An ultra-high performance concrete core column slab and an integrated design method thereof

Abstract

The application discloses an ultra-high performance concrete core column plate and an integrated design method thereof. According to the bending moment envelope, the plate span is divided into a pure bending section and a shear span section along the plate span direction, and the UHPC core column spacing, the plate thickness and the tensile reinforcement ratio are adjusted in different sections. In the bending moment peak value area, the core column spacing is reduced, the bottom plate thickness and the reinforcement ratio are appropriately increased, in the smaller bending moment area, the core column spacing is increased, and the reinforcement ratio is reduced, so as to control the dead weight and the cost. The relative density of the core column continuously or sectionally changes in the full span range. Based on the approximate linear relationship among the bearing capacity, the UHPC tensile strength, the tensile reinforcement ratio and the plate thickness, a bearing capacity expression is established, the material performance and the structural parameters of each section are reversely calculated by taking the bending moment and the deflection limit value as constraints, the cross-direction gradient configuration of the UHPC and the steel reinforcement is realized, and the economy and the structural performance are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of building structural engineering, specifically to an ultra-high performance concrete core column slab and its integrated design method, applicable to large-span floor slabs, bridge decks and other UHPC slab structures that require both high load-bearing capacity and lightweight design. Background Technology

[0002] Ultra-high performance concrete (UHPC) is characterized by high strength, high toughness, and high durability, and has been widely used in bridge decks, prefabricated floor slabs, and sandwich components in recent years. In existing UHPC sandwich panels or hollow slabs, UHPC ribs or short columns are typically arranged in the thickness direction to form a sandwich structure, thereby improving stiffness and load-bearing capacity while reducing self-weight. For ease of design and construction, the core columns (or ribs) often employ uniform spacing and constant cross-sectional parameters across the span. The tensile reinforcement ratio and panel thickness also remain largely constant throughout the span, adapting to different internal force requirements only through overall thickness or local thickening.

[0003] However, for actual bending members, the bending moment is unevenly distributed along the span, with the peak bending moment region near the mid-span and the shear span sections near the supports at both ends. In existing technologies, when the slab thickness, core column spacing, and reinforcement ratio are uniformly determined based on the maximum bending moment at mid-span, it often leads to material waste in the low-bending-moment region; if designed based on average internal forces, it is difficult to balance stiffness and crack control in the high-bending-moment region. In addition, some literature has attempted to improve material utilization through variable cross-section plates or locally denser reinforcement, but these mostly involve local optimization of slab thickness or reinforcement, while the density of core columns or ribs remains constant along the span, and a systematic integrated design of "span-specific variable density + performance gradient" has not yet been formed.

[0004] In terms of design methodology, traditional UHPC slab design typically follows the calculation approach used for ordinary reinforced concrete slabs. It involves several iterations and parameter adjustments using formulas for the bearing capacity of component sections and empirical reinforcement principles, combined with finite element analysis. This approach fails to explicitly demonstrate the coupled influence of UHPC tensile properties, slab thickness, reinforcement ratio, and core column density on bearing capacity and deflection. Even when studies indicate an approximately linear relationship between the bearing capacity of UHPC slabs and material tensile strength, tensile reinforcement ratio, and slab thickness, these findings are often used to provide unified optimization schemes, rather than further developing inverse calculation methods for span parameters based on moment distribution. This lack of an integrated design process that can directly guide the variable density arrangement and reinforcement distribution of core columns is also problematic.

[0005] In addition, existing variable cross-section or irregularly reinforced slabs often neglect structural and construction constraints in their application, such as the minimum thickness of the panel, the coordination requirements of the rib width difference, and the minimum control section length of the variable cross-section. This results in theoretically feasible design schemes, but difficulties in construction organization, formwork layout, and quality control.

[0006] In summary, existing technologies have at least the following shortcomings: 1) The arrangement of UHPC core columns or ribs is mostly a constant density across the span, making it difficult to accurately configure materials according to the bending moment distribution; 2) Existing optimizations are mostly focused on the thickness direction, lacking an overall approach of dual gradient of span density and performance; 3) There is a lack of a systematic design method that uses the approximately linear relationship of bearing capacity to back-calculate span parameters, and the design process relies on trial calculations and finite element iterations, which is inefficient and makes it difficult to form repeatable design rules; 4) Insufficient consideration is given to structural and construction feasibility constraints such as minimum plate thickness, rib width difference, and minimum control section length.

[0007] To address the aforementioned problems, this invention proposes a core-column slab structure that coordinates the control of UHPC core column density, slab thickness, and tensile reinforcement ratio along the span based on the bending moment distribution. Furthermore, it establishes parameter back-calculation rules based on an approximately linear relationship of bearing capacity, organically combining material properties, cross-sectional structure, and bending moment envelope to achieve refined allocation of UHPC and steel reinforcement resources along the span, while also considering construction feasibility, thereby improving the novelty and overall economy of the structure. Summary of the Invention

[0008] This invention aims to solve the following problems existing in UHPC core boards:

[0009] 1. Rough material configuration in the span direction: Traditional UHPC core column slabs mostly adopt a design method with constant core column spacing, slab thickness and reinforcement ratio along the span direction. The safety of the entire span can only be controlled uniformly according to the maximum bending moment at the mid-span, resulting in serious excess of UHPC and steel bars in the low bending moment zone and low material utilization.

[0010] 2. Only thickness direction optimization, lack of transverse gradient: Existing sandwich panels or hollow panels mainly achieve lightweighting and increased load-bearing capacity through cavities or local thickening in the thickness direction, but lack a systematic method to introduce core column density and performance parameter synergistic changes in the transverse direction.

[0011] 3. Lack of quantitative integrated back calculation in the design process: Existing designs rely on multiple rounds of trial calculations and finite element iterations, failing to fully utilize the "approximate linear relationship between bearing capacity and UHPC tensile strength, reinforcement ratio and plate thickness", making it difficult to establish rapid and repeatable cross-sectional parameter back calculation and arrangement principles.

[0012] 4. Disconnect between structural optimization and construction constraints: In variable cross-section or irregular reinforcement schemes, insufficient consideration is given to structural and construction constraints such as minimum slab thickness, rib width difference, and minimum segment length of variable cross-section, resulting in some schemes being theoretically reasonable but difficult to construct efficiently.

[0013] The purpose of this invention is to provide an ultra-high performance concrete core column slab and its integrated design method, which, while meeting the requirements of bearing capacity and stiffness, achieves a precise distribution of UHPC material, steel reinforcement and core column density along the span, taking into account mechanical performance, economy and construction feasibility.

[0014] To achieve the above objectives, the technical solution of the present invention can be summarized as follows:

[0015] (I) Overall Structural Form

[0016] The UHPC core plate of this invention is mainly composed of the following parts (see...) Figures 1-3 UHPC Top Panel UHPC bottom panel UHPC core pillars distributed between the upper and lower panels Longitudinal ribs arranged along the span and forming a joint with the core column Longitudinal tension reinforcement located in the tension zone ; and the distribution of transverse reinforcing bars Supporting components, such as beams or walls ; Across coordinates The direction of the slab span Pure bending segment controlled by peak bending moment Shear span controlled by both shear force and bending moment The UHPC core plate can be a two-way plate or a one-way plate, preferably a one-way plate structure that is mainly subjected to bending in the transverse direction.

[0017] (ii) Transverse Variable Density and Parameter Distribution

[0018] 1. Moment Zoning and Functional Division

[0019] Based on the load conditions of the slab during its service life and under its ultimate bearing condition, the bending moment envelope along the span is calculated. Based on the deflection curve, the slab span is divided into: pure bending segments. The mid-span region where bending moment is close to its peak and shear force is relatively small; the shear span section. The area near the support has a larger shear force and a relatively smaller bending moment.

[0020] 2. Relative density of the core column Transverse variable density control

[0021] UHPC core pillars are arranged between the upper and lower panels. , forming a relative density of Core column domain The relative density is the ratio of the volume of the core column to the total volume of the envelope region of the same volume, satisfying: Furthermore, the control is applied in different cross-sectional regions as follows: pure bending segments near the peak bending moment. Inside, A value close to the upper limit of 5% is used to reduce the core column spacing and improve local bending stiffness and bearing capacity; in the shear span section with smaller bending moment... Inside, Take a value close to the lower limit of 2.5% to appropriately increase the core spacing, reduce weight and material usage. It can be adopted in a continuous variation form (such as increasing from the support to the mid-span according to a smooth function) or in a piecewise constant form (taking constant values ​​within several bending moment intervals).

[0022] 3.Plate thickness With reinforcement ratio Transverse gradient

[0023] Along the cross direction Bottom panel thickness With tensile reinforcement ratio The bending moment distribution changes in tandem, satisfying the following condition: pure bending segment : Appropriately increase the thickness of the bottom panel Increase the tensile reinforcement ratio Prioritize ensuring bending moment bearing capacity and deflection control; shear span Appropriately reduce and While meeting shear force and stiffness requirements and combining appropriate core column density, the self-weight and cost are controlled. The slab thickness and reinforcement ratio can vary continuously or segmentally along the span to form a slab with gradient performance in the span. The minimum thickness of the upper and lower panels at any cross-section is not less than 20 mm to ensure durability and construction safety.

[0024] 4. Approximate linear relationship of bearing capacity and inverse parameter calculation

[0025] Based on experimental and finite element analysis results, this invention establishes an approximately linear or piecewise linear relationship between bearing capacity and UHPC tensile strength, tensile reinforcement ratio, slab thickness, and core column relative density to determine the span position. The expression for the bearing capacity at the location: ,in: : Crossing position Ultimate bearing capacity per unit width at the location; : The effective tensile strength of UHPC at this cross section; : Tensile reinforcement ratio; Thickness of the tension side plate; : Relative density of the core column; The regression coefficients obtained from experiments or finite element parameter analysis can be obtained using a single linear model or several piecewise linear models.

[0026] Given design load effects Moment envelope Under the conditions of deflection limits, the design objective is: in For the safety factor. Through the above approximate linear relationship, the bearing capacity constraint is transformed into a constraint on... The linear or quasi-linear constraints lay the foundation for the inverse calculation of cross-directional parameters.

[0027] 5. Construction and feasibility constraints

[0028] To ensure the overall structural stress coordination and construction feasibility, the following structural constraints are introduced based on the above parameter distribution: the thickness of the upper and lower panels at any cross-section. mm; longitudinal ribs within the same cross section The rib width difference is controlled within a predetermined proportion range, for example, not exceeding a certain percentage of the larger rib width, to ensure the deformation coordination between the slab surface and the ribs and core columns; the minimum control section length of adjacent variable cross-section or variable reinforcement sections is not less than the preset distance to avoid excessively frequent changes in cross-sectional parameters, which would cause complexity in the formwork and difficulty in cutting steel bars; the gradient of changes in slab thickness and reinforcement ratio in adjacent sections is limited so that the rate of change of cross-sectional parameters does not exceed the preset upper limit, thereby avoiding stress concentration and amplification of construction errors.

[0029] (III) Integrated Design Method

[0030] The design method of the present invention is as follows: Figure 4 As shown, the main steps include:

[0031] 1. Loading and Internal Force Analysis

[0032] After determining the building's intended use and load conditions, calculate the bending moment envelope of the UHPC core plate during its service life and under its ultimate bearing condition. Shear force envelope; deflection curve and its limits. The bending moment section is preliminarily divided to obtain the pure bending segment. With the scissor span Position and length.

[0033] 2. Establish a bearing capacity regression model

[0034] Based on existing or specially arranged tests and finite element parameter analysis results, an approximate linear or piecewise linear relationship between bearing capacity and key parameters is fitted, yielding: Furthermore, regression coefficient sets can be determined for different stress sections (such as pure bending sections and shear span sections) to more accurately reflect the synergistic effects of tension, bending, and shear.

[0035] 3. Parameter inverse calculation based on bending moment and deflection constraints

[0036] Constrained by internal force envelope and deflection limit values, at each span position The required inverse calculation: effective tensile strength of UHPC (This can be achieved through localized reinforcement, fiber addition, or prestressing); Tensile reinforcement ratio ;Plate thickness Relative density of the core column In the back calculation process: in the pure bending segment Internally, priority should be given to appropriately increasing and To improve bending moment bearing capacity and stiffness; in the shear span section Internally, while satisfying shear force and overall stiffness requirements, the spacing between core columns can be appropriately increased and the spacing reduced. ,make Approximately 2.5%, achieving economic optimization.

[0037] 4. Structural and construction constraint verification and parameter correction

[0038] The above inverse calculation yields Input the structural and construction constraint module to perform the following checks: minimum slab thickness and panel thickness difference constraints; rib width difference and cross-sectional change gradient constraints; minimum control section length constraints and formwork layout feasibility; core column relative density. The arrangement principle of ensuring that the high bending moment zone is close to the upper limit and the low bending moment zone is close to the lower limit is considered. If it is found that the structural or construction constraints are not met, the relevant parameters are adjusted, and the bearing capacity and deflection are rechecked until both mechanical and construction requirements are met.

[0039] 5. Output integrated design results

[0040] After completing the above iterations, the following are generated: a cross-sectional variable density UHPC core column layout diagram; a variable cross-section layout diagram for the upper and lower panels; and longitudinal and transverse reinforcement diagrams and statistical tables. This achieves integrated optimization of core column density, slab thickness, and reinforcement within the same design process.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. Precise material cross-directional configuration: by adjusting the relative density of the core pillars , plate thickness With reinforcement ratio With bending moment envelope Explicit correlation enables variable density and performance gradient arrangement of core columns, allowing UHPC and steel reinforcement to be concentrated in the high bending moment zone, while reducing the amount of reinforcement in the low bending moment zone.

[0043] 2. Overcoming the limitations of "optimization only in the thickness direction": Unlike traditional hollow boards or sandwich panels that mainly create cavities and local thickening in the thickness direction, this invention introduces a dual gradient of density and performance in the transverse direction, forming a UHPC core board system with significantly differentiated characteristics.

[0044] 3. Fast inverse calculation based on approximate linear relationship: utilizing... The approximate linear relationship transforms the design process from "trial calculation + finite element iteration" to "constraint-driven parameter inverse calculation", improving design efficiency and forming repeatable and programmable design rules.

[0045] 4. Integration of mechanical optimization and construction constraints: During the optimization process, constraints such as minimum plate thickness, rib width difference, minimum control section length, and cross-sectional change gradient are introduced simultaneously, so that the obtained scheme can meet the requirements of load-bearing capacity and stiffness, while also simplifying the formwork layout, facilitating the processing of steel bars, and ensuring on-site construction feasibility.

[0046] 5. Significant economic and comprehensive performance advantages: While ensuring overall stiffness and load-bearing capacity, compared with UHPC core column plates with constant cross-sectional parameters, this invention can effectively reduce the amount of UHPC and steel reinforcement, reduce self-weight, improve structural durability and crack resistance, and has better overall economic performance. Attached Figure Description

[0047] The present invention will be further described below with reference to the accompanying drawings, which are used to illustrate one or more embodiments of the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0048] Figure 1 This is a schematic diagram of the cross-sectional arrangement of the ultra-high performance concrete core column plate of the present invention. —UHPC top panel; —UHPC bottom panel; —UHPC core column; —Longitudinal ribs; —Tension reinforcement; —Horizontal reinforcing bars; —Support (beam or wall); —Slab span direction; —Purely curved section; —Cut the span; — Variable density core arrangement area.

[0049] Figure 2 This is a schematic diagram of the cross-sectional structure of the pure bending section of the present invention. —UHPC top panel; —UHPC bottom panel (relatively thick); —UHPC core pillars (relatively small spacing, high density); —Longitudinal ribs; —Longitudinal tensile reinforcement (high reinforcement ratio); —Horizontal reinforcing bars; —Location marker for pure curve segment.

[0050] Figure 3 This is a schematic diagram of the shear span cross-section structure of the present invention. —UHPC top panel; —UHPC bottom panel (relatively thin); —UHPC core posts (relatively large spacing, low density); —Longitudinal ribs; —Longitudinal tensile reinforcement (low reinforcement ratio); —Horizontal reinforcing bars; —Cut the segment location marker; — Support (indicating the area near the support).

[0051] Figure 4 This is a schematic diagram of the integrated design method of the present invention. —Load and internal force analysis module, used to calculate bending moment, shear force and deflection envelope; —Load-bearing capacity regression model building module, used for fitting coefficients ; —A constraint-based parameter inverse calculation module for solving ; —The construction and construction constraint verification module is used to check plate thickness, rib width difference, minimum control section length and core column density range, etc. —Results output module, used to generate core column layout diagram and reinforcement diagram; arrows indicate the direction of data and process transfer between modules. Detailed Implementation

[0052] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Those skilled in the art should understand that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention; any equivalent substitutions or adjustments made to dimensions, reinforcement, materials, and calculation processes without departing from the concept of the present invention should be considered to fall within the scope of protection of the present invention.

[0053] Example 1: Single-span variable-density UHPC core column floor structure

[0054] This embodiment uses a unidirectional bending UHPC core column floor slab as an example to illustrate the design method of variable density arrangement of core columns and slab thickness and reinforcement gradient based on bending moment distribution. See also Figures 1-3 .

[0055] 1. Basic structural parameters and layout

[0056] like Figure 1 As shown, the floor slab along the span direction Supports spanning both ends This forms a simply supported or continuous floor slab. The slab width is 3.0 m, which can be considered representative of a unit width strip. The main structural components are as follows: UHPC upper panel. Integrated with the floor finishes, it primarily bears the stress in the pressure zone and provides durability and protection; UHPC lower panel. This is the main tension zone, bearing bending moment and tensile stress and reinforced; UHPC core column Longitudinal ribs are arranged along the width and span of the plate, supporting the upper and lower panels and forming a sandwich structure. The rib-like region formed by the core column and the locally widened section enhances the transverse bending stiffness; longitudinal tensile reinforcement. Arranged on the bottom panel With longitudinal ribs Tension side; transverse reinforcement Arranged within the upper and lower panels to form distribution reinforcement and negative moment reinforcement; slab span direction Along the direction of the core column arrangement; pure bending segment Near the mid-span, the peak bending moment region; shear span. : near the support In areas with high shear force and low bending moment; in areas with variable density core column arrangement... The area where all core columns are distributed between the upper and lower panels. Total floor slab span. Take a 12 m slab, a 3.0 m slab width, and supports. It is a reinforced concrete beam or wall, with one or both ends of the slab simply or continuously connected to the support.

[0057] 2. Moment zoning and internal force analysis

[0058] Under known design load conditions such as dead load and live load, the bending moment envelope along the span can be obtained by simplifying calculations using structural analysis software or specifications. Shear force envelope and deflection curve. Taking a simply supported uniformly distributed load as an example, its maximum bending moment is approximately: ,in The design incorporates uniformly distributed loads.

[0059] According to the income Shape, span Divided into: middle 0.4 to 0.5 The area is a pure bending segment The bending moment is close to its peak value, while the shear force is relatively small; approximately 0.25–0.3 at each end. Region as a scissor span When the shear force is large, the bending moment decreases towards the support.

[0060] This partition is for illustrative purposes only; the actual layout can be adjusted according to specific circumstances. The shape and control bending moment range were optimized and determined.

[0061] 3. Relative density of the core column Transverse variable density arrangement

[0062] like Figure 1 As shown, in the variable density core arrangement area Inside, UHPC core pillars are arranged between the upper and lower panels. Define local relative density. This refers to the percentage of the UHPC core column's solid volume within an envelope of a certain length and width at that location. In this embodiment, Controlled at: The specific distribution rule is as follows: in the pure bending section at mid-span... inside, take Core column The spacing is relatively small, such as 150–200 mm; shear span transition zone The percentage decreased smoothly from 5.0% to approximately 2.5%–3.0% in a linear or piecewise linear manner; near the support. The cut span area, The spacing between the core posts increases, such as to 250–300 mm.

[0063] The spacing between adjacent core column rows can be controlled along the span using a segmented constant value method, for example: 0.4 at the mid-span. Within the specified range: longitudinal spacing of core posts 180 mm; transition zone 0.1 mm each. The diameter increases linearly from 180 mm to 260 mm; 0.4 mm remains near the support. The longitudinal spacing between the core columns is 260 mm. Through the above segmented and gradual design, both structural performance and ease of construction can be achieved.

[0064] 4. Plate thickness With reinforcement ratio Transverse gradient settings

[0065] (1) Plate thickness distribution

[0066] like Figure 2 and Figure 3 As shown, the lower panel thickness In pure curves and cut span Using different values: pure bending segment ( Figure 2 ): Bottom panel thickness Take 50-60 mm; top panel thickness 40-50mm is acceptable; longitudinal ribs In the core column The location should be appropriately widened or thickened to improve local bending stiffness.

[0067] Cutting the span ( Figure 3 ): Bottom panel thickness The minimum thickness constraint can be appropriately reduced to 35–45 mm, but not less than 20 mm; top panel The thickness is basically similar to or slightly reduced from the pure bending section; the plate thickness is from the shear span section. Towards pure curve When gradually changing the thickness, the thickness difference and slope of the change between adjacent sections should be controlled. For example, each control section should be 1.0 to 1.5 m long, and the thickness difference between adjacent sections should not exceed 10 mm to facilitate the processing of formwork and reinforcing bars.

[0068] (2) Distribution of tensile reinforcement ratio

[0069] Longitudinal tensile reinforcement reinforcement ratio Different treatment for different sections:

[0070] pure curve Based on the peak bending moment and deflection control requirements, a higher reinforcement ratio, such as 1.0% to 1.5%, should be adopted; the diameter and spacing of the reinforcing bars can be as follows: ~ mm.

[0071] Cutting the span Because the bending moment is small, it can be Reduced to 0.5%–0.8%, such as ~ mm; additional reinforcement may be added near the support to cope with negative bending moment or local punching shear, if applicable.

[0072] In the transition section from mid-span to support, the principle of segmented variation can also be adopted to ensure that the reinforcement ratio of adjacent sections changes gradually and the specifications of the steel bars should not be changed too frequently. This can be achieved by adjusting the spacing of the steel bars.

[0073] 5. Application of the approximate linear relationship of bearing capacity and parameter inverse calculation in this embodiment

[0074] In this embodiment, the following bearing capacity regression model is adopted: The meanings of the parameters are as described above. Regression coefficients are obtained through preliminary experiments or finite element parameter analysis, for example: : Reflects the contribution of UHPC tensile strength to load-bearing capacity; : Reflects the influence of the tensile reinforcement ratio; : Reflects the impact of plate thickness variation on overall stiffness and load-bearing capacity; : Reflects the incremental effect of the relative density of the core column on the load-bearing capacity and stiffness.

[0075] During the design, the design load effect is taken into account. The bending moment and deflection generated therefrom are used as constraints, requiring: In conjunction with deflection limit constraints, for Solve the problem.

[0076] In this embodiment, the following strategy can be adopted: in pure bending segments First, determine that the relative density of the core column is close to the upper limit. ;in accordance with Inverse calculation with deflection control and If the calculation shows that the pure bending segment requires mm Only then can it be satisfied With deflection requirements; in the shear span First Control it between 2.5% and 3.0%, and make Approximate the smaller allowable value, such as 40 mm; then, based on the local bending moment and shear force, adjust accordingly. Slight adjustments can be made, such as 0.7% to 0.8%, to meet load-bearing and crack control requirements.

[0077] The result obtained through the above process The distribution is the result of the transverse variable density and functional gradient design in this embodiment.

[0078] 6. Feasibility verification of construction and building.

[0079] After obtaining the preliminary parameter distribution, this embodiment further verifies the following structural and construction constraints:

[0080] Minimum plate thickness constraint: The thickness of the upper and lower panels at any position is not less than 20 mm. In this embodiment, the thickness of each section is not less than 20 mm. and All are greater than 35 mm, which meets the requirements.

[0081] Rib width difference and cross-sectional compatibility: longitudinal ribs There may be a difference in width or height between the pure bending section and the shear span section. In this embodiment, it is specified that the difference in rib width within the same cross section shall not exceed 30% of the larger rib width, and the deformation coordination between the plate surface, ribs, and core column is ensured by appropriately adjusting the rib cross section size.

[0082] Minimum control section length and variation gradient: The minimum control section length for changes in slab thickness and reinforcement is 1.0 to 1.5 m. The difference in slab thickness between adjacent sections is controlled within 10 mm, and the variation in reinforcement ratio between adjacent sections does not exceed 0.2%, thereby avoiding excessively frequent changes in cross-sectional parameters that would lead to overly complex formwork and reinforcement processing.

[0083] Core column relative density range and zoning: calculated across the entire span. All values ​​fall within the range of 2.5% to 5%, with the peak bending moment range being close to 5% and the smaller bending moment range being close to 2.5%, which meets the key feature requirements of this invention.

[0084] After the above verification is completed, construction drawings can be generated, including detailed drawings of the variable density core column layout, schematic diagram of slab thickness variation, and detailed reinforcement drawings, which serve as the final design results of this embodiment.

[0085] II. Example 2: Integrated Design Method Based on Software Implementation

[0086] This embodiment aims to implement the method of the claims, illustrating how, with the aid of a computer program or engineering software, parameter distribution and reinforcement scheme of a variable-density UHPC core column slab can be automatically generated based on the input bending moment distribution and design constraints. See also... Figure 4 .

[0087] 1. System Composition and Functional Modules

[0088] like Figure 4 As shown, the design system includes the following functional modules: Module Load and internal force analysis module; module Module for establishing a bearing capacity regression model; Constraint-based parameter inverse calculation module; module Construction and building constraint verification module; Result output module. The above modules can be integrated into the same engineering design software, or they can work together through several independent programs.

[0089] 2. Design Process

[0090] (1) Load input and internal force analysis (Module 12)

[0091] Designers in modules Input: plate span Slab width, support conditions and constraint methods; basic mechanical parameters of UHPC material, steel reinforcement grade; combinations of dead load, live load, prestressed load, etc.

[0092] Module Automatically builds a calculation model and outputs the bending moment envelope along the span direction. Shear force envelope; deflection curve and its maximum value. And automatically define pure bending segments. With the scissor span The location can prompt the user to make fine adjustments.

[0093] (2) Selection and calibration of bearing capacity regression model (Module 13)

[0094] Module Several preset linear or piecewise linear regression model formats are provided, and users can select the appropriate model according to the type of project, such as a uniform linear model: Alternatively, piecewise linear models with different coefficient sets can be used for the pure bending segment and the shear span segment.

[0095] Users can import: experimental data; finite element parameter analysis results; historical engineering calibration data. Module Automatic solution using fitting methods such as least squares method. It also provides an evaluation of the fitting accuracy. If the fitting accuracy is insufficient, it prompts the user to adjust the parameter space or supplement the data.

[0096] (3) Constraint-based parameter inverse calculation (Module 14)

[0097] In the module In the process, users set goals and constraints, such as: safety factor. Permissible deflection limits; maximum and minimum plate thicknesses UHPC tensile strength adjustable range ; List of optional rebar diameters and spacings; Allowable range of core column relative density .

[0098] Module For each discrete position The following optimization problem is established: In satisfying: Under the premise of deflection constraints, minimize a certain objective function, such as material cost or total weight. To simplify practical engineering applications, the module can adopt the following strategy: in pure bending sections... ,fixed Near the upper limit, adjust , To meet the requirements of load-bearing capacity and deflection; in the shear span section Prioritize Drop to near the lower limit, by adjusting a smaller amount , To meet the requirements. Optimization solution obtains the result for each position. corresponding Initial solution.

[0099] (4) Verification and correction of construction and building constraints (Module 15)

[0100] Module According to the preset construction rules, the initial solution is smoothed and corrected, including:

[0101] Difference between minimum board thickness and panel thickness: Correction not satisfied The cross-section is mm; if the thickness difference between the upper and lower plates is too large, adjust the thickness of the upper plate appropriately to make it compatible with the lower plate.

[0102] Rib width difference and cross-sectional gradient: control the rib width difference within the same cross-section to not exceed a certain proportion; for adjacent... The plate thickness and reinforcement ratio at each point are smoothed to ensure that the parameter change rate does not exceed the preset upper limit.

[0103] Minimum control segment length: This involves dividing several adjacent segments into... Points are grouped into segments with a length not less than the preset minimum control segment length, and uniform slab thickness, reinforcement and core column spacing are adopted within the segments.

[0104] Core column relative density upper and lower limits: restricting all cross-sections The bending moment should fall within the range of 2.5% to 5%, ensuring an overall distribution trend where the peak bending moment section is close to 5% and the lower bending moment section is close to 2.5%. If, after correction, some sections no longer meet the load-bearing or deflection requirements, the module... Automatic callback module Local re-optimization is performed until the two-dimensional constraints—mechanical safety and construction feasibility—are met.

[0105] (5) Result output (Module 16)

[0106] Module The final parameter distribution is converted into structural construction drawings and design specifications, including: a cross-sectional variable density core column layout diagram, showing the core column spacing, arrangement, and relative density for each section; and a variable cross-section layout diagram, indicating the slab thickness for each section. rib section dimensions; reinforcement diagram: listing the longitudinal reinforcement of different sections according to the specification. Combination and transverse reinforcement; material usage statistics and economic comparison: material and cost comparison with the UHPC core column plate scheme with equal cross-section.

[0107] The module can generate CAD files or BIM models, facilitating collaborative design with other disciplines.

[0108] III. Example 3: Variant Implementation of Bridge Deck Engineering Application (Optional)

[0109] In bridge engineering, the variable-density UHPC core plate of this invention can be used as a bridge deck or orthotropic slab top plate. Similar to Embodiment 1, but with the following differences: Support It can be a steel or concrete main beam, span direction of the slab. Possibly a multi-span continuous structure; bending moment envelope Controlled by traffic load, pure curve section and cut span The distribution is more complex and can be combined with multi-lane load combinations; UHPC tensile strength The control can be achieved through zoned casting with different fiber content or local prestressing reinforcement; near the piers, additional consideration needs to be given to the effects of temperature gradient and braking force, which can be addressed in modules. Additional working conditions are added to obtain a safer variable density and reinforcement scheme.

[0110] Apart from the differences mentioned above, its design process and construction principles are basically the same as those of Embodiment 1 and Embodiment 2, and will not be repeated here.

[0111] As can be seen from the above embodiments, without changing the basic structural form of the UHPC core column plate, the present invention introduces a cross-sectional variable density core column based on bending moment distribution and a coordinated design with plate thickness and reinforcement gradient. It also establishes an integrated design process of "bending moment envelope - parameter back calculation - structural constraints - construction feasibility" through an approximate linear bearing capacity model, which can significantly improve the material utilization efficiency and engineering feasibility of the UHPC core column plate structure.

Claims

1. A high-performance concrete core column slab, characterized in that, include: The upper and lower UHPC panels and multiple rows of UHPC core columns arranged between the two panels, wherein the core column slab is set as a pure bending segment and a shear span segment along the span direction, and satisfies: 1) the core column spacing, slab thickness and tensile reinforcement ratio vary with the span position and are based on the design bending moment envelope. 1) The spacing between the pure bending section and the shear span section varies either separately or continuously; 2) In the pure bending section, the core column spacing decreases relative to the shear span section, while the slab thickness and tensile reinforcement ratio increase relative to the shear span section; 3) In the shear span section, the core column spacing increases relative to the pure bending section, while the tensile reinforcement ratio decreases, in order to control the slab's self-weight and material usage; 4) The relative density of core columns within any local section. The core column density is controlled between 2.5% and 5%, with the upper limit of close to 5% in the peak bending moment range and the lower limit of close to 2.5% in the smaller bending moment range, thus achieving cross-sectional variable density arrangement.

2. The ultra-high performance concrete core column plate according to claim 1, characterized in that, The relative density of the core column , plate thickness and the ratio of tensile reinforcement The performance gradient plate is formed by continuous changes in the span position, or by segmenting the plate into several span sections according to the bending moment variation law.

3. The ultra-high performance concrete core column plate according to claim 1 or 2, characterized in that, The minimum thickness of the upper and lower panels at any cross section shall not be less than 20 mm, and the difference between the widths of each rib within the same cross section shall be limited to a predetermined ratio range to ensure overall deformation coordination between the panel, ribs and core column.

4. The ultra-high performance concrete core column plate according to any one of claims 1 to 3, characterized in that, The span length of adjacent variable cross-section or variable reinforcement sections shall not be less than the preset minimum control section length, so as to reduce the number of changes in cross-section parameters and improve construction feasibility.

5. The ultra-high performance concrete core column plate according to any one of claims 1 to 4, characterized in that, The UHPC core and panel are connected by integral casting or assembly, so that the axial force of the core and the bending deformation of the panel work together.

6. A method for integrated design of ultra-high performance concrete core column slabs, characterized in that, The steps include: (1) Calculate the bending moment in the span direction of the slab based on the load conditions of the slab during its service stage and under its ultimate bearing state. (1) Shear force and deflection envelope; (2) Using the approximate linear relationship between bearing capacity and UHPC tensile strength, tensile reinforcement ratio, slab thickness and core column relative density, establish the bearing capacity expression. (3) Using the internal force envelope and allowable deflection limit as constraints, for each span position Required UHPC tensile strength Reinforcement ratio , plate thickness Relative density of core column Perform reverse calculation; (4) Perform structural constraints and construction feasibility checks on the obtained parameters, including minimum plate thickness, rib width limit, minimum control section length and core column relative density range of 2.5% to 5%, etc. If not satisfied, adjust the parameters and recheck; (5) Output cross-sectional variable density core column layout diagram and steel reinforcement diagram to complete the integrated design of UHPC core column plate.

7. The design method according to claim 6, characterized in that, The bearing capacity expression in step (2) is a linear regression or piecewise linear regression model, and the regression coefficients It is obtained by fitting experimental data or finite element parameter analysis results.

8. The design method according to claim 6 or 7, characterized in that, In the back calculation process of step (3), priority is given to increasing the value of the pure bending segment. and To meet the requirements for bending moment bearing capacity and deflection, priority should be given to adjusting the shear span section. and To meet the comprehensive requirements of shear force, stiffness and economy.

9. The design method according to any one of claims 6 to 8, characterized in that, The structural constraints in step (4) also include the control of the gradient of the change in plate thickness and reinforcement ratio of adjacent sections, so that the rate of change of cross-sectional parameters does not exceed the preset upper limit, in order to avoid stress concentration and amplification of construction errors.

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