High-ductility prestressed concrete reinforcement structure and method

Abstract

The application discloses a high-ductility prestressed concrete reinforced structure and method, which comprises a concrete beam main body and anchor plates fixed at both ends of the concrete beam main body; the concrete beam main body is cast-in-situ concrete; a steel reinforcement cage is arranged in the concrete beam main body; the steel reinforcement cage comprises a stirrup group and a composite compression steel reinforcement cage; the composite compression steel reinforcement cage is arranged on the top of the stirrup group and fixedly connected with the stirrup group; at least one corrugated pipe is arranged in the stirrup group and fixedly connected with the stirrup group; and NPR prestressed tendons, the two ends of which extend out of the concrete beam main body, are arranged in the corrugated pipe. The application adopts the composite steel reinforcement cage as the compression zone steel reinforcement, overcomes the damage mode of the compression zone concrete crushing of the NPR steel reinforced concrete structure, adopts the NPR prestressed tendons to improve the tensile performance of the prestressed tendons in the steel reinforced concrete structure, improves the ductility of the structure, and further improves the high ductility of the concrete structure.

Description

High-ductility prestressed concrete reinforced structures and methods Technical Field

[0001] This invention relates to the field of concrete structure technology, specifically to high-ductility prestressed concrete reinforced structures and methods. Background Technology

[0002] In recent years, the number of complex structural projects such as large-span and super high-rise buildings has increased, placing higher demands on the load-bearing performance of reinforced concrete structures. While the application of high-strength steel bars in concrete structures can improve the load-bearing capacity, high-strength steel bars have a shorter yield plateau, making them prone to brittle fracture. Structural systems equipped with high-strength steel bars also have poor ductility, making them susceptible to brittle failure and seriously affecting the safety of the structural system. Therefore, a new material is needed to improve the ductility of high-strength reinforced concrete structures.

[0003] The new NPR material boasts a Poisson's ratio on the order of 10⁻² (with minimal or no necking), a yield strength of 600-1110 MPa, and an ultimate elongation of 30%-70%, solving the problem of brittle fracture caused by the low ultimate elongation of existing high-strength steel reinforcement. Applying this material to building structures can provide both high load-bearing capacity and high ductility. However, experimental results show that the failure mode of concrete beams reinforced with NPR reinforcement is primarily crushing failure of the concrete in the compression zone, with the bottom NPR reinforcement not breaking. The advantages of high strength and high ductility of NPR reinforcement are not fully realized. While concrete beams using NPR reinforcement exhibit good load-bearing capacity and ductility in the tension zone, their load-bearing capacity and ductility in the compression zone remain insufficient.

[0004] When the bearing capacity of the concrete compression zone is insufficient, the concrete will undergo excessive deformation, which may lead to cracks or deformation in the concrete structure, causing it to lose its load-bearing capacity. This can even lead to overall structural instability and structural failure, severely impacting the structure's service life and safety, and posing a significant threat to people and property. Summary of the Invention

[0005] To overcome the above-mentioned technical problems, the present invention provides a high-ductility prestressed concrete reinforced structure and method, which overcomes the failure mode of concrete crushing in the compression zone of NPR reinforced concrete structures and improves the stress performance of the structure.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: It includes a concrete beam body and anchor plates fixed to both ends of the concrete beam body. The concrete beam body is cast-in-place concrete. A reinforcing cage is provided inside the concrete beam body. The reinforcing cage includes a stirrup group and a composite compression reinforcing steel skeleton. The composite compression reinforcing steel skeleton passes through the top of the stirrup group and is fixedly connected to the stirrup group. At least one corrugated pipe is fixedly inserted inside the stirrup group. NPR prestressed tendons extending from both ends of the concrete beam body are provided inside the corrugated pipe. The composite compression reinforcing steel skeleton includes four compression longitudinal bars and steel wire ropes wrapped around the periphery of the longitudinal bars. The surface of the NPR prestressed tendons is spiral ribbed, and grouting material is filled between the corrugated pipe and the NPR prestressed tendons.

[0007] Furthermore, the length of the compression longitudinal reinforcement is 40mm shorter than the main length of the concrete beam, the clear spacing of the compression longitudinal reinforcement is not less than 30mm and not less than 1.5 times the diameter of the compression longitudinal reinforcement, and the spacing of the wire ropes is less than or equal to the clear spacing between two compression longitudinal reinforcements.

[0008] Furthermore, the stirrup group comprises multiple stirrups arranged at intervals.

[0009] Furthermore, holes are left at the corresponding positions of the anchor plate and the NPR prestressed tendon.

[0010] Furthermore, anchorages are fitted at both ends of the NPR prestressed tendons; the anchorages are wedge-type anchorages.

[0011] Furthermore, the length of the corrugated pipe is equal to the length of the main concrete beam, and the inner diameter of the corrugated pipe is 10mm-20mm larger than the outer diameter of the NPR prestressed tendon; the distance between the corrugated pipe and the edge of the main concrete beam is greater than or equal to 30mm, and the distance between corrugated pipes is greater than or equal to 1.5 times the outer diameter of the corrugated pipe.

[0012] The construction method for high-ductility prestressed concrete reinforced structures includes the following steps:

[0013] S1. Lay the bottom mold and apply a release agent to it;

[0014] S2. First, remove the rust from the stirrups and the longitudinal reinforcement under compression, and then tie them: First, fix the top longitudinal reinforcement under compression onto the stirrups to form a steel cage. Use steel wire rope to wrap the longitudinal reinforcement under compression at equal intervals. Use the stirrups as the fixing points during the wrapping process. Weld the steel rope to fix it at both ends of the stirrups.

[0015] S3. Lay the corrugated pipe and fix it in the stirrup group. The circumferential gap at both ends of the corrugated pipe is strictly sealed. Grouting holes are set on the corrugated pipe. The grouting holes are reserved at the ends of the corrugated pipe and also serve as venting holes.

[0016] S4. Prestressed tendon threading: Before threading the tendons, the NPR steel bars are derusted. Then, the NPR steel bars are threaded into one end of the reserved pipe and out the other end of the reserved pipe. The reserved pipe is the corrugated pipe.

[0017] S5. Erect formwork, apply release agent, and pour concrete;

[0018] S6. Curing concrete: After the concrete reaches the design strength, the anchor plate is passed through the NPR steel bar and fixed to both ends of the concrete beam. The wedge-type anchor is sleeved on the protruding end of the NPR steel bar. The NPR steel bar is tensioned by the tensioner. After the control force after tensioning reaches a constant value, the NPR prestressed tendon is formed. The wedge-type anchor self-anchors the NPR prestressed tendon.

[0019] S7. Inject grout into the gap between the NPR prestressed tendon and the corrugated pipe through the grouting hole, and cure the grout to the design strength.

[0020] The beneficial effects of this invention are as follows:

[0021] (1) The present invention uses a composite steel reinforcement cage as the reinforcement in the compression zone, which increases the compressive strength of the reinforcement in the compression zone.

[0022] (2) The steel wire rope in the composite steel reinforcement cage prevents the longitudinal reinforcement from buckling and improves the ductility of the compression zone. In addition, it also constrains the concrete in the core part. By taking advantage of the fact that the compressive strength and ductility of the constrained concrete are greatly improved, the compressive strength of the compression zone is indirectly improved, and the bearing capacity and ductility of the prestressed concrete structure are enhanced.

[0023] (3) Using NPR steel bars as prestressing bars can delay the appearance of cracks in concrete structures; NPR steel bars have high strength and high elongation mechanical properties, which effectively improve the ductility of reinforced concrete structures. Attached Figure Description

[0024] Figure 1 is a schematic cross-sectional view of the high-ductility prestressed concrete reinforced structure of the present invention;

[0025] Figure 2 is a schematic longitudinal section of the high-ductility prestressed concrete reinforced structure of the present invention;

[0026] Figure 3 is a schematic diagram of the composite compression steel skeleton structure of the high ductility prestressed concrete reinforced structure of the present invention;

[0027] In the diagram: 1. Concrete beam main body; 2. Anchor plate; 3. Wedge-type anchor; 4. Stirrup assembly; 5. Composite compression steel reinforcement cage; 51. Compression longitudinal reinforcement; 52. Steel wire rope; 6. Corrugated pipe; 7. NPR prestressed reinforcement; 8. Grouting material; 9. Stirrup. Detailed Implementation

[0028] To make the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the embodiments given are only one way of implementation and do not represent all embodiments.

[0029] Specific implementation method 1:

[0030] As shown in Figures 1, 2, and 3, this embodiment provides a high-ductility prestressed concrete reinforced structure, including a concrete beam body 1 and anchor plates 2 fixed to both ends of the concrete beam body 1. The concrete beam body 1 is made of cast-in-place concrete, and a steel cage is provided inside the concrete beam body 1. The steel cage includes stirrup groups 4 and composite compression steel skeleton 5.

[0031] The composite compression steel reinforcement cage 5 includes four continuous longitudinal compression bars 51 and steel wire ropes 52 wrapped around the four bars. The length of the longitudinal compression bars 51 is 40mm shorter than the length of the main concrete beam 1 to prevent corrosion. The clear spacing of the longitudinal compression bars 51 is not less than 30mm and not less than 1.5 times the diameter of the longitudinal compression bars 51. The steel wire ropes 52 have a diameter of 2mm and are wound around the perimeter of the longitudinal compression bars 51 at equal intervals, with the spacing not exceeding the clear spacing between two longitudinal compression bars 51, to ensure the lateral restraint effect of the steel wire ropes 52 on the concrete, thus forming a strong steel reinforcement cage. When the concrete beam is under load, the composite compression steel reinforcement cage 5 and the concrete inside it bear pressure. At this time, the steel wire ropes 52 around the bars restrain the concrete in the central core part, significantly improving the compressive bearing capacity of this part of the concrete and significantly improving its ductility, thereby preventing the concrete from being crushed prematurely and fully utilizing the bearing capacity of the high-ductility concrete structure.

[0032] The stirrup group 4 consists of multiple stirrups 9 evenly spaced along the length of the concrete beam body 1. Two NPR prestressed bars 7 are threaded through the stirrup group 4. Corrugated pipes 6 are fitted over the NPR prestressed bars 7, positioned at the bottom right angle inside the stirrups 9 and connected to them by wire. The top of the stirrup group 4 is tied with steel wire or directly welded with compression longitudinal bars 51 to make the reinforcement cage more robust. The cross-sectional dimensions of the stirrups are determined by the required net spacing of the duct: the height is the difference between the beam height and the net spacing between the corrugated pipe 6 and the edge of the concrete beam body 1; the width is the difference between the beam width and twice the net spacing between the corrugated pipe 6 and the edge of the concrete beam body 1. To ensure the necessary shear resistance of the concrete beam and to ensure that at least one stirrup 9 passes through each crack, and to control the width of diagonal cracks under service load, the spacing of the stirrups 9 should meet the maximum stirrup spacing requirements in the code.

[0033] The length of the corrugated pipe 6 is equal to the length of the concrete beam body 1. The inner diameter of the corrugated pipe 6 is 10mm-20mm larger than the outer diameter of the NPR prestressed tendon 7. The distance between the corrugated pipe 6 and the edge of the concrete beam body 1 is greater than or equal to 30mm, and the distance between the corrugated pipes 6 is greater than or equal to 1.5 times the outer diameter of the corrugated pipe 6. The main function of the corrugated pipe 6 is to reserve channels for the NPR prestressed tendon 7. Grouting material 8 is provided between the corrugated pipe 6 and the NPR prestressed tendon 7. The grouting material 8 can be cement paste. The surface of the NPR prestressed tendon 7 has spiral ribs, which can achieve good adhesion with the cement paste and ensure its normal operation.

[0034] NPR steel bars are high-strength and high-ductility steel bars with a Poisson's ratio on the order of 10⁻² (with little or no necking), yield strength of 600-1110 MPa, and ultimate elongation of 30%-70%. They possess the characteristics of constant resistance and large deformation, achieving a combination of high load-bearing capacity and high elongation in high-strength steel bars. As prestressed steel bars, NPR steel bars can fully utilize the high strength, high elongation, and constant resistance and large deformation mechanical properties of the steel bars.

[0035] Anchor plate 2 is a steel plate with holes corresponding to the NPR prestressing tendon 7. Anchor plate 2 passes through the NPR prestressing tendon 7 and is attached to the corrugated pipe 6 ducts at both ends of the concrete beam using structural adhesive. This method avoids stress concentration after prestressing and prevents the end concrete from being crushed. The width of anchor plate 2 is equal to the width of the beam section, the height is twice the distance from the NPR prestressing tendon 7 to the bottom of the beam, and the thickness is not less than 3mm. To ensure smooth passage of the NPR prestressing tendon 7, the diameter of the hole is about 2mm larger than the outer diameter of the reinforcing bar.

[0036] The wedge-type anchor 3 is selected according to the diameter of the NPR prestressed tendon 7. It has excellent self-anchoring performance during tensioning, is easy to construct and operate, has a high anchoring compliance coefficient, and has stable and reliable anchoring performance. It is installed at both ends of the NPR prestressed tendon 7 and achieves self-anchoring after tensioning.

[0037] Specific implementation method 2:

[0038] This embodiment provides a construction method for a high-ductility prestressed concrete reinforced structure, including the following steps:

[0039] S1. Lay out the bottom mold and apply a release agent to it.

[0040] S2. First, remove rust from the stirrups and longitudinal reinforcement 51, and then tie them. Considering the ease of winding the wire rope 52, first tie or weld the top four longitudinal reinforcements 51 to the stirrups to form a reinforcement cage. Then, use the wire rope 52 to wind the four longitudinal reinforcements 51 at 50mm intervals. Use the stirrups 9 as fixed points during the winding process to avoid changes in the winding spacing caused by excessive winding distance. Weld the wire rope 52 at both ends of the stirrups 9 to ensure that the wire rope 52 plays its role in confining the concrete.

[0041] S3. Laying Corrugated Pipe 6. Bind the corrugated pipe 6 with thin iron wire at the two right angles at the bottom inside the stirrup 9. The circumferential gaps at both ends of the corrugated pipe 6 must be strictly sealed. During installation, welding slag must not be allowed to splash onto the surface of the corrugated pipe 6, causing it to suffer other mechanical damage. A grouting hole, which also serves as a vent, is set on the corrugated pipe 6. The grouting hole is pre-positioned at the end of the corrugated pipe 6. A 25 mm diameter grouting pipe is installed on the corrugated pipe 6, and its upper part is covered with a sponge and a special plastic cover plate. A 25 mm diameter plastic pipe is then connected to the nozzle of the cover plate, with one end of the plastic pipe extending at least 0.5 meters beyond the side of the beam. To ensure sufficient strength and prevent deformation during grouting concrete pouring, a short steel bar can be inserted inside the plastic pipe. After the concrete pouring is completed, the bar is pulled out, and the pipe opening is sealed with adhesive tape to prevent external debris from falling into the pipe.

[0042] S4. Prestressed Reinforcing Steel Threading. Before threading, the NPR reinforcing steel bars must be derusted. Then, the NPR reinforcing steel bars are threaded through one end of the reserved conduit and out the other end. The reserved conduit is the corrugated pipe 6. Before threading, the duct should be thoroughly inspected to ensure it is intact and unobstructed. If any blockage is found, measures must be taken to clear it.

[0043] S5. Erecting the formwork, applying the release agent, and pouring concrete.

[0044] S6. After the concrete has cured for 28 days and reached its design strength, install the working anchor plate 2, the wedge-type anchor 3, the limiting plate, and the jack. First, the anchor plate 2 passes through the NPR reinforcement and is attached to the corrugated pipe 6 holes at both ends of the concrete beam. The wedge-type anchor 3 is fitted onto the protruding end of the NPR reinforcement. The NPR reinforcement is tensioned by an oil pump. After the control force after tensioning reaches a constant value, the NPR prestressed tendon 7 is formed. The wedge-type anchor 3 self-anchors the NPR prestressed tendon 7.

[0045] S7. Grouting material 8 is injected into the gap between NPR prestressed tendon 7 and corrugated pipe 6 through grouting holes. Grouting material 8 can be cement paste. The injected cement paste is cured to reach the design strength, so that it forms a whole with the concrete, giving full play to its high strength and high elongation mechanical properties, and improving the load-bearing capacity and ductility of the structure.

[0046] Compared with traditional NPR reinforced concrete structures, this disclosure uses a composite steel reinforcement cage as the compression zone reinforcement, increasing the compressive strength of the compression zone reinforcement; the steel wire rope 52 prevents the buckling of the compression longitudinal reinforcement 51, improving the ductility of the compression zone; in addition, it also constrains the concrete in the core part, and by utilizing the significantly improved compressive strength and ductility of the constrained concrete, it indirectly improves the compressive strength of the compression zone, enhancing the load-bearing capacity and ductility of the prestressed concrete structure; the use of high-strength, high-elongation NPR steel bars as prestressing reinforcement delays the appearance of cracks in the structure, effectively improving the ductility of the reinforced concrete structure.

Claims

1. A high-ductility prestressed concrete reinforced structure, comprising a concrete beam body (1) and anchor plates (2) fixed to both ends of the concrete beam body (1), characterized in that, The concrete beam body (1) is made of cast-in-place concrete. A steel cage is provided inside the concrete beam body (1). The steel cage includes a stirrup group (4) and a composite compression steel skeleton (5). The composite compression steel skeleton (5) passes through the top of the stirrup group (4) and is fixedly connected to the stirrup group (4). At least one corrugated pipe (6) is fixed inside the stirrup group (4). NPR prestressed tendons (7) with both ends extending out of the concrete beam body (1) are provided inside the corrugated pipe (6). The composite compression steel skeleton (5) includes four compression longitudinal bars (51) and a steel wire rope (52) wrapped around the compression longitudinal bars (51). The surface of the NPR prestressed tendon (7) is spiral rib. Grouting material (8) is filled between the corrugated pipe (6) and the NPR prestressed tendon (7).

2. According to claim 1, the length of the compression longitudinal reinforcement (51) is 40mm shorter than the length of the concrete beam body (1), the net spacing of the compression longitudinal reinforcement (51) is not less than 30mm and not less than 1.5 times the diameter of the compression longitudinal reinforcement (51), and the spacing of the steel wire rope (52) is less than or equal to the net spacing between two compression longitudinal reinforcements (51).

3. The high-ductility prestressed concrete reinforced structure according to claim 1, characterized in that, The stirrup group (4) includes multiple stirrups (9) arranged at intervals.

4. The high-ductility prestressed concrete reinforced structure according to claim 1, characterized in that, The anchor plate (2) has holes at the corresponding positions of the NPR prestressed tendon (7).

5. The high-ductility prestressed concrete reinforced structure according to claim 3, characterized in that, The NPR prestressed tendon (7) is fitted with anchors at both ends, and the anchors are wedge-type anchors (3).

6. The high-ductility prestressed concrete reinforced structure according to claim 1, characterized in that, The length of the corrugated pipe (6) is equal to the length of the concrete beam body (1), and the inner diameter of the corrugated pipe (6) is 10mm-20mm larger than the outer diameter of the NPR prestressed tendon (7); the distance between the corrugated pipe (6) and the edge of the concrete beam body (1) is greater than or equal to 30mm, and the distance between the corrugated pipes (6) is greater than or equal to 1.5 times the outer diameter of the corrugated pipe (6).

7. The construction method for a high-ductility prestressed concrete reinforced structure as described in claim 5, characterized in that, Includes the following steps: S1. Lay the bottom formwork and apply a release agent to it; S2. First, remove rust from the stirrups and longitudinal reinforcement (51), and then tie them: First, fix the top longitudinal reinforcement (51) to the stirrups to form a reinforcement cage. Use wire rope (52) to wrap the longitudinal reinforcement (51) at equal intervals. Use the stirrups (9) as the fixing points during the wrapping process. Weld the reinforcement ropes at both ends of the stirrups (9) to fix them; S3. Lay the corrugated pipe (6) and fix it inside the stirrup group (4). The circumferential gaps at both ends of the corrugated pipe (6) are strictly sealed. Grouting holes are set on the corrugated pipe (6). The grouting holes are reserved at the ends of the corrugated pipe (6); S4. Thread the prestressed tendons. Before threading the tendons, remove rust from the NPR reinforcement, and then... After the NPR steel bar is inserted into one end of the reserved pipe and then out the other end of the reserved pipe, the reserved pipe is the corrugated pipe (6); S5, set up the formwork, apply the release agent, and pour the concrete; S6, cure the concrete. After the concrete reaches the design strength, pass the anchor plate (2) through the NPR steel bar and fix it to both ends of the concrete beam. The wedge anchor (3) is sleeved on the protruding end of the NPR steel bar. Tensile the NPR steel bar through the tensioner. After the control force after tensioning reaches a constant value, the NPR prestressed tendon (7) is formed. The wedge anchor (3) self-anchors the NPR prestressed tendon (7); S7, inject grout (8) into the gap between the NPR prestressed tendon (7) and the corrugated pipe (6) through the grouting hole. Cure the grout (8) until it reaches the design strength.

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