Mechanical Performance of Square Box-Type Core Mold Hollow Floor Slabs Based on Field Tests and Numerical Simulation

Abstract

This study investigates the mechanical performance and failure mechanisms of large-span, cast-in situ hollow-core floor slabs with square-box core molds under vertical loading. A combination of in situ tests and refined numerical simulations was used to investigate the slab’s behavior. An 8 m × 8 m hollow slab from the Xinluzhou Industrial Park in Hefei, China, was subjected to five-stage cyclic loading up to 9.0 kN/m² using a distributed water tank system. Real-time strain monitoring showed that the slab remained within the elastic range, exhibiting a linear strain-load relationship and bidirectional bending stiffness, with less than 5% deviation between the X and Y directions. Finite element analysis, incorporating a concrete plastic damage model and a bilinear steel model, replicated the experimental stress distribution, with errors of less than 6.9% for reinforcement and 8.8% for concrete. The simulation predicted an ultimate load-bearing capacity of 27.2 kN/m², with initial failure indicated by diagonal cracks at the column capital edges, followed by flexural cracks at the slab mid-span. These findings clarify the bidirectional bending behavior and stress redistribution, characterized by “banded gradient” and “island-shaped” stress zones. This study provides valuable insights and design optimization strategies to improve the structural performance and safety of hollow-core floor slabs in high-rise buildings.

1. Introduction

Floor slabs are fundamental components in building structures, significantly impacting both functional utility and overall cost [1,2]. As building spans increase, the self-weight of floor slabs typically increases as well. This increase not only limits the efficient use of architectural space but also constrains the realization of desired building functions. Consequently, reducing the self-weight of floor slabs during design has become a critical challenge [3,4,5]. Cast-in situ hollow core slabs, an innovative structural form, significantly reduce self-weight by incorporating hollow sections within the slab core, while also enhancing mechanical performance. This system has been widely applied in various construction projects [6,7]. Beyond reducing slab weight, this structure also improves seismic resistance and thermal performance, making it particularly suitable for large-span slab design [8,9,10]. However, despite their extensive practical application, the structural behavior of cast-in situ hollow core slabs, especially the deformation characteristics under actual loading conditions of slabs with rectangular box core molds, has not been sufficiently validated through comprehensive tests. To fully understand the stress distribution in reinforcement and concrete, strength reserves, and safety performance of hollow core slabs under load, detailed investigation and validation through in situ testing are essential [11,12,13,14].

Researchers have extensively studied the mechanical properties, construction techniques, material selection, and design optimization of cast-in-place concrete hollow-core floor slabs. Ghamry et al. [15] proposed a layered hollow-core slab structure that combines high-strength concrete with lightweight aggregate concrete to optimize the weight-to-strength ratio. Through four-point bending tests and finite element analysis, the effects of various parameters on slab performance were analyzed. Sayhood [16] introduced an empirical equation to predict the shear strength of reinforced concrete deep beams, focusing on improving existing codes’ accuracy. Sagadevan et al. [17] experimentally compared the performance of square box and spherical core molds, showing that square box-shaped core molds are more effective in utilizing membrane tension to enhance bearing capacity. Mahboob et al. [18] summarized construction techniques for cast-in-place concrete hollow-core slabs, providing solutions to improve project quality and efficiency. Firouzranjbar et al. [19] analyzed the design of these slabs, emphasizing the effective combination of structural forms and mechanical performance. As research progresses, more scholars have focused on the vertical load-bearing characteristics and design methods of hollow-core slabs. Prakashan et al. [20] proposed new design parameters based on their study of vertical load-bearing characteristics, providing a theoretical foundation for engineering applications. Finite element analysis has been widely used to simulate the mechanical behavior of hollow-core slab structures [21]. For example, Xiangqiang Zeng et al. [22] used finite element methods to analyze hollow-core slabs, while Junyan Jin et al. [22] verified the accuracy of finite element predictions through experimental results. These studies have contributed valuable theoretical and practical knowledge for the construction and design of hollow-core slabs.

To verify the rationality and safety of hollow core slab structural designs, this study combines in situ testing with finite element simulations to assess deformation characteristics and stress distribution under vertical loading [23]. The experimental monitoring provides a deeper understanding of the load-bearing mechanism of hollow core slabs, offering a scientific basis for design optimization [24]. This research also evaluates the influence of construction quality on slab performance, contributing to future engineering projects and innovations in structural design and construction techniques.

2. Project Overview

Building 1 of the Hefei Xinluzhou Integrated Circuit Industrial Park is a high-rise structure located at the northeast corner of the intersection between Tianshui Road and Jinchi Road in the Luyang Economic Development Zone, Hefei, China. The site is characterized by high urban density and heavy traffic. The building consists of one basement level and 24 above-ground stories, reaching a total height of 96.35 m, as shown in Figure 1a. The primary structural system adopts a frame-core tube configuration. The floors utilize cast-in situ hollow-core slabs with square-box core molds, as illustrated in Figure 1b,c.

The hollow-core slab is connected to the steel-reinforced concrete cast-in-place columns through main beams, with core molds arranged at even intervals in the interior region according to the design. The core molds are prefabricated products made of expanded polystyrene (EPS) plastic, with a thickness of 12 mm. The lower layer consists of bottom reinforcement, while the upper layer consists of top reinforcement, with the two layers connected by inter-beam reinforcement. When the hollow core slab thickness is 350 mm, core molds with dimensions of 650 mm (length) × 650 mm (width) × 230 mm (height) are employed. When the slab thickness is 300 mm, core molds measuring 650 mm × 650 mm × 180 mm are used. For a slab thickness of 270 mm, core molds sized 650 mm × 650 mm × 160 mm are utilized.

The dimensions of the hollow floor slab are 8000 mm × 8000 mm, with a thickness of 300 mm, including a top slab thickness of 60 mm, and double-layer bidirectional surface reinforcement with an 8 mm diameter and 150 mm spacing. The bottom slab thickness is 60 mm. The cross-sectional dimensions of the rib beams are 150 mm × 180 mm, with longitudinal spacing of 800 mm and transverse spacing of 800 mm. The concrete strength grade is C30 (with a standard compressive strength of 30 MPa). Both the reinforcement on the slab surface and the rib beam reinforcement are of HRB400 grade (hot-rolled ribbed steel bars with a yield strength of 400 MPa), while the stirrups are of HPB300 grade (hot-rolled plain steel bars with a yield strength of 300 MPa). The detailed structural layout of the hollow floor slab is shown in Figure 2.

3. In Situ Experiment of the Box-Shaped Hollow Floor Slab

3.1. Experiment Plan

3.1.1. Overview of Experimental Instruments and Equipment

The in situ experiment on the load-bearing deformation characteristics of the box-shaped hollow floor slab was conducted on the 15th floor of Building 1 at the Hefei Core Luchou Integrated Circuit Industry Park, within an 8.0 m × 8.0 m area. The test program involved measuring the stress and strain of both reinforcement and concrete in the primary and secondary ribs, as well as in the top and bottom cast-in situ concrete cover slabs of the floor. Additionally, concrete surface cracks on the slab were monitored. The primary instrumentation included static strain gauges, along with supporting hardware and software, reinforcement strain gauges, concrete surface strain gauges, and concrete crack observation instruments (measurement accuracy: 0.02 mm), as shown in Figure 3.

3.1.2. Mechanical Properties of Engineering Materials

During the on-site testing, concrete specimens and reinforcement samples were collected for laboratory determination of material strength. These specimens were randomly selected from the on-site tests and were identical to the materials used in both the experiment and construction, ensuring the generality, accuracy, and authenticity of the experimental materials. A set of concrete specimens was randomly selected on-site and cured under the same conditions as the experimental floor slabs. After 28 days, tests on the concrete and reinforcement strength were conducted, with the results for both steel bars and concrete strength shown in

Table 1. Concrete strength test results.

No.	Cube Size (mm)	Applied Load (KN)	Compressive Strength (MPa)	Average Strength (MPa)
1	150 × 150 × 150	900.93	34.53	34.66
2	150 × 150 × 150	908.75	34.79

and

Table 2. Reinforcement strength test results.

No.	Yield Strength (MPa)	Tensile Strength (MPa)	Maximum Load (KN)
1	416	550	184.16
2	435	572	186.23

below.

For the reinforcement, 20 mm diameter ribbed bars were selected for testing.

The strength data in the tables show that both the reinforcement and concrete materials meet the design code requirements, satisfying the strength specifications for materials used in the project.

3.2. Experimental Methods

This study used an in situ loading test system to evaluate the structural response of the rectangular box-core hollow slab. The testing procedure consisted of three main stages: monitoring system installation, staged loading, and structural response monitoring.

3.2.1. Monitoring System Installation

Based on the bidirectional flexural behavior of the structure and in accordance with the Standard for Test Methods of Concrete Structures (GB/T 50152-2012) [25], strain monitoring points were established in the critical load-bearing zones of the primary and secondary rib beams and the cast-in situ concrete thin slabs on both the top and bottom surfaces of the slab. During the reinforcement installation stage for the primary and secondary rib beams and the thin slabs on the top and bottom surfaces of the slab, rebar stress gauges were welded onto the rib beam reinforcement at the designated test points (see Figure 4a). Simultaneously, concrete strain gauges were installed on the slab reinforcement at the corresponding test points during concrete pouring. After completing concrete pouring and the required curing period, concrete strain gauges were bonded to the concrete surface at the corresponding test points (see Figure 4b).

3.2.2. Implementation of Graded Loading

A distributed water tank loading system was used at the test site to simulate uniform vertical loads, with the maximum load reaching 45.2% of the total design load (19.9 kN/m²), i.e., 9 kN/m². The water tanks were symmetrically arranged on an orthogonal grid over the 8.0 m × 8.0 m test area. A central 1 m-wide access corridor was included within the loading system (see Figure 5a) to facilitate water filling operations and real-time monitoring. The test used a five-level cyclic loading-unloading system, starting with a 1.0 kN/m² preload to eliminate contact nonlinearity. The load was then incrementally increased by 2.0 kN/m², reaching peak values of 3.0, 5.0, 7.0, and 9.0 kN/m², before being unloaded in stages, from 7.0 kN/m² to 0.0 kN/m². According to the Chinese standard GB/T 50152-2012 [26], each load stage was applied or removed and maintained for 30 min to ensure that the structural stress redistribution reached a steady-state balance, as shown in Figure 5b.

3.2.3. Structural Response Monitoring

During the loading process, the floor slab surface was closely monitored for visible cracks in the concrete. Simultaneously, strain variations in both the rebar and concrete were monitored to fully capture the structural response (see Figure 6a). After loading was completed, a concrete crack tester measured the crack width, as well as the length, number, and distribution characteristics of potential cracks (see Figure 6b). The test results showed that under a maximum load of 9.0 kN/m², no visible cracks appeared on the floor slab surface, the crack width was zero, and the distribution was uniform, with no abnormal concentration.

3.3. Experimental Results and Analysis

The load–strain curve of the rib beam reinforcement for the hollow floor slab is shown in Figure 7. The specific measurement points include the upper reinforcement at the center of the X-direction hidden beam span (S1), the bottom center measurement point (S3), the quarter of the Y-direction hidden beam (S8), and the lower reinforcement at the center of the X-direction hidden beam span (X1), the bottom center measurement point (X3), and the quarter of the Y-direction hidden beam (X8). Note that the strain values of the rebar are derived from the measured stress values. This conversion follows Hooke’s law (Equation (1)):

$$\epsilon ={\displaystyle \frac{\sigma }{E}}$$

(1)

where

• E—Elastic Modulus,
• σ—Stress,
• ε—Strain

This conversion ensures direct comparability with concrete strain data and provides a unified benchmark for validating the interaction between rebar and concrete.

Figure 7. Load–strain curve of the rib beam reinforcement under vertical staged loading (yielding strain: 200 μϵ).

Figure 7. Load–strain curve of the rib beam reinforcement under vertical staged loading (yielding strain: 200 μϵ).

As seen in the figure, the upper rib beam reinforcement exhibits compressive behavior under load, with the maximum strain occurring at the center of the span. The strain decreases from the center of the slab towards the edge rib and further decreases towards the two sides. Additionally, the strain in the upper reinforcement of the center slab changes from positive to negative, indicating that before the load was applied, the upper reinforcement of the slab ribs was under tensile stress. As the load increased, it gradually transitioned to compressive stress. The stress–strain behavior of the lower reinforcement in the rib beam of the box-shaped core mold hollow floor slab is the opposite of that of the upper reinforcement. Under load, the lower rib beam reinforcement is in a tensile state, with strain decreasing from the center of the slab towards the edge rib and further reducing towards both sides. The strain in the lower reinforcement of the center slab rib changes from negative to positive, indicating that initially, the lower reinforcement of the slab rib was under compressive stress. As the load increases, the lower reinforcement transitions to tensile stress. This phenomenon is hypothesized to be related to the upward camber effect applied to the slab during formwork installation, as required by the construction specifications.

The load–strain relationship for the hollow floor slab concrete is shown in Figure 8. Figure 8 shows the structural response of the bottom slab concrete at key measurement points, including the Y-direction hidden beam center points (HX1, HY1), center points (HX3, HY3), and X-direction hidden beam 1/4 span points (HX8, HY8), load–strain curves.

The figure shows that the hollow floor slab exhibits distinct load distribution characteristics under loading. The top slab concrete is under compression, while the bottom slab concrete is under tension. The strain data from each measurement point show a linear trend with the load, indicating that the floor slab remains in the elastic stress stage under a 9.0 kN/m² load. During the staged loading up to the 9.0 kN/m² ultimate load and the complete unloading process, the surface of the floor slab was thoroughly inspected visually and scanned with a crack observation instrument, with no visible macro cracks observed. This phenomenon is corroborated by the linear characteristics of the strain data, confirming that the structure remains in an elastic state under the test load. The data from different measurement points show banded variations, closely related to the load-bearing characteristics and structural features of the hollow floor slab. Strain is most noticeable in the loaded areas, gradually concentrating from the boundary to the center of the span, with strain values progressively increasing. Additionally, the stress near the edge ribs increases as the slab ribs are approached, forming an island-like stress concentration, consistent with the stress distribution principle of hollow floor slabs. The strain variation at the concrete measurement points is consistent with the variation in the corresponding rib beams and surface reinforcement, reflecting the collaborative effect of reinforced concrete. Overall, the strain differences between the top and bottom slab concretes and the measurement points in the X and Y directions are minimal, indicating that the hollow floor slab has similar bending stiffness in both directions.

4. Numerical Calculation Analysis of the Box-Shaped Hollow Floor Slab

4.1. Model Construction

4.1.1. Material Constitutive Relationship

In this study, a plastic damage model is used for the concrete constitutive model, in compliance with the relevant standards [26,27]. This model effectively describes the mechanical behavior of concrete under both monotonic and cyclic loading. The rebar constitutive model is an elastoplastic bilinear model. The mechanical performance indicators for concrete and rebar are shown in

Table 3. Material performance indicators.

Material	Grade	Density (kN/m3)	Elastic Modulus (GPa)	Poisson’s Ratio
Concrete	C30	24	30	0.2
rebar	HRB400	78	200	0.3

. The uniaxial compressive stress–strain curve is established using the standard formula. When using the plastic damage model for numerical simulation, as per the Code for Design of Concrete Structures GB 50010-2010 [27], five parameters must be input: expansion angle, eccentricity, compressive strength ratio f_b0/f_c0 (axial compressive strength to cube compressive strength), the ratio of the second stress invariant in the meridian plane for tension and compression (K), and the viscous coefficient. The remaining parameter values are shown in

Table 4. Parameter indicators of plastic damage model.

Expansion Angle (mm)	Eccentricity	fb0/fc0	K	Viscous Coefficient
30	0.1	1.16	2/3	0.005

.

4.1.2. Model Establishment

A three-dimensional finite element numerical model of the box-shaped hollow floor slab was established based on the actual project of Building 1 at the Hefei Core Luchou Integrated Circuit Industry Park. The model uses a separated modeling approach, where rebar and concrete are modeled as separate modules to form three-dimensional components. These components are then assembled using the Assembly function, and repeating components are efficiently generated using the linear array function. Boolean operations merge components of the same type into the overall structure, forming the structural assembly model shown in Figure 9. Key parameters, such as the column capital (800 mm × 800 mm), core mold (650 mm × 650 mm × 130 mm), and hidden beams (150 mm × 600 mm, spacing 800 mm), were set based on the actual engineering dimensions to form a complete structural model. Material and cross-sectional properties were defined in the Property module, and section properties were assigned to the components. The analysis steps were defined in the Step module. The interaction between concrete and rebar is defined in the Interaction module. The embedded element technique embeds rebar into concrete, simulating the coupling relationship between rebar and concrete and accurately modeling the reinforcement effect and constraint behavior of rebar under concrete compression. The loading method is surface load application, with vertical loads uniformly applied to the top slab surface. The boundary conditions are fixed at the column ends (constraint U3 = 0, allowing UR1 and UR2 to remain free), simulating the structural constraints at the column base in actual engineering. In the numerical model, concrete is represented using C3D8R (three-dimensional 8-node linear brick) solid elements, while rebar is represented using T3D2 (three-dimensional 2-node truss) elements. The mesh sizes for concrete and rebar elements are set to 200 mm and 100 mm, respectively. Complex cavity structures are meshed to ensure computational efficiency and accuracy.

4.2. Simulation Results and Analysis

This section conducts numerical calculations based on finite element simulations to systematically evaluate the load response characteristics of the box-shaped core mold hollow floor slab in the elastic stage. The calculations refer to the on-site experimental conditions and numerically reproduce the loading conditions through incremental staged loading. Stepwise uniform loads are applied to the top slab surface: 1.0 kN/m², 3.0 kN/m², 5.0 kN/m², 7.0 kN/m², and 9.0 kN/m². The loading system is designed to quantitatively analyze the structural stiffness degradation pattern and stress redistribution path, providing theoretical support for validating the observed experimental phenomena.

4.2.1. Rebar Strain Analysis

Under the four-edge simple support constraint, the rebar strain distribution in the hollow floor slab under a 9.0 kN/m² uniformly distributed load is shown in Figure 10. The rebar strain cloud diagram shows that under the test load and loading mode, the rebar stress–strain diagram exhibits a distinct island-shaped distribution trend. The rebar strain concentrates towards the column capital area, showing positive strain and radiating outward with decreasing strain, characteristic of island-shaped radiation. The rebar stress cloud diagram shows that under the uniformly distributed load, the center part of the rebar mesh bears compressive stress, while the edge parts (near the column capital) bear tensile stress. The stress cloud diagram changes uniformly and exhibits an axisymmetric pattern, aligning with the bidirectional bending stress state of the hollow floor slab.

4.2.2. Concrete Strain Analysis

The stress cloud diagrams for the top and bottom concrete slabs of the hollow floor slab are shown in Figure 11. The center of the top slab is under compression, transitioning to tension towards both sides. Similarly, the center of the bottom slab is under tension, transitioning to compression towards both sides. Strain increases closer to the column capital. Due to the vertical connection between the column capital and the floor slab, strain concentration occurs at the edges, aligning with the bidirectional bending stress state of the hollow floor slab. Due to internal cavities, the strain contour lines are not smooth and distort at the core mold edges, indicating that the cavity weakens the continuity of the concrete. Comparing the strain distribution cloud diagrams in the X and Y directions shows that their overall trends are highly consistent. This result strongly proves that the hollow floor slab has similar bending stiffness in both the X and Y directions, aligning with the design expectations of bidirectional bending.

4.2.3. Ultimate Load Capacity Analysis of the Hollow Floor Slab

The total load in the experiment reached 9.0 kN/m². Due to limitations of the testing site and equipment, the floor slab was not loaded to failure, and its ultimate load capacity was not directly measured in the experiment. Further research on its load capacity beyond 9.0 kN/m² was conducted, with finite element simulation proven to be a supplementary method [28]. To investigate the ultimate load capacity of the hollow floor slab, the load was continuously increased until the calculation failed to converge, indicating the load at the time of slab failure. In the finite element model of this structure, the calculation reached TIME 4.2, where the structural deformation became excessive. When the next load increment was attempted, the structure could no longer carry the load, and the load at this point is considered the plastic limit load, which is 27.2 kN/m². To further compare the crack distribution, this study used the tensile damage index (DAMAGET) as the core parameter [29]. The crack distribution of the hollow floor slab at this point is shown in Figure 12.

The figure shows that cracks are mainly concentrated in the middle of the bottom span and at the edge of the column capital at the top of the slab, corresponding to the maximum positive and negative bending moments of the slab. Additionally, diagonal cracks appear at the intersections of the slab corners and columns. Cracks first appear at the slab-column junction. In the middle of the bottom span, cracks first appear vertically along the box-shaped cavity units. The design should focus on strengthening the bending and punching shear resistance around the column capital and optimizing the core mold spacing in the center span to delay crack propagation.

4.3. Comparison Analysis of Experiments and Finite Element Simulation

To further explore the load-bearing characteristics of the box-shaped core mold hollow floor slab and verify the reliability of the finite element model, this study compares experimental and numerical simulation results based on the strain gradient distribution theory, selecting representative key monitoring points.

The center point of the rebar mesh (center span, corresponding to test point S3) was selected for comparison. The comparison results are shown in Figure 13. Under the 9.0 kN/m² load, the experimentally measured rebar strain was 13 με, while the finite element simulation value was 12.1 με, with a relative error of 6.9%, indicating a high degree of agreement. The finite element simulation successfully captured the core feature of rebar stress—the “island-shaped radiation” distribution pattern, where tensile strain concentrates in the column capital area and spreads outwards, decreasing. This feature is consistent with the experimentally measured strain gradient distribution, effectively verifying the model’s accuracy in simulating the rebar stress state. In the finite element simulation, the embedded element technique was used to model the rebar-concrete interaction, reflecting the initial rebar stress state caused by formwork camber and closely agreeing with the stress reversal observed in the experiment, further validating the model’s ability to reflect real-world structural behavior.

The bottom center points of the concrete slab (center span, corresponding to test points HX8, and HY8) were selected as the X and Y direction monitoring points for comparison. The comparison results are shown in Figure 14. In the finite element simulation under the 9.0 kN/m² load, the maximum tensile strain at the X-direction bottom was 16.8 με, while the experimentally measured value was 16.5 με, with a relative error of 1.8%. The maximum tensile strain at the Y-direction bottom was 15.2 με, and the experimentally measured value was 13.85 με, with a relative error of 8.8%, showing good consistency. In the finite element simulation, due to the exclusion of concrete shrinkage and creep effects and defects in the on-site pouring process, there was some deviation in the strain simulation values at the edges of the bottom slab. However, the overall strain distribution trend still closely matched the experimental data.

In conclusion, the general trend of the finite element simulation closely aligns with the experimental results. However, some discrepancies remain, mainly due to the following six factors: (1) The mechanical properties of the actual materials exhibit variability, and the measured average or standard values of the materials used in the experiments may differ from the actual strength of the test specimens used in the finite element simulation. (2) Limitations of numerical methods and solution accuracy. (3) The finite element model does not account for compression between elements, resulting in deviations in deformation behavior. (4) The embedded element technique was used to embed rebar into concrete in the simulation, but the bond-slip relationship between the two materials was not considered. (5) Construction defects and environmental changes cannot be precisely simulated. (6) Measurement and data processing errors, including the accuracy of strain gauges, crack observation instruments, calibration, installation positions, and other factors, directly affect the quality of the obtained data.

5. Conclusions

This study investigates the load-bearing characteristics of box-shaped core mold hollow floor slabs under vertical loading. Through on-site experiments and refined numerical simulations, the bidirectional bending mechanism and failure evolution of the hollow floor slab under vertical loading were systematically revealed. The main conclusions are as follows:

(1) In on-site experimental studies, under vertical staged loading, the box-shaped core mold hollow floor slab did not exhibit visible cracks, and the strain-load curve of the rebar and concrete showed a linear relationship, indicating that the load-bearing deformation is in the elastic stage. The stress distribution exhibited significant dual characteristics of “banded gradient” and “island-shaped loading,” with the center span forming a bidirectional bending core zone and stress concentration at the column capital edge due to stiffness discontinuity. This reflects the load transfer path to the supporting components.

(2) The concrete–rebar coupled finite element model, based on plastic damage constitutive relations, successfully reproduced the “island-shaped radiation” strain distribution of the rebar and the compressive response at the top slab and tensile response at the bottom slab in the experiment. Under a 9.0 kN/m² load, the rebar strain simulation error was ≤6.9%, and the concrete strain error was ≤8.8%, verifying the model’s reliability.

(3) Based on the results of on-site experiments and finite element simulations, the following optimization directions for the hollow floor slab structural design are proposed: To address the issue of “island-shaped loading” concentration around the column capital, rebar mesh can be locally densified, or high-strength concrete can be used to enhance stress diffusion. The center span slab can optimize the core mold spacing based on the stress gradient, reducing material usage while ensuring stiffness. During construction, strict control of formwork camber accuracy is required to prevent initial deformation from affecting the collaboration between rebar and concrete. Optimizing structural details can improve the overall mechanical performance and cost-effectiveness of the floor slab.