A reinforcing structure and construction method for reconstructing a stressed member by using a prestressed perforated plate hole
By embedding steel trusses and high-strength fillers into the holes of prestressed porous slabs, combined with fiber composite materials, the problem of reduced structural bearing capacity caused by interruption of prestressing tendons was solved, achieving a comprehensive improvement in structural performance and efficient and economical construction.
Patent Information
- Application Number
- CN202610175208.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-06
- Publication Date
- 2026-05-26
AI Technical Summary
Existing reinforcement technologies cannot effectively restore the prestressed tendon interruption caused by openings in prestressed perforated slabs, resulting in a decrease in structural bearing capacity. Furthermore, traditional methods have drawbacks such as discontinuous force transmission paths, increased structural self-weight, or space occupation.
The reinforcement structure adopts a combination of steel trusses, supports, high-strength fillers and fiber composites. The steel trusses form a continuous load-bearing skeleton in the holes. Combined with the high-strength fillers and fiber composites, the tensile force transmission path of the prestressed tendons is restored. Reliable bonding with the original concrete is achieved by pressure injection of high-strength cement grout.
It achieves precise restoration of the longitudinal bending bearing capacity of prestressed porous slabs, improves the shear resistance of the perforated area, avoids the increase of structural self-weight and the occupation of net height, minimizes the disturbance to the surrounding structure during construction, and is low in cost and has significant effects.
Smart Images
Figure CN122082586A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of building technology, and more specifically to a reinforcement structure and construction method for reconstructing load-bearing components using prestressed perforated plates. Background Technology
[0002] Prestressed hollow core slabs were widely used precast concrete floor slab components in my country from the 1960s to the 1990s. Their main reinforcement typically consisted of 4-5mm diameter, indented, cold-drawn low-carbon steel wire, produced using a pre-tensioning process. These components offered advantages such as light weight, material savings, and high construction efficiency, but also inherent drawbacks including poor overall integrity, weak seismic performance, and limited span. After long-term use, due to environmental erosion, material aging, and differences in early production quality control, problems such as prestressed steel wire corrosion, concrete carbonation, and prestress loss commonly occur, leading to degradation of component stiffness and a decrease in load-bearing capacity.
[0003] In the functional renovation of existing buildings, it is often necessary to create new openings in prestressed porous slabs to add staircases, elevator shafts, pipe shafts, or optimize spatial layout. This operation directly cuts off the prestressing steel wires passing through the opening area, resulting in prestress loss and consequently a decrease in the load-bearing capacity of the components, and the degree of attenuation is difficult to quantify precisely. Furthermore, because the prestressing steel wires themselves have low ductility after tensioning, once cut, the porous slab is prone to insufficient load-bearing capacity, thus requiring appropriate reinforcement treatment.
[0004] Prestressed tendons are key tensile members in hollow core slabs. Their truncation or reduced effectiveness means that the prestressing in that area is completely ineffective or severely insufficient. The slab degenerates from a prestressed member into a regular or deteriorated reinforced concrete member, further weakened by the presence of voids in the cross-section. This deviated from the original design conditions leads to a significant decrease in the flexural capacity, stiffness, and crack resistance of the floor slab in the opening area, resulting in excessive deflection and cracks, creating serious structural safety hazards.
[0005] In masonry structures, issues arise such as the severing of prestressed tendons in prestressed porous slabs due to later modifications involving openings, or the degradation of stiffness and insufficient load-bearing capacity of existing prestressed porous slabs due to long-term use. Current reinforcement techniques mainly include bonding fiber composite materials or steel plates to the bottom of the slab, increasing the cross-section by casting composite layers on the slab surface, and partial demolition and reconstruction. However, these methods have some inherent limitations:
[0006] (1) Defect 1: Discontinuous force transmission path and stress concentration in external reinforcement method
[0007] The commonly used method of reinforcing slabs with carbon fiber cloth or steel plates has a fundamental flaw: it cannot reconstruct the continuous tensile force transmission path of physically severed prestressing tendons. This method uses structural adhesive to bond reinforcing materials to the slab surface, relying on the shear transfer of stress through the adhesive layer to improve the section's bending moment resistance—a form of external compensation. It cannot solve the core problem of prestress loss caused by the interruption of prestressing tendons, nor can it effectively transfer internal forces directly from one end of the slab to the other. For severe stress concentrations and shear-bending combined stress states at the edges of openings, the external material offers limited improvement, and the ends are prone to peeling failure. Its force transmission path inherently has discontinuities and ambiguities, resulting in incomplete reinforcement.
[0008] (2) Defect 2: Increased load and space occupation due to the enlarged cross section method
[0009] The method of reinforcing slabs with a reinforced concrete composite layer on top increases stiffness and load-bearing capacity by increasing the cross-sectional height, but it brings significant side effects. This method permanently increases the structure's self-weight, generating additional loads on the lower load-bearing components and foundation, potentially triggering a chain reaction of secondary reinforcement problems. Simultaneously, it inevitably reduces the building's clear height, affecting its usability. The construction process requires large-scale formwork, rebar tying, and concrete pouring, involving a large amount of wet work, a long curing period, and significant disruption to the building. Furthermore, the quality of the interface between the new and old concrete is a critical weak point; improper handling can easily lead to cracking and delamination, affecting the synergistic performance. This method is a crude reinforcement approach, costly and with obvious negative effects.
[0010] (3) Defect 3: No stress contribution from simple filling treatment
[0011] The practice of simply filling cut-off holes with ordinary concrete or mortar is structurally ineffective. This method merely fills the physical space without providing longitudinal reinforcement, making it unable to withstand the principal tensile stress generated by bending moments. Concrete has extremely low tensile strength, and the unreinforced filler contributes nothing to restoring the slab's bending resistance. This treatment completely ignores the fundamental principles of structural stress, fails to change the fact that this area is a weak point in the structure, and may even introduce greater safety risks by concealing surface defects. Summary of the Invention
[0012] In view of this, this paper proposes a reinforcement structure and construction method for reconstructing load-bearing members using prestressed porous slab holes, aiming to at least partially solve the shortcomings of the existing technology.
[0013] More specifically, according to one aspect of the present invention, a reinforcement structure for reconstructing load-bearing members using prestressed porous plate pores is proposed, comprising:
[0014] The prestressed perforated slab (10) with truncated prestressed tendons, steel truss (20), multiple support members (30), high-strength filler (40) and fiber composite material (50).
[0015] The steel truss (20) includes an upper chord steel bar (21), a lower chord steel bar (22), and a web steel bar (23) that is disposed between the upper chord steel bar and the lower chord steel bar and connects the two; the steel truss (20) is disposed in the opening of the steel truss (20);
[0016] The multiple support members (30) are welded and fixed to the steel truss (20) at intervals along the length direction of the steel truss (20). The support members form multi-point (e.g., three-point) contact constraints with the inner wall of the hole, forcibly keeping the lower chord steel bar located in the vertical lower 1 / 3 height area of the hole section.
[0017] High-strength filler (40) is filled into the holes of prestressed porous plate (10);
[0018] The fiber composite material (50) is horizontally fixed to the bottom of the prestressed perforated plate (10).
[0019] According to an embodiment of the present invention, the steel truss (20) further includes support vertical bars (24) provided at both ends of the upper chord steel bar (21) and the lower chord steel bar (22).
[0020] According to an embodiment of the present invention, the support member (30) is a circumferential positioning steel bar or a transverse support plate.
[0021] According to an embodiment of the present invention, the fiber composite material (50) is carbon fiber cloth.
[0022] According to an embodiment of the present invention, the high-strength filler (40) is high-strength cement, and the 28-day compressive strength of the high-strength cement paste should not be less than 30 MPa.
[0023] According to an embodiment of the present invention, the area As of the lower chord reinforcement of the steel truss (20) is determined based on the following limit state design formula:
[0024] M ≤ α1f c b*x*(h0 - x / 2) + f y 'As'(h0 - as') + f y As(h0 - as)
[0025] Where M is the design value of the bending moment to be borne; α1 is a coefficient; fc is the design value of the axial compressive strength of concrete; b is the equivalent width of the section; x is the height of the concrete compression zone; h0 is the effective height of the section; fy' is the design value of the compressive strength of the steel reinforcement; as is the distance from the longitudinal reinforcement in the tension zone to the tension edge of the section; as' is the distance from the longitudinal reinforcement in the compression zone to the compression edge of the section; fy is the design value of the tensile strength of the steel reinforcement; and As' is the cross-sectional area of the longitudinal reinforcement in the compression zone.
[0026] According to another aspect of the present invention, a construction method for reinforcing a load-bearing member by reconstructing the holes in a prestressed porous plate is provided, comprising:
[0027] Step 1): On-site investigation and structural assessment, including measuring the thickness of the prestressed perforated slab, the diameter of the holes, the span, the location and size of the openings, investigating the distribution of prestressing tendons, and determining the number and location of the cut-off tendons. Assess the existing damage condition of the floor slab, the degree of material degradation, and the load on the superstructure.
[0028] Step 2): Reinforcement design calculations;
[0029] Step 3): Construction preparation and hole pretreatment;
[0030] Step 4): Prefabrication of steel truss and installation of grouting pipe (60), including welding circumferential positioning steel bars along the length of steel truss at the design spacing to ensure that they can restrain the lower chord steel bars to be in the predetermined position, and firmly binding or fixing the grouting pipe to the truss to ensure that its length allows the pipe opening to reach the end of the hole.
[0031] Step 5): Installation and positioning of steel truss. The precast truss is sent into the hole through the construction opening. The support of the circumferential positioning steel bars and the hole wall is adjusted. The spatial position of the truss is precisely adjusted to ensure that the lower chord steel bars are located in the lower 1 / 3 area of the hole throughout the entire process. The truss is fixed to prevent displacement.
[0032] Step 6): Install grouting sealing template: Install sealing template at the construction opening on the slab surface, with grouting nozzles and high-level venting holes reserved in the template;
[0033] Step 7): Prepare grout and pressure injection. Prepare high-strength cement grout according to the ratio. Connect the grouting pipe through the grouting pump and inject the grout into the hole at a pressure of 0.2~0.5MPa. During injection, the grout will start to fill the hole from the bottom. As the grouting proceeds, slowly pull the grouting pipe upwards, keeping the pipe opening always buried below the grout surface.
[0034] Step 8): Monitoring and holding pressure during the infusion process;
[0035] Step 9): Curing and formwork removal;
[0036] Step 10): Repairing openings in the slab surface. Use polymer mortar or fiber-reinforced fine aggregate concrete to repair the construction openings in the slab surface and restore smoothness; and
[0037] Step 11): Bottom treatment and carbon fiber cloth bonding: Grind and clean the corresponding area on the bottom of the prestressed porous plate, apply epoxy resin primer, and bond carbon fiber cloth horizontally.
[0038] According to an embodiment of the present invention, step 2) includes determining the area As of the lower chord reinforcement of the steel truss (20) based on the following limit state design formula:
[0039] M ≤ α1f c b*x*(h0 - x / 2) + f y 'As'(h0 - as') + f y As(h0 - as)
[0040] Where M is the design value of the bending moment to be borne; α1 is a coefficient; fc is the design value of the axial compressive strength of concrete; b is the equivalent width of the section; x is the height of the concrete compression zone; h0 is the effective height of the section; fy' is the design value of the compressive strength of the steel reinforcement; as is the distance from the longitudinal reinforcement in the tension zone to the tension edge of the section; as' is the distance from the longitudinal reinforcement in the compression zone to the compression edge of the section; fy is the design value of the tensile strength of the steel reinforcement; and As' is the cross-sectional area of the longitudinal reinforcement in the compression zone.
[0041] According to an embodiment of the present invention, the construction method further includes:
[0042] Step 12): Quality inspection and acceptance.
[0043] The technical functions and effects of this invention are mainly reflected in the following aspects:
[0044] Precise Restoration of Structural Performance: By directly reconnecting the interrupted tensile force transmission path through the lower chord reinforcement of the truss, the longitudinal bending capacity of the opening area is essentially restored, with a clear effect. Comprehensive Improvement of Stress State: The composite structure formed by the built-in truss and the infill not only provides bending resistance, but its web system also effectively enhances the shear resistance of the opening area and improves stress concentration. Superior Grouting Quality: Using a pressure grouting process with pre-installed grouting pipes that are slowly pulled out from the bottom of the opening, the filling of deep and long openings is absolutely dense, without voids, and the bonding is reliable. Minimal Reinforcement Impact: This is in-situ reinforcement, which does not increase the structural cross-sectional dimensions or self-weight, does not affect the building's clear height, and has strong construction targeting with minimal disturbance to surrounding structures. Universal Material and Process Application: The core filling material can use low-cost, readily available high-strength cement paste or high-performance grouting material, offering strong adaptability. Improved Construction and Economic Efficiency: Standardized processes, prefabricated trusses, concentrated wet work, short construction cycle, and significantly lower overall cost than large-area replacement solutions.
[0045] This invention provides a safe, efficient, economical, and minimally impactful innovative solution for reinforcing and improving the performance of prestressed perforated slabs in masonry structure renovation. Attached Figure Description
[0046] Figure 1 This is a schematic diagram illustrating the application environment of a reinforcement structure that utilizes the holes in a prestressed porous plate to reconstruct a load-bearing member according to an embodiment of the present invention.
[0047] Figure 2 This is a schematic diagram of a reinforcement structure for reconstructing load-bearing members using the holes in a prestressed porous plate according to an embodiment of the present invention;
[0048] Figure 3 A structural schematic diagram of a steel truss for reinforcing structural members by reconstructing load-bearing members using prestressed perforated plate openings, according to an embodiment of the present invention;
[0049] Figure 4 This is a flowchart illustrating a construction method for reinforcing a load-bearing member using prestressed porous plate holes, according to an embodiment of the present invention. Detailed Implementation
[0050] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The content shown is intended to fully illustrate the content of the present invention, but is not intended to limit the present invention.
[0051] Figure 1 This is a schematic diagram illustrating the application environment of a reinforcement structure that utilizes the holes in a prestressed porous plate to reconstruct a load-bearing member according to an embodiment of the present invention. Figure 2 This is a schematic diagram of a reinforcement structure for reconstructing load-bearing members using the holes in a prestressed porous plate according to an embodiment of the present invention; Figure 3 This is a structural diagram of a steel truss for reinforcing structural members by reconstructing the load-bearing components using prestressed perforated plate holes, according to an embodiment of the present invention.
[0052] Referring to the accompanying drawings, the reinforcement structure for reconstructing load-bearing members using prestressed perforated plate holes according to an embodiment of the present invention may include a prestressed perforated plate (10) with truncated prestressed tendons, a steel truss (20), multiple support members (30), a high-strength filler (40), and a fiber composite material (50).
[0053] The steel truss (20) includes top chord reinforcement (21), bottom chord reinforcement (22), web reinforcement (23) placed between and connecting the top and bottom chord reinforcement, and support vertical reinforcement (24) placed at both ends of the top chord reinforcement (21) and bottom chord reinforcement (22). The steel truss (20) is integrally set within the openings of the prestressed perforated slab (10). The built-in steel truss serves as the core load-bearing skeleton, and its form (planar or spatial truss) and member specifications (top chord reinforcement, bottom chord reinforcement, web reinforcement) can be determined based on design load calculations.
[0054] Multiple support members (30), such as circumferential positioning bars or transverse support plates, are tied or welded to the steel truss. These support members form multi-point (e.g., three-point) contact constraints with the inner wall of the hole to ensure the overall spatial position of the truss within the hole, particularly ensuring that the lower chord bars are located in the lower third of the vertical height of the hole to obtain the maximum bending moment arm. The support members also serve as installation tracks and temporary fixing devices before grouting, ensuring that the truss does not twist, sink, or deviate during transportation, installation, and grouting.
[0055] High-strength filler (40) is filled into the holes of the prestressed porous slab (10). The high-strength filler can be high-strength cement grout injected under pressure or a special grout with similar high strength, micro-expansion, and high fluidity properties, filling the entire cut-off hole and the construction opening on the slab surface, firmly bonding the built-in steel truss to the original concrete hole wall, forming a composite core for overall operation. The 28-day compressive strength of the high-strength cement grout should not be less than 30 MPa. Ensure that the steel truss and the original concrete form a non-slip composite load-bearing core.
[0056] The fiber composite material (50) is horizontally fixed to the bottom of the prestressed porous slab (10). Based on the above-mentioned built-in steel truss-grouting composite load-bearing core, a further transverse reinforcement layer is set, that is, the fiber composite material (such as carbon fiber cloth) is horizontally pasted on the bottom of the prestressed porous slab, forming a three-dimensional grid of "longitudinal main reinforcement + transverse distribution reinforcement" with the lower chord of the longitudinal truss, which is used to improve the overall integrity of the slab, suppress crack development and bear local punching shear.
[0057] Figure 4 The following is a flowchart illustrating a construction method for reinforcing a load-bearing member using prestressed porous slab holes, according to an embodiment of the present invention. The construction method of the present invention will be described in detail below with reference to the accompanying drawings.
[0058] As shown in the figure, the construction method includes the following steps:
[0059] 1) On-site investigation and structural assessment: Measure the thickness, hole diameter, span, and opening location and size of the prestressed perforated slab. Investigate the distribution of prestressing tendons and determine the number and location of cut tendons. Assess the existing damage condition of the slab (e.g., cracks, deflection), the degree of material degradation, and the superstructure load.
[0060] 2) Reinforcement Design Calculation: Based on the survey data and load requirements, calculate the design values of bending moment and shear force to be restored after the opening. Design the form and geometry of the built-in steel truss, and calculate and determine the specifications and quantity of the top chord, bottom chord, and web reinforcement. Design the spacing of the circumferential positioning reinforcement. Select high-strength cement grout (requiring a 28-day compressive strength ≥ 30 MPa) or a grout of equivalent performance grade. Design the specifications and bonding range of the carbon fiber cloth on the bottom of the slab. In this step, the core of the design calculation is to determine the area As of the bottom chord reinforcement of the built-in truss, based on the limit state design formula: M ≤ α1f c b*x*(h0 - x / 2) + f y 'As'(h0- as') + f y As(h0 - as). Where M is the design value of the bending moment to be borne; f y As(h0 - as) is the bending moment provided by the newly added bottom chord reinforcement of the truss, and is a critical component. The design must ensure that this moment is sufficient to compensate for the bending capacity lost due to the truss tendon cut-off.
[0061] In the above formula, α1 is a coefficient, calculated according to Article 6.2.6 of the "Standard for Design of Concrete Structures" (GB / T50010-2010) (2024 edition); fc is the design value of the axial compressive strength of concrete; b is the equivalent width of the section; x is the height of the concrete compression zone; h0 is the effective height of the section; fy' is the design value of the compressive strength of the steel reinforcement; as is the distance from the longitudinal reinforcement in the tension zone to the tension edge of the section; as' is the distance from the longitudinal reinforcement in the compression zone to the compression edge of the section; fy is the design value of the tensile strength of the steel reinforcement; As is the cross-sectional area of the longitudinal reinforcement in the tension zone (the area of the lower chord reinforcement of the truss in this invention); and As' is the cross-sectional area of the longitudinal reinforcement in the compression zone.
[0062] 3) Construction Preparation and Hole Pretreatment: Construction openings are made on both ends of the slab surface at the longitudinal ends of the cut-off hole. Thoroughly remove debris and laitance from the hole. Roughen the inner wall of the hole to expose the solid aggregate. After cleaning away dust, apply an epoxy or cement-based interface agent. Roughening creates a rough interface, increasing mechanical bonding. The interface agent (epoxy or cement-based) enhances chemical bonding or blocks pores, improves the performance of the interface transition zone, and prevents the old concrete from absorbing water.
[0063] 4) Prefabrication of steel truss and installation of grouting pipes: Cut and bend the steel bars of each truss member according to the design drawings. Assemble them into a complete planar or spatial truss frame using welding. Weld circumferential positioning steel bars along the length of the truss at the designed spacing to ensure that they can restrain the lower chord steel bars to be in the predetermined position. Securely tie or fix the grouting pipes to the truss, ensuring that their length allows the pipe opening to reach the end of the hole.
[0064] 5) Steel Truss Installation and Positioning: The precast truss is inserted into the opening through the construction opening. The circumferential positioning reinforcement and the support against the opening wall are adjusted, or temporary supports are used, to precisely adjust the spatial position of the truss. The core control is to ensure that the lower chord reinforcement is located in the lower 1 / 3 area of the opening throughout its length. The truss is fixed to prevent displacement.
[0065] Circumferential positioning reinforcement is the core component for achieving precise positioning. It serves both as an installation "track" and forcibly constrains the lower chord reinforcement to be in the optimal tension position. Pre-installed grouting pipes are a key measure to ensure the grouting quality of deep and long holes. Integrated with the truss, they ensure that the grout reaches the deepest part of the hole and achieves complete, dense filling from bottom to top through a slow extraction process.
[0066] 6) Install grouting sealing template: Install a special sealing template at the construction opening on the slab surface. The template is pre-drilled with grouting nozzles and high-level vent holes. A sealing strip is installed between the template and the slab surface and reliably fixed to ensure no grout leakage during pressure grouting.
[0067] 7) Grout Preparation and Pressure Injection: Prepare high-strength cement paste or other high-performance grouting materials according to the specified ratio. Connect the grouting pipe to the grouting pump and inject the grout into the borehole at a pressure of 0.2~0.5MPa. During injection, the grout begins to fill the borehole from the bottom. As grouting progresses, the grouting pipe should be slowly pulled upwards, keeping the pipe opening submerged below the grout surface. The pressure of 0.2~0.5MPa ensures that the highly fluid grout achieves micro-impregnating bonding and effectively eliminates air.
[0068] 8) Monitoring and holding pressure during the grouting process: Observe the grout discharge from the vent. After pure grout is discharged, continue grouting until a steady overflow occurs. Maintain the grouting pressure unchanged and hold it for about 30 seconds to compact the grout and remove air bubbles.
[0069] 9) Curing and Formwork Removal: Keep the grouting area moist for at least 7 days or until it reaches the design strength. After the curing period, remove the sealing formwork and check the surface quality of the grout.
[0070] 10) Repair of openings in the slab surface: Repair the construction openings in the slab surface with polymer mortar or fiber fine stone concrete to restore flatness.
[0071] 11) Bottom treatment and carbon fiber cloth bonding: Grind and clean the corresponding area on the bottom of the board, and apply epoxy resin primer. Bond the carbon fiber cloth horizontally according to the design, ensuring it is flat and free of air bubbles. Apply a protective topcoat.
[0072] 12) Quality Inspection and Acceptance: Check the density of the grout. Verify construction records and material certificates. Conduct on-site load tests if necessary. Compile technical documentation and complete acceptance.
[0073] Compared with existing technologies, this invention has many features and beneficial effects;
[0074] (1) Functional reconstruction of pores and direct substitution mechanism of internal force path
[0075] This invention systematically reconstructs the continuous holes (including newly cut holes and existing holes) of a prestressed porous slab into built-in composite load-bearing components by embedding a customized steel truss and pressure grouting. This truss is deeply embedded within the slab, and its force axis coincides with the original slab's force transmission path. The lower chord reinforcement of the truss is specifically positioned in the tension zone below the hole section, directly replacing the mechanical role of cut-off prestressing tendons or compensating for degraded steel wires, forming a continuous and reliable tensile force transmission path. This characteristic allows the reinforcement measures to simultaneously meet the needs of repairing interruptions and reinforcing deficiencies, fundamentally restoring or improving the integrity of force transmission.
[0076] (2) Integrated composite working mechanism of pressure grouting based on pre-installed grouting pipe
[0077] This invention achieves reliable integral bonding between the built-in steel truss and the existing concrete cavity walls by pre-installing grouting pipes on the steel truss and using pressure grouting of high-strength cement slurry and other cementing materials. Pressure grouting (0.2~0.5MPa) ensures that the grout fills the cavity from the bottom, and the slow withdrawal of the grouting pipe fully fills all voids, penetrating to the interface to form a microscopic wetting bond. This process combines the discrete steel truss with the old concrete into a unified composite load-bearing body, a key technical step in achieving the overall function of the reinforcement system, and is crucial for both types of applications.
[0078] (3) Precise positioning and maximum lever arm guarantee mechanism
[0079] This invention uses circumferential positioning bars tied to the steel truss to ensure that the lower chord steel bars of the truss are precisely and stably positioned in a preset optimal stress location within the openings. This mechanism ensures that the bending moment arm of the reinforcement system always approaches its theoretical maximum value, thereby maximizing the bending contribution efficiency of the lower chord steel bars. It is a universal structural guarantee for achieving precise replacement or reinforcement of the original prestressed tendon path.
[0080] (4) Longitudinal and transverse composite reinforcement and universal minimally invasive technology
[0081] This invention forms a three-dimensional composite system with longitudinally built-in trusses as the main load-bearing element and transverse carbon fiber cloth distribution reinforcement at the bottom of the slab, comprehensively improving the slab's bending, shear, and crack resistance. It employs a minimally invasive construction process using individual holes as units, minimizing damage to the original structure. This process has the same applicability and efficiency for treating holes after truncation and for directly reinforcing holes in existing degraded slabs.
[0082] The above description of the embodiments is intended to enable those skilled in the art to understand and apply the present 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 embodiments described herein, 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 reinforcement structure that utilizes the holes in a prestressed porous plate to reconstruct load-bearing components, characterized in that, include: The prestressed perforated slab (10) with truncated prestressed tendons, steel truss (20), multiple support members (30), high-strength filler (40) and fiber composite material (50). The steel truss (20) includes an upper chord steel bar (21), a lower chord steel bar (22), and a web steel bar (23) that is placed between the upper chord steel bar and the lower chord steel bar and connects the two; the steel truss (20) is placed in the holes of the prestressed perforated slab (10); The multiple support members (30) are welded and fixed to the steel truss (20) at intervals along the length direction of the steel truss (20). The support members form multi-point (e.g., three-point) contact constraints with the inner wall of the hole, forcibly keeping the lower chord steel bar located in the vertical lower 1 / 3 height area of the hole section. High-strength filler (40) is filled into the holes of prestressed porous plate (10); The fiber composite material (50) is horizontally fixed to the bottom of the prestressed perforated plate (10).
2. The reinforcement structure for reconstructing load-bearing components using prestressed porous plate holes as described in claim 1, characterized in that: The steel truss (20) also includes support vertical bars (24) set at both ends of the upper chord bar (21) and the lower chord bar (22).
3. The reinforcement structure for reconstructing load-bearing components using prestressed porous plate holes as described in claim 1, characterized in that: The support member (30) is a circumferential positioning steel bar or a transverse support plate.
4. The reinforcement structure for reconstructing load-bearing components using prestressed porous plate holes as described in claim 1, characterized in that: The fiber composite material (50) is carbon fiber cloth.
5. The reinforcement structure for reconstructing load-bearing members using prestressed porous plate holes as described in claim 1, characterized in that: The high-strength filler (40) is high-strength cement, and the 28-day compressive strength of the high-strength cement paste should not be less than 30 MPa.
6. The reinforcement structure for reconstructing load-bearing members using prestressed porous plate holes as described in claim 1, characterized in that: The area As of the bottom chord reinforcement of the steel truss (20) is determined based on the following limit state design formula: M ≤ α1f c b*x*(h0 - x / 2) + f y 'As'(h0 - as') + f y As(h0 - as) Where M is the design value of the bending moment to be borne; α1 is a coefficient; fc is the design value of the axial compressive strength of concrete; b is the equivalent width of the section; x is the height of the concrete compression zone; h0 is the effective height of the section; fy' is the design value of the compressive strength of the steel reinforcement; as is the distance from the longitudinal reinforcement in the tension zone to the tension edge of the section; as' is the distance from the longitudinal reinforcement in the compression zone to the compression edge of the section; fy is the design value of the tensile strength of the steel reinforcement; and As' is the cross-sectional area of the longitudinal reinforcement in the compression zone.
7. A construction method for a reinforced structure utilizing prestressed porous slab holes to reconstruct load-bearing members according to any one of claims 1-6, characterized in that, include: Step 1): On-site investigation and structural assessment, including measuring the thickness of the prestressed perforated slab, the diameter of the holes, the span, the location and size of the openings, investigating the distribution of prestressing tendons, and determining the number and location of the cut-off tendons. Assess the existing damage condition of the floor slab, the degree of material degradation, and the load on the superstructure. Step 2): Reinforcement design calculations; Step 3): Construction preparation and hole pretreatment; Step 4): Prefabrication of steel truss and installation of grouting pipe (60), including welding circumferential positioning steel bars along the length of steel truss at the design spacing to ensure that they can restrain the lower chord steel bars to be in the predetermined position, and firmly binding or fixing the grouting pipe to the truss to ensure that its length allows the pipe opening to reach the end of the hole. Step 5): Installation and positioning of steel truss. The precast truss is sent into the hole through the construction opening. The support of the circumferential positioning steel bars and the hole wall is adjusted. The spatial position of the truss is precisely adjusted to ensure that the lower chord steel bars are located in the lower 1 / 3 area of the hole throughout the entire process. The truss is fixed to prevent displacement. Step 6): Install grouting sealing template: Install sealing template at the construction opening on the slab surface, with grouting nozzles and high-level venting holes reserved in the template; Step 7): Prepare grout and pressure injection. Prepare high-strength cement grout according to the ratio. Connect the grouting pipe through the grouting pump and inject the grout into the hole at a pressure of 0.2~0.5MPa. During injection, the grout will start to fill the hole from the bottom. As the grouting proceeds, slowly pull the grouting pipe upwards, keeping the pipe opening always buried below the grout surface. Step 8): Monitoring and holding pressure during the infusion process; Step 9): Curing and formwork removal; Step 10): Repair the openings in the slab surface. Use polymer mortar or fiber-reinforced fine aggregate concrete to repair the construction openings in the slab surface and restore flatness. as well as Step 11): Bottom treatment and carbon fiber cloth bonding: Grind and clean the corresponding area on the bottom of the prestressed porous plate, apply epoxy resin primer, and bond carbon fiber cloth horizontally.
8. The construction method according to claim 7, characterized in that, Step 2) includes determining the area As of the lower chord reinforcement of the steel truss (20) based on the following limit state design formula: M ≤ α1f c b*x*(h0 - x / 2) + f y 'As'(h0 - as') + f y As(h0 - as) Where M is the design value of the bending moment to be borne; α1 is a coefficient; fc is the design value of the axial compressive strength of concrete; b is the equivalent width of the section; x is the height of the concrete compression zone; h0 is the effective height of the section; fy' is the design value of the compressive strength of the steel reinforcement; as is the distance from the longitudinal reinforcement in the tension zone to the tension edge of the section; as' is the distance from the longitudinal reinforcement in the compression zone to the compression edge of the section; fy is the design value of the tensile strength of the steel reinforcement; and As' is the cross-sectional area of the longitudinal reinforcement in the compression zone.
9. The construction method according to claim 7, characterized in that, Also includes: Step 12): Quality inspection and acceptance.