Construction method for deformation coordination and comfort control of asymmetrically suspended floor system

Abstract

The application provides a kind of asymmetric suspension body floor system deformation coordination and comfort control construction method, it is related to building technology field;The method comprises the following steps: S10, floor crack prevention measures, the top floor and the bottom floor of the suspension box are taken in the construction phase in the way of post-cast;S20, floor system comfort design and analysis of suspension structure, suspension structure is connected with cantilever box through steel pipe lifting column, suspension structure is connected with core tube structure through floor system I-beam, the comfort degree is ensured to meet the requirements by designing the I-beam of suspension structure;S30, large-span opening beam safety verification, through laboratory full-scale static load test, accurately understand the stress characteristics and safety of large-span opening beam;The beneficial effects of the application are: the application can achieve the realization of coordinated deformation of suspension structure concrete floor and meet the requirements of floor system comfort, ensure the safety, durability and normal use of structure.

Description

Technical Field

[0001] This invention relates to the field of building technology, and more specifically, to a construction method for coordinating deformation and controlling comfort in asymmetric suspended floor slabs. Background Technology

[0002] Asymmetric suspended structures are novel, employing a mega-truss structure system combined with external cuboids, making them a special type of super high-rise project (i.e., irregularly shaped suspended structure system). In an asymmetric suspended system, the floor slab is a crucial component, not only bearing vertical loads but also providing lateral support stiffness, transferring lateral loads, and coordinating the deformation of vertical load-bearing components. During construction and design, the following issues need to be considered regarding floor slab deformation coordination: 1) Clarifying the deformation relationship between the floor slab and the main structure during construction and establishing a numerical model; 2) Using the numerical simulation results of floor slab deformation coordination during construction to guide subsequent construction; 3) Addressing the issue of high stress and cracking in localized areas of the suspended floor slab; 4) Analyzing the synergistic effects of the floor slab, suspended columns, and truss layers.

[0003] For suspended floors, their lightweight nature and unique boundary conditions make the floor slabs tend to be flexible, with natural frequencies closer to those of human activities. Therefore, the daily activities of office workers may cause excessive vertical vibration responses, potentially leading to psychological dissatisfaction and even physiological problems in long-term occupants. To address the comfort issue, attempts have been made to alter the floor slab's natural frequency by changing the beam height. However, this raises the question of what measures can ensure both comfort and functional requirements while also guaranteeing structural safety. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a construction method for coordinating deformation and controlling comfort in asymmetric suspended floor slabs.

[0005] The technical solution adopted by this invention to solve its technical problem is: a construction method for deformation coordination and comfort control of asymmetric suspended floor slabs, the improvement of which is that the method includes the following steps:

[0006] S10. Crack prevention measures for floor slabs: The top and bottom floor slabs of the suspended box are constructed using post-pouring methods during the construction phase.

[0007] S20. Comfort design and analysis of suspended floor structure: The suspended structure is connected to the cantilever box body through steel pipe columns, and the suspended structure is connected to the core tube structure through the I-beams of the floor. By designing the I-beams of the suspended structure, we can ensure that its comfort meets the requirements.

[0008] S30, Safety verification of large-span open beams: Through full-scale static load tests in the laboratory, the stress characteristics and safety of large-span open beams are accurately understood.

[0009] Furthermore, the feature is that, in step S10, the top floor slab and the bottom floor slab of the cantilever truss are cast in post-construction, and the concrete is poured after the temporary support is removed and the constant load is applied; at the same time, in-plane supports or steel plate strips are set, and the in-plane supports are constructed together with the structural components in the suspended box.

[0010] The core tube floor slab connected to the top of the suspended box is cast in place and in-plane bracing is provided.

[0011] Furthermore, in step S10, after the construction of the top floor slab and the bottom floor slab of the suspended box is completed, the results of the stress and elasticity analysis of the floor slab are compared to verify the role of post-pouring in preventing cracking.

[0012] Furthermore, in step S20, when designing the I-beam of the suspended structure, the electromechanical pipelines are passed through the web of the I-beam, and multiple openings are set in the large span beam of the cantilever area.

[0013] Furthermore, in step S20, the floor slab of the suspended structure system is a large-span floor slab system, and the comfort level of the floor slab of the suspended mechanism is checked based on the following conditions:

[0014] The floor beams are hinged at the ends, and the hanging columns are hinged at the top.

[0015] Based on engineering experience and considering the dynamic characteristics of concrete, select an appropriate modulus of elasticity.

[0016] Select the damping ratio;

[0017] Based on effective distribution of live load.

[0018] Furthermore, in step S20, the vibration comfort of the floor slab is evaluated using the following finite element method:

[0019] The pedestrian excitation load is transformed into the excitation load for frequency domain analysis using Fourier transform, as shown in the following formula:

[0020]

[0021] Among them, f step The frequency of human activity is represented by P, where P represents body weight; n represents the order of the Fourier function terms, ranging from 1 to 4 depending on the activity type; α i This represents the dynamic load factor, and its value depends on the type of activity. This represents the phase difference of the i-th harmonic.

[0022] Furthermore, step S30 specifically includes the following steps:

[0023] S301. Perform corresponding finite element numerical simulations on large-span open beams;

[0024] S302. Conduct loading tests on the beam with openings;

[0025] S303, The experimental conclusions are obtained.

[0026] Furthermore, in step S301, a finite element model was established using ABAQUS for numerical analysis.

[0027] Furthermore, in step S303, finite element analysis is performed using ABAQUS to obtain the stress cloud diagram of the large-span open beam.

[0028] Furthermore, step S302 includes displacement measurement and strain measurement. The displacement measurement measures the flexural deformation of the beam under load, while the strain measurement detects the strain state around the opening of the beam.

[0029] The beneficial effects of this invention are as follows: This invention is applicable to pre-construction simulation analysis of large-span, column-free monolithic concrete floor slabs, reducing floor slab cracking through reasonable and minimal temporary support arrangements or the addition of reinforcing ribs. It is also suitable for stress analysis reference of openings in large-span steel beams, optimizing the internal clear height of the floor while ensuring the safety of the openings in the steel beam web, reducing pedestrian resonance, and improving user comfort. Furthermore, it enables suspended concrete floor slabs to achieve coordinated deformation and meet floor comfort requirements, ensuring structural safety, durability, and normal use. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the construction method for coordinating deformation and controlling comfort of an asymmetric suspended floor slab according to the present invention.

[0031] Figure 2 This is a schematic diagram of the crack-resistant measures for the top floor slab of the suspended box in this invention.

[0032] Figure 3 This is a schematic diagram of the anti-crack measures for standard floor slabs in this invention.

[0033] Figure 4 This is a schematic diagram showing the correspondence between the number of walking excitations and the reduction coefficient in this invention.

[0034] Figure 5 This is a schematic diagram of the step vibration mode of wing No. 1 in this invention.

[0035] Figure 6 This is a schematic diagram of the peak acceleration calculation results for wing 1 in this invention.

[0036] Figures 7 to 9 This is a schematic diagram of the experimental loading device in this invention.

[0037] Figure 10This is a schematic diagram of the internal forces of the beam after the actual load is equivalent to a concentrated load in this invention.

[0038] Figure 11 This is a diagram showing the arrangement of displacement measuring points for the components in this invention.

[0039] Figure 12 The overall strain arrangement of the beam in this invention Figure 1 .

[0040] Figure 13 The overall strain arrangement of the beam in this invention Figure 2 .

[0041] Figures 14 to 16 This is a schematic diagram of the displacement field and force-displacement curve of beam No. 4 in this invention.

[0042] Figure 17 This is a diagram showing the arrangement of strain gauges on beam 4 in this invention.

[0043] Figure 18 This is a schematic diagram showing the location of the maximum stress during the test of beam No. 4 in this invention.

[0044] Figure 19 This is a diagram showing the arrangement of strain gauges on beam 1 in this invention.

[0045] Figure 20 This is a schematic diagram showing the location of the maximum stress during the test of beam No. 1 in this invention.

[0046] Figures 21 to 23 This is the stress cloud diagram of beam No. 4 in the finite element analysis of this invention. Detailed Implementation

[0047] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0048] The following will clearly and completely describe the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Furthermore, all connections / linkages involved in the patent do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this invention can be combined interactively without contradicting each other.

[0049] Reference Figure 1As shown, this invention discloses a construction method for coordinated deformation and comfort control of asymmetric suspended floor slabs. Through this method, the suspended concrete floor slabs can achieve coordinated deformation and meet the comfort requirements of the floor slab, ensuring structural safety, durability and normal use.

[0050] Specifically, the method includes the following steps:

[0051] S10. Crack prevention measures for floor slabs: The top and bottom floor slabs of the suspended box are constructed using post-pouring methods during the construction phase.

[0052] The finite element analysis results of the floor slabs show that the top and bottom floor slabs of the suspended box structure are subjected to significant stress. Therefore, during the construction phase, a post-cast method can be adopted, where concrete is poured after the self-weight and some additional dead loads have been applied and the temporary supports have been removed. According to the comparative results in the construction simulation analysis section, adopting the post-cast method can significantly reduce the internal forces of the floor slabs.

[0053] In this embodiment, the anti-cracking measures for the floor slabs include: the top and bottom floor slabs of the cantilever truss are cast-in-place after the temporary supports are removed and the dead load is applied; simultaneously, in-plane bracing or steel strips are installed, with the in-plane bracing constructed together with the structural components in the suspended box; this controls deformation during construction and also improves the in-plane bearing capacity of the floor slab during normal use, reducing the degree of cracking. The core tube floor slab connected to the top of the suspended box is cast-in-place and in-plane bracing is installed. The core tube floor slab connected to the bottom of the cantilever box does not require casting-in-place due to its smaller stress, but in-plane bracing is required where the local shear force is large; for the design of the cast-in-place concrete floor slab, 0.5SDL can be used to replace DL for load combination, meeting the requirements of the code for bearing capacity and crack width without considering the effect of in-plane bracing.

[0054] Combination Figure 2 , Figure 3 As shown, in this embodiment, it includes a core tube and three suspended boxes located on the core tube, which are referred to as wing 1, wing 2 and wing 3 respectively. Figure 2 Crack-resistant measures for the top floor slab of the suspended box structure. Figure 3 For the standard floor slab crack prevention measures, for the standard floor slabs of wings 1 and 2, a post-cast strip is set between the core tube and the suspended box, and an in-plane support / steel plate strip is set in the post-cast strip to transfer the horizontal force during the construction stage. The floor slab reinforcement is increased between the core tube and the suspended floor. For the standard floor slab of wing 3, additional crack-resistant steel bars are set in the stress concentration area around the core tube column.

[0055] In addition, step S10 includes post-cast stress analysis of the concrete floor slab. After the top and bottom floor slabs of the suspended box are constructed, the results of the floor slab stress and elasticity analysis are compared to verify the effect of post-casting in preventing cracking. Through data comparison and analysis, post-casting of the floor slab has a significant effect on reducing floor slab stress and preventing and controlling floor slab cracking.

[0056] S20. Comfort design and analysis of suspended floor structure: The suspended structure is connected to the cantilever box body through steel pipe columns, and the suspended structure is connected to the core tube structure through the I-beams of the floor. By designing the I-beams of the suspended structure, we can ensure that its comfort meets the requirements.

[0057] In this embodiment, the office floor of the suspended structure system is a large-span floor system, as described in step S20. To ensure that its comfort level meets the requirements, the beams of the suspended floor are designed. Firstly, using a larger beam height allows the structure to meet the requirements. However, while using larger secondary beams provides better comfort, it reduces the clear height of the structure. If the height of the electromechanical pipelines is added, the floor height will be significantly reduced. To ensure that the floor achieves high comfort while also meeting the floor height requirements, in this embodiment, when designing the I-beams of the suspended structure, electromechanical pipelines are routed through the web of the I-beams, and multiple openings are provided in the large-span beams of the cantilever area. This structural system has a unique shape; therefore, it is necessary to conduct a comfort analysis and design for the suspended floor with reserved electromechanical openings in the web of the high-section secondary beams to ensure that the project's comfort level meets the requirements.

[0058] The suspended floor system is a large-span floor system, and comfort is a key consideration in the design. During the preliminary design phase, the comfort level of the office area floor system was checked based on the following conditions:

[0059] 1. Floor beams are hinged at the ends, and hanging columns are hinged at the top.

[0060] 2. Based on engineering experience and considering the dynamic characteristics of concrete, a suitable modulus of elasticity is selected; in this embodiment, the modulus of elasticity is 38 GPa.

[0061] 3. Select the damping ratio. In this embodiment, the damping ratio is 0.02.

[0062] 4. The effective distributed live load is 0.55 kPa.

[0063] Vibration comfort of the floor slab was evaluated using the finite element method based on the British CCIP standard (A Design Guide for Footfall Induced Vibration of Structures). This method, proposed by experts from Arup, transforms pedestrian excitation loads into frequency domain excitation loads through Fourier transform, as shown in the following formula:

[0064]

[0065] Among them, f step The frequency of human activity is represented by P, which represents the body weight (70 kg in this embodiment); n represents the order of the Fourier function term, ranging from 1 to 4 depending on the activity type; α i This represents the dynamic load factor, and its value depends on the type of activity. This represents the phase difference of the i-th harmonic.

[0066] In this embodiment, static terms are not considered in the dynamic analysis; for the pedestrian walking excitation, n=4. The frequency range and dynamic load coefficients provided in CCIP are shown in the table below:

[0067]

[0068] Typically, structures require a certain number of walking stimuli to resonate, but real-world structures have limited spans, and the number of steps a pedestrian takes to stimulate the maximum response may not be sufficient. CCIP addresses this by introducing a reduction factor related to the number of walking steps, which is also related to the damping ratio, such as... Figure 4 As shown. Taking a conservative approach, the pedestrian incentive steps in this project are set at 100 steps, at which point the structure has reached a stable state, equivalent to the case without reduction.

[0069] It should also be noted that experimental studies have found that a group of people walking randomly rarely causes severe vibrations to the structure. This is because the phase of each person's pedestrian excitation is different, and the effects caused by each individual cancel each other out, resulting in a small overall dynamic effect. Therefore, random crowd activity only considers the floor vibration caused by a single person. To obtain the most unfavorable response under different pedestrian frequency excitations, a full-frequency domain human-induced vibration analysis was performed in the pedestrian frequency range (CCIP standard 1.0–2.5 Hz) with a frequency sweep interval of 0.02 Hz, thereby obtaining the most unfavorable floor vibration acceleration.

[0070] In this embodiment, the floor slabs of Wing 1 and Wing 2 are similar in form, both suspended by four columns. Wing 1 has a span of 18.4m, which is larger than the 16.1m span of Wing 2. Therefore, Wing 1 is used as the typical representative in the analysis. Wing 3 is suspended by two columns, and is thus analyzed separately.

[0071] Establishment of the finite element model:

[0072] Use beam elements and plate elements to build a finite element model of the structure, such as Figure 5As shown, each node of the beam element has 6 degrees of freedom. The analysis uses a three-dimensional solid space model, assuming infinite rigidity within the floor slab plane. When considering floor vibration comfort, vertical forces dominate, and the vertical mass component cannot be ignored; therefore, floor loads and structural self-weight should be converted into X, Y, and Z-axis masses. To realistically simulate the floor slab boundary conditions, the floor slab model is used as the analysis object during dynamic characteristic and time history analysis. Finally, the activation and passivation functions of the finite element software are used to view and extract the analysis results of the floor slab.

[0073] Eigenvalue analysis offers two methods for determining mode shapes in finite element software: eigenvector analysis and multiple RITZ vector analysis. These two methods are briefly introduced below:

[0074] (1) Eigenvector analysis can determine the mode shapes and frequencies of undamped free vibration of a system. Before performing eigenvalue analysis, the element masses in the model need to be automatically converted into concentrated masses required for dynamic analysis or calculation of static equivalent seismic loads. When only the influence of vertical earthquakes is considered or when analyzing machine vibrations or other vertical vibrations on the floor slab, "convert to Z" may be more appropriate. However, if "convert to X, Y, Z" is selected in this case, a considerable number of mode shapes need to be calculated when using the subspace iteration method or the Lanczos method to ensure the mode shape participation in the Z-axis direction. For complex spatial structural systems, the number of mode shapes may even need to be hundreds, which will increase the computational workload and reduce the computational accuracy.

[0075] (2) RITZ vector analysis seeks to find the mode shapes excited by specific loads. In response spectrum and time history analysis based on the modal superposition method, this method provides a better foundation than the eigenvector method. Rayleigh-Ritz analysis has the effect of reducing the degrees of freedom of the system, and has the characteristics of fast calculation convergence and relatively accurate calculation results. Because it considers the load distribution state and dynamic contribution, it considers more effective mode shapes and obtains a higher mass participation factor. Therefore, it can obtain better results for capturing high-frequency responses to dynamic loads. It is suitable for calculating large-span complex spatial structural systems.

[0076] The simulation of wing number 1 yielded the following main analysis results: Figure 6 As shown (0.046m / s) 2 The analysis results show that the current floor slab design stiffness can meet the comfort requirements. However, it should also be noted that due to the large span, the natural frequency of the floor slab is low. The secondary beams of the floor slab should have a higher cross section, and the electromechanical openings should be reserved in the web. This can provide better comfort for the floor slab and also save on the net floor height.

[0077] S30, Safety verification of large-span open beams: Through full-scale static load tests in the laboratory, the stress characteristics and safety of large-span open beams are accurately understood.

[0078] After openings were made in the long-span beams, the dimensions of these openings did not meet the structural requirements of the "Technical Specification for Steel Structures of High-Rise Civil Buildings" JGJ99-2015. In order to accurately understand the stress characteristics and safety of such beams with openings, a full-scale static load test was conducted in the laboratory.

[0079] Step S30 specifically includes the following steps:

[0080] S301. Finite element numerical simulation of a large-span open beam was performed. To better analyze the stress condition of the open beam, a finite element model was established using ABAQUS 13 for numerical analysis. The material constitutive model used in this analysis was a bilinear constitutive model with a yield strength of 345 MPa, an ultimate strength of 470 MPa, an elastic modulus of 210 GPa, and a Poisson's ratio of 0.3. The finite element loading scheme for the beam was the same as that used in the experiment, with a loading coefficient of 1.5 (i.e., 1.5 times the standard value), resulting in loads of 120 kN, 120 kN, 225 kN, 120 kN, and 120 kN.

[0081] S302. Conduct loading tests on the beam with openings;

[0082] In this embodiment, the design requires a loading test on the open beam, with the beam being full-scale. Pre-fabricated beams No. 1 and No. 4 are selected, and static load tests are conducted under laboratory conditions, based on the structural design load (floor slab self-weight 3KN / m). 2 Raised floor and suspended dead load: 1.3 KN / m 2 and floor live load 3.5KN / m 2 The total design load for the floor is 7.8 kN / m². 2 If the middle span beam is used for test verification (lateral span of 3540mm), the upper linear load on the beam is 27.62KN / m; the test loading device is as follows: Figures 7 to 9 As shown.

[0083] like Figure 10 As shown, the uniformly distributed load can be equivalent to five concentrated loads. A concentrated force of 150 kN is applied at the midpoint of the beam, with two additional loading points of 80 kN each placed 3 m and 6.6 m away from the midpoint. This satisfies the equivalent structural design load of 7.8 kN / m. 2 .

[0084] Three jacks were used for loading during the test. The load was applied in stages, with each stage increasing by 10% of the design load. If the component failed when the load reached 1.3 times the design load, loading was stopped. The loading sequence is shown in the table below.

[0085]

[0086]

[0087] In this embodiment, the experiment used three 100t reaction frames and jacks to achieve concentrated force loading at three points. Data acquisition was performed using a Donghua DH3816N data acquisition instrument and related software. The force values ​​of the jacks, the deformation values ​​of the displacement sensors, and the strain measurement values ​​were connected to the acquisition instrument to achieve synchronous data acquisition. The measurements included both displacement measurement and strain measurement.

[0088] Displacement measurement: In order to measure the flexural deformation of a component under load, displacement measurement points are set up as follows: Figure 11 As shown.

[0089] Strain Measurement: Since the component is an open beam, stress concentration may occur around the opening under vertical loads, leading to component failure. Therefore, this test focuses on the strain change state around the opening of the component. Hence, the strain arrangement of the component is as follows: Figure 12 , Figure 13 As shown, in addition, two strain gauges are arranged on the inner side of the upper flange and three strain gauges are arranged on the outer side of the lower flange to measure the stress of the upper and lower flanges at mid-span.

[0090] S303, The experimental conclusions are obtained.

[0091] In this embodiment, based on the experimental and finite element analysis results, the displacement field and force-displacement curve of beam No. 4 are as follows: Figures 14 to 16 As shown, where Figure 14 The mid-span load is 153.375 kN (1.0 times the design load). Figure 15 The mid-span load is 198.375 kN (1.3 times the design load). Figure 16 The mid-span load is 228.38 kN (1.5 times the design load). The test and finite element analysis results for beam No. 4 are shown in the table below.

[0092]

[0093] Through comparative analysis of finite element and experimental results, the following conclusions were drawn:

[0094] (1) The finite element calculation results are closer to the state of the specimen under external force;

[0095] (2) Beam No. 4 basically maintains linear elastic deformation under 1.3 times the design load;

[0096] (3) The finite element and experimental results of the maximum deflection deformation of beam No. 4 under the design load are 58.78 mm and 57.18 mm, respectively, which is about 0.34% of the span; the finite element and experimental results of the maximum deflection deformation under 1.3 times the design load are 75.29 mm and 77.61 mm, respectively, which is about 0.45% of the span; the finite element result of the maximum deflection deformation under 1.5 times the design load is 89.87 mm, which is about 0.53% of the span.

[0097] The test results for beam 1 are similar to those for beam 4, and will not be described in detail in this embodiment.

[0098] Based on the strain measurement layout scheme described above, the stress measurement points for beam 4 are arranged as follows: Figure 17 As shown. Analysis of the stress test results for beam No. 4 shows that, since the maximum thickness of the steel beam plate is 20mm, according to Section 4.4.1 of the "Code for Design of Steel Structures (GB50017-2017)", the yield strength of the steel is fy = 345MPa. However, the test results indicate that:

[0099] (1) Under the design load, i.e., a mid-span load of 150 kN and a side load of 80 kN, the stress at the mid-span of beam No. 4 is the greatest. The tensile stress on the lower flange is 237.78 MPa, and the compressive stress on the upper flange is 189.97 MPa. The tensile stress at measuring point 27 at the opening is the greatest, at 97.31 MPa, and the compressive stress at measuring point 20 is the greatest, at 59.60 MPa. Therefore, the test on the beam with the opening shows that the maximum stress of the beam under the design load is less than the yield strength of Q345 steel, which is 345 MPa.

[0100] (2) Under a load of 1.3 times the design load, i.e., a mid-span load of 195 kN and side loads of 105 kN, the stress at the mid-span of beam No. 4 is the greatest. The tensile stress on the lower flange is 320.83 MPa, and the compressive stress on the upper flange is 256.71 MPa. The maximum tensile stress (126.46 MPa) is observed at measuring point 27 at the opening, and the maximum compressive stress (85.50 MPa) is observed at measuring point 20. Therefore, the test on the beam with the opening shows that the maximum stress (320.83 MPa) of the beam under a load of 1.3 times the design load is less than the yield strength (345 MPa) of Q345 steel. The location of the maximum stress in the test of beam No. 4 is shown below. Figure 18 As shown.

[0101] The stress measuring points of beam No. 1 are arranged as follows: Figure 19 As shown, since the maximum thickness of the steel beam plate is 20mm, according to Section 4.4.1 of the "Code for Design of Steel Structures (GB50017-2017)", the yield strength of the steel is fy = 345MPa. However, test results show that:

[0102] (1) Under the design load, i.e., a mid-span load of 150 kN and a side load of 80 kN, the stress at the mid-span of beam No. 1 is the greatest. The tensile stress on the lower flange is 220.12 MPa, and the compressive stress on the upper flange is 205.41 MPa. The tensile stress at measuring point 39 at the opening is the greatest, at 113.18 MPa, and the compressive stress at measuring point 38 is the greatest, at 99.47 MPa. Therefore, the test on the beam with the opening shows that the maximum stress of the beam under the design load is less than the yield strength of Q345 steel, which is 345 MPa.

[0103] (2) Under a load of 1.3 times the design load (i.e., a mid-span load of 195 kN and side loads of 105 kN), the stress at the mid-span of beam No. 1 is the highest. The tensile stress on the lower flange is 302.14 MPa, and the compressive stress on the upper flange is 290.47 MPa. The maximum tensile stress (146.32 MPa) is observed at measuring point 39 at the opening, while the maximum compressive stress (134.35 MPa) is observed at measuring point 38. Therefore, the test on the beam with the opening shows that the maximum stress of 302.14 MPa under a load of 1.3 times the design load is less than the yield strength of Q345 steel (345 MPa). The location of the maximum stress in the test of beam No. 1 is shown below. Figure 20 As shown.

[0104] The finite element stress analysis results of the beam are as follows. The stress cloud diagram of this large-span open beam was obtained by performing the finite element analysis using ABAQUS 6.13. Figures 21 to 23 As shown, where Figure 21 The mid-span load is 153.375 kN (1.0 times the design load). Figure 22 The mid-span load is 198.375 kN (1.3 times the design load). Figure 23 The mid-span load is 228.38 kN (1.5 times the design load).

[0105] Finite element analysis shows that:

[0106] (1) Under the design load, i.e., the mid-span load of beam No. 4 is 153.375KN and the load on both sides is 81.8KN, the stress on the upper flange at the mid-span of beam No. 4 is the largest, which is 319.6MPa. Under the design load, the maximum stress of beam No. 4 is less than the yield strength of Q345 steel, which is 345MPa.

[0107] (2) When beam No. 4 is subjected to a load of 1.3 times the design load, that is, when the load at the mid-span of the beam is 198.375KN and the load on both sides is 105.8KN, the stress at the mid-span of the beam is the largest, which is 345.3MPa. The maximum stress of the beam under the load of 1.3 times the design load is slightly greater than the yield strength of Q345 steel, which is 345MPa.

[0108] (3) When beam No. 4 is subjected to a load of 1.5 times the design load, that is, when the load at the mid-span of the beam is 228.38KN and the load on both sides is 126.92KN, the stress at the mid-span of the beam is the largest, which is 345.8MPa. The maximum stress of the beam under the load of 1.5 times the design load is slightly greater than the yield strength of Q345 steel, which is 345MPa.

[0109] Static load tests on large-span beams with openings showed that, under standard loads, the maximum stress was always less than the yield strength of the steel, while the stress at 1.5 times the design load was slightly greater than the yield strength. Therefore, increasing the beam cross-section and adding openings can meet the requirements under normal service conditions.

[0110] Therefore, the present invention provides a construction method for deformation coordination and comfort control of asymmetric suspended floor slabs. By analyzing the deformation coordination of the floor slabs, the use of post-cast floor slabs can optimize the structural stress. The in-plane support / steel strip in the post-cast strip solves the problems of floor slab stress release and cracking. The analysis shows that the floor slab stiffness of the suspended layer generally has little effect on the vertical deformation of the structure. The floor slabs that mainly affect the vertical deformation are the top and bottom floor slabs of the cantilever box. When casting the floor slabs, the truss layer should be cast in place to facilitate stress.

[0111] To address the comfort issues of large-span floor slabs, the design employs a suspended column structure for the upper floor slab, with higher cross-sections for the secondary beams and pre-reserved mechanical and electrical openings in the web. Analysis shows that this structural system meets comfort requirements. To verify the safety of this component during normal use, finite element simulation and laboratory tests were conducted on the large-span open beams, confirming that the openings in the beam cross-section ensure normal structural use. Therefore, the open-section floor slab, while meeting comfort requirements, can guarantee safety under normal operating conditions, and this system can be widely applied to similar engineering projects.

[0112] The present invention provides a construction method for deformation coordination and comfort control of an asymmetric suspended floor slab, which has the following characteristics: (1) MIDAS / GEN is used to simulate and analyze the floor slab construction stage. The calculation model is an overall model. The structural components, support constraints, and load conditions are divided into groups according to the construction steps. The construction stage is defined according to the construction steps and schedule. The program analyzes the control data. (2) After the finite element analysis of the floor slab, it is known that the top and bottom floor slabs of the suspended box are subjected to large forces. In the construction stage, the post-pouring method can be adopted. After the self-weight and some additional dead loads are applied, the temporary supports are removed and then the concrete is poured. The floor slab pouring sequence needs to be optimized. After adopting the post-pouring method, the internal forces of the floor slab can be greatly reduced. (3) In order to ensure that the floor slab can achieve a high level of comfort and that the floor height meets the requirements, a large number of electromechanical pipelines need to pass through the web of the steel beams. In particular, a large number of openings are set in the large span beams in the cantilever area. The structure system has a unique shape. Therefore, the comfort of the suspended floor slab with the electromechanical openings reserved in the web of the high cross section secondary beam is analyzed and designed to ensure that the comfort of the project meets the requirements.

[0113] This invention is applicable to pre-construction simulation analysis of cantilevered floor slabs with significant deformation and vibration, reducing floor slab cracking by adding post-pouring strips, etc. It is also applicable to pre-construction simulation analysis of large-span, column-free monolithic concrete floor slabs, reducing floor slab cracking by reasonably arranging a small number of temporary supports or adding reinforcing bars. Furthermore, it is applicable to stress analysis reference for openings in large-span steel beams, optimizing the internal floor height while ensuring the safety of the steel beam web openings, reducing pedestrian resonance, and improving user comfort.

[0114] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A construction method for coordinating deformation and controlling comfort in asymmetric suspended floor slabs, characterized in that, The method includes the following steps: S10. Crack prevention measures for floor slabs: The top and bottom floor slabs of the suspended box are constructed using post-pouring methods during the construction phase. In step S10, the top and bottom floor slabs of the suspended box are cast in post-construction. After the temporary supports are removed and the dead load is applied, the concrete is poured. At the same time, in-plane supports or steel strips are set, and the in-plane supports are constructed together with the structural components in the suspended box. The core tube floor slab connected to the top of the suspended box is cast in post-construction and in-plane supports are set. In step S10, after the construction of the top floor slab and the bottom floor slab of the suspended box is completed, the results of the stress and elasticity analysis of the floor slab are compared to verify the role of post-pouring in preventing cracking. S20. Comfort design and analysis of suspended floor structure: The suspended structure is connected to the suspended box body through steel pipe columns, and the suspended structure is connected to the core tube structure through the I-beams of the floor. By designing the I-beams of the suspended structure, we can ensure that its comfort meets the requirements. In step S20, when designing the I-beam of the suspended structure, the electromechanical pipelines are passed through the web of the I-beam, and multiple openings are set in the large span beam of the cantilever area. In step S20, the floor slab of the suspended structure system is a large-span floor slab system. The comfort level of the floor slab of the suspended mechanism is checked based on the following conditions: The floor beams are hinged at the ends, and the hanging columns are hinged at the top. Based on engineering experience and considering the dynamic characteristics of concrete, select an appropriate modulus of elasticity. Select the damping ratio; Based on effective live load distribution; In step S20, the vibration comfort of the floor slab is evaluated using the following finite element method: The pedestrian excitation load is transformed into an excitation load for frequency domain analysis using Fourier transform, as shown in the following formula: ； in, Indicates the frequency of human activity. Indicates human body weight; This indicates the term number of the Fourier function, ranging from 1 to 4 depending on the activity type; This represents the dynamic load factor, and its value depends on the type of activity. This represents the phase difference of the i-th harmonic; S30, Safety verification of large-span open beams: Through full-scale static load tests in the laboratory, the stress characteristics and safety of large-span open beams are accurately understood. Step S30 specifically includes the following steps: S301. Perform corresponding finite element numerical simulations on large-span open beams; In step S301, a finite element model was established using ABAQUS for numerical analysis; S302. Conduct a loading test on the beam with the opening; Step S302 includes displacement measurement and strain measurement. Displacement measurement is used to measure the flexural deformation of the beam under load, and strain measurement is used to detect the strain state around the hole of the beam. S303, The experimental conclusions are obtained; In step S303, finite element analysis is performed using ABAQUS to obtain the stress cloud diagram of the long-span open beam.

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