A precast concrete frame structure system with UHPC connection and its design and construction method

Abstract

This invention discloses a precast concrete frame structure system with UHPC (Ultra-High-Pressure Polymer) connection, including precast concrete upper columns, precast concrete lower columns, precast concrete composite beams, UHPC node core areas, and composite slabs. The upper longitudinal main reinforcement extends from the bottom surface of the precast upper column and is directly anchored within the UHPC node core area; the lower longitudinal main reinforcement extends from the top surface of the precast lower column and is directly anchored within the UHPC node core area; and ordinary steel bars extend from the end face of the precast concrete beam and are directly anchored or bent and 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 used in the node core area, avoids reinforcement congestion in the node core area, and improves the seismic performance of the overall frame structure. The use of UHPC in the node core area truly realizes the design principle of strong column-weak beam and strong node-weak component.

Description

Technical Field

[0001] This invention relates to the field of prefabricated building construction technology, and more specifically, to a prefabricated concrete frame structure system with UHPC connection 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, UHPC (Ultra High Performance Concrete) materials have been introduced into precast structures.

[0004] UHPC possesses excellent bonding properties, significantly reducing the anchorage length of reinforcing bars. 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, ensuring the implementation of the design principles of strong joints and weak members, and strong columns and weak beams, while also ensuring the formation of plastic hinges at beam ends for energy dissipation. Applying UHPC to the joint core area to form a precast frame structure, and conducting in-depth research on this structure, will facilitate the further promotion and application of precast concrete frame structures. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies and, by leveraging the superior performance of UHPC (Ultra-High-Pressure Polymer), propose a precast concrete frame structure system with UHPC connections, along with its design and construction methods. This system combines the advantages of prefabricated and composite structures, and utilizes high-performance UHPC materials to improve the seismic performance of precast concrete frame structures.

[0006] 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. The number of stirrups in the node core area can be significantly reduced, making it easier to meet the seismic design 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 a very short lap length, thus greatly saving the fabrication time of precast components and on-site installation time. Therefore, the UHPC-connected precast concrete frame structure system and its construction method proposed in this invention are in line with my country's green development strategy for building industrialization.

[0007] The technical problem solved by this invention can be achieved by the following technical solutions:

[0008] A precast concrete frame structure system with UHPC connection includes precast concrete upper columns, precast concrete lower columns, precast concrete composite beams, UHPC node core area and composite slab;

[0009] The precast concrete upper column is provided with upper longitudinal main reinforcement, the precast concrete lower column is provided with lower longitudinal main reinforcement, the precast concrete composite beam is provided with precast concrete beam and beam composite layer, the precast concrete beam is provided with ordinary steel bars, the beam composite layer is provided with top continuous steel bars, and the composite slab is composed of precast concrete slab and slab composite layer poured on the slab.

[0010] 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 bar extends out of the end face of the precast concrete beam and is directly anchored or bent and anchored in the core area of ​​the UHPC node.

[0011] The precast concrete composite beam can also be a fully precast concrete beam.

[0012] Furthermore, the precast concrete composite beam consists of a precast concrete beam and a beam composite layer; the composite slab consists of a precast concrete slab and a slab composite layer cast on the slab.

[0013] Furthermore, the bottom surface of the precast concrete upper column, the top surface of the precast concrete lower column, and the end face of the precast concrete composite beam are all provided with recessed grooves (U-shaped grooves can also be provided at the beam ends, and structural shear reinforcement can be provided if necessary).

[0014] Furthermore, the precast concrete upper column is fixed in the corresponding position using reliable supports.

[0015] Furthermore, the stirrups in the precast concrete upper column, precast concrete lower column, and precast concrete composite beam are divided into a dense zone and a non-dense zone. The stirrups in the core area of ​​the UHPC node are arranged according to the 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.

[0016] Furthermore, the top surface of the precast concrete beam and the precast concrete slab is provided with a rough surface layer.

[0017] This invention also provides a design method for the system, comprising the following steps:

[0018] Step 1: Design beams and columns according to existing specifications and invention patents;

[0019] Step 2: The seismic design of the joints should be carried out according to the following method, calculating the horizontal shear capacity V of the joints. jh :

[0020] The shear capacity of frame beam-column joints shall meet the following requirements:

[0021]

[0022] V jh =V sh +V ch +V fh

[0023] V sh =α·A sjh ·f yj

[0024]

[0025]

[0026] V fh =ηλ f h b b c

[0027]

[0028] In the formula: A sjh —Area of ​​stirrups in the core area of ​​the node;

[0029] f yj —Design value of the yield strength of the stirrups in the core area of ​​the node;

[0030] b j — Node effective width;

[0031] hc —Column height;

[0032] A sb —The sum of the areas of the top and bottom longitudinal reinforcement bars of the beam;

[0033] b b —Liang Kuan;

[0034] h b —Liang Gao;

[0035] f c —Design value of axial compressive strength of concrete;

[0036] η—Effective coefficient of UHPC steel fiber;

[0037] l—Length of UHPC steel fibers;

[0038] d—Diameter of UHPC steel fibers;

[0039] V f —UHPC steel fiber volume content;

[0040] Step 3: At the intermediate nodes of the frame's intermediate floors, the upper longitudinal reinforcement of the frame beams should penetrate through the intermediate nodes; the diameter of each longitudinal reinforcement beam penetrating the central column, for seismic grades I, II, and III, when the column has a rectangular cross-section, should not exceed the smaller of 1 / 18 of the column's cross-sectional dimension in that direction and x; x is calculated using the following formula:

[0041]

[0042] In the formula: f y — This represents the design value of the yield strength of the longitudinal reinforcement bars of the beam that run through the central column.

[0043] A construction method for a precast concrete frame structure system with UHPC connection includes the following steps:

[0044] Step 1: Construct precast concrete lower columns, precast concrete upper columns, precast concrete 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 beams and anchoring them into the core area of ​​the node.

[0045] Step 2: After the precast components are made, hoist the precast concrete lower column and install it on the foundation, and then install an appropriate number of stirrups on the extended longitudinal main bars;

[0046] Step 3: Hoist the precast concrete beam to the top of the precast concrete column, so that the bottom surface of the precast concrete beam is flush with the top surface of the precast concrete column, and place the end of the precast concrete beam on the precast concrete column and fix it with supports; wherein, the reinforcing bars extending from the precast concrete beams on both sides should be reasonably avoided in the core area of ​​the node and directly anchored.

[0047] Step 4: Hoist the precast concrete upper column to the top of the precast concrete lower column, fix the precast concrete upper column in the corresponding position with reliable supports, and tie the stirrups installed in Step 2; wherein, the protruding steel bars of the precast concrete upper and lower columns should be reasonably avoided in the core area of ​​the node and directly anchored.

[0048] Step 5: Pass the top continuous steel bar through the pre-reserved stirrups and the core area of ​​the node in the composite layer and tie it. Then pour the core area of ​​the UHPC node and set the formwork so that the UHPC will not enter the composite layer of the beam.

[0049] Step 6: Hoist the precast concrete slab, composite slab, double T slab, or secondary beam onto the precast concrete beam and secure it.

[0050] Step 7: Pour the beam composite layer and slab composite layer;

[0051] Step 8: Repeat the above production process to complete the precast concrete frame structure system.

[0052] Compared with the prior art, the advantages of the present invention are as follows:

[0053] This invention utilizes high-performance UHPC material, applying it to the core area of ​​joints to achieve reliable anchorage of precast beam-column components. This not only enhances the load-bearing capacity and seismic performance of the joints but also significantly reduces the anchorage length of the reinforcing bars and the amount of stirrups used in the core area, thus avoiding congestion of the reinforcing bars and greatly improving the efficiency of fabrication, transportation, and installation of precast beam-column components. The use of UHPC in the core area of ​​the joints enables the frame structure to achieve plastic hinges at the beam ends for energy dissipation during earthquakes, realizing the design principle of strong joints and weak components, and strong columns and weak beams. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the precast concrete frame structure system with UHPC connection according to the present invention.

[0055] Figure 2 This is a schematic diagram of the reinforcement of a two-span frame structure according to the present invention.

[0056] Figure 3 This is a schematic diagram of the material of a two-span frame structure according to the present invention.

[0057] Figure 4Detailed construction diagram of the intermediate layer frame edge node of the present invention

[0058] Figure 5 Isometric view of the edge node of the intermediate layer frame of the present invention

[0059] Figure 6 Detailed diagram of node construction in the intermediate layer framework of this invention.

[0060] Figure 7 Axonometric view of the nodes in the intermediate layer frame of this invention. Detailed Implementation

[0061] 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.

[0062] like Figure 1-7 As shown, the precast concrete frame structure system with UHPC connection according to the present invention includes a precast concrete upper column (1), a precast concrete lower column (2), a precast concrete composite beam (3), a UHPC node core area (4), and a composite slab (5).

[0063] The precast concrete upper column (1) is provided with upper longitudinal main reinforcement (6), the precast concrete lower column (2) is provided with lower longitudinal main reinforcement (7), the precast concrete composite beam (3) is provided with precast concrete beam (8) and beam composite layer (9), the precast concrete beam (8) is provided with ordinary steel reinforcement (10), the beam composite layer (9) is provided with top continuous steel reinforcement (11), and the composite slab (5) is composed of precast concrete slab (12) and slab composite layer (13) cast on the slab;

[0064] The upper longitudinal main reinforcement (6) 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 (7) 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 beam (8) and is directly anchored or bent and anchored in the core area (4) of the UHPC node.

[0065] The precast concrete composite beam (3) can also be a fully precast concrete beam.

[0066] The precast concrete composite beam (3) is composed of a precast concrete beam (8) and a beam composite layer (9); the composite slab (5) is composed of a precast concrete slab (12) and a slab composite layer (13) cast on the slab.

[0067] 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 precast concrete composite beam (3) are all provided with recessed grooves (U-shaped grooves can also be provided at the beam ends, and structural shear reinforcement can be provided if necessary).

[0068] The precast concrete upper column (1) is fixed in the corresponding position by a reliable support (14).

[0069] The stirrups (15) in the precast concrete upper column (1), precast concrete lower column (2), and precast concrete composite beam (3) are divided into a dense zone and an undense zone. The stirrups (16) 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 softened tension-compression bar model. 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.

[0070] The top surfaces of the precast concrete beam (8) and the precast concrete slab (12) are provided with a rough surface layer.

[0071] The seismic design of this system includes the following steps:

[0072] Step 1: Design beams and columns according to existing specifications and invention patents;

[0073] Step 2: The seismic design of its nodes should be carried out according to the following method: Calculate the horizontal shear capacity V of the node. jh ;

[0074] Step 3: The diameter of each longitudinal steel bar in the beam that runs through the central column should not be greater than the smaller of 1 / 18 of the column's cross-sectional dimension in that direction and x.

[0075] A precast concrete frame structure system with UHPC connection, characterized by comprising the following steps:

[0076] Step 1: Construct precast concrete lower column (2), precast concrete upper column (1), precast concrete beam (8), and precast concrete slab (12); among them, the longitudinal reinforcement of the precast concrete lower column (2) and precast concrete upper column (1) extending into the core area (4) of the node needs to reserve sufficient anchorage length; the ordinary steel bars extending from the precast concrete beam (8) into the core area (4) of the node need to reserve sufficient anchorage length;

[0077] Step 2: After the precast components are made, hoist the precast concrete lower column (2) and install it on the foundation, and then install an appropriate number of stirrups (16) on the extended longitudinal main reinforcement (7);

[0078] Step 3: Hoist the precast concrete beam (8) to the top surface of the precast concrete lower column (2), so that the bottom surface of the precast concrete beam (8) is flush with the top surface of the precast concrete lower column (2), and place the end of the precast concrete beam (8) on the precast concrete lower column (2) and fix it with a support; wherein, the steel bars (10) extending from the precast concrete beams (8) on both sides are reasonably avoided in the core area of ​​the node and directly anchored;

[0079] Step 4: Hoist the precast concrete upper column (1) directly above the precast concrete lower column (2), fix the precast concrete upper column (1) in the corresponding position with a reliable support (14), and tie the stirrups (16) installed in Step 2; wherein, the protruding steel bars of the precast concrete upper and lower columns are reasonably avoided in the core area of ​​the node and are directly anchored.

[0080] Step 5: Pass the top continuous steel bar (11) through the pre-reserved stirrups (15) and the core area of ​​the node (4) in the composite layer and tie them. Then pour the core area of ​​the UHPC node (4) and set the formwork so that the UHPC will not enter the composite layer (9) of the beam.

[0081] Step 6: Hoist the precast concrete slab (or composite slab, double T slab, secondary beam) (12) onto the precast concrete beam (8) and fix it in place;

[0082] Step 7: Pour the beam composite layer (9) and slab composite layer (13);

[0083] Step 8: Repeat the above production process to complete the precast concrete frame structure system.

[0084] 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 precast concrete frame structure system with UHPC connection, comprising a precast concrete upper column (1), a precast concrete lower column (2), a precast concrete composite beam (3), a UHPC node core area (4), and a composite slab (5); Its features are, The precast concrete upper column (1) is provided with upper longitudinal main reinforcement (6), the precast concrete lower column (2) is provided with lower longitudinal main reinforcement (7), the precast concrete composite beam (3) is provided with precast concrete beam (8) and beam composite layer (9), the precast concrete beam (8) is provided with ordinary steel reinforcement (10), the beam composite layer (9) is provided with top continuous steel reinforcement (11), and the composite slab (5) is composed of precast concrete slab (12) and slab composite layer (13) cast on the slab; The upper longitudinal main reinforcement (6) 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 (7) 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 beam (8) and is directly anchored or bent and anchored in the core area (4) of the UHPC node. The precast concrete composite beam (3) can also be a fully precast concrete beam; The core areas of the edge nodes, middle nodes and corner nodes of the precast concrete 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. The construction method of the precast concrete frame structure system includes the following steps: The end of the precast concrete beam (8) 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 beam and the precast concrete lower and upper columns is the core area of ​​the UHPC node.

2. The precast concrete frame structure system with UHPC connection according to claim 1, characterized in that, The precast concrete composite beam (3) consists of a precast concrete beam (8) and a beam composite layer (9); the composite slab (5) consists of a precast concrete slab (12) and a slab composite layer (13) cast on the slab.

3. The precast concrete frame structure system with UHPC connection 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 precast concrete composite beam (3) are all provided with recessed grooves.

4. The precast concrete frame structure system with UHPC connection according to claim 1, characterized in that, The stirrups in the precast concrete upper column (1), precast concrete lower column (2), and precast concrete composite beam (3) are divided into a dense zone and a non-dense zone.

5. The precast concrete frame structure system with UHPC connection according to claim 1, characterized in that, The top surfaces of the precast concrete beam (8) and the precast concrete slab (12) are provided with a rough surface layer.

6. A construction method for a precast concrete frame structure system with UHPC connection 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 beam (8), and precast concrete slab (12); among them, the longitudinal reinforcement of the precast concrete lower column (2) and precast concrete upper column (1) extending into the core area (4) of the node needs to reserve sufficient anchorage length; the ordinary steel bars extending from the precast concrete beam (8) into the core area (4) of the node need to reserve sufficient anchorage length; Step 2: After the precast components are made, hoist the precast concrete lower column (2) and install it on the foundation, and then install an appropriate number of stirrups on the extended longitudinal main reinforcement (7); Step 3: Hoist the precast concrete beam (8) to the top surface of the precast concrete lower column (2), so that the bottom surface of the precast concrete beam (8) is flush with the top surface of the precast concrete lower column (2), and place the end of the precast concrete beam (8) on the precast concrete lower column (2) and fix it with simple support; wherein, the steel bars (10) extending from the precast concrete beams (8) on both sides are reasonably avoided in the core area of ​​the node and directly anchored; Step 4: Hoist the precast concrete upper column (1) directly above the precast concrete lower column (2), fix the precast concrete upper column (1) in the corresponding position with a reliable support (14), and tie the stirrups installed in Step 2; wherein, the protruding steel bars of the precast concrete upper and lower columns are reasonably avoided in the core area of ​​the node and are directly anchored. Step 5: Pass the top continuous steel bar (11) through the pre-reserved stirrups and node core area (4) of the composite layer and tie it. Then pour the UHPC node core area (4) and set the formwork so that the UHPC will not enter the beam composite layer (9). Step 6: Hoist the precast concrete slab, composite slab, double T slab or secondary beam onto the precast concrete beam (8) and fix it in place; Step 7: Pour the beam composite layer (9) and slab composite layer (13); Step 8: Repeat the above production process to complete the precast concrete frame structure system.

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