Precast beam steel bar anchoring structure

Abstract

The utility model discloses a precast beam steel bar anchoring structure which comprises a precast beam, the left end and the right end of the precast beam are fixedly connected with first high-strength steel bars, the first high-strength steel bars adopt 90-degree bent anchors twice, the left end and the right end of the precast beam are fixedly connected with second high-strength steel bars, the second high-strength steel bars adopt 90-degree bent anchors once, and the first high-strength steel bars and the second high-strength steel bars adopt 90-degree bent anchors twice. The first high-strength steel bars capable of being bent and anchored by 90 degrees once and the second high-strength steel bars capable of being bent and anchored by 90 degrees twice are arranged at the left end and the right end of the precast beam, the anchoring reliability can be remarkably improved, and dependence on pure bonding anchoring is reduced.

Description

Technical Field

[0001] This utility model relates to the field of building engineering technology, and in particular to a precast beam steel reinforcement anchorage structure. Background Technology

[0002] In reinforced concrete structures, the steel bars can bear the load mainly by the bond and anchorage between the steel bars and the concrete. Therefore, the anchorage of the steel bars is the foundation of the load-bearing capacity of the concrete structure. If the anchorage fails, the structure will lose its load-bearing capacity and thus lead to structural failure. The anchorage of the steel bars refers to the extension of the load-bearing steel bars of beams, slabs, columns and other components into the supports or foundations.

[0003] However, most existing precast beam steel reinforcement anchorage structures are connected to the steel reinforcement at the top of the column by straight anchorage. This structure has insufficient anchorage reliability, weak seismic performance, and relies on pure bond anchorage. After searching, it was found that the technical solution provided by the utility model with application number "CN201980652D" also has the above problems. Utility Model Content

[0004] The purpose of this utility model is to provide a precast beam reinforcement anchorage structure, which solves the problem that most precast beam reinforcement anchorage structures in the prior art are connected to the reinforcement at the top of the column by straight anchorage. This structure has insufficient anchorage reliability, weak seismic performance, and relies on pure bond anchorage.

[0005] To achieve the above objectives, a precast beam reinforcement anchorage structure is provided, comprising: high-strength steel bars I are fixedly connected to both ends of the precast beam, the high-strength steel bars I are anchored by two 90-degree bends, and high-strength steel bars II are fixedly connected to both ends of the precast beam, the high-strength steel bars II are anchored by one 90-degree bend.

[0006] According to the aforementioned precast beam reinforcement anchorage structure, a high-strength steel bar three is fixedly connected between the high-strength steel bar one and the high-strength steel bar two.

[0007] According to the aforementioned precast beam reinforcement anchorage structure, the lower end of the high-strength steel bar three is fixedly connected to a column one.

[0008] According to the aforementioned precast beam reinforcement anchorage structure, a second column is fixedly connected to the right end of the precast beam.

[0009] The above solution has the following advantages: By setting high-strength steel bar I that can be bent and anchored 90 degrees once and high-strength steel bar II that can be bent and anchored 90 degrees twice at both ends of the precast beam, this patent can significantly improve the anchoring reliability and reduce the reliance on pure bond anchoring.

[0010] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0011] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0012] Figure 1 This is an overall schematic diagram of a precast beam steel reinforcement anchorage structure according to the present invention;

[0013] Figure 2 This is a schematic diagram of the precast beam steel reinforcement anchorage structure after installation according to this utility model;

[0014] Figure 3 This is an internal schematic diagram of a precast beam steel reinforcement anchorage structure after installation, according to this utility model.

[0015] Legend:

[0016] 1. Precast beam; 2. High-strength steel bar one; 3. High-strength steel bar two; 4. High-strength steel bar three; 5. Column one; 6. Column two. Detailed Implementation

[0017] This section will describe in detail the specific embodiments of the present utility model. The preferred embodiments of the present utility model are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present utility model, but they should not be construed as limiting the scope of protection of the present utility model.

[0018] Reference Figure 1-3This utility model provides a precast beam reinforcement anchorage structure, comprising: a precast beam 1, with high-strength steel bars 2 fixedly connected to both ends of the precast beam 1. The high-strength steel bars 2 employ double 90-degree bend anchorage. The double 90-degree bend anchorage of the high-strength steel bars within the precast beam reinforcement anchorage structure (i.e., "double-hook anchorage") is a special structural design. Its core purpose is to improve anchorage performance through geometric optimization. The main advantages and technical principles of this design are as follows: the double 90-degree bends form a "U" shape, increasing the contact area between the steel bars and concrete. Mechanical interlocking distributes tensile force, reducing the risk of slippage relying solely on bond. The "locking effect" of the hooks resists repeated slippage under dynamic loads (such as earthquakes and wind vibrations). High-strength steel bars (such as HRB600) require long anchorage lengths in ordinary concrete (up to 40d or more). Double hooks can shorten the anchorage length to 25d-30d through stress dispersion. The hook area undergoes local plastic deformation under stress (especially high-ductility steel bars), absorbing seismic energy and preventing brittle failure in the anchorage zone. In seismic-resistant structures, the straight section length of the hooks must be ≥10d (GB). (50011-2010) Double hooks can satisfy this requirement twice. When there is insufficient space at the beam end or node area, double hooks can compress the anchorage length through "folding" to avoid conflict with adjacent reinforcement. Double hooks allow the tensile force of the reinforcement to be gradually transferred to the concrete through two bending points, reducing stress concentration at the anchorage end. The concrete around the hook is under triaxial compression, improving its splitting resistance. The inner diameter of the hook must be ≥4d (for HRB500 and above reinforcement) to avoid excessive stress at the bend leading to fracture. The straight section of each hook must be ≥5d (non-seismic) or ≥10d (seismic). The concrete cover on the outside of the hook must be ≥3d to prevent spalling. Cracks are a concern. High-strength steel bars must be bent using a cold bending process to avoid the mechanical properties degradation caused by hot bending. After processing, the hooks must undergo magnetic particle testing to detect surface micro-cracks. The concrete strength in the double-hook anchorage zone should not be lower than C40; otherwise, the hooks may crush the concrete. Using HRB600 steel bars for double-hook anchorage, no anchorage failure was observed after 10 years of service in a salt spray environment. In summary, double 90° bent-anchor high-strength steel bars, through geometric strengthening and mechanical optimization, solve the problems of long anchorage, poor seismic resistance, and limited space of high-strength steel bars. They are especially suitable for large-span, seismic, and prefabricated structures. However, their construction requires high precision and must be processed and installed strictly according to specifications.

[0019] High-strength steel bars 2 and 3 are fixedly connected to both ends of the precast beam 1. High-strength steel bars 2 and 3 are anchored by a single 90-degree bend. High-strength steel bars 1 and 2 are fixedly connected by high-strength steel bars 3 and 4. A column 1 and 5 are fixedly connected to the lower end of high-strength steel bars 3 and 4. A column 2 and 6 are fixedly connected to the right end of the precast beam 1. Setting a high-strength steel bar with a single 90-degree bend within the precast beam's steel bar anchorage structure is a design that balances construction convenience and anchorage reliability. It is particularly suitable for applications using high-strength steel bars (such as HRB500 and HRB600). Its core advantages and key technical points are as follows: The 90-degree bend distributes the tensile force of the steel bar through mechanical anchorage, reducing reliance on pure bond anchorage. High-strength steel bars require a longer anchorage length when straight anchored (e.g., approximately 40d for HRB600). The single hook can shorten the length to 25d-30d (adjusted according to concrete strength). The right-angle bend of the hook forms a "mechanical lock," preventing the rebar from being pulled out under dynamic loads (such as earthquakes and wind vibrations). Tests show that the pull-out resistance of single hook anchorage is 20%-40% higher than that of straight anchorage. The tensile force is gradually transferred to the concrete through the straight section of the hook, reducing stress concentration at the anchorage end. High-strength rebar has relatively small surface rib height and lower bond strength with concrete. The hook compensates for this defect through mechanical anchorage. Compared with grouting sleeves or mechanical anchors, single hooks do not require additional accessories, reducing costs by about 10%-15%. The inner diameter of the hook must be ≥4d (HRB500 and above rebar) to avoid excessive stress at the bend leading to fracture. The length of the straight section must be ≥5d in non-earthquake situations (GB). (GB 50010), in seismic applications, the length must be ≥10d (GB 50011), and the concrete cover on the outside of the hook must be ≥3d to prevent local crushing. The concrete strength in the hook anchorage zone should not be lower than C40, otherwise the hook may crush the surrounding concrete (especially high-strength steel bars such as HRB600). For low-strength concrete, spiral stirrups can be configured in the hook zone to enhance restraint. In seismic beams, the hook should face the core area of ​​the component (such as beam-column joints) to avoid exposure and failure of the hook during an earthquake. In summary, single 90° bend anchorage of high-strength steel bars achieves a balance between shortening the anchorage length, improving reliability, and reducing costs through the synergistic effect of mechanical anchorage and bonding. It is especially suitable for seismic fortification, high-strength steel bar applications, and precast beam structures with limited space. During the design, the hook parameters, concrete strength, and construction measures must be strictly controlled to ensure anchorage performance.

[0020] Working principle: High-strength steel bar 12, which can be bent and anchored 90 degrees once, and high-strength steel bar 23, which can be bent and anchored 90 degrees twice, are set on both sides of the precast beam 1. This can significantly improve the reliability of the anchorage with the column and reduce the reliance on pure bond anchorage.

[0021] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

Claims

1. A precast beam reinforcement anchorage structure, comprising: The precast beam (1) is characterized in that high-strength steel bars (2) are fixedly connected to both the left and right ends of the precast beam (1), and the high-strength steel bars (2) are anchored twice at 90 degrees. High-strength steel bars (3) are fixedly connected to both the left and right ends of the precast beam (1), and the high-strength steel bars (3) are anchored once at 90 degrees.

2. The precast beam reinforcement anchorage structure according to claim 1, characterized in that, High-strength steel bar 1 (2) and high-strength steel bar 2 (3) are fixedly connected by high-strength steel bar 3 (4).

3. The precast beam reinforcement anchorage structure according to claim 2, characterized in that, The lower end of the high-strength steel bar three (4) is fixedly connected to column one (5).

4. The precast beam reinforcement anchorage structure according to claim 1, characterized in that, The right end of the precast beam (1) is fixedly connected to column 2 (6).

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