A UHPC-connected post-tensioned unbonded prestressed concrete perforated beam frame structure system and its design and construction method

Abstract

This invention discloses a post-tensioned unbonded precast prestressed concrete perforated beam frame structure system with UHPC (Ultra-High-Pressure Polymer) connection, comprising a precast concrete upper column, a precast concrete lower column, a post-tensioned unbonded precast prestressed concrete perforated composite beam, a UHPC node core area, and a composite slab. The upper longitudinal main reinforcement extends from the bottom surface of the precast upper column, the lower longitudinal main reinforcement extends from the top surface of the precast lower column, and ordinary steel bars extend from the end face of the precast concrete beam and are directly anchored within the UHPC node core area. This structural system not only facilitates and speeds on-site construction and improves component installation efficiency, but also significantly reduces the anchorage length of the reinforcement, greatly reduces the amount of stirrups in the node core area, avoids reinforcement congestion in the node core area, reduces the component cross-sectional height, lightens the self-weight, and improves the component's crack resistance and load-bearing capacity. The unbonded prestressed tendons provide self-healing properties to the structure, enhancing the overall integrity and structural toughness, thereby improving the seismic performance of the overall frame structure and reducing post-earthquake repair costs.

Description

Technical Field

[0001] This invention relates to the field of precast prestressed prefabricated building construction technology, and more specifically, to a UHPC-connected post-tensioned unbonded precast prestressed concrete perforated beam frame structure system and its design and construction method. Background Technology

[0002] Cast-in-place structures suffer from numerous limitations, including low construction efficiency and high energy consumption, making them increasingly unsuitable for the demands of industrialized building development. Precast concrete structures, with their advantages of rapid construction, factory-produced components, reduced on-site wet work, and reduced environmental pollution, have become the future direction of industrialized building development. After years of development and promotion, precast concrete structures have been widely researched and used.

[0003] Precast concrete frame structures refer to structures where beams and columns are prefabricated in a prefabrication plant and transported to the construction site for connection to form an integral structure. Compared with cast-in-place concrete structures, they offer advantages such as faster construction speed, easier assurance of component quality, higher overall quality, less environmental pollution, reduced labor costs, and savings in formwork and supports, making them a structural form with a very broad prospect. For wet-connection precast concrete frame structures, easy-to-construct and effectively guaranteed integrity of the joint construction form is key to its widespread application. However, based on past earthquake disasters, precast structures have suffered more severe damage in earthquakes, making it difficult to achieve the same seismic performance as cast-in-place structures. To improve the integrity and reliability of the joint connections in precast concrete frames and achieve or even exceed the seismic performance of cast-in-place concrete structures, prestressed technology and UHPC materials have been introduced into precast structures.

[0004] Post-tensioned unbonded prestressed precast concrete structures are structures formed by assembling precast components together using tensioned prestressing tendons. They combine the characteristics of both post-tensioned unbonded prestressed concrete structures and precast structures. The internal stress generated by prestressing in the concrete section can partially or completely offset the stress on the section under service loads, delaying crack initiation and improving the stiffness of the components. Upon unloading, cracks can partially or completely close, demonstrating good elastic recovery performance. Simultaneously, prestressed concrete can fully utilize the material strength of both the prestressing tendons and the concrete, reducing the structure's self-weight. Furthermore, the application of prestressing contributes to improved performance and overall integrity of precast structures, promoting their application in large-span, heavy-load structures.

[0005] UHPC possesses excellent bonding properties, significantly reducing the anchorage length of reinforcing bars and prestressing tendons. Its high strength reduces the amount of stirrups required in the joint core area. Using UHPC in the joint core area simplifies the construction and improves the overall frame integrity. Prestressed structures exhibit excellent load-bearing performance; applying UHPC to the joint core area creates a precast prestressed frame structure. In-depth research on this structure will facilitate the further promotion and application of precast prestressed concrete frame structures. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies and, by leveraging the superior performance of UHPC (Ultra-High-Pressure Concrete), propose a UHPC-connected post-tensioned unbonded precast prestressed concrete perforated beam frame structure system, along with its design and construction methods. This system combines three traditional structural elements: post-tensioned unbonded prestressed structure, prefabricated structure, and composite structure, and utilizes high-performance UHPC materials to improve the seismic performance of precast precast concrete frame structures.

[0007] The advantages of this invention are mainly reflected in two aspects: the connection technology of precast concrete beam-column components and the reinforcement connection technology between components. Regarding component connection technology, beam-column components are connected through high-performance UHPC (Ultra-High-Pressure Polymer) to form a UHPC node core area, making it easier to meet the seismic fortification requirements of strong nodes and weak components, thereby improving the ductility of beam-column nodes and ultimately improving the seismic performance of the overall frame structure. Regarding reinforcement connection technology, the reinforcement between beam-column components only requires simple lap splices with very short lap lengths, significantly saving the fabrication time and on-site installation time of precast components. Therefore, the UHPC-connected post-tensioned unbonded precast prestressed concrete perforated beam frame structure system and its design and construction methods proposed in this invention are in line with my country's green development strategy for building industrialization.

[0008] The technical problem solved by this invention can be achieved by the following technical solutions:

[0009] A UHPC-connected post-tensioned unbonded prestressed concrete perforated beam frame structure system includes a precast concrete upper column, a precast concrete lower column, a post-tensioned unbonded precast prestressed concrete perforated composite beam, a UHPC node core area, and a composite slab.

[0010] The precast concrete upper column is provided with upper longitudinal main reinforcement, and the precast concrete lower column is provided with lower longitudinal main reinforcement. The post-tensioned unbonded precast prestressed concrete perforated composite beam is provided with a precast concrete perforated beam, a beam composite layer and post-tensioned unbonded prestressed tendons. The bottom of the precast concrete perforated beam is provided with ordinary steel bars. If necessary, hanging bars and steel mesh can also be provided around the opening. The steel mesh can also be welded steel mesh. The beam composite layer is provided with top continuous steel bars. The composite slab is composed of a precast concrete slab and a slab composite layer cast on the slab.

[0011] The upper longitudinal main reinforcement extends out of the bottom surface of the precast upper column and is directly anchored in the core area of ​​the UHPC node; the lower longitudinal main reinforcement extends out of the top surface of the precast lower column and is directly anchored in the core area of ​​the UHPC node; and the ordinary steel reinforcement extends out of the end face of the precast concrete perforated beam and is directly anchored in the core area of ​​the UHPC node.

[0012] The unbonded prestressing tendons include straight, broken, or curved prestressing tendons;

[0013] Before pouring the beam-slab composite layer, slab composite layer, and UHPC node core area, the post-tensioned unbonded precast prestressed concrete perforated composite beam is constructed and verified using a force transmission mode adapted to ordinary concrete perforated simply supported beams and bracing. After pouring the node core area, beam-slab composite layer, and slab composite layer, once the concrete strength of the node and composite layer reaches the design requirements, the unbonded prestressing tendons are tensioned. After tensioning, the bracing is removed, and construction stage verification is performed as for frame beams. The cross-section of the upper chord at the opening of the post-tensioned unbonded precast prestressed concrete perforated composite beam differs before and after pouring the beam-slab composite layer, slab composite layer, and UHPC node core area, resulting in different stress states. Therefore, construction verification should be performed on the upper and lower chords at the opening of the precast concrete perforated beam. After the prestress is established, the construction verification and serviceability limit state verification of the unbonded prestressing tendons are calculated based on the effective prestress. When performing the ultimate limit state verification, the stress increment must be considered.

[0014] Furthermore, the post-tensioned unbonded precast prestressed concrete perforated composite beam consists of a precast concrete perforated beam, a beam composite layer, and post-tensioned unbonded prestressing tendons; the composite slab consists of a precast concrete slab and a slab composite layer cast on the slab.

[0015] Furthermore, the post-tensioned unbonded prestressed tendons are embedded in the precast concrete perforated beam members, pass through the core area of ​​the UHPC node and extend beyond the core area of ​​the UHPC node at both ends. Clamps and anchors are fixedly installed at both ends, with one end set on the outside of the column and the other end set in the beam composite layer.

[0016] Furthermore, recessed grooves are provided on the bottom surface of the precast concrete upper column, the top surface of the precast concrete lower column, and the end face of the post-tensioned unbonded precast prestressed concrete perforated composite beam.

[0017] Furthermore, the precast concrete upper column is fixed in the corresponding position using reliable supports.

[0018] Furthermore, the stirrups in the precast concrete upper column, precast concrete lower column, and post-tensioned unbonded precast prestressed concrete perforated composite beam are divided into a dense zone and an undeniable zone. The stirrups in the core area of ​​the UHPC node are arranged according to design requirements. The shear bearing capacity of the core area is calculated according to the diagonal compression member and truss model, and the steel fibers in the UHPC are considered to be equivalent to horizontal stirrups and vertical longitudinal bars, and their contribution to the shear resistance of the core area of ​​the node is considered. At the same time, the beneficial contribution of unbonded prestressed tendons to the shear resistance of the node is also considered.

[0019] Furthermore, the top surface of the precast concrete perforated beam and the precast concrete slab is provided with a rough surface layer.

[0020] This invention also provides a design method for the system, comprising the following steps:

[0021] Step 1: Design beams and columns according to existing specifications and invention patents;

[0022] Step 2: Verify the strength of the upper and lower chords at the opening of the precast concrete perforated beam before casting the beam composite layer, slab composite layer and UHPC node core area of ​​the precast prestressed concrete perforated composite beam.

[0023] Step 3: The opening position in the precast prestressed concrete perforated composite beam should be located in the middle 1 / 3 section as much as possible. When it is located in the end 1 / 3 section of the beam, the distance from the edge of the hole near the node to the inner edge of the node should be greater than 1.5 times the beam height.

[0024] A UHPC-connected post-tensioned unbonded prestressed concrete perforated beam frame structure system includes the following steps:

[0025] Step 1: Fabricate precast concrete lower columns, precast concrete upper columns, precast concrete perforated beams, and precast concrete slabs; among them, sufficient anchorage length must be reserved for the longitudinal reinforcement extending from the precast concrete lower columns and precast concrete upper columns and anchoring them into the core area of ​​the node; sufficient anchorage length must be reserved for the ordinary steel bars extending from the precast concrete perforated beams and anchoring them into the core area of ​​the node; when fabricating precast concrete perforated beams, prestressed tendons should be embedded in the design position, and sufficient length should be reserved at both ends;

[0026] Step 2: After the precast components have cured, hoist the precast concrete lower column and install it on the foundation, and install a sufficient number of stirrups on the extended longitudinal main bars of the lower column;

[0027] Step 3: Hoist the precast concrete perforated beam to the top surface of the precast concrete lower column, so that the bottom surface of the precast concrete perforated beam is flush with the top surface of the precast concrete lower column, and place the end of the precast concrete perforated beam on the precast concrete lower column and fix it with supports; wherein, the ordinary steel bars extending from the precast concrete perforated beams on both sides are reasonably avoided and directly anchored in the core area of ​​the node according to the structural requirements.

[0028] Step 4: Hoist the precast concrete upper column to the top of the precast concrete lower column, and fix the precast concrete upper column in the corresponding position with reliable supports. At this time, tie the stirrups installed in Step 2 to the column longitudinal reinforcement. The longitudinal reinforcements extending from the precast concrete upper and lower columns should be reasonably avoided in the core area of ​​the node and directly anchored.

[0029] Step 5: Pass the top continuous steel bar through the stirrups reserved in the beam composite layer area and the node core area and tie them. Then tie the prestressed tendons embedded and protruding in the precast concrete perforated beam in the node core area according to the design position. Then pour the UHPC node core area and set the formwork so that the UHPC will not enter the beam composite layer.

[0030] Step 6: After the core area of ​​the UHPC node has cured to a sufficient strength, the precast concrete slab (or composite slab, double T slab, secondary beam) is hoisted onto the precast concrete beam and fixed.

[0031] Step 7: Pour the beam composite layer and slab composite layer;

[0032] Step 8: After the composite concrete of the beam and slab layers has cured to sufficient strength, tension the unbonded prestressing tendons.

[0033] Step 9: Repeat the above production process to complete the unbonded prestressed concrete perforated beam frame structure system.

[0034] Compared with the prior art, the advantages of the present invention are as follows:

[0035] 1. This invention combines precast concrete structures with post-tensioned unbonded prestressed structures. It leverages the advantages of precast structures—convenient and rapid construction, high-quality build quality, energy efficiency, and environmental friendliness—while combining them with the advantages of post-tensioned unbonded prestressed structures—which improve structural performance, reduce component cross-sectional height, decrease self-weight, enhance crack resistance, and provide self-healing—thereby improving the overall seismic performance of the frame structure. The unbonded prestressing tendons provide the structure with self-resetting capability, enhancing structural integrity and toughness, and reducing post-earthquake repair costs.

[0036] 2. This invention uses UHPC material with excellent performance. Applying it to the core area of ​​the node can achieve reliable connection of precast beam and column components. It can not only improve the load-bearing capacity and seismic performance of the node, but also significantly reduce the anchorage length of steel bars and prestressed tendons, and significantly reduce the amount of stirrups used in the core area of ​​the node. This avoids steel bar congestion in the core area of ​​the node, and greatly improves the efficiency of precast beam and column component manufacturing, transportation and installation. Attached Figure Description

[0037] Figure 1This is a structural schematic diagram of the precast prestressed concrete perforated beam frame structure system based on UHPC of the present invention.

[0038] Figure 2 This is a schematic diagram of the reinforcement of a two-span frame structure according to the present invention.

[0039] Figure 3 This is a schematic diagram of the material of a two-span frame structure according to the present invention.

[0040] Figure 4 Detailed construction diagram of the intermediate layer frame edge node of the present invention

[0041] Figure 5 Isometric view of the edge node of the intermediate layer frame of the present invention

[0042] Figure 6 Detailed diagram of node construction in the intermediate layer framework of this invention.

[0043] Figure 7 Axonometric view of the nodes in the intermediate layer frame of this invention. Detailed Implementation

[0044] To make the features, objectives and advantages of the present invention easier to understand, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0045] like Figure 1-7 As shown, the UHPC-connected post-tensioned unbonded precast prestressed concrete perforated beam frame structure system of the present invention includes a precast concrete upper column (1), a precast concrete lower column (2), a post-tensioned unbonded precast prestressed concrete perforated composite beam (3), a UHPC node core area (4), and a composite slab (17).

[0046] The precast concrete upper column (1) is provided with upper longitudinal main reinforcement (5), the precast concrete lower column (2) is provided with lower longitudinal main reinforcement (6), the post-tensioned unbonded precast prestressed concrete perforated composite beam (3) is provided with precast concrete perforated beam (7) and beam composite layer (8) and post-tensioned unbonded prestressed tendons (9), the bottom of the precast concrete perforated beam (7) is provided with ordinary steel bars (10), the beam composite layer (8) is provided with top continuous steel bars (11), and the composite slab (17) is composed of precast concrete slab (18) and slab composite layer (19) poured on the slab;

[0047] The upper longitudinal main reinforcement (5) extends out of the bottom surface of the precast upper column (1) and is directly anchored in the core area (4) of the UHPC node; the lower longitudinal main reinforcement (6) extends out of the top surface of the precast lower column (2) and is directly anchored in the core area (4) of the UHPC node; the ordinary steel reinforcement (10) extends out of the end face of the precast concrete perforated beam (7) and is directly anchored in the core area (4) of the UHPC node.

[0048] The unbonded prestressing tendon (9) includes straight, broken, or curved prestressing tendons;

[0049] Before pouring the beam composite layer (8), slab composite layer (19), and UHPC node core area (4), the post-tensioned unbonded precast prestressed concrete perforated composite beam (3) is constructed according to the force transmission mode adapted to the ordinary concrete perforated simply supported beam and support setup. After pouring the node core area (4), beam composite layer (8), and slab composite layer (19), the concrete strength of the node and composite layer reaches the design requirements, and the unbonded prestressing tendons (9) are tensioned. After tensioning, the supports are removed, and the beam is constructed according to the frame beam setup. Construction stage verification; The upper chord section of the post-tensioned unbonded precast prestressed concrete perforated composite beam is different before and after the casting of the beam composite layer, slab composite layer and UHPC node core area, and the stress state is also different. Construction verification should be carried out on the upper and lower chords at the perforation of the precast concrete perforated beam; After the prestress is established, the construction verification and normal service limit state verification of the unbonded prestressed tendon (9) are calculated based on the effective prestress. When performing the ultimate limit state verification, the stress increment should be considered.

[0050] The post-tensioned unbonded precast prestressed concrete perforated composite beam (3) is composed of a precast concrete perforated beam (7), a beam composite layer (8), and post-tensioned unbonded prestressing tendons (9); the composite slab (17) is composed of a precast concrete slab (18) and a slab composite layer (19) cast on the slab.

[0051] The post-tensioned unbonded prestressed tendon (9) is embedded in the precast concrete perforated beam (7) component and passes through the core area (4) of the UHPC node and extends beyond the core area (4) of the UHPC node at both ends. It is fixed with a clamp (15) and an anchor (16) at both ends respectively, with one end set on the outside of the column and the other end set in the beam composite layer.

[0052] The bottom surface of the precast concrete upper column (1), the top surface of the precast concrete lower column (2), and the end face of the post-tensioned unbonded precast prestressed concrete perforated composite beam (3) are all provided with recessed grooves.

[0053] The precast concrete upper column (1) is fixed in the corresponding position by a reliable support (12);

[0054] The stirrups (13) in the precast concrete upper column (1), precast concrete lower column (2), and post-tensioned unbonded precast prestressed concrete perforated composite beam (3) are divided into a dense zone and an undeniable zone. The stirrups (14) in the core area (4) of the UHPC node are arranged according to the design requirements. The shear bearing capacity of the core area is calculated according to the model of the inclined compression bar and truss. The steel fibers in the UHPC are considered to be equivalent to horizontal stirrups and vertical longitudinal bars, and their contribution to the shear resistance of the core area of ​​the node is considered. At the same time, the beneficial contribution of unbonded prestressed tendons to the shear resistance of the node is also considered.

[0055] The top surfaces of the precast concrete perforated beam (7) and the precast concrete slab (18) are provided with a rough surface layer.

[0056] The seismic design of this system includes the following steps:

[0057] Step 1: Design beams and columns according to existing specifications and invention patents;

[0058] Step 2: Verify the strength of the upper and lower chords at the opening of the precast concrete perforated beam before casting the beam composite layer, slab composite layer and UHPC node core area of ​​the precast prestressed concrete perforated composite beam.

[0059] Step 3: The opening position in the precast prestressed concrete perforated composite beam should be located in the middle 1 / 3 section as much as possible. When it is located in the end 1 / 3 section of the beam, the distance from the edge of the hole near the node to the inner edge of the node should be greater than 1.5 times the beam height.

[0060] A UHPC-connected post-tensioned unbonded precast prestressed concrete perforated beam frame structure system, characterized by comprising the following steps:

[0061] Step 1: Construct precast concrete lower column (2), precast concrete upper column (1), precast concrete perforated beam (7), and precast concrete slab (18); among them, the longitudinal reinforcement of the precast concrete lower column (2) and precast concrete upper column (1) extending into the core area of ​​the node (4) needs to reserve sufficient anchorage length; the ordinary steel bars (10) extending from the precast concrete perforated beam (7) need to be anchored into the core area of ​​the node (4) with sufficient anchorage length; when constructing the precast concrete beam (7), the prestressed tendons (9) are pre-embedded in the design position and sufficient length is reserved at both ends;

[0062] Step 2: After the precast components have been cured, hoist the precast concrete lower column (2) and install it on the foundation, and install a sufficient number of stirrups (14) on the longitudinal main reinforcement (6) extending from the lower column (2);

[0063] Step 3: Hoist the precast concrete perforated beam (7) to the top surface of the precast concrete lower column (2), so that the bottom surface of the precast concrete perforated beam (7) is flush with the top surface of the precast concrete lower column (2), and place the end of the precast concrete perforated beam (7) on the precast concrete lower column (2) and fix it with a support; wherein, the ordinary steel bars (10) extending from the precast concrete perforated beams (7) on both sides are reasonably avoided and directly anchored in the core area of ​​the node according to the structural requirements;

[0064] Step 4: Hoist the precast concrete upper column (1) directly above the precast concrete lower column (2), and fix the precast concrete upper column (1) in the corresponding position with a reliable support (12). At this time, tie the stirrups (14) installed in step 2 together with the column longitudinal reinforcement. The longitudinal reinforcements extending from the precast concrete upper and lower columns are reasonably avoided in the core area of ​​the node and are directly anchored.

[0065] Step 5: Pass the top continuous steel bar (11) through the stirrup (13) reserved in the beam composite layer area and the node core area (4) and tie it. Then tie the prestressed tendons (9) embedded and extended in the precast concrete perforated beam in the node core area according to the design position. Then pour the UHPC node core area (4) and set the formwork so that the UHPC will not enter the beam composite layer (8).

[0066] Step 6: After the core area (4) of the UHPC node has been cured to a sufficient strength, the precast concrete slab (or composite slab, double T slab, secondary beam) (18) is hoisted onto the precast concrete perforated beam (7) and fixed.

[0067] Step 7: Pour the beam composite layer (8) and slab composite layer (19);

[0068] Step 8: After the concrete of the beam composite layer (8) and slab composite layer (19) has been cured to sufficient strength, tension the unbonded prestressed tendons (9);

[0069] Step 9: Repeat the above production process to complete the unbonded prestressed concrete perforated beam frame structure system.

[0070] The above description is merely an exemplary description of the present invention. Obviously, the specific implementation of the present invention is not limited to the above-described manner. That is, the description is not restrictive. Without departing from the inventive concept and technical solution of the present invention, the present invention can be easily improved, changed or replaced in various ways, and all such improvements and changes fall within the protection scope of the present invention.

Claims

1. A UHPC-connected post-tensioned unbonded precast prestressed concrete perforated beam frame structure system, comprising a precast concrete upper column (1), a precast concrete lower column (2), a post-tensioned unbonded precast prestressed concrete perforated composite beam (3), a UHPC node core area (4), and a composite slab (17). Its features are, The precast concrete upper column (1) is provided with upper longitudinal main reinforcement (5), the precast concrete lower column (2) is provided with lower longitudinal main reinforcement (6), the post-tensioned unbonded precast prestressed concrete perforated composite beam (3) is provided with precast concrete perforated beam (7), beam composite layer (8) and post-tensioned unbonded prestressed tendons (9), the bottom of the precast concrete perforated beam (7) is provided with ordinary steel bars (10), and hanging bars (20) and steel mesh (21) are provided around the opening. The steel mesh is welded steel mesh. The beam composite layer (8) is provided with top continuous steel bars (11). The composite slab (17) is composed of precast concrete slab (18) and slab composite layer (19) poured on the slab. The upper longitudinal main reinforcement (5) extends out of the bottom surface of the precast upper column (1) and is directly anchored in the core area (4) of the UHPC node; the lower longitudinal main reinforcement (6) extends out of the top surface of the precast lower column (2) and is directly anchored in the core area (4) of the UHPC node; the ordinary steel reinforcement (10) extends out of the end face of the precast concrete perforated beam (7) and is directly anchored in the core area (4) of the UHPC node. The unbonded prestressing tendon (9) includes straight, broken, or curved prestressing tendons; Before pouring the beam composite layer (8), slab composite layer (19), and UHPC node core area (4), the post-tensioned unbonded precast prestressed concrete perforated composite beam (3) is constructed according to the force transmission mode adapted to the ordinary concrete perforated simply supported beam and support setup. After pouring the node core area (4), beam composite layer (8), and slab composite layer (19), the concrete strength of the node and composite layer reaches the design requirements, and the unbonded prestressing tendons (9) are tensioned. After tensioning, the supports are removed, and the beam is constructed according to the frame beam setup. Construction stage verification; The upper chord section of the post-tensioned unbonded precast prestressed concrete perforated composite beam is different before and after the casting of the beam composite layer, slab composite layer and UHPC node core area, and the stress state is also different. Construction verification should be carried out on the upper and lower chords at the perforation of the precast concrete perforated beam; After the prestress is established, the construction verification and normal service limit state verification of the unbonded prestressed tendon (9) are calculated based on the effective prestress. When performing the ultimate limit state verification, the stress increment should be considered. The post-tensioned unbonded prestressed tendon (9) is embedded in the precast concrete perforated beam (7) component and passes through the core area (4) of the UHPC node and extends beyond the core area (4) of the UHPC node at both ends. It is fixed with a clamp (15) and an anchor (16) at both ends respectively, with one end set on the outside of the column and the other end set in the beam composite layer. The core areas of the edge nodes, middle nodes and corner nodes of the post-tensioned unbonded precast prestressed concrete perforated beam frame structure system are all UHPC node core areas (4); The stirrups in the core area (4) of the UHPC node are arranged according to the design requirements. The shear bearing capacity calculation of the core area considers the steel fibers in the UHPC as equivalent to horizontal stirrups and vertical longitudinal bars, and considers their contribution to the shear resistance of the core area of ​​the node. At the same time, the beneficial contribution of unbonded prestressed tendons to the shear resistance of the core area of ​​the node is also considered. The construction method of the post-tensioned unbonded precast prestressed concrete perforated beam frame structure system includes: The end of the precast concrete perforated beam (7) is placed on the precast concrete lower column (2), and the precast concrete upper column (1) is hoisted to the top of the precast concrete lower column (2). The area enclosed between the precast concrete perforated beam and the precast concrete lower and upper columns is the core area of ​​the UHPC node.

2. The UHPC-connected post-tensioned unbonded precast prestressed concrete perforated beam frame structure system according to claim 1, characterized in that, The post-tensioned unbonded precast prestressed concrete perforated composite beam (3) consists of a precast concrete perforated beam (7), a beam composite layer (8), and post-tensioned unbonded prestressing tendons (9); the composite slab (17) consists of a precast concrete slab (18) and a slab composite layer (19) cast on the slab.

3. The UHPC-connected post-tensioned unbonded precast prestressed concrete perforated beam frame structure system according to claim 1, characterized in that, The bottom surface of the precast concrete upper column (1), the top surface of the precast concrete lower column (2), and the end face of the post-tensioned unbonded precast prestressed concrete perforated composite beam (3) are all provided with recessed grooves.

4. The UHPC-connected post-tensioned unbonded precast prestressed concrete perforated beam frame structure system according to claim 1, characterized in that, The stirrups in the precast concrete upper column (1), precast concrete lower column (2), and post-tensioned unbonded precast prestressed concrete perforated composite beam (3) are divided into a dense zone and an undense zone.

5. The UHPC-connected post-tensioned unbonded precast prestressed concrete perforated beam frame structure system according to claim 1, characterized in that, The top surfaces of the precast concrete perforated beam (7) and the precast concrete slab (18) are provided with a rough surface layer.

6. A design method for a UHPC-connected post-tensioned unbonded prestressed concrete perforated beam frame structure system according to claim 1, characterized in that: The location of the opening in the beam should be in the middle 1 / 3 section as much as possible. When it is located in the end 1 / 3 section of the beam, the distance from the edge of the opening near the node to the inner edge of the node should be greater than 1.5 times the beam height.

7. The construction method of the UHPC-connected post-tensioned unbonded precast prestressed concrete perforated beam frame structure system according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Construct precast concrete lower column (2), precast concrete upper column (1), precast concrete perforated beam (7), and precast concrete slab (18); among them, the longitudinal reinforcement of the precast concrete lower column (2) and precast concrete upper column (1) extending into the core area of ​​the node (4) needs to reserve sufficient anchorage length; the ordinary steel bars (10) extending from the precast concrete perforated beam (7) need to be anchored into the core area of ​​the node (4) with sufficient anchorage length; when constructing the precast concrete perforated beam (7), the prestressed tendons (9) are pre-embedded in the design position, and sufficient length is reserved at both ends; Step 2: After the precast components have been cured, hoist the precast concrete lower column (2) and install it on the foundation, and install a sufficient number of stirrups on the longitudinal main reinforcement (6) extending from the lower column (2); Step 3: Hoist the precast concrete perforated beam (7) to the top surface of the precast concrete lower column (2), so that the bottom surface of the precast concrete perforated beam (7) is flush with the top surface of the precast concrete lower column (2), and place the end of the precast concrete perforated beam (7) on the precast concrete lower column (2) and fix it with a support; wherein, the ordinary steel bars (10) extending from the precast concrete perforated beams (7) on both sides are reasonably avoided and directly anchored in the core area of ​​the node according to the structural requirements; Step 4: Hoist the precast concrete upper column (1) directly above the precast concrete lower column (2), and fix the precast concrete upper column (1) in the corresponding position with a reliable support (12). At this time, tie the stirrups installed in step 2 together with the column longitudinal reinforcement. The longitudinal reinforcements extending from the precast concrete upper and lower columns should be reasonably avoided in the core area of ​​the node and directly anchored. Step 5: Pass the top continuous steel bar (11) through the stirrups reserved in the beam composite layer area and the node core area (4) and tie it. Then tie the prestressed tendons (9) embedded and extended in the precast concrete perforated beam (7) in the node core area according to the design position. Then pour the UHPC node core area (4) and set the template so that the UHPC will not enter the beam composite layer (8). Step 6: After the core area (4) of the UHPC node has been cured to a sufficient strength, the precast concrete slab, composite slab, double T slab or secondary beam is hoisted onto the precast concrete perforated beam (7) and fixed. Step 7: Pour the beam composite layer (8) and slab composite layer (19); Step 8: After the concrete of the beam composite layer (8) and slab composite layer (19) has been cured to sufficient strength, tension the unbonded prestressed tendons (9); Step 9: Repeat the above production process to complete the unbonded prestressed concrete perforated beam frame structure system.

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