A high-performance fabricated concrete beam-column joint with UHPC-X shaped steel bars

Abstract

The utility model belongs to the field of fabricated concrete frame structure discloses a kind of high-performance fabricated concrete beam column joint using UHPC-X shaped steel bar lap joint, the utility model forms half X-shaped bending longitudinal reinforcement structure in beam end prefabrication stage, just need to butt and bind corresponding bending longitudinal reinforcement to beam and column in field, reliable connection can be realized, avoid the complex sleeve, grouting, positioning steel support and other structures in traditional wet connection, greatly reduce field support and positioning process, shorten construction period, improve assembly efficiency. Two groups of bending longitudinal reinforcement in node cross lap form complete X-shaped stress system, longitudinal reinforcement works together with UHPC through intersection area, both can effectively transfer bending moment and shear force, and can enhance the constraint effect of node core area, improve the stress distribution of beam column junction, significantly improve the bearing capacity and ductility of node.

Description

Technical Field

[0001] This utility model belongs to the field of prefabricated concrete frame structures, specifically relating to a high-performance prefabricated concrete beam-column joint using UHPC-X-shaped steel reinforcement lap splicing. Background Technology

[0002] Prefabricated concrete structures offer numerous advantages, including reliable quality, rapid construction, energy efficiency, and environmental friendliness. They are a crucial component of my country's building industrialization and a key direction for future green building development, aligning with the national sustainable development strategy. However, prefabricated concrete frame structures, as an important form within this structural system, often suffer from weak points due to factors such as on-site construction, leading to structural integrity issues and potential collapse. Therefore, reliable prefabricated component connection technology is critical to ensuring the good seismic performance of prefabricated structures.

[0003] Currently, precast beam and column connection technologies in prefabricated structures include dry connections and wet connections. Compared to dry connections, wet connections are widely used due to their advantages such as simpler construction and better structural integrity. A wet connection involves first connecting the reinforcing bars at the ends of the precast beam and column components, and then pouring concrete to achieve the connection. Commonly used wet connection technologies include grout-anchored lap joints and sleeve-grouted connections, but both have certain shortcomings. For example, grout-anchored lap joints are not suitable for reinforcing bars with a diameter greater than 20mm and longitudinal reinforcing bars directly bearing dynamic loads; sleeve-grouted connections have complex structures, high technical requirements, and cannot be effectively inspected for grouting quality. Furthermore, the construction of beam-column wet connections requires numerous temporary supports, and the support construction and assembly / curing processes consume a significant amount of construction time, weakening the advantage of rapid construction in prefabricated concrete frame structures. Therefore, wet connection technology restricts the development of this type of prefabricated structure, and developing a reliable and convenient beam-column wet connection node technology is an urgent problem to be solved for this type of structure.

[0004] With the rapid development of concrete materials towards low carbon and high performance, ultra-high performance concrete (UHPC) is widely used due to its ultra-high strength, high toughness, and high durability. The compressive strength of UHPC is usually above 120 MPa, and its use in wet connection of components has significant technical advantages, such as: (1) UHPC-reinforcement bond strength is high, which can shorten the lap length of the reinforcement to about 1 / 3 to 1 / 2 of that of ordinary concrete; (2) UHPC has rapid early strength development, which can exceed 50 MPa within 24 hours, shortening the curing time of wet connection and enabling rapid construction; (3) UHPC has excellent interface performance with ordinary concrete, reducing the risk of joint cracking. Based on the above performance advantages of UHPC, it is applied to the beam-column connection part of prefabricated concrete frame structure, and combined with rapid assembly technology, green, efficient, and high-performance wet connection technology for prefabricated concrete structure is developed. This can maximize the seismic performance of prefabricated concrete frame structure within a reasonable construction cost, and achieve the goal of structure being equivalent to or even better than cast-in-place, providing a new way to realize the development and application of prefabricated concrete structure. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing wet connection structures, such as complex structure, numerous supports, time-consuming construction, and difficulty in quality control, and to provide a high-performance prefabricated concrete beam-column joint using UHPC-X-shaped steel reinforcement lap splicing.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A high-performance prefabricated concrete beam-column joint using UHPC-X-shaped steel reinforcement lap splicing, the beam-column joint includes a top bent longitudinal bar at the beam end, a bottom bent longitudinal bar at the beam end, a top bent longitudinal bar at the beam end, and a bottom bent longitudinal bar at the beam end. The top and bottom bent longitudinal bars of the beam end overlap at the middle of the beam end to form the first half X-shaped structure. The top and bottom bent longitudinal bars of the beam end are perpendicularly inserted into the column reinforcement cage for fixation. The top and bottom bent longitudinal bars of the beam end are tied with the beam stirrups to form the beam end reinforcement cage. The top and bottom longitudinal bars of the beam are lapped together at the middle of the beam end to form a second half-X-shaped structure. The top and bottom longitudinal bars are perpendicularly inserted into the column reinforcement cage and fixed. The top and bottom longitudinal bars are tied with the beam stirrups to form the beam end reinforcement cage. The first half of the X-shaped structure and the second half of the X-shaped structure are tied together to form an X-shaped steel reinforcement lap joint, and ultra-high performance concrete is poured on the outside of the X-shaped steel reinforcement lap joint.

[0007] A further improvement of this utility model is that one end of the longitudinal reinforcement bent at the top of the beam is bent at an oblique angle to the bottom of the beam, and the other end is bent at a right angle, with the oblique angle bend and the right angle bend being arranged parallel to each other.

[0008] A further improvement of this utility model is that one end of the longitudinal reinforcement bent at the bottom of the beam is bent at an oblique angle to the middle of the beam height, and the other end is bent at a right angle, with the oblique angle bend and the right angle bend arranged parallel to each other.

[0009] A further improvement of this utility model is that one end of the longitudinal reinforcement bent at the top of the beam is bent at an oblique angle to the bottom of the beam, and the other end is bent at a right angle, with the oblique angle bend and the right angle bend arranged parallel to each other.

[0010] A further improvement of this utility model is that one end of the longitudinal reinforcement at the bottom of the beam is bent at an oblique angle to the middle of the beam height, and the other end is bent at a right angle, with the oblique angle bend and the right angle bend arranged parallel to each other.

[0011] A further improvement of this utility model is that the top of the X-shaped steel bar lap splice is provided with additional longitudinal bars at the top of the node, and additional longitudinal bars at the bottom of the node are provided at the bottom of the node.

[0012] A further improvement of this utility model is that the two mating surfaces of the beam-column joint and the beam end are respectively provided with a beam end shear groove key and a beam shear groove key.

[0013] A further improvement of this invention is that the joint between the beam end shear groove key and the beam end, as well as the joint between the beam shear groove key and the beam, are both trapezoidal through sections.

[0014] A further improvement of this invention is that the length of the beam end shear groove key and the beam shear groove key is 1 / 3 of the beam height.

[0015] A further improvement of this invention is that the bending length of the longitudinal reinforcement at the bottom of the beam is half the length of the diagonal.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a semi-X-shaped bent longitudinal reinforcement structure formed during the prefabrication stage at the beam end. This allows for reliable connection between the beam and column on-site simply by butt jointing and binding the corresponding bent longitudinal reinforcement, avoiding the complex sleeves, grouting, and positioning steel supports required in traditional wet connections. This significantly reduces on-site support and positioning procedures, shortens the construction cycle, and improves assembly efficiency. The upper and lower sets of bent longitudinal reinforcement intersect at the joint to form a complete X-shaped load-bearing system. The longitudinal reinforcement works with the UHPC (Ultra-High-Pressure Polymer) through the intersection area, effectively transferring bending moment and shear force while enhancing the constraint effect in the core area of ​​the joint, improving the stress distribution at the beam-column junction, and significantly improving the load-bearing capacity and ductility of the joint. The UHPC of this invention possesses high strength, high density, and excellent interfacial bonding performance. After wrapping the X-shaped lapped reinforcement, it effectively prevents steel corrosion and crack propagation, improving the long-term service performance and fatigue resistance of the joint. Simultaneously, it allows for a thinner joint area, achieving a balance between high performance and lightweight design. The beam and column ends of this invention are standardized precast components with clear geometry in the lap joint area. On-site control is only required for the position of the bent longitudinal reinforcement and the quality of the UHPC pouring, resulting in small construction errors, high forming accuracy, reduced impact of human factors on joint performance, and improved joint consistency and project reliability. The X-shaped lap joint of this invention does not rely on specific connectors and can flexibly adapt to prefabricated beam-column joints with different cross-sectional dimensions and stress levels. It is easy to promote and apply in multi-story frame structures, prefabricated residential buildings, and high-performance structural systems, possessing good engineering feasibility and promotional value. Attached Figure Description

[0017] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a spatial structure diagram of the precast concrete column of this utility model; Figure 3 This is a front view of the precast concrete column of this utility model; Figure 4 This is a three-dimensional view of the precast concrete beam of this utility model; Figure 5 This is a front view of the precast concrete beam of this utility model; Figure 6 This is a top view of the precast concrete beam of this utility model; Figure 7 This is a schematic diagram of the assembly process of this utility model; Figure 8 This is a structural diagram of the internal structure of the post-cast UHPC-X-shaped steel reinforcement lapped beam-column joint of this utility model; Figure 9 This is a detailed drawing of the post-cast UHPC-X-shaped steel reinforcement lapped beam-column joint of this utility model; Figure 10 This is a front view of the post-cast UHPC-X-shaped steel reinforcement lapped beam-column joint of this utility model; Figure 11 This is a top view of the post-cast UHPC-X-shaped steel reinforcement lapped beam-column joint of this utility model; Among them, 1. Precast concrete column; 1-1. Column longitudinal reinforcement; 1-2. Column stirrups; 1-3. Beam stirrups; 1-4. Top bent longitudinal reinforcement at beam end; 1-5. Bottom bent longitudinal reinforcement at beam end; 2. Precast concrete beam; 2-1. Top bent longitudinal reinforcement at beam top; 2-2. Bottom bent longitudinal reinforcement at beam bottom; 3. Beam-column joint; 3-1. Additional longitudinal reinforcement at the top of the joint; 3-2. Additional longitudinal reinforcement at the bottom of the joint; 3-3. Beam end shear groove key; 3-4. Beam shear groove key; 4. Ultra-high performance concrete; 5. Concrete. Detailed Implementation

[0018] To further understand the present invention, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments. It should be understood that the embodiments are merely illustrative and not intended to limit the scope of the invention.

[0019] The UHPC-steel hybrid connection high-performance precast concrete beam-column joint of this embodiment includes a precast concrete column, a precast concrete beam, and a post-cast UHPC-X-shaped steel reinforcement lap beam-column joint.

[0020] See Figure 1 , 2 3. The precast concrete column 1 includes column longitudinal reinforcement 1-1, column stirrups 1-2, beam stirrups 1-3, top bent longitudinal reinforcement 1-4 at the beam end, bottom bent longitudinal reinforcement 1-5 at the beam end, additional longitudinal reinforcement 3-1 at the top of the node, additional longitudinal reinforcement 3-2 at the bottom of the node, and ordinary concrete 5. The column longitudinal reinforcement 1-1 is placed vertically and tied to the column stirrups 1-2 to form a column reinforcement cage; the top bent longitudinal reinforcement 1-4 at the beam end is a steel bar with one end bent at an angle to the bottom of the beam and the other end bent at a right angle, with the angled and right-angled bends parallel to each other; the bottom bent longitudinal reinforcement 1-5 at the beam end is a steel bar with one end bent at an angle to the middle of the beam height and the other end bent at a right angle, with the angled and right-angled bends also parallel to each other. The top bent longitudinal reinforcement 1-4 and the bottom bent longitudinal reinforcement 1-5 at the beam end overlap at the middle of the beam end height to form the first half-X-shaped structure; the two are vertically inserted into the column reinforcement cage and tied for fixation, and then tied with the beam stirrups 1-3 to form the beam end reinforcement cage. After the formwork is erected, a trapezoidal through section beam end shear key 3-3 is set at the joint between the beam end and the node, and then ordinary concrete 5 is poured to form an integral structure.

[0021] See Figure 4 , 5The precast concrete beam 2, as described in sections 6 and 7, comprises a top-bent longitudinal reinforcement 2-1, a bottom-bent longitudinal reinforcement 2-2, beam stirrups 1-3, additional longitudinal reinforcement 3-1 at the top of the joint, additional longitudinal reinforcement 3-2 at the bottom of the joint, and ordinary concrete 5. The top-bent longitudinal reinforcement 2-1 is a steel bar with one end bent at an angle to the bottom of the beam and the other end bent at a right angle, the angled and right-angled sections being parallel. The bottom-bent longitudinal reinforcement 2-2 is a steel bar with one end bent at an angle to the middle of the beam height and the other end bent at a right angle, the angled and right-angled sections also being parallel. The top-bent longitudinal reinforcement 2-1 and the bottom-bent longitudinal reinforcement 2-2 overlap at the middle of the beam height to form a second semi-X-shaped structure, and are vertically inserted into the column reinforcement cage and tied for fixation, then tied to the beam stirrups 1-3 to form the beam end reinforcement cage. After the formwork is erected, trapezoidal through-section beam shear groove key 3-4 is set at the junction of the beam and the node, and then ordinary concrete 5 is poured to complete the prefabrication.

[0022] See Figure 8 , 9 At the post-cast UHPC-X-shaped steel reinforcement lapped beam-column node 3, to avoid conflict with the bent longitudinal reinforcement, the bending length of the bottom bent longitudinal reinforcement 2-2 is approximately half the diagonal length, and the bottom bent longitudinal reinforcement 2-2 is fixed by lap binding. The top additional longitudinal reinforcement 3-1 and the bottom additional longitudinal reinforcement 3-2 of the node are small-diameter hook reinforcements. The top additional longitudinal reinforcement 3-1 and the bottom additional longitudinal reinforcement 3-2 of the node are placed close to the bent longitudinal reinforcement and are cast integrally with the precast concrete column 1 and the precast concrete beam 2. They are staggered at the connection point to form the steel reinforcement skeleton of the post-cast UHPC-X-shaped steel reinforcement lapped beam-column node 3.

[0023] See Figure 11 The bent longitudinal bars of the precast concrete beam 2 (including the top bent longitudinal bar 2-1 and the bottom bent longitudinal bar 2-2) are tied tightly to the inner edge of the bent longitudinal bars of the precast concrete column 1 (including the top bent longitudinal bar 1-4 and the bottom bent longitudinal bar 1-5). The first half-X-shaped structure and the second half-X-shaped structure are tied together to form an X-shaped steel reinforcement lap splice. Ultra-high performance concrete 4 is poured outside the X-shaped steel reinforcement lap splice to form an integral post-cast UHPC-X-shaped steel reinforcement lap beam-column node 3. The height of the post-cast UHPC-X-shaped steel reinforcement lap beam-column node 3 is located at 1 / 2 of the height of the column 1, and its core area is located at approximately two-ninths of the beam span from the precast concrete column 1.

[0024] Furthermore, the lengths of the beam end shear grooves 3-3 and 3-4 are one-third of the beam height, with a depth of approximately 80-100 mm. The groove angle is set between 30° and 60° to enhance the shear resistance of the joint and the interlocking ability of the interface. The bending angles of the bent steel bars (i.e., the top bent longitudinal bars 1-4, the bottom bent longitudinal bars 1-5, the top bent longitudinal bars 2-1, and the bottom bent longitudinal bars 2-2) are 28°-35°, and the lap length is 10 times the diameter of the steel bar, including the projected length of the bend. The connection area length of the post-cast UHPC-X-shaped steel bar lapped beam-column joint 3 is the lap length of the steel bar plus 50-60 mm (rounded to the nearest integer) to ensure uniform stress and structural integrity in the lap area.

[0025] The installation process of the UHPC-steel hybrid connection high-performance precast concrete beam-column joint of this utility model is as follows: 1) Tie the steel cage of the precast concrete column 1. Insert the top bent longitudinal bar 1-4, the bottom bent longitudinal bar 1-5, the top additional longitudinal bar 3-1, and the bottom additional longitudinal bar 3-2 of the node into the steel cage at the column end and tie them at the designated positions. 2) Tie the beam stirrups 1-3 to form the beam end reinforcement cage, set up the formwork and pour concrete for 5 curing, and the precast concrete column 1 is completed; 3) Fabricate precast concrete beam 2, tie beam reinforcement cage, tie the top bent longitudinal bar 2-1, the bottom bent longitudinal bar 2-2, the top additional longitudinal bar 3-1 of the node, and the bottom additional longitudinal bar 3-2 of the node into the beam reinforcement cage at the designated position, set up formwork and pour concrete 5 for curing, and the precast concrete beam 2 is completed. 4) Hoist the precast concrete beam 2 onto the precast concrete column 1, and position and tie the top bent longitudinal bars 1-4 and bottom bent longitudinal bars 1-5 of the beam end to the top bent longitudinal bars 2-1 of the beam end to form an X-shaped steel bar lap splice. Then, perform secondary partial formwork to pour ultra-high performance concrete 4 (UHPC) and cure it to complete the assembly.

[0026] This invention combines UHPC (Ultra-High-Strength Polymer) with X-shaped rebar lap joints, utilizing the high strength and toughness of UHPC and the stable support of X-shaped rebars to propose a high-performance prefabricated concrete beam-column joint employing UHPC-X-shaped rebar lap joints. Its superior mechanical properties significantly improve the overall seismic performance of prefabricated concrete frame structures. This invention minimizes the wet connection length in prefabricated construction. The excellent bond between UHPC and rebar ensures effective force transfer in the lapped rebars and significantly shortens the lap length, while also noticeably reducing concrete usage and material costs. Although UHPC has a higher material cost, its longer service life and superior performance reduce future maintenance and repair costs; the maintenance and repair costs of UHPC can be 20%-30% lower than those of ordinary concrete. This invention enables rapid construction of prefabricated wet connections. UHPC, with its self-leveling properties, requires no vibration and exhibits rapid early strength development, reaching a strength of over 50 MPa within one day of pouring, meeting the strength requirements of the connection section and significantly reducing the curing time of the connection area. This invention also significantly reduces on-site wet work, minimizes construction waste, and avoids excessive material and energy consumption during support-free construction. It eliminates waste from the removal of temporary supports, and UHPC raw materials use less cement, have low carbon dioxide emissions during production, and offer long durability. The overall structural efficiency of this invention is high. Prefabricated structural components in the factory and rapid on-site assembly and connection shorten the construction cycle, improve project quality and stability, reduce subsequent maintenance and repair costs, and enhance the overall aesthetics of the structure. These factors indirectly reduce construction costs and improve structural efficiency. In conclusion, this invention combines the superior properties of high-performance materials with rapid assembly and connection technology, proposing a green, efficient, highly reliable, and promising new prefabricated wet connection technology that aligns well with the development direction of building industrialization and provides a new approach for the application of prefabricated concrete structures.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this utility model. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this utility model should be covered within the protection scope of the claims of this utility model.

Claims

1. A high-performance prefabricated concrete beam-column joint using UHPC-X-shaped steel reinforcement lap splicing, characterized in that, The beam-column joint (3) includes the top bent longitudinal reinforcement (1-4), the bottom bent longitudinal reinforcement (1-5), the top bent longitudinal reinforcement (2-1), and the bottom bent longitudinal reinforcement (2-2). The top bent longitudinal bar (1-4) and the bottom bent longitudinal bar (1-5) of the beam end are lapped together at the middle of the beam end to form the first half X-shaped structure. The top bent longitudinal bar (1-4) and the bottom bent longitudinal bar (1-5) of the beam end are vertically inserted into the column reinforcement cage for fixation. The top bent longitudinal bar (1-4) and the bottom bent longitudinal bar (1-5) of the beam end are tied with the beam stirrups (1-3) to form the beam end reinforcement cage. The top bent longitudinal bar (2-1) and the bottom bent longitudinal bar (2-2) of the beam are lapped together at the middle of the beam end to form a second half X-shaped structure. The top bent longitudinal bar (2-1) and the bottom bent longitudinal bar (2-2) of the beam are vertically inserted into the column reinforcement cage for fixation. The top bent longitudinal bar (2-1) and the bottom bent longitudinal bar (2-2) of the beam are tied with the beam stirrups (1-3) to form the beam end reinforcement cage. The first half of the X-shaped structure and the second half of the X-shaped structure are tied together to form an X-shaped steel reinforcement lap joint, and ultra-high performance concrete is poured on the outside of the X-shaped steel reinforcement lap joint (4).

2. The high-performance precast concrete beam-column joint using UHPC-X-shaped steel reinforcement lap splicing as described in claim 1, characterized in that, One end of the longitudinal reinforcement (1-4) at the top of the beam end is bent at an angle to the bottom of the beam, and the other end is bent at a right angle. The angled bend and the right angle bend are set parallel to each other.

3. A high-performance prefabricated concrete beam-column joint using UHPC-X-shaped steel reinforcement lap splicing as described in claim 1, characterized in that, One end of the longitudinal reinforcement (1-5) at the bottom of the beam end is bent at an angle to the middle of the beam height, and the other end is bent at a right angle. The oblique bend and the right bend are set parallel to each other.

4. A high-performance precast concrete beam-column joint using UHPC-X-shaped steel reinforcement lap splicing as described in claim 1, characterized in that, One end of the longitudinal reinforcement (2-1) at the top of the beam is bent at an angle to the bottom of the beam, and the other end is bent at a right angle. The angled bend and the right angle bend are set parallel to each other.

5. A high-performance prefabricated concrete beam-column joint using UHPC-X-shaped steel reinforcement lap splicing as described in claim 1, characterized in that, One end of the longitudinal reinforcement (2-2) at the bottom of the beam is bent at an angle to the middle of the beam height, and the other end is bent at a right angle. The angled bend and the right angle bend are set parallel to each other.

6. A high-performance precast concrete beam-column joint using UHPC-X-shaped steel reinforcement lap splicing as described in claim 1, characterized in that, The X-shaped steel bar lap splice is provided with additional longitudinal reinforcement (3-1) at the top of the node, and additional longitudinal reinforcement (3-2) at the bottom of the node is provided at the bottom of the node.

7. A high-performance precast concrete beam-column joint using UHPC-X-shaped steel reinforcement lap splicing as described in claim 1, characterized in that, The beam-column joint (3) and the two joint surfaces of the beam end are respectively provided with beam end shear groove key (3-3) and beam shear groove key (3-4).

8. A high-performance precast concrete beam-column joint using UHPC-X-shaped steel reinforcement lap splicing as described in claim 7, characterized in that, The joint between the beam end shear groove key (3-3) and the beam end, as well as the joint between the beam shear groove key (3-4) and the beam, are all trapezoidal through sections.

9. A high-performance precast concrete beam-column joint using UHPC-X-shaped steel reinforcement lap splicing as described in claim 7 or 8, characterized in that, The lengths of the beam end shear groove key (3-3) and the beam shear groove key (3-4) are 1 / 3 of the beam height.

10. A high-performance precast concrete beam-column joint using UHPC-X-shaped steel reinforcement lap splicing as described in claim 1, characterized in that, The bending length of the longitudinal reinforcement (2-2) at the bottom of the beam is half the length of the diagonal.

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