Variable cross-section fabricated concrete beam
By installing tie rods and stirrups at the recesses of prefabricated concrete beams, the problem of easy cracking at the recesses was solved, the tensile and shear strengths were improved, the stability and safety of the structure were achieved, and the construction complexity and cost were reduced.
Patent Information
- Application Number
- CN202520371183.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-05
- Publication Date
- 2026-01-27
- Estimated Expiration
- 2035-03-05
AI Technical Summary
Existing prefabricated concrete beams are prone to cracking at the recesses, affecting the structural performance and safety. Existing solutions have limited effectiveness or increase construction difficulty and cost.
The steel cage, reinforcing components, and precast concrete blocks are used to enhance the tensile and shear strength of the recess by setting tie members and stirrup grids at the recess, including a combination design of multiple reinforcing stirrups and multiple longitudinal bars.
It effectively prevents cracking at the notch, improves the overall structural performance of the variable cross-section precast concrete beam, and is easy to construct and low in cost.
Smart Images
Figure CN223838426U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of building engineering technology, specifically to a variable cross-section prefabricated concrete beam. Background Technology
[0002] In the field of prefabricated buildings, concrete beams, as the main load-bearing components of the structure, have connection methods and performance that are crucial to the stability and safety of the entire structure. Currently, the connection between primary and secondary beams in prefabricated concrete structures is a technical challenge, especially at the notches where primary and secondary beams intersect. Due to the large changes in beam cross-section and stiffness, these notches are prone to cracking.
[0003] Existing prefabricated notched concrete beams have significant design and application flaws. The marked change in beam cross-section at the notch complicates the stress and strain state in this area. Combined with various external forces during transportation and hoisting, this makes the notch highly susceptible to cracking. These cracks not only affect the load-bearing performance of the concrete beam but may also reduce the safety and durability of the entire structure.
[0004] To address these issues, existing technologies have attempted various methods, but none have yielded satisfactory results. For instance, some solutions aim to improve crack resistance by increasing the number of longitudinal reinforcement bars at the notch, but this approach is difficult to implement in practice due to limitations in the arrangement of reinforcement bars at the notch, and its effectiveness is limited. Furthermore, some solutions employ additional supporting structures at the notch to enhance its stiffness, but these solutions often increase construction difficulty and cost, and do not significantly improve the overall performance of the structure. Utility Model Content
[0005] The purpose of this utility model is to provide a variable cross-section precast concrete beam to solve the technical problem that cracking easily occurs at the recess of the variable cross-section precast concrete beam structure in the prior art. The specific technical solution is as follows:
[0006] This utility model provides a variable cross-section precast concrete beam, including a reinforcing cage, a reinforcing component, and a precast concrete block. The precast concrete block has at least one notch. The reinforcing cage includes bottom reinforcement bars and stirrups. The stirrups are fixed to the bottom reinforcement bars and are anchored within the precast concrete block. The reinforcing component includes tie members and a stirrup mesh. The tie members span the notch and are anchored at both ends within the precast concrete block. The stirrup mesh is anchored within the precast concrete block and located below the notch.
[0007] A further improvement of this utility model of variable cross-section precast concrete beam is that the tie member includes a first longitudinal bar, and the first longitudinal bar is included in the first longitudinal bar.
[0008] A further improvement of this utility model of variable cross-section prefabricated concrete beam is that the tie member includes two layers of first longitudinal bars arranged at intervals along the vertical direction, with each layer including at least one first longitudinal bar.
[0009] A further improvement of this utility model of variable cross-section prefabricated concrete beam is that when the number of the first longitudinal reinforcement bars in each layer is two or more, the first longitudinal reinforcement bars are arranged in parallel intervals, horizontal intersections, or vertical intersections.
[0010] A further improvement of this utility model of variable cross-section precast concrete beam is that the tie member includes at least one steel pipe.
[0011] A further improvement of this utility model of variable cross-section precast concrete beam is that the tie member includes at least one steel section.
[0012] A further improvement of this utility model of variable cross-section prefabricated concrete beam is that the stirrup grid includes multiple reinforcing stirrups and multiple second longitudinal bars, with the multiple stirrups wrapped around and fixed to the outer periphery of the multiple second longitudinal bars.
[0013] A further improvement of this utility model of variable cross-section precast concrete beam is that the number of reinforcing stirrups is at least two turns, and the at least two turns of reinforcing stirrups are spaced apart.
[0014] A further improvement of this utility model of variable cross-section precast concrete beam is that the reinforcing stirrup is rectangular, the number of the second longitudinal bars is at least two, and the at least two second longitudinal bars are located at at least two corners of the reinforcing stirrup.
[0015] A further improvement of this utility model of variable cross-section precast concrete beam is that the top of the stirrup is exposed outside the precast concrete block.
[0016] The application of the technical solution of this utility model has the following beneficial effects:
[0017] This utility model relates to a variable cross-section precast concrete beam. By installing reinforcing components at the recessed position, the two sides of the recess are further tied and fixed, thereby improving the tensile and shear strength of the recessed position. This solves the technical problem of cracking easily occurring at the recessed position in existing variable cross-section precast concrete beam structures. The reinforcing components of this utility model can be directly tied and fixed to the reinforcing cage, and can be fabricated using the materials of the reinforcing cage on site. The materials are readily available, the installation is convenient, and the structure is simple.
[0018] In addition to the objectives, features, and advantages described above, this utility model has other objectives, features, and advantages. The present utility model will now be described in further detail with reference to the figures. Attached Figure Description
[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an undue limitation of the present invention. In the drawings:
[0020] Figure 1 This is a longitudinal sectional view of the variable cross-section precast concrete beam of this utility model;
[0021] Figure 2 This is a three-dimensional perspective view of the tie members of the variable cross-section precast concrete beam of this utility model, which are the first longitudinal bars arranged in parallel in one layer.
[0022] Figure 3 This is a longitudinal sectional view of the tie members of the variable cross-section precast concrete beam of this utility model, which are two layers of first longitudinal reinforcement.
[0023] Figure 4 This is a three-dimensional perspective view of the tie members of the variable cross-section precast concrete beam of this utility model, which are the first longitudinal bars arranged in a single layer of crosses.
[0024] Figure 5 This is a three-dimensional perspective view of the tie members of the variable cross-section precast concrete beam of this utility model, which are steel pipes.
[0025] Figure 6 This is a longitudinal sectional view of the connection between the variable cross-section precast concrete beam and the cast-in-place longitudinal reinforcement of this utility model.
[0026] Figure 7 This is a schematic diagram of the stress at the notch of the variable cross-section precast concrete beam of this utility model.
[0027] Among them, 1. notch; 2. stirrup; 3. bottom reinforcement of beam; 4. precast concrete block; 5. tie member; 6. reinforcing component; 7. second longitudinal reinforcement; 8. reinforcing stirrup; 9. cast-in-place longitudinal reinforcement. Detailed Implementation
[0028] The embodiments of this utility model will be described in detail below with reference to the accompanying drawings.
[0029] See Figures 1 to 7 As shown, a variable cross-section precast concrete beam includes a reinforcing cage, a reinforcing component 6, and a precast concrete block 4. The precast concrete block 4 has at least one notch 1. The reinforcing cage includes bottom reinforcement bars 3 and stirrups 2. The stirrups 2 are fixed to the bottom reinforcement bars 3. The bottom reinforcement bars 3 and the stirrups 2 are anchored in the precast concrete block 4. The reinforcing component 6 includes a tie bar 5 and a stirrup mesh. The tie bar 5 spans across the notch 1 and is anchored at both ends in the precast concrete block 4. The stirrup mesh is anchored in the precast concrete block 4 and located below the notch 1.
[0030] Specifically, the tie member 5 can be made of reinforcing bars, steel pipes, or structural steel. Because the tie member 5 spans across the notch 1, this invention is not suitable for lap joints of ordinary secondary beams; it is only applicable to secondary beam structures without reinforcing bars at both ends, where connection is achieved through other reinforcing bars and cast-in-place concrete. In this embodiment, the variable cross-section precast concrete beam is a hollow beam. This structure can also be applied to composite beams of any cross-section to improve the shear resistance of the entire beam and prevent cracking at the notch 1.
[0031] Preferred, such as Figure 1 and Figure 2 As shown, the tie member 5 includes a first longitudinal rib, and the first longitudinal rib is included in the first longitudinal rib.
[0032] Preferred, such as Figure 3 As shown, the tie member 5 includes two layers of first longitudinal ribs spaced apart along the vertical direction, with each layer including at least one first longitudinal rib.
[0033] Preferred, such as Figure 4 As shown, when there are two or more first longitudinal bars in each layer, the first longitudinal bars are arranged in parallel intervals, horizontal intersections, or vertical intersections.
[0034] Preferred, such as Figure 5 As shown, the tie member 5 includes at least one steel pipe.
[0035] Preferably, the tie member 5 includes at least one steel section. The steel section can be of various types, such as angle steel or channel steel, as needed.
[0036] Preferably, the stirrup space frame includes multiple reinforcing stirrups 8 and multiple second longitudinal bars 7, with the multiple stirrups 8 wrapped around and fixed to the outer periphery of the multiple second longitudinal bars 7. This stirrup space frame can further enhance the tensile strength below the notch 1, thereby increasing the probability of cracking at the bottom of the notch 1. Optionally, the second longitudinal bars 7 can also be replaced with hanger bars, thereby increasing the tensile strength below the notch 1.
[0037] Preferably, the number of reinforcing stirrups 8 is at least two turns, and the at least two turns of reinforcing stirrups 8 are spaced apart. In this embodiment, the number of reinforcing stirrups 8 is three, and the specific number can be determined by combining the size of the notch 1 and the size of the beam.
[0038] Preferably, the reinforcing stirrup 8 is rectangular, and there are at least two second longitudinal ribs 7, with at least two second longitudinal ribs 7 located at at least two corners of the reinforcing stirrup 8. Alternatively, second longitudinal ribs 7 can be placed between two adjacent longitudinal ribs as needed. In this embodiment, there are four second longitudinal ribs 7, located at the four corners of the reinforcing stirrup 8.
[0039] Preferred, such as Figure 7As shown, the top of the stirrup 2 protrudes from the precast concrete block 4, and the cast-in-place longitudinal reinforcement 9 is tied to the exposed part, so as to facilitate the subsequent pouring of cast-in-place concrete and anchor the top of the stirrup 2 inside the cast-in-place concrete.
[0040] The reinforcement area A' of tie member 5 at the variable cross section s It needs to be calculated and determined according to the following formula:
[0041]
[0042] In the formula: M is the bending moment at the variable cross section; f' y denoted as , where h is the design value of the compressive strength of tie member 5; h is the height of the composite beam section; a0 is the distance from the centroid of the tensile reinforcement to the tensile edge (the tensile reinforcement is tie member 5); a'0 is the distance from the centroid of the compressive reinforcement to the compressive edge (the compressive reinforcement is the bottom reinforcement 3 of the beam).
[0043] Stress σ of tie member 5 y It should be less than or equal to the design value of tensile strength:
[0044]
[0045] In the formula: f' y A' is the design value for the compressive strength of tie member 5. s A represents the reinforcement area of tie member 5; s f is the reinforcement area of the bottom reinforcement bar 3 of the beam; y This is the design value for the tensile strength of the bottom reinforcement bar 3 of the beam.
[0046] This utility model relates to a variable cross-section precast concrete beam. By installing a reinforcing component 6 at the recess 1, the two sides of the recess 1 are further connected and fixed, thereby improving the tensile and shear strength at the recess 1. This solves the technical problem of cracking easily occurring at the recess 1 in existing variable cross-section precast concrete beam structures. The reinforcing component 6 of this utility model can be directly tied and fixed to the reinforcing cage, and can be fabricated using materials from the on-site reinforcing cage, making it convenient to obtain materials, easy to install, and simple in structure.
[0047] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. A variable cross-section precast concrete beam, characterized in that, The assembly includes a steel cage, a reinforcing component (6), and a precast concrete block (4). The precast concrete block (4) has at least one notch (1). The steel cage includes bottom reinforcement bars (3) and stirrups (2). The stirrups (2) are fixed to the bottom reinforcement bars (3). The bottom reinforcement bars (3) and the stirrups (2) are anchored in the precast concrete block (4). The reinforcing component (6) includes a tie bar (5) and a stirrup mesh. The tie bar (5) spans across the notch (1) and is anchored at both ends in the precast concrete block (4). The stirrup mesh is anchored in the precast concrete block (4) and located below the notch (1).
2. The variable cross-section precast concrete beam according to claim 1, characterized in that, The tie member (5) includes a first longitudinal rib, and the first longitudinal rib is included in the first longitudinal rib.
3. The variable cross-section precast concrete beam according to claim 1, characterized in that, The tie member (5) includes two layers of first longitudinal bars spaced apart along the vertical direction, with each layer including at least one first longitudinal bar.
4. The variable cross-section precast concrete beam according to claim 2, characterized in that, When there are two or more first longitudinal ribs in each layer, the first longitudinal ribs are arranged in parallel intervals, horizontal intersections, or vertical intersections.
5. The variable cross-section precast concrete beam according to claim 1, characterized in that, The tie member (5) includes at least one steel pipe.
6. The variable cross-section precast concrete beam according to claim 1, characterized in that, The tie member (5) includes at least one steel section.
7. The variable cross-section precast concrete beam according to claim 1, characterized in that, The stirrup grid includes multiple reinforcing stirrups (8) and multiple second longitudinal bars (7), with the multiple stirrups (2) wrapped around and fixed to the outer periphery of the multiple second longitudinal bars (7).
8. The variable cross-section precast concrete beam according to claim 7, characterized in that, The number of the reinforcing stirrups (8) is at least two turns, and the at least two turns of the reinforcing stirrups (8) are spaced apart.
9. The variable cross-section precast concrete beam according to claim 7, characterized in that, The reinforcing stirrup (8) is rectangular, and the number of the second longitudinal bars (7) is at least two, with at least two second longitudinal bars (7) located at at least two corners of the reinforcing stirrup (8).
10. The variable cross-section precast concrete beam according to claim 1, characterized in that, The top of the stirrup (2) protrudes from the precast concrete block (4).