Design method of delayed closure of key coupling beams in transfer structure and transfer structure

Abstract

The application relates to a delay closure design method of a key coupling beam in a conversion structure and the conversion structure. The method comprises the following steps: in the structure design stage, identifying a secondary beam conversion beam and a coupled wall above the secondary beam conversion beam, and determining at least one coupling beam of adjacent floors of the coupled wall above the secondary beam conversion beam as a key coupling beam; during construction of the secondary beam conversion beam and an upper main body structure, only pre-burying stress steel bars of the key coupling beam, keeping a formwork of the key coupling beam to be set up and in an empty mode, monitoring vertical deformation of the secondary beam conversion beam and the upper main body structure in real time, and judging whether the vertical deformation is stable according to a preset quantitative judgment standard; and when it is judged that the vertical deformation is stable, pouring concrete into the key coupling beam for closure. Through time sequence control of the delay closure of the key coupling beam, the problem of insufficient shear wall shear capacity of the secondary beam conversion coupled wall caused by deformation of the conversion beam is solved.

Description

Technical Field

[0001] This invention relates to the field of architectural design and construction technology, and in particular to a delayed closure design method for key connecting beams in a transfer structure and the transfer structure itself. Background Technology

[0002] As high-rise buildings develop towards multi-functionality and integration, the upper part of the building requires small-space layouts for residences or offices, while the lower part demands large-space layouts for commercial spaces or lobbies. To resolve this contradiction, structural transfer floor technology has emerged. Among various transfer structure forms, beam-type transfer floors are the most widely used due to their direct load transfer, simple construction, and good economy. Their basic principle is: by setting up large-section transfer beams, the load of the upper structure's shear walls is transferred to the lower frame columns or shear walls, thereby achieving a large space at the bottom.

[0003] However, when the structural form is complex, especially when the transfer beam is not directly supported by the frame columns (i.e., secondary beams are used as transfer beams) to transfer coupled walls (i.e., multiple shear walls connected by coupling beams), the existing technology has the following significant drawbacks, posing a great challenge to structural design:

[0004] 1) Deformation problem caused by insufficient stiffness of the transfer beam

[0005] Compared to main beam transfer beams, the height and width of transfer beams in secondary beam transfer beams are usually limited, resulting in lower linear stiffness. Under the vertical load of the upper multi-story shear walls, the secondary beam transfer beams will experience significant vertical deflection. Actual measurements and analysis show that when the upper supporting floors exceed three stories, the mid-span deflection of the secondary beam transfer beam can reach 1 / 600 to 1 / 400 of its span, far exceeding the deflection limit of conventional beams.

[0006] 2) Excessive additional shear force in shear walls caused by coupling beam restraint

[0007] This is the core pain point of existing technology. When the secondary beam or transfer beam undergoes vertical deformation, the shear wall supported on it will deform accordingly. However, the shear wall is strongly constrained on both sides by the already cast-in-place connecting beams in the adjacent floors. This constraint forces the shear wall to bear not only the huge vertical load, but also the additional shear force generated by the deformation difference.

[0008] Based on mechanical analysis, the value of this additional shear force can be estimated using the following simplified formula:

[0009] ΔV = K beam · δ deflection

[0010] Among them, K beam δ is the equivalent shear stiffness of the coupling beam. deflection This represents the difference in vertical deflection of the transfer beam at the location of the connecting beam. Due to K...beam The additional shear force ΔV is usually large, and it is very easy for it to exceed the shear bearing capacity of the shear wall section, leading to brittle shear failure of the wall.

[0011] 3) The interaction mechanism between the transfer beam and the shear wall is complex.

[0012] In high-rise buildings employing beam-type transfer floors, the transfer beams and the shear walls of several upper floors exhibit a significant "co-interaction" phenomenon: the deformation of the transfer beams is transmitted upwards, affecting the force distribution within the shear walls of the upper floors; simultaneously, the constraint stiffness of the coupling beams, the deformation of the transfer beams, and the shear force distribution within the shear walls are interconnected, resulting in an actual stress state that significantly deviates from the initial design assumptions. Traditional structural design software struggles to accurately simulate this complex mechanical process, introducing substantial uncertainty into structural design.

[0013] 4) Conventional solutions are costly in terms of economics.

[0014] To alleviate these problems, traditional designs typically employ the following measures: significantly increasing the cross-section of transfer beams (even using steel-concrete composite beams) to improve their stiffness and reduce deformation; and increasing the thickness and reinforcement ratio of shear walls to enhance their shear capacity. However, these measures significantly increase material usage and construction difficulty, are economically inefficient, and are difficult to implement in certain situations (such as when building space is limited).

[0015] 5) The significant impact of construction sequence on the final stress state

[0016] The final stress state of a secondary beam-transfer coupled wall structure is closely related to the construction sequence. If the coupling beam is poured simultaneously with the floor slab and shear wall in the conventional sequence, the coupling beam will have already formed stiffness and constrained the shear wall before the deformation of the transfer beam occurs. This means that the additional shear force generated during construction will be "locked" within the structure and will accompany the structure for its entire life. However, current technology lacks effective construction control methods for this.

[0017] In summary, there is an urgent need to propose a safe, economical, and easy-to-implement construction method and structure to systematically solve the problem of insufficient shear bearing capacity of the shear wall caused by the deformation of the transfer beam in the secondary beam transfer coupled wall. Summary of the Invention

[0018] The purpose of this invention is to provide a delayed closure design method and a transfer structure for key connecting beams in a transfer structure, so as to solve the problem of insufficient shear bearing capacity of the shear wall caused by the deformation of the transfer beam in the secondary beam transfer coupling wall.

[0019] To achieve the above objectives, the present invention provides a delayed closure design method for key connecting beams in a transfer structure, comprising the following steps:

[0020] During the structural design phase, secondary beams and transfer beams and the connecting walls above them are identified, and at least one connecting beam in the connecting wall located on the adjacent floor above the secondary beam and transfer beam is identified as a critical connecting beam.

[0021] During the construction of the secondary beam transfer beam and the upper main structure, only the reinforcing steel bars of the key connecting beam are pre-embedded, and the formwork of the key connecting beam is completed and in a state of empty formwork.

[0022] The vertical deformation of the secondary beam transfer beam and the upper main structure is monitored in real time, and the stability of the vertical deformation is determined according to the preset quantitative judgment standard.

[0023] Once the vertical deformation is determined to be stable, the key connecting beam is then joined by concrete pouring.

[0024] Optionally, a construction simulation analysis is performed based on the stiffness of the secondary beam transfer beam, the magnitude of the upper load, and the cross-sectional dimensions of the coupled wall to determine the number and location of the key connecting beams on different floors, so that the maximum shear stress of the coupled wall after delayed closure meets the preset safety factor requirements.

[0025] Optionally, the preset safety factor requirements are as follows:

[0026] τ max (N) ≤ τ limit / γ

[0027] Where, τ max (N) represents the calculated maximum shear stress in the coupling wall after the critical connecting beam of the Nth floor is delayed in closure; τ limit γ represents the limit value of the cross-sectional shear strength of the coupled wall; γ is the safety factor.

[0028] Optionally, the reinforcing bars include at least longitudinal reinforcing bars, stirrups, and web bars.

[0029] Optionally, the length of the reinforcing steel bar reserved in the empty mold area shall not be less than 40 times the diameter of the reinforcing steel bar.

[0030] Optionally, the preset quantitative judgment standard is: through on-site measurement or construction simulation analysis, it is confirmed that the daily change of the maximum vertical deflection at the mid-span of the secondary beam transfer beam does not exceed 1 mm for 7 consecutive days, or the cumulative change reaches more than 90% of the final calculated deformation.

[0031] Optionally, while keeping the key connecting beam in an empty formwork state, the floor slabs and shear walls on the same floor as the key connecting beam are constructed in the normal sequence, and the corresponding floor slab formwork support systems are set up independently and do not depend on the support of the key connecting beam.

[0032] Optionally, before the key connecting beam is poured and closed with concrete, the delayed closure construction method further includes: roughening and cleaning the concrete interface at the junction of the end of the key connecting beam and the existing shear wall or beam.

[0033] Optionally, the concrete pouring and closure operation may be carried out after the main structure is capped, or at a specific construction stage determined by construction simulation analysis, when the upper dead load has been basically applied and the deformation tends to converge.

[0034] Based on the same technical concept, the present invention also provides a conversion structure, which is constructed using the delayed closure design method of the key connecting beam in the conversion structure as described above. In the final formed state, the key connecting beam, the connecting wall and the upper main structure form an integral force-bearing system.

[0035] In the delayed closure design method for key connecting beams in the transfer structure provided by this invention, the connecting beams located on adjacent floors above the secondary beam transfer beam are not cast simultaneously with the same-floor slab and coupling walls in the conventional sequence. Instead, these connecting beams are defined as "key connecting beams." By controlling the timing of delayed closure of the key connecting beams, a deformation release mechanism is established. During the construction phase of the transfer beam and the superstructure, since the key connecting beams are not yet filled with concrete (i.e., in an empty formwork state), they do not provide stiffness constraints on the connected wall segments, allowing the wall segments to deform freely with the transfer beam, thereby completely eliminating the additional shear force caused by the deformation difference. The key connecting beam is then closed after the structural deformation has stabilized. At this time, the connecting beam only bears the conventional service load and does not need to bear the historical additional stress. This method does not require a significant increase in the cross-section of the transfer beam, significantly reducing material usage and construction difficulty, while ensuring the safety of the coupling walls and solving the problem of excessive shear resistance in the secondary beam transfer coupling walls. Attached Figure Description

[0036] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention. Wherein:

[0037] Figure 1 A flowchart of the delayed closure design method for key connecting beams in a conversion structure provided in Embodiment 1 of the present invention;

[0038] Figure 2 This is a schematic diagram of the conversion structure provided in Embodiment 1 of the present invention.

[0039] The attached figures are labeled as follows:

[0040] 1-Secondary beam transfer beam; 2-Coupling wall; 3-Key connecting beam. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0042] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0043] In the description of this invention, it should be understood that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0044] Furthermore, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes said element. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0045] Please refer to Figures 1-2 This invention provides a method for delayed closure design of key connecting beams in a transition structure, comprising the following steps:

[0046] S1. During the structural design phase, identify the secondary beam transfer beam 1 and the connecting wall 2 above it, and identify at least one connecting beam in the connecting wall 2 located on the adjacent floor above the secondary beam transfer beam 1 as the key connecting beam 3.

[0047] S2. During the construction of the secondary beam transfer beam 1 and the upper main structure, only the reinforcing steel bars of the key connecting beam 3 are pre-embedded, and the formwork of the key connecting beam 3 is completed and in a state of empty formwork.

[0048] S3. Monitor the vertical deformation of the secondary beam transfer beam 1 and the upper main structure in real time, and judge whether the vertical deformation is stable according to the preset quantitative judgment standard.

[0049] S4. After determining that the vertical deformation is stable, the key connecting beam 3 is closed by concrete pouring.

[0050] In conventional design, the transfer beam undergoes vertical deflection δ under the action of the superstructure load. deflection Since the coupling beam has already formed stiffness K beam This will exert a forced constraint on the wall piers, generating a huge additional shear force ΔV. released = K beam ·δ deflection This often leads to shear walls exceeding their shear resistance limits.

[0051] In this invention, instead of casting the connecting beams on adjacent floors above the secondary beam transfer beam 1 in the conventional order with the same-floor slab and connecting wall 2, these connecting beams are defined as "critical connecting beams 3". A deformation release mechanism is established by using delayed closure timing control for critical connecting beams 3, the mechanical principle of which is as follows:

[0052] During the construction of the secondary beam transfer beam 1 and the superstructure, since the key connecting beam 3 was not poured with concrete (i.e., in an empty formwork state), its rotational and horizontal constraints on the connected wall segments were almost zero.

[0053] When the transfer beam undergoes vertical flexural deformation under the action of the upper load, the coupling wall 2 above it can freely follow the deformation and will not generate additional shear force due to the forced constraint of the coupling beam.

[0054] After the structural deformation has basically stabilized, the concrete pouring of the aforementioned key connecting beam 3 will proceed. At this point, the closure of the connecting beam is completed under conditions of almost no initial stress. In subsequent service stages, this key connecting beam 3 will only bear the internal forces generated by conventional loads (such as earthquake and wind loads), without having to bear the huge additional shear forces caused by the deformation differences during construction.

[0055] The mathematical expression of this deformation release mechanism is:

[0056] V actual = V design + ΔV released

[0057] Among them, when the delayed closure design of the present invention is adopted, ΔV released Since the value is approximately 0, the design only needs to focus on the conventional load V.design This allows the deflection limit of the secondary beam transfer beam 1 to be relaxed to 1.5 to 2 times the conventional limit, significantly reducing construction difficulty and material costs.

[0058] The method provided by this invention does not require a significant increase in the cross-section of the transfer beam, which significantly reduces the amount of material used and the difficulty of construction, while ensuring the safety of the coupled wall 2 and solving the problem of excessive shear resistance of the secondary beam transfer coupled wall.

[0059] First, in the structural design phase, S1 is executed to identify the secondary beam transfer beam 1 and the connecting wall 2 above it, and at least one connecting beam in the connecting wall 2 located on the adjacent floor above the secondary beam transfer beam 1 is identified as a critical connecting beam 3. During the structural design phase, the designers first identify the secondary beam transfer beam 1 and the connecting wall 2 above it.

[0060] Specifically, construction simulation analysis is conducted based on the stiffness of the secondary beam transfer beam 1, the magnitude of the upper load, and the cross-sectional dimensions of the coupled wall 2 to determine the number and location of the key connecting beam 3 on different floors, so that the maximum shear stress of the coupled wall 2 after delayed closure meets the preset safety factor requirements.

[0061] The "at least one connecting beam on the adjacent floor above the secondary beam transfer beam 1" of the present invention is not limited to the first-floor connecting beam directly adjacent to the secondary beam transfer beam 1. According to structural calculation analysis, if delaying the pouring of the first-floor connecting beam alone is insufficient to reduce the shear force of the shear wall to within the safe limit, the pouring of the second-floor or even the third-floor connecting beams can be further delayed.

[0062] The preset safety factor requirements are as follows:

[0063] τ max (N) ≤ τ limit / γ

[0064] Where, τ max (N) represents the calculated maximum shear stress of the coupling wall 2 after the delayed closure of the critical connecting beam 3 on the Nth floor; τ limit τ is the shear strength limit of the section of the coupled wall 2; γ is the safety factor, generally taken as 1.2~1.5. For example, in a certain super high-rise project, through simulation analysis, when N=3 (i.e., delaying the coupling beams of the first, second and third floors), τ max If the safety factor requirements are met, then the connecting beams of these three floors are designated as critical connecting beams 3. This designation should be clearly marked in the design documents.

[0065] Next, S2 is executed. During the construction of the secondary beam transfer beam 1 and the upper main structure, only the reinforcing steel bars of the key connecting beam 3 are pre-embedded to ensure that the formwork of the key connecting beam 3 is completed and in an empty formwork state.

[0066] In this embodiment, during the construction of the secondary beam transfer beam 1 and the upper main structure, special structural measures are implemented for the identified key connecting beam 3.

[0067] Reinforcement Pre-embedding: The longitudinal reinforcing bars, web reinforcement, and stirrups of the key connecting beam 3 should be fully pre-embedded in the shear walls at both ends and the lower beam-slab structure according to design requirements. The length of the reinforcing bars pre-embedded in the formwork area should meet the specifications for reinforcement lap splicing or welding, preferably not less than 40 times the diameter of the reinforcing bars. For example, for 25mm diameter reinforcing bars, the pre-embedded length should be not less than 1000mm to ensure the strength of the later connection.

[0068] Empty formwork maintenance: The formwork for this critical connecting beam 3 will remain in an empty formwork state after completion, and concrete pouring will not be carried out for the time being. This means that during the construction phase, only the steel reinforcement skeleton exists at this location, and concrete rigidity has not yet been formed.

[0069] Construction joint treatment: Before the concrete pouring and closure of the key connecting beam 3, the delayed closure construction method also includes: roughening and cleaning the concrete interface at the junction of the end of the key connecting beam 3 and the existing shear wall or beam to ensure that the concrete poured later can form an integral whole with the existing structure.

[0070] The above structural requirements should be clearly stated in the design drawings as the basis for construction.

[0071] Preferably, while keeping the key connecting beam 3 in an empty formwork state, the floor slabs and shear walls on the same floor as the key connecting beam 3 are constructed in the normal sequence, and the corresponding floor slab formwork support system is set up independently and does not depend on the support of the key connecting beam 3.

[0072] Next, S3 is executed to monitor the vertical deformation of the secondary beam transfer beam 1 and the upper main structure in real time, and to determine whether the vertical deformation is stable according to the preset quantitative judgment standard.

[0073] In this embodiment, the vertical deformation of the secondary beam transfer beam 1 and the upper main structure is monitored in real time during the construction of the main structure. The preset quantitative judgment standard is: through on-site measurement or construction simulation analysis, it is confirmed that the daily change of the maximum vertical deflection at the mid-span of the transfer beam does not exceed 1 mm for 7 consecutive days, or the cumulative change has accounted for more than 90% of the final calculated deformation.

[0074] This quantitative judgment standard is based on the following considerations: Concrete shrinkage and creep develop rapidly in the early stages after load application, reaching 80% to 90% of the final deformation in approximately 3 to 6 months. Waiting until the deformation has basically stabilized before closing the coupling beams ensures that most of the deformation generated during the construction phase has been released, thus guaranteeing a low-stress state during the subsequent closure of the coupling beams. This quantitative judgment standard should be specified as a quality control requirement in the design documents.

[0075] Finally, in step S4, once the vertical deformation is deemed stable, concrete is poured to close the critical connecting beam 3. The concrete pouring and closure operation is performed after the main structure is capped, or at a specific construction stage determined by construction simulation analysis, where the upper dead load has been basically applied and the deformation tends to converge.

[0076] The complete design process of this conversion structure is described in detail below.

[0077] 1) Design of the lower support structure

[0078] The design includes the substructure supporting columns, walls, and main beams below the secondary beam transfer beam 1. The design must ensure that the substructure has sufficient load-bearing capacity and stability to withstand all loads during construction and use. Due to the use of delayed closure technology in the superstructure, the design of the substructure must consider the uncertainty of construction live loads and appropriately increase the safety margin.

[0079] 2) Transfer beam design

[0080] The cross-sectional dimensions, reinforcement, and concrete strength of the secondary transfer beam 1 are designed to ensure that it meets the required stiffness and load-bearing capacity. The biggest difference from traditional design is that the deflection of the transfer beam should be calculated according to this design method, taking into account the actual stress state after delayed closure.

[0081] 3) Design of reinforcement for the connecting wall 2 and reserved connecting beams on adjacent floors of the transfer floor

[0082] Design the connecting wall 2 and the floor slab section and reinforcement of the adjacent floors of the transfer floor.

[0083] Key structural design: The design of all reinforcement configurations for the key connecting beam 3, which requires delayed pouring, must ensure that the anchorage length of the stressed reinforcement into the wall segments at both ends meets the specification requirements (usually not less than 40 times the diameter of the reinforcement).

[0084] Drawing annotation: The design documents clearly specify the pouring range of the concrete for the connecting wall 2 and the floor slab of this floor, and prominently indicate that the location of the above-mentioned key connecting beam 3 is in an empty formwork state and no concrete is poured.

[0085] 4) Design of the superstructure of secondary beam transfer beam 1

[0086] The design proceeds from the second floor, third floor, and so on up to all upper floors above the secondary beam transfer beam 1. During this period, all other structural members (shear walls, floor slabs) adjacent to the key connecting beam 3 are designed in the normal sequence, with only the design at the key connecting beam 3 being delayed, leaving the reinforcement reserved and the formwork unused. This design approach of "partial delay, overall advancement" ensures the integrity of the building's functions.

[0087] 5) Deformation stability monitoring and design of conditions for coupling beam closure

[0088] Monitoring scheme design: The design phase clearly stipulates that the deformation of the secondary beam transfer beam 1 will be monitored after the main structure is capped (or at the time determined by the construction simulation). The measurement can be carried out periodically using dial gauges, displacement gauges or total stations.

[0089] Closure conditions are set: it is stipulated that the closure of the delayed key connecting beam 3 can only be carried out after the deformation meets the aforementioned "quantitative judgment criteria". At this time, the closure of the key connecting beam 3 is completed in a state with almost no initial stress. In the subsequent use stage, the key connecting beam 3 only bears the internal forces generated by conventional loads (such as earthquake and wind loads).

[0090] 6) Final finishing design

[0091] Complete the design of other non-structural components such as infill walls and decorations.

[0092] Based on the same inventive concept, this embodiment of the invention also proposes a conversion structure, which is constructed using the delayed closure design method of the key connecting beam in the conversion structure as described above. In the final formed state, the key connecting beam 3, the connecting wall 2, and the upper main structure form an integral force-bearing system.

[0093] Since the conversion structure provided by this invention belongs to the same inventive concept as the delayed closure design method of the key connecting beam in the conversion structure described above, the conversion structure provided by this invention has all the advantages of the delayed closure design method of the key connecting beam in the conversion structure described above. Therefore, the beneficial effects of the conversion structure provided by this invention will not be described in detail here.

[0094] It should be noted that the "deformation release mechanism" behind the method used in this invention has universality and is not limited to the secondary beam conversion coupled wall 2, but can also be extended to the following scenarios:

[0095] Shear wall cracking caused by excessive deformation of transfer beam during main beam transfer: Even in main beam transfer, if the stiffness of the transfer beam is relatively weak, the method of delaying the pouring of the upper connecting beam can be used to release deformation and prevent wall cracking.

[0096] Stress concentration at joints due to deformation differences during lapped column transitions: In lapped column structures, the connection points between the column and the wall or beam often experience significant stress due to inconsistent deformation. Delaying the pouring of concrete in the joint area, allowing the deformation to harmonize before closure, can effectively eliminate stress concentration at the joint.

[0097] Any additional internal force problems caused by "rigid nodes first, deformation later": For any structural form where there is a contradiction between "structural components forming stiffness too early" and "the main structure deforming later" (such as mega-frame structures, connected structures, etc.), the delayed closure concept of this invention can be used as a reference.

[0098] In summary, this invention provides a delayed closure design method for key connecting beams in a transfer structure, as well as the transfer structure itself. The core of this method lies in not simultaneously casting the connecting beam located on the adjacent floor above the secondary beam transfer beam 1 with the same-floor slab and the connecting wall 2 in the conventional sequence, but instead defining it as the "key connecting beam 3". By using delayed closure timing control for the key connecting beam 3, a deformation release mechanism is established. During the construction phase of the transfer beam and the superstructure, since the key connecting beam 3 is not yet poured with concrete (i.e., in an empty formwork state), it has no stiffness constraint on the connected wall segments, allowing the wall segments to deform freely with the transfer beam, thereby completely eliminating the additional shear force caused by the deformation difference. The key connecting beam 3 is then closed after the structural deformation has stabilized. At this point, the connecting beam only bears the conventional service load and does not need to bear historical additional stress. This method does not require a significant increase in the cross-section of the transfer beam, significantly reducing material usage and construction difficulty, while ensuring the safety of the connecting wall 2 and solving the problem of excessive shear resistance in the secondary beam transfer connecting wall.

[0099] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure are within the protection scope of the present invention. Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the present invention and its equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A delayed closure design method for key connecting beams in a transfer structure, characterized in that, Includes the following steps: During the structural design phase, secondary beams and transfer beams and the connecting walls above them are identified, and at least one connecting beam in the connecting wall located on the adjacent floor above the secondary beam and transfer beam is identified as a critical connecting beam. During the construction of the secondary beam transfer beam and the upper main structure, only the reinforcing steel bars of the key connecting beam are pre-embedded, and the formwork of the key connecting beam is completed and in a state of empty formwork. The vertical deformation of the secondary beam transfer beam and the upper main structure is monitored in real time, and the stability of the vertical deformation is determined according to the preset quantitative judgment standard. Once the vertical deformation is determined to be stable, the key connecting beam is then joined by concrete pouring.

2. The delayed closure design method for key connecting beams in the transition structure according to claim 1, characterized in that, Based on the stiffness of the secondary beam transfer beam, the magnitude of the upper load, and the cross-sectional dimensions of the coupled wall, a construction simulation analysis is conducted to determine the number and location of the key connecting beams on different floors, so that the maximum shear stress of the coupled wall after delayed closure meets the preset safety factor requirements.

3. The delayed closure design method for key connecting beams in the transition structure according to claim 2, characterized in that, The preset safety factor requirements are as follows: t max (N) ≤ τ limit / c Where, τ max (N) represents the calculated maximum shear stress in the coupling wall after the critical connecting beam of the Nth floor is delayed in closure; τ limit γ represents the limit value of the cross-sectional shear strength of the coupled wall; γ is the safety factor.

4. The delayed closure design method for key connecting beams in the transition structure according to claim 1, characterized in that, The reinforcing steel bars include at least longitudinal reinforcing steel bars, stirrups, and web reinforcement.

5. The delayed closure design method for key connecting beams in a transition structure according to claim 1 or 4, characterized in that, The length of the reinforcing steel bar reserved in the empty mold area shall not be less than 40 times the diameter of the reinforcing steel bar.

6. The delayed closure design method for key connecting beams in the transition structure according to claim 1, characterized in that, The preset quantitative judgment standard is: through on-site measurement or construction simulation analysis, it is confirmed that the daily change of the maximum vertical deflection at the mid-span of the secondary beam transfer beam does not exceed 1 mm for 7 consecutive days, or the cumulative change reaches more than 90% of the final calculated deformation.

7. The delayed closure design method for key connecting beams in a transfer structure according to claim 1, characterized in that, While the key connecting beam is kept in an empty formwork state, the floor slabs and shear walls on the same floor as the key connecting beam are constructed in the normal sequence, and the corresponding floor slab formwork support system is set up independently and does not depend on the support of the key connecting beam.

8. The delayed closure design method for key connecting beams in a transition structure according to claim 1, characterized in that, Before the key connecting beam is poured with concrete for closure, the delayed closure construction method further includes: roughening and cleaning the concrete interface at the junction of the end of the key connecting beam and the existing shear wall or beam.

9. The delayed closure design method for key connecting beams in a transition structure according to claim 1, characterized in that, The concrete pouring and closure operation is scheduled after the main structure is capped, or at a specific construction stage determined by construction simulation analysis, when the upper dead load has been basically applied and the deformation tends to converge.

10. A conversion structure, characterized in that, The structure is constructed using the delayed closure design method for the key connecting beam in the conversion structure according to any one of claims 1-9. In the final formed state, the key connecting beam, the connecting wall, and the upper main structure form an integral load-bearing system.

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