A construction method for ultra-long cantilever formwork

Abstract

This invention discloses a construction method for ultra-long cantilever formwork, comprising the following steps: Step 1, pre-embedding: pre-embedding several sets of inclined top mounting components on the Nth floor slab and several sets of cantilever main beam mounting components on the N+th floor slab; Step 2, main frame erection: installing a cantilever main beam on each set of cantilever main beam mounting components on the N+th floor slab, installing an inclined beam below the cantilever main beam, and installing the inclined top mounting components on the Nth floor slab below the inclined beam to form an ultra-long cantilever main frame; Step 3, secondary frame erection: erecting several sets of secondary beams parallel above the main frame, erecting uprights above the secondary beams, and erecting ground-level bracing vertically from multiple uprights to form a secondary frame; This invention, by installing the cantilever main beam on the cantilever main beam mounting components, wherein the cantilever extends from the slab surface, strengthens the connection between the cantilever and the slab surface, thereby enabling the erection of ultra-long cantilever formwork while maintaining the treatment of the connection area and a benign pressure relief environment, thus improving the safety factor during the construction of ultra-long cantilever eaves.

Description

Technical Field

[0001] This invention is a construction method for ultra-long cantilever formwork, belonging to the field of cantilever formwork technology. Background Technology

[0002] With the booming development of the construction industry and the improvement of architectural design technology, more and more individual buildings are gradually developing towards personalization and irregularity. Landmark buildings are generally characterized by unique shapes and high construction difficulty, and most of these buildings adopt eaves design at the top.

[0003] An eaves refers to the part of the roof (floor) that protrudes beyond the exterior wall. Generally, the protrusion width is no more than 50 centimeters. It is mainly used to facilitate roof drainage and also to protect the exterior wall. However, in modern design, especially in high-rise buildings with eaves, the protrusion width is often greater than 50 centimeters in order to further showcase its uniqueness and shape. Therefore, its construction is more difficult and requires the use of cantilever formwork.

[0004] The existing construction methods for cantilever formwork mostly involve erecting precast cantilever casting formwork and installing plumb lines on the cantilever formwork to increase its load-bearing capacity during casting and reduce stress on the connection points. The cantilever formwork is then cast together with the slab formwork. However, this construction method results in limited connection between the cantilever section and the slab surface, requiring auxiliary plumb lines for pressure support. Consequently, when erecting extra-long cantilever formwork, the connection points are prone to cracking due to excessive pressure, creating safety hazards for the cantilever section. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a construction method for ultra-long cantilever formwork to solve the problems of the existing technology.

[0006] To achieve the above objectives, the present invention provides a method for constructing ultra-long cantilever formwork, comprising:

[0007] Step 1, Pre-embedding: Pre-embed several sets of inclined roof installation parts in the Nth floor slab, and pre-embed several sets of cantilever main beam installation parts in the N+1th floor slab;

[0008] Step 2, main frame erection: Install a cantilever main beam on each set of cantilever main beam installation components on the N+1 floor slab, install an inclined beam under the cantilever main beam, and install the inclined top installation components of the N floor slab below the inclined beam to form an ultra-long cantilever main frame;

[0009] Step 3, Erection of the secondary frame: Several sets of secondary beams are erected parallel above the main frame, uprights are erected above the secondary beams, and ground-level bracing is erected vertically on the multiple uprights to form the secondary frame;

[0010] Step 4, Formwork Monitoring: Erect extra-long pouring formwork on the sub-frame, and set up an observation point in each span of the extra-high slab, and place monitoring brackets;

[0011] Step 5, pouring: Remove the monitoring support and vibrate and pour concrete onto the extra-long pouring formwork.

[0012] As a further improvement, the method of pre-embedding several sets of inclined top mounting components in the Nth floor slab and several sets of cantilever main beam mounting components in the N+1th floor slab includes: the cantilever main beam mounting component is a U-shaped component, the bottom of which needs to penetrate the internal steel bars of the N+th floor slab, the cantilever main beam is inserted into the interior of multiple U-shaped components, and a cover plate is fixedly installed at the open end of the U-shaped component to restrain the cantilever main beam.

[0013] As a further improvement, the method of pre-embedding several sets of inclined top mounting components in the Nth floor slab and several sets of cantilever main beam mounting components in the N+1th floor slab further includes: two hook rods installed below the inclined top mounting components, which are hooked to the internal steel bars of the Nth floor slab, and the inclined beams are inserted into the grooves formed by the flipping of two steel plates above the inclined top mounting components.

[0014] As a further improvement, several grooves are vertically arranged on one side of the groove, and the inclined beam abuts against one of the grooves.

[0015] As a further improvement, the installation of a cantilever main beam on each set of cantilever main beam mounting components on the N+1 floor slab includes: the fixed length of the cantilever main beam is at least 1.25 times the cantilever length.

[0016] The installation of an inclined beam under the cantilever main beam includes: fitting the parallel groove above the inclined beam with the parallelogram protrusion below the cantilever main beam whose inclination direction faces the installation direction of the inclined beam, and welding the inclined beam to the inner side and left and right sides of the inclined beam with angle steel, and fixing the outer side of the inclined beam to the inclined beam protrusion.

[0017] As a further improvement, the installation of an inclined beam under the cantilevered main beam includes: the top of the inclined beam is installed at 3 / 5 of the distance from the cantilevered main beam toward the cantilever end.

[0018] As a further improvement, after the main frame is erected and before the secondary frame is erected, a top-mounting frame needs to be erected on the N-1 floor directly below the inclined beam.

[0019] As a further improvement, the method of erecting a top-mounting frame at the location directly below the inclined beam on the N-1 floor includes: a hook rod at the bottom of the inclined top mounting component partially penetrating the floor slab, and the top-mounting frame being vertically arranged with a radius of 1 to 1.2m around the part through which the hook rod passes.

[0020] As a further improvement, the concrete vibration pouring of the ultra-long casting formwork includes: using a combination of bucket and tower crane hoisting and manual vibration to simultaneously carry out the pouring, and adopting a symmetrical expansion pouring method from the middle to both ends in the ultra-long casting formwork.

[0021] The beneficial effects of this invention are:

[0022] This invention installs the cantilever main beam on the cantilever main beam mounting component and installs an inclined beam at an angle below the cantilever main beam. The bottom of the inclined beam is fixed to the inclined top mounting component in the next adjacent floor. The inclined beam supports the cantilever main beam and also distributes the weight of the cantilever part of the cantilever main beam in the upper floor to the lower floor, thereby greatly increasing the cantilever length of the cantilever main beam.

[0023] The construction process involves welding and erecting secondary beams above the cantilevered main beam, constructing vertical and horizontal supports around these secondary beams, laying extra-long casting formwork, and finally, tying reinforcing bars to the casting formwork to form a casting cavity before pouring concrete in layers. The use of inclined beams for support enhances the load-bearing capacity of the cantilevered formwork during casting and reduces stress at the connection points. The cantilever extends from the slab surface, strengthening the connection between the cantilever and the slab surface, thus allowing for the erection of extra-long cantilevered formwork while maintaining a suitable connection area and a well-ventilated pressure-relief environment, thereby improving the safety factor during the construction of extra-long eaves. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram illustrating the steps of a construction method for an ultra-long cantilever formwork according to the present invention.

[0026] Figure 2 This is a side view of an ultra-long cantilever template according to the present invention.

[0027] Figure 3 This is a top view of an ultra-long cantilevered template according to the present invention.

[0028] Figure 4 This is a top view of an ultra-long cantilevered template according to the present invention.

[0029] Figure 5 This is a schematic diagram of the connection status at the top of the inclined beam.

[0030] Figure 6 This is a schematic diagram of the internal structure at the top of the inclined beam.

[0031] Figure 7 This is a schematic diagram showing the connection status at the bottom of the inclined beam. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] In existing construction methods for cantilever formwork, the vast majority involve erecting precast cantilever casting formwork and installing plumb lines on it to increase its load-bearing capacity during casting and reduce stress at the joints. The cantilever formwork is then cast together with the slab formwork. However, this method results in limited connection between the cantilever section and the slab surface, requiring auxiliary plumb lines for pressure support. Consequently, when erecting extremely long cantilever formwork, the joints are prone to cracking due to excessive pressure, posing a safety hazard. Therefore, to address the aforementioned technical problems, this invention discloses the following technical solution:

[0036] Reference Figure 1-7 As shown, a construction method for ultra-long cantilever formwork includes:

[0037] Step 1, Pre-embedding: Pre-embed several sets of inclined roof installation parts 1 in the Nth floor slab 5, and pre-embed several sets of cantilever main beam installation parts 2 in the N+1th floor slab 6;

[0038] Step 2, Main Frame Erection: Install a cantilever main beam 3 on each set of cantilever main beam mounting components 2 on the N+1 floor slab 6, install a diagonal beam 4 under the cantilever main beam 3, and install the diagonal top mounting component 1 of the Nth floor slab 5 below the diagonal beam 4 to form an ultra-long cantilever main frame; wherein, the diagonal top mounting component 1 corresponds one-to-one with the diagonal beam 4, and each set of cantilever main beam mounting components 2 has several main beam mounting components 2, and the cantilever main beam 3 needs to be embedded in several main beam mounting components 2 in the same set and fixed;

[0039] Step 3, Erection of the sub-frame: Several sets of secondary beams 7 are erected in parallel above the main frame, and steel mesh 73 is laid on the secondary beams 7. Vertical poles 71 are erected above each beam 7 and set around the cantilevered main beam 3. Ground sweeping poles 73 are erected vertically on multiple vertical poles 71 to form the sub-frame.

[0040] Step 4, pouring: Erect an extra-long pouring formwork 8 on the sub-frame and pour concrete into the extra-long pouring formwork by vibration.

[0041] In this embodiment, the cantilever main beam installation component 2 is pre-installed in the N+1 floor slab 6 of the cantilever layer, and the inclined top installation component 1 is installed in the floor below it. This greatly reduces the positioning work when building the ultra-long cantilever formwork. The support components between the upper and lower floors can be accurately connected directly through the corresponding pre-embedded parts, reducing the time cost of measurement and positioning.

[0042] Compared to conventional cantilever formwork construction methods, in this case, the cantilever main beam 3 is first installed on the cantilever main beam mounting component 2, and an inclined beam 4 is installed at an angle below the cantilever main beam 3. The bottom of the inclined beam 4 is fixed to the inclined top mounting component 1 in the next adjacent floor. The inclined beam 4 supports the cantilever main beam 3 and also distributes the weight of the cantilever part of the cantilever main beam 1 in the upper floor to the lower floor, which greatly increases the length of the cantilever part of the cantilever main beam 1. Then, the secondary beam 7 is welded and erected above the cantilever main beam 1, and the uprights 71 and the ground sweeping rods 73 are erected around the secondary beam 7 of the cantilever part. The extra-long casting formwork 8 is then laid. Finally, after the steel bars are tied on the casting formwork to form a casting cavity, the concrete is poured in layers to form an extra-long eaves. During the pouring process of the extra-long casting formwork 8, the support of the cantilever main beam 3 and the assistance of the inclined beam 4 below can provide strong support for the casting cavity, which greatly enhances the stability of the concrete in the cantilever part during the solidification period.

[0043] To accommodate the different length requirements of cantilever sections, when setting the cantilever main beam 3, the fixed length of the cantilever main beam 3 connected to the cantilever main beam mounting component 2 is at least 1.25 times the length of the cantilever section in the air. When the fixed length of the cantilever main beam 3 is less than 1.25 times the length of the cantilever section in the air, the lever point of the cantilever main beam 3 moves backward, and the upward lifting pressure on the fixed part of the cantilever main beam 3 and the cantilever main beam mounting component 2 is greater. However, when the length ratio is equal to or greater than 1.25 times, the lever point of the cantilever main beam 3 moves forward, and when the same pressure is applied to the cantilever section, the upward lifting pressure on the fixed part of the cantilever main beam mounting component 2 is smaller. Therefore, under the same pressure condition, the safety factor can be enhanced by controlling the length ratio, while achieving a longer cantilever length.

[0044] To create a stable oblique support at the bottom of the cantilever main beam 3 and to accommodate adjustments to the length of different cantilever sections, several parallelogram-shaped protrusions 31 are spaced apart below the cantilever main beam 3. A groove matching the parallelogram-shaped protrusions 31 is provided above the oblique beam 4. The groove is closed on three sides, with the side furthest from the floor slab being open. The oblique beam 4 is obliquely abutted against the bottom of the cantilever main beam 3, allowing the parallelogram-shaped protrusions 31 to fit into the groove. During welding, the contact area between the oblique beam 4 and the cantilever main beam 3 is welded, and the parallelogram-shaped protrusions 31 are welded to the oblique beam 4 through the open end of the groove, thus maintaining the oblique beam 4. When beam 4 is under pressure, it can not only maintain the force on the other three sides, but also provide tensile force through the welding surface with the parallelogram protrusion 31. At the same time, the setting of the parallelogram protrusion 31 can effectively improve the safety of the inclined beam 4. Even if there is a problem at the welding point, it can still maintain the stability of its connection. After the parallel groove above the inclined beam and the parallelogram protrusion below the cantilever main beam with the inclined direction facing the installation direction of the inclined beam are fitted together, the inclined beam 4 is fixed to the inclined beam 4 by welding angle steel 32 on the inner side and the left and right sides of the inclined beam. The angle steel 32 is also made of L100×8 angle steel with a length of 50mm, which can further improve the safety factor of the connection between the two.

[0045] In this embodiment, the parallelogram protrusions 31 are spaced 30-50cm apart. The spacing needs to be adjusted adaptively according to the length of the cantilever main beam 3. When the length of the cantilever main beam 3 is less than 6m, the spacing of the parallelogram protrusions 31 is 30cm; when the length of the cantilever main beam 3 is less than 6m-12m, the spacing is 40cm; and when the length of the cantilever main beam 3 is greater than 6m-12m, the spacing is 50cm. This adaptive adjustment based on the different lengths of the cantilever main beam 3 effectively prevents the inclined beam 4 from failing to precisely abut against the pre-set proportional position below the cantilever main beam 3 when adjusting the length of the cantilever end.

[0046] When the distance through the cantilever increases, the connection position between the inclined beam 4 and the cantilever main beam 3 needs to be adjusted. This is done by adjusting the ratio of the fixed length of the cantilever main beam 3 to the suspended cantilever length to 1.25. Furthermore, the top installation position of the inclined beam 4 is located at 3 / 5 of the direction of the cantilever main beam toward the cantilever end. Therefore, the top installation position of the inclined beam 4 and the corresponding parallelogram protrusion 31 are adjusted accordingly.

[0047] Furthermore, after adjusting the distance of the cantilever section, a slight offset occurs in the installation angle between the top of the inclined beam 4 and the corresponding parallelogram protrusion 31. This offset can be effectively reduced by using several first groove strips 33 arranged longitudinally on the inner side of the parallel groove at the top of the inclined beam 4, with the parallelogram protrusion 31 engaging within the first groove strips 33, followed by the aforementioned welding fixation. In this embodiment, six first groove strips 33 are provided.

[0048] In this embodiment, the cantilever main beam mounting component 2 used to fix the cantilever main beam 3 specifically adopts a U-shaped component 21. Its bottom needs to pass through the internal steel bars 51 of the N+1 floor slab 5. The cantilever main beam 3 is inserted into multiple U-shaped components 21, and a cover plate 22 is fixed at the open end of the U-shaped component 21 to constrain the cantilever main beam 3. The cover plate 22 has two through holes, which are matched and sleeved with the top ends of the U-shaped component 21, and the cover plate 22 is attached to the cantilever main beam 3. Furthermore, the top ends of the U-shaped component 21 have external threads, and nuts are screwed onto the top ends of the U-shaped component 21 and screwed until they are attached to the cover plate 22 to achieve fixation. To ensure the strength of the cover plate 22, the thickness of the cover plate 22 is not less than 10mm, and it is made of steel plate.

[0049] It should be emphasized that when the embedded part is on the floor slab, the thickness should be the same as the slab thickness. When it is in the beam, the embedded thickness should be no less than 200mm. The thickness of the structural floor slab should not be less than 100mm. The grade of the main concrete should not be less than C20. The reinforcing bars under the U-shaped part 21 should be strengthened. Each U-shaped part 21 should be provided with 3 longitudinal and 2 transverse reinforcing bars with a diameter of 16mm and a length of 1200mm, which should be inserted into the floor slab and welded or tied to the reinforcing bars 51 in the floor slab. When the U-shaped part 21 is set in the beam, 2 longitudinal and 2 transverse reinforcing bars should be provided.

[0050] In one set of cantilever main beam installation components 2, at least three adjacent U-shaped components 21 are provided at one end of the floor slab 6 extending into the cantilever layer N+1. The spacing between the remaining U-shaped components 21 is no more than 1.5m, and the U-shaped components 21 are formed by cold bending.

[0051] After the cantilever main beam 3 and the inclined beam 4 are fixed, and the cantilever main beam 3 is installed on the cantilever main beam mounting component 2 on the N+1 floor slab 5, the inclined beam 4 is inserted into the N floor slab 6. In order to protect the N floor slab 6, the inclined beam 4 is also stably supported, so that it can sustainably support the cantilever main beam 3 and distribute the weight above to the floor. Specifically, the inclined top mounting component 1 includes a flat plate 11, and two hook rods 12 are installed below the flat plate 11. The hook rods 12 are hooked to the steel bars 51 inside the N floor slab to form a pre-embedded part. After the two steel plates 12 above the inclined top mounting component 1 are flipped, they are vertically welded to the flat plate 11. The groove formed in the middle part of the upper part of the flat plate 11 allows the inclined beam 4 to be inserted into it and welded, so that the bottom of the inclined beam 4 is fixed to the inclined top mounting component 1.

[0052] However, the bottom of the inclined beam 4 is designed with an inclined surface to accommodate its tilted installation. After adjusting the distance of the cantilever, the tilt state of the bottom of the inclined beam 4 changes accordingly. To ensure that the inclined beam 4 always maintains the best connection with the groove in the middle of the plate 11, several second grooves 13 are vertically arranged on one side of the groove. The inclined beam 4 abuts and inserts into a second groove 13. When the inclined beam 4 is under force, the constraint of the second groove 13 can effectively prevent the inclined beam 4 from detaching when the inclination is large, thus ensuring that the installation at the bottom of the inclined beam 4 always maintains a stable connection. In this embodiment, six second grooves 13 are provided.

[0053] After the main frame consisting of the cantilever main beam 2 and the inclined beam 4 is erected, before the secondary frame is erected, the Nth floor slab 6 is protected to prevent the inclined beam 4 from bearing too much pressure, which would cause excessive local stress concentration in the Nth floor slab 6. Therefore, a top support frame 9 is set directly below the inclined beam 4.

[0054] The construction of a top support frame at the location directly below the inclined beam on the N-1 floor includes:

[0055] At the bottom of the inclined top mounting component 1, a hook rod 12 partially penetrates the floor slab. The top support frame 9 is vertically arranged with the part through which the hook rod 12 passes as the axis and a radius of 1 to 1.2m.

[0056] Specifically, directly below the inclined roof mounting component 1, the installation position of the inclined beam 4 is located at the bottom of a hook rod 12 that passes through the floor slab. This allows the return frame 9 to be accurately placed against the Nth floor slab 6, distributing the pressure to the N-1th floor slab. Through the joint support of the three floor slabs, the pressure can be maximized. The return frame 9 consists of several vertical rods 93 connected by several horizontal rods 92. When the length of the vertical rods 93 is limited, a top support 91 can be fitted onto the top of at least two vertical rods 93. The top support 91 is a horizontal rod with a top pipe welded on top and a sleeve that fits onto the vertical rods 93 below. The length of the top pipe does not exceed 200mm and it rests against the Nth floor slab 6. In this embodiment, the spacing between adjacent vertical rods 93 and horizontal rods 92 is at least 50cm, which can form a regional support for the Nth floor slab 5, effectively helping to distribute the pressure of the inclined beam 4.

[0057] After the top support frame 9 is installed, the secondary frame is erected. Uprights 71 are vertically welded to both ends of the secondary beam 7, and positioning reinforcement is implemented. Multiple uprights 71 are connected. Ground-level bracing 73 is welded upwards at intervals from a height of 20cm above the surface of the secondary beam 7, with adjacent bracing 73 spaced 50cm apart, forming a guardrail with the uprights 71. Scaffolding (not shown in the diagram) is installed within this guardrail to ensure the stability of the uprights 71 and the safety of the construction. Furthermore, the spacing of the cantilevered main beams 3 should be set according to the longitudinal spacing of the uprights 71 in the cantilever section, with one cantilevered main beam 3 installed for each longitudinal spacing.

[0058] The scaffolding is surrounded by a qualified gray close-mesh safety net 74 certified by the construction authority, and the safety net is fixed to the inside of the outer uprights 71. A 1.5m high guardrail (not shown in the diagram) and a 200mm high kickboard (at least 180mm high) must be installed on the outer side of the top scaffolding. There must be at least two guardrails in the top row, with heights of 0.6m and 1.2m respectively. Due to the large protruding structure of the cantilevered part of the scaffolding, a single-row protective scaffolding is used. The scaffolding can be pre-installed with the roof. Horizontal ground bracing 73 is connected to the completed structural columns. The horizontal and longitudinal ground bracing 73 is installed every two spans, with a minimum of three spans, to ensure the stability of the scaffolding. In this embodiment, 16mm lead wire is used to hang the safety net 74, requiring it to be tight and flat.

[0059] After the secondary frame is erected, the final step is to erect the extra-long casting formwork 8. The steps for erecting the extra-long casting formwork 8 are as follows: The extra-long formwork is laid and tied onto the steel mesh 73 and the ground-level bracing 73 to form the extra-long casting formwork 8, with a casting cavity inside. To further verify the stability of the extra-long casting formwork 8 in its cantilevered state, a monitoring support 81 can be placed on the extra-long casting formwork 8 before casting. The observation points of the extra-long casting formwork 8 are divided into settlement observation points and displacement observation points, mainly set on the extra-long formwork. One observation point is set in each span of the extra-long formwork, with the observation point located at the top step distance. The monitoring support 81 serves as the observation point. Monitoring points can be set up according to the monitoring items, selecting the uprights with the greatest stress, the uprights 71 with weak stability around the support, and the uprights with the greatest stress or low foundation bearing capacity. In this embodiment, the extra-long formwork is a composite board.

[0060] It is important to emphasize that after the scaffolding is erected, monitoring should be conducted once, ensuring its safety and stability, to guarantee its stability under conditions of no construction disturbance and no overnight supervision. Monitoring can be conducted manually once after the scaffolding is erected and the formwork and reinforcing bars are tied, continuing until concrete pouring. During concrete pouring, real-time monitoring should be conducted by a professional third-party monitoring unit, generally not exceeding once per hour. Monitoring can be controlled from before concrete pouring until 12 hours after pouring is completed.

[0061] Monitoring frequency: Monitor once before pouring concrete and record the data at each monitoring point. This data will serve as the baseline for future monitoring. During concrete pouring, monitoring should be prioritized. Generally, during the initial setting period, monitor every 20-30 minutes for 2-3 hours. After initial setting and before final setting, monitor every hour for 4-6 hours. After pouring, monitor again. If no problems are found, no further monitoring is necessary.

[0062] Finally, concrete is vibrated and poured onto the extra-long formwork, including:

[0063] The pouring process was carried out simultaneously using a combination of bucket and tower crane hoisting methods and manual vibration. In extra-long casting formwork, a symmetrical expansion pouring method was adopted from the middle to both ends. Specifically:

[0064] Pouring sequence: First pour the walls and columns, then pour them in layers and sections. The beam concrete is poured using a pouring method that expands symmetrically from the middle of the span to both ends. The slab concrete is poured using a pouring method that expands symmetrically from the middle to both sides.

[0065] Pouring method: Pouring is carried out simultaneously using a combination of bucket and tower crane hoisting and manual vibration.

[0066] 1) During the pouring process, ensure that the concrete is poured symmetrically to avoid generating horizontal dynamic loads on the support frame. A dedicated person should monitor the concrete pouring process, with particular emphasis on monitoring the deformation of the support system.

[0067] 2) Concrete pouring is carried out using a flat plate vibrator (not shown in the diagram) or an immersion vibrator.

[0068] 3) The free fall height of concrete from the bucket opening shall not exceed 2m.

[0069] 4) Concrete pouring should be carried out in accordance with the structural characteristics and the density of the reinforcing bars. For beam concrete pouring, it should be carried out in layers, and the thickness of each layer should not exceed 400mm. During the concrete pouring process, a dedicated person should be assigned to supervise and strengthen the deformation monitoring of the support system. If any loosening or deformation is found, the pouring must be stopped immediately, the workers evacuated, and corresponding reinforcement measures taken.

[0070] 5) When using an immersion vibrator, insert it quickly and withdraw it slowly. The insertion points should be evenly spaced, moved point by point, and performed sequentially without omission to ensure uniform compaction. The moving distance should not exceed 1.5 times the vibratory radius (generally 300-400mm). When vibrating the upper layer, insert the vibrator 50-100mm into the lower layer to eliminate the joint between the two layers. At beam-column joints or when reinforcement is dense, the vibrator moving distance should be approximately 20cm, and a φ30 vibrator should be used simultaneously.

[0071] 6) Concrete pouring must be continuous and uninterrupted. If an interruption is necessary, the interval should be minimized, and the next layer of concrete should be poured one hour before the initial setting of the previous layer.

[0072] 7) When pouring concrete, carpenters and steelworkers should be assigned to be on duty to observe whether the formwork, steel bars, embedded parts and dowel bars have moved, deformed or blocked. If any problems occur, they should be dealt with immediately and corrected before the poured concrete has initially set.

[0073] 8) When hoisting concrete, continuous operation must be ensured. If a malfunction occurs, the downtime exceeds 45 minutes, or the concrete segregates, the remaining concrete in the pipe should be flushed immediately with pressurized water or other methods.

[0074] 9) Special attention should be paid to the pouring of concrete in areas with dense reinforcement during vibration. When the reinforcement is too dense and it is difficult to insert the vibrator, a small diameter 30mm vibrator can be used. In areas with dense hidden beams, it is not easy to vibrate with the vibrator. An additional steel pipe can be inserted and the vibrator can be vibrated inside the steel pipe.

[0075] 10) Beam concrete should be poured and vibrated in layers, and the thickness of each pour should not exceed 400mm. Due to the complex stress situation of the main frame beam, cold joints should not be left during concrete construction.

[0076] 11) Wall and column concrete pouring: For walls and columns exceeding 5m in height, a layered and segmented pouring method should be adopted. First, pour the wall and columns on both sides of the high formwork area, with the first segment poured at one-third of the height. Then pour the adjacent wall and columns. Before the wall and column concrete reaches a certain strength and initial set, pour the second segment of concrete at two-thirds of the height, and so on, until the bottom of the beam is reached. Beam and slab concrete pouring should begin after the third segment of wall and column concrete has been poured but before it has initially set, to avoid construction joints. The first layer of wall and column concrete pouring should not exceed 400mm, and subsequent layers should not exceed 500mm.

[0077] 12) Beam and Slab Concrete Pouring: Beam concrete is poured in one go. Beams and slabs are poured in a frame grid sequence. For each frame grid, the beam is first poured in layers according to its height, forming a stepped shape. When it reaches the bottom of the slab, it is poured together with the slab concrete. As the stepped shape continues to extend, it can be continuously advanced forward. The direction of pouring concrete is opposite to the direction of pouring. The sides and bottom of the beam should be compacted with a φ30 or φ50 immersion vibrator. During vibration, the reinforcing bars and embedded parts should not be touched. When the reinforcing bars at beam and column joints are dense, a small-diameter vibrator should be used, and the vibrator frequency should be increased. The construction of concrete beams should be carried out symmetrically from the middle of the span to both ends. The concrete pouring sequence should be from far to near, vertical first and then horizontal, and low to high.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A construction method for ultra-long cantilever formwork, characterized in that, include: Step 1, Pre-embedding: Pre-embed several sets of inclined roof installation parts in the Nth floor slab, and pre-embed several sets of cantilever main beam installation parts in the N+1th floor slab; Step 2, main frame erection: Install a cantilever main beam on each set of cantilever main beam installation components on the N+1 floor slab, install an inclined beam under the cantilever main beam, and install the inclined top installation components of the N floor slab below the inclined beam to form an ultra-long cantilever main frame; Step 3, Erection of the secondary frame: Several sets of secondary beams are erected parallel above the main frame, uprights are erected above the secondary beams, and ground-level bracing is erected vertically on the multiple uprights to form the secondary frame; Step 4, Formwork Monitoring: Erect extra-long pouring formwork on the auxiliary frame, and vibrate and pour concrete on the extra-long pouring formwork. After the main frame is erected and before the secondary frame is erected, a top support frame needs to be erected on the N-1 floor directly below the inclined beam. The top support frame erection on the N-1 floor directly below the inclined beam includes: a hook rod at the bottom of the inclined top installation part partially penetrates the floor slab, and the top support frame is vertically arranged with a radius of 1~1.2m around the hook rod penetration part as the axis. The inclined beam installation position is located directly below the inclined top installation part through the bottom of the hook rod penetrating the floor slab, so that the top support frame can be accurately abutted against the floor slab of the N floor, and the pressure is distributed to the floor slab of the N-1 floor, forming a joint support of the three floor slabs N+1, N, and N-1 to assist the inclined beam in bearing the pressure, thereby improving the bearing capacity of the cantilever main beam during pouring when erecting ultra-long cantilever formwork. An inclined beam is installed under the cantilever main beam, including: several parallelogram protrusions are set at intervals below the cantilever main beam, and a groove matching the parallelogram protrusions is set above the inclined beam. The groove is closed on three sides, and the side away from the floor slab is open. The inclined beam is obliquely abutted against the underside of the cantilever main beam. The parallel groove above the inclined beam is fitted with the parallelogram protrusions below the cantilever main beam with the inclined direction facing the installation direction of the inclined beam. The inclined beam is fixed to the inner side and the left and right sides by angle steel. The outer side of the inclined beam is fixedly connected to the inclined beam protrusions. As the distance through the cantilever increases, the connection position between the inclined beam and the cantilever main beam needs to be adjusted. The corresponding adjustment of the installation position of the top of the inclined beam and the corresponding parallelogram protrusion must satisfy the following: the fixed length of the cantilever main beam is at least 1.25 times the cantilever length, and the installation position of the top of the inclined beam is located at 3 / 5 of the cantilever main beam in the direction towards the cantilever end.

2. The construction method for an ultra-long cantilever formwork according to claim 1, characterized in that, The aforementioned pre-embedded sets of inclined roof mounting components on the Nth floor slab and pre-embedded sets of cantilever main beam mounting components on the N+1th floor slab include: The cantilever main beam installation component is a U-shaped component, the bottom of which needs to penetrate the internal steel bars of the N+1 floor slab. The cantilever main beam is inserted into multiple U-shaped components, and a cover plate is fixed at the open end of the U-shaped component to restrain the cantilever main beam.

3. The construction method for an ultra-long cantilever formwork according to claim 1, characterized in that, The method of pre-embedding several sets of inclined roof installation components in the Nth floor slab and several sets of cantilever main beam installation components in the N+1th floor slab also includes: Two hook rods are installed below the inclined top mounting component. The hook rods are hooked to the steel bars inside the Nth floor slab, and the inclined beam is inserted into the groove formed by the flipping of two steel plates above the inclined top mounting component.

4. The construction method for an ultra-long cantilever formwork according to claim 3, characterized in that: Several grooves are vertically arranged on one side of the groove, and the inclined beam abuts against one of the grooves.

5. A construction method for ultra-long cantilever formwork according to claim 1, characterized in that, The concrete vibration pouring of the extra-long casting formwork includes: using a combination of bucket and tower crane hoisting and manual vibration, and using a symmetrical expansion pouring method from the middle to both ends in the extra-long casting formwork.

Images