A reinforced prefabricated panel, a method for calculating the ultimate bending stiffness and a method for manufacturing the same

Abstract

The present invention relates to the field of construction, and specifically to a reinforced prefabricated panel, a method for calculating the ultimate bending stiffness, and a method for manufacturing the same. The prefabricated panel includes composite panels arranged in parallel and at intervals in a concrete layer, each composite panel is arranged in the same plane, and the body of the composite panel is parallel to the surface of the prefabricated panel, and the body of the composite panel is provided with reinforced holes distributed in an array. While meeting the design and use requirements of the prefabricated panel, the present invention replaces the steel structure in the traditional reinforced concrete prefabricated panel with the composite panel, thereby reducing the use of concrete materials and increasing the service life of the prefabricated panel.

Description

Technical Field

[0001] The invention relates to the field of construction, and in particular to a reinforced prefabricated board, a calculation method for ultimate bending stiffness and a manufacturing method. Background Art

[0002] At present, conventional concrete precast panels are mainly reinforced concrete thin plate systems, and their manufacturing process is mainly as described in the publication number "CN111216233A": Step 1, installing the mold: placing the bottom template horizontally on the precast site, placing the side template vertically at the edge of the bottom template, using tension screws to fix the bottom template and the side template together, and applying a release agent on the surface of the bottom template and the side template; Step 2, installing steel bars: welding and binding the formed steel bars, and the welding or binding joints are located at places with smaller internal forces; Step 3, pouring concrete: after the concrete is centrally mixed, it is transported to the precast site by a concrete transport vehicle, and concrete is poured vertically and uniformly from top to bottom into the mold. During the pouring process, the position of the steel bars is fixed to ensure that the steel bars do not shift; Step 4: Concrete layer maintenance: after the concrete layer is poured, the concrete layer is vibrated with a concrete layer vibrator; after the surface of the concrete layer is slurried, the surface of the concrete layer is covered with felt, and water is sprinkled for maintenance.

[0003] The design of the formwork system requires that the concrete has a high strength to ensure that the bearing capacity and durability of the precast panels meet the requirements. However, since steel bars need to be set inside the concrete, the concrete is required to form a thicker protective layer to prevent the steel bars from being corroded. The increase in the thickness of the protective layer will affect the amount and cost of concrete materials. At the same time, the reinforced concrete precast panels will have the problem of steel bar corrosion during use, which will reduce the service life of the precast panels, so it is urgent to solve this problem. Summary of the invention

[0004] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides a reinforced prefabricated panel, a method for calculating the ultimate bending stiffness and a manufacturing method. While meeting the design and use requirements of the prefabricated panel, the present invention replaces the steel structure in the traditional reinforced concrete prefabricated panel with a composite material panel, thereby reducing the use of concrete materials and increasing the service life of the prefabricated panel.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A reinforced prefabricated panel comprises composite panels arranged in parallel and at intervals in a concrete layer, each composite panel is arranged in the same plane, and the panel body of the composite panel is parallel to the panel surface of the prefabricated panel, and the panel body of the composite panel is provided with reinforcement holes distributed in an array.

[0007] As a further solution of the present invention: the concrete layer is UHPC concrete, and the composite material board is a glass fiber reinforced composite material board.

[0008] As a further solution of the present invention: the width of the composite material plate is w , 80mm≤ w ≤120mm; the thickness of the composite material plate is h , 3mm≤ h ≤5mm; the spacing between adjacent composite panels in the prefabricated panel is s , 140mm≤ s ≤300mm.

[0009] As a further solution of the present invention: the aperture of the enhancement hole is d , 20mm≤ d ≤40mm; the hole spacing between adjacent reinforcement holes on the composite material plate is c , 60mm≤ c ≤120mm.

[0010] As a further solution of the present invention: the length of the prefabricated board is l 1, 2000mm≤ l 1≤2500mm; the cross-sectional width of the prefabricated panel is b , 900mm≤ b ≤1200mm; the thickness of the prefabricated board is t , 30mm≤ t ≤50mm.

[0011] A method for calculating the ultimate bending stiffness of a reinforced prefabricated panel. The ultimate bending stiffness of the prefabricated panel is :

[0012] ;

[0013] in, b is the cross-sectional width of the precast panel;

[0014] t is the thickness of the precast panel;

[0015] n is the number of arrangements of composite panels in the precast panel;

[0016] w is the width of each composite material plate;

[0017] d is the diameter of the reinforcement holes in the composite material plate.

[0018] As a further solution of the present invention: the aperture of the enhancement hole d for:

[0019] ;

[0020] in, h is the thickness of the composite material plate.

[0021] As a further solution of the present invention: the cross-sectional thickness of the prefabricated board t for:

[0022] ;

[0023] in, l 1 is the length of the precast panel;

[0024] s is the spacing between adjacent composite panels;

[0025] q is the uniformly distributed load on the precast slab.

[0026] As a further solution of the present invention: the hole spacing between adjacent reinforcement holes on the composite material plate c for:

[0027] ;

[0028] in, l 2 is the length of the composite material plate;

[0029] h is the thickness of the composite material plate;

[0030] k is the total number of reinforcement holes on the composite plate.

[0031] A method for manufacturing a reinforced prefabricated panel comprises the following steps:

[0032] S1. Recover the wind turbine blades of the wind turbine generator and disassemble the blades to obtain the shear webs in the blades;

[0033] S2, removing the surface layer of the shear web to obtain the glass fiber reinforced composite material plate laminated in the shear web, and peeling off the laminated glass fiber reinforced composite material plates layer by layer;

[0034] S3, cutting the peeled glass fiber reinforced composite material plate according to the design requirements to obtain a composite material plate of corresponding size, and evenly drilling reinforcement holes on the composite material plate;

[0035] S4. Fix the drilled composite material board in a casting mold, pour UHPC concrete into the mold, and perform curing after pouring.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The present invention adopts glass fiber reinforced composite material plate as reinforcement to replace the steel bars in the traditional reinforced concrete precast plate, so that the concrete does not need to form an excessively thick protective layer, reduces the material consumption of concrete materials, and increases the service life of the precast plate; by drilling holes in the composite material plate, the bonding force between the composite material plate and the ultra-high performance concrete is enhanced, so that the two can work better together, thereby improving the overall bearing capacity and mechanical properties of the plate.

[0038] 2. The present invention manufactures prefabricated panels by recycling glass fiber reinforced composite panels from wind turbine blades, thereby effectively utilizing the waste of retired wind turbine blades, promoting the resource utilization of solid waste, enhancing the bearing capacity and durability of the template, and promoting the recycling and reuse of resources.

[0039] 3. The present invention calculates and predicts the ultimate bending stiffness of the prefabricated panels by constructing an ultimate bending stiffness calculation formula. According to the bending stiffness requirement of subsequent projects, the size of the prefabricated panels can be dynamically adjusted to meet the needs of actual projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of the present invention.

[0041] Figure 2 This is the deformation cloud diagram under the out-of-plane load of the present invention.

[0042] In the figure: 1, concrete layer; 2, composite material plate; 21, reinforcement hole. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] See also Figures 1 - 2 In an embodiment of the present invention, a reinforced prefabricated panel includes a concrete layer 1 and a composite material panel 2 located in the concrete layer 1. The length of the prefabricated panel is l 1, 2000mm≤ l 1≤2500mm; the cross-sectional width of the prefabricated panel is b , 900mm≤ b ≤1200mm; the thickness of the prefabricated board is t , 30mm≤ t≤50mm. The composite material plate 2 is a glass fiber reinforced composite material plate recovered from the blades of a wind turbine generator, and the concrete poured in the concrete layer 1 is UHPC concrete.

[0045] The width of the composite material plate 2 is w , 80mm≤ w ≤120mm; the thickness of the composite material plate 2 is h , 3mm≤ h ≤5mm; the spacing between adjacent composite panels 2 in the prefabricated panel is s , 140mm≤ s ≤300mm.

[0046] The composite panels 2 are arranged side by side in the same plane, and the composite panels 2 are arranged parallel to the prefabricated panel surface. The composite panels 2 are preferably arranged in the middle of the concrete layer 1. The composite panels 2 are provided with reinforcement holes 21 evenly arranged in a rectangular array. The aperture of the reinforcement holes 21 is d , 20mm≤ d ≤40mm; the hole spacing between adjacent reinforcement holes 21 on the composite material plate 2 is c , 60mm≤ c ≤120mm.

[0047] The following steps are involved in manufacturing prefabricated panels:

[0048] S1. Recover the wind turbine blades of the wind turbine generator and disassemble the blades to obtain the shear webs in the blades;

[0049] S2, removing the surface layer of the shear web to obtain the glass fiber reinforced composite material plate laminated in the shear web, and peeling off the laminated glass fiber reinforced composite material plates layer by layer;

[0050] S3, cutting the peeled glass fiber reinforced composite material plate according to design requirements to obtain a composite material plate 2 of corresponding size, and evenly drilling reinforcement holes 21 on the composite material plate 2;

[0051] S4, fixing the drilled composite material plate 2 in a casting mold, pouring UHPC concrete into the mold, and performing curing after the pouring is completed.

[0052] The ultimate bending stiffness of the precast panel is calculated by the following formula:

[0053] ;

[0054] in, b is the cross-sectional width of the precast panel;

[0055] t is the thickness of the precast panel;

[0056] n is the number of arrangements of the composite panels 2 in the prefabricated panel;

[0057] w is the width of each composite material plate 2;

[0058] d is the aperture of the reinforcement hole 21 of the composite material plate 2;

[0059] ;

[0060] in, h is the thickness of the composite material plate 2;

[0061] ;

[0062] in, l 1 is the length of the precast panel;

[0063] s is the spacing between adjacent composite panels 2;

[0064] q is the uniformly distributed load of the precast slab;

[0065] The hole spacing between adjacent reinforcement holes 21 on the composite material plate 2 c for:

[0066] ;

[0067] in, l 2 is the length of the composite material plate 2;

[0068] h is the thickness of the composite material plate 2;

[0069] k is the total number of reinforcement holes on the composite material plate 2.

[0070] Since the size of the diameter of the reinforcement hole 21 on the composite material plate 2 will affect the anchoring performance between the composite material plate 2 and the concrete layer 1, when the diameter of the reinforcement hole 21 is small and the anchoring performance is low, relative slip may occur between the composite material plate 2 and the concrete layer 1, and the cooperative working ability is low, further reducing the bending stiffness of the precast plate. When the diameter of the reinforcement hole 21 is large, it may cause stress concentration. When subjected to force, the stress around the reinforcement hole 21 will increase significantly, further affecting the bending performance of the entire precast plate, causing the precast plate to show greater deformation under a lower load, which is equivalent to a reduction in bending stiffness. Therefore, it is necessary to calculate the optimal diameter of the reinforcement hole 21. dWhen the composite material plate 2 replaces the longitudinal force-bearing steel bars of the conventional reinforced concrete precast plate, it is necessary to meet the minimum reinforcement ratio condition of 0.2%. The optimal hole diameter of the reinforcement hole 21 is calculated based on the minimum reinforcement ratio of 0.2%. d .

[0071] ;

[0072] in, ρ It indicates the reinforcement ratio;

[0073] A f represents the total reinforcement area of ​​the composite material plate 2;

[0074] The thickness of the precast panel t It is also closely related to the bending stiffness. When the thickness of the precast panel t As the thickness of the precast plate increases, its moment of inertia will also increase significantly. Since the bending stiffness is proportional to the moment of inertia, t With the increase of the bending stiffness, the bending stiffness will also be increased. Combined with the empirical parameters, the optimal thickness of the precast plate is calculated under the condition that the bending normal stress of the precast plate does not exceed the design limit. t ;

[0075] ;

[0076] After substituting the corresponding parameters into the above formula:

[0077] ;

[0078] in, σ represents the bending normal stress;

[0079] M is the maximum bending moment at the mid-span of the precast slab;

[0080] W is the section modulus of the precast panel;

[0081] Considering the material cost and construction aspects, thinner prefabricated panels can save materials and reduce the weight of the template, making the template more convenient during transportation and reducing transportation costs. Select the lowest thickness that meets the design conditions t As the best thickness for precast panels.

[0082] Since the cooperation between the composite material plate 2 and the concrete layer 1 is based on the pinning effect between the concrete layer and the openings of the composite material 2, when there are too few holes in the reinforcement holes 21, the pinning effect is too small and good cooperation cannot be achieved. When there are too many holes in the reinforcement holes 21, the composite material reserved between the holes is too thin and prone to shear failure, and good cooperation cannot be achieved. According to empirical analysis, under equilibrium conditions, the hole spacing between adjacent reinforcement holes 21 on the composite material plate 2 is c The length of the composite material plate 2 l 2 satisfies the following relationship:

[0083] ;

[0084] After transformation, the equation is:

[0085] ;

[0086] ;

[0087] The optimal aperture of the enhanced hole 21 is obtained d、 Optimal thickness of precast panels t and the optimal hole spacing between adjacent enhancement holes 21 c After that, the ultimate bending stiffness of the precast panel is calculated.

[0088] When the precast panel is not cracked, the concrete provides the corresponding bending stiffness, which is EI ,in E is the elastic modulus of concrete, I is the section moment of inertia;

[0089] Rectangular cross section I = bt 3 / 12; the elastic modulus of UHPC concrete is a fixed value, which is 30000. Therefore, when it is not cracked, the bending stiffness of the precast panel is 30000. bt 3 / 12. In the ultimate cracking state, the concrete in the tensile zone of the section stops working, and the internal force on the tensile side of the section is provided by the composite material plate 2. The equivalent moment of inertia of the section at cracking is related to the reinforcement ratio. In the ultimate state of cracking, the ultimate bending stiffness of the precast plate is = EI × f ( ρ f ); f ( ρ f ) is the related function.

[0090] In determining the aperture of the enhancement hole 21 d、 Thickness of precast panels tand the hole spacing between adjacent enhancement holes 21 c In the case of b , the number of arrangements of composite panels 2 in prefabricated panels n and the width of the composite material plate 2 w Taking as variable, precast panels of different sizes are designed, and their ultimate bending stiffness under cracking conditions is measured;

[0091] Substitute the relevant data into = EI × f ( ρ f ) formula to fit and get the related function f ( ρ f ) and substitute it into the relevant function f ( ρ f ) The ultimate bending stiffness of the precast panel is finally confirmed to be:

[0092] .

[0093] The numerical model of the precast panel was established using the nonlinear finite element software ABAQUS. A simplified two-dimensional model was established. The UHPC concrete was established using a two-dimensional plane stress unit, and the composite material plate 2 was established using a two-dimensional truss unit. The elastic modulus of the composite material plate 2 is 40 GPa, the elastic modulus of the UHPC concrete is 30 GPa, the width of the precast panel is maintained at 1000 mm, the length is maintained at 2000 mm, and the load is a uniformly distributed load.

[0094] At different sizes, the ultimate bending stiffness of the precast panels obtained by numerical model simulation and the ultimate bending stiffness of the precast panels calculated by the present invention are shown in Table 1 below.

[0095] Table 1

[0096] ;

[0097] In Table 1, b is the cross-sectional width of the precast panel (unit: mm), t is the thickness of the precast panel (unit: mm); n is the number of arrangements of the composite panels 2 in the prefabricated panel; w is the width of the composite material plate 2 (unit: mm); d is the diameter of the reinforcing hole 21 (unit: mm); EI cr is the ultimate bending stiffness of the precast panel calculated by finite element method; EI cr1The ultimate bending stiffness of the prefabricated board calculated by the present invention is shown in Figure 1. It can be seen that the calculation of the present invention has a high accuracy and can better predict the ultimate bending stiffness of the prefabricated board.

[0098] like Figure 2 As shown, it is a deformation cloud diagram of the prefabricated board of the present invention under the out-of-plane load. It can be seen that the high and low gradient of the deformation of the prefabricated board is relatively continuous, and the layering is clear, indicating that the prefabricated board is reasonably stressed, has good collaborative working ability, and has excellent overall performance.

[0099] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

Claims

1. A method for calculating the ultimate bending stiffness of a reinforced prefabricated panel, characterized in that: The prefabricated panel comprises composite panels (2) arranged in parallel and at intervals in a concrete layer (1), each composite panel (2) being arranged in the same plane, and the body of the composite panel (2) is parallel to the surface of the prefabricated panel, and the body of the composite panel (2) is provided with reinforcement holes (21) distributed in an array. The concrete layer (1) is UHPC concrete, and the composite material plate (2) is a glass fiber reinforced composite material plate; the width of the composite material plate (2) is w , 80mm≤ w ≤120mm; the thickness of the composite material plate (2) is h , 3mm≤ h ≤5mm; The spacing between adjacent composite panels (2) in the prefabricated panel is s , 140mm≤ s ≤300mm; The diameter of the enhancement hole (21) is d , 20mm≤ d ≤40mm; the hole spacing between adjacent reinforcement holes (21) on the composite material plate (2) is c , 60mm≤ c ≤120mm; The length of the precast panel is l 1, 2000mm≤ l 1≤2500mm; the cross-sectional width of the prefabricated panel is b , 900mm≤ b ≤1200mm; the thickness of the prefabricated board is t , 30mm≤ t ≤50mm; The ultimate bending stiffness of the precast panel is : ； in, b is the cross-sectional width of the precast panel; t is the thickness of the precast panel; n is the number of arrangements of the composite panels (2) in the prefabricated panel; w is the width of each composite material plate (2); d is the diameter of the reinforcement hole (21) of the composite material plate (2).

2. The method for calculating the ultimate bending stiffness of a reinforced prefabricated panel according to claim 1, characterized in that: The diameter of the enhancement hole (21) d for: in, h is the thickness of the composite material plate (2).

3. The method for calculating the ultimate bending stiffness of a reinforced prefabricated panel according to claim 1, characterized in that: Thickness of precast panels t for: in, l 1 is the length of the precast panel; s is the distance between adjacent composite material plates (2); q is the uniformly distributed load on the precast slab.

4. The method for calculating the ultimate bending stiffness of a reinforced prefabricated panel according to claim 1, characterized in that: Hole spacing between adjacent reinforcement holes (21) on a composite material plate (2) c for: in, l 2 is the length of the composite material plate (2); h is the thickness of the composite material plate (2); k is the total number of reinforcement holes on the composite material plate (2).

5. A method for manufacturing a reinforced prefabricated panel according to any one of claims 1 to 4, characterized in that: The steps include: S1. Recover the wind turbine blades of the wind turbine generator and disassemble the blades to obtain the shear webs in the blades; S2, removing the surface layer of the shear web to obtain the glass fiber reinforced composite material plate laminated in the shear web, and peeling off the laminated glass fiber reinforced composite material plates layer by layer; S3, cutting the peeled glass fiber reinforced composite material plate according to design requirements to obtain a composite material plate (2) of corresponding size, and evenly drilling reinforcement holes (21) on the composite material plate (2); S4, fixing the drilled composite material plate (2) in a casting mold, pouring UHPC concrete into the mold, and performing curing after the pouring is completed.

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