A design method and system for a connecting joint of a fabricated modular building

Abstract

The application discloses a kind of connecting node design method and system of fabricated modular building, including identifying fabricated module contact area and dividing connecting node group, determining the quantity and position of connecting member of each connecting node, determining the first target stiffness of each connecting node group, the second target stiffness is obtained by using point group stiffness optimization objective function optimization, construct connecting node state prediction model, obtain initial stiffness target value by reducing second target stiffness, adjusting connecting node controllable parameter according to initial stiffness target value and connecting node state prediction model, build fabricated modular building, calculate cumulative error and cumulative adaptive tolerance limit, compare data Real-time fine-tuning connecting node part controllable parameter.The method not only can improve the efficiency and accuracy of the connecting node design of fabricated modular building, but also has good explainability, which can be directly applied to the connecting node design system of fabricated modular building.

Description

Technical Field

[0001] This invention relates to the field of building engineering technology, and in particular to a design method and system for connection nodes in prefabricated modular buildings. Background Technology

[0002] Prefabricated modular buildings, with their advantages of high factory prefabrication rates, short on-site construction cycles, and low environmental pollution, have become an important direction for the development of the construction industry. Among these, connection nodes not only bear vertical load transfer but also resist horizontal seismic and wind loads. Their stiffness matching, load-bearing reliability, and construction tolerance directly determine the overall safety and durability of the building. Therefore, establishing scientific, efficient, and error-tolerant connection node design methods is of great significance for promoting the application of modular buildings in high-rise buildings.

[0003] However, existing technologies still have significant limitations: First, existing design methods often focus on isolated analyses of single nodes, lacking consideration of the synergistic effects of node groups, leading to uneven stiffness distribution among different types of nodes, which easily causes stress concentration and excessive inter-story drift angles. Simultaneously, traditional design relies on repeated calculations using finite element software, resulting in long design cycles, low efficiency, and a lack of quantitative relationship between node stiffness and construction errors. It typically employs a static control strategy with fixed allowable errors, failing to dynamically adjust design parameters based on actual construction accuracy. Furthermore, existing node optimization only focuses on initial mechanical properties, lacking adaptive design for the accumulation of errors during construction, resulting in over-design of some nodes and insufficient safety reserves for others. Therefore, this invention proposes a connection node design method and system for prefabricated modular buildings. This method achieves stiffness matching through a point group stiffness optimization objective function, constructs a predictive model through finite element analysis, and introduces stiffness reduction and real-time error feedback mechanisms. It effectively solves the technical problems of uneven node stiffness distribution, low design efficiency, and difficulty in dynamically compensating for construction errors, significantly improving the scientific and economic aspects of modular building structural design. Summary of the Invention

[0004] The purpose of this invention is to provide a design method and system for connection nodes in prefabricated modular buildings.

[0005] To achieve the above objectives, the present invention is implemented according to the following technical solution: This invention includes the following steps: A 3D building model is generated based on architectural drawings, and the contact areas of prefabricated modules are identified. Connection node groups are divided according to the functional location of the building, and the number and location of connection components for each connection node are determined. The first target stiffness of each group of connecting nodes is determined based on the building's functional location and structure. The second target stiffness is obtained by optimizing the first target stiffness using the point group stiffness optimization objective function. Finite element analysis is performed by setting different external states and controllable parameter combinations for the connection nodes, and a connection node state prediction model is constructed based on the finite element analysis results. The initial stiffness target value is obtained by reducing the second target stiffness, and the controllable parameters of the connection node are adjusted according to the initial stiffness target value and the connection node state prediction model. Prefabricated modular buildings are constructed based on the controllable parameters of the connection nodes. Construction errors are statistically analyzed and cumulative errors are calculated in real time. Adaptive allowable error limits are calculated based on the building target reliability. Based on the comparison results of cumulative error and cumulative adaptive allowable error limits, the controllable parameters of the connection nodes are finely adjusted in real time. The connection node group includes corner node group, edge node group and internal node group; The first target stiffness and the second target stiffness are theoretical stiffnesses; The finite element analysis results include initial stiffness, nodal bending moments, and ultimate bending moments of the connected nodal group; The external state includes the overall building specifications, the specifications of local prefabricated components, the connection type, and the contact area; the connection type is associated with the connection node type. The controllable parameters include the number, location, size, strength grade, and preload of the connecting components; The state of the connection node includes initial stiffness and node bending moment; The construction errors include manufacturing errors and installation errors.

[0006] Furthermore, the method for determining the number and location of connecting components at each connecting node includes: Architectural drawings are input into BIM software to generate a 3D building model. The software identifies the contact areas of each prefabricated module as connection nodes. The type of connection node is determined according to the functional location of the building, and connection node groups are divided. The connection node groups include corner node groups, edge node groups, and internal node groups. Determine the standard connection form for different connection nodes; the standard connection form is associated with the type of connection node group, including the standard contact area, the standard number of connection components, and the standard arrangement of connection components; Calculate the ratio of the actual contact area of ​​each connection node of the prefabricated modular building to the corresponding standard contact area. Determine the number and location of the corresponding connection components based on the contact area ratio. The number of connection components for each connection node of the prefabricated modular building to be designed is the product of the corresponding contact area ratio and the standard number. The arrangement of the connection components for each connection node of the prefabricated modular building to be designed is consistent with the corresponding standard arrangement.

[0007] Furthermore, the method for obtaining the second target stiffness includes: The first target stiffness of each group of connecting nodes is determined based on the building's functional location and structure, expressed as follows: ; in for The first target stiffness of the class connection node, This refers to the design value of the floor shear force. For floor height, This is the limit value for the inter-story drift angle. for Number of class-connected nodes For the first The distance from each point to the center of rigidity of the structure. for Adjustment coefficient for class-connected nodes; The first objective stiffness is optimized using a point group stiffness optimization objective function until the stiffness optimization objective function is minimized. The corresponding objective stiffness is then output as the second objective stiffness, expressed as: ; ; in The objective function for optimizing the stiffness of the point group is... , , Assign weights to the target. The stiffness matching index. The total mass of the structure. This is the upper limit of quality. For the basic period of the structure, For periodic limits, For the number of floors, , For stiffness matching degree weight, For the first The coefficient of variation of stiffness of all connected nodes in the layer. For the first Maximum stiffness deviation rate of the layer.

[0008] Furthermore, the method for constructing the connection node state prediction model includes: Orthogonal experimental design was carried out according to the connection node type, external state and controllable parameters. Different parameter combinations were generated for finite element analysis. The initial stiffness, nodal bending moment and ultimate bending moment of each node were extracted. The minimum value of the ultimate bending moment of the same type of connection node was taken as the ultimate bending moment of the connection node group. A three-parameter power function model is fitted to the initial stiffness, nodal moments, and ultimate bending moments of the connected node group to obtain the nodal moment-initial stiffness mapping relationship, expressed as: ; in for Nodal bending moment of the connecting nodes, for Initial stiffness of the connection node, For the corner of the connection point, For reference, plastic rotation angle, for Connecting nodes to corresponding node types Ultimate bending moment of the group of connecting nodes; The node types, external states, controllable parameters, and initial stiffness from the finite element analysis results are combined into a comprehensive set. The comprehensive set is then randomly divided into a training set and a test set in a 6:4 ratio. The training set is used to train the connection node state prediction model, and the test set is used to evaluate the model performance. The connection node state prediction model includes an input layer, a feature processing layer, an initial stiffness prediction layer, a node bending moment prediction layer, and an output layer. The feature processing layer uses an attention mechanism to fuse node type, external state, and controllable parameters to obtain connection node features. The initial stiffness prediction layer uses a gradient boosting tree algorithm to establish a nonlinear mapping relationship between connection node features and initial stiffness, and predicts the initial stiffness of each connection node. The node bending moment prediction layer embeds a node bending moment-initial stiffness mapping relationship and predicts the corresponding node bending moment of each connection node based on the prediction results of the initial stiffness prediction layer.

[0009] Furthermore, the method for adjusting the controllable parameters of the connection node includes: The stiffness reduction factor for each connection node is calculated based on the allowable cumulative error of the building. The initial stiffness target value is obtained by reducing the second target stiffness, as expressed by: ; in This is the stiffness reduction factor. This is the error influence coefficient. To allow for cumulative errors in construction, The height of the local column section at the connection node. To determine the bending stiffness of the local beam section at the connection node, For elastic modulus, For effective inertial torque, The second target stiffness corresponds to the connection node. For the local beam span of the connection node; The connection node type, external state, and controllable parameters of the prefabricated modular building to be designed are input into the connection node state prediction model to obtain the initial stiffness prediction value and the node bending moment prediction value of each connection node. The values ​​are compared with the corresponding initial stiffness target value. When the initial stiffness prediction value is less than the corresponding initial stiffness target value or the node bending moment prediction value is greater than the corresponding node bending moment threshold, the controllable parameters of the corresponding connection node are adjusted, and the initial stiffness prediction value and the node bending moment prediction value are updated again by inputting them into the connection node state prediction model. The process continues until the initial stiffness prediction value and the node bending moment prediction value of all nodes meet the requirements.

[0010] Furthermore, the method for fine-tuning the controllable parameters of the connection node includes: Prefabricated modular buildings are constructed based on controllable parameters of connection nodes. Construction errors are statistically analyzed in real time and cumulative errors are calculated. Adaptive allowable error limits are calculated based on the target reliability of the building. The expression is as follows: ; ; in No. The cumulative error of the layer, For the first Layer connection nodes, To account for manufacturing errors, Due to installation error, This is the interlayer error correlation coefficient. This refers to the allowable error limit for a single connection point. This is the error influence coefficient. , , To correspond to the local column section height, local beam section bending stiffness, and local beam span of the connection node, For elastic modulus, For effective inertial torque, It is the inverse function of the standard normal distribution. This is the minimum reduction factor. For target reliability indicators; The adaptive tolerance error limits of all connection nodes on the same layer are summed to obtain the cumulative adaptive tolerance error limit. The cumulative error is compared with the cumulative adaptive tolerance error limit. When the cumulative error exceeds the cumulative adaptive tolerance error limit, the controllable parameters of the connection node are finely adjusted during the construction of the next layer of prefabricated modules. The controllable parameters include the size of the connection component, the strength grade, and the preload.

[0011] Secondly, a connection node design system for prefabricated modular buildings includes: Connection Node Determination Module: Used to generate a 3D building model based on architectural drawings and identify the contact area of ​​prefabricated modules, divide the connection node group according to the building's functional location, and determine the number and location of the connection components of each connection node; Target stiffness determination module: used to determine the first target stiffness of each group of connected nodes based on the building's functional location and structure, and to optimize the first target stiffness using a point group stiffness optimization objective function to obtain the second target stiffness; Node state prediction module: used to set different external states and controllable parameter combinations of connected nodes for finite element analysis, and to construct a connected node state prediction model based on the finite element analysis results; Controllable parameter design module: used to reduce the second target stiffness to obtain the initial stiffness target value, and adjust the controllable parameters of the connection node according to the initial stiffness target value and the connection node state prediction model; Controllable parameter fine-tuning module: used to build prefabricated modular buildings based on the controllable parameters of the connection nodes, to count construction errors in real time and calculate cumulative errors, to calculate adaptive allowable error limits based on the building target reliability, and to fine-tune the controllable parameters of the connection nodes in real time based on the comparison results of cumulative errors and cumulative adaptive allowable error limits.

[0012] The beneficial effects of this invention are: This invention relates to a design method and system for connection nodes in prefabricated modular buildings. Compared with existing technologies, this invention has the following technical advantages: This invention divides the connecting node groups according to the functional location of the building and adopts the objective function of point group stiffness optimization based on stiffness matching index, which effectively reduces the stiffness variation coefficient within the node group, solves the problem of sudden change in inter-story stiffness caused by traditional single node design, makes the inter-story drift angle distribution of the structure more uniform, and improves the overall seismic performance of the building. This invention decomposes the characteristics of the connection node into external states and controllable parameters, generates different parameter combinations through orthogonal experimental design, obtains training data through finite element analysis, and constructs a connection node state prediction model, thereby achieving accurate prediction of the initial stiffness and bending moment of the node. This invention quantitatively considers the weakening effect of construction errors on node stiffness through stiffness reduction factor, and considers the strength constraint of 0.8 times the ultimate bending moment of the connecting node group, and establishes a dual threshold control system that simultaneously meets stiffness requirements and strength reserves. This invention calculates cumulative error and cumulative adaptive allowable error limits during construction. When the cumulative error exceeds the limit, the connection node parameters are finely adjusted to dynamically improve the node stiffness, compensating for the stiffness loss caused by error accumulation. This avoids the inefficient mode of rework when errors exceed the standard in traditional methods, ensuring the structural safety and reliability of modular buildings under construction deviations. Thus, a complete design-construction integrated technology closed loop is constructed, realizing the dynamic matching between design goals and actual construction results. This provides technical support for the intelligent construction of modular buildings and has positive significance for promoting the integrated development of building industrialization and digitalization. Attached Figure Description

[0013] Figure 1 This is a flowchart illustrating the steps of a connection node design method for prefabricated modular buildings according to the present invention. Detailed Implementation

[0014] The present invention will be further described below through specific embodiments. The illustrative embodiments and descriptions herein are used to explain the present invention, but are not intended to limit the present invention.

[0015] The present invention discloses a method and system for designing connection nodes in prefabricated modular buildings, comprising the following steps: like Figure 1 As shown, this embodiment includes the following steps: A 3D building model is generated based on architectural drawings, and the contact areas of prefabricated modules are identified. Connection node groups are divided according to the functional location of the building, and the number and location of connection components for each connection node are determined. The first target stiffness of each group of connecting nodes is determined based on the building's functional location and structure. The second target stiffness is obtained by optimizing the first target stiffness using the point group stiffness optimization objective function. Finite element analysis is performed by setting different external states and controllable parameter combinations for the connection nodes, and a connection node state prediction model is constructed based on the finite element analysis results. The initial stiffness target value is obtained by reducing the second target stiffness, and the controllable parameters of the connection node are adjusted according to the initial stiffness target value and the connection node state prediction model. Prefabricated modular buildings are constructed based on the controllable parameters of the connection nodes. Construction errors are statistically analyzed and cumulative errors are calculated in real time. Adaptive allowable error limits are calculated based on the building target reliability. Based on the comparison results of cumulative error and cumulative adaptive allowable error limits, the controllable parameters of the connection nodes are finely adjusted in real time. The connection node group includes corner node group, edge node group and internal node group; The first target stiffness and the second target stiffness are theoretical stiffnesses; The finite element analysis results include initial stiffness, nodal bending moments, and ultimate bending moments of the connected nodal group; The external state includes the overall building specifications, the specifications of local prefabricated components, the connection type, and the contact area; the connection type is associated with the connection node type. The controllable parameters include the number, location, size, strength grade, and preload of the connecting components; The state of the connection node includes initial stiffness and node bending moment; The construction errors include manufacturing errors and installation errors.

[0016] In this embodiment, the method for determining the number and location of connecting components at each connecting node includes: Architectural drawings are input into BIM software to generate a 3D building model. The software identifies the contact areas of each prefabricated module as connection nodes. The type of connection node is determined according to the functional location of the building, and connection node groups are divided. The connection node groups include corner node groups, edge node groups, and internal node groups. Determine the standard connection form for different connection nodes; the standard connection form is associated with the type of connection node group, including the standard contact area, the standard number of connection components, and the standard arrangement of connection components; Calculate the ratio of the actual contact area of ​​each connection node of the prefabricated modular building to the corresponding standard contact area. Determine the number and location of the corresponding connection components based on the contact area ratio. The number of connection components for each connection node of the prefabricated modular building to be designed is the product of the corresponding contact area ratio and the standard number. The arrangement of the connection components for each connection node of the prefabricated modular building to be designed is consistent with the corresponding standard arrangement. In actual assessment, taking the connection node design of a multi-story steel structure modular office building as an example, the seismic fortification intensity is 8 degrees, the design service life is 50 years, the steel frame-braced structure is used, the modular units adopt box-type modules, there are 6 floors above ground, the total height is 23.4m, the standard floor height is 3.9m, and the standard module plan dimensions are 6.0m (span) × 4.2m (depth). Import the architectural drawings (DWG format) into Revit, locate the grid system using the "Link CAD" function, create modular frame units using the "Structural Columns" and "Structural Frames" family templates, write a node recognition script using the Dynamo module, extract the boundary boxes of all modular units, detect the spatial intersection of adjacent modules using Geometry.Intersect, start the "Clash Detection" function of Navisworks Manage, set the tolerance to 5mm, and automatically identify the contact areas between modules, including corner contact - the intersection area of ​​corner columns of adjacent modules (double-axis intersection, located at the four corners and concave and convex corners of the building), edge contact - the alignment area of ​​edge columns of adjacent modules on the same floor (single-axis extension, located on the outer perimeter of the building, not at the corners), and internal contact - the column end docking area of ​​upper and lower level modules (vertical force transmission, located in the middle of the building). Based on the spatial functional location of the module in the building (planar location + vertical force transmission path), a unique mapping rule is established with the connection node type, that is, the corner contact area corresponds to the corner node group, the edge contact area corresponds to the edge node group, and the internal contact area corresponds to the internal node group. The corner fitting connection nodes are applied at corner node groups (four corners of the building, both sides of the seismic joint, and concave and convex corners of the plane). Three-dimensional corner fittings are set at the corners of the modules for bolt fixing (pre-set bolt holes on each surface). The standard contact area is 1.2 times the corner column cross-sectional size, and 8 high-strength bolts are arranged symmetrically in double rows. The column end connection nodes are applied at column-to-column joints in the edge node groups and internal node groups. They are connected by end plate bolts (20mm thick end plates are welded to the upper and lower module column ends, with pre-reserved bolt holes, and connected by 4 through-long bolts arranged symmetrically at the four corners). The standard contact area is the column cross-sectional area. The beam end connection points are applied at beam-to-beam splicing parts in the internal node groups and beam ends connected to edge columns in the edge node groups. They are connected by end plate bolts (cantilever beams and internal beams are spliced ​​by 12mm thick connecting plates on the upper and lower flanges and 10mm thick web connecting plates. The connecting plates are clamped to the beam flanges by high-strength bolts). 4 high-strength bolts are arranged in double rows on the flange side and 6 high-strength bolts are arranged equidistantly in a single row on the web. Taking the determination of the number and location of connecting components at the corner node of axis A-1 (southwest corner of the building, the intersection of the first and second floor modules) as an example, corner fittings are used accordingly. The actual effective contact area of ​​the corner fittings at the corner of axis A-1 is 0.078m². 2 The number of connecting components at the corner joint of shaft A-1 is determined by calculating the contact area ratio. However, at least four bolts are needed to form a force couple at the corner joint. Therefore, two bolts are arranged on each side flange of the corner joint of shaft A-1 (which is mechanically equivalent to the standard quincunx arrangement). Similarly, the number and position of connecting components at all connecting joints are determined in the same way as above (the end plate thickness and bolt length are fixed, and the length of the connecting plate is consistent with the change in the number of connecting components).

[0017] In this embodiment, the method for obtaining the second target stiffness includes: The first target stiffness of each group of connecting nodes is determined based on the building's functional location and structure, expressed as follows: ; in for The first target stiffness of the class connection node, This refers to the design value of the floor shear force. For floor height, This is the limit value for the inter-story drift angle. for Number of class-connected nodes For the first The distance from each point to the center of rigidity of the structure. for Adjustment coefficient for class-connected nodes; The first objective stiffness is optimized using a point group stiffness optimization objective function until the stiffness optimization objective function is minimized. The corresponding objective stiffness is then output as the second objective stiffness, expressed as: ; ; in The objective function for optimizing the stiffness of the point group is... , , Assign weights to the target. The stiffness matching index. The total mass of the structure. This is the upper limit of quality. For the basic period of the structure, For periodic limits, For the number of floors, , For stiffness matching degree weight, For the first The coefficient of variation of stiffness of all connected nodes in the layer. For the first Maximum stiffness deviation rate of the layer; In actual assessment, taking the connection node design of a 6-story modular steel structure office building as an example, the standard floor height is 3.9m, and the inter-story drift angle limit is... The adjustment coefficients for the corner node group, edge node group, and internal node group are taken as 1.35, 1.10, and 0.85, respectively. The shear design values ​​for each floor decrease sequentially from the bottom to the top floor as 2800 / 2450 / 2100 / 1750 / 1400 / 1050 kN. The first target stiffness of each connecting node group on the bottom floor is calculated to be 18.17 × 10⁻⁶ kN. 3kN·m / rad, 10.69×10 3 kN·m / rad, 15.26×10 3 kN·m / rad; The target allocation weights are set to 0.5 / 0.3 / 0.2, the stiffness matching weights are set to 0.6 / 0.4, the mass limit is set to 850t, and the period limit is set to 0.9s. The stiffness variation coefficient and maximum stiffness deviation rate of all connection nodes on each floor are calculated in layers, and the stiffness optimization objective function is calculated. The first target stiffness of each floor is adjusted (with the goal of reducing the stiffness variation coefficient and improving SMI, increasing the stiffness of edge nodes and decreasing the stiffness of corner nodes). The stiffness optimization objective function and the adjustment of the first target stiffness are repeated until the stiffness optimization objective function is minimized, at which point the target stiffness optimization is stopped, and the corresponding target stiffness is output as the second target stiffness. The second target stiffness is set according to the connection node groups on each floor. Taking the bottom floor as an example, the second target stiffness of each connection node group is: 16.2 × 10⁻⁶. 3 kN·m / rad, 13.8×10 3 kN·m / rad, 14.50×10 3 kN·m / rad.

[0018] In this embodiment, the method for constructing a connection node state prediction model includes: Orthogonal experimental design was carried out according to the connection node type, external state and controllable parameters. Different parameter combinations were generated for finite element analysis. The initial stiffness, nodal bending moment and ultimate bending moment of each node were extracted. The minimum value of the ultimate bending moment of the same type of connection node was taken as the ultimate bending moment of the connection node group. A three-parameter power function model is fitted to the initial stiffness, nodal moments, and ultimate bending moments of the connected node group to obtain the nodal moment-initial stiffness mapping relationship, expressed as: ; in for Nodal bending moment of the connecting nodes, for Initial stiffness of the connection node, For the corner of the connection point, For reference, plastic rotation angle, for Connecting nodes to corresponding node types Ultimate bending moment of the group of connecting nodes; The node types, external states, controllable parameters, and initial stiffness from the finite element analysis results are combined into a comprehensive set. The comprehensive set is then randomly divided into a training set and a test set in a 6:4 ratio. The training set is used to train the connection node state prediction model, and the test set is used to evaluate the model performance. The connection node state prediction model includes an input layer, a feature processing layer, an initial stiffness prediction layer, a node bending moment prediction layer, and an output layer. The feature processing layer uses an attention mechanism to fuse node type, external state, and controllable parameters to obtain connection node features. The initial stiffness prediction layer uses a gradient boosting tree algorithm to establish a nonlinear mapping relationship between connection node features and initial stiffness, and predicts the initial stiffness of each connection node. The node bending moment prediction layer embeds a node bending moment-initial stiffness mapping relationship and predicts the corresponding node bending moment of each connection node based on the prediction results of the initial stiffness prediction layer.

[0019] In this embodiment, the method for adjusting the controllable parameters of the connection node includes: The stiffness reduction factor for each connection node is calculated based on the allowable cumulative error of the building. The initial stiffness target value is obtained by reducing the second target stiffness, as expressed by: ; in This is the stiffness reduction factor. This is the error influence coefficient. To allow for cumulative errors in construction, The height of the local column section at the connection node. To determine the bending stiffness of the local beam section at the connection node, For elastic modulus, For effective inertial torque, The second target stiffness corresponds to the connection node. For the local beam span of the connection node; The connection node type, external state, and controllable parameters of the prefabricated modular building connection nodes to be designed are input into the connection node state prediction model to obtain the initial stiffness prediction value and node bending moment prediction value of each connection node. The values ​​are compared with the corresponding initial stiffness target value. When the initial stiffness prediction value is less than the corresponding initial stiffness target value or the node bending moment prediction value is greater than the corresponding node bending moment threshold, the controllable parameters of the corresponding connection node are adjusted, and the initial stiffness prediction value and node bending moment prediction value are updated again by inputting them into the connection node state prediction model. The process continues until the initial stiffness prediction value and node bending moment prediction value of all nodes meet the requirements. In actual evaluation, the stiffness reduction factor of each connection node is determined by the local column section height, local beam section bending stiffness and local beam span of the connection node. Therefore, each connection node has a unique corresponding stiffness reduction factor. The initial stiffness target value is obtained by multiplying the stiffness reduction factor by the second target stiffness. Similarly, each connection node has a unique corresponding initial stiffness target value. In addition, the node bending moment threshold of each connection point is taken as 0.8 times the ultimate bending moment of the corresponding connection node group. The second target stiffness (16.2 × 10⁻¹⁰) is based on the corner node (southwest corner of the building, corner node group) on axis A-1 of the first floor. 10Taking the reduction of N·mm / rad as an example, with the allowable cumulative error of 120mm and the error influence coefficient of 4, the local column section height involved in the error influence coefficient of the contact area where the connection node is located is 300mm, and the local beam section bending stiffness is 2.52×10 13 N·mm 2 The span of the local beam is 6000mm, and the corresponding reduction factor is calculated to be 0.858. The initial stiffness target value of the corner node of axis A-1 on the first floor is 13.9×10. 3 kN·m / rad; The external state (overall building specifications, specifications of local prefabricated components, connection type, contact area) and controllable parameters (number, location, size, strength grade, and preload of connecting components) of the corner node on axis A-1 of the first floor are input into the connection node state prediction model to obtain the initial stiffness prediction value of 12.35 × 10⁻⁶. 3 The predicted bending moment at the nodes is 338 kN·m / rad; the contact area involves column members (300×300×12mm box section, material Q355B, with connecting end plates at the column ends) and beam members (H400×200×8×13mm hot-rolled H-beams, material Q355B), with a contact area of ​​108000 mm². 2 The bolts are M24 grade 10.9 high-strength bolts, and the end plates are made of 20mm thick Q355B steel with dimensions of 350mm×350mm, without preload. Data comparison revealed an initial stiffness prediction value of 12.35 × 10⁻⁶. 3 The kN·m / rad ratio is less than the initial stiffness target value of 13.9 × 10⁻⁶. 3 The predicted value of the node bending moment is 338 kN·m, which is greater than the node bending moment threshold of 360 kN·m. The controllable parameters are adjusted, and the connection node state prediction model is re-entered to update the initial stiffness prediction value and the node bending moment prediction value. This process continues until the initial stiffness prediction value and the node bending moment prediction value of all nodes meet the requirements. At this time, the controllable parameters of the connection node are: 6 M24 grade 10.9 high-strength friction bolts are used, arranged in double rows / 3 bolts per row / quincunx pattern, and the end plate is 22mm thick 350mm×350mm Q355B steel with no preload. Similarly, controllable parameters for all connection nodes of prefabricated modular buildings are designed according to the above method, and prefabricated components are produced according to the design results.

[0020] In this embodiment, the method for fine-tuning the controllable parameters of the connection node includes: Prefabricated modular buildings are constructed based on controllable parameters of connection nodes. Construction errors are statistically analyzed in real time and cumulative errors are calculated. Adaptive allowable error limits are calculated based on the target reliability of the building. The expression is as follows: ; ; in No. The cumulative error of the layer, For the first Layer connection nodes, To account for manufacturing errors, Due to installation error, This is the interlayer error correlation coefficient. This refers to the allowable error limit for a single connection point. This is the error influence coefficient. , , To correspond to the local column section height, local beam section bending stiffness, and local beam span of the connection node, For elastic modulus, For effective inertial torque, It is the inverse function of the standard normal distribution. This is the minimum reduction factor. For target reliability indicators; The adaptive tolerance error limits of all connection nodes on the same layer are summed to obtain the cumulative adaptive tolerance error limit. The cumulative error is compared with the cumulative adaptive tolerance error limit. When the cumulative error exceeds the cumulative adaptive tolerance error limit, the controllable parameters of the connection node are finely adjusted during the construction of the next layer of prefabricated modules. The controllable parameters include the size, strength grade and preload of the connection component. In actual evaluation, manufacturing error is considered when calculating cumulative error. , Follows a normal distribution. , This represents the mean and variance of the manufacturing errors of all connecting components at the corresponding node. , The mean and variance of the errors generated during on-site installation and construction of the corresponding nodes are taken as the inter-layer error correlation coefficient of 0.3-0.5 and the target reliability index of 3.2-3.7. During the construction phase of prefabricated modular buildings, controllable parameters of the connection nodes can only be fine-tuned during the construction of the next layer of prefabricated modules. The reasons are as follows: First, the position / quantity of the connecting components at the connection nodes cannot be adjusted. When the cumulative error of a certain layer is detected to exceed the standard, the prefabricated components of the next layer have already been produced or even transported to the site. Adjusting the position / quantity of the connecting components at this point means scrapping the already produced modules (as the holes for the connecting components are pre-set on the prefabricated components) or returning them to the factory for modification, which is extremely costly and disrupts the factory's production rhythm, thus losing the time advantage of modular buildings. Second, due to the irreversible cumulative nature of installation errors (improving the precision of the upper layer cannot eliminate the errors already generated in the lower layer), it is inconvenient to propose stricter installation error standards (forcibly tightening construction standards would lead to a sharp decline in construction efficiency, violating the core value of rapid construction in modular buildings). Therefore, the commonly adopted methods include increasing the thickness of the end plates, increasing the strength grade of the bolts, and applying pre-tightening force. Taking the fine-tuning of controllable parameters after the construction of the first floor of a 6-story modular steel structure office building as an example, the construction error of all connection nodes on the first floor was measured by using a total station combined with a laser tracker. The cumulative error of the 24 connection nodes (4 corner nodes + 8 edge nodes + 12 internal nodes) on the first floor was 72.5mm. Based on the building target reliability, the adaptive allowable error limit of each connection node is calculated. Taking the adaptive allowable error limit of the corner node of axis A-1 on the first floor as an example, the minimum acceptable stiffness reduction factor is taken as 0.85, and the adaptive allowable error limit of this connection node is calculated to be 3.2. Similarly, the adaptive allowable error limit of all connection nodes on the first floor is calculated. The cumulative adaptive allowable error limit of the first floor of a certain 6-story steel structure modular office building is 68mm. At this time, the cumulative error of the first floor exceeds the cumulative adaptive allowable error limit of the floor. During the construction of the second floor, some controllable parameters of the connection nodes are finely adjusted. The specific strategy is to increase the preload of the bolts on the corner node group connection nodes of the first floor by 180kN, increase the preload of the bolts on the edge node group connection nodes by 150kN, and increase the preload of the bolts on the internal node group connection nodes by 120kN. The construction of the second-floor prefabricated components of a six-story steel-structure modular office building was carried out according to the plan. The construction error was statistically analyzed in real time, and the cumulative error and cumulative adaptive allowable error limit were calculated. Data comparison was carried out to determine the fine-tuning strategy of controllable parameters. When the deviation was large, higher grade bolts and increased plate thickness could be selected (to compensate for the stiffness loss caused by the error and achieve nonlinear compensation effect).

[0021] Secondly, a connection node design system for prefabricated modular buildings includes: Connection Node Determination Module: Used to generate a 3D building model based on architectural drawings and identify the contact area of ​​prefabricated modules, divide the connection node group according to the building's functional location, and determine the number and location of the connection components of each connection node; Target stiffness determination module: used to determine the first target stiffness of each group of connected nodes based on the building's functional location and structure, and to optimize the first target stiffness using a point group stiffness optimization objective function to obtain the second target stiffness; Node state prediction module: used to set different external states and controllable parameter combinations of connected nodes for finite element analysis, and to construct a connected node state prediction model based on the finite element analysis results; Controllable parameter design module: used to reduce the second target stiffness to obtain the initial stiffness target value, and adjust the controllable parameters of the connection node according to the initial stiffness target value and the connection node state prediction model; Controllable parameter fine-tuning module: used to build prefabricated modular buildings based on the controllable parameters of the connection nodes, to count construction errors in real time and calculate cumulative errors, to calculate adaptive allowable error limits based on the building target reliability, and to fine-tune the controllable parameters of the connection nodes in real time based on the comparison results of cumulative errors and cumulative adaptive allowable error limits.

[0022] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for designing connection nodes in prefabricated modular buildings, characterized in that, Includes the following steps: S1. Generate a three-dimensional building model based on architectural drawings and identify the contact area of ​​prefabricated modules. Divide the connection node group according to the functional location of the building and determine the number and location of the connection components of each connection node. S2. Determine the first target stiffness of each connecting node group based on the building's functional location and structure, and use the point group stiffness optimization objective function to optimize the first target stiffness to obtain the second target stiffness; S3. Set different external states and controllable parameter combinations for the connection nodes and perform finite element analysis. Construct a connection node state prediction model based on the finite element analysis results. S4. Reduce the second target stiffness to obtain the initial stiffness target value, and adjust the controllable parameters of the connection node according to the initial stiffness target value and the connection node state prediction model. S5. Construct prefabricated modular buildings based on the controllable parameters of the connection nodes, statistically analyze construction errors and calculate cumulative errors in real time, calculate adaptive allowable error limits based on the building target reliability, and fine-tune the controllable parameters of the connection nodes in real time based on the comparison results of cumulative errors and cumulative adaptive allowable error limits. The connection node group includes corner node group, edge node group and internal node group; The first target stiffness and the second target stiffness are theoretical stiffnesses; The finite element analysis results include initial stiffness, nodal bending moments, and ultimate bending moments of the connected nodal group; The external conditions include the overall building specifications, the specifications of local prefabricated components, the connection methods, and the contact area area. The connection type is associated with the connection node type; The controllable parameters include the number, location, size, strength grade, and preload of the connecting components; The state of the connection node includes initial stiffness and node bending moment; The construction errors include manufacturing errors and installation errors.

2. The connection node design method for prefabricated modular buildings according to claim 1, characterized in that, The method for determining the number and location of connecting components at each connecting node includes: Architectural drawings are input into BIM software to generate a 3D building model. The software identifies the contact areas of each prefabricated module as connection nodes. The type of connection node is determined according to the functional location of the building, and connection node groups are divided. The connection node groups include corner node groups, edge node groups, and internal node groups. Determine the standard connection form for different connection nodes; the standard connection form is associated with the type of connection node group, including the standard contact area, the standard number of connection components, and the standard arrangement of connection components; Calculate the ratio of the actual contact area of ​​each connection node of the prefabricated modular building to the corresponding standard contact area. Determine the number and location of the corresponding connection components based on the contact area ratio. The number of connection components for each connection node of the prefabricated modular building to be designed is the product of the corresponding contact area ratio and the standard number. The arrangement of the connection components for each connection node of the prefabricated modular building to be designed is consistent with the corresponding standard arrangement.

3. The connection node design method for prefabricated modular buildings according to claim 1, characterized in that, The method for obtaining the second target stiffness includes: The first target stiffness of each group of connecting nodes is determined based on the building's functional location and structure, expressed as follows: ; in for The first target stiffness of the class connection node, This refers to the design value of the floor shear force. For floor height, This is the limit value for the inter-story drift angle. for Number of class-connected nodes For the first The distance from each point to the center of rigidity of the structure. for Adjustment coefficient for class-connected nodes; The first objective stiffness is optimized using a point group stiffness optimization objective function until the stiffness optimization objective function is minimized. The corresponding objective stiffness is then output as the second objective stiffness, expressed as: ; ; in The objective function for optimizing the stiffness of the point group is... , , Assign weights to the target. The stiffness matching index. The total mass of the structure. This is the upper limit of quality. For the basic period of the structure, For periodic limits, For the number of floors, , For stiffness matching degree weight, For the first The coefficient of variation of stiffness of all connected nodes in the layer. For the first Maximum stiffness deviation rate of the layer.

4. The connection node design method for prefabricated modular buildings according to claim 1, characterized in that, The method for constructing a connection node state prediction model includes: Orthogonal experimental design was carried out according to the connection node type, external state and controllable parameters. Different parameter combinations were generated for finite element analysis. The initial stiffness, nodal bending moment and ultimate bending moment of each node were extracted. The minimum value of the ultimate bending moment of the same type of connection node was taken as the ultimate bending moment of the connection node group. A three-parameter power function model is fitted to the initial stiffness, nodal moments, and ultimate bending moments of the connected node group to obtain the nodal moment-initial stiffness mapping relationship, expressed as: ; in for Nodal bending moment of the connecting nodes, for Initial stiffness of the connection node, For the corner of the connection point, For reference, plastic rotation angle, for Connecting nodes to corresponding node types Ultimate bending moment of the group of connecting nodes; The node types, external states, controllable parameters, and initial stiffness from the finite element analysis results are combined into a comprehensive set. The comprehensive set is then randomly divided into a training set and a test set in a 6:4 ratio. The training set is used to train the connection node state prediction model, and the test set is used to evaluate the model performance. The connection node state prediction model includes an input layer, a feature processing layer, an initial stiffness prediction layer, a node bending moment prediction layer, and an output layer. The feature processing layer uses an attention mechanism to fuse node type, external state, and controllable parameters to obtain connection node features. The initial stiffness prediction layer uses a gradient boosting tree algorithm to establish a nonlinear mapping relationship between connection node features and initial stiffness, and predicts the initial stiffness of each connection node. The node bending moment prediction layer embeds a node bending moment-initial stiffness mapping relationship and predicts the corresponding node bending moment of each connection node based on the prediction results of the initial stiffness prediction layer.

5. The connection node design method for prefabricated modular buildings according to claim 1, characterized in that, The method for adjusting the controllable parameters of the connection node includes: The stiffness reduction factor for each connection node is calculated based on the allowable cumulative error of the building. The initial stiffness target value is obtained by reducing the second target stiffness, as expressed by: ; in This is the stiffness reduction factor. This is the error influence coefficient. To allow for cumulative errors in construction, The height of the local column section at the connection node. To determine the bending stiffness of the local beam section at the connection node, For elastic modulus, For effective inertial torque, The second target stiffness corresponds to the connection node. For the local beam span of the connection node; The connection node type, external state, and controllable parameters of the prefabricated modular building to be designed are input into the connection node state prediction model to obtain the initial stiffness prediction value and the node bending moment prediction value of each connection node. The values ​​are compared with the corresponding initial stiffness target value. When the initial stiffness prediction value is less than the corresponding initial stiffness target value or the node bending moment prediction value is greater than the corresponding node bending moment threshold, the controllable parameters of the corresponding connection node are adjusted, and the initial stiffness prediction value and the node bending moment prediction value are updated again by inputting them into the connection node state prediction model. The process continues until the initial stiffness prediction value and the node bending moment prediction value of all nodes meet the requirements.

6. The connection node design method for prefabricated modular buildings according to claim 1, characterized in that, The method for fine-tuning the controllable parameters of the connection node includes: Prefabricated modular buildings are constructed based on controllable parameters of connection nodes. Construction errors are statistically analyzed in real time and cumulative errors are calculated. Adaptive allowable error limits are calculated based on the target reliability of the building. The expression is as follows: ; ; in No. The cumulative error of the layer, For the first Layer connection nodes, To account for manufacturing errors, Due to installation error, This is the interlayer error correlation coefficient. This refers to the allowable error limit for a single connection point. This is the error influence coefficient. , , To correspond to the local column section height, local beam section bending stiffness, and local beam span of the connection node, For elastic modulus, For effective inertial torque, It is the inverse function of the standard normal distribution. This is the minimum reduction factor. For target reliability indicators; The adaptive tolerance error limits of all connection nodes on the same layer are summed to obtain the cumulative adaptive tolerance error limit. The cumulative error is compared with the cumulative adaptive tolerance error limit. When the cumulative error exceeds the cumulative adaptive tolerance error limit, the controllable parameters of the connection node are finely adjusted during the construction of the next layer of prefabricated modules. The controllable parameters include the size of the connection component, the strength grade, and the preload.

7. A connection node design system for prefabricated modular buildings, used to perform the method according to any one of claims 1-6, characterized in that, include: Connection Node Determination Module: Used to generate a 3D building model based on architectural drawings and identify the contact area of ​​prefabricated modules, divide the connection node group according to the building's functional location, and determine the number and location of the connection components of each connection node; Target stiffness determination module: used to determine the first target stiffness of each group of connected nodes based on the building's functional location and structure, and to optimize the first target stiffness using a point group stiffness optimization objective function to obtain the second target stiffness; Node state prediction module: used to set different external states and controllable parameter combinations of connected nodes for finite element analysis, and to construct a connected node state prediction model based on the finite element analysis results; Controllable parameter design module: used to reduce the second target stiffness to obtain the initial stiffness target value, and adjust the controllable parameters of the connection node according to the initial stiffness target value and the connection node state prediction model; Controllable parameter fine-tuning module: used to build prefabricated modular buildings based on the controllable parameters of the connection nodes, to count construction errors in real time and calculate cumulative errors, to calculate adaptive allowable error limits based on the building target reliability, and to fine-tune the controllable parameters of the connection nodes in real time based on the comparison results of cumulative errors and cumulative adaptive allowable error limits.

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