Construction method for controlling cracking of suspended structural concrete floor slab

Abstract

This invention belongs to the field of building construction technology and discloses a construction method for controlling cracking in suspended concrete floor slabs. During the pouring of concrete floor slabs, a roof lifting structure set on the roof steel truss is used to lift the lifting layer of the suspended steel structure, so that the vertical deformation value of the lifting layer is less than the preset deformation threshold, reducing the possibility of cracking or the formation of cracks in the concrete floor slabs during the pouring process, optimizing the construction process, and significantly shortening the construction period of the main part of the suspended structure of the entire floor.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a construction method for controlling cracking in suspended concrete floor slabs. Background Technology

[0002] Full-floor suspended structures and partial-floor suspended structures cannot be generalized. Compared to partial-floor suspended structures, full-floor suspended structures are subject to greater loads, resulting in larger cumulative deformation and making it more difficult to control force and shape.

[0003] The main body of a suspended structure includes a suspended steel structure and floor slabs cast based on the suspended steel structure. Currently, the most common floor slab construction methods for suspended structure systems are mainly divided into two types. The first method involves installing the suspended steel structure first, and then pouring the concrete for the suspended floors. As the concrete for the floor slabs is poured layer by layer, the suspended structure undergoes corresponding vertical deformation under the weight of the floor slabs. This results in a difference in vertical deformation between the suspended end of the floor slab and the core tube end, and this difference increases continuously with the pouring of the floor slabs. When it exceeds a threshold, it will cause problems such as cracks or even deterioration of the floor slab at the core tube end. When the aforementioned problems are very serious, the second construction method is often used, which is to set a post-pouring strip near the core tube end of the floor slab. After the concrete for the suspended floors is poured, the post-pouring strip is sealed layer by layer. This construction process is complex, and there are often masonry walls, electromechanical pipelines, and other construction work around the core tube. Setting up the post-pouring strip will affect the construction process and progress of other disciplines. Summary of the Invention

[0004] The purpose of this invention is to provide a construction method for controlling cracking in suspended concrete floor slabs. This construction method can keep the concrete floor slab within a safe and controllable deformation range after the concrete floor slab is poured, reduce the possibility of cracking, and not affect the construction of other disciplines.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] The construction method for controlling cracking in suspended concrete floor slabs includes the following steps:

[0007] Erect a temporary support system;

[0008] The construction core tube is located at the center of the temporary support system;

[0009] Based on the temporary support system, a suspended steel structure and a roof steel truss are constructed around the core tube. The suspended steel structure is divided into a lifting layer and a non-lifting layer. The lifting layer is supported on the temporary support system, and the non-lifting layer is supported under the roof steel truss. A gap is set between the lifting layer and the non-lifting layer.

[0010] A roof lifting structure is installed on the roof steel truss and connected to the lifting layer;

[0011] During the pouring of the floor slab, the lifting layer is lifted to ensure that the vertical deformation difference of the lifting layer is less than a preset deformation threshold.

[0012] After the floor slab is poured, the lifting layer is finally lifted to complete the permanent connection between the lifting layer and the non-lifting layer;

[0013] The roof lifting structure and the temporary support system were dismantled, and the main part of the suspended structure was completed.

[0014] Preferably, the construction of the suspended steel structure and the roof steel truss specifically includes the following steps:

[0015] The suspended steel structure is constructed from bottom to top using the sequential construction method up to the m-th floor, where n > m > 0, n is the total number of floors in the suspended structure, and m is a constant.

[0016] A connecting plate can be detachably installed on the structural steel column of the m-th floor;

[0017] Supporting steel columns are installed on the connecting plate and connected to the connecting plate. There is a gap between the supporting steel columns and the structural steel columns of the steel structure of the m-th layer. Construction of the roof steel truss 4 and the steel structure above the m-th layer continues. With the connecting plate as the boundary, the steel structure below the connecting plate is the lifting layer, and the steel structure above the connecting plate is the non-lifting layer. The supporting steel columns, as the structural steel columns of the non-lifting layer, can support the roof steel truss.

[0018] Remove the connecting plate to separate the lifting layer and the non-lifting layer.

[0019] Preferably, the non-lifting layer is constructed using the reverse construction method.

[0020] As a preferred option, 3 ≥ nm > 0.

[0021] Preferably, during the pouring of the floor slab, the force borne by the temporary support system does not exceed a preset bearing threshold.

[0022] Preferably, a force sensor is installed on top of the temporary support system before the construction of the suspended steel structure.

[0023] Preferably, when the lifting layer is lifted during the pouring of the floor slab, the roof lifting structure stops lifting when the vertical deformation difference of the lifting layer and the force borne by the temporary support system reach a preset control median value, wherein the control median value is less than the bearing threshold and the deformation threshold.

[0024] Preferably, during the construction of the suspended steel structure, multiple displacement sensors are installed on the suspended steel structure, and the multiple displacement sensors can measure the vertical deformation difference of the suspended steel structure.

[0025] Preferably, the floor slab is poured from bottom to top.

[0026] Preferably, the roof lifting structure is connected to the top layer of the lifting layer.

[0027] The beneficial effects of the present invention are as follows: In the construction method for controlling cracking of suspended concrete floor slabs in the present invention, the roof lifting structure installed on the roof steel truss is used to lift the lifting layer, which can control the degree of vertical deformation of the suspended steel structure during the construction of the concrete floor slab, so that it is always within the preset deformation threshold. There is no need to set up post-pouring strips and cracks or fissures are not easy to occur. The construction process is optimized and the construction period of the whole floor suspended structure is greatly shortened. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a temporary support system set on an existing structure in an embodiment of the present invention;

[0029] Figure 2 This is a structural schematic diagram of the suspended steel structure and the roof steel truss in an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the installation of the roof lifting structure in an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the floor slab pouring in an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the final suspended structure main body in an embodiment of the present invention.

[0033] In the picture:

[0034] 1. Temporary support system; 2. Lifting layer; 3. Non-lifting layer; 4. Roof steel truss; 5. Roof lifting structure; 6. Floor slab; 7. Core tube. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0036] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0037] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0038] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not 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 the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0039] Figures 1-5 The illustration shows a construction method for controlling cracking in suspended concrete floor slabs according to an embodiment of the present invention. This construction method is mainly applicable to suspended structures throughout the entire floor and includes the following steps:

[0040] S1, construction core tube 7 and temporary support system 1, with the core tube 7 located at the center of the temporary support system 1;

[0041] S2. Relying on the temporary support system 1, the suspended steel structure and the roof steel truss 4 are constructed around the core tube 7. The suspended steel structure includes a lifting layer 2 supported on the temporary support system 1 and a non-lifting layer 3 set under the roof steel truss 4. There is a gap between the lifting layer 2 and the non-lifting layer 3.

[0042] Step S2 specifically includes the following steps:

[0043] S21. The suspended steel structure is constructed from bottom to top using the sequential construction method up to the m-th floor, where m is a constant, n > m > 0, and n is the total number of floors in the suspended structure.

[0044] S22. Install a detachable connecting plate on the structural steel column of the steel structure in the m-th layer.

[0045] S23. Install supporting steel columns on the connecting plate. The supporting steel columns are detachably connected to the connecting plate. There is a gap between the supporting steel columns and the structural steel columns of the m-th layer steel structure. Continue construction of the roof steel truss 4 and the steel structure above the m-th layer. With the connecting plate as the boundary, the steel structure below the connecting plate is the lifting layer 2, and the steel structure above the connecting plate is the non-lifting layer 3. The supporting steel columns, as the structural steel columns of the non-lifting layer 3, can support the roof steel truss 4. The pressure of the non-lifting layer 3 is transferred to the lifting layer 2 by the connecting plate. The connecting plate plays the role of temporary support.

[0046] Generally, the number of non-lifting layers should not be too many to avoid excessive deformation during concrete pouring of the non-lifting layer 3. In this embodiment, 3≥nm>0, and when there are more than two non-lifting layers 3, the reverse construction method is adopted.

[0047] S24, Roof steel truss 4 and non-lifting layer 3 unloading: Remove the connecting plate to separate lifting layer 2 and non-lifting layer 3.

[0048] S3. Install the roof lifting structure 5 on the roof steel truss 4. The roof lifting structure 5 includes a power lifting device and a lifting line. One end of the lifting line is connected to the power lifting device, and the other end is connected to the lifting layer 2. Optionally, the power lifting device can be a jack or an electric winch. In this embodiment, the power lifting device is a jack, and the lifting line can be a steel strand.

[0049] Specifically, the lifting line is connected to the steel structure of the m-th layer.

[0050] S4. Pour concrete floor slab 6. During the pouring process, monitor the vertical deformation difference of the lifting layer 2 in real time. Lift the lifting layer 2 through the roof lifting structure 5 to ensure that the vertical deformation difference of the lifting layer 2 is less than the preset deformation threshold.

[0051] The deformation threshold refers to the permissible vertical deformation difference between the core tube end and the suspended end before cracking occurs during concrete pouring, provided that existing standards and design requirements are met. The deformation threshold is obtained as follows: based on the overall model of the suspended structure, a construction simulation analysis is performed on the entire construction process to determine the permissible vertical deformation difference for each layer of concrete slab 6 being poured. The construction simulation analysis can specifically employ ANSYS finite element analysis, which is existing technology and will not be described in detail in this embodiment.

[0052] The vertical deformation difference of the lifting layer 2 is obtained through displacement sensors. In step S2, when constructing the suspended steel structure, displacement sensors are installed on the lifting layer 2. Multiple sets of displacement sensors are set along the height direction of the lifting layer 2, with each set including at least two sensors. The two displacement sensors in the same set are located at the core tube end and the suspension end of the suspended steel structure, respectively. The number of sets of displacement sensors is the same as the number of layers in the lifting layer 2.

[0053] It is understood that the roof lifting structure 5 is communicatively connected to the aforementioned displacement sensors, forming a linkage control device in conjunction with the controller. The controller can communicate with the displacement sensors and the power lifting equipment via a network for data communication or interaction. The controller has signal processing capabilities, enabling it to process the information transmitted by the force and displacement sensors and issue commands to the power lifting equipment, controlling it to perform corresponding actions. For example, the controller can be a PLC, a host computer, a microcontroller, etc.

[0054] During the pouring of concrete floor slab 6, the bottom-up pouring method is preferred as it is convenient for construction.

[0055] S5. After the concrete floor slab 6 is poured, the lifting layer 2 is finally lifted, so that the stress state of the lifting layer 2 is completely transformed into a tension state. The structural steel columns connecting the lifting layer 2 and the non-lifting layer 3 are then connected, completing the permanent connection between the lifting layer 2 and the non-lifting layer 3. This connection can be achieved by welding or by bolting connecting plates. It should be noted that at this point, the gap between the structural steel columns of the lifting layer 2 and the non-lifting layer 3 completely disappears.

[0056] S6. The roof lifting structure 5 and temporary support system 1 were removed, and the main part of the suspended structure was completed.

[0057] The above construction method can control the vertical deformation difference of the concrete floor slab 6 to always be within the safe range during the construction process, and there is no need to set up post-pouring strips. This optimizes the construction process and significantly shortens the construction period of the suspended main structure of the entire floor.

[0058] In order to effectively reduce the load borne by the temporary support system 1 and its substructure during construction, thereby reducing the amount of steel components used in the temporary support system 1, in step S4, it is ensured that the force borne by the temporary support system 1 does not exceed the preset bearing threshold.

[0059] The load-bearing threshold is the allowable force transmitted to the temporary support system 1, provided that the substructure of the temporary support system 1 and the temporary support system 1 meet the standards and design requirements. The load-bearing threshold is also obtained through construction simulation analysis.

[0060] In this embodiment, the force borne by the temporary support system 1 is obtained through a force sensor. Before constructing the suspended steel structure, a force sensor is installed on the temporary support system 1. The force sensor is also connected to the controller and can provide real-time feedback on the pressure transmitted from the suspended structure above, which is the force borne by the temporary support system 1.

[0061] By lifting the lifting layer 2, part of the force that originally needed to be borne by the temporary support system 1 is transferred to the roof steel truss 4 by the roof lifting structure 5. Under the same suspended structure volume, the force that the temporary support system 1 needs to bear is reduced, and the amount of temporary support system 1 used is reduced.

[0062] Furthermore, in step S4, when lifting the lifting layer 2, the roof lifting structure 5 stops lifting when the vertical deformation difference of the lifting layer 2 and the force borne by the temporary support system 1 reach the preset control median value. The control median value refers to the vertical deformation difference and the force borne by the temporary support system 1 that need to be achieved after each lifting, provided that the deformation threshold and bearing capacity threshold are not exceeded after pouring p (1≤p≤n) layers of concrete floor slab 6. Setting the control median value can provide a certain buffer time for concrete pouring, eliminating the need to lift the lifting layer 2 in real time, and at the same time, it can determine the closing time of the roof lifting structure 5.

[0063] It is important to note that the control median value is not unique; different construction stages can have different control medians. For example, during the pouring of concrete floor slab 6, the higher the floor being poured, the smaller the control median value can be set. This helps avoid excessive deformation during the one-time lifting process in step S5 when the stress state transitions. It is understandable that a control median value can also be set after the unloading of non-lifting layer 3 and before the pouring of concrete floor slab 6. If the vertical deformation difference of lifting layer 2 and the force required to be borne by temporary support system 1 exceed the deformation threshold and bearing capacity threshold, lifting layer 2 also needs to be lifted to ensure that the vertical deformation difference of lifting layer 2 and the force required to be borne by temporary support system 1 reach the control median value for that stage.

[0064] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A construction method for controlling cracking of a suspended structural concrete floor slab, characterized by, Includes the following steps: Construction temporary support system (1) and core tube (7), wherein the core tube (7) is located at the center of the temporary support system (1); Based on the temporary support system (1), a suspended steel structure and a roof steel truss (4) are constructed around the core tube (7). The suspended steel structure includes a lifting layer (2) supported on the temporary support system (1) and a non-lifting layer (3) set under the roof steel truss (4). There is a gap between the lifting layer (2) and the non-lifting layer (3). A roof lifting structure (5) is installed on the roof steel truss (4) and connected to the lifting layer (2); During the pouring of concrete floor slabs (6), the lifting layer (2) is lifted so that the vertical deformation difference of the lifting layer (2) is less than the preset deformation threshold. After the concrete floor slab (6) is poured, the lifting layer (2) is finally lifted to connect the structural steel column of the lifting layer (2) and the non-lifting layer (3), thus completing the permanent connection between the lifting layer (2) and the non-lifting layer (3); at this time, the gap between the structural steel column of the lifting layer (2) and the non-lifting layer (3) completely disappears. The roof lifting structure (5) and the temporary support system (1) are removed, and the main part of the suspended structure is completed.

2. The construction method for controlling cracking in suspended concrete floor slabs according to claim 1, characterized in that, The construction of the suspended steel structure and the roof steel truss (4) specifically includes the following steps: The suspended steel structure is constructed from bottom to top using the sequential construction method up to the m floor, where n > m > 0, and n is the total number of floors in the suspended structure, and m is a constant. A detachable connecting plate is installed on the structural steel column of the m-th layer of the steel structure. A supporting steel column is installed on the connecting plate. The supporting steel column is detachably connected to the connecting plate. There is a gap between the supporting steel column and the structural steel column of the m-th layer steel structure. The construction of the roof steel truss (4) and the steel structure above the m-th layer continues. With the connecting plate as the boundary, the steel structure below the connecting plate is the lifting layer (2), and the steel structure above the connecting plate is the non-lifting layer (3). The supporting steel column, as the structural steel column of the non-lifting layer (3), can support the roof steel truss (4). Remove the connecting plate to separate the lifting layer (2) and the non-lifting layer (3).

3. The construction method for controlling cracking in suspended concrete floor slabs according to claim 2, characterized in that, The non-lifting layer (3) is constructed using the reverse construction method.

4. The construction method for controlling cracking in suspended concrete floor slabs according to claim 2, characterized in that, 3≥nm>0.

5. The construction method for controlling cracking in suspended concrete floor slabs according to claim 1, characterized in that, When the concrete floor slab (6) is poured, the force borne by the temporary support system (1) shall not exceed the preset bearing threshold.

6. The construction method for controlling cracking in suspended concrete floor slabs according to claim 5, characterized in that, Before constructing the suspended steel structure, a force sensor is installed on top of the temporary support system (1).

7. The construction method for controlling cracking in suspended concrete floor slabs according to claim 5, characterized in that, During the pouring of the concrete floor slab (6), when the lifting layer (2) is lifted, the roof lifting structure (5) stops lifting when the vertical deformation difference of the lifting layer (2) and the force borne by the temporary support system (1) reach the preset control median value. The control median value is less than the bearing threshold and the deformation threshold.

8. The construction method for controlling cracking in suspended concrete floor slabs according to claim 1, characterized in that, During the construction of the suspended steel structure, multiple displacement sensors are installed on the suspended steel structure, and the multiple displacement sensors can measure the vertical deformation difference of the suspended steel structure.

9. The construction method for controlling cracking in suspended concrete floor slabs according to any one of claims 1-8, characterized in that, The concrete floor slab (6) is poured from bottom to top.

10. The construction method for controlling cracking in suspended concrete floor slabs according to claim 1, characterized in that, The roof lifting structure (5) is connected to the top layer of the lifting layer (2).

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