Prestressed fabricated concrete beam-column joint and construction method thereof

Abstract

The present application relates to a kind of prestressed assembly type concrete beam column joint and its construction method, comprising: reinforced concrete column, prefabricated prestressed beam, prestressed steel strand;Two ends of prestressed steel strand extend from prefabricated prestressed beam, wherein: part of prestressed steel strand 90 ° after bending in the lower part of prefabricated prestressed beam is anchored in beam-column joint by bending anchoring, the rest of the prestressed steel strand in the upper and lower parts of prefabricated prestressed beam is not bent, and the stretching part is post-tensioned by anchor and anchor pad by post-tensioning method to realize the prestress applied to the concrete of beam-column joint area;The present application combines pre-tensioning method and post-tensioning method on the same steel strand, uses cast-in-place high-performance concrete in joint area, enhances the ductility, shear capacity, crack resistance and anchoring performance of reinforcement of joint, and the construction method is simple, efficient, and the joint performance is reliable, can significantly improve the seismic performance of frame joint.

Description

Technical Field

[0001] This invention relates to the field of prefabricated building technology, and in particular to a prestressed prefabricated concrete beam-column joint and its construction method. Background Technology

[0002] Building industrialization is an inevitable development trend for my country's construction industry now and in the future, and prefabricated construction is an effective way to achieve building industrialization. Prefabricated construction refers to the prefabrication of building components in component factories, their mechanical transportation to the construction site, and assembly on-site to complete the construction of the building. Compared with traditional cast-in-place construction, prefabricated construction has a significant emission reduction effect and can effectively reduce construction dust and noise pollution.

[0003] There are three main structural forms of prefabricated buildings: prefabricated concrete structures, prefabricated steel structures, and prefabricated timber structures. Prefabricated concrete structures are currently the most widely used and researched prefabricated structural system both domestically and internationally. Based on structural system, prefabricated concrete structures are divided into frame structures and shear wall structures. Among them, prefabricated concrete frame structures offer flexible interior space layouts and diverse building facades, and are widely used in public, residential, and industrial buildings.

[0004] As a type of precast concrete frame structure, precast prestressed concrete frame structure combines the characteristics of precast and prestressed structures. The application of prestress helps improve the performance and integrity of precast concrete frame structure, and promotes the application of precast concrete frame structure in large-span and heavy-load structures. Currently, there are two main types of precast prestressed concrete frame structures commonly used in engineering. One type consists of precast prestressed beams and cast-in-place non-prestressed joints. In this type of structure, prestress is applied only to the beams, while the joints are cast-in-place concrete without prestress. This type of structure has poor load-bearing capacity, ductility, deformation capacity, and deformation recovery capacity. The crack resistance at the beam-column interface is also poor, and the crack width is often large. The other type consists of precast prestressed beams and precast prestressed joints. In this type of structure, prestress is applied not only to the precast beams but also to the joints, which are precast and prestressed by tensioning post-tensioned prestressing tendons that pass through the core area of ​​the precast joint. However, in this structure, the beams and joints are precast separately, and the concrete of the two is not integrated. The precast beams and precast joints are mainly connected by prestressing tendons. The beam-column joints of this type of structural system exhibit obvious semi-rigid characteristics, and the stiffness and energy dissipation capacity are significantly different from those of cast-in-place frames.

[0005] The beam-column joint area is a weak point in precast concrete frame structures. The connection of the beam-column joint directly affects the stability and seismic resistance of the overall structure, especially for precast prestressed concrete frame structures mainly used in large-span, heavy-load structures. To ensure that the joint area of ​​precast prestressed concrete frame structures has good mechanical properties and further improve the safety of the overall structure, it is necessary to further upgrade and optimize the joint construction of precast prestressed concrete frame structures. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the problem of weak mechanical properties at the beam-column joint position in the prefabricated concrete frame structure in the prior art, and to provide a prestressed prefabricated concrete beam-column joint and its construction method, so as to further upgrade and optimize the beam-column joint structure of the prefabricated prestressed concrete frame structure, so as to have good mechanical properties and further improve the safety of the overall structure.

[0007] To solve the above-mentioned technical problems, the present invention provides a prestressed precast concrete beam-column joint, comprising:

[0008] reinforced concrete column;

[0009] The beam-column joint, cast on the reinforced concrete column, includes: a pre-cast part of the beam-column joint and a post-cast part of the beam-column joint, with a tensioning groove reserved in the post-cast part of the beam-column joint;

[0010] A precast prestressed beam is connected to the reinforced concrete column through the beam-column joint;

[0011] Prestressed steel strands are distributed at the upper and lower parts of the precast prestressed beam. Both ends of the prestressed steel strands extend from the precast prestressed beam. Specifically, the prestressed steel strands located at the lower part of the precast prestressed beam are bent at 90° and then anchored to the beam-column joint by bending anchorage. The remaining prestressed steel strands located at the upper and lower parts of the precast prestressed beam are not bent. After the cast-in-place concrete in the joint area reaches the design strength, the extended parts are post-tensioned using anchorages and anchor plates to apply prestress to the concrete in the beam-column joint area.

[0012] In one embodiment of the present invention, the prestressed steel strands located in the upper part of the precast prestressed beam are prestressed using a pre-tensioning construction process and bonded to the concrete inside the precast prestressed beam in an adhesive manner.

[0013] In one embodiment of the present invention, all the prestressed steel strands located in the lower part of the precast prestressed beam are prestressed using the pre-tensioning construction process and bonded to the concrete in the precast prestressed beam in a bonded manner.

[0014] Alternatively, prestress can be applied to only a portion of the prestressed steel strands using the pre-tensioning method, while the remaining prestressed steel strands are not bonded to the concrete during beam fabrication. Prestress can then be applied to the precast prestressed beam and the concrete in the joint area using the post-tensioning method after the beam-column joint assembly is completed.

[0015] In one embodiment of the present invention, the portion of the prestressed steel strand extending out of the precast prestressed beam is coated with construction grease, and a corrugated pipe with an inner diameter larger than that of the prestressed steel strand is fitted over it to achieve a non-bonded connection with the concrete in the joint area.

[0016] In one embodiment of the present invention, a slow-bonding material is applied to the portion of the prestressed steel strand extending out of the precast prestressed beam, and a corrugated pipe with an inner diameter larger than that of the prestressed steel strand is fitted over it to achieve a bonded connection with the concrete in the joint area.

[0017] In one embodiment of the present invention, steel mesh is arranged in the anchorage concrete of the end of the precast prestressed beam and the post-tensioning part of the joint area.

[0018] In one embodiment of the present invention, column reinforcement and column stirrups are also included, which are disposed in the reinforced concrete column. Multiple column reinforcements are disposed along the extension direction of the reinforced concrete column. The column stirrups are generally in the form of a closed rectangle connecting multiple column reinforcements. Each set of column stirrups is formed by welding two "C"-shaped sub-reinforcements at their overlapping positions to form a closed rectangle.

[0019] In one embodiment of the present invention, the anchor consists of a clamp, an anchor ring, and an anchor ring nut. The outer surface of the anchor ring and the inner surface of the anchor ring nut have threads that cooperate with each other, and the anchor ring can be screwed into the anchor ring nut through the threads.

[0020] In one embodiment of the present invention, the anchor plate is a high-strength steel plate with through holes for reinforcing bars, the diameter of which is larger than the outer diameter of the corrugated pipe fitted around the prestressed steel strand; four anchor bars perpendicular to the surface of the plate are welded to the side of the anchor plate closest to the concrete, and the anchor bars are used to anchor the anchor plate into the concrete of the joint area.

[0021] To address the aforementioned technical problems, the present invention also provides a construction method for a prestressed precast concrete beam-column joint, used to prepare the prestressed precast concrete beam-column joint, comprising the following steps:

[0022] S1. Fabrication of precast prestressed beams;

[0023] S2. Cast reinforced concrete columns;

[0024] S3, steel strand at the bent beam end;

[0025] S4. Handling and hoisting precast prestressed beams;

[0026] S5, outer corrugated pipe;

[0027] S6. Tie the column stirrups;

[0028] S7. Fixed cavity mold;

[0029] S8, Fixed bellows;

[0030] S9. Concrete poured after the beam-column joint is poured;

[0031] S10, tensioning steel strands at the end of the tensioning beam;

[0032] S11, cutting reinforcement bars and sealing anchors.

[0033] The technical solution of the present invention has the following advantages compared with the prior art:

[0034] Traditional precast prestressed beams and cast-in-place non-prestressed joints are merely prestressed structural components, not a prestressed structural system. This invention, a prestressed precast concrete beam-column joint and its construction method, innovatively proposes a beam-column connection combining bent steel strand group anchorage and post-tensioned prestressing anchorage, upgrading the structure to a prestressed structural component and system. Simultaneous application of prestress in the joint area and the precast prestressed beam enhances the connection performance between the beam and the joint area, as well as the crack resistance of the beam-column interface, significantly improving the seismic performance of the joint. Furthermore, the cast-in-place concrete in the joint area further increases the overall integrity of the beam-column connection.

[0035] This invention combines pre-tensioning and post-tensioning. Pre-tensioning is used to fabricate prestressed beams, and after the cast-in-place concrete in the joint area reaches its design strength, post-tensioning is applied to the steel strands at the beam ends. Although the post-tensioned steel strands in the joint area and the pre-tensioned steel strands in the prestressed beam are the same strands, the tensioning is performed in different areas and stages. This ensures that the prestressing effects of the steel strands in the joint area and the same strands in the prestressed beam are independent. If some prestress is lost or disappears, the impact on the prestress of the remaining portion is minimal, thereby improving the reliability of the structure.

[0036] This invention applies prestress to a portion of the steel strands in the lower part of the precast prestressed beam using a pre-tensioning method, while the other portion of the prestressed steel strands are prestressed by a post-tensioning method after the beam-column joint is assembled. This can compensate for the prestress loss that occurs during the storage, transportation and assembly of the prestressed beam, thereby reducing the prestress loss of the beam. Attached Figure Description

[0037] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0038] Figure 1 This is a schematic diagram of the overall structure of the node in this invention;

[0039] Figure 2 A schematic diagram showing the concrete pouring sequence in the node area;

[0040] Figure 3 This is a schematic diagram of the beam-column joint area of ​​the present invention;

[0041] Figure 4 This is a schematic diagram of the reinforcement in the mid-node area of ​​the present invention;

[0042] Figure 5 This is a schematic diagram of the reinforcement at the beam end of the mid-node in this invention;

[0043] Figure 6 This is a schematic diagram of the reinforcement at the right end of the middle node of the present invention;

[0044] Figure 7 This is a schematic diagram of the reinforcement at the left end of the middle node of the present invention;

[0045] Figure 8 This is a schematic diagram of the beam reinforcement of the present invention;

[0046] Figure 9 This is a schematic diagram of ordinary energy-dissipating steel bars inside the beam according to the present invention;

[0047] Figure 10 This is a schematic diagram of the sectionalization of the bent steel strand of the present invention;

[0048] Figure 11 This is a schematic diagram of the post-tensioned steel strand partitioning of the present invention;

[0049] Figure 12 This is a schematic diagram of the overall edge node of the present invention;

[0050] Figure 13 This is a schematic diagram of the reinforcement of the edge nodes of the present invention;

[0051] Figure 14 This is a schematic diagram of the reinforcement at the beam end of the edge node of the present invention;

[0052] Figure 15 This is a schematic diagram of the column reinforcement and stirrups in the node area of ​​the present invention;

[0053] Figure 16 This is an exploded view of the stirrups in the node area of ​​the present invention;

[0054] Figure 17 This is a schematic diagram of the anchorage of the present invention;

[0055] Figure 18 This is a schematic diagram of the anchor plate of the present invention;

[0056] Figure 19 This is a flowchart of the node construction method of the present invention.

[0057] Explanation of reference numerals in the accompanying drawings: 1. Reinforced concrete column; 2. Beam-column joint; 3. Precast prestressed beam; 4. Tensioning groove; 5. Composite floor slab; 6. Column reinforcement; 7. Column stirrups; 8. Composite layer reinforcement; 9. Beam stirrups; 10. Secondary tension prestressed steel strand; 11. Anchorage; 12. Anchor plate; 13. Bent anchorage steel strand; 14. Ordinary steel reinforcement; 15. Beam end reinforcement mesh; 16. Reinforcement mesh within the beam-column joint; 20 1. Pre-cast portion of beam-column joint; 202. Post-cast portion of beam-column joint; 701. Sub-reinforcement bar; 1001. Pre-tensioned section of secondary tensioned prestressed steel strand; 1002. Post-tensioned section of secondary tensioned prestressed steel strand; 1101. Wedge; 1102. Anchor ring; 1103. Anchor ring nut; 1201. Through-reinforcement hole; 1202. Anchor bar; 1301. Pre-tensioned section of bent anchored steel strand; 1302. Bent section of bent anchored steel strand. Detailed Implementation

[0058] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0059] Example 1

[0060] Reference Figures 1 to 7 As shown in Figures 1 and 2, the prestressed precast concrete beam-column joint of the present invention includes:

[0061] Reinforced concrete column 1;

[0062] The beam-column joint 2 is cast on the reinforced concrete column 1 and includes: the pre-cast part 201 of the beam-column joint and the post-cast part 202 of the beam-column joint. A tensioning groove 4 is reserved in the post-cast part 202 of the beam-column joint.

[0063] The precast prestressed beam 3 is connected to the reinforced concrete column 1 through the beam-column joint 2;

[0064] Prestressed steel strands are distributed at the upper and lower parts of the precast prestressed beam 3. Both ends of the prestressed steel strands extend from the precast prestressed beam 3. Among them, the prestressed steel strands located at the lower part of the precast prestressed beam 3 are bent at 90° and then anchored to the beam-column joint 2 by bending anchorage. The remaining prestressed steel strands located at the upper and lower parts of the precast prestressed beam 3 are not bent. After the cast-in-place concrete in the joint area reaches the design strength, the extended parts are post-tensioned by means of anchorage 11 and anchor plate 12 to apply prestress to the concrete in the beam-column joint 2 area.

[0065] Traditional precast prestressed beams 3 and cast-in-place non-prestressed joints are merely prestressed structural components, not a prestressed structural system. This invention, the prestressed precast concrete beam-column joint 2 and its construction method, innovatively proposes a beam-column connection combining bent steel strand group anchorage and post-tensioned prestressing anchorage, upgrading the structure to a prestressed structural component and system. Simultaneous prestressing in the joint area and the precast prestressed beam 3 enhances the connection performance between the beam and the joint area, as well as the crack resistance of the beam-column interface, significantly improving the seismic performance of the joint. Furthermore, the cast-in-place concrete in the joint area further increases the overall integrity of the beam-column connection.

[0066] This invention combines pre-tensioning and post-tensioning. Pre-tensioning is used to fabricate the precast prestressed beam 3. After the cast-in-place concrete in the joint area reaches its design strength, post-tensioning is then used to tension the steel strands at the beam ends. Although the post-tensioned steel strands in the joint area and the pre-tensioned steel strands in the precast prestressed beam 3 are the same steel strands, they are tensioned in different areas and stages. This ensures that the prestressing effects of the steel strands in the joint area and the same steel strands in the precast prestressed beam 3 are independent. If some prestress is lost or disappears, the impact on the prestress of the other part is relatively small, thereby improving the reliability of the structure.

[0067] This invention applies prestress to a portion of the steel strands in the lower part of the precast prestressed beam 3 using a pre-tensioning method, and applies prestress to the other portion of the prestressed steel strands using a post-tensioning method after the beam-column node 2 is assembled. This can compensate for the prestress loss that occurs during the storage, transportation and assembly of the prestressed beam, thereby reducing the prestress loss of the beam.

[0068] The beam-column joint 2 is poured in two stages. The first stage is the pre-poured portion 201 of the beam-column joint, which is poured together with the column below the beam-column joint 2. The second stage is the post-poured portion 202 of the beam-column joint, which is poured after the precast prestressed beam 3 is hoisted to the design position. The precast prestressed beam 3 extends into the post-poured portion 202 of the beam-column joint to a certain depth so that the interface between the new and old concrete of the precast prestressed beam 3 and the post-poured portion 202 of the beam-column joint avoids the beam-column interface, which can enhance the crack resistance at the beam-column interface.

[0069] The beam-column joint area 2 can use either ordinary concrete or high-performance concrete. For example, self-stressing high-performance concrete can further increase the prestress of the concrete in the joint area through its own micro-expansion during the solidification process, thereby improving the shear strength and stiffness of the joint area and enhancing the anchorage performance of the reinforcement. Self-stressing fiber-reinforced cement-based composite materials are made by incorporating ultra-high-performance ultra-fine short steel fibers into self-stressing high-performance concrete, which can further improve the shear strength, stiffness, and ductility of the joint, while increasing the initial crack load and through crack load, delaying the appearance of cracks, reducing crack width, and improving the bond and anchorage performance between the reinforcement and the concrete. Rapid-curing concrete can significantly reduce the curing time of the concrete, further shortening the construction period.

[0070] The precast prestressed beam 3 is a precast prestressed composite beam, with composite layer steel bars 8 and beam stirrups 9 in the beam; the precast prestressed beam 3 is precast in the factory, and after the beam is hoisted into place, the floor slab 5 is cast on the beam in place at the construction site.

[0071] The precast prestressed beam 3 has prestressed steel strands at both the top and bottom; the upper part of the precast prestressed beam 3 only has secondary tension prestressed steel strands 10, while the lower part of the precast prestressed beam 3 includes secondary tension prestressed steel strands 10 and bent anchoring steel strands 13. (Refer to...) Figures 8-11 As shown, the secondary tensioned prestressed steel strand 10 is divided into three parts. The middle part is the pre-tensioned section 1001 of the secondary tensioned prestressed steel strand. In the production process of the precast prestressed beam 3, the prestress is applied to the concrete of the precast prestressed beam 3 by pre-tensioning and bonded to the precast prestressed beam 3. The other two parts are the post-tensioned sections 1002 of the secondary tensioned prestressed steel strand extending from both ends of the beam. The post-tensioning of the section is carried out after the concrete in the joint area reaches the design strength.

[0072] The bent anchoring steel strand 13 is also divided into three parts. The middle part is the pre-tensioned section 1301 of the bent anchoring steel strand. In the production process of the precast prestressed beam 3, the prestress is applied to the concrete of the precast prestressed beam 3 by pre-tensioning and is bonded to the precast prestressed beam 3. The other two parts are the 90° bent sections 1302 of the bent anchoring steel strand extending from both ends of the beam. These parts are directly poured into the concrete without applying prestress.

[0073] The pre-tensioned section 1001 of the upper secondary tensioning prestressed steel strands in the precast prestressed beam 3 is used to prevent the beam from arching after the prestressed steel strands at the bottom of the precast prestressed beam 3 are released, which would cause cracking of the concrete in the upper part of the precast prestressed beam 3.

[0074] The pre-tensioned sections 1001 of the secondary tensioned prestressed steel strands at the bottom of the precast prestressed beam 3 can all be prestressed using the pre-tensioning construction process and bonded to the concrete inside the precast prestressed beam 3 in an adhesive manner; alternatively, only a few of the pre-tensioned sections 1001 of the secondary tensioned prestressed steel strands can be prestressed using the pre-tensioning method, while the remaining pre-tensioned sections 1001 of the secondary tensioned prestressed steel strands are first coated with building grease and fitted with corrugated pipes during beam fabrication to achieve non-bonding with the concrete. After the beam-column joint 2 is assembled, the prestressed beam 3 and the joint area concrete are prestressed by tensioning the post-tensioned sections 1002 of the secondary tensioned prestressed steel strands.

[0075] The prestressed stress applied by pre-tensioning in the precast prestressed beam 3 and the prestressed stress applied by post-tensioning in the joint area are both 0.7f. tpk , where f tpk This refers to the standard value of the tensile strength of steel strand;

[0076] The secondary tensioning prestressed steel strand post-tensioning section 1002 at the lower part of the precast prestressed beam 3 can be coated with building grease and then fitted with a corrugated pipe with an inner diameter slightly larger than the diameter of the steel strand to achieve a non-bonded connection with the concrete in the joint area.

[0077] The secondary tensioning prestressed steel strand post-tensioning section 1002 at the lower part of the precast prestressed beam 3 can also be coated with a slow-bonding material and then fitted with a corrugated pipe with an inner diameter slightly larger than the diameter of the steel strand to achieve a bonded connection with the concrete in the joint area.

[0078] Ordinary steel bars 14 are also provided in the lower part of the precast prestressed beam 3. The ordinary steel bars 14 in the lower part of the precast prestressed beam 3 are not prestressed and are bonded to the concrete of the precast prestressed beam 3 by means of bonding. The ordinary steel bars 14 can be arranged non-continuously inside the precast prestressed beam 3, with each end extending into the precast prestressed beam 3 to the inflection point and then extending inward by twice the anchorage length. The ordinary steel bars 14 extend a certain length out of the beam ends to enter the joint, and a small steel plate is welded to their ends to increase their anchorage performance in the joint concrete. The ordinary steel bars 14 consume the energy input into the precast prestressed beam 3 under external loads such as earthquakes through their own large plastic deformation, thereby increasing the ductility of the beam.

[0079] In the anchorage zone concrete of the precast prestressed beam ends and the post-tensioning section of the joint area, a certain number of beam end steel mesh 15 and beam-column joint steel mesh 16 are respectively arranged to enhance the local splitting resistance of the concrete in the beam end and joint anchorage zone. The specific number of steel mesh and the diameter of the steel bars are determined by calculation.

[0080] Reference Figures 12-14 As shown, the beam-column joint 2 is constructed using cast-in-place concrete, with a tensioning groove 4 pre-reserved at the designed location during pouring. For the middle joint, the tensioning groove 4 is located between the vertical intersection line of the beam and column and the vertical edge line of the column. For the edge joint, the tensioning groove 4 is located where the steel strand at the beam end extends straight to the opposite column surface. For the middle joint, the post-tensioned steel strand needs to be slightly bent outward in the plane to extend to the tensioning groove 4. For the middle joint, the post-tensioned steel strands at the left and right beam ends are slightly bent outward while also slightly bent up and down to ensure that the post-tensioned steel strands at each beam end are staggered from the corresponding post-tensioned steel strands at the opposite beam end. For the edge joint, the post-tensioned steel strands do not need to be bent and extend straight to the opposite column surface.

[0081] Reference Figure 15 and Figure 16 As shown, the reinforced concrete column 1 contains column bars and column stirrups. Multiple column bars are arranged along the extension direction of the reinforced concrete column 1. The column stirrups are generally in the form of a closed rectangle connecting multiple column bars. Each group of column stirrups is formed by welding two "C"-shaped sub-bars at their overlapping positions to form a closed rectangle.

[0082] Reference Figure 17 As shown, the anchor 11 consists of a wedge 1101, an anchor ring 1102, and an anchor ring nut 1103. The outer surface of the anchor ring 1102 and the inner surface of the anchor ring nut 1103 have mating threads, and the anchor ring can be screwed into the anchor ring nut through the threads. The steel strand is placed between each wedge 1101, and then the wedge and the steel strand are placed into the anchor ring as a whole for tensioning. After tensioning is completed, the anchor ring nut 1103 is tightened to fit tightly against the anchor plate 12 to reduce the retraction of the steel strand after tensioning, thereby reducing the loss of prestress.

[0083] Reference Figure 18 As shown, an anchor plate 12 is arranged in the post-tensioning groove 4 to enhance the local bearing capacity of the concrete in the anchorage zone. The anchor plate 12 is a high-strength steel plate with through holes 1201 on it, the diameter of which is slightly larger than the outer diameter of the corrugated pipe fitted around the steel strand. The position and number of through holes are determined according to the position and number of the steel strands at the beam end to be post-tensioned. Four anchor bars 1202 perpendicular to the plate surface are welded to the side of the anchor plate 12 closest to the concrete. The anchor bars 1202 are used to anchor the anchor plate 12 into the concrete in the joint area.

[0084] Example 2

[0085] Reference Figure 19 As shown, based on the above embodiment 1, this embodiment also provides a construction method for a prestressed precast concrete beam-column joint 2, used to prepare the prestressed precast concrete beam-column joint 2, including the following steps:

[0086] Step 1: Fabrication of precast prestressed beam 3: According to the design plan, precast prestressed beam 3 is fabricated in the factory using the pre-tensioning construction process. First, each prestressed steel strand is tensioned to the design prestress and the beam stirrups are tied. Then, ordinary steel bars 14 are tied at the design position and the beam end steel mesh is fixed at the beam end. Subsequently, the formwork is erected and concrete is poured. After curing to the design strength, the formwork is removed.

[0087] Step 2: Casting reinforced concrete column 1: While fabricating precast prestressed beam 3, cast reinforced concrete column 1 on site or fabricate and cure precast columns in the factory; the cross-sectional dimensions of beam-column joint 2 are larger than the cross-sectional dimensions of the column; beam-column joint 2 is divided into two parts: the precast part 201 and the postcast part 202; the precast part 201 is cast together with the lower reinforced concrete column 1, and the postcast part 202 is cast after the precast prestressed beam 3 is hoisted into place.

[0088] Step 3: Bending the steel strands at the beam ends: After the precast prestressed beam 3 has been cured to the design strength, it is released and the steel strands are cut at the design position; according to the design plan, the steel strands reserved at the beam ends that need to be bent are bent at 90° at the design position;

[0089] Step 4: Transporting and hoisting the precast prestressed beam 3: Transport the precast prestressed beam 3 from the factory to the construction site and hoist the beam to the designed position on the precast part 201 of the beam-column joint. During the hoisting process, pay attention to placing the steel strands at the beam end between the column reinforcement bars in the appropriate position.

[0090] Step 5: Coating with corrugated pipe: Coat the steel strands to be tensioned at the beam end with building grease or a slow bonding material and coat them with a corrugated pipe with an inner diameter slightly larger than the outer diameter of the steel strands to make unbonded or slow-bonded steel strands.

[0091] Step 6: Tie the column stirrups: First, place two "C"-shaped sub-bars near the designed position of the stirrups on the column reinforcement. Then, weld the two sub-bars at the overlapping position to form a whole. Tie the whole column stirrup to the column stirrup at the designed position.

[0092] Step 7: Fixing the cavity formwork: Thread the steel strands to be tensioned at the beam end into the corresponding holes on the cavity formwork, and then fix the cavity formwork at the designed position on the already tied joint area reinforcement cage.

[0093] Step 8: Fixing the corrugated pipe: According to the design position and shape of the steel strand to be tensioned at the beam end, tie the corrugated pipe to the column reinforcement, and tie the steel mesh inside the beam-column node 2 at the design position near the tensioning end of the steel strand.

[0094] Step 9: Pouring 202 concrete for the post-cast portion of the beam-column joint: After setting up the formwork for the 202 post-cast portion of the beam-column joint, pour the appropriate type of concrete, cure it, and then remove the formwork.

[0095] Step 10: Tensioning the steel strands after tensioning the beam end: After the concrete of the post-cast part 202 of the beam-column joint reaches the design strength, place the anchor plate 12 in the cavity formwork, put the anchor 11 on each steel strand that needs to be tensioned, and then use the jack to tension the steel strands at the beam end one by one. After tensioning to the position, tighten the anchor nut outside the anchor ring to the position close to the anchor plate 12, loosen the jack and continue to tension the next steel strand.

[0096] Step 11: Rebar cutting and anchor sealing: After all the steel strands are tensioned, the excess length of each steel strand is cut off, and then the cavity is filled with temporary filling material to facilitate subsequent tensioning; construction is complete.

[0097] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A prestressed precast concrete beam-column joint, characterized in that, include: reinforced concrete column; The beam-column joint is cast on the reinforced concrete column and includes: a pre-cast part of the beam-column joint and a post-cast part of the beam-column joint, wherein a tensioning groove is reserved in the post-cast part of the beam-column joint. A precast prestressed beam is connected to the reinforced concrete column through the beam-column joint; Prestressed steel strands are distributed at the upper and lower parts of the precast prestressed beam. Both ends of the prestressed steel strands extend from the precast prestressed beam. Specifically, the prestressed steel strands at the lower part of the precast prestressed beam are bent at 90° and anchored to the beam-column joint via a bending anchorage method. The remaining prestressed steel strands at the upper and lower parts of the precast prestressed beam are not bent and are divided into a pre-tensioned section in the middle and post-tensioned sections extending to both ends of the beam. The pre-tensioned section is prestressed during the fabrication of the precast prestressed beam using a pre-tensioning method and bonds to the concrete of the precast prestressed beam. The post-tensioned section is tensioned after the cast-in-place concrete in the beam-column joint area reaches its design strength using a post-tensioning method with the aid of anchorages and anchor plates to apply prestress to the concrete in the beam-column joint area.

2. The prestressed precast concrete beam-column joint according to claim 1, characterized in that: Construction grease is applied to the post-tensioned section of the prestressed steel strand at the lower part of the precast prestressed beam, and a corrugated pipe with an inner diameter larger than that of the prestressed steel strand is installed on its outer sleeve to achieve a non-bonded connection with the concrete in the joint area.

3. The prestressed precast concrete beam-column joint according to claim 1, characterized in that: In the post-tensioned section of the prestressed steel strand at the lower part of the precast prestressed beam, a slow-bonding material is applied, and a corrugated pipe with an inner diameter larger than that of the prestressed steel strand is installed on its outer sleeve to achieve a bonded connection with the concrete in the joint area.

4. The prestressed precast concrete beam-column joint according to claim 1, characterized in that: Steel mesh is arranged in the anchorage concrete at the ends of the precast prestressed beams and in the post-tensioning section of the joint area.

5. The prestressed precast concrete beam-column joint according to claim 1, characterized in that: It also includes column bars and column stirrups, which are set in the reinforced concrete column. Multiple column bars are set along the extension direction of the reinforced concrete column. The column stirrups are in the form of a closed rectangle connecting multiple column bars. Each set of column stirrups is formed by welding two "C"-shaped sub-bars at their overlapping positions to form a closed rectangle.

6. The prestressed precast concrete beam-column joint according to claim 1, characterized in that: The anchor consists of a clamp, an anchor ring, and an anchor ring nut. The outer surface of the anchor ring and the inner surface of the anchor ring nut have mating threads, and the anchor ring is screwed into the anchor ring nut through the threads.

7. The prestressed precast concrete beam-column joint according to claim 1, characterized in that: The anchor plate is a high-strength steel plate with through holes for reinforcing bars, the diameter of which is larger than the outer diameter of the corrugated pipe fitted around the prestressed steel strands. Four anchor bars perpendicular to the surface of the plate are welded to the side of the anchor plate closest to the concrete. The anchor bars are used to anchor the anchor plate into the concrete of the joint area.

8. A construction method for a prestressed precast concrete beam-column joint, used to prepare the prestressed precast concrete beam-column joint as described in any one of claims 1 to 7, characterized in that: Includes the following steps: S1. Fabrication of precast prestressed beams; S2. Cast reinforced concrete columns; S3, steel strand at the bent beam end; S4. Handling and hoisting precast prestressed beams; S5, outer corrugated pipe; S6. Tie the column stirrups; S7. Fixed cavity mold; S8, Fixed bellows; S9. Concrete poured after the beam-column joint is poured; S10, tensioning steel strands at the end of the tensioning beam; S11, cutting reinforcement bars and sealing anchors.

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