A construction method of a self-supporting assembled monolithic laminated slab

Abstract

The present application relates to a kind of construction methods of supporting-free assembly monolithic laminated slab, belong to building construction technical field.The following steps are included: S1: measurement positioning;S2: construction simulation, according to the distribution position of reference area and extension area, the hoisting construction sequence of each laminated slab is simulated, according to the simulation result and the size of each area, the laminated slab prefabrication processing information with corresponding area adaptation as reference is generated, and the installation sequence of the laminated slab in each construction area is determined according to the laminated slab of corresponding area adaptive size, and the installation sequence is gradually constructed from reference area to periphery;S3: the determination of hoisting area and construction sequence;S4: preparation before construction;S5: laminated slab hoisting;S6: multiple laminated slab installation;S7: concrete pouring;S8: quality inspection and acceptance.The present application solves the problems of traditional prefabricated laminated slab, such as the need for truss reinforcement, large thickness, the need for a large number of temporary support, and large amount of on-site wet work.

Description

Technical Field

[0001] This invention belongs to the field of building construction technology, and specifically relates to a construction method for an unsupported assembled monolithic composite slab. Background Technology

[0002] With the development of construction technology, the country is vigorously promoting prefabricated monolithic structures to accelerate construction speed, save construction costs and resources, improve construction quality, and ensure good structural integrity. Currently, prefabricated monolithic structures mostly use composite floor slabs. A certain thickness of floor slab is prefabricated, and after on-site installation, the remaining floor slab is cast in, forming a prefabricated monolithic structure. This gives the floor slab the overall performance of a cast-in-place structure. The minimum thickness of the prefabricated base slab must not be less than 60 mm. At the same time, to ensure an effective bonding interface between the cast-in-place concrete layer and the prefabricated layer, the minimum thickness of the cast-in-place layer is also stipulated to be no less than 60 mm. Although the precast base slab has been manufactured in the factory, the binding of the surface reinforcement, the laying of the pipeline pre-embedded boxes, and the grouting of the grouting material still need to be completed on the construction site. Therefore, in order to ensure the smooth flow of pipelines, the construction workers need to carry out a lot of grooving and drilling operations on the surface of the precast base slab. After deducting the thickness of the reinforcement protective layer, the traditional 60 mm thickness often makes it difficult to meet the technical requirements for pipeline layout. Therefore, the total thickness of the entire floor slab after pouring is usually 130 mm.

[0003] Because the precast layer of traditional precast composite slabs is relatively thin, its bending stiffness is relatively limited. Under the action of its own weight and construction loads during the construction phase, the bending moment reaches its peak at mid-span and gradually decreases to zero at the ends. This internal force distribution characteristic determines that the precast layer can only bear limited bending stress during the construction phase. To compensate for the insufficient stiffness of the precast layer, the conventional practice is to set truss reinforcement under the precast base slab. The upper and lower chords of the truss serve as the surface reinforcement and bottom reinforcement, respectively, while the web members enhance the overall stiffness of the precast layer. However, the web members of the truss reinforcement do not participate in the structural stress during the floor slab's service phase; they only play a temporary supporting role to enhance stiffness during the construction phase. In addition, traditional methods require the erection of a large number of temporary supports, which not only consumes a large amount of steel pipes, fasteners, and other reusable materials, generating considerable rental costs and installation and dismantling labor costs, but more importantly, the setting of the support system severely hinders cross-operations in the lower space, making it difficult to achieve simultaneous construction on multiple floors, and seriously restricting the flexibility and overall efficiency of construction organization. On the other hand, the removal of temporary supports can only be carried out after the poured concrete has reached a certain strength. This waiting period means that the floor slab cannot be put into use immediately after pouring, resulting in a long construction interval and further extending the overall construction period. Therefore, traditional composite slabs have problems such as the need for truss reinforcement, large slab thickness, a large number of temporary supports, and a large amount of on-site wet work during construction. Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, this invention provides a construction method for an unsupported prefabricated composite slab, which solves the problems of traditional prefabricated composite slabs requiring truss reinforcement, large slab thickness, a large number of temporary supports, and a large amount of on-site wet work.

[0005] The objective of this invention can be achieved through the following technical solution: a construction method for an unsupported assembled monolithic composite slab, comprising the following steps: S1: Measurement and positioning. The size of the composite slab construction area, the position of the steel beams and the position of the supporting walls are measured and calibrated. Based on the coordinates of the steel beams and the supporting walls, all relative steel beams and steel beams with a span of less than or equal to 3.2m are divided into relative boundaries of the construction area. The area where the core tube and the shear wall are connected is divided into the reference area. The construction area is divided into multiple extension areas from near to far based on the relative boundaries and the reference area. S2: Construction simulation. Based on the distribution of the reference area and the expansion area, the hoisting construction sequence of each composite slab is simulated. Based on the simulation results and the size of each area, the prefabrication information of the composite slab with the corresponding area adaptation as the reference is generated. The installation sequence of the composite slab in each construction area is determined according to the composite slab with the corresponding area adaptation size. The installation sequence is carried out step by step from the reference area to the surrounding area. The plan layout of each composite slab consists of a central area and a surrounding area. The central area of ​​the composite slab is a special prefabricated slab with a thickness of 120mm. The width of the central area is 50% to 70% of the short span of the reference area. The surrounding area is composed of a prefabricated layer of partial thickness. S3: Determining the hoisting area and construction sequence: The hoisting sequence of the hoisting area is determined based on the installation sequence of the composite slabs and the size and weight data of the produced composite slabs. S4: Before construction, clean up debris and oil stains in the construction area, and install the magnetic pressure irons in the predetermined positions on the steel beams at both ends of the construction area. S5: Composite slab hoisting. The composite slabs are hoisted according to the preset construction sequence and guided and positioned by magnetic clamps. S6: Installation of multiple composite slabs. The composite slabs are hoisted to the preset positions in sequence according to the construction order, so that the installed composite slabs form a simple support, and a 300mm~500mm closing area is reserved between adjacent composite slabs. S7: Concrete pouring. Install the formwork in the post-pouring strip and closure area. Then, tie additional steel bars in the post-pouring strip concrete layer in the closure area and around the composite slab and pour concrete with a strength grade one grade higher than that of the precast layer concrete. After compaction, cure. S8: Quality inspection and acceptance. The installed composite slabs are inspected for positional deviation, elevation deviation, joint quality, and welding quality. The inspection results are entered into the digital integrated collaborative platform to form a quality traceability file.

[0006] As a preferred technical solution of the present invention, in step S1, the digital integrated collaborative platform obtains the accurate distribution area of the extended area according to the measurement data; in step S2, the digital integrated collaborative platform simulates the construction sequence to obtain accurate prefabrication processing information of laminated plates with different sizes.

[0007] As a preferred technical solution of the present invention, in step S3, the reinforcement embedded parts are buried at the predetermined position at the bottom of the laminated plate during the factory prefabrication stage, and in step S6, after the laminated plate hoisting is completed, the reinforcement embedded parts are welded and fixed to the top of the steel beam.

[0008] As a preferred technical solution of the present invention, in step S3, the prefabrication mold of the laminated plate is adjusted to a "return" shaped upper and lower layer stepped combined mold according to the prefabrication processing information, and pipelines are embedded in the upper layer mold.

[0009] As a preferred technical solution of the present invention, in step S7, the additional steel bars tied in the post-cast strip are composed of transverse lapped steel bars and longitudinal distributed steel bars, and the lap length of the transverse lapped steel bars is 1.6 times the anchorage length.

[0010] As a preferred technical solution of the present invention, in step S6, when the simple support is supported on both sides, the construction span of the laminated plate is 3.2 m, and the width of the middle area of the laminated plate is 70% of the short-span of the reference area; when the simple support is supported on four sides, the construction span of the laminated plate is 3.6 m, and the width of the middle area of the laminated plate is 50% of the short-span of the reference area.

[0011] As a preferred technical solution of the present invention, in step S2, the digital integrated collaborative platform establishes a collaborative design module, a production management module and a construction management module through BIM technology to enable the entire construction sequence to be digitally collaboratively constructed.

[0012] As a preferred technical solution of the present invention, in step S7, before the formwork suspension installation, the contact surface of the laminated plate is cleaned, and a release agent is applied and double-sided adhesive strips are pasted at the end positions of the formwork.

[0013] As a preferred technical solution of the present invention, in step S4, shear studs are arranged on the upper flange surface of the steel beam, and in step S6, the shear studs are lap-connected with the additional steel bars.

[0014] The beneficial effects of this invention are as follows: by combining full-thickness prefabrication design and BIM digital collaborative management, the technical defects of traditional prefabricated composite slabs, such as the need to set truss reinforcement, large slab thickness, need for a large number of temporary supports, and large amount of on-site wet work, are solved. This invention realizes the unsupported construction of assembled integral composite slabs, thereby accelerating the construction speed, reducing the construction cost, improving the construction efficiency, and ensuring the installation quality. Attached Figure Description

[0015] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0016] Figure 1 This is a schematic diagram of the construction process of the present invention. Detailed Implementation

[0017] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0018] Please see Figure 1 This embodiment provides a construction method for an unsupported assembled monolithic composite slab, including the following steps: S1: Measurement and Positioning. Construction personnel, carrying laser rangefinders and total stations, enter the floor to be constructed to measure and mark the size of the composite slab construction area, the position of the steel beams, and the position of the supporting walls to obtain accurate coordinates and elevations. All parallel and opposing steel beams, as well as the relative boundaries formed between the steel beams and the supporting walls, are identified. The vertical distance (i.e., the short span) between each pair of relative boundaries is calculated. Relative boundaries with a short span ≤ 3.2m are marked as the boundaries of the effective construction area. The construction area is divided into multiple expansion areas from near to far based on the relative boundaries and the reference area. The installation position of each composite slab is accurately measured and marked, and the installation edge line of the composite slab is marked on the upper flange of the steel beam. The construction site is divided into a reference zone and several extension zones. Since unsupported construction eliminates the need for bottom supports, a unified bottom elevation reference is lost. Therefore, a reference point must be found within the structure itself. The reference zone is selected from areas near the core tube or connected to shear walls. This is because shear walls and the core tube are the most stable vertical components in the structure, providing the most reliable elevation and planar position reference for the installation of the first slab. Therefore, before hoisting, magnetic clamps must be precisely installed on the steel beams in this area as the coordinate origin for positioning all subsequent slabs. After establishing the reference zone, the work expands rapidly outwards, forming a continuous flow operation. Because unsupported construction is used, there is no need to consider symmetrical loading to prevent support instability at this stage; all slabs can be hoisted in any order. Therefore, the zoning logic is to divide the remaining floor slabs into several extension zones based on the tower crane's working radius and lifting capacity. Priority should be given to hoisting tower cranes in areas with good coverage and moderate component weight to maximize tower crane efficiency. The construction sequence strategy should combine methods of starting from the farthest point and proceeding from the nearthest point to the farthest point. Within the same expansion area, the principle of starting from the farthest point facilitates subsequent personnel operations and material transportation. However, from an overall process perspective, the construction sequence expands from the base area outwards. S2: Construction simulation. Based on the distribution of the baseline area and the expansion area, the hoisting construction sequence of each composite slab is simulated. Based on the simulation results and the size of each area, composite slab prefabrication information with the corresponding area adaptation as the benchmark is generated. The installation sequence of the composite slab in each construction area is determined according to the composite slab with the appropriate size for the corresponding area. The installation sequence proceeds from the baseline area to the surrounding areas. The plan layout of each composite slab consists of a central area and a surrounding area. The central area of ​​the composite slab is a specialized prefabricated layer with a floor slab thickness of 120mm. The width of the central area is 50% to 70% of the short span of the baseline area. The surrounding area is composed of prefabricated layers of partial thickness. The production plan is generated by reverse calculation. Based on the actual span data of each construction area measured by S1, the bearing capacity, crack width and deflection of the construction stage (simply supported state) were checked according to the "Code for Design of Concrete Structures" (GB50010). With "no temporary support" as the constraint, the minimum full thickness of the precast slab required in the middle area of ​​each span was determined by reverse calculation. When the short span is ≤3.2m, the full thickness of the precast slab in the middle area is 50% to 70% and the thickness is 120mm, which can meet the stress requirements of both the construction stage and the service stage. However, when the full thickness of the middle area is <50%, the high stress area in the middle of the span is not completely covered, which will cause the composite slab to crack during construction. When the span is >70%, the full thickness area is too large, the self-weight increases significantly, and the hoisting efficiency is affected. S3: Determining the hoisting area and construction sequence: Based on the installation sequence of the composite slabs and the dimensions and weight data of the produced composite slabs, determine the hoisting area and hoisting sequence, and determine the optimal hoisting path based on the hoisting sequence; S4: Before construction, the construction personnel clean the floating rust, welding slag and oil stains on the upper flange of the steel beam to ensure that the surface is flat and clean. Then, the magnetic clamp is installed in the predetermined position. The magnetic clamp is attracted to the upper flange of the steel beam by magnetic force to form a precise limiting boundary. S5: Composite slab hoisting. The tower crane lifts the composite slab at four points and hoists it piece by piece according to the construction sequence determined in S2. When it is hoisted to 300mm above the installation position, the operator pulls the guy rope to pull the slab and uses the magnetic pressure iron to guide the slab to automatically fall into place along the limit boundary. S6: Multiple composite slabs are installed. The composite slabs are hoisted to the preset positions in sequence according to the construction order so that the installed composite slabs form a simple support. A 300mm~500mm closing area is reserved between two adjacent composite slabs so that the installed composite slabs form a simple support. That is, the two ends of the slab rest on the steel beams, and the middle relies on the rigidity of its own 120mm full-thickness prefabricated area to bear the load. Because of the unsupported construction method, all post-cast strip formwork is constructed using suspended formwork. Therefore, its construction quality directly affects structural safety. To facilitate suspended formwork installation, the closure zone of the suspended formwork provides pre-fixed composite plates on both sides as support points, making it easier for workers to operate. Simultaneously, to ensure the quality of the joints, placing crucial joints like post-cast strips last allows for focused work on key processes such as rebar connections and formwork sealing, avoiding disturbance from subsequent hoisting operations. Furthermore, to meet the minimum working surface requirements for suspended formwork installation and the operational space for the vibrator during concrete pouring, the width of the closure zone must be 300mm. However, to avoid increased shrinkage and cracking risk due to excessively wide closure zones after concrete pouring, the width of the closure zone must be less than 500mm. The closure zone is selected for post-cast strip areas, areas with large spans, or areas containing irregularly shaped slabs.

[0019] S7: Concrete pouring, install hanging formwork in the closure area and position, and then tie additional reinforcing bars in the closure area and post-pouring strip position. The additional reinforcing bars consist of transverse lapped reinforcing bars and longitudinal distributed reinforcing bars. The hanging formwork is fixed to the installed composite slab or steel beam by the suspension components, and does not contact the lower ground at all. Then pour micro-expansion concrete one grade higher than the precast layer, vibrate it to compact it, and then cure it. S8: Quality inspection and acceptance. Conduct a full inspection of the positional deviation, elevation deviation, joint quality, and welding quality of the installed composite slabs. The results are entered into the digital integrated collaborative platform to form a quality traceability archive.

[0020] Because the precast layer of traditional precast composite slabs is relatively thin, its bending stiffness is relatively limited. Under the action of self-weight and construction load during the construction stage, the bending moment at the mid-span reaches its peak, and the bending moment at the ends gradually decreases to zero. Therefore, due to the weak tensile strength of concrete, it is easy for the mid-span to bend and generate tensile force under the action of the self-weight of the composite slab and construction load, causing the composite slab to crack. However, since the bending moment at both ends is zero, it will not be subjected to bending and generate tensile force, thus preventing the composite slab from cracking. Therefore, this internal force distribution characteristic means that the precast layer can only bear limited bending stress during the construction stage. Therefore, during the construction of composite slabs, a large number of temporary supports need to be installed on the lower layer to ensure that the composite slabs have sufficient support during construction, thereby preventing cracking. At the same time, the need to erect a large number of temporary supports on the lower layer not only increases the construction process and cost, but also occupies the lower layer space and hinders the cross-operation of mechanical and electrical, fire protection, and masonry processes. In addition, the existence of the temporary support system means that the construction process must be carried out in the order of "erecting supports - hanging slabs - pouring - curing - dismantling supports", which makes it impossible to overlap the processes and thus affects the construction efficiency.

[0021] Therefore, by adopting full-thickness prefabrication design and dividing the construction area to determine the construction sequence of composite slabs of different shapes, the unsupported construction process can be realized in sequence. This solves the technical defects of traditional prefabricated composite slabs, such as the need to set truss reinforcement, large slab thickness, need for a large number of temporary supports, and large amount of on-site wet work. It realizes the unsupported construction of assembled integral composite slabs, which speeds up construction, reduces construction costs, improves construction efficiency, and ensures installation quality.

[0022] Since the production and construction of the laminated slab are carried out synchronously and out of alignment, in order to ensure that there is a lack of unified elevation and position benchmarks during the construction process, cumulative errors lead to the inability to close finally, and position conflicts are discovered only after each plate is independently positioned. When demolition and reconstruction are required, the lifting sequence does not match the order of component arrival at the site, resulting in the backlog of on-site components, which in turn affects the construction efficiency. In this embodiment, in step S1, the digital integrated collaboration platform obtains the accurate distribution area of the extended area based on the measurement data; in step S2, the digital integrated collaboration platform simulates the construction sequence to obtain accurate prefabrication processing information for laminated slabs of different sizes; the digital integrated collaboration platform automatically generates a three-dimensional model based on the X, Y, and Z coordinate data of the steel beams; in the three-dimensional model, all pairs of steel beams that are parallel to each other and arranged oppositely are automatically identified, and the vertical distance between each pair of steel beams is calculated; the effective boundaries with a short-span ≤ 3.2 m are automatically screened out and marked on the three-dimensional model; taking the marked core tube or shear wall area as the reference area, the extended area is automatically divided step by step according to the principle of "from near to far", and the boundary coordinates and elevation data of each area are output. Then, taking "expanding from the reference area to the surroundings" as the constraint condition, a preliminary lifting sequence is automatically generated; and according to the short-span of each area, the width of the middle area of each laminated slab is automatically calculated at a ratio of 50% - 70%; the standard mold library is called for matching to generate the optimal mold layout plan; the prefabrication processing information (dimensions, reinforcement, position of embedded parts, etc.) of each laminated slab is output, avoiding data loss or errors in the manual conversion link, and improving the accuracy of area division and the accuracy of construction simulation.

[0023] Because the traditional laminated slab mold has a fixed size and different molds are required for different specifications of plates, while the construction of the laminated slab in this invention needs to produce "thin around and thick in the middle" special-shaped laminated slabs of different size specifications according to the construction steps. Therefore, in order to reduce the mold production cost and production cycle, in this embodiment, in step S3, the digital integrated collaboration platform generates a stepped combined mold layout plan for the upper and lower layers according to the measurement results, and at the same time embeds pipelines in the upper-layer mold. The digital integrated collaboration platform generates the mold layout plan according to the measurement results, and the upper-layer mold and the lower-layer mold are arranged in a stepped "hui" shape. The lower-layer mold corresponds to the "thin around" area of the plate, and the upper-layer mold corresponds to the "thick in the middle" area of the plate. The upper and lower layer molds are fixed by bolt connection, and bolt holes are opened on the mold according to common moduli. The mold size is changed by adjusting the position of the bolts at different hole positions. During the production process, after the workers complete the mold combination according to the mold layout plan, stress reinforcement bars are tied in the upper-layer mold (corresponding to the thick middle area), and structural reinforcement bars are arranged in the lower-layer mold (corresponding to the thin around area). At the same time, electric conduits, junction boxes, and sleeves are embedded at the predetermined positions, avoiding on-site grooving. At the same time, mold matching through the BIM platform reduces the amount of mold production and lowers the production cost.

[0024] Because the 300mm~500mm closure zone between two adjacent composite slabs requires post-cast concrete, the reinforcing bars in the post-cast concrete need to form a reliable connection with the reserved reinforcing bars of the precast slabs on both sides. If the lap length of the additional reinforcing bars in the post-cast strip is insufficient or the connection is unreliable, the post-cast strip will become a weak link in the structure and will fail first under earthquake action. Moreover, the slabs cannot form an integral load-bearing structure, reducing the continuity and stiffness of the floor slab. At the same time, cracks are prone to appear at the joints, affecting waterproofing performance and durability. Therefore, in order to ensure the structural stability of the closure zone, in this embodiment, in step S7, the additional reinforcing bars tied to the post-cast strip consist of transverse lapped reinforcing bars and longitudinal distributed reinforcing bars. The lap length of the transverse lapped reinforcing bars is 1.6 times the anchorage length. Additional reinforcing bars enable adjacent composite slabs to form a unified whole in the closure zone. Then, a higher grade of micro-expansion concrete ensures a tight interlock between the post-cast zone and the precast zone. Therefore, when a load is generated, it can be transferred from one slab to another through the additional reinforcing bars, allowing the post-cast strip and the precast slab to form a unified force-bearing structure, ensuring the structural stability of the closure zone. The force transfer of lap splices is essentially "anchoring," but the two lapped reinforcing bars are tightly attached together, resulting in insufficient concrete wrapping in the middle area. This makes the bond strength less than that of a single reinforcing bar. Therefore, to avoid this missing bond strength, all additional reinforcing bars are lapped with a joint area percentage of 100% as a benchmark, making the lap length 1.6 times the anchorage length to compensate for the loss of bond strength during lap splicing.

[0025] To ensure the load-bearing capacity of the composite slab during construction and to prevent cracking or excessive deflection during the construction phase, in this embodiment, in step S6, when the simply supported slab is supported on both sides, the construction span of the composite slab is 3.2m, and the width of the central region of the composite slab is 70% of the short span of the reference area. When the simply supported slab is supported on all four sides, the construction span of the composite slab is 3.6m, and the width of the central region of the composite slab is 50% of the short span of the reference area. When the composite slab is supported on all four sides, the stress state of the slab is better, the load is transferred to all four sides, and the mid-span bending moment is reduced, hence the span is 3.6m. When the composite slab is supported on both sides, the slab is equivalent to a one-way slab, the load is only transferred to both sides, and the mid-span bending moment is larger, hence the span is limited to 3.2m. The above span values ​​are safety critical values ​​determined through two-stage verification under the condition of 120mm full thickness prefabrication in the central region.

[0026] In the traditional model, design, production, and construction operate independently, resulting in poor information flow. This leads to errors in design drawings being discovered only during the construction phase, requiring changes and rework. Production plans and construction schedules are mismatched, with components arriving too early causing stockpiling or too late causing idle time. On-site problems cannot be promptly reported to the design and production stages, leading to recurring issues. Therefore, in this embodiment, in step S2, the digital integrated collaborative platform uses BIM technology to establish collaborative design, production management, and construction management modules, enabling digital collaborative construction throughout the entire construction process. By utilizing the digital integrated collaborative platform for overall modeling of floor slabs and structures, the platform optimizes the rebar connections between floor slabs, between floor slabs and cast-in-place slabs, and between floor slabs and wall panels. Optimization includes the arrangement and direction of rebar, anchorage length, lap position, and shear stud placement. Simultaneously, 3D modeling is used to check for rebar collisions, identifying mutual interference and collisions between rebars, between rebars and studs, and between rebars and pipelines, allowing for timely design adjustments. Based on the 3D model, information from various disciplines is integrated to establish a coordination model for architecture, structure, and MEP (Mechanical, Electrical, and Plumbing) to resolve cross-conflicts between pipelines and rebars, and between pipelines themselves. In the construction management module, BIM4D construction simulation is first conducted, and the installation approach for the prefabricated composite slab is determined based on actual site conditions. Combining the model built during the detailed design phase, BIM4D technology is used to simulate the hoisting path, hoisting point settings, placement sequence, and construction time of the floor slab. This allows for the early detection of potential spatial conflicts, hoisting path obstacles, and component collisions during construction, providing visual guidance for on-site construction.

[0027] If the contact surfaces are not cleaned and sealed before the formwork is installed, gaps may appear between the formwork and the edge of the composite slab. During pouring, cement slurry may seep out from these gaps, forming "rotten roots" or "sand lines," affecting the appearance quality. Furthermore, during demolding, the concrete may stick to the formwork, damaging the surface of the poured concrete. Therefore, in this embodiment, in step S7, before the formwork is installed, the contact surfaces of the composite slab are cleaned, and a release agent is applied. At the same time, double-sided adhesive strips are pasted at the ends of the formwork. By cleaning the contact surfaces, the impact of impurities on the fit between the formwork and the composite slab is reduced, lowering the risk of grout leakage. After cleaning, a release agent is evenly applied to the contact surfaces and the surface of the formwork. The release agent forms a release film to prevent the concrete from sticking to the formwork. Then, by continuously pasting double-sided adhesive strips at the contact points between the formwork and the edge of the composite slab, the double-sided adhesive strips form an elastic sealing layer between the formwork and the composite slab. Under the lateral pressure of the concrete, the double-sided adhesive strips are pressed tightly, effectively sealing the gaps and preventing cement slurry from leaking out.

[0028] To avoid a lack of shear-resistant connection between the composite slab and the steel beam, which could lead to the composite slab slipping on the steel beam under horizontal loads and the inability of the floor slab and steel beam to form a combined beam effect, thus reducing the load-bearing capacity, in this embodiment, shear studs are installed on the upper flange surface of the steel beam in step S4, and in step S6, the shear studs are lapped with additional reinforcing bars. After the composite slab is hoisted into place, the pre-drilled holes or grooves on the bottom of the slab fit precisely over the shear studs. At this point, the reinforcing embedded parts at the bottom of the slab are welded and fixed to the steel beam. During the pouring of concrete in the closure zone and post-cast strip, the shear studs are encased in the concrete. At the same time, the transverse lapped reinforcement in the additional reinforcement in the post-cast strip forms a lap connection with the head of the shear stud. When the composite slab is subjected to horizontal force, the composite slab causes the concrete to tend to displace. The concrete pushes the head of the stud, and the stud transmits the force to the steel beam. The lap connection between the additional reinforcement and the head of the stud extends the shear resistance from the stud point to the entire post-cast strip area, thereby providing a reliable shear connection between the steel beam and the composite slab.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A construction method for an unsupported assembled monolithic composite slab, characterized in that: It includes the following steps: S1: Measurement and positioning. Measure and calibrate the size of the construction area of the composite slab, the positions of the steel beams and the supporting walls. According to the coordinates of the steel beams and the supporting walls, divide the spans less than or equal to 3.2m between all relative steel beams and between steel beams and supporting walls into the relative boundaries of each construction area, and divide the area where the core tube is connected to the shear wall into the reference area. The construction areas are divided into multiple extended areas based on the reference area from near to far according to the divided relative boundaries. S2: Construction simulation. According to the distribution positions of the reference area and the extended areas, simulate the hoisting construction sequence of each composite slab. Generate the prefabrication processing information of the composite slab based on the corresponding area adaptation according to the simulation results and the sizes of each area. Determine the installation sequence of the composite slab in each construction area according to the composite slab adapted to the size of the corresponding area. The installation sequence is gradually constructed from the reference area to the surrounding. The plane layout of each composite slab consists of a central area and a peripheral area. The central area of the composite slab is a specialized prefabrication with a floor slab thickness of 120mm, and the width of the central area is 50% to 70% of the short-span of the reference area. The peripheral area consists of partial thickness prefabrication layers. S3: Determination of the hoisting area and construction sequence. Determine the hoisting sequence of the hoisting area according to the installation sequence of the composite slab and the size and weight data of the produced composite slab. S4: Preparation before construction. Clean the sundries and oil stains in the construction area, and install magnetic pressing irons at the predetermined positions on the steel beams at both ends of the construction area. S5: Hoisting of the composite slab. Lift the composite slab and hoist it according to the preset construction sequence and guide and position it through the magnetic pressing iron. S6: Installation of multiple composite slabs. Hoist the composite slabs to the preset positions in sequence according to the construction sequence, so that the installed composite slabs form simply supported supports, and a closing area of 300mm - 500mm is reserved between adjacent two composite slabs. S7: Concrete pouring. Install formwork supports in the post-cast strip and the closing area, then bind additional steel bars in the post-cast strip concrete layers in the closing area and around the composite slab, and pour concrete with a strength grade one level higher than that of the prefabrication layer. After vibrating and compacting, carry out maintenance.

2. The construction method of an unsupported assembled integral composite slab according to claim 1, characterized in that: S8: Quality inspection and acceptance. Inspect the position deviation, elevation deviation, joint quality and welding quality of the installed composite slab. Enter the inspection results into the digital integrated collaborative platform to form a quality traceability file.

3. The construction method of an unsupported assembled integral composite slab according to claim 1, characterized in that: In step S1, the digital integrated collaborative platform obtains the accurate distribution area of the extended area according to the measurement data; in step S2, the digital integrated collaborative platform simulates the construction sequence to obtain accurate prefabrication processing information of composite slabs with different sizes.

4. The construction method of an unsupported assembled integral composite slab according to claim 1, characterized in that: In step S3, the reinforcement embedded parts are buried at the predetermined positions at the bottom of the composite slab during the factory prefabrication stage. In step S6, after the hoisting of the composite slab is completed, the reinforcement embedded parts are welded and fixed to the top of the steel beam.

5. The construction method of an unsupported assembled integral composite slab according to claim 1, characterized in that: In step S, the prefabrication mold of the composite slab is adjusted to a "return" shaped upper and lower layer stepped combined mold according to the prefabrication processing information, and pipelines are embedded in the upper layer mold. In step S7, the additional steel bars tied in the post-cast strip are composed of transverse lapped steel bars and longitudinal distribution steel bars, and the lap length of the transverse lapped steel bars is 1.6 times the anchorage length.

6. The construction method of an unsupported assembled integral composite slab according to claim 1, characterized in that: In step S6, when the simply supported slab is supported on both sides, the construction span of the composite slab is 3.2m, and the width of the middle area of ​​the composite slab is 70% of the short span of the reference area. When the simply supported slab is supported on all four sides, the construction span of the composite slab is 3.6m, and the width of the middle area of ​​the composite slab is 50% of the short span of the reference area.

7. The construction method of an unsupported assembled integral composite slab according to claim 1, characterized in that: In step S2, the digital integrated collaborative platform establishes collaborative design, production management and construction management modules through BIM technology, enabling the entire construction process to be digitally collaboratively constructed.

8. The construction method of an unsupported assembled integral composite slab according to claim 1, characterized in that: In step S7, before installing the hanging mold, the contact surfaces of the composite plate are cleaned and a release agent is applied. At the same time, double-sided adhesive strips are pasted at the ends of the template.

9. The construction method of an unsupported assembled integral composite slab according to claim 1, characterized in that: In step S4, shear studs are provided on the upper flange surface of the steel beam. In step S6, the shear studs are lapped with additional reinforcing bars.

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