coordinates of the i-th control point and the j-th control point; ρ ij represents the correlation coefficient; σ α and σ β represents the standard deviation of the error ellipse's semimajor and semiminor axes; γ represents the angle between the semimajor axis and the coordinate axis; and ρ represents the systematic error coefficient of the measuring instrument, typically ranging from 0.8 to 1.2. This equation calculates the cumulative effect of error through covariance propagation and outputs a set of error ellipse parameters, which are used to assess the accuracy of control points.

[0074] The grid strength equation is used to evaluate the effect of the measurement control grid geometry on accuracy, which is expressed as follows:

[0075]

[0076] Where, K represents the overall strength index of the control network; represents the determinant value of the inverse matrix of the cofactor matrix; n represents the number of control points; E represents the average error ellipse flattening, σ αi and σ βi where represents the standard deviation of the semimajor and semiminor axes of the error ellipse at the i-th control point, respectively; H represents the correlation between control points; S represents the overall network strength; w1, w2, and w3 are weight coefficients, satisfying w1 + w2 + w3 = 1, with w1 = 0.5, w2 = 0.3, and w3 = 0.2 being the typical values. This equation comprehensively evaluates the geometric strength of the measurement control network by calculating its overall strength, the flattening of the error ellipse, and the correlation between points. A larger S value indicates a better network strength.

[0077] The observation plan equation is used to generate the optimal measurement sequence and path, which is expressed as follows:

[0078]

[0079] Where x ij is a decision variable, which takes the value of 1 when going directly from control point i to control point j, otherwise it takes the value of 0; c ij represents the cost from control point i to control point j, taking into account factors such as distance, obstacles and observation difficulty; u i is an auxiliary variable used to eliminate subloops; n represents the number of control points. This equation is essentially a linear programming model for solving the traveling salesman problem. The optimal measurement path is obtained by minimizing the total cost of the measurement path while satisfying the constraint that each control point is visited only once.

[0080] In step S05, the pressure calculation formula for the cold-pressed sleeve connection is:

[0081]

[0082] Where, P represents the crimping pressure, the unit is MPa; F represents the crimping force, the unit is N; D o Indicates the outer diameter of the cold-pressed sleeve, in mm; D i Indicates the inner diameter of the cold-pressed sleeve in mm. The crimping force F is provided by hydraulic equipment and is determined by the diameter of the steel bar, generally 1.2 to 1.5 times the tensile strength of the steel bar.

[0083] In step S06, the verticality deviation calculation formula is:

[0084]

[0085] Where δ represents the verticality deviation in mm / m; L1 represents the upper horizontal displacement in mm; L2 represents the lower horizontal displacement in mm; and H represents the column height in m. The verticality deviation control standard is δ ≤ H / 1000 and no greater than 15 mm.

[0086] The formula for calculating the level deviation is:

[0087]

[0088] Where, η represents the level deviation, the unit is mm / m; h max Indicates the highest point elevation, in mm; h min = represents the lowest point elevation in mm; L represents the detection length in m. The levelness deviation control standard is η≤L / 1000 and no more than 10 mm.

[0089] The principles underlying these equations and calculations are primarily based on surveying, graph theory, optimization theory, and structural mechanics. The minimum spanning tree algorithm utilizes a power-sum relationship because error propagation during measurement is closely related to the length and number of observed edges. Selecting the connection method with the shortest total length can effectively reduce error accumulation. The point placement equation utilizes a quadratic function because quadratic functions have good convergence properties in optimization problems and can effectively balance the distance relationship between control points and target points. The error propagation equation utilizes matrix inversion, based on the principle of least squares adjustment, to comprehensively reflect the impact of observation errors on unknowns. The grid strength equation comprehensively considers geometry, error distribution, and inter-point correlation, employing a weighted summation to facilitate adjustment of the importance of each factor. The observation plan equation utilizes a linear programming model, effectively solving path optimization problems under complex constraints. Verticality and horizontality deviation calculations utilize a ratio because deviations are typically proportional to component size, making relative values more appropriate.

[0090] Specifically, the core technical principle of this invention lies in applying the minimum spanning tree algorithm from graph theory to measurement and control network optimization. This algorithm, combined with metrology principles, establishes a systematic set of measurement and control network optimization equations. The minimum spanning tree algorithm essentially finds a subgraph connecting all vertices with the smallest sum of edge weights. In a measurement and control network, by using measurement errors as edge weights, a control network structure with minimal error propagation can be constructed. The measurement and control network optimization equations scientifically evaluate and optimize the control network from multiple dimensions to ensure measurement accuracy and reliability.

[0091] The point placement equation is based on the building layout and component locations, taking into account site constraints and instrument performance parameters. A mathematical optimization model is used to calculate the optimal measurement control point locations, ensuring a more rational distribution of control points and optimal coverage. The error propagation equation utilizes error transfer theory to analyze the propagation of observation errors within the network and quantify the accuracy of each control point. This equation considers factors such as instrument accuracy and atmospheric effects to generate error ellipse parameters that intuitively reflect the accuracy of each point's location.

[0092] The grid strength equation evaluates the geometric strength of the measurement control network. By analyzing factors such as azimuth distribution and side length configuration, it calculates the grid strength index to ensure that the control network structure has good geometric conditions and resists error propagation. The observation plan equation, based on the results of the first three equations and taking into account on-site line-of-sight conditions and obstacle distribution, generates the optimal measurement sequence and path, ensuring an efficient measurement process with minimal error.

[0093] These four equations are interconnected and mutually supportive, forming a complete measurement control network optimization system. The results of this set of equations guide the establishment and observation of the actual measurement control network, significantly improving measurement accuracy and reducing error accumulation. This improved measurement accuracy directly impacts the installation accuracy of prefabricated hollow square columns, fundamentally resolving positioning errors during construction and ensuring the overall geometric accuracy and connection reliability of the structure. This is precisely the principle underlying the core technical solution of the present invention.

[0094] A specific embodiment 1 of the present invention is provided below. The specific implementation of each step in this embodiment 1 is described in detail as follows:

[0095] The specific implementation of step S01 involves comprehensive preparatory work before construction. First, professional technicians conduct in-depth research and analysis of the prefabricated hollow square column construction drawings to understand the design requirements and technical parameters. A detailed construction plan is then compiled, clarifying the construction process flow and establishing quality control standards and inspection methods. Next, materials are prepared, including prefabricated hollow square column components, connecting steel bars, high-strength concrete, and embedded parts. Quality inspections are conducted to ensure that these materials meet design requirements. Finally, hoisting equipment such as tower cranes and mobile cranes are deployed, along with precision measuring instruments such as total stations, levels, and theodolites. This thorough preparation ensures smooth construction, reduces errors and rework, and improves construction efficiency and quality.

[0096] The specific implementation of step S02 is to establish a measurement control network based on the minimum spanning tree algorithm. First, the position coordinates of the prefabricated hollow square columns are determined according to the building plan, and a distance adjacency matrix D is constructed. The matrix is specifically expressed as: Where, d ijIt represents the distance between control point i and control point j, in meters; n represents the total number of control points; when i=j, d ij = 0; when there is an obstacle between control point i and control point j and they cannot see each other, d ij =∞. Then Prim's algorithm is applied to calculate the minimum spanning tree, and its iterative process is: T = {s}; U = V-{s}; {(u, v) = min{(u, v): u∈T, v∈U}; T = T∪{v}; U = U-{v};}, where T represents the set of control points included in the minimum spanning tree; s represents the starting control point; V represents the set of all control points; U represents the set of control points not included in the minimum spanning tree; (u, v) represents the edge connecting control point u and control point v; min{(u, v): u∈T, v∈U} represents selecting the edge with the smallest distance from a control point included in set T to a control point not included in set U. Then, control stakes and leveling points are set. The spacing between control stakes is generally 30 to 50 meters, and the leveling point accuracy is controlled within ±1 mm. A total station is used to stake out the foundation cushion according to the control grid coordinates, marking the edges and axes of prefabricated hollow square columns, with the marking position deviation controlled within ±3 mm. A level is used to measure and mark the installation elevation, with the elevation error controlled within ±2 mm. The optimization equations for the measurement control network include the point layout equation, error propagation equation, network strength equation, and observation scheme equation, as follows: The point layout equation is used to determine the optimal position of the measurement control point, which is expressed as: P = f(B, C, S, R, A); Where, P = {p1, p2, ..., p n} represents the coordinate set of the measurement control points, p i =(x i ,y i ) is the coordinate of the i-th control point; B={b1,b2,…,b k} represents the plane coordinate matrix of the building; C = {c1, c2, ..., c m} represents the prefabricated hollow square column layout position matrix; S represents the site constraint matrix; R = (R min , R max ) represents the instrument’s viewing range; A represents the instrument’s accuracy parameter; w ij represents the weight coefficient; λ is the balance coefficient, which ranges from 0.3 to 0.7. The error propagation equation is used to calculate the error propagation law, which is expressed as: Q XX =B(B T W -1 B) -1 B T ; Where Q XX represents the unknown number co-factor matrix; B represents the coefficient matrix; W represents the weight matrix; represents the unit weighted mean error; represents variance; σ ij represents covariance; ρ ij represents the correlation coefficient; γ represents the angle; ρ represents the systematic error coefficient. The grid strength equation is used to evaluate the control grid geometry and is expressed as: Where K represents the overall strength index; E represents the average error ellipse flattening; H represents the inter-point correlation index; S represents the comprehensive grid strength index; w1, w2, and w3 are weight coefficients, generally taking w1 = 0.5, w2 = 0.3, and w3 = 0.2. The observation plan equation is used to generate the optimal measurement path and is expressed as: Where x ij is the decision variable; c ij Indicates the cost; u i is an auxiliary variable; n represents the number of control points. The purpose of this step is to establish a high-precision measurement control system to ensure the accurate installation position of the prefabricated hollow square column.

[0097] The specific implementation method of step S03 is to conduct a comprehensive inspection of the prefabricated components and connection points before installation. First, check whether the position, quantity, and specifications of the reserved connection dowels for the cast-in-place columns are consistent with the design drawings, with deviations controlled within ±5mm. Then, install the positioning plate on the reserved connection dowels. The positioning plate is made of steel material with a thickness of 8-12mm and is fixed by welding or bolting. It can withstand lateral forces of more than 2000N. Next, check the appearance quality of the prefabricated hollow square columns, including surface flatness, angular integrity, and the presence of defects such as cracks, honeycombs, and rough surfaces. The surface flatness deviation is controlled within 5mm / 2m. Finally, check the model, specifications, and dimensions of the prefabricated hollow square columns for consistency with the design drawings. The cross-sectional dimension error is controlled within ±5mm, and the length error is controlled within ±10mm. The purpose of this step is to ensure that the quality of the prefabricated components and the connection conditions meet the installation requirements through strict inspection, laying the foundation for subsequent construction.

[0098] The specific implementation method of step S04 is to use a lifting tool to install the prefabricated hollow square column. First, a suitable lifting tool is selected. The tool design uses finite element analysis to ensure uniform force and a safety factor of not less than 1.5; then, a lifting point is set on the prefabricated hollow square column. The lifting point position is usually above the center of gravity of the component. A high-strength lifting ring is used with a bearing capacity of not less than 2 times the weight of the component; then the lifting tool is connected to the lifting equipment to check the connection reliability; the prefabricated hollow square column is slowly lifted, and the lifting speed is controlled within 0.5m / min to keep the component stable; finally, the prefabricated hollow square column is aligned with the installation position so that its steel bars are accurately connected to the reserved connecting bars of the cast-in-place column, and the alignment deviation is controlled within ±3mm and the height deviation is controlled within ±2mm. The purpose of this step is to safely position the prefabricated hollow square column through precise lifting technology to ensure installation accuracy and construction safety.

[0099] The specific implementation method of step S05 is to complete the connection between the prefabricated hollow square column and the cast-in-place structure. First, the cold-pressed sleeve connection technology is used to connect the lower connecting steel bars of the prefabricated hollow square column with the reserved connecting dowel bars of the cast-in-place column. The cold-pressed sleeve is made of carbon steel with a wall thickness of not less than 2mm and a length of 3 to 4 times the diameter of the steel bar. The pressure calculation formula of the cold-pressed sleeve is: Where, P represents the crimping pressure, the unit is MPa; F represents the crimping force, the unit is N; D o Indicates the outer diameter of the cold-pressed sleeve, in mm; D i Represents the inner diameter of the cold-pressed sleeve, in mm. Use hydraulic cold extrusion equipment for crimping, with a pressure of 300-400 MPa. The connection quality is then inspected to ensure the cold-pressed sleeve indentations are uniform and free of looseness. Concrete is then poured layer by layer into the precast hollow square column cavity, with a concrete strength grade of no less than C30 and a thickness of 300-500 mm per layer. Vibrate the concrete using a high-frequency vibrator for 20-30 seconds to ensure a density of at least 98%. Finally, cure the concrete at a temperature of 15-25°C for at least 7 days. This step ensures the precast hollow square column integrates with the foundation structure through reliable connection methods and pouring techniques, improving the structural integrity and load-bearing capacity.

[0100] The specific implementation of step S06 is to accurately calibrate the prefabricated hollow square column after installation. First, a high-precision theodolite is used to detect the verticality of the column, measuring from two mutually perpendicular directions with no less than three measurement points; then, the verticality deviation is calculated based on the measurement results. The verticality deviation calculation formula is: Where δ represents the verticality deviation in mm / m; K1 represents the upper horizontal displacement in mm; L2 represents the lower horizontal displacement in mm; and H represents the column height in m. The verticality deviation should be controlled within a range of H / 1000 and no greater than 15 mm (H is the column height). Fine-tune the structure using adjustment tools such as jacks or wedges, keeping the adjustment force within 10% of the component's bearing capacity. Use a high-precision level to calibrate the horizontality. The formula for calculating the horizontality deviation is: Where, η represents the level deviation, the unit is mm / m; h max Indicates the highest point elevation, in mm; h min = represents the lowest point elevation in mm; L represents the inspection length in m. Levelness deviation is controlled within a range of L / 1000 and no greater than 10 mm (L is the column width). Finally, after reaching the designed position, temporary supports are installed with a support angle of 45 to 60 degrees. The support cross-sectional dimensions are determined based on calculations and are generally no less than 100 mm x 100 mm. This step aims to ensure that the installation accuracy of the prefabricated hollow square columns meets regulatory requirements through precise calibration techniques, ensuring the geometric accuracy of the structure.

[0101] The specific implementation method of step S07 is to install a temporary support system to ensure the stability of the prefabricated hollow square column. First, a connecting clip is embedded on the column body of the prefabricated hollow square column. The connecting clip is made of Q345 steel with a thickness of 8 to 12 mm, a bearing capacity of not less than 50 kN, and an embedment depth of not less than 80 mm. Then, a temporary support rod is installed. The support rod material is Q235 steel. The length is determined according to the site conditions, generally 1.2 to 1.5 times the column height, with a diameter of not less than 48 mm and a wall thickness of not less than 3.5 mm. One end of the support rod is connected to the connecting clip using a pin connection method with a pin diameter of not less than 20 mm. The other end is connected to the ground or a completed structure. The ground connection point is fixed with an expansion bolt with a bolt diameter of not less than 16 mm and an embedment depth of not less than 100 mm. The temporary support system is regularly inspected at a frequency of 72 hours per time. The inspection content includes support looseness, deformation, and connection point stability. The purpose of this step is to ensure the stability of the prefabricated hollow square columns after installation and during subsequent construction through a reliable temporary support system to prevent displacement or tilting due to external forces.

[0102] The specific implementation of step S08 is to strengthen the connection nodes between the prefabricated hollow square columns and the cast-in-place structure. First, the connection nodes are visually inspected, including the concrete density, steel bar connection status, and embedded parts position. Then, according to the design requirements, the connection nodes are reinforced with steel bars or steel plates. The diameter of the reinforcement steel bars is not less than 12mm, the spacing is 100-150mm, the thickness of the reinforcement steel plates is not less than 8mm, and the contact area with the concrete is not less than 200cm. 2Next, waterproof the connection points using a flexible waterproofing material, either applied or wrapped. The waterproofing layer should be at least 2mm thick, with a tensile strength of at least 1.5MPa and an elongation of at least 300%. Finally, inspect the waterproofing to ensure there are no leaks. This step aims to improve the reliability and durability of the connection between the precast hollow square columns and the cast-in-place structure by strengthening the connection points with reinforced and waterproofed measures.

[0103] The specific implementation of step S09 is to conduct a comprehensive acceptance inspection after the installation of the prefabricated hollow square column. First, after the concrete has finally set (generally 2-3 days after pouring), an appearance inspection is carried out. The inspection content includes whether there are quality defects such as cracks, honeycombs, and pitting on the surface. The crack width must not exceed 0.2mm, and the crack depth must not exceed the thickness of the protective layer. Then, a dimensional inspection is carried out to check the cross-sectional dimensions, height, verticality, and horizontality. The cross-sectional dimension deviation is controlled within ±5mm, the height deviation is controlled within ±10mm, the verticality deviation is controlled within the range of H / 1000 and no more than 15mm, and the horizontality deviation is controlled within the range of L / 1000 and no more than 10mm. Then, a connection inspection is carried out. The inspection content includes the quality of the cold-pressed sleeve connection, the connection status of the embedded parts, and the density of the concrete pouring. Non-destructive testing methods such as ultrasonic testing are used to assess the connection strength. The connection strength must not be less than 95% of the design strength. Finally, an acceptance report is compiled to record the acceptance results and the corresponding treatment measures. The purpose of this step is to ensure that the installation quality of the prefabricated hollow square column meets the design and specification requirements through a strict acceptance procedure, thereby ensuring the quality of the project.

[0104] Among them, the measurement control network optimization equation group includes point layout equations, error propagation equations, network strength equations, and observation scheme equations. These equation groups work together to establish the measurement control network in step S02. The point layout equation is based on the least squares principle. By minimizing the sum of the weighted distances from the control points to the prefabricated hollow square columns, while considering the distance constraints between the control points, the optimal control point layout is obtained. The error propagation equation is based on the error propagation law. The error cumulative effect is calculated through covariance propagation, and the error ellipse parameter set is output to evaluate the accuracy of the control points. The network strength equation is based on the theory of the influence of geometric shape on accuracy. By calculating the overall strength of the control network, the error ellipse flattening and the correlation between points, the geometric strength of the measurement control network is comprehensively evaluated. The observation scheme equation is based on optimization theory. By minimizing the total cost of the measurement path and satisfying the constraint that each control point is only visited once, the optimal measurement path is obtained.

[0105] The minimum spanning tree algorithm, applied in step S02, leverages the principle of minimum spanning trees in graph theory to construct a tree structure connecting all control points by continuously selecting the shortest edges, thereby reducing measurement error accumulation. This algorithm is relevant to the establishment of a measurement control network because error propagation during measurement is closely related to the length and number of observed edges. Selecting the connection method with the shortest total length can effectively reduce error accumulation and improve measurement accuracy.

[0106] The positioning plate used in step S03 prevents the reserved connecting steel bars from shifting during subsequent construction, improving the positioning accuracy of the steel bars and reducing construction errors. The positioning plate is designed based on mechanical principles and can withstand lateral forces during construction, ensuring the stable position of the connecting bars.

[0107] The cold-pressed sleeve, used in step S05, tightly connects the sleeve to the rebar through a cold extrusion process, achieving a reliable connection between the rebar ends. This cold-pressed sleeve connection technology, based on the principle of plastic deformation of the material, uses high pressure to mechanically interlock the sleeve and rebar, resulting in high connection strength and fast construction speed.

[0108] The connection clip in step S07 is used as a device embedded in the prefabricated hollow square column to connect with the temporary support rod. The design of the connection clip conforms to the principles of mechanics and has sufficient strength and rigidity to ensure the stability of the temporary support system.

[0109] The precast hollow square column design is a hollow square structure made of high-strength concrete, with an internal steel cage. Embedded components are distributed around the perimeter for connection to the upper and lower structures, and holes are reserved on the sides for routing water and electricity lines. This design, based on the principles of structural mechanics, meets load-bearing requirements while reducing deadweight, resulting in advantages such as light weight, high strength, and easy construction.

[0110] It should be noted that the variables involved in the present invention are explained in detail as shown in Table 1 below.

[0111] Table 1 Variable explanation table

[0112]

[0113] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be covered by the scope of protection of the present invention.

Claims

1. A construction method for prefabricated hollow square columns, characterized in that: include: Conduct construction preparation work; A minimum spanning tree measurement control network is established according to the plan layout of the building, and control piles and leveling points are set. The measurement control network uses a minimum spanning tree algorithm to optimize the layout of control points. The optimal connection path is calculated through the control point position coordinate matrix and the distance weight matrix to reduce the accumulation of measurement errors. The prefabricated hollow square column edge lines and control lines are marked on the foundation cushion using a total station, and the installation elevation is measured and marked with a level; positioning plates are installed to prevent the connection steel bars from deviating; prefabricated hollow square columns are installed; prefabricated hollow square columns are connected to cast-in-place columns; the position of prefabricated hollow square columns is corrected; temporary supports are installed; connection nodes are checked; and prefabricated hollow square columns are accepted. The minimum spanning tree measurement control network layout is calculated using the measurement control network optimization equation group.

2. The construction method of a prefabricated hollow square column according to claim 1, characterized in that: The measurement control network optimization equation group includes point layout equations, error propagation equations, network strength equations, and observation scheme equations.

3. The construction method of a prefabricated hollow square column according to claim 2, characterized in that: The point layout equation is used to determine the optimal position of the measurement control points. The input includes the building plane coordinate matrix, the prefabricated hollow square column layout position matrix, the site constraint matrix, the instrument sight range, and the instrument accuracy parameters. The output is a set of measurement control point coordinates.

4. The construction method of a prefabricated hollow square column according to claim 3, characterized in that: The error propagation equation is used to calculate the error transmission law and cumulative effect in the measurement control network. The input includes the coordinate set of the measurement control point, the number of observation edges, the instrument angle measurement accuracy, the instrument distance measurement accuracy, and the atmospheric influence factor. The output is the error ellipse parameter set.

5. The construction method of a prefabricated hollow square column according to claim 4, characterized in that: The grid strength equation is used to evaluate the impact of the geometric shape of the measurement control network on accuracy. The input includes the measurement control point coordinate set, observation plan matrix, error ellipse parameter set, azimuth distribution, and side length distribution. The output is the grid strength index.

6. The construction method of a prefabricated hollow square column according to claim 5, characterized in that: The observation scheme equation is used to generate the optimal measurement sequence and path. The input includes the measurement control point coordinate set, the number of instrument stations, the observation edge weight, the obstacle distribution, and the line-of-sight condition. The output is the measurement observation sequence and path diagram.

7. The construction method of a prefabricated hollow square column according to claim 6, characterized in that: The steps of installing the positioning plate to prevent the connection steel bars from being displaced include: inspecting the reserved connection dowels of the cast-in-place columns, installing the positioning plate to prevent the connection steel bars from being displaced, inspecting the appearance of the prefabricated hollow square columns to ensure there are no quality defects, and checking whether the model specifications are consistent with the design drawings.

8. The construction method of a prefabricated hollow square column according to claim 7, characterized in that: The steps of installing the prefabricated hollow square column include: using a lifting tool to install the prefabricated hollow square column in a designated position, ensuring that the lifting tool is firmly installed and evenly stressed, and slowly lifting the prefabricated hollow square column to the installation position so that it is aligned with the reserved connecting dowels and positioning plates; the prefabricated hollow square column is a hollow square structure made of high-strength concrete, with a steel cage arranged inside, embedded parts distributed around it for connection with the upper and lower structures, and reserved holes arranged on the side for passing water and electricity pipelines.

9. The construction method of a prefabricated hollow square column according to claim 8, characterized in that: The steps of connecting the prefabricated hollow square column and the cast-in-place column include: connecting the lower connecting steel bars of the prefabricated hollow square column with the reserved connecting dowel bars of the cast-in-place column by using a cold-pressed sleeve method to ensure that the connection parts are firm and reliable, and then pouring concrete in layers in the cavity of the hollow square column and vibrating it to make it dense.

10. The construction method of a prefabricated hollow square column according to claim 9, characterized in that: The positioning plate is a fixing device installed on the reserved connecting dowel bar, which is used to prevent the reserved connecting steel bars from being displaced during the subsequent construction process, improve the positioning accuracy of the steel bars, and reduce construction errors; the cold-pressed sleeve is a mechanical connection device for steel bars, which tightly connects the sleeve and the steel bars through a cold extrusion process to achieve reliable connection of the steel bar ends; the connecting clip is a device embedded in the prefabricated hollow square column and connected to the temporary support rod.

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