Hybrid prestressing tendon tensioning method for prestressed concrete T-shaped beam

Abstract

The invention relates to a mixed prestressing tendon tensioning method for a prestressed concrete T-shaped beam, which comprises the following steps: (1) a precast yard construction stage: arranging an anchoring block in a T-shaped beam body, and then pouring and forming reinforced concrete; tensioning construction of applying temporary prestress to the steel beam S0 through the anchoring block; after the temporary prestressed steel beams S0 are tensioned, the components are moved and stored; (2) in the field construction stage, tensioning construction of a permanent prestressed steel beam S1 is applied to a reserved hole channel of an original structure, a temporary prestressed steel beam S0 is removed after construction is completed, and S1 is larger than S0; the T-beam moving and erecting work is completed; and (3) an operation period reinforcing stage: applying and supplementing tensioning construction of the external prestress steel beam S2 through an external prestress anchoring device reserved by the anchoring block. Compared with the prior art, full-period prestress control of the prestressed concrete T-shaped beam from prefabrication, construction and operation, maintenance, management and maintenance periods can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of reinforced concrete, in particular to a mixed prestressed bundle tensioning method for prestressed concrete T-beams. Background Art

[0002] In recent years, with the vigorous development of transportation civil engineering projects, prefabricated prestressed concrete T-beams have been widely used in small and medium-span bridges. Prestressed concrete T-beams are widely favored for their strong spanning capacity, good economy, good crack resistance, high structural stiffness, convenient construction, good integrity, and wide range of applications.

[0003] With the changes in traffic complexity and environmental complexity, problems such as long-term prestress loss and stiffness degradation of prestressed concrete T-beams have gradually been discovered. With the development of concrete structure research and material technology, the shrinkage and creep of concrete has a great impact on prestress loss, especially the huge shrinkage and creep of early-age concrete. It is particularly important to control the impact of concrete shrinkage and creep during construction. Due to the fact that the prestressed material itself has a certain relaxation characteristic over time and the anchor loss of prestressed tensioning construction, the bridge structure put into operation will show the phenomenon of structural stiffness degradation over time. Therefore, prestressed reinforced concrete beams will inevitably face the need to improve or maintain structural stiffness through reinforcement construction during operation and maintenance.

[0004] A common and effective reinforcement method is to supplement external prestressing. Common external prestressing reinforcement construction requires the implantation of an anchor base on the original structure, which will inevitably cause destructive and disturbing construction on the original structure, which is not conducive to the durability of the structure; and the later external prestressing reinforcement construction will often be uncontrollable due to unfavorable construction conditions, great construction difficulty, poor construction effect and other reasons. The traditional construction method and the later operation and maintenance reinforcement construction method have many defects, so it is particularly important to effectively consider and solve the above problems in the production process of prestressed concrete T-beams. The traditional construction method mainly includes the following adverse effects: First, the prestress is applied too early, which is superimposed with the shrinkage creep period of the early age of concrete, resulting in a large loss of structural prestress; second, the prestress is tensioned on the prestressed reinforced concrete T-beam pedestal, and the grouting work after the application is completed takes up a lot of pedestal time, affecting the overall prefabrication efficiency; third, the prestress of the prestressed reinforced concrete T-beam is applied in place at one time, which is difficult to adjust later; fourth, the design and construction did not consider the reinforcement needs and construction convenience during the operation and maintenance period, resulting in the difficulty in carrying out the later operation and maintenance reinforcement work, and the design, construction and operation and maintenance work are relatively disconnected. Although CN113981808A discloses a structure and construction method of a segmented precast concrete T-beam, by adopting the technology of prestressing inside and outside the segment body, it avoids the adverse effects of the built-in anchor on the joints of the middle segments and ensures the construction quality. However, the above construction method still cannot achieve full-cycle prestress control from prefabrication to construction to later maintenance.

[0005] For the above reasons, during the construction of prestressed reinforced concrete T-beams, the influence of the shrinkage and creep characteristics of early-age concrete on prestress should be considered, the influence of rapid prestressing and grouting construction on the overall prefabrication efficiency should be considered, the device for adjusting the structural prestress in the later stage should be reserved, and the promotion of the integrated design, construction, operation and maintenance should be considered. Therefore, it is urgent to design a full-cycle structural prestress control method that can run through the design, construction, operation and maintenance period. Summary of the invention

[0006] The purpose of the present invention is to provide a hybrid prestressed tendon tensioning method for prestressed concrete T-beams in order to achieve full-cycle prestress control of the prestressed concrete T-beams from prefabrication, construction to operation and maintenance.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] The present invention provides a hybrid prestressed tendon tensioning method for a prestressed concrete T-beam, comprising the following steps:

[0009] (1) Prefabrication site construction phase:

[0010] Anchor blocks are set in the T-beam body, and then reinforced concrete is poured into shape;

[0011] Tension construction of temporary prestressed steel tendon S0 through anchor blocks;

[0012] After the temporary prestressed steel tendons S0 are tensioned, the components are moved and the beams are stored;

[0013] (2) On-site construction stage:

[0014] Apply the tensioning construction of permanent prestressed steel tendon S1 in the reserved channel of the original structure, and remove the temporary prestressed steel tendon S0 after the construction is completed, S1>S0;

[0015] Complete the T-beam transportation and erection work;

[0016] (3) Operational reinforcement phase:

[0017] The tensioning construction of the external prestressed steel strand S2 is supplemented by the external prestressed anchoring device reserved by the anchor block.

[0018] Furthermore, in step (1), the anchor block is horizontally symmetrically arranged at the bottom of the T-beam.

[0019] Furthermore, in step (1), the anchor block includes an anchor block body and an internal anchor plate connected to the anchor block body. Since the anchor block body is subjected to bending, tension and shear coupling effects, the internal anchor plate can serve as an anchoring anti-pullout device to enhance the stability of the anchor block body.

[0020] Furthermore, the internal anchoring plate is connected to the bottom plate stirrup inside the T-beam, and the end of the anchoring block body extends out of the bottom of the T-beam after the reinforced concrete is cast.

[0021] Furthermore, a stiffening plate is provided at a crack-prone position of the interface between the anchor block body and the concrete.

[0022] Furthermore, the anchor block body is provided with external prestressed holes and internal steel bundle reserved holes.

[0023] Furthermore, the external prestressed hole is opened in the portion of the anchor block body extending out of the T-beam, and is used to penetrate the prestressed steel strand S0 and the supplementary prestressed steel strand S2.

[0024] Furthermore, the reserved holes for the steel strands in the body are used to penetrate the permanent prestressed steel strand S1.

[0025] Furthermore, the anchor block body is provided with reserved steel bar holes for the bottom plate longitudinal bars to pass through.

[0026] Furthermore, a plurality of shear steel keys are arranged on the anchor block body. Since the anchor block body is a steel block, the mechanical engagement performance between the steel block and the concrete is poor, and the mechanical engagement performance between the anchor block and the reinforced concrete structure is enhanced by arranging the shear steel keys.

[0027] Furthermore, in step (1), the strength of the temporary prestressed steel strand S0 satisfies:

[0028] S0≥η*

Max(M0 存梁 ,M0 吊装 )S0'+Ss'+SV'

[0029] Where η is the safety redundancy factor, M0 存梁 is the bending moment caused by the dead load in the beam stage, M0 吊装 is the bending moment caused by the dead load during the hoisting stage, S0' is the prestress loss caused by shrinkage creep, Ss' is the loss under the anchor of the prestress tension, and SV' is the impact of the weight acceleration during the hoisting of the component.

[0030] Furthermore, in step (2), the setting of the permanent prestressed steel strand S1 takes into account the effects of the second-phase dead load, vehicle load and 10-year creep.

[0031] Furthermore, in step (3), the strength of the supplementary prestressed steel strand S2 satisfies:

[0032] S2 ≥ η*(M2+M2');

[0033] Where η is the safety redundancy factor, M2 is the structural stiffness loss determined by comprehensive methods such as bridge load test and structural non-destructive material test, and M2' is the loss of prestress under the anchor.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The present invention sets prestressed anchor blocks during the prefabrication of the component reinforcement skeleton, and realizes full-cycle prestress control from prefabrication, construction to operation and maintenance by applying temporary prestressed steel strands S0, permanent prestressed steel strands S1 and supplementary prestressed steel strands S2 in stages.

[0036] (2) The present invention meets the needs of lifting and moving during the storage of beams by tensioning the hybrid prestressed tendons in vitro. The tensioning of temporary prestressed tendons can effectively reduce the loss of permanent prestress of the structure caused by the early shrinkage and creep of concrete during the storage of beams. The reserved hybrid prestressed tendon tensioning ports can also deal with the problems of stiffness degradation and reduced crack resistance of the structure due to long-term deflection during later operation and maintenance.

[0037] (3) The anchor block of the present invention is provided with reserved external prestressed holes, internal steel bundle reserved holes and steel bar reserved holes as reinforcement ports, which are convenient for applying temporary prestressed steel bundle S0, permanent prestressed steel bundle S1 and supplementary prestressed steel bundle S2 after the T-beam is cast in concrete.

[0038] (4) Compared with the traditional prestressing technology, the hybrid prestressing beam tensioning method of the present invention has better transportation flexibility and higher construction efficiency; it can better control the state of permanent prestressing; it reserves a convenient and reliable reinforcement method for the later prestressing loss, greatly reducing the difficulty and cost of the later external prestressing reinforcement and maintenance construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the three-dimensional structure of the anchor block of the present invention.

[0040] Figure 2 It is a schematic plan view of the anchor block of the present invention.

[0041] Figure 3 It is a relationship diagram of the anchor block of the present invention, the T-beam steel bars and the prestressing space distribution.

[0042] Figure 4 This is a positional relationship diagram of the anchor block and the T-beam after the concrete pouring of the present invention is completed.

[0043] Figure 5 The diagram shows the shape of the anchor block and its cross-sectional proportion to the T-beam.

[0044] Figure 6Schematic diagram of the work of tensioning temporary prestressed tendons during construction in the prefabrication yard.

[0045] Figure 7 Schematic diagram of the work of tensioning permanent prestressed tendons during on-site construction.

[0046] Figure 8 Schematic diagram of the work to supplement the prestressed tendon tensioning for construction during the operation period.

[0047] Fig. 9 Schematic diagram of the tensioning workflow and logical relationship of the hybrid prestressed bundle at each stage in Example 3.

[0048] Description of the markings in the figure:

[0049] 1-T-beam, 11-bottom plate stirrups, 12-chamfered stirrups, 13-concrete, 14-bottom plate longitudinal reinforcement;

[0050] 2-anchor block, 21-anchor block body, 22-internal anchor plate, 23-stiffening plate, 24-external prestressed hole, 25-internal steel bundle reserved hole, 26-reinforcement reserved hole, 27-shear steel key. DETAILED DESCRIPTION

[0051] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0052] In the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention; the terms "first", "second", and "third" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance; in addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0054] The above embodiments can be implemented individually or in any combination of two or more. The above embodiments are described in more detail below with reference to specific examples.

[0055] Embodiment 1:

[0056] This embodiment provides a hybrid prestressed tendon tensioning method for a prestressed concrete T-beam 1, which specifically includes the following steps:

[0057] (1) Prefabrication site construction phase:

[0058] Anchor blocks are set in the T-beam body, and then reinforced concrete is poured and formed; the temporary prestressed steel tendons S0 are tensioned through the anchor blocks; after the temporary prestressed steel tendons S0 are tensioned, the components are moved and the beams are stored;

[0059] (2) On-site construction stage:

[0060] Apply the tensioning construction of permanent prestressed steel strand S1 in the reserved channel of the original structure. After the construction is completed, remove the temporary prestressed steel strand S0, S1>S0; complete the transportation and erection of T beams;

[0061] (3) Operational reinforcement phase:

[0062] The tensioning construction of the external prestressed steel strand S2 is supplemented by the external prestressed anchoring device reserved by the anchor block.

[0063] This embodiment realizes full-cycle prestress control during prefabrication, construction, and operation and maintenance by applying temporary prestressed steel strands S0, permanent prestressed steel strands S1, and supplementary prestressed steel strands S2 in stages. Only applying prestressed steel strands S0 during the prefabrication site construction phase can effectively avoid premature application of permanent prestress and superposition of early-age shrinkage creep of concrete, thereby reducing prestress loss; applying permanent prestressed steel strands S1 during the on-site construction phase can avoid mutual interference between prefabrication site construction and on-site construction; during the reinforcement phase of the operation period, applying supplementary prestressed steel strands S2 through the reserved external prestressed holes 24 can realize later adjustment of the structural prestress.

[0064] Embodiment 2:

[0065] This embodiment provides a hybrid prestressed tendon tensioning method for a prestressed concrete T-beam 1, which specifically includes the following stages and specific steps:

[0066] (1) Prefabrication site construction phase:

[0067] Anchor blocks are set in the T-beam body, and then reinforced concrete is poured and formed; the temporary prestressed steel tendons S0 are tensioned through the anchor blocks; after the temporary prestressed steel tendons S0 are tensioned, the components are moved and the beams are stored.

[0068] The difference from Example 1 is that Figure 1-3 As shown, the present embodiment has two anchor blocks 2, and the two anchor blocks 2 are horizontally and symmetrically arranged at the bottom of the T-beam 1, which improves the overall stability and bearing capacity of the anchoring system and avoids the stress concentration problem that may be caused by a single anchor block 2. The anchor block 2 includes an anchor block body 21 and an internal anchor plate 22 connected to the anchor block body 21. Among them, the internal anchor plate 22 is connected to the bottom plate stirrups 11 inside the T-beam 1, which enhances the integrity of the anchor block 2 and the beam body and further improves the crack resistance of the structure; the end of the anchor block body 21 extends out of the bottom of the T-beam 1 after the reinforced concrete is cast. A stiffening plate 23 is added to the crack-prone position of the interface between the anchor block body 21 and the concrete 13, which can effectively disperse stress concentration and reduce the risk of cracking of the concrete 13.

[0069] The anchor block body 21 of this embodiment is provided with external prestressed holes 24 and internal steel bundle reserved holes 25. Among them, the external prestressed holes 24 are provided in the part of the anchor block body 21 extending out of the T-beam 1, and are used to penetrate the prestressed steel bundle S0 and the supplementary prestressed steel bundle S2, and the internal steel bundle reserved holes 25 are used to penetrate the permanent prestressed steel bundle S1, which realizes the independent arrangement of prestressed steel bundles at different stages, makes the tensioning and replacement of prestressed steel bundles more convenient, and reduces the construction difficulty. The anchor block body 21 is provided with steel bar reserved holes 26 for the bottom plate longitudinal reinforcement 14 to penetrate, which can ensure the effective connection between the anchor block 2 and the beam body steel bars and improve the integrity of the structure. A number of shear steel keys 27 are arranged on the anchor block body 21, and the arranged shear steel keys 27 enhance the bonding force between the anchor block 2 and the concrete 13, and prevent the anchor block 2 from slipping or falling off during the prestressing tensioning process.

[0070] The strength of the temporary prestressed steel tendon S0 in this embodiment should meet the following requirements:

[0071] S0≥η*

Max(M0 存梁 ,M0 吊装 )S0'+Ss'+SV'

[0072] Where η is the safety redundancy factor, M0 存梁 is the bending moment caused by the dead load in the beam stage, M0 吊装 is the bending moment caused by the dead load during the hoisting stage, S0' is the prestress loss caused by shrinkage creep, Ss' is the loss under the anchor of the prestress tension, and SV' is the impact of the weight acceleration during the hoisting of the component.

[0073] In this embodiment, the external temporary prestressed steel tendon S0 is compared with M0 存梁 and M0 吊装 , select the most unfavorable bending moment value to ensure that the design of the temporary prestressed tendon S0 can cover the most unfavorable load condition; provide additional safety margin to ensure that the temporary prestressed tendon can reliably resist various adverse effects.

[0074] (2) On-site construction stage:

[0075] The permanent prestressed steel strand S1 is tensioned in the reserved channel of the original structure. After the construction is completed, the temporary prestressed steel strand S0 is removed, S1>S0; and the T-beam transportation and erection work is completed.

[0076] Since the setting of the permanent prestressed steel tendon S1 takes into account the secondary dead load, vehicle load and 10-year creep effect, S1>S0, ensuring that the structure has sufficient bearing capacity both in normal use and in the ultimate limit state.

[0077] The permanent prestressed steel bundle S1 of this embodiment takes into account the second-phase constant load (such as bridge deck pavement, guardrails, etc.), ensuring that the T-beam can withstand these loads under normal use to prevent structural deformation or cracking. Vehicle load is an important live load in bridge design. The setting of the permanent prestressed steel bundle S1 can effectively resist the bending moment and shear force caused by vehicle load and improve the bearing capacity of the structure. In addition, the concrete 13 will creep under long-term load, resulting in prestress loss and structural deformation. The permanent prestressed steel bundle S1 takes into account the influence of 10-year creep, ensuring that the prestress can still meet the structural requirements in long-term use and avoid performance degradation caused by creep.

[0078] Therefore, the setting of the permanent prestressed steel strand S1 in this embodiment not only meets the bearing requirements of the structure under normal use, but also takes into account the influence of long-term loads and creep, optimizes the stress state of the structure, improves the crack resistance and safety, and has significant economic and technical advantages. It is a key measure to achieve the design goals of the bridge.

[0079] (3) Operational reinforcement phase:

[0080] The tensioning construction of the external prestressed steel strand S2 is supplemented by the external prestressed anchoring device (specifically, the external prestressed hole 24) reserved by the anchoring block.

[0081] The strength of the supplementary prestressed steel tendon S2 satisfies: S2≥η*(M2+M2'); where η is the safety redundancy coefficient, M2 is the structural stiffness loss determined by comprehensive methods such as bridge load test and structural non-destructive material test, and M2' is the loss of prestress under the anchor.

[0082] In this embodiment, the structural stiffness loss M2 determined comprehensively through bridge load tests, structural non-destructive material tests and other methods can effectively compensate for these losses and restore the stiffness and bearing capacity of the structure. The provision of supplementary prestressed steel strands S2 can further improve the bearing capacity of the structure, ensuring that the bridge can safely withstand the design load during the operation period; enhance the bending and shear resistance of the structure, and prevent damage caused by sudden loads (such as earthquakes and wind loads). Supplementary prestressed steel strands S2 realize full-cycle performance control from design, construction to operation and maintenance, ensuring that the structure can meet performance requirements throughout its life cycle.

[0083] Embodiment 3:

[0084] This embodiment proposes a method for tensioning a hybrid prestressed beam for a prestressed T-beam 1. The construction flow chart and logic relationship diagram of the hybrid prestressed beam for prestressed concrete T-beams from factory processing to on-site installation to reinforcement during operation are shown in FIG. Fig. 9 The hybrid prestressed tendon tensioning method of this embodiment reduces the initial prestress loss of the internal steel tendons by adjusting the tensioning sequence and timing of the internal and external prestresses, optimizes the later external prestressed tendon reinforcement design, reduces the difficulty of external prestressed tendon reinforcement construction during the operation and maintenance period, and optimizes the cost control of external prestressed tendon reinforcement construction during the operation and maintenance period.

[0085] The tensioning method of the hybrid prestressed bundle of this embodiment can be specifically implemented by the following technical solutions:

[0086] (1) Before the construction of precast prestressed concrete T-beams, the design and production of external prestressed anchor plates should fully consider the influence of structural reinforcement and bundle arrangement, the influence of external prestressing force, the bond slip between the anchor plate and reinforced concrete, and the influence of the size of the anchor steel plate on the structure.

[0087] Specifically, during the prefabrication of the steel skeleton of the component, a prestressed anchor block 2 is arranged at the side edge of the horseshoe bottom inside the T-beam 1. The strength and stiffness of the anchor block 2 itself meet the tensioning requirements of the prestress S0 and S2. The conflict position between the anchor block 2 itself and the structural steel bars and prestressed pipes is solved by opening holes (i.e., external prestressed holes 24, internal steel bundle reserved holes 25, and steel bar reserved holes 26). The rigidity requirements of the interface between the anchor block body 21 and the concrete 13 that is prone to cracking are met by the design of the stiffening plate 23. The anchor block body 21 is subject to the coupling effect of bending, tension and shear, and its stability is enhanced by the anchor pull-out device (i.e., the internal anchor plate 22) arranged at the tail. The anchor block body 21 is a steel block, and the mechanical bite performance between the steel block and the concrete 13 is poor. Therefore, this embodiment enhances the mechanical bite performance between the anchor block 2 and the reinforced concrete structure by arranging a shear steel key 27. The main structure of the anchor block 2 is as follows Figure 1 As shown in the figure, the alternating arrangement of anchor holes and steel bars and prestressed tendons in the member body is as follows Figure 2As shown, the three-dimensional shape of the anchor block 2 is as follows Figure 3 shown.

[0088] (2) About 7 days after the reinforced concrete is cast, the strength and elastic modulus of the component concrete meet the design and specification requirements, and the external prestressed steel strand S0 is tensioned on the anchor block 2. After the concrete is poured, the anchor block 2 only has the external prestressed hole 24, which is symmetrically located on both sides of the beam horseshoe (lower flange plate). After the prefabrication, the three-dimensional position relationship between the T beam and the anchor block 2 is as follows: Figure 4 As shown, the local cross-sectional shape and its size ratio are as follows Figure 5 shown.

[0089] (3) During the prefabrication construction phase in the prefabricated beam factory, only the transportation and storage of prefabricated components need to be considered. The temporary external prestressed tendon S0 mainly considers the influence of the bending moment caused by the bare beam constant load M0 during lifting and storage. The external temporary prestressed tendon S0 is tensioned by anchor block 2 to balance the adverse influence of the bending moment. The strength design of the temporary prestressed tendon S0 mainly considers the influence of resisting the M0 storage caused by the structure storage boundary and the M0 lifting caused by the lifting boundary. The larger of the two is considered in the calculation. However, the prestress loss S0' caused by a certain shrinkage creep, the anchor loss Ss' of the prestress tensioning, and the impact of the weight acceleration Sv' during the component lifting should be considered.

[0090] Therefore, the design expression of S0 is S0≥Max(M0 存梁 ,M0 吊装 )S0'+Ss'+SV'. For safety reasons, the safety redundancy factor η is added, and the final design expression of S0 is:

[0091] S0≥η*【Max(M0 存梁 ,M0 吊装 )S0'+Ss'+SV'].

[0092] After pouring concrete, the components are formed and the strength and elastic modulus of the material meet the tensioning requirements. The components are tensioned by external temporary tendons. The components are slightly arched. After the requirements for lifting and moving the beam are met, the beam is stored. The prestressing state of the beam is as follows: Figure 6 shown.

[0093] (4) When the conventional storage beam is completed, the concrete has an age of 60 to 90 days, and the early-age shrinkage and creep of the concrete have been basically completed. The subsequent concrete shrinkage and creep have little effect on the loss of permanent prestress. At this time, the permanent prestress S1 of the tensioned structure can minimize the loss of permanent prestress S1 during construction; while tensioning the permanent prestress S1, the temporary prestress S0 needs to be removed to complete the prestress system conversion. In general, the setting value of the permanent prestressed tendon S1 takes into account the second-phase dead load + vehicle load + 10-year creep effect, S1>S0.

[0094] The total number of prestressed tendons S1 is large, and generally requires multiple symmetrical tensioning to complete. Therefore, after the permanent prestressed tendons S1 are tensioned, the temporary prestressed tendons S0 have naturally relaxed, and the permanent prestressed tendons S1 can seamlessly replace the temporary prestressed tendons S0. At this time, the beam is in a slightly arched state, with good working condition and prestress reserve. The overall state is as follows: Figure 7 shown.

[0095] (5) Complete the T-beam erection work and complete the subsequent construction steps until the bridge is completed.

[0096] (6) After a period of operation (for example, 10 years later), due to the combined effects of traffic loads, climate environment, concrete carbonization creep and other factors, the permanent prestressing force will be lost to a certain extent, and the material properties will be deteriorated to a certain extent, causing a certain attenuation of the structural stiffness and crack resistance. It is necessary to carry out certain maintenance and reinforcement construction to restore the mechanical properties of the components. At this time, the structural stiffness loss M2 can be comprehensively determined by methods such as bridge load test + structural non-destructive material test, and external prestressing can be supplemented by reserving anchor blocks 2. The amount of external prestressing supplementary tensioning should take into account the stiffness M2 that has been lost in the structure, the loss of prestress under the anchor M2' and a certain safety redundancy factor η. Therefore, the strength of the supplementary prestressed steel strand S2 satisfies: S2≥η*(M2+M2'). At this time, the component has restored a certain amount of arching, and the overall state is as follows: Figure 8 shown.

[0097] This embodiment proposes a method for tensioning a hybrid prestressed bundle for a prestressed T-beam 1, which can be used in conjunction with PE antirust steel strands and tool clips for recycling, and can be used to apply temporary prestress with high freedom according to the hoisting boundary, beam storage boundary and prestress state of different reinforcement and bundle structures; through the construction conversion of external temporary bundles and internal permanent bundles during construction, the influence of early-age concrete shrinkage creep on the loss of permanent prestress of the structure is avoided; by quickly applying a small amount of external bundles to meet the needs of rapid hoisting and transportation of the beam body, the occupation time of the beam body pedestal is reduced, the turnover efficiency of the pedestal is improved, and the efficiency of prefabrication construction is improved; through the reserved anchoring device, the external prestressed anchoring port can be reserved for the later operation and maintenance reinforcement construction, reducing the difficulty of the later operation and maintenance reinforcement construction and the cost of the reinforcement construction. Through the reasonable use of this method, the construction efficiency of the prefabrication of the T-beam 1 during construction can be ensured, the minimum loss of permanent prestress of the beam body can be ensured, the simplicity and cost controllability of the external prestressed reinforcement construction during the later operation and maintenance can be ensured, and the practicality and durability of the prestressed concrete T-beam 1 can be improved.

[0098] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A hybrid prestressed tendon tensioning method for prestressed concrete T-beams, characterized in that: The following steps are involved: (1) Prefabrication site construction phase: Anchor blocks are set in the T-beam body, and then reinforced concrete is poured into shape; Tension construction of temporary prestressed steel tendon S0 through anchor blocks; After the temporary prestressed steel tendons S0 are tensioned, the components are moved and the beams are stored; (2) On-site construction stage: Apply the tensioning construction of permanent prestressed steel tendon S1 in the reserved channel of the original structure, and remove the temporary prestressed steel tendon S0 after the construction is completed, S1>S0; Complete the T-beam transportation and erection work; (3) Operational reinforcement phase: The tensioning construction of the external prestressed steel strand S2 is supplemented by the external prestressed anchoring device reserved by the anchor block.

2. A hybrid prestressed tendon tensioning method for prestressed concrete T-beams according to claim 1, characterized in that: In step (1), the anchor block is horizontally symmetrically arranged at the bottom of the T-beam.

3. A hybrid prestressed tendon tensioning method for prestressed concrete T-beams according to claim 1, characterized in that: In step (1), the anchor block includes an anchor block body and an in-body anchor plate connected to the anchor block body; The internal anchoring plate is connected with the bottom plate stirrup inside the T-beam, and the end of the anchoring block body extends out of the bottom of the T-beam after the reinforced concrete is cast.

4. A hybrid prestressed tendon tensioning method for prestressed concrete T-beams according to claim 3, characterized in that: A stiffening plate is additionally provided at a crack-prone position of the interface between the anchor block body and the concrete.

5. A hybrid prestressed tendon tensioning method for prestressed concrete T-beams according to claim 3, characterized in that: The anchor block body is provided with external prestressed holes and internal steel bundle reserved holes; The external prestressed hole is opened in the part of the anchor block body extending out of the T-beam, and is used to penetrate the prestressed steel strand S0 and the supplementary prestressed steel strand S2; the internal steel strand reserved hole is used to penetrate the permanent prestressed steel strand S1.

6. A hybrid prestressed tendon tensioning method for prestressed concrete T-beams according to claim 3, characterized in that: The anchor block body is provided with a steel bar reserved hole for the bottom plate longitudinal reinforcement to pass through.

7. A hybrid prestressed tendon tensioning method for prestressed concrete T-beams according to claim 3, characterized in that: A plurality of shear steel keys are arranged on the anchor block body.

8. A hybrid prestressed tendon tensioning method for prestressed concrete T-beams according to claim 1, characterized in that: In step (1), the strength of the temporary prestressed steel strand S0 satisfies: S0≥η*【Max(M0 存梁 ,M0 吊装 )S0’+Ss’+SV’】; Where η is the safety redundancy factor, M0 存梁 is the bending moment caused by the dead load in the beam stage, M0 吊装 is the bending moment caused by the dead load during the hoisting stage, S0' is the prestress loss caused by shrinkage creep, Ss' is the loss under the anchor of the prestress tension, and SV' is the impact of the weight acceleration during the hoisting of the component.

9. A hybrid prestressed tendon tensioning method for prestressed concrete T-beams according to claim 1, characterized in that: In step (2), the setting of the permanent prestressed steel strand S1 takes into account the secondary dead load, vehicle load and 10-year creep effect.

10. A hybrid prestressed tendon tensioning method for prestressed concrete T-beams according to claim 1, characterized in that: In step (3), the strength of the supplementary prestressed steel strand S2 satisfies: S2 ≥ η*(M2+M2'); Where η is the safety redundancy factor, M2 is the structural stiffness loss determined by comprehensive methods such as bridge load test and structural non-destructive material test, and M2' is the loss of prestress under the anchor.

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