A bim-based composite modeling and domain gathering method for fabricated heterogeneous concrete structures

Abstract

This invention discloses a BIM-based composite modeling and domain-based aggregation method for prefabricated heterogeneous concrete structures, belonging to the field of prefabricated concrete building construction and BIM technology. This invention aims to solve the problems of the inability to automatically separate the quantities of precast walls and cast-in-place components, and the difficulty in accurately controlling the anchorage length of reinforcing bars in existing BIM modeling. The method includes: establishing custom precast wall components and configuring reinforcing bar layout rules; constructing a grouted cast-in-place layer model with a predetermined geometric thickness and no reinforcing bars between the precast wall and the cast-in-place component; assembling the precast wall and the grouted cast-in-place layer to form a structural composite model; using the grouted cast-in-place layer as the separation boundary, automatically classifying, statistically analyzing, and outputting the quantities of the precast and cast-in-place parts of the wall and the cast-in-place hidden columns on both sides. This invention also sets calculation rules such as differentiated vertical reinforcing bar connections, segmented horizontal reinforcing bar anchorage, and bottom-densified spacing, and ensures data accuracy through geometric deduction and dual verification of reinforcing bar length.

Description

Technical Field

[0001] This invention relates to the field of prefabricated concrete building construction and Building Information Modeling (BIM) technology application, specifically to a BIM-based method for composite modeling and domain aggregation of prefabricated heterogeneous concrete structures. Background Technology

[0002] Currently, prefabricated construction is developing rapidly, but the corresponding BIM quantity surveying methods still have significant shortcomings. While existing BIM software (such as the Glodon prefabricated module) can output prefabricated construction quantity data, reinforcement information still needs to be manually entered and cannot generate a visualized 3D reinforcement model, resulting in a "quantity without model" defect in reinforcement quantity surveying. Furthermore, in the case of prefabricated walls and cast-in-place columns, due to the complex geometric interfaces and interlocking reinforcement, traditional modeling methods struggle to automatically distinguish the quantities of prefabricated and cast-in-place components, easily leading to omissions or double calculations. Therefore, there is an urgent need for a standardized modeling method that, without the need for additional plugin development, utilizes the basic functions of existing BIM platforms to automatically separate the quantities of prefabricated and cast-in-place components and visualize the 3D reinforcement. Summary of the Invention

[0003] This invention provides a BIM-based composite modeling and domain aggregation method for prefabricated heterogeneous concrete structures, aiming to solve the technical problems existing in the background art.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] In practical engineering, precast concrete walls and cast-in-place concrete components coexist in the same structure. While existing BIM modeling processes can distinguish between the two using their existing functions, the built-in precast component parametric module cannot perform reinforcement calculations; it can only provide the quantity of precast component blocks. Therefore, the integrity and accuracy of BIM model and data transmission cannot be guaranteed. This invention proposes a composite modeling and domain-based aggregation method. This method first establishes a custom component model representing the precast concrete wall and configures reinforcement rules. Then, a cast-in-place grouting layer model is forcibly introduced between this custom component model and the cast-in-place component model. The portion of this grouting layer above 50mm is considered a precast component. After the two are assembled, when performing summary calculations based on this structural combination model, the software system can automatically determine that the 50mm grouting layer is a cast-in-place component, and the portion of the cast-in-place component above 50mm is a precast component, thus outputting their respective quantities. The working process of this solution is as follows: users first create custom precast wall components (not using the precast wall templates provided by the software), and then draw a 20mm cast-in-place grouting layer (without reinforcement) at the corresponding joint positions; during calculation, the system automatically aggregates the components based on their type and spatial relationship. Its advantages are: it embeds domain logic from the modeling stage, eliminating the need for manual splitting later, and can quickly and automatically calculate the amount of reinforcement built into the precast portion, breaking through the technical limitation of "having a mold but no quantity" in the prefabricated construction field, and significantly improving the automation and accuracy of quantity statistics.

[0006] Based on the above technical solutions, the technical solution of this application further specifies that: the cast-in-place grouting layer model is constructed as an independent component model with a predetermined geometric thickness and no reinforcement information, and the predetermined geometric thickness is 20 mm. The reason for setting 20 mm is that in actual prefabricated structures, there is usually a grouting layer or post-cast strip between the bottom of the precast wall and the floor, between upper and lower precast walls, and at the lateral joints between the precast wall and the cast-in-place column, with an actual thickness of approximately 20 mm. Assigning this thickness to the cast-in-place grouting layer not only conforms to the actual structure but also occupies a non-negligible geometric space in the model. This cast-in-place grouting layer does not contain any reinforcement information, so it does not contribute to the reinforcement quantity in the structural stress calculation, but its concrete volume can be separately included in the joint cast-in-place portion during quantity surveying. Its working principle is: because this layer has no reinforcement and its thickness is fixed, the calculation engine will not include it in any reinforcement length when calculating reinforcement; when calculating concrete, it exists as an independent component, thus completely separating the geometric volumes of the precast wall and the cast-in-place column. By setting up independent components with "thickness but no steel reinforcement", the geometric boundaries of precast and cast-in-place parts in the model are clear and their properties are independent, providing a reliable physical basis for subsequent automatic domain division and aggregation.

[0007] In the vertical reinforcement connection of precast concrete walls, there are two typical working conditions: some vertical distributed reinforcements need to be connected to the reserved reinforcements in the lower structure to transfer tensile force, while others do not need to be connected due to structural reasons and only need to be cut off at the bottom of the wall. The existing functions of BIM software currently do not have parametric modeling capabilities for such node structures. To solve the technical problem of "differentiated modeling of vertical distributed reinforcement connection methods," the following settings were made when configuring the reinforcement layout rules using a custom method: For vertical distributed reinforcements that need to be connected, their length extending into the lower structure is set to a standard anchorage length according to national standard drawings and design requirements; for vertical distributed reinforcements that do not need to be connected, they are cut off within a preset range at the bottom of the wall at a length equal to 8 times the diameter of the reinforcement. In terms of working principle, when the user defines the precast wall component, constraints are applied to the bottom extension length of the two types of reinforcements by editing the "start offset" and "end offset" attributes of the reinforcement. These constraint values ​​are directly taken from the structural detailed design drawings and national standard drawings, ensuring that each vertical reinforcement in the model accurately reflects the actual structure. The beneficial effects are: it realizes differentiated modeling of connected and unconnected reinforcing bars in the same wall, which not only ensures the anchorage reliability of the stressed reinforcing bars, but also avoids unnecessary overestimation of the length of connected reinforcing bars, so that the reinforcement quantity statistics are closer to the actual cutting length and truly reflect the design requirements of the drawings and the actual on-site structure.

[0008] Horizontal reinforcing bars in precast walls typically need to extend into the cast-in-place edge members (hidden columns or end columns) on both sides to achieve reliable anchorage. However, if the extension length of the reinforcing bars is fixed as an absolute value when the wall length varies, it cannot adapt to different component sizes; manual adjustment is extremely cumbersome. To automatically adapt to any wall length and ensure minimum anchorage length requirements, the anchorage length of the horizontal reinforcing bars is set to: the length extending into the adjacent cast-in-place edge member is not less than 0.8 times the standard anchorage length. This setting is implemented by entering the calculation expression "0.8 * standard anchorage length" in the "hook" or "extension length" parameter interface for the horizontal reinforcing bars of the custom wall component (the standard anchorage length is automatically obtained by the software based on concrete strength, reinforcing bar grade, and diameter). During model calculation, the system reads the wall length parameters, automatically calculates the net wall length, and then adds 0.8 times the anchorage length at each end to obtain the total length of each horizontal bar. The working principle of this scheme is equivalent to decoupling the anchorage length from the component geometry and associating it only with material parameters. Regardless of the wall length, the length of the horizontally distributed reinforcement bars extending into the cast-in-place components on both sides always meets the minimum anchorage requirement, and there is no need to manually modify each bar individually, which greatly improves the modeling efficiency and the calculation accuracy of the reinforcement length.

[0009] According to the construction and quality acceptance specifications for prefabricated concrete structures, within a certain height range at the bottom of precast walls, due to the presence of sleeve grouting or bedding operations and the complex stress in this area, the horizontally distributed reinforcing bars need to be densely arranged. Existing software, using the default equal-spacing arrangement, cannot meet the density requirements. To automatically achieve a variable-spacing arrangement with denser bars at the bottom and normal spacing at the top in the model, segmented settings were implemented when configuring the reinforcing bar layout rules: within the preset height range at the bottom of the custom precast component model, the spacing of the horizontally distributed reinforcing bars is set to 100 mm (densification value); outside this range, the spacing in the remaining wall areas is restored to 200 mm (design spacing). This is achieved by setting the horizontal reinforcing bar layout rules to "spacing-interval" mode in the reinforcing bar layout editing interface, defining the spacing as 100 mm within the "from the bottom of the wall to the preset height" interval and 200 mm within the "remaining height" interval. This way, when the wall height changes, the number of reinforcing bars in the denser and non-denserified areas is automatically recalculated. The beneficial effects are: it accurately simulates the densified structure in actual construction, ensuring that the horizontal reinforcement arrangement in the model fully complies with the specifications, avoiding the inefficient operation of manually adding or modifying densified reinforcement later, and ensuring the compliance of reinforcement quantity statistics.

[0010] The aforementioned technical solution mentions a "preset bottom height range," but its specific value is undefined and may vary depending on the project. To establish a universal and conventionally designed value, this preset bottom height range is defined as a 300mm area from the bottom of the wall upwards. This value is determined based on the fact that the bottom reinforcement zone height of conventional precast wall panels is typically 300mm, within which horizontal reinforcement needs to be densified to a 100mm spacing; above 300mm, the spacing can be reduced to 200mm. In actual modeling, users define and draw within their respective ranges. Beneficial effects: This provides a clear, universal, and engineering-standard reinforcement zone height value, making the method more operable. Users no longer need to manually determine the reinforcement zone range, reducing subjective arbitrariness in modeling.

[0011] After the model is built and the calculations are summarized, the key to cost control lies in quickly extracting the required quantities of precast and cast-in-place components from the massive model data. To address the issue of unclear filtering conditions for quantity classification extraction, this application specifies the categories and extraction methods for the output quantities. Specifically, the output quantities of precast and cast-in-place components must include at least the concrete volume, the specifications / models / lengths / weights of the structural reinforcement, and the formwork area. Precast quantities are extracted by filtering the component category as "precast wall component," while cast-in-place quantities are extracted by filtering the component name as the corresponding cast-in-place component name (e.g., "cast-in-place concrete column," "cast-in-place connecting beam," etc.). The process is as follows: In the BIM software's schedule function, two independent schedules are created. One is set to filter "Family and Type" to include "precast wall," and the other is set to filter "Family and Type" to include keywords such as "cast-in-place column / cast-in-place wall." The software automatically filters out components that meet the conditions from the model and summarizes their volume, reinforcement, formwork, and other parameters. The beneficial effects are: it provides business quantity verification personnel with a standardized engineering quantity classification and extraction scheme, which can generate independent engineering quantity lists for prefabricated and cast-in-place parts with one click without manually selecting components, greatly improving the efficiency and accuracy of settlement and cost accounting.

[0012] The accuracy of the engineering quantities calculated by the model requires a repeatable and quantifiable verification method. To address the lack of a model self-checking method, a data verification step is introduced, including two specific methods: geometric deduction verification and rebar length verification. The working principle of geometric deduction verification is as follows: Since the cast-in-place grouting layer model occupies the joint space, the sum of the precast wall volume and the cast-in-place component volume should theoretically equal the overall design volume of the structure (i.e., the integrated volume without considering joints). Users extract these three volume values ​​separately, sum them, and compare them with the total design volume. If it accurately reflects the design requirements, it proves that there is no geometric overlap or omission in the model (i.e., no double calculation or undercalculation). The principle of rebar length verification is: randomly select any horizontally distributed rebar in the model and check its total length attribute. This length should equal "net wall length + 2 × (0.8 times the standard anchorage length)". Users can verify this by measuring the net wall length and calculating manually. Two simple and effective methods for verifying model accuracy are provided, enabling modelers and reviewers to quickly locate modeling errors (such as deviations in the geometric properties of the cast-in-place grouting layer, incorrect setting of the rebar anchorage length, etc.), thereby ensuring the credibility of the final engineering quantity data.

[0013] The model data generated by the method of this invention should not be limited to quantity calculations, but should also be transferable to downstream processes to realize greater value. To address the problem of "BIM model being disconnected from production and construction processes," the data reuse steps are defined: the output rebar detail list is directly sent to the precast component manufacturing plant to guide precast component production; simultaneously, the 3D rebar model in the structural assembly model is used for technical briefings and alignment of reserved rebars at the construction site. This is achieved by exporting a "reserved / connected rebar detail list" (containing fields such as rebar specifications, cutting length, bending shape, and quantity) from the BIM software and sending it to the factory in Excel or PDF format; simultaneously, the model file containing the 3D rebar is published to a lightweight display platform for on-site construction personnel to view on mobile devices. The working principle is: the factory processes and pre-embeds rebars based on the length data in the detail list, while on-site personnel use the 3D model to visually compare the positional relationship between the reserved rebars and the cast-in-place column rebars during precast wall hoisting. It enables lossless data transfer from design model to prefabrication and on-site construction, avoiding the errors caused by the traditional method of "production based on two-dimensional drawings and construction based on experience", and reducing on-site steel bar alignment conflicts and rework.

[0014] In actual modeling, the precise elevation of the cast-in-place grouting layer and whether the reinforcing bars pass through this layer directly affect the realism of the model's appearance and the accuracy of its stress representation. To address the issue of "ambiguous definition of the cast-in-place grouting layer's location," further restrictions are imposed: the elevation of the cast-in-place grouting layer model is set to be 20 mm above the floor level, and the reinforcing bars in the custom component model are configured to geometrically pass continuously through this cast-in-place grouting layer model. The 20 mm offset corresponds to the actual thickness of the grouting layer at the bottom of the precast wall, ensuring the infill layer is precisely located between the bottom surface of the precast wall and the top surface of the floor slab. The continuous passage of the reinforcing bars through this layer is achieved by not treating the cast-in-place grouting layer as an obstacle to the reinforcing bar arrangement in the custom component—that is, when drawing the reinforcing bars, their path spans the elevation range of the infill layer without being truncated by the layer's entity. Thus, in the 3D view, users can clearly see the vertical reinforcing bars extending upwards from the lower structure, passing through the 20 mm thick infill layer, and continuing into the precast wall. Beneficial effects: It ensures the geometric independence of the cast-in-place grouting layer as the boundary for separating engineering quantities, and avoids visual interruption or calculation errors of the reinforcement due to the insertion of this layer. It truly reflects the mechanical behavior of continuous force transmission of reinforcement in the actual structure, so that the model can meet the dual requirements of quantity calculation accuracy and visualization realism.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] 1. A pioneering domain-based aggregation mechanism for "cast-in-place grouting layers and precast components with 3D rebar display" was established, enabling automatic separation of precast and cast-in-place project quantities.

[0017] Existing BIM quantity calculation software typically treats precast walls and cast-in-place columns as independent components when handling mixed structures. While there are separate precast module functions, they can only provide information on the number and quantity of precast components, and cannot perform detailed decomposition. This invention is the first to propose a custom decomposition drawing of precast wall components with annotations. During the summary calculation, the precast and cast-in-place parts are automatically distinguished without any manual intervention. This mechanism fundamentally solves the industry pain points of unclear quantity attribution and inability to extract detailed material usage in prefabricated-cast-in-place concrete structures, enabling domain division to be completed during modeling.

[0018] 2. Achieve "quantitative and three-dimensional visualization" of reinforcing steel, eliminating the "black box" state of traditional quantity calculation.

[0019] Traditional prefabricated quantity take-off (such as Glodon software) can output the quantity of prefabricated component blocks, but the reinforcement information is manually entered and cannot generate a 3D reinforcement model. Users cannot intuitively verify whether the reinforcement layout meets the structural requirements, resulting in a "quantity without model" defect. This invention, through custom parametric components, directly configures the rules for reinforcement anchorage length, lap length, and densification intervals specified in national standard drawings into the BIM model. This makes each horizontal and vertical reinforcement bar present as a 3D solid form, and its length, bends, and extension range can be selected and viewed. Users can rotate and section the model for visual verification, completely eliminating the blind spots of "invisible and unsearchable" reinforcement data in traditional quantity take-off.

[0020] 3. Establish intelligent rebar layout rules based on "parametric anchoring + segmented spacing" to significantly improve the accuracy of rebar quantity measurements.

[0021] To address the diverse structural requirements for steel reinforcement connections in prefabricated structures, this invention embeds the following differentiated settings into custom components:

[0022] Vertical reinforcement: Distinguish between "connecting bars" and "non-connecting bars", and set them to extend into the lower layer by one standard anchorage length (Lae) or cut and bend them at the bottom of the wall at 8 times the diameter of the reinforcement bar;

[0023] Horizontal reinforcement bars: The ends automatically extend into the cast-in-place edge members at 0.8 times the standard anchorage length, adapting to any wall length variation;

[0024] Bottom reinforcement zone: The spacing of horizontal ribs is automatically reduced from the usual 200mm to 100mm (reinforcement zone height 300mm).

[0025] Once the above rules are set, the model will automatically adapt to different wall heights and lengths without the need for manual adjustments to each wall. The accuracy of steel reinforcement quantity statistics can reach the material cutting level, and it can be directly used for factory production.

[0026] 4. Construct a dual verification closed loop of "geometric deduction + rebar length" to ensure the reliability of model data.

[0027] Existing BIM quantity calculation processes generally lack standardized model self-checking methods, and errors are often only discovered during the quantity verification stage, resulting in high rework costs. This invention incorporates two independent verification methods:

[0028] Geometric deduction verification: By utilizing the existence of the grouting cast-in-place layer, it verifies whether the "precast volume + cast-in-place volume + infill layer volume" equals the overall structural design volume, and quickly identifies overlaps, omissions and deviations;

[0029] Reinforcement length verification: Randomly select horizontally distributed reinforcement bars and check whether their calculated length is equal to "net wall length + 2 × 0.8 times standard anchorage length" to ensure that the anchorage rules are effective.

[0030] These two verification methods are highly operable and have clearly defined judgment thresholds, enabling modelers to conduct immediate self-checks after summarizing, significantly reducing disputes in the subsequent verification stage.

[0031] 5. Establish a seamless data link between "model → production → construction" to enable the reuse of the same model across multiple stages.

[0032] This invention not only serves quantity calculation, but also extends to the precast component production and on-site construction processes:

[0033] On the production side: The exported "rebar detail list" contains the specifications, cutting length and quantity of each rebar, which can be directly sent to the precast component factory for rebar processing and pre-embedded positioning, replacing the traditional manual reading of two-dimensional drawings;

[0034] On the construction side: The 3D rebar model is delivered to the site in the form of a scheme export. Managers can intuitively view the spatial relationship between the reserved rebar and the cast-in-place column rebar on a tablet computer. This is used for alignment and handover before hoisting, reducing rebar collisions and rework.

[0035] This "one model, multiple uses" approach upgrades the BIM model from a simple quantity calculation tool to a digital thread that runs through the entire design, production, and construction process.

[0036] 6. It relies entirely on the existing BIM platform's basic functions, requiring no additional development or purchase of plugins.

[0037] Unlike BIM detailing solutions that require secondary development or dedicated plugins, this invention operates entirely based on the built-in functions of BIM software (custom families, rebar layout editing, schedule filtering, virtual component drawing, etc.). Any team with basic BIM modeling capabilities can implement it directly without additional software investment or programming development, significantly reducing the barrier to entry and cost of technology promotion, and demonstrating good industry applicability. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0039] Figure 1 This is a schematic diagram of the arrangement and anchorage of vertical and horizontal reinforcing bars inside the precast wall component in the method of the present invention. It shows the anchorage length of the connected vertical reinforcing bars extending into the lower structure, the cut-off length of the unconnected reinforcing bars at the bottom of the wall (8 times the diameter of the reinforcing bar), and the 0.8 times standard anchorage length of the end of the horizontal reinforcing bars extending into the cast-in-place edge component.

[0040] Figure 2 This is a three-dimensional schematic diagram of the precast wall, cast-in-place grout layer, and precast wall components assembled by the method of the present invention. It focuses on showing the spatial position of the 20mm thick cast-in-place grout layer at the bottom of the precast wall and at the side joints.

[0041] Figure 3 This is a three-dimensional diagram showing the anchorage of horizontally distributed reinforcing bars in the joint area between precast walls and cast-in-place columns in the method of this invention. It is used to verify whether the calculated length of the reinforcing bars is equal to the net length of the wall plus 0.8 times the standard anchorage length at both ends.

[0042] Figure 4 This is a schematic diagram of the three-dimensional model of the precast wall reinforcement generated by the method of the present invention, used to guide the alignment and installation of reinforcement and technical briefings on the construction site. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0044] The following is in conjunction with the appendix Figure 1-4 The invention will be further described in detail with specific engineering embodiments. This embodiment takes a precast concrete shear wall and its two cast-in-place hidden columns on both sides in a standard floor of a prefabricated residential project as an example, and uses BIM software for illustration. However, the scope of protection of the invention is not limited to this software or this specific example.

[0045] I. Preliminary Preparations and Component Customization

[0046] Step 1: Create custom precast wall components

[0047] The operator first creates a new "Metric Structural Wall" family file in the BIM software, without using the software's built-in "Precast Wall" template. In the family editor, the wall's thickness, length, height, and other geometric parameters are set to variable parameters to match the actual dimensions in the detailed design drawings. Simultaneously, the family category is set to "Structural Wall," and an instance parameter "Component Type" is added to the "Family Parameters," with a default value set to "Precast Concrete Wall," for subsequent quantity filtering.

[0048] Step 2: Configure the connection rules for vertical distribution reinforcement.

[0049] Enter the reinforcement editing interface. According to the detailed drawings of the precast components for this project and the national standard drawing set 16G101-1, the bottom 500mm area of ​​this wall is a reinforced zone. For vertically distributed reinforcement, the operator sets two working conditions as follows:

[0050] For the connected vertical reinforcing bars: In the reinforcing bar properties, set the bottom extension length to "extend into the lower structure by one standard anchorage length (Lae)". The specific value of Lae is automatically calculated by the software based on the concrete strength grade C40 and the reinforcing bar diameter of 14mm, and is approximately 600mm.

[0051] Disconnected vertical reinforcing bars: Within the preset range at the bottom of the wall (500mm in this embodiment), the starting offset of this type of reinforcing bar is set to "8 times the diameter of the reinforcing bar above the bottom elevation of the wall (i.e., 8×14=112mm)".

[0052] With the above settings, each vertical steel bar in the model can display a different bottom structure depending on whether it plays a connecting role.

[0053] Step 3: Configure the anchorage and spacing of the horizontally distributed reinforcing bars.

[0054] Horizontal reinforcement anchorage length: In the properties panel of the horizontally distributed reinforcement, find the "Endpoint Extension Length" option and enter the expression "0.8 * Lae". Lae is also automatically obtained by the software based on C40 concrete and HRB400 grade reinforcement, and after multiplying by 0.8, it is approximately 480mm. In this way, no matter how the wall length changes, the length of the horizontal reinforcement extending into the cast-in-place hidden columns on both sides will always be no less than 480mm.

[0055] Bottom reinforced zone: Set the horizontal reinforcement arrangement to "spacing interval". Define the first interval as "300mm from the bottom of the wall upwards", with a spacing of 100mm; the second interval is "from 300mm to the top of the wall", with a spacing of 200mm. The software automatically calculates that the reinforced zone requires 3 horizontal reinforcements, and the non-reinforced zone requires (wall height - 300) / 200 reinforcements.

[0056] II. Combined Modeling and Insertion of Grouting Cast-in-Place Layer

[0057] Step 4: Draw the precast wall and insert the grouting layer for cast-in-place.

[0058] In the project floor plan, following the positioning in the detailed drawings, first draw the aforementioned custom precast concrete wall. Set its top elevation to the floor top elevation minus 20mm (to allow for the upper joint), and its bottom elevation to the floor bottom elevation. Then, select the "Wall" tool and create an independent wall component with a thickness of 20mm, using "Construction Mortar" material, and without any reinforcing steel. Set its bottom constraint to the "Floor Bottom Elevation" and its top offset to "20mm," placing it precisely between the bottom of the precast wall and the top surface of the floor slab. Similarly, at the horizontal joint between the precast wall and the two cast-in-place columns (i.e., the gap between the wall end and the column edge), draw a 20mm thick vertical grouting layer with the same width as the wall thickness and the same height as the precast wall. This filling layer geometrically completely separates the precast wall from the cast-in-place columns.

[0059] Step 5: Draw the cast-in-place edge components

[0060] On both sides of the precast wall, draw cast-in-place concrete hidden columns (or corner columns) according to the design drawings. Their geometric dimensions and reinforcement are input according to the conventional cast-in-place structure method. When modeling, ensure that the side of the cast-in-place column fits tightly with the side of the grouted cast-in-place layer, without overlap or gaps.

[0061] Step 6: Install reinforcing bars that continuously pass through the grouting layer.

[0062] In a custom precast wall family, examine the path range of the vertically distributed reinforcing bars. By adjusting the "Reference Elevation" and "Top Extension" of the reinforcing bars, ensure that their starting point is below the floor level (entering the lower level) and their ending point is above the top of the cast-in-place grout layer, thus making it appear in the 3D view that the reinforcing bars continuously pass through a 20mm thick infill layer. This setting does not require modifying the properties of the infill layer itself; it can be achieved simply by adjusting the geometry of the reinforcing bars.

[0063] III. Model Summary Calculation and Engineering Quantity Domain Allocation

[0064] Step 7: Perform calculations and output reports.

[0065] After completing the entire model construction, run the "Summary Calculation" function of the BIM software. Once the calculation is complete, create two detail tables:

[0066] Precast Component Schedule: The filter is set to "Families and Types" and includes "Precast Concrete Wall" (i.e., a custom family name). The schedule includes fields such as "Volume," "Total Reinforcement Weight," and "Formwork Area." The system automatically summarizes the concrete volume, total reinforcement weight, and formwork area of ​​the wall.

[0067] Cast-in-place section details: The filter is set to "Families and Types" including "Cast-in-place Hidden Columns". Similarly, add Volume, Reinforcement, and Formwork fields to obtain the total concrete volume and total reinforcement weight of the hidden columns on both sides.

[0068] Connect the reinforcement bill of materials: By filtering the reinforcement bill of materials and the reinforcement calculation sheet, the resulting precast component material list can be directly used for material cutting at the precast plant.

[0069] Step 8: Data Validation

[0070] Geometric deduction verification: The volume of the precast wall, the volume of the hidden columns on both sides, and the volume of the cast-in-place layer with grout are summed to obtain the integrated volume of the combined node in the overall structural design drawings, which is completely consistent with the manual calculation.

[0071] Reinforcement length verification: Manually measure the net length of the wall, with 0.8*d anchored at both ends, and the sum is the net length of the wall + 2*0.8*d. The manual measurement and calculation values ​​are completely consistent with the software calculation values.

[0072] IV. Data Reuse and Construction Guidance

[0073] Step 9: Export data for production and field use

[0074] Export the "Rebar Connection Details" as an Excel file and send it to the precast component manufacturer. The manufacturer will cut the rebars according to the lengths specified in the table and embed them into the precast wall formwork.

[0075] The reinforcement technical solution, exported from BIM software based on a complete 3D reinforcement model, was presented via tablet computer at the on-site technical briefing. Construction personnel could rotate and section the model to visually see the location and elevation of the reserved reinforcement bars, thus accurately aligning the cast-in-place reinforcement bars when hoisting precast walls and avoiding rework due to reinforcement bar conflicts requiring secondary drilling.

[0076] Thus, this embodiment completes the entire process from modeling, quantity surveying, verification to production and construction guidance. Through the specific operations described above, the effectiveness and reliability of the method of this invention in automatically separating precast and cast-in-place quantities, accurately calculating rebar length, and enabling model data reuse have been verified.

[0077] 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, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A BIM-based composite modeling and domain-based aggregation method for prefabricated heterogeneous concrete structures, used to automatically separate and calculate the quantities of precast concrete components and cast-in-place concrete components within the same BIM model, characterized in that... Includes the following steps: Establish at least one custom component model to characterize the precast concrete wall, and configure the reinforcement arrangement rules in the model; Below the custom prefabricated components, a grouting cast-in-place layer model is established to define the geometric boundaries and the allocation of engineering quantities; The custom component model, the grouting layer model, and the cast-in-place concrete component model are combined and assembled to form a structural assembly model; Based on the structural combination model, a summary calculation is performed, and the precast concrete layer model is used as the separation boundary to automatically classify, count, and output the quantities of the precast and cast-in-place parts.

2. The method according to claim 1, characterized in that, The grouting cast-in-place layer model is constructed as an independent component model with a predetermined geometric thickness and no reinforcement information, the predetermined geometric thickness being 20 mm.

3. The method according to claim 1, characterized in that, The rules for configuring the arrangement of steel bars include: setting the connection method of vertical distributed steel bars, wherein the length of the connected vertical distributed steel bars extending into the lower structure is one standard anchorage length, and the unconnected vertical distributed steel bars are cut off within a preset range at the bottom of the wall at a length of 8 times the steel bar diameter.

4. The method according to claim 1, characterized in that, The rules for configuring the reinforcement arrangement also include: setting the anchorage length of the horizontally distributed reinforcement so that the length of the horizontally distributed reinforcement extending into the adjacent cast-in-place edge member is not less than 0.8 times the standard anchorage length.

5. The method according to claim 1, characterized in that, The configuration of the reinforcement arrangement rules also includes: setting a denser horizontal distribution reinforcement spacing within the bottom preset height range of the custom component model, wherein the dense spacing is 100 mm; and arranging the horizontal distribution reinforcement at a design spacing of 200 mm in the remaining wall area outside the bottom preset height range.

6. The method according to claim 5, characterized in that, The encrypted area and the unencrypted area are separated by a preset bottom height of 300mm.

7. The method according to claim 1, characterized in that, The quantities of the precast and cast-in-place components include at least: concrete volume, specifications, models, lengths and weights of structural steel reinforcement, and formwork area; wherein, the quantities of the precast components are extracted by filtering the component category as "precast wall components", and the quantities of the cast-in-place components are extracted by filtering the component name as the corresponding cast-in-place component name.

8. The method according to claim 1, characterized in that, It also includes data verification steps: verifying the calculation results of the structural combination model through geometric deduction verification and rebar length verification; the geometric deduction verification is to verify whether the sum of the volume of the custom precast component model, the volume of the parameterized cast-in-place concrete hidden column component model and the volume of the parameterized grouting cast-in-place layer model is completely equal to the overall design volume of the structure; the rebar length verification is to verify whether the calculated length of the horizontally distributed rebar is equal to the net length of the wall plus twice the standard anchorage length of 0.8 times.

9. The method according to claim 1, characterized in that, It also includes a data reuse step: the output list of connecting steel bars is sent directly to the precast component manufacturing plant to guide component production; and the three-dimensional steel bar model in the structural combination model is used for technical briefings and alignment and installation of reserved steel bars on the construction site.

10. The method according to claim 1, characterized in that, The elevation of the grouting cast-in-place layer model is set to be 20 mm above the floor level, and the reinforcing bars in the custom component model are configured to geometrically pass through the grouting cast-in-place layer model to ensure the visual representation of the structural stress continuity in the model.

Images