Design and construction method of one-way force prefabricated cast-in-place composite structure

Abstract

This invention relates to a design and construction method for a unidirectional precast cast-in-place composite structure, employing pre-tensioned steel strand formwork-free modules and unreinforced formwork-free modules. The pre-tensioned steel strand formwork-free module comprises ultra-high performance concrete T-shaped components and pre-tensioned steel strands, while the unreinforced formwork-free module is also an ultra-high performance concrete T-shaped component. For horizontally placed unidirectional load-bearing components, multiple pre-tensioned steel strand formwork-free modules are sequentially assembled below the tension zone of the component, followed by the pouring of a first layer of ordinary concrete on top of the pre-tensioned steel strand formwork-free modules. For vertically placed unidirectional load-bearing components, multiple pre-tensioned steel strand formwork-free modules are vertically assembled on the load-bearing side, and multiple unreinforced formwork-free modules are assembled on the back side in the load direction, followed by the pouring of a second layer of ordinary concrete in the center of the cavity. Compared with existing technologies, this invention offers advantages such as improved efficiency and reduced costs throughout the construction process, superior structural performance, outstanding overall economic efficiency, and strong versatility.

Description

Technical Field

[0001] This invention relates to the field of civil engineering, and in particular to a design and construction method for a unidirectional precast cast-in-place composite structure. Background Technology

[0002] Lightweight unidirectional load-bearing structures are widely used in engineering projects such as building floor slabs, bridge beams and columns, culvert covers and side walls or base slabs. They are generally constructed using on-site casting methods, employing bamboo plywood molding, resulting in high carbon emissions and significant on-site pollution. Adopting formwork-free technology, through factory-prefabricated formwork systems, can effectively save resources and avoid on-site waste. Traditional formwork systems struggle to balance strength, stiffness, and crack resistance.

[0003] CN201910686902.8 discloses a pre-tensioned ultra-high performance concrete composite beam and its construction method, including a compression zone at the upper part of the composite beam and a tension zone at the lower part of the composite beam. The tension zone is made of ultra-high performance concrete and has several parallel prestressing tendons arranged internally using the pre-tensioning method; the force direction of each prestressing tendon is parallel to the tensile force direction borne by the tension zone; the compression zone is made of ordinary concrete and is fixed to the tension zone by pre-reserved steel bars set in the tension zone. During construction, the prestressing tendons in the tension zone are tensioned first, and the tension zone is poured with ultra-high performance concrete. After the tension zone reaches its design strength, the compression zone is poured with ordinary concrete on top of the tension zone. However, on-site steel bar tying is still required, making true "reinforcement-free" construction impossible; the tension zone is still a single precast component, preventing modular and flexible splicing. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the existing technology and provide a design and construction method for a unidirectional precast cast-in-place composite structure, which improves efficiency and reduces consumption throughout the construction process, has better structural stress performance, outstanding comprehensive economic benefits, and strong versatility.

[0005] The objective of this invention can be achieved through the following technical solutions: This invention provides a design and construction method for a unidirectional precast cast-in-place composite structure, employing two types of precast modules: pre-tensioned steel strand formwork-free modules and unreinforced formwork-free modules; The pre-tensioned steel strand template-free module includes an ultra-high performance concrete T-shaped component and a pre-tensioned steel strand, and the unreinforced template-free module is an ultra-high performance concrete T-shaped component. For horizontally placed unidirectional load-bearing components used to withstand vertical forces, during construction, multiple pre-tensioned steel strand template-free modules are first spliced ​​and placed below the tension zone of the component, and then the first ordinary concrete is poured on top of the pre-tensioned steel strand template-free modules to form an integral composite structure; below the tension zone is one side of the composite section to be formed.

[0006] For vertically placed unidirectional load-bearing components used to withstand lateral forces, during construction, multiple pre-tensioned steel strand template-free modules are vertically spliced ​​on the load-bearing side, and multiple unreinforced template-free modules are spliced ​​on the back side in the force-bearing direction. Then, a second ordinary concrete is poured in the cavity formed by the pre-tensioned steel strand template-free modules and the unreinforced template-free modules to form an integral composite structure.

[0007] Furthermore, the pre-tensioned steel strand is prestressed according to the process flow of pre-tensioning, casting, equal strength, and release.

[0008] Furthermore, the total height of the cross-section of the horizontally placed components. h The following formulas are used to determine the bearing capacity and crack resistance: ; ; ; In the formula: M u , M s These are the basic bending moment and frequent bending moment borne by the structure during the usage phase, converted to a single module, in N·m; f pd , f p , f t , f c These represent the allowable tensile strength of steel strand, the release stress of steel strand, the allowable tensile strength of ultra-high performance concrete, and the allowable compressive strength of ordinary concrete, respectively, in Pa. h , b , t These are the total structural height, module width, and module thickness, respectively, in meters (m). x Equivalent compression height, in meters (m).

[0009] Furthermore, the total thickness of the cross-section of the vertically placed component. h The calculation method is the same as that for the total cross-sectional height of horizontally placed components, only the formula for calculating the equivalent compressive height x is adjusted as follows: ; In the formula: f u The allowable compressive strength of ultra-high performance concrete is expressed in Pa.

[0010] Furthermore, the standard dimensions of the pre-tensioned steel strand template-free module and the unreinforced template-free module are: width b = 20cm, thickness t = 20cm; they can be adjusted according to the actual component dimensions, with an adjustment range of width -2 to +5cm and thickness -2 to +5cm. The adjustment range is based on the standard dimensions, with increases or decreases.

[0011] Furthermore, the tension stress of the steel strand f p It has a rated strength of 1200MPa; it can be adjusted according to actual stress requirements, with an adjustment range of ±200MPa.

[0012] Furthermore, the splice joints between the pre-tensioned steel strand modules without formwork form an integral load-bearing system after the first ordinary concrete is poured, without the need for additional reinforcing steel bars.

[0013] Furthermore, for horizontally placed unidirectional load-bearing components, the splicing joints of the pre-tensioned steel strand formless modules form an integral load-bearing system with the two types of modules through a second ordinary concrete, without the need for additional load-bearing steel bars.

[0014] Furthermore, for vertically placed unidirectional load-bearing components, the flanges of the ultra-high performance concrete T-shaped component are arranged facing outwards from the component, serving as the panel of the formwork that does not need to be removed, and the web is used to transfer the interface shear force.

[0015] Furthermore, the pre-tensioned steel strands are arranged along the length of the ultra-high performance concrete T-shaped member and are located at the junction of the web and flange of the T-shaped member, with the tensioning direction parallel to the axis of the force direction of the member.

[0016] Compared with the prior art, the present invention has the following advantages: (1) Improved efficiency and reduced consumption throughout the construction process. The prefabricated modules directly serve as permanent, non-removable formwork, eliminating the traditional bamboo plywood or steel formwork erection, dismantling, and cleaning procedures, significantly reducing on-site construction waste, timber consumption, and construction dust pollution; the standard width of a single module is only 20cm, which is lightweight and can be manually handled and spliced ​​without relying on large hoisting equipment, greatly improving on-site assembly efficiency; the entire system does not require on-site binding of reinforcing bars, eliminating the need for reinforcing bar processing and installation, greatly simplifying the process and significantly shortening the construction cycle; the pre-tensioning, pouring, and release of the steel strands are all completed in the factory, avoiding the precision fluctuations of on-site prestressed construction, and making the process quality more controllable.

[0017] (2) Superior structural stress performance. By pre-stressing the steel strands inside the module, the compressive stress can be effectively offset during the service stage, improving the crack resistance of the components and extending the service life of the structure; the ultra-high performance concrete T-shaped component has high stiffness and excellent bonding performance with the post-cast ordinary concrete, and can achieve synergistic stress without the need for additional shear connection components. The bearing capacity of the combined system fully meets the requirements of the specifications; at the same time, simplified bearing capacity and crack resistance verification formulas are given. Only the module size, material strength and design bending moment need to be input to complete the selection. There is no need for complicated finite element analysis, and the project implementation is strong.

[0018] (3) Good overall economic benefits. In terms of cost, it saves many expenses such as formwork procurement / rental, steel bar procurement and binding, and on-site prestressed construction; in terms of indirect costs, the construction period is shortened due to the fast construction speed, reducing on-site management investment, and the components have good crack resistance, resulting in lower maintenance costs in the later stage; in addition, the modules are produced in a standardized factory, the material loss is much lower than on-site processing, no formwork waste is generated, and the resource utilization rate is higher.

[0019] (4) High versatility. It can simultaneously cover two mainstream unidirectional stress scenarios: horizontal bending members (such as building floor slabs, bridge beams, and culvert covers) and vertical load-bearing members (such as culvert side walls, building columns, and retaining walls), making it highly versatile. The module size can be adjusted as needed within the range of -2 to +5cm, and the tension of the steel strands can be flexibly configured within the range of 1000 to 1400MPa, which can adapt to the needs of engineering projects with different spans and different load levels. Attached Figure Description

[0020] Figure 1 This is a 3D schematic diagram of a pre-tensioned steel strand template-free module; Figure 2 This is a 3D schematic diagram of a rib-free, template-free module. Figure 3 A cross-sectional view of a horizontally placed unidirectional load-bearing component; Figure 4 A side view of a horizontally placed unidirectionally stressed component; Figure 5 This is a top view of a vertically placed, unidirectionally stressed component. Figure 6 A side view of a vertically placed unidirectional force-bearing component; Figure 7 A simplified calculation diagram for a horizontally placed unidirectional force-bearing component; Figure 8 A simplified calculation diagram for a vertically placed unidirectional force-bearing component; Figure 9 A simplified diagram of the dimensions of a single module (a horizontally placed unidirectional load-bearing component). Figure 10A simplified diagram of the size layout of a single module (a vertically placed unidirectional force-bearing component).

[0021] Reference numerals: 1. Pre-tensioned steel strand formwork-free module; 11. Ultra-high performance concrete T-shaped component; 12. Pre-tensioned steel strand; 2. Unreinforced formwork-free module; 3. First ordinary concrete; 4. Second ordinary concrete; 5. Vertical force; 6. Lateral force. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0023] Example 1 This embodiment provides a design and construction method for a unidirectional precast cast-in-place composite structure, such as... Figure 1-6 As shown, two types of prefabricated modules are used: pre-tensioned steel strand template-free module 1 and unreinforced template-free module 2; The pre-tensioned steel strand template-free module 1 includes an ultra-high performance concrete T-shaped component 11 and a pre-tensioned steel strand 12, and the unreinforced template-free module 2 is an ultra-high performance concrete T-shaped component. For horizontally placed unidirectional load-bearing components, used to withstand vertical force 5, during construction, multiple pre-tensioned steel strand template-free modules 1 are first spliced ​​and placed below the tension zone of the component, and then the first ordinary concrete 3 is poured on top of the pre-tensioned steel strand template-free modules 1 to form an integral composite structure. For vertically placed unidirectional load-bearing components used to withstand lateral forces 6, during construction, multiple pre-tensioned steel strand template-free modules 1 are vertically spliced ​​on the load-bearing side, and multiple unreinforced template-free modules 2 are spliced ​​on the back side in the force direction. Then, a second ordinary concrete 4 is poured in the cavity formed by the pre-tensioned steel strand template-free modules 1 and the unreinforced template-free modules 2 to form an integral composite structure.

[0024] Example 2 This embodiment provides a design and construction method for a unidirectional precast cast-in-place composite structure, such as... Figure 1-6 As shown, two types of prefabricated modules are used: pre-tensioned steel strand template-free module 1 and unreinforced template-free module 2; The pre-tensioned steel strand template-free module 1 includes an ultra-high performance concrete T-shaped component 11 and a pre-tensioned steel strand 12, and the unreinforced template-free module 2 is an ultra-high performance concrete T-shaped component. For horizontally placed unidirectional load-bearing components, used to withstand vertical force 5, during construction, multiple pre-tensioned steel strand template-free modules 1 are first spliced ​​and placed below the tension zone of the component, and then the first ordinary concrete 3 is poured on top of the pre-tensioned steel strand template-free modules 1 to form an integral composite structure. For vertically placed unidirectional load-bearing components used to withstand lateral forces 6, during construction, multiple pre-tensioned steel strand template-free modules 1 are vertically spliced ​​on the load-bearing side, and multiple unreinforced template-free modules 2 are spliced ​​on the back side in the force direction. Then, a second ordinary concrete 4 is poured in the cavity formed by the pre-tensioned steel strand template-free modules 1 and the unreinforced template-free modules 2 to form an integral composite structure.

[0025] In a specific implementation, the pre-tensioned steel strand 12 is prestressed according to the process flow of pre-tensioning, casting, equal strength, and release.

[0026] like Figure 7 , 9 As shown in the specific embodiment, the total height of the cross-section of the horizontally placed component is... h The following formulas are used to determine the bearing capacity and crack resistance: ; ; ; In the formula: M u , M s These are the basic bending moment and frequent bending moment borne by the structure during the usage phase, converted to a single module, in N·m; f pd , f p , f t , f c These represent the allowable tensile strength of steel strand, the release stress of steel strand, the allowable tensile strength of ultra-high performance concrete, and the allowable compressive strength of ordinary concrete, respectively, in Pa. h , b , t These are the total structural height, module width, and module thickness, respectively, in meters (m). x Equivalent compression height, in meters (m).

[0027] like Figure 8 , 10 As shown, in a specific embodiment, the total thickness of the cross-section of the vertically placed component is... h The calculation method is the same as that for the total cross-sectional height of horizontally placed components, only the formula for calculating the equivalent compressive height x is adjusted as follows: ; In the formula: f u The allowable compressive strength of ultra-high performance concrete is expressed in Pa.

[0028] In a specific implementation, the standard dimensions of the pre-tensioned steel strand template-free module 1 and the unreinforced template-free module 2 are: width b=20cm and thickness t=20cm; they can be adjusted according to the actual component dimensions, with an adjustment range of width -2~+5cm and thickness -2~+5cm.

[0029] In a specific implementation, the tension stress of the steel strand f p It has a rated strength of 1200MPa; it can be adjusted according to actual stress requirements, with an adjustment range of ±200MPa.

[0030] In a specific implementation, the splice joints between the pre-tensioned steel strand template-free modules 1 form an integral load-bearing system after the first ordinary concrete 3 is poured, without the need for additional load-bearing steel bars.

[0031] In a specific implementation, for horizontally placed unidirectional load-bearing components, the splicing joint of the pre-tensioned steel strand template-free module 1 forms an integral load-bearing system with the two types of modules through the second ordinary concrete 4, without additional load-bearing steel bars.

[0032] In a specific implementation, for a vertically placed unidirectional load-bearing member, the flange of the ultra-high performance concrete T-shaped member 11 is arranged facing outward of the member to serve as a panel for a template that does not need to be removed, and the web is used to transfer the interface shear force.

[0033] In a specific embodiment, the pre-tensioned steel strand 12 is arranged along the length of the ultra-high performance concrete T-shaped member 11 and is located at the junction of the web and flange of the T-shaped member, with the tensioning direction parallel to the axis of the force direction of the member.

[0034] (1) For a horizontally placed unidirectional force-bearing member, the controlling internal force under vertical force is: The dimensional parameters and stress control parameters are as follows: The calculated resistance bending moment and crack resistance bending moment are both greater than the control internal force bending moment, indicating that the structural dimensions and the tension stress of the steel strands are reliably controlled.

[0035] (2) For a vertically placed unidirectional force-bearing member, the controlling internal force under horizontal force is: The dimensional parameters and stress control parameters are as follows: The calculated resistance bending moment and crack resistance bending moment are both greater than the control internal force bending moment, indicating that the structural dimensions and the tension stress of the steel strands are reliably controlled.

[0036] Components not described in detail in this embodiment are all existing components that can be purchased through public channels.

[0037] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A design and construction method for a unidirectional precast cast-in-place composite structure, characterized in that, Two types of prefabricated modules are adopted: pre-tensioned steel strand template-free module (1) and unreinforced template-free module (2); The pre-tensioned steel strand template-free module (1) includes an ultra-high performance concrete T-shaped component (11) and a pre-tensioned steel strand (12), and the unreinforced template-free module (2) is an ultra-high performance concrete T-shaped component; For horizontally placed unidirectional force-bearing components, used to bear vertical force (5), during construction, multiple pre-tensioned steel strand template-free modules (1) are first spliced ​​and placed below the tension zone of the component, and then the first ordinary concrete (3) is poured on top of the pre-tensioned steel strand template-free modules (1) to form an overall combined structure; For vertically placed unidirectional load-bearing components used to bear lateral forces (6), during construction, multiple pre-tensioned steel strand template-free modules (1) are vertically spliced ​​on the load-bearing side, and multiple unreinforced template-free modules (2) are spliced ​​on the back side in the force direction. Then, a second ordinary concrete (4) is poured in the middle of the cavity formed by the pre-tensioned steel strand template-free modules (1) and the unreinforced template-free modules (2) to form an integral composite structure.

2. The design and construction method of a unidirectional precast cast-in-place composite structure according to claim 1, characterized in that, The pre-tensioned steel strand (12) is prestressed according to the process flow of pre-tensioning, casting, equal strength, and release.

3. The design and construction method of a unidirectional precast cast-in-place composite structure according to claim 1, characterized in that, Total height of the cross section of horizontally placed components h The following formulas are used to determine the bearing capacity and crack resistance: ； ； ； In the formula: M u , M s These are the basic bending moment and frequent bending moment borne by the structure during the usage phase, converted to a single module, in N·m; f pd , f p , f t , f c These represent the allowable tensile strength of steel strand, the release stress of steel strand, the allowable tensile strength of ultra-high performance concrete, and the allowable compressive strength of ordinary concrete, respectively, in Pa. h , b , t These are the total structural height, module width, and module thickness, respectively, in meters (m). x Equivalent compression height, in meters (m).

4. The design and construction method of a unidirectional precast cast-in-place composite structure according to claim 3, characterized in that, Total thickness of the cross section of vertically placed components h The calculation method is the same as that for the total cross-sectional height of horizontally placed components, only the formula for calculating the equivalent compressive height x is adjusted as follows: ； In the formula: f u The allowable compressive strength of ultra-high performance concrete is expressed in Pa.

5. The design and construction method of a unidirectional precast cast-in-place composite structure according to claim 1, characterized in that, The standard dimensions of the pre-tensioned steel strand template-free module (1) and the unreinforced template-free module (2) are: width b=20cm, thickness t=20cm; they can be adjusted according to the actual component size, with an adjustment range of width -2~+5cm and thickness -2~+5cm.

6. The design and construction method of a unidirectional precast cast-in-place composite structure according to claim 3, characterized in that, Tension stress of steel strand f p It has a rated strength of 1200MPa; it can be adjusted according to actual stress requirements, with an adjustment range of ±200MPa.

7. The design and construction method of a unidirectional precast cast-in-place composite structure according to claim 1, characterized in that, The splice joints between the pre-tensioned steel strand formless modules (1) form an integral load-bearing system after the first ordinary concrete (3) is poured, without the need for additional load-bearing steel bars.

8. The design and construction method of a unidirectional precast cast-in-place composite structure according to claim 1, characterized in that, For horizontally placed unidirectional load-bearing components, the splice joint of the pre-tensioned steel strand formless module (1) forms an integral load-bearing system with the two types of modules through the second ordinary concrete (4), without additional load-bearing steel bars.

9. The design and construction method of a unidirectional precast cast-in-place composite structure according to claim 1, characterized in that, For vertically placed unidirectional load-bearing components, the flanges of the ultra-high performance concrete T-shaped component (11) are arranged facing outwards from the component to serve as the panel of the template that does not need to be removed, and the web is used to transfer the interface shear force.

10. The design and construction method of a unidirectional precast cast-in-place composite structure according to claim 1, characterized in that, The pre-tensioned steel strand (12) is arranged along the length of the ultra-high performance concrete T-shaped member (11) and is located at the junction of the web and flange of the T-shaped member. The tensioning direction is parallel to the axis of the force direction of the member.

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