A double post-tensioning prefabricated prestressed concrete frame structure system connected by UHPC and a design and construction method thereof

Abstract

The application discloses a kind of UHPC connection's double post-tensioning prefabricated prestressed concrete frame structure system, including prefabricated concrete upper column, prefabricated concrete lower column, double post-tensioning prefabricated prestressed concrete composite beam, UHPC node core area and composite slab.The upper longitudinal main reinforcement, lower longitudinal main reinforcement, ordinary steel and post-tensioning prestressed tendon are directly anchored in UHPC node core area.The structure system is not only convenient and fast in field construction, improves component installation efficiency, but also can greatly reduce the anchoring length of steel bar, greatly reduce the amount of stirrup in node core area, avoid crowded steel bar in node core area, and reduce the cross-sectional height of component, reduce self weight, improve component crack resistance and self-recovery performance, thereby improve the seismic performance of overall frame structure.Double post-tensioning design can be reasonably designed according to different span, different load, different seismic intensity and other requirements, reduce cost, meet the use requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of prefabricated prestressed assembly type building construction, in particular to a UHPC connected double post-tensioning prefabricated prestressed concrete frame structure system and a design and construction method thereof. BACKGROUND

[0002] The construction efficiency of cast-in-place structures is low, and the energy loss is high, and many limitations, which gradually cannot meet the development requirements of building industrialization. Prefabricated assembly type buildings have become the development direction of building industrialization due to their advantages of fast construction speed, factory production of components, reduction of on-site wet work and environmental pollution. After years of development and promotion, prefabricated assembly type concrete structures have been widely researched and used.

[0003] Prefabricated assembly type concrete frame structure refers to the structure in which beam and column components are prefabricated in a prefabrication plant and transported to the construction site for connection to form an overall structure. Compared with cast-in-place concrete structures, it has the advantages of fast construction speed, easy guarantee of component quality, good quality, less environmental pollution, saving of labor cost, and saving of a large number of formwork and support, etc., and is a structure form with very broad prospects. For wet connection assembly type concrete frame structures, the joint construction form which is easy to construct and effectively guarantees the integrity is the key to the popularization and application. However, from the past earthquake disasters, the assembly type structure is severely damaged in the earthquake, and it is difficult to achieve the same seismic performance as the cast-in-place structure. In order to improve the integrity and reliability of the assembly type concrete frame joint connection and achieve or exceed the seismic performance of the cast-in-place concrete structure, prestressing technology and UHPC (Ultra High Performance Concrete, ultra high performance concrete) materials are introduced into the assembly type structure.

[0004] Double post-tensioning prefabricated concrete structure is a structure formed by assembling prefabricated ordinary concrete components and prefabricated post-tensioning components together and working together through tensioning of prestressed reinforcement, which has the characteristics of post-tensioning concrete structure and assembly type structure. The internal stress generated by prestress in the concrete section can partially or completely offset the stress in the section under the use load, delay the occurrence of cracks and improve the stiffness of the component. When unloaded, the cracks can be partially or completely closed, and the elastic recovery performance of the structure is good. At the same time, the prestressed concrete can fully utilize the material strength of the prestressed reinforcement and the concrete, and reduce the self weight of the structure. And the application of prestress helps to improve the performance and integrity of the assembly type structure, and promotes the application of the assembly type structure in large-span and heavy-load structures.

[0005] UHPC has excellent bonding performance, which can greatly reduce the anchorage length of steel bars and steel strands; it has high strength, which can reduce the amount of stirrups in the core area of the joint; using UHPC in the core area of the joint can make the structure simple and the overall framework good. The prestressed structure has excellent stress performance, and the application of UHPC in the core area of the joint forms a prefabricated prestressed framework structure. Further research on this structure is beneficial to the further promotion and application of prefabricated prestressed concrete framework structure. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art, combine the excellent performance of UHPC, and propose a UHPC connected double post-tensioning prefabricated prestressed concrete framework structure system and its design and construction method. It combines three traditional structures of post-tensioning prestressed structure, assembly structure and composite structure, and uses UHPC high-performance material, so as to improve the seismic performance of prefabricated assembly concrete framework structure.

[0007] The advantages of the present application mainly lie in the connection technology of prefabricated post-tensioning prestressed concrete beam-column components and the steel bar connection technology between components. In the component connection technology, the beam-column components are connected by UHPC with excellent performance to form the UHPC joint core area, which is more conducive to realizing the seismic fortification requirement of strong joint and weak component, thereby improving the ductility of beam-column joint and further improving the seismic performance of the overall framework structure. In the steel bar connection technology, the steel bars between the beam-column components only need to be simply overlapped, and the overlap length is very small, thereby greatly saving the production time of prefabricated components and the installation time on site. Therefore, the UHPC connected double post-tensioning prefabricated prestressed concrete framework structure system and its construction method proposed by the present application meet the green development strategy of building industrialization in China.

[0008] The technical problems solved by the present application can be realized by the following technical solutions:

[0009] A UHPC connected double post-tensioning prefabricated prestressed concrete framework structure system, comprising a prefabricated concrete upper column, a prefabricated concrete lower column, a double post-tensioning prefabricated prestressed concrete composite beam, a UHPC joint core area and a composite slab.

[0010] The prefabricated concrete upper column is provided with upper longitudinal main reinforcement, the prefabricated concrete lower column is provided with lower longitudinal main reinforcement, the double post-tensioning prefabricated prestressed concrete composite beam is provided with a prefabricated post-tensioning prestressed concrete beam, a beam composite layer and post-tensioning prestressed reinforcement two, the bottom of the prefabricated post-tensioning prestressed concrete beam is provided with ordinary steel bars and post-tensioning prestressed reinforcement one, the beam composite layer is provided with top longitudinal steel bars, and the composite slab is composed of a prefabricated concrete slab and a slab composite layer poured on the slab.

[0011] The upper longitudinal main reinforcement extends out of the bottom surface of the prefabricated upper column and is directly anchored in the UHPC node core area, the lower longitudinal main reinforcement extends out of the top surface of the prefabricated lower column and is directly anchored in the UHPC node core area, and the ordinary steel bars and the post-tensioned prestressed bars extend out of the end surface of the prefabricated post-tensioned prestressed concrete beam and are directly anchored in the UHPC node core area;

[0012] The double post-tensioned prefabricated prestressed concrete composite beam can also be a full prefabricated prestressed concrete beam.

[0013] The post-tensioned prestressed bar one is only tensioned in the prefabricated post-tensioned prestressed concrete beam, and the post-tensioned prestressed bar two is tensioned together with the outside of the column.

[0014] The post-tensioned prestressed bar one and the post-tensioned prestressed bar two include straight-line, broken-line, and curved-line prestressed bars.

[0015] The post-tensioned prestressed bar one and the post-tensioned prestressed bar two are un-bonded, slow-bonded, or bonded prestressed bars.

[0016] When the post-tensioned prestressed bar one is calculated considering the self-weight and construction load in the construction stage, the effective prestress of the post-tensioned prestressed bar one is calculated; when the normal use or the ultimate bearing capacity is calculated, the post-tensioned prestressed bar one is calculated according to the actual bonding condition of the prestressed bar.

[0017] The post-tensioned prestressed bar two can be bonded, partially bonded, un-bonded, or non-bonded in the node core area.

[0018] The double post-tensioned prefabricated prestressed concrete composite beam is calculated as a post-tensioned prestressed concrete simply supported beam before pouring the beam composite layer, the plate composite layer, and the UHPC node core area; after pouring the node core area and the beam composite layer and the plate composite layer, and when the strength of the node and the composite layer concrete reaches the design requirement, the post-tensioned prestressed bar two is tensioned; after the tensioning is completed, the construction stage calculation is performed according to the un-bonded prestressed bar; when the normal use or the ultimate bearing capacity is calculated, the post-tensioned prestressed bar two is calculated according to the actual bonding condition of the prestressed bar; and for the un-bonded part of the post-tensioned prestressed bar two in the node core area, the restoring performance provided by the un-bonded part is considered under the seismic load.

[0019] Further, the double post-tensioned prefabricated prestressed concrete composite beam is composed of a prefabricated post-tensioned prestressed concrete beam, a beam composite layer, and a post-tensioned prestressed bar two; and the composite plate is composed of a prefabricated concrete plate and a plate composite layer poured on the plate.

[0020] Further, the post-tensioned prestressed reinforcement is arranged in the prefabricated post-tensioned prestressed concrete beam component, passes through the UHPC node core area and extends out of the UHPC node core area at both ends, and is fixed with a clamp and an anchor at both ends, respectively, and is arranged outside the column at one end and in the beam composite layer at the other end.

[0021] Further, the bottom surface of the prefabricated concrete upper column, the top surface of the prefabricated concrete lower column and the end surface of the double post-tensioned prefabricated prestressed concrete composite beam are provided with recessed grooves (U-shaped grooves can also be arranged at the beam ends, and constructional shear reinforcement can be arranged if necessary).

[0022] Further, the prefabricated concrete upper column is fixed at the corresponding position by reliable support.

[0023] Further, the stirrups in the prefabricated concrete upper column, the prefabricated concrete lower column and the double post-tensioned prefabricated prestressed concrete composite beam are divided into dense areas and non-dense areas, the stirrups in the UHPC node core area are arranged according to design requirements, the shear bearing capacity of the core area is calculated according to the softened strut-and-tie model, and the steel fibers in the UHPC are equivalent to horizontal stirrups and vertical longitudinal reinforcement, and the contribution of the steel fibers to the shear of the node core area is considered.

[0024] Further, the prefabricated post-tensioned prestressed concrete beam and the top surface of the prefabricated concrete plate are provided with a rough surface layer.

[0025] The application also provides a design method of the system, which comprises the following steps:

[0026] Step 1: the beam and the column are designed according to existing specifications and invention patents;

[0027] Step 2: the seismic design of the node needs to be carried out according to the following method, and the horizontal shear bearing capacity Vjh of the node is calculated:

[0028] The shear bearing capacity of the frame beam-column node should meet the following provisions:

[0029]

[0030] ω h = ρ jh f yh / f c

[0031] ω b = ρ b f yb / f c

[0032] ω v = ρ c f yv / f c

[0033] ρ jh =A jh / (H c b j )

[0034] ρ b =A b / (H b b b )

[0035] ρ c =A jv / (H c b c )

[0036] V fh =ηλ f h b b c

[0037]

[0038] In the formula: γ c γ h γ v —Coefficients for concrete diagonal compression members, horizontal trusses, and vertical trusses

[0039] a c —Height of the compression zone of the column section

[0040] φ—Angle of the diagonal compression member

[0041] H b —Liang Gao

[0042] H c ——Column height

[0043] b b —Liang Kuan

[0044] b c ——Column width

[0045] b j — Node effective width

[0046] f yh f yb f yv —Strength of horizontal stirrups, beam longitudinal reinforcement, and column longitudinal reinforcement in the core area of ​​the node

[0047] f c —Design value of axial compressive strength of concrete

[0048] N pe —Effective prestressing resultant force of post-tensioned prestressing tendon 2(9) acting on the core area of ​​the node

[0049] η - UHPC steel fiber effective coefficient

[0050] l - UHPC steel fiber length

[0051] d - UHPC steel fiber diameter

[0052] V f - UHPC steel fiber volume content.

[0053] Step 3: In the intermediate layer of the frame, the upper longitudinal reinforcement of the frame beam should pass through the intermediate node. The diameter of each beam longitudinal reinforcement passing through the column shall not be greater than the smaller value of 1 / 18 of the column cross-sectional size in that direction and x, x is calculated according to the following formula:

[0054]

[0055] In the formula: - design axial compression ratio.

[0056] A UHPC connected double post-tensioned precast prestressed concrete frame structure system, comprising the following steps:

[0057] Step 1: Make precast concrete lower column, precast concrete upper column, precast post-tensioned prestressed concrete beam, and precast concrete slab; wherein the precast concrete lower column and the precast concrete upper column extend the longitudinal reinforcement to be anchored into the node core area with sufficient anchoring length; when making the post-tensioned prestressed concrete beam, post-tensioned prestressed tendon one and post-tensioned prestressed tendon two are embedded in the beam according to the design position, and sufficient length is reserved at both ends, and then the concrete is poured, and when the concrete is cured to sufficient strength, the post-tensioned prestressed tendon one is tensioned and clamps and anchors are set at both ends; wherein when the post-tensioned prestressed tendon one and the post-tensioned prestressed tendon two are unbounded or slow-bonded prestressed tendons, they are directly embedded in the design position; when the post-tensioned prestressed tendon one (17) and the post-tensioned prestressed tendon two (9) are bonded prestressed tendons, corrugated pipes need to be embedded in the precast concrete beam;

[0058] Step 2: After the precast components are cured, the precast concrete lower column is hoisted and installed on the foundation, and then a proper number of stirrups are installed on the extended longitudinal main reinforcement according to the design requirements;

[0059] Step 3: Hoist the precast post-tensioned prestressed concrete beam to the top surface of the precast concrete lower column, make the bottom surface of the precast post-tensioned prestressed concrete beam flush with the top surface of the precast concrete lower column, make the end of the precast post-tensioned prestressed concrete beam rest on the precast concrete lower column, and fix it with supports, which can also be exempted from support due to the prestressing effect in the beam; wherein the ordinary steel reinforcement of the two side post-tensioned prestressed concrete beams and the node core area are reasonably avoided and directly anchored according to the construction requirements;

[0060] Step 4: hoist the prefabricated concrete upper column to the directly above the prefabricated concrete lower column, fix the prefabricated concrete upper column in the corresponding position with reliable support, at this time, the stirrup and column longitudinal reinforcement installed in step 2 are tied together, wherein the longitudinal reinforcement of the prefabricated concrete upper and lower columns is reasonably avoided in the node core area and directly anchored;

[0061] Step 5: pass the top longitudinal reinforcement through the stirrup reserved in the beam composite layer area and the node core area and tie it well, then tie the post-tensioned prestressed reinforcement two embedded in the post-tensioned prestressed concrete beam and stretched in the node core area according to the design position, when the post-tensioned prestressed reinforcement two is a bonded prestressed reinforcement, a section of bellows pipe is embedded in the node core area to form a whole with the bellows pipe embedded in the post-tensioned prestressed concrete beam, when the post-tensioned prestressed reinforcement two is a non-bonded prestressed reinforcement, a sleeve pipe is needed on the non-bonded part of the node, then pour the UHPC node core area, and set the formwork so that the UHPC does not enter the beam composite layer part;

[0062] Step 6: after the UHPC node core area is cured to sufficient strength, hoist the prefabricated concrete flat plate, composite plate, double T plate or secondary beam to the prefabricated concrete beam and fix it;

[0063] Step 7: pour the beam composite layer and the plate composite layer;

[0064] Step 8: after the beam composite layer and the plate composite layer are cured to sufficient strength, tension the post-tensioned prestressed reinforcement two, when the post-tensioned prestressed reinforcement two is a bonded prestressed reinforcement, the reinforcement is first passed in the bellows pipe and then tensioned, finally, the bellows pipe in the bonded part of the beam and the node is grouted, and the non-bonded part of the node is not grouted;

[0065] Step 9: repeat the above manufacturing process to complete the double post-tensioned prefabricated prestressed concrete frame structure system.

[0066] Compared with the prior art, the application has the advantages that:

[0067] 1. The prefabricated assembly type concrete structure and the post-tensioned prestressed structure are combined together in the application, the advantages of the prefabricated assembly type structure, such as convenient and fast construction, good construction quality, energy saving and environmental protection, are utilized, the post-tensioned common tension prestressed structure is combined to improve the structural performance, reduce the cross section height of the component, reduce the self weight, improve the crack resistance and self recovery of the component, and thus the seismic performance of the overall frame structure is improved. The double post-tensioned design can be reasonably designed according to different span, different load, different seismic intensity and other requirements, the cost is reduced, and the use requirements are met.

[0068] 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 steel strands, and significantly reduce the amount of stirrups used in the core area of ​​the node. This avoids the congestion of steel bars in the core area of ​​the node, and greatly improves the efficiency of the production, transportation and installation of precast beam and column components. Attached Figure Description

[0069] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0070] Figure 1 This is a schematic diagram of the precast prestressed concrete frame structure system based on UHPC of the present invention.

[0071] Figure 2 This is a schematic diagram of the reinforcement of a two-span frame structure according to the present invention.

[0072] Figure 3 This is a schematic diagram of the material of a two-span frame structure according to the present invention.

[0073] Figure 4 This is a detailed diagram of the construction of the edge nodes of the intermediate layer frame of the present invention.

[0074] Figure 5 This is an isometric view of the edge node of the intermediate layer frame of the present invention.

[0075] Figure 6 This is a detailed diagram of the node construction in the intermediate layer framework of the present invention.

[0076] Figure 7 This is an isometric view of the nodes in the intermediate layer framework of the present invention. Detailed Implementation

[0077] 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.

[0078] like Figures 1-7 As shown, the UHPC-connected double-post-tensioned prestressed concrete frame structure system of the present invention includes a precast concrete upper column (1), a precast concrete lower column (2), a double-post-tensioned precast prestressed concrete composite beam (3), a UHPC node core area (4), and a composite slab (18).

[0079] The prefabricated concrete upper column (1) is provided with upper longitudinal main reinforcement (5), the prefabricated concrete lower column (2) is provided with lower longitudinal main reinforcement (6), the double post-tensioning prefabricated prestressed concrete composite beam (3) is provided with prefabricated post-tensioning prestressed concrete beam (7) and beam composite layer (8) and post-tensioning prestressed tendon two (9), the prefabricated post-tensioning prestressed concrete beam (7) bottom is provided with ordinary steel bar (10) and post-tensioning prestressed tendon one (17), the beam composite layer (8) is provided with top longitudinal steel bar (11), and the composite slab (18) is composed of prefabricated concrete slab (19) and slab composite layer (20) poured on the slab;

[0080] The upper longitudinal main reinforcement (5) extends out of the bottom surface of the prefabricated upper column (1) and is directly anchored in the UHPC node core area (4), the lower longitudinal main reinforcement (6) extends out of the top surface of the prefabricated lower column (2) and is directly anchored in the UHPC node core area (4), the ordinary steel bar (10) and the post-tensioning prestressed tendon one (17) extend out of the end surface of the prefabricated post-tensioning prestressed concrete beam (7) and are directly anchored in the UHPC node core area (4);

[0081] The double post-tensioning prefabricated prestressed concrete composite beam (3) can also be a full prefabricated prestressed concrete beam;

[0082] The post-tensioning prestressed tendon one (17) is only tensioned in the prefabricated post-tensioning prestressed concrete beam (7), and the post-tensioning prestressed tendon two (9) is tensioned together with the column outside in the prefabricated post-tensioning prestressed concrete beam (7);

[0083] The post-tensioning prestressed tendon one (17) and the post-tensioning prestressed tendon two (9) include straight line, broken line, and curved prestressed tendon;

[0084] The post-tensioning prestressed tendon one (17) and the post-tensioning prestressed tendon two (9) are unbonded, slow-bonded, or bonded prestressed tendons;

[0085] The post-tensioning prestressed tendon one (17) is calculated for effective prestress when considering self-weight and construction load during the construction stage, and is calculated for actual bonding condition of prestressed tendons when calculating normal use or ultimate bearing capacity, respectively for bonded and unbonded;

[0086] The post-tensioning prestressed tendon two (9) can be bonded, partially bonded, unbonded, or non-bonded in the node core area;

[0087] The double post-tensioned prefabricated prestressed concrete composite beam (3) is calculated according to the post-tensioned concrete simple beam before pouring the beam composite layer (8), the plate composite layer (20) and the UHPC node core area (4), and after pouring the node core area (4) and the beam composite layer (8), the plate composite layer (20), the node and the composite layer concrete strength reaches the design requirement, the post-tensioned prestressed tendon two (9) is tensioned, after the tensioning is completed, the construction stage calculation is carried out according to the un-bonded prestressed tendon; when the normal use or the ultimate bearing capacity is calculated, the post-tensioned prestressed tendon two (9) is calculated according to the actual bonding state of the prestressed tendon respectively according to the bonding and the un-bonding; for the un-bonding part of the post-tensioned prestressed tendon two (9) in the node core area, the restoring performance provided by it is considered under the earthquake load.

[0088] The double post-tensioned prefabricated prestressed concrete composite beam (3) is composed of a prefabricated post-tensioned prestressed concrete beam (7), a beam composite layer (8) and a post-tensioned prestressed tendon two (9); the composite plate (18) is composed of a prefabricated concrete plate (19) and a plate composite layer (20) poured on the plate.

[0089] The post-tensioned prestressed tendon two (9) is arranged in the prefabricated post-tensioned prestressed concrete beam (7) component, passes through the UHPC node core area (4) and extends out of the UHPC node core area (4) at both ends, and clamps (15) and anchors (16) are respectively arranged at both ends, one end is arranged outside the column, and the other end is arranged in the beam composite layer.

[0090] The bottom surface of the prefabricated concrete upper column (1), the top surface of the prefabricated concrete lower column (2) and the end surface of the double post-tensioned prefabricated prestressed concrete composite beam (3) are provided with recesses (U-shaped grooves can also be arranged at the beam end, and constructional shear reinforcement can be arranged if necessary).

[0091] The prefabricated concrete upper column (1) is fixed in the corresponding position by reliable support (12).

[0092] The stirrups (13) in the prefabricated concrete upper column (1), the prefabricated concrete lower column (2) and the double post-tensioned prefabricated prestressed concrete composite beam (3) are divided into dense areas and non-dense areas, the stirrups (14) in the UHPC node core area (4) are arranged according to design requirements, the shear bearing capacity of the core area is calculated according to the softened strut-and-tie model, and the steel fibers in the UHPC are equivalent to horizontal stirrups and vertical longitudinal reinforcement, and the contribution of the steel fibers to the shear resistance of the node core area is considered.

[0093] The top surface of the prefabricated post-tensioned prestressed concrete beam (7) and the prefabricated concrete plate (19) is provided with a rough surface layer.

[0094] The seismic design of the system includes the following steps:

[0095] Step 1: The beam and column are designed according to the existing specification and invention patent;

[0096] Step 2: The seismic design of its node needs to be carried out according to the following method: calculate the horizontal shear capacity Vjh of the node;

[0097] Step 3: The diameter of the longitudinal reinforcement of each beam passing through the middle column should not be greater than 1 / 18 of the smaller value of x and the sectional size of the column in that direction.

[0098] A UHPC connected double post-tensioned precast prestressed concrete frame structure system, characterized in that it comprises the following steps:

[0099] Step 1: Make precast concrete lower column (2), precast concrete upper column (1), precast post-tensioned prestressed concrete beam (7), and precast concrete slab (19); wherein the precast concrete lower column (2) and the precast concrete upper column (1) are anchored into the node core area (4) with sufficient anchorage length; when making the post-tensioned prestressed concrete beam (7), the post-tensioned prestressed tendon one (17) and the post-tensioned prestressed tendon two (9) are embedded in the beam according to the design position, and sufficient length is reserved at both ends, and then the concrete is poured, and when the concrete is cured to sufficient strength, the post-tensioned prestressed tendon one (17) is tensioned and fixtures and anchors are set at both ends; wherein when the post-tensioned prestressed tendon one (17) and the post-tensioned prestressed tendon two (9) are uncoated or slow-coated prestressed tendons, they are directly embedded in the design position; when the post-tensioned prestressed tendon one (17) and the post-tensioned prestressed tendon two (9) are bonded prestressed tendons, corrugated pipes need to be embedded in the precast concrete beam (7);

[0100] Step 2: After the precast components are cured, the precast concrete lower column (2) is hoisted and installed on the foundation, and then a proper number of stirrups (14) are installed on the extended longitudinal main reinforcement (6) according to the design requirements;

[0101] Step 3: Hoist the precast post-tensioned prestressed concrete beam (7) to the top surface of the precast concrete lower column (2), make the bottom surface of the precast post-tensioned prestressed concrete beam (7) flush with the top surface of the precast concrete lower column (2), make the end of the precast post-tensioned prestressed concrete beam (7) rest on the precast concrete lower column (2), and fix it with supports; wherein the ordinary steel bars (10) extending from the two sides of the post-tensioned prestressed concrete beam (7) and the node core area are reasonably avoided and directly anchored according to the construction requirements;

[0102] Step 4: hoist the prefabricated concrete upper column (1) to directly above the prefabricated concrete lower column (2), fix the prefabricated concrete upper column (1) in the corresponding position with reliable support (12), at this time, the stirrup (14) installed in step 2 is tied together with the column longitudinal reinforcement; wherein the longitudinal reinforcement of the prefabricated concrete upper and lower columns is reasonably avoided in the node core area and directly anchored;

[0103] Step 5: pass the top longitudinal reinforcement (11) through the stirrup (13) reserved in the beam composite layer area and the node core area (4) and tie well, then tie the post-tensioned prestressed tendon two (9) embedded in the post-tensioned prestressed concrete beam (7) and extending in the node core area according to the design position, (when the post-tensioned prestressed tendon two (9) is a bonded prestressed tendon, a section of bellows is embedded in the node core area to form a whole with the bellows embedded in the post-tensioned prestressed concrete beam (7); when it is a non-bonding prestressed tendon, a sleeve is needed on the non-bonding part of the node), then pour the UHPC node core area (4) and set the formwork so that the UHPC does not enter the beam composite layer (8) part;

[0104] Step 6: after the UHPC node core area (4) is cured to sufficient strength, hoist the prefabricated concrete slab, composite slab, double-T slab or secondary beam to the prefabricated concrete beam (7) and fix it;

[0105] Step 7: pour the beam composite layer (8) and the slab composite layer (20);

[0106] Step 8: after the beam composite layer (8) and the slab composite layer (20) are cured to sufficient strength, tension the post-tensioned prestressed tendon two (9) (when the post-tensioned prestressed tendon two (9) is a bonded prestressed tendon, first pass the tendon in the bellows and then tension, finally grout in the bellows of the beam and the bonded part of the node, and do not grout for the non-bonding prestressed tendon part of the node);

[0107] Step 9: repeat the above manufacturing process to complete the double post-tensioned prefabricated prestressed concrete frame structure system.

[0108] The above is only an exemplary description of the present application, and it is obvious that the specific implementation of the present application is not limited by the above method. That is, the description is not limiting, and the present application can be easily improved, changed or replaced without departing from the method concept and technical solution of the present application. These improvements and changes are within the scope of protection of the present application.

Claims

1. A UHPC-connected double-post-tensioned prestressed concrete frame structure system, comprising a precast concrete upper column (1), a precast concrete lower column (2), a double-post-tensioned precast prestressed concrete composite beam (3), a UHPC node core area (4), and a composite slab (18); 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 double post-tensioned precast prestressed concrete composite beam (3) is provided with precast post-tensioned prestressed concrete beam (7), beam composite layer (8) and post-tensioned prestressing tendon two (9), the bottom of the precast post-tensioned prestressed concrete beam (7) is provided with ordinary steel bar (10) and post-tensioned prestressing tendon one (17), the beam composite layer (8) is provided with top continuous steel bar (11), and the composite slab (18) is composed of precast concrete slab (19) and slab composite layer (20) 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) and the post-tensioned prestressed tendon (17) extend out of the end face of the precast post-tensioned prestressed concrete beam (7) and are directly anchored in the core area (4) of the UHPC node; The double-post-tensioned prestressed concrete composite beam (3) can also be a fully prestressed concrete beam; The first post-tensioned prestressing tendon (17) is tensioned only inside the precast post-tensioned prestressed concrete beam (7), while the second post-tensioned prestressing tendon (9) is tensioned together inside the precast post-tensioned prestressed concrete beam (7) and outside the column. The first post-tensioned prestressing tendon (17) and the second post-tensioned prestressing tendon (9) include straight, broken, and curved prestressing tendons; The first post-tensioned prestressing tendon (17) and the second post-tensioned prestressing tendon (9) are unbonded, loosely bonded or bonded prestressing tendons; The effective prestress of the post-tensioned prestressing tendon 1 (17) is calculated when considering self-weight and construction load during the construction stage; when performing normal use or ultimate bearing calculation, it is calculated according to the actual bonding condition of the prestressing tendon as bonded and unbonded respectively; the post-tensioned prestressing tendon 2 (9) can be bonded, partially bonded, unbonded, or unbonded in the core area of ​​the node; Before pouring the beam composite layer (8), slab composite layer (20) and UHPC node core area (4), the double post-tensioned prestressed concrete composite beam (3) is constructed as a post-tensioned prestressed concrete simply supported beam. After pouring the node core area (4), beam composite layer (8), and slab composite layer (20), when the concrete strength of the node and composite layer reaches the design requirements, the second post-tensioned prestressing tendon (9) is tensioned. After tensioning, the construction stage is verified as an unbonded prestressing tendon. When performing normal use or ultimate bearing verification, the second post-tensioned prestressing tendon (9) is calculated as bonded and unbonded according to the actual bonding condition of the prestressing tendon. For the unbonded part of the node core area of ​​the second post-tensioned prestressing tendon (9), its recovery performance is considered under seismic load. The second post-tensioned prestressing tendon (9) is set in the precast post-tensioned prestressed concrete beam (7) component, passes through the core area (4) of the UHPC node and extends out of the core area (4) of the UHPC node at both ends. It is fixed with clamps (15) and anchors (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 double post-tensioned precast prestressed 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 double-post-tensioned prestressed concrete frame structure system includes: The end of the precast post-tensioned prestressed concrete 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 post-tensioned prestressed concrete beam and the precast concrete lower and upper columns is the core area of ​​the UHPC node.

2. The UHPC-connected double-post-tensioned prestressed concrete frame structure system according to claim 1, characterized in that, The double-post-tensioned precast prestressed concrete composite beam (3) consists of a precast post-tensioned prestressed concrete beam (7), a beam composite layer (8), and a second post-tensioned prestressing tendon (9); the composite slab (18) consists of a precast concrete slab (19) and a slab composite layer (20) cast on the slab.

3. The UHPC-connected double-post-tensioned prestressed concrete 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 double post-tensioned precast prestressed concrete composite beam (3) are all provided with recessed grooves or U-shaped grooves.

4. The UHPC-connected double-post-tensioned prestressed concrete 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 double post-tensioned precast prestressed concrete composite beam (3) are divided into a dense zone and a non-dense zone.

5. The UHPC-connected double-post-tensioned prestressed concrete frame structure system according to claim 1, characterized in that, The top surfaces of the precast post-tensioned prestressed concrete beam (7) and the precast concrete slab (19) are provided with a rough surface layer.

6. The construction method of the UHPC-connected double-post-tensioned prestressed concrete 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 post-tensioned prestressed concrete beam (7), and precast concrete slab (19); among them, the precast concrete lower column (2) and precast concrete upper column (1) need to reserve sufficient anchorage length for the longitudinal reinforcement extending into the core area (4) of the node; when constructing the post-tensioned prestressed concrete beam (7), the first post-tensioned prestressing tendon (17) and the second post-tensioned prestressing tendon (9) are pre-embedded in the beam according to the design position, and at both ends Leave sufficient length, then pour concrete, and when the concrete has cured to sufficient strength, tension the first prestressing tendon (17) and set clamps and anchors at both ends; among them, when the first post-tensioned prestressing tendon (17) and the second post-tensioned prestressing tendon (9) are unbonded or loosely bonded prestressing tendons, they are directly embedded in the design position; when the first post-tensioned prestressing tendon (17) and the second post-tensioned prestressing tendon (9) are bonded prestressing tendons, corrugated pipes need to be embedded in the precast post-tensioned prestressed concrete beam (7); Step 2: After the precast components have been cured, hoist the precast concrete lower column (2) and install it on the foundation. Then, install an appropriate number of stirrups on the extended longitudinal main reinforcement (6) according to the design requirements. Step 3: Hoist the precast post-tensioned prestressed concrete beam (7) to the top surface of the precast concrete lower column (2), so that the bottom surface of the precast post-tensioned prestressed concrete beam (7) is flush with the top surface of the precast concrete lower column (2), and place the end of the precast post-tensioned prestressed concrete beam (7) on the precast concrete lower column (2) and fix it with a support. Since the beam already has prestress, it can be without a support. Among them, the ordinary steel bars (10) extending from the post-tensioned prestressed concrete beams (7) on both sides and the core area of ​​the node should be reasonably avoided and directly anchored 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 second post-tensioned prestressing tendon (9) that is embedded in the post-tensioned prestressed concrete beam (7) and extends out in the node core area according to the design position. When the second post-tensioned prestressing tendon (9) is a bonded prestressing tendon, a section of corrugated pipe is embedded in the node core area to form an integral whole with the corrugated pipe embedded in the post-tensioned prestressed concrete beam (7). When it is a slow-bonded prestressing tendon, a sleeve needs to be put on the slow-bonded tendon for the unbonded part of the node. 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 post-tensioned prestressed concrete beam (7) and fixed. Step 7: Pour the beam composite layer (8) and slab composite layer (20); Step 8: After the concrete of the beam composite layer (8) and slab composite layer (20) has been cured to sufficient strength, the second post-tensioned prestressing tendon (9) is tensioned. When the second post-tensioned prestressing tendon (9) is a bonded prestressing tendon, it is first threaded through the corrugated pipe and then tensioned. Finally, grouting is performed in the corrugated pipe of the bonded part of the beam and the joint. No grouting is performed for the unbonded prestressing tendon part of the joint. Step 9: Repeat the above production process to complete the double-post-tensioned prestressed concrete frame structure system.

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