Cast-in-situ steel pipe support u-shaped safety top support and concrete formwork support construction method

Abstract

The application discloses a cast-in-situ steel pipe support U-shaped safety jacking and a concrete formwork support construction method, wherein the cast-in-situ steel pipe support U-shaped safety jacking comprises a multifunctional support and a clamp type adjusting nut, the multifunctional support comprises a lead screw, a U-shaped steel plate support, a reinforcing rib plate and a keel clamp, the top end of the lead screw is fixedly welded with the bottom center of the U-shaped steel plate support, the connecting part of the lead screw and the U-shaped steel plate support is welded with the reinforcing rib plate, the two sides of the U-shaped steel plate support are respectively welded with the keel clamp, and the keel clamp is used for clamping square wood keels; the clamp type adjusting nut comprises an adjusting nut, a clamp fastener and a pin; the adjusting nut adopts a threaded steel pipe with the same outer diameter as the steel pipe stand, the adjusting nut is provided with a pin shaft sleeve, the adjusting nut and the clamp fastener are connected into an integrated whole through the pin, and the adjusting nut and the steel pipe stand are locked through the bolt on the clamp fastener. The safety jacking has the characteristics of limiting keel, locking stand, vertical stability of the lead screw and universality of various keels.

Description

TECHNICAL FIELD

[0001] The present application relates to cast-in-situ concrete structure formwork support installation technical field, in particular to a cast-in-situ steel pipe support U-shaped safety jacking and formwork support construction method. BACKGROUND

[0002] The U-shaped jacking for building is also known as jacking screw, adjusting screw, oil jacking, etc., and is very common in the application of cast-in-situ structure formwork support system. The U-shaped jacking is used in cooperation with the steel pipe support or scaffold, plays a role of adjusting the height of the support, vertically supporting the load and balancing the upper load. In the conventional cast-in-situ structure steel pipe support structure, the U-shaped jacking is installed on the upper part of the support vertical rod, supports the square wood or steel pipe main keel, can accurately adjust the height of the beam and plate bottom formwork, and ensures that each support point can be balanced in stress. The cast-in-situ steel pipe support structure diagram is shown in Figure 1 .

[0003] The conventional U-shaped jacking is composed of three parts of U-shaped jacking, screw and adjusting nut, the U-shaped jacking steel plate has a thickness of ≥4mm, a width of ≥100mm, a length of ≥100mm and a height of ≥60mm; the screw has two specifications of hollow and solid, the screw length is generally 400mm-700mm, and the screw diameter is The adjusting nut has two forms of bowl-shaped nut and butterfly-shaped nut, and the bowl-shaped nut is generally selected for use on site. The conventional U-shaped jacking structure diagram is shown in Figure 2 .

[0004] Although the traditional U-shaped jacking is very common in the application of cast-in-situ structure construction, there are different degrees of structural defects in the actual operation process on site due to the manufacturing process constraints and human factors. According to the article 6.1.9.2 of the Technical Specification for Safety of Building Formwork (JGJ162-2008), the bottom of the steel pipe column should be provided with a cushion and a base, the top should be provided with an adjustable jacking, the gap between the U-shaped jacking and the beam on both sides should be tightly wedged, the screw rod extending out of the top of the steel pipe should not be greater than 200mm, the gap between the screw rod outer diameter and the column steel pipe inner diameter should not be greater than 3mm, and the upper and lower concentricity should be ensured during installation.

[0005] The design structure of the traditional U-shaped jacking is difficult to meet the above specification requirements in actual use, and the specific performance is as follows:

[0006] 1. The purlins on the U-shaped supports can be made of materials such as square timber, steel pipes, and structural steel, with square timber being the most common. According to the traditional design of the top support, 100*100mm square timber should be used. However, the specifications of construction timber on the market are not uniform. Due to material shortages and rising prices, the cutting size has gradually shrunk, and it is generally difficult to reach 100*100mm. Most of them use 50*90mm specifications. Moreover, when placed upright on the U-shaped supports, there is a large gap between the supports and the two sides of the purlins. The standard requirement that "the gap between the supports and the purlins must be wedged tightly" is basically not followed in actual construction. The square timber is prone to sliding on the supports, causing eccentricity.

[0007] 2. When double steel pipes are used instead of 100*100mm square timber as the joists, the traditional top support does not have a fixing measure to restrain the steel pipes and U-shaped supports, and the steel pipes are difficult to fix by wedging. At the same time, the steel pipes are more likely to slide and shift, resulting in eccentricity.

[0008] 3. The theoretical wall thickness of the support steel pipe is 3.5mm, while the wall thickness of the steel pipe actually used in the market is generally less than 2.8mm. Traditional top supports use an outer diameter... The lead screw, after calculation, showed that the gap between the outer diameter of the lead screw and the inner diameter of the steel pipe upright exceeded the upper limit of 3mm required by the specification, which will cause a large deviation in the verticality of the upright, making it difficult to ensure concentricity during installation. Article 5.1.7.2 of the "Technical Specification for Safety of Formwork in Building Construction" (JGJ162-2008) stipulates that "the load of the load-bearing support column should act directly on the axis of the upright, and it is strictly prohibited to bear eccentric loads, and it should be calculated as a single upright under axial compression; the initial curvature of the steel pipe shall not be greater than 1 / 1000, and its wall thickness shall be calculated according to the actual inspection results." This means that the vertical stability of the U-shaped top support should be strictly controlled to transfer the upper construction load to the steel pipe upright; otherwise, the upright is prone to structural instability due to bearing eccentric loads.

[0009] 4. The specifications require that the threaded rod of the U-shaped top support should not extend more than 200mm beyond the top of the steel pipe. When using fastener-type steel pipes as support pillars, the insertion depth of the top support threaded rod into the pillar should not be less than 180mm, both for safety considerations. The exposed cantilever length of the threaded rod is related to various factors such as the building's clear height, the selection of the support system, the fixed length of the pillars, and the specifications of the main and secondary joists. Therefore, before formwork installation, the formwork system design should be carried out, and calculations should be performed based on the most unfavorable combination of loads it bears. Formwork design drawings, support layout drawings, and detailed structural drawings should be prepared. In actual construction, there is often a lack of stress analysis and calculation of the support system, and a lack of comprehensive safety technical briefings. On-site operation and quality acceptance often rely on experience and intuition. Human factors lead to significant uncontrollable factors, and the phenomenon of excessively long threaded rod extensions or even tilting is very common, seriously affecting the overall stability of the support system and creating safety hazards.

[0010] 5. The top support adjusting nut is manufactured using two processes: cast iron and stamped. Cast iron nuts are made of rough material with poor precision, resulting in quality defects. Stamped nuts, commonly used in construction, are limited by traditional stamping processes, with a thickness of only 3.5 mm, leading to poor load-bearing capacity and resistance to deformation. Furthermore, the cup-shaped buckle at the bottom of the nut is in a linear fit with the steel pipe upright, resulting in a small contact area and insufficient constraint on the steel pipe. This leads to poor resistance to slippage and slippage, creating a potential risk of slippage between the nut and the steel pipe, which in turn affects the verticality and stability of the top support and bracket system.

[0011] 6. Scaffolding collapses occur frequently at construction sites, and the causes are related to a variety of factors, including improper selection or operation of the scaffolding support. Therefore, it is imperative to develop a safe support that meets specifications, has a robust and reliable structure, and can be locked to the uprights to fundamentally ensure the safety and quality of cast-in-place scaffolding. Summary of the Invention

[0012] The purpose of this invention is to provide a construction method for a U-shaped safety top support and formwork support for cast-in-place steel pipe supports, so as to solve the problems existing in the prior art. The safety top support of this invention has the characteristics of limiting keel, locking upright, vertical stability of screw, and universality of various keels.

[0013] To achieve the above objectives, the present invention provides the following solution: The present invention provides a U-shaped safety top support for cast-in-place steel pipe supports, including a multi-functional support and a clamp-type adjusting nut. The multi-functional support includes a screw, a U-shaped steel plate support, reinforcing ribs, and keel clamps. The top of the screw is welded and fixed to the center of the bottom of the U-shaped steel plate support, and the reinforcing ribs are symmetrically welded on both sides of the connection between the screw and the U-shaped steel plate support. Keel clamps are welded to both sides of the U-shaped steel plate support, and the keel clamps are used to clamp square timber keels.

[0014] The clamp-type adjusting nut includes an adjusting nut, a clamp fastener, and a pin; the adjusting nut is made of threaded internal steel pipe with the same outer diameter as the steel pipe upright, and the adjusting nut is equipped with a pin bushing, which connects the adjusting nut and the clamp fastener as a whole; the adjusting nut and the steel pipe upright are locked together by bolts on the clamp fastener.

[0015] In one embodiment, the lead screw is a solid lead screw with a diameter of 38mm, and the lead screw is formed by rolling Q235 round steel through a lead screw machine.

[0016] In one embodiment, the U-shaped steel plate support is made of 5mm steel plate, and the two sides of the U-shaped steel plate support are folded upward; the reinforcing rib is made of 5mm thick triangular steel plate.

[0017] In one of the embodiments, the keel clamp is made of 4mm spring steel wire, the wire is in S-shaped curve, and the curvature of the lower part of the keel clamp is bent according to the outer contour of the double-row steel pipe.

[0018] In one of the embodiments, the height of the adjusting nut is 68mm.

[0019] In one of the embodiments, wing-shaped adjusting members are symmetrically welded on the top of the adjusting nut; and a pin sleeve is welded on the bottom of the adjusting nut.

[0020] In one of the embodiments, the clamp fastener is formed by cold pressing process of 5mm thick steel plate, the clamp fastener comprises a fastener one and a fastener two, one end of the fastener one and the fastener two is connected through a pin and a sleeve, and the other end is connected through a bolt penetrating through the bolt pin plates on the two fasteners.

[0021] The application also provides a cast-in-situ concrete formwork support construction method, which comprises the cast-in-situ steel pipe support U-shaped safety jacking support and the following steps:

[0022] (1) line leveling;

[0023] (2) erecting a steel pipe support

[0024] A horizontal rod is arranged on the top end of the vertical rod of the lower part of the U-shaped safety jacking support along the longitudinal and transverse directions, the spacing between the sweeping rod and the top horizontal rod is evenly distributed to meet the horizontal rod step distance requirement determined by the formwork design, and one horizontal rod is arranged at each step distance in the longitudinal and transverse directions, and the horizontal rod joints are distributed in a staggered manner.

[0025] (3) installing the safety jacking support

[0026] The U-shaped safety jacking support is installed on the top of the support vertical rod, the lead screw is inserted into the vertical rod, the insertion depth is not less than 100mm, the bottom of the adjusting nut is butted against the support vertical rod, the clamp fastener is attached to the outer diameter of the vertical rod, and the fastening bolts on the clamp fastener are loosened in advance to adjust the elevation.

[0027] (4) fine adjustment of the elevation

[0028] The elevation control points measured on the wall and column vertical reinforcement are introduced to the support vertical rod, the height of the safety jacking support at the two ends of each row of vertical rods in the longitudinal and transverse directions is adjusted according to the structural design elevation, then the line is drawn, the wing-shaped adjusting member on the top of the adjusting nut is rotated to rise and fall, the elevation of the jacking support is fine adjusted one by one, and the water flow direction of the U-shaped steel plate support is made to correspond to the longitudinal direction of the main keel.

[0029] (5) locking the vertical rod

[0030] After the elevation of the U-shaped safety jacking support is adjusted, the adjusting nut and the steel pipe vertical rod are locked through the bolts on the clamp fastener.

[0031] (6) Beam plate keel and bottom mold paving

[0032] The main keel is laid on the U-shaped steel plate support, the main keel is clamped in the center of the support after the S-shaped curve of the spring wire is elastically relaxed, and the main keel is clamped in the support center; then the square wood secondary keel is paved, and the secondary keel is planed on both sides; the beam plate bottom mold is paved on the secondary keel;

[0033] (7) Beam plate steel bar binding

[0034] The longitudinal main reinforcement of the main beam and the secondary beam is inserted at the same time, the stirrup is placed first, then the longitudinal main reinforcement is inserted, and the vertical reinforcement is bound; the longitudinal main reinforcement of the secondary beam is supported on the longitudinal main reinforcement of the main beam, and the longitudinal reinforcement joints are mechanically connected;

[0035] (8) Quality acceptance

[0036] After the cast-in-place formwork support is installed, the bottom mold elevation is rechecked by using a level, and the size of each part is detected and corrected by using a steel ruler;

[0037] (9) Floor concrete pouring

[0038] (10) Demolding and cleaning

[0039] The support and the formwork are removed after the beam and plate concrete reaches the specified strength, the beam side formwork should be removed first, then the plate bottom formwork is removed, and finally the beam bottom formwork is removed.

[0040] The present application has the following beneficial technical effects compared with the prior art:

[0041] (1) Better compression resistance, bending resistance and folding resistance

[0042] The lead screw of the safety support is formed by full round steel, the U-shaped steel plate support is thickened to 5mm, the connecting part of the lead screw and the support is welded with a reinforcing plate, the strength and bearing capacity of the vertical support part of the support meet the upper bearing load, and the safety accidents caused by lead screw fracture and support bending damage are completely eliminated.

[0043] (2) Better keel stability and universality

[0044] The keel clamp welded on the U-shaped steel plate support has the functions of clamping the keel and centering and limiting, can ensure that the keel is positioned in the center of the support even if there is a large gap between the support and the keel, ensures that the upper load is transmitted along the axis of the vertical rod, and prevents eccentric load of the support caused by keel deviation; the keel clamp is suitable for various keel materials such as square wood, steel pipe and profile steel, and has good universality.

[0045] (3) Stronger deformation resistance

[0046] The adjusting nut and the clamp fastener are formed by steel plate hydraulic process, which cancels the traditional cast steel fastener production process and breaks the thickness limit of the traditional stamping process. The wall thickness is thickened to 5mm, which prevents the hidden danger of deformation and damage caused by insufficient thickness of the steel part during use, meets the stress function under extreme conditions, ensures the safety of the product and greatly increases the turnover frequency. The height of the adjusting nut is increased to 68mm, which increases the contact area between the adjusting nut and the screw rod, makes the thread engagement more stable, and further improves the anti-deformation performance of the adjusting nut.

[0047] (4) Better anti-slip performance

[0048] The safety top support is connected with the steel pipe stand by a clamp, which is similar to the principle of steel pipe butt fastener. The adjusting nut and the steel pipe stand are locked by the clamp, which changes the linear contact of the traditional top support nut and the steel pipe to the surface contact state, ensures that the top support is always perpendicular to the stand, eliminates the hidden danger of steel pipe slipping, and improves the overall mechanical properties and safety performance of the support system.

[0049] (5) Larger vertical adjustment range

[0050] The clamp type reinforced connection structure can break through the specification limit of the exposed cantilever length of the screw rod, the adjustment range of the top support can be increased to within 400mm, the operation of the site support is more flexible and convenient, and the influence of human factors is overcome, preventing structural instability caused by too long exposed screw rod.

[0051] (6) Promote industry development with higher quality

[0052] The safety top support structure is reasonably compact, the size is accurate, the site installation and disassembly are convenient, fast, stable and reliable, the versatility and turnover are good, which promotes the development of formwork support technology to be fine and professional, meets the needs of high-quality development and standardized construction of the building industry, and plays a positive role in promoting the technical progress of cast-in-place structure engineering. BRIEF DESCRIPTION OF DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0054] Figure 1 It is a schematic diagram of the cast-in-place steel pipe support structure;

[0055] Figure 2 It is a schematic diagram of the conventional U-shaped top support structure;

[0056] Figure 3 It is a schematic diagram of the multifunctional support structure;

[0057] Figure 4 Side view of multifunctional support

[0058] Figure 5 Sectional view of adjusting nut

[0059] Figure 6 Three-dimensional schematic view of adjusting nut

[0060] Figure 7 Sectional view of clasp one in hoop clasp

[0061] Figure 8 Sectional view of clasp two in hoop clasp

[0062] Figure 9 Three-dimensional schematic view of clasp one

[0063] Figure 10 Three-dimensional schematic view of clasp two

[0064] Figure 11 Schematic view of hoop type adjusting nut configuration

[0065] Figure 12 Three-dimensional schematic view of hoop type adjusting nut

[0066] Figure 13 Schematic view of safety support assembly

[0067] Figure 14 Three-dimensional schematic view of safety support assembly

[0068] Figure 15 Schematic view of square timber main joist installation

[0069] Figure 16 Schematic view of double steel pipe main joist installation

[0070] Wherein, 1 lead screw; 2 U-shaped steel plate support; 3 reinforcing rib plate; 4 joist clamp; 5 threaded inner wire steel pipe; 6 wing type adjusting piece; 7 pin shaft sleeve; 8 shaft hole; 9 clasp one; 10 clasp two; 11 pin shaft sleeve; 12 shaft hole; 13 bolt pin plate one; 14 bolt; 15 bolt pin plate two; 16 adjusting nut; 17 hoop clasp; 18 pin; 19 support vertical rod; 20 cast-in-place floor slab; 21 cast-in-place slab bottom die; 22 square timber main joist; 23 square timber secondary joist; 24 U-shaped support; 25 support vertical rod; 26 support horizontal rod; 27 scissor brace; 28 wood backing plate; 29 U-shaped support; 30 lead screw; 31 adjusting nut. DETAILED DESCRIPTION

[0071] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0072] The present application aims to provide a cast-in-place steel pipe support U-shaped safety jacking and formwork supporting construction method to solve the problems in the prior art.

[0073] In order to make the above-mentioned purposes, features and advantages of the present application more apparent and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0074] As shown in Figures 3-16 , the present application provides a cast-in-place steel pipe support U-shaped safety jacking combined by a multifunctional support and a hoop type adjusting nut. The multifunctional support includes a screw rod 1, a U-shaped steel plate support 2, a reinforcing rib plate 3 and a keel clamp 4; the hoop type adjusting nut includes an adjusting nut 16, a hoop fastener 17 and a pin 18.

[0075] To achieve the above technical purposes, the technical solutions of the present application are realized by the following technical measures:

[0076] (1) The safety jacking screw rod 1 is a solid screw rod, which is formed by rolling and pressing a Q235 round steel by a screw rod machine. The gap between the outer diameter of the screw rod 1 and the inner diameter of the steel pipe stand is reduced to 2.2mm, which meets the specification requirements while improving the rigidity and bending resistance of the screw rod 1. (2) The U-shaped steel plate support 2 is made of a 5mm steel plate, which is welded and fixed at the center position of the screw rod 1. A reinforcing rib plate 3 is welded at the connecting part of the screw rod 1 and the support. The reinforcing rib plate 3 is made of a 5mm thick triangular steel plate, which further strengthens the vertical bearing capacity of the steel plate support and prevents its bending deformation.

[0077] (3) The U-shaped steel plate support 2 is additionally provided with a keel clamp 4, which is made of a spring steel wire and is welded on both sides of the steel plate support. The keel clamp 4 plays a role of clamping and limiting the square timber keel. The curvature of the lower part of the keel clamp 4 is bent according to the outer contour of the double-row steel pipe. When the main keel is a double steel pipe, the position of the steel pipe can also be limited. The keel clamp 4 is suitable for various keel materials such as square timber, steel pipe and profile steel, and has good versatility.

[0078]

[0079] ​​​​(4) The elevation adjustment component of the safety jack adopts a clamp-type adjusting nut. The adjusting nut 16 is made of threaded internal steel pipe 5 with the same outer diameter as the steel pipe upright. The height of the nut is increased to 68mm, and the thread engagement between it and the lead screw 1 is more secure and stable. The nut is equipped with a pin bushing 7, which allows for... The pin 18 connects the nut and the clamp fastener 17 into one unit. After the top support elevation is adjusted, the adjusting nut 16 and the steel pipe upright can be locked together by the bolts on the clamp, similar to the principle of steel pipe butt fasteners. This ensures that the nut and the steel pipe upright are in a surface-fitting state and are secured by the clamp. This overcomes the shortcomings of the traditional top support's adjusting nut 16 and the steel pipe being in line-fitting mode, eliminates the hidden danger of steel pipe slippage, and thus ensures the verticality and stability of the top support, improving the overall mechanical performance and safety performance of the support system.

[0080] (5) Due to the adoption of the clamp-type connection structure between the safety top support and the steel pipe upright, the length of the top support screw extending out of the top of the steel pipe can exceed the standard limit of 200mm, and the adjustment range of the top support can reach within 400mm. The on-site support erection operation is more flexible and convenient, overcoming the safety hazards caused by the excessively long exposed top support screw of the traditional system.

[0081] The steps for making a U-shaped safety top bracket are as follows:

[0082] The U-shaped safety top support is composed of a multi-functional support and a clamp-type adjusting nut. The specific dimensions and manufacturing methods of each component are as follows:

[0083] (1) Fabrication of multifunctional support

[0084] Multifunctional support The lead screw 1, U-shaped steel plate support 2, reinforcing rib plate 3 and keel clamp 4 are welded together.

[0085] ① Lead screw 1 adopts Solid lead screw, 500mm in length, is formed by rolling Q235 round steel using a lead screw machine.

[0086] ② The U-shaped steel plate support 2 is made of 5mm steel plate with a plane size of 120*120mm. The two sides of the support are folded upward by 25mm. The center of the support is welded perpendicularly to the screw rod 1, and three reinforcing ribs 3 are radially welded at the connection between the screw rod and the support. The reinforcing ribs 3 are made of 5mm thick triangular steel plate. The welding process is double-sided continuous welding to ensure that the weld is full and meets the load-bearing requirements.

[0087] ③ A keel clamp 4 is welded onto the U-shaped steel plate support 2. The keel clamp 4 adopts... Spring steel wire is made, and the steel wire is in S-shaped curve. The middle part is the narrowest, with a width of 60mm. The upper part is 120mm wide, and the height is 120mm. The inner retraction of the lower part is bent according to the outer contour of the double-row steel pipe. The keel clamp 4 is welded on the inner side of the flange of the steel plate support. The welding angle and firmness are accurately controlled, and the welding height is 3mm.

[0088] (2) Making a hoop type adjusting nut

[0089] The hoop type adjusting nut is composed of an adjusting nut 16, a hoop fastener 17 and a pin 18.

[0090] ① The adjusting nut 16 is made of hot-rolled seamless steel pipe. The outer diameter of the steel pipe is 48mm, which is the same as the outer diameter of the vertical rod. The wall thickness is 7.5mm, and the length is 68mm. The inner wall of the steel pipe is sleeved with a threaded inner wire, and the thread type of the inner wire is matched with the thread of the lead screw. Two wing type adjusting parts 6 are welded on the top of the steel pipe. The length of each side is 50mm, which is used as the adjusting part of the rotating lifting nut. A pin shaft sleeve 7 is welded on the bottom of the steel pipe. The pin shaft sleeve 7 is made of steel plate cold pressing. The size is 27*29mm, and the thickness is 10mm. The shaft hole is drilled on the flat surface, and the single side is cut into a circular arc shape, which is flush with the bottom of the threaded inner wire steel pipe 5 and welded.

[0091] ② The hoop fastener 17 is made of 5mm thick steel plate cold pressing process, which is composed of fastener one 9 and fastener two 10. The fastener is provided with pin shaft sleeve 11 and bolt pin plate on both sides. The pin shaft sleeve 11 is in crank shape, with a thickness of 10mm. The shaft hole is punched vertically and corresponds to the shaft hole on the adjusting nut 16. The fastener one 9 and the fastener two 10 are respectively provided with bolt pin plate one 13 and bolt pin plate two 15. The bolt pin plate one 13 is punched by a puncher to form an elongated bolt hole. The bolt pin plate two 15 is punched to form an open bolt hole. One M10 bolt 14 is provided, which is inserted into the elongated bolt hole of the bolt pin plate one 13, and is used as the hoop locking part.

[0092] ③ The adjusting nut 16 and the hoop fastener 17 are combined. The fastener one 9 and the fastener two 10 are attached to the outer diameter of the nut. The pin shaft sleeve 11 on the fastener is staggered and corresponds to the pin shaft sleeve 7 on the adjusting nut 16. The pin 18 is inserted into the shaft hole to connect them into one, the bolt pin plate on the hoop fastener 17 is aligned, and the M10 bolt 14 is inserted to form a hoop type adjusting nut.

[0093] (3) The lead screw 1 is screwed into the threaded inner wire of the adjusting nut 16 to form a U-shaped safety top support.

[0094] The operation steps of the cast-in-place concrete formwork support construction method are as follows:

[0095] ​​​​Make U-shaped safety top support → line copying → set up steel pipe support → install safety top support → fine adjustment of elevation → lock the vertical rod → beam and slab keel and bottom formwork laying → beam and slab reinforcement binding → quality acceptance → concrete pouring → formwork removal and cleaning

[0096] Specifically as follows:

[0097] (1) Line copying

[0098] Remove the debris on the base, and according to the design drawings and control network coordinates, lay out the positioning axis, beam boundary line, column and wall boundary line, control line, door and window hole position line, and full-frame support vertical rod position line, etc. detailed dimensions, and use the ink pot to pop out the ink line. Measure and copy the +500mm horizontal elevation control point on the vertical reinforcement of the wall and column, and mark it with red tape. The upper edge of the tape is the +500mm horizontal elevation, which serves as the basis for controlling the beam and slab bottom formwork and floor elevation.

[0099] (2) Set up steel pipe support

[0100] Lay a footboard not less than 50mm thick on the base, and set up the full-frame cast-in-place support on the floor. The cast-in-place support should be erected on a flat and solid ground, and the base and the bottom footboard should be flat and tightly attached to disperse the load and prevent the support from sinking. The support is made of 48*3mm steel pipes, which should be free of rust, cracks and hard bends. All the rod members used for support must be inspected and qualified before use. First, place the sweeping rod, then erect the vertical rod one by one. The vertical and horizontal spacing of the vertical rod is determined according to the structural load calculation, which is generally 900-1200mm. The lengthening of the vertical rod is strictly prohibited to be lapped, and it must be connected by butt joint fasteners. The joints of the adjacent two vertical rods should not be in synchronization, and the distance of the joints along the vertical direction should not be less than 500mm. The sweeping rod is set in both directions according to the order of vertical down and horizontal up, and is fixed on the vertical rod at a distance of 200mm from the ground by right-angle fasteners, then the horizontal rods in the vertical and horizontal directions are set up and locked by fasteners.

[0101] A horizontal rod is set up at the top end of the vertical rod at the lower part of the U-shaped top support in the vertical and horizontal directions. The spacing between the sweeping rod and the top horizontal rod is evenly distributed to meet the requirements of the horizontal rod step distance determined by the formwork design. A horizontal rod is set up at each step distance in the vertical and horizontal directions. The joints of the horizontal rods are staggered, and the upper and lower sections of the steel pipe vertical rod should not be fixed on the horizontal rod. The steel pipe support should be horizontal and vertical, and the vertical and horizontal directions should be connected. The support setting should be carried out from one end to the other end in sequence, and the vertical and horizontal directions should be carried out at the same time to prevent the support from losing stability. Connection members and scissors braces should be added to ensure the stability of the support body.

[0102] The verticality of the vertical rod and the levelness of the horizontal rod should be strictly controlled. The overall verticality deviation of the support should not be greater than h / 500 (h is the height of the vertical rod), but the maximum deviation should not be more than 20mm.

[0103] (3) Install safety top support

[0104] Install the U-shaped safety top support on the top of the support vertical rod one by one, insert the screw rod 1 into the vertical rod, and the insertion depth should not be less than 100 mm; adjust the bottom of the adjusting nut to butt against the support vertical rod 19, and the clamp fastener 17 is attached to the outer diameter of the vertical rod. The M10 fastening bolts on the clamp fastener 17 are loosened in advance to adjust the elevation.

[0105] (4) Fine adjustment of elevation

[0106] The elevation control points measured on the wall and column vertical reinforcement are guided to the support vertical rod, and the height of the safety top support at both ends of each row of vertical rods in the longitudinal and transverse directions is adjusted according to the structural design elevation. Then, the alignment is set, the wing-shaped adjusting piece 6 on the upper part of the adjusting nut is rotated and lifted, the elevation of the top support is fine-adjusted one by one, and the water-following direction of the U-shaped steel plate support 2 is made to correspond to the longitudinal direction of the main keel.

[0107] For cast-in-place reinforced concrete beams and slabs, when the span is greater than 4 m, the formwork should be arched, and the arching slope should be adjusted on the top support. When there is no specific requirement in the design, the arching height at the midspan is 1 ‰ ~ 3 ‰ of the full span length.

[0108] (5) Locking the vertical rod

[0109] After the elevation of the safety top support is adjusted in place, the adjusting nut 16 and the steel pipe vertical rod are locked by the bolts on the clamp, similar to the principle of steel pipe butt fastening, to ensure that the nut and the vertical rod are in a face-to-face state and are tightened by the clamp. The top support is always fixed vertically with the vertical rod, eliminating the hidden danger of steel pipe slipping.

[0110] The assembly diagram of the safety top support is shown in Figure 13 , and the three-dimensional schematic diagram is shown in Figure 14 .

[0111] (6) Beam and slab keel and bottom formwork laying

[0112] Lay the main keel on the U-shaped steel plate support 2. The main keel can be made of square wood, steel pipe, section steel, etc. The main keel is clamped into the steel plate support from the upper opening of the keel clamp 4, and the S-shaped elastic relaxation of the spring wire clamps the main keel in the center of the support, playing a limiting and fixing role, preventing eccentric load of the support caused by keel deviation.

[0113] The laying schematic diagram of the square wood main keel is shown in Figure 15 , and the laying schematic diagram of the double steel pipe main keel is shown in Figure 16 .

[0114] The "bridge method" is used to process the joint of the main keel. The top support on the upper part of the vertical rod on both sides of the joint position is adjusted to a certain height, a short square wood is used as a crossbeam, and the ends of the main keel joint are supported on the crossbeam and fixed. It is strictly forbidden to have cantilever phenomenon at the joint of the main keel.

[0115] Then lay 50*80mm square wood keel, the second keel both sides of the planer, center spacing 200mm; on the second keel on the beam plate bottom die, bottom die using 15mm thick double face film wood glue template, according to the floor on the beam edge line, using line drop or infrared line projector will beam edge line to the beam bottom, according to this find the beam bottom die position; plate bottom die long side parallel to the second keel arrangement, the original side pressure angle, with inch nail according to 300mm spacing and second keel nail firm, plate bottom die joint must fall on the square wood keel, prevent the template warping caused by uneven board surface; template joint with sponge tape seal tightly, prevent leakage, clean the mouth in the beam end, plate end position, pouring concrete before plugging.

[0116] (7) beam plate steel bar binding

[0117] The main beam and secondary beam longitudinal reinforcement is inserted at the same time, first place the stirrup, then insert the longitudinal main reinforcement, and bind the frame vertical reinforcement; the longitudinal main reinforcement of the secondary beam is supported on the longitudinal main reinforcement of the main beam, the longitudinal reinforcement joints are all mechanically connected, the upper longitudinal reinforcement joint is set in the 1 / 3 range of the span, the lower longitudinal reinforcement joint is set at the support, the joints in the same connection section are not more than 50%, and the staggered distance is not less than 35d.

[0118] Mark the grade marks of the cast-in-place slab steel reinforcement according to the design spacing, distribute the lower layer reinforcement, mark the grade marks on the lower layer reinforcement, and then distribute the upper layer reinforcement, bind all the lead wires at the longitudinal and transverse intersections, set the protection layer cushion block for the bottom plate steel reinforcement, and perform the water and electricity pre-embedded pipeline construction during the steel bar binding period.

[0119] (8) quality acceptance

[0120] After the installation of the cast-in-place formwork support is completed, the bottom die elevation is rechecked with the level, the sizes of all parts are detected and corrected with the steel ruler, whether the formwork system is firm is checked, and the support jacks should be tightened one by one to make all the vertical rods bear force uniformly.

[0121] (9) floor concrete pouring

[0122] The floor beam and the floor slab are cast simultaneously, the casting method is started from one end by using "sweeping method", i.e. the beam is cast first, the beam is cast in layers according to the height of the beam to form a ladder shape, when the position of the bottom of the floor slab is reached, the concrete of the beam and the floor slab is cast together, with the continuous extension of the ladder shape, the beam and the floor slab are continuously cast forward; the insert vibrator is used to vibrate along the casting direction, the vibration points should be arranged uniformly, the interval is controlled to be about 400 mm, the concrete should not be spread by using the vibrating rod; a person is arranged to check the stability of the formwork and the support system during the concrete casting to prevent accidents; the floor concrete is finished in two times: the surface is scraped to be flat in the first time, then the surface is rubbed by using the wooden trowel, in the second time, the surface is rubbed by using the wooden trowel when the foot has no footprints before the initial setting of the concrete, so that the shrinkage cracks caused by the evaporation of the surface water are prevented; after the beam and the floor slab are cast, the person is prohibited to go up too early, the concrete is covered and watered within 12 hours after casting to keep the wet state, and the curing period is not less than 7 days.

[0123] (10) Demolding and cleaning

[0124] The support and the formwork are removed after the beam and the floor slab concrete reach the specified strength, the beam formwork should be removed first, then the bottom formwork of the floor slab is removed, and finally the bottom formwork of the beam is removed, and the removal should be carried out in sections and pieces, and it is strictly prohibited to pry or pull down in pieces; when the formwork is removed at a high place, the relevant regulations of high-altitude operation should be followed, the hammer and the crowbar should not be used, the temporarily removed formwork on the operation layer should not be stacked more than 3 layers, the operator should stand in a safe place to operate, and it is strictly prohibited to stand on the removed or loosened formwork to carry out the removal operation; the formwork is cleaned in time after the removal, the release agent is painted, and the formwork is stored for standby according to the specifications; the removed safety jacks, fasteners and other components are collected and arranged, the mortar is cleaned, and the components are stored in a dry place for continued circulation.

[0125] It should be noted that for those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application, and any reference signs in the claims should not be regarded as limiting the claims.

[0126] The principles and implementation modes of the present application are described by using specific examples in the present application, the above embodiment description is only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation modes and application ranges will be changed. In conclusion, the content of the present description should not be understood as a limitation of the present application.

Claims

1. A construction method for cast-in-place concrete formwork support, comprising a U-shaped safety top support for cast-in-place steel pipe support, the U-shaped safety top support comprising a multi-functional support and a clamp-type adjusting nut, the multi-functional support comprising a screw rod, a U-shaped steel plate support, reinforcing ribs, and keel clamps, the top of the screw rod being welded and fixed to the center of the bottom of the U-shaped steel plate support, and the reinforcing ribs being symmetrically welded on both sides of the connection between the screw rod and the U-shaped steel plate support, and keel clamps being welded on both sides of the U-shaped steel plate support, the keel clamps being used to clamp square timber keels; the clamp-type adjusting nut comprising an adjusting nut, a clamp fastener, and a pin; the adjusting nut being made of a threaded internal steel pipe with the same outer diameter as the steel pipe upright, the adjusting nut having a pin bushing, the adjusting nut being connected to the clamp fastener as a whole by the pin; the adjusting nut being locked to the steel pipe upright by bolts on the clamp fastener; characterized in that: It also includes the following steps: (1) Level the surface using a chalk line; (2) Erecting steel pipe supports A horizontal bar is set at the top of the vertical pole at the bottom of the U-shaped safety support along both the longitudinal and transverse directions. The distance between the sweeping bar and the top horizontal bar is determined by evenly distributing the step distance while meeting the horizontal bar step distance requirements determined by the template design. A horizontal bar is set in both the longitudinal and transverse directions at each step distance, and the joints of the horizontal bars are staggered. (3) Install safety support Install the U-shaped safety top supports one by one on the top of the support poles, insert the lead screw into the poles to a depth of not less than 100mm; align the bottom of the adjusting nut with the support poles, and fit the clamp fasteners against the outer diameter of the poles. Loosen the fastening bolts on the clamp fasteners beforehand to adjust the elevation. (4) Fine-tuning the elevation The elevation control points measured on the vertical steel bars of the wall and column are transferred to the support poles. The safety support height at both ends of each row of poles in the longitudinal and transverse directions is adjusted according to the structural design elevation. Then, a guide line is laid, and the support elevation is finely adjusted one by one by rotating and raising the wing-shaped adjustment piece on the upper part of the adjusting nut. The direction of the U-shaped steel plate support is aligned with the longitudinal direction of the main keel. (5) After the elevation of the U-shaped safety top support of the locking pole is adjusted to the correct position, tighten the adjusting nut to the steel pipe pole with the bolts on the clamp fastener; (6) Beam and slab joists and bottom formwork installation Lay the main keel on the U-shaped steel plate support, and insert the main keel into the U-shaped steel plate support from the top of the keel clamp. The keel clamp holds the main keel in the center of the support. Then lay the square timber secondary keel and plan both sides of the secondary keel flat. Lay the beam and slab bottom formwork on the secondary keel. (7) Beam and slab reinforcement binding The longitudinal reinforcement of the main and secondary beams are interlaced and laid out simultaneously. First, the stirrups are placed, then the longitudinal main reinforcement is threaded through, and the stirrups are tied. The longitudinal main reinforcement of the secondary beam is supported on the longitudinal main reinforcement of the main beam, and all longitudinal reinforcement joints are mechanically connected. (8) Quality Acceptance After the cast-in-place formwork support is installed, the elevation of the bottom formwork is checked again with a level and the dimensions of each part are checked and corrected with a steel ruler. (9) Floor concrete pouring; (10) Demolding and cleaning After the concrete of beams and slabs reaches the specified strength, the supports and formwork shall be removed. For beam and slab formwork, the side formwork of the beam shall be removed first, followed by the bottom formwork of the slab, and finally the bottom formwork of the beam.

2. The construction method for cast-in-place concrete formwork support according to claim 1, characterized in that: The lead screw is a solid lead screw with a diameter of 38mm, and the lead screw is formed by rolling Q235 round steel through a lead screw machine.

3. The construction method for cast-in-place concrete formwork support according to claim 1, characterized in that: The U-shaped steel plate support is made of 5mm steel plate, and the two sides of the U-shaped steel plate support are folded upward; the reinforcing rib is made of 5mm thick triangular steel plate.

4. The construction method for cast-in-place concrete formwork support according to claim 1, characterized in that: The keel clamp is made of 4mm spring steel wire with an S-shaped curve. The lower part of the keel clamp is curved according to the outer contour of the double-row steel pipe.

5. The construction method for cast-in-place concrete formwork support according to claim 1, characterized in that: The height of the adjusting nut is 68mm.

6. The construction method for cast-in-place concrete formwork support according to claim 1, characterized in that: The top two sides of the adjusting nut are symmetrically welded with wing-shaped adjusting parts; the bottom of the adjusting nut is welded with a pin bushing.

7. The construction method for cast-in-place concrete formwork support according to claim 1, characterized in that: The clamp fastener is formed by cold pressing of 5mm thick steel plate. The clamp fastener includes fastener one and fastener two. One end of fastener one and fastener two are connected by a pin and a bushing, and the other end is connected by a bolt passing through the bolt pin plate on the two fasteners.

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