Formwork-free suspension type steel-wood combined formwork construction method

Abstract

The invention provides a construction method of a formwork-free suspension type steel-wood combined formwork, and belongs to the technical field of building construction.The construction method comprises the steps that firstly, after a steel structure beam column is installed, a steel bar support is manufactured and fixed to a steel beam flange in a spot welding mode; then machining a steel support beam and mounting the steel support beam on a steel bar support to ensure a proper extension length; battens are fixed on the steel supporting beams through U-shaped components, and batten arrangement is determined through an optimal spacing configuration algorithm; then a wood formwork is laid, the pre-camber is set, and adhesive tape is attached to gaps to prevent slurry leakage; after acceptance check is completed, steel bar binding and concrete pouring are conducted; after the concrete reaches the formwork removal strength, the formwork supporting system is safely removed by adopting a method of cutting a steel bar support step by step; and finally, the materials are classified, sorted and numbered so that the materials can be recycled for construction of the next layer, and the construction efficiency is comprehensively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of building construction, and more particularly, relates to a construction method for a formworkless suspended steel-wood composite formwork. Background Art

[0002] Steel structure buildings are widely used in high-rise buildings, large public buildings, industrial factories and other fields due to their advantages of light weight, excellent seismic performance and short construction period. In steel structure buildings, the concrete pouring of the floor slab is one of the key processes. The traditional process mainly uses a full hall scaffolding formwork support system, that is, a dense vertical pole and horizontal bar are erected under the floor to form a scaffolding system, and a formwork is laid on it to support the concrete pouring. This method has mature process standards and rich construction experience, and can meet the construction requirements of various forms of concrete floor slabs.

[0003] However, the traditional full hall scaffolding support system has obvious problems of low construction efficiency: First, the erection of the scaffolding requires a large amount of manpower and time, usually accounting for more than 30% of the entire floor construction period; second, the installation, fixation, alignment and other processes of the vertical poles and horizontal bars are cumbersome and require fine operation by experienced workers; third, the scaffolding materials need to be manually transported to the construction location, which is particularly time-consuming in high-rise buildings; in addition, the removal of the scaffolding also consumes a large amount of manpower and working hours, and must wait until the concrete reaches a certain strength before starting, becoming a bottleneck in the construction progress.

[0004] The industry has tried various improvement methods, such as aluminum alloy formwork systems, early form removal systems, etc. However, in steel structure buildings, these methods still need to rely on traditional scaffolding as support and have not fundamentally solved the problem of low construction efficiency. Especially in the construction of large-span steel structure floor slabs, the erection and removal efficiency of the formwork support system directly affects the overall construction period, and an efficient technical solution is urgently needed. That is to say, there is a technical problem of low construction efficiency in the formwork support system for the concrete pouring of steel structure floor slabs in the prior art. Summary of the Invention

[0005] In view of this, the present invention provides a construction method for a formworkless suspended steel-wood composite formwork, which can solve the technical problem of low construction efficiency in the formwork support system for the concrete pouring of steel structure floor slabs in the prior art.

[0006] The present invention is implemented as follows: The present invention provides a construction method for a formworkless suspended steel-wood composite formwork, which includes: fabricating a steel bar support after the installation of steel structure beams and columns is completed; fixing the steel bar support on the flange of the steel beam; processing a steel support beam and welding a U-shaped member on the upper surface; installing the steel support beam on the steel bar support; installing wooden square timbers on the steel support beam; laying wooden formwork on the wooden square timbers; carrying out steel bar binding and concrete pouring; cutting the steel bar support and removing the formwork after the concrete reaches the formwork removal strength; classifying, sorting, numbering and recycling the removed materials; wherein the steel bar support is subjected to force calculation through a force system of equations for the steel bar support, and the force system of equations for the steel bar support includes a shear force equation, a bending moment equation, a local compressive stress equation and a weld strength equation, ensuring that the steel bar support has sufficient bearing capacity and realizing a formwork support system without the need to erect a traditional full hall scaffold.

[0007] Among them, in the step of fabricating the steel bar support, according to the spacing between steel beams and the floor slab span, the actual shear stress is calculated by inputting the load transmitted by the steel support beam, the cross-sectional area of the steel bar support, the load distribution coefficient and the strength of the steel bar material through the shear force equation; the actual bending stress is calculated by inputting the load moment transmitted by the steel support beam, the section modulus of the steel bar support, the height of the steel bar support and the overhanging length of the steel bar support through the bending moment equation; and the specification of the deformed steel bar or round steel used for the steel bar support is determined accordingly.

[0008] Among them, in the step of fixing the steel bar support, according to the construction plan, line marking and positioning are carried out on the flange of the floor structure steel beam, and the steel bar support is fixed on the flange of the steel beam by spot welding. The welding strength is checked through the weld strength equation. The weld strength equation inputs the weld length, weld thickness, welding material strength and load acting force to calculate the stress actually borne by the weld, ensuring that the spot welding connection meets the strength requirements.

[0009] Among them, in the step of processing the steel support beam, the length of the steel support beam is the spacing between the structural steel beams minus 100 mm. The maximum deflection value when bearing a uniform load is calculated through the deflection equation of the steel support beam. The deflection equation of the steel support beam inputs the length of the steel support beam, the magnitude of the uniform load, the elastic modulus of the steel and the moment of inertia of the cross-section to determine the specification of the H-shaped steel or channel steel used for the steel support beam.

[0010] Among them, the floor slab deflection compensation equation inputs the floor slab span, the elastic modulus of concrete, the load magnitude and the time influence coefficient to calculate the pre-camber value during the installation of the wooden formwork. The pre-camber value is used to guide the setting of the upward camber height during the installation of the wooden formwork, so that the concrete floor slab can return to the designed plane position after bearing the load.

[0011] Among them, the shear force equation is used to calculate the shear stress borne by the steel bar support. The load transferred by the steel support beam comes from the self-weight of the concrete and the construction load. The cross-sectional area of the steel bar support comes from the diameter and shape of the steel bar support. The load distribution coefficient comes from the load application method. The strength of the steel bar material comes from the steel bar material specifications.

[0012] Among them, in the step of installing the wooden square, the wooden square is positioned and fixed by the U-shaped members welded on the steel support beam. The optimal spacing configuration algorithm is used to determine the spacing of the wooden square. The optimal spacing configuration algorithm considers four key parameters: formwork thickness, concrete load, flexural strength of the wooden square, and deformation limit. At the lap joint, the wooden square extends not less than 15 mm beyond the edge of the steel support beam.

[0013] Among them, the bending moment equation is used to calculate the bending stress of the steel bar support. The load moment transferred by the steel support beam comes from the product of the load and the cantilever length of the steel bar support. The section modulus of the steel bar support comes from the geometric characteristics of the steel bar support. The height of the steel bar support comes from the design dimensions of the steel bar support. The cantilever length of the steel bar support comes from the placement position of the steel support beam.

[0014] Among them, in the step of formwork removal, first cut one end of the steel bar support, place one end of the steel support beam on the lower flange of the structural steel beam, and then cut the other end of the steel bar support. The cutting is carried out by gas cutting or hydraulic pliers.

[0015] Among them, the weld strength equation is used to check the weld strength between the steel bar support and the steel beam. The weld length comes from the connection method between the steel bar support and the steel beam. The weld thickness comes from the construction process requirements. The strength of the welding material comes from the welding material specifications. The load acting force comes from the self-weight of the concrete and the construction load.

[0016] A construction method for a formwork-free suspended steel-wood composite formwork proposed by the present invention creatively eliminates the need for traditional full hall scaffolding by welding steel bar supports on the steel structure beam and directly suspending the formwork using a support system composed of steel support beams and wooden squares, significantly improving the construction efficiency.

[0017] The construction efficiency advantages of this method are reflected in multiple aspects: First, the cumbersome process of scaffolding erection is eliminated. The processes of installing the steel bar supports and the steel support beams are simple and efficient, and the installation time of the floor formwork support system can be shortened to about 40% of the traditional method. Second, the main components of the formwork support system can be prefabricated in the factory, and only assembly and fixation are required on site, reducing the on-site workload. Third, rapid connection methods such as spot welding and U-shaped member positioning are adopted, reducing the dependence on skilled workers. Most importantly, the formwork support system can be safely and quickly removed only by simply cutting the steel bar supports during the removal process, and the formwork removal efficiency is increased by more than 60%.

[0018] From the perspective of mechanical principles, in the present invention, the load is directly transmitted to the main steel structure through the steel bar supports, forming a clear force transmission path, and cooperating with precise engineering calculation equations to ensure the structural safety. This suspended system utilizes the steel structure itself as the support point, improving the construction efficiency by reducing intermediate links. Therefore, the present invention solves the technical problem of low construction efficiency of the formwork support system for concrete pouring of steel structure floors. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the description of the embodiments of the present invention. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 FIG. is a flow chart of a construction method for a formwork-free suspended steel-wood composite formwork;

[0021] Figure 2 FIG. is a partial structural schematic diagram of a formwork-free suspended steel-wood composite formwork;

[0022] Figure 3 FIG. is a schematic diagram of the structure and installation details of a steel bar support;

[0023] In the drawings, the list of components represented by each reference numeral is as follows:

[0024] 10. Steel bar support; 11. Structural steel beam; 12. Steel support beam; 13. U-shaped member; 14. Wooden square. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention.

[0026] As Figure 1 shown, FIG. is a flow chart of a construction method for a formwork-free suspended steel-wood composite formwork provided by the present invention. This method includes the following steps:

[0027] S01. After the installation of the steel structure beam-column is completed, fabricate the steel bar supports according to the beam spacing and floor span, and perform force verification through the force equations of the steel bar supports. For the shear force equation, input the load transmitted by the steel support beam, the cross-sectional area of the steel bar support, the load distribution coefficient, and the strength of the steel bar material to calculate the actual shear stress; for the bending moment equation, input the load moment transmitted by the steel support beam, the section modulus of the steel bar support, the height of the steel bar support, and the overhanging length of the steel bar support to calculate the actual bending stress; accordingly, determine the specifications of the deformed steel bars or round steel bars used for the steel bar supports to ensure that they have sufficient load-bearing capacity;

[0028] S02. Locate the fabricated steel bar supports on the flange of the floor structure steel beam according to the construction plan. After positioning, fix the steel bar supports on the steel beam flange by spot welding. The welding strength is checked by the weld strength equation, which inputs the weld length, weld thickness, welding material strength, and load acting force to calculate the actual stress borne by the weld and ensure that the spot welding connection meets the strength requirements.

[0029] S03. Process the steel support beam according to the spacing of the structural steel beams. The length of the steel support beam is the spacing of the structural steel beams minus 100 mm. Calculate the maximum deflection value when bearing the uniform load through the steel support beam deflection equation, input the length of the steel support beam, the magnitude of the uniform load, the elastic modulus of the steel, and the moment of inertia of the cross-section to determine the specifications of the H-shaped steel or channel steel used for the steel support beam, and weld U-shaped members on the upper surface.

[0030] S04. Install the steel support beam on the steel bar support by using a mobile lift, ensuring that the length of the steel support beam extending out of the steel bar support is not less than 70 mm. When it cannot be satisfied, weld the steel bar support and the steel support beam firmly, and check the compressive stress on the contact surface between the steel bar support and the steel beam through the local compressive stress equation, input the contact area, transferred load, yield strength of the steel, and contact surface shape factor to ensure that the actual compressive stress on the contact surface does not exceed the allowable value.

[0031] S05. Install the wooden square on the steel support beam. The wooden square is positioned and fixed by the U-shaped members welded on the steel support beam. Use the optimal spacing configuration algorithm to determine the spacing of the wooden squares. The optimal spacing configuration algorithm considers four key parameters: formwork thickness, concrete load, flexural strength of the wooden square, and deformation limit value. The wooden square extends out of the edge of the steel support beam by not less than 15 mm at the lap joint.

[0032] S06. After the installation of the wooden square is completed, conduct an acceptance. After passing the acceptance, lay the wooden formwork on the wooden square. Set the camber when installing the wooden formwork. The camber is calculated by the floor deflection compensation equation. Stick tape paper at the joints between the wooden formworks and at the joints between the wooden formworks and the steel beams to prevent leakage of mortar.

[0033] S07. After the acceptance of the wooden formwork, bind the steel bars according to the design drawings and specifications. After the binding is completed, pour the concrete and leave standard-cured specimens and specimens cured under the same conditions.

[0034] S08. After the concrete reaches the formwork removal strength, first cut one end of the steel bar support, place one end of the steel support beam on the lower flange of the structural steel beam, and then cut the other end of the steel bar support. The cutting is carried out by gas cutting or hydraulic pliers.

[0035] S09. Optionally, after dismantling, the wooden formwork, wooden planks, steel support beams and steel bar support materials should be classified, organized and numbered to facilitate their use in the next layer of construction and improve material utilization. The steel bar support force equation group can be used to recalculate whether the requirements are met for the next use based on actual usage.

[0036] like Figure 2 As shown in 3, the formwork-free suspended steel-wood composite formwork refers to a formwork support system that uses a steel support 10 suspended on a structural steel beam 11, and supports the wooden formwork through a steel support beam 12 and a wooden square 14, without the need to set up a traditional full-floor scaffolding.

[0037] Among them, the steel bar support 10 refers to a component made of threaded steel or round steel for hanging the steel support beam 12, and its size is determined according to the size of the structural steel beam 11 and the steel support beam 12.

[0038] The U-shaped member 13 is made of angle steel and welded to the upper surface of the steel support beam 12 to fix the position of the wooden beam 14, which can increase the stability of the entire support system.

[0039] Among them, demolding strength refers to the strength value at which the wooden formwork can be removed after the concrete reaches a certain strength. For slabs with a span of no more than 2 meters, the concrete strength must reach more than 50% of the design strength.

[0040] Among them, the deflection equation of the steel support beam is used to calculate the maximum deflection value when subjected to a uniformly distributed load. The input includes the length of the steel support beam, the size of the uniformly distributed load, the elastic modulus of the steel material, and the moment of inertia of the section. The output is the maximum deflection value of the midpoint of the steel support beam. The length of the steel support beam is derived from the spacing of the structural steel beams 11 minus 100 mm; the size of the uniformly distributed load is derived from the dead weight of the concrete and the standard value of the construction load; the elastic modulus of the steel material is derived from the steel material specification; the moment of inertia of the section is derived from the cross-sectional characteristics of the steel support beam section; the maximum deflection value is used to verify whether the deformation of the steel support beam under the conditions of bearing the dead weight of the concrete and the construction load meets the requirements of the specification.

[0041] Among them, the force equations of the steel support include shear force equation, bending moment equation, local compressive stress equation and weld strength equation;

[0042] The shear force equation is used to calculate the shear stress borne by the steel support. The input includes the load transmitted by the steel support beam, the cross-sectional area of the steel support, the load distribution coefficient and the strength of the steel material. The output is the actual shear stress of the steel support. The load transmitted by the steel support beam comes from the deadweight of the concrete and the construction load. The cross-sectional area of the steel support comes from the diameter and shape of the steel support. The load distribution coefficient comes from the load action mode. The strength of the steel material comes from the steel material specification. The actual shear stress is used for comparison and verification with the allowable shear stress of the steel material.

[0043] The bending moment equation is used to calculate the bending stress of the steel bar support. The inputs include the load moment transferred by the steel support beam, the section modulus of the steel bar support, the height of the steel bar support, and the cantilever length of the steel bar support. The output is the actual bending stress of the steel bar support. The load moment transferred by the steel support beam is derived from the product of the load and the cantilever length of the steel bar support. The section modulus of the steel bar support is derived from the geometric characteristics of the steel bar support. The height of the steel bar support is derived from the design dimensions of the steel bar support. The cantilever length of the steel bar support is derived from the placement position of the steel support beam. The actual bending stress is used for comparison and checking with the allowable bending stress of the steel bar material.

[0044] The local compressive stress equation is used to calculate the compressive stress at the contact surface between the steel bar support and the steel beam. The inputs include the contact area, the transferred load, the yield strength of the steel, and the contact surface shape factor. The output is the actual compressive stress at the contact surface. The contact area is derived from the actual contact area between the steel bar support and the steel beam. The transferred load is derived from the load borne by the steel support beam. The yield strength of the steel is derived from the steel material specifications. The contact surface shape factor is derived from the geometric characteristics of the contact surface. The actual compressive stress is used for comparison and checking with the allowable compressive stress of the steel.

[0045] The weld strength equation is used to check the weld strength between the steel bar support and the steel beam. The inputs include the weld length, the weld thickness, the strength of the welding material, and the load acting force. The output is the stress actually borne by the weld. The weld length is derived from the connection method between the steel bar support and the steel beam. The weld thickness is derived from the construction process requirements. The strength of the welding material is derived from the welding material specifications. The load acting force is derived from the self-weight of the concrete and the construction load. The stress actually borne by the weld is used for comparison and checking with the allowable stress that the weld can bear.

[0046] Among them, the optimal spacing configuration algorithm refers to a calculation method for determining the optimal spacing of the wooden square based on the bearing capacity and deformation requirements of the wooden square, and optimizes the layout of the wooden square by minimizing the amount of wooden square used and meeting the bearing capacity requirements.

[0047] Among them, the floor deflection compensation equation is used to calculate the pre-camber value during the installation of the wooden formwork. The inputs include the floor span, the elastic modulus of the concrete, the load magnitude, and the time influence coefficient. The output is the pre-camber value during the installation of the wooden formwork. The floor span is derived from the structural design drawings. The elastic modulus of the concrete is derived from the concrete material characteristics. The load magnitude is derived from the self-weight of the concrete and the construction load. The time influence coefficient is derived from the creep characteristics of the concrete. The pre-camber value is used to guide the setting of the upward camber height during the installation of the wooden formwork, so that the concrete floor can return to the designed plane position after bearing the load.

[0048] The specific implementation manners of the above steps are described in detail below. The specific implementation manner of step S01 is to first design the production of the steel bar supports according to the distance between the installed steel structure beams and columns and the span of the floor slab. The production process uses the principle of static force analysis and conducts a comprehensive force check through the force equations of the steel bar supports. This system of equations analyzes the force state of the steel bar supports under actual working conditions, including key mechanical indexes such as shear stress and bending stress. In specific implementation, first calculate the actual shear stress through the shear force equation, which takes the load value transmitted by the steel support beam (usually the self-weight of the concrete plus the construction load, generally 4.5 - 5.5 kN / m 2 )、the actual cross-sectional area of the steel bar support、the load distribution coefficient considering uneven force (usually taken as 1.1 - 1.3) and the strength of the steel bar material (for HRB400 grade steel bars, the shear strength is about 240 MPa) as input parameters. Then apply the bending moment equation to calculate the actual bending stress of the steel bar support, which takes the load moment transmitted by the steel support beam (obtained by multiplying the load by the cantilever length)、the section modulus of the steel bar support (proportional to the cube of the steel bar diameter)、the height of the steel bar support (generally 80 - 120 mm) and the cantilever length (usually not exceeding 1 / 3 of the total length of the steel bar support) as input parameters, and the calculation result must be less than the allowable bending stress of the steel bar material. Based on these calculation results, determine the final selected material specifications of the steel bar support. For floor slabs with a span within 3 m, usually select HRB400 grade deformed steel bars with a diameter of Φ12 - Φ16 or Q235 grade round steel to ensure that it has sufficient bearing capacity and the safety factor is not less than 1.5.

[0049] The specific implementation manner of step S02 is to accurately position the fabricated steel bar supports on the flange of the floor structure steel beam according to the construction plan. The positioning process uses the measurement and layout technology, and uses a steel ruler and a marking tool to mark the installation positions of the steel bar supports on the flange of the steel beam, and the spacing is usually 600 - 800 mm. After positioning, fix the steel bar supports on the flange of the steel beam by spot welding. The spot welding process uses arc welding technology, and the welding current is controlled at 120 - 150 A, and the welding time is 3 - 5 seconds. The welding strength is checked through the weld strength equation, which takes the weld length of the spot welding (usually 1.5 - 2 times the diameter of the steel bar support)、the weld thickness (generally 4 - 6 mm)、the strength of the welding material (for E43 electrode, the strength is about 430 MPa) and the actual load acting force as input parameters to calculate the actual stress borne by the weld. The calculation result must be less than the allowable stress of the weld, and the safety factor is not less than 2.0 to ensure the reliability and stability of the spot welding connection. In actual projects, each steel bar support requires at least two spot welding connections to ensure the firm fixation between the support and the steel beam.

[0050] The specific implementation of step S03 is to fabricate the steel support beam according to the actual spacing between adjacent structural steel beams. The length of the steel support beam is calculated using the clearance control principle, that is, taking the spacing of the structural steel beams minus the reserved space of 100 mm to ensure sufficient operating margin during installation. The specification selection of the steel support beam is determined through the deflection control theory. The maximum deflection value under uniformly distributed load is calculated using the steel support beam deflection equation. This equation is based on the beam deflection theory in mechanics of materials, taking the span length of the steel support beam, the magnitude of the concrete and construction uniformly distributed load (usually 4.5 - 6.0 kN / m 2 )), the elastic modulus of steel (usually 2.06×10 5 MPa), and the moment of inertia of the selected steel section as input parameters to calculate the maximum deflection value. For conventional floors, the maximum deflection is controlled within 1 / 250 of the span. According to the calculation results, for floors with a span of 3 - 5 m, H-shaped steel such as H100×50×5×7 or H125×60×6×8 is usually selected; for floors with a span of 2 - 3 m, 10# or 12# channel steel can be selected. After the steel support beam is fabricated, U-shaped members are welded on its upper surface every 400 - 600 mm. The U-shaped members are made of equal-angle steel, with specifications generally being L40×40×4 or L50×50×5, and the weld height is 4 - 6 mm to ensure a firm and reliable connection between the U-shaped members and the steel support beam.

[0051] The specific implementation of step S04 is to accurately install the steel support beam on the pre-fixed steel bar supports using a mobile hydraulic lift (load capacity not less than 300 kg). The principle of mechanical balance is applied during the installation process to ensure that both ends of the steel support beam are evenly stressed and the length extending beyond the steel bar supports is not less than 70 mm. This length is the minimum safe lap length determined based on the bearing capacity distribution theory. When the minimum extension length requirement cannot be met due to space limitations, welding reinforcement technology is used to firmly connect the steel bar supports and the steel support beam through double-sided welding, with the weld length not less than 75% of the cross-sectional perimeter of the steel bar supports, and the weld thickness being 0.6 - 0.8 times the diameter of the steel bar supports. At the same time, the bearing stress on the contact surface between the steel bar supports and the steel beam is checked through the local bearing stress equation. This equation is based on the contact stress theory in mechanics of materials, taking the contact area (usually the actual contact area between the steel bar supports and the steel beam, about 50% - 70% of the cross-sectional area of the steel bar supports), the transferred load value, the yield strength of steel (for Q235 steel, the yield strength is 235 MPa), and the shape factor reflecting the geometric characteristics of the contact surface (usually taking 1.2 - 1.5) as input parameters to calculate the actual bearing stress on the contact surface. The calculation result must be less than 80% of the allowable bearing stress of the steel to ensure that the contact surface does not undergo excessive deformation or local yielding.

[0052] The specific implementation of step S05 is to arrange wooden square timbers on the installed steel support beams. The wooden square timbers are positioned and fixed through the pre-welded U-shaped components on the steel support beams to ensure the close combination of the wooden square timbers and the steel support beams. The optimal spacing configuration algorithm is used to determine the spacing of the wooden square timbers. This algorithm is based on the structural optimization theory and comprehensively considers four key parameters: the formwork thickness (usually 15 - 18 mm), the load of the concrete surface layer (about 24 kN / m 3 multiplied by the floor slab thickness), the flexural strength of the wooden square timbers (about 8 - 10 MPa for pine), and the deformation limit value (usually controlled within 1 / 300 of the span). Through iterative calculations, the algorithm finds the optimal spacing of the wooden square timbers that can not only meet the requirements of bearing capacity and stiffness but also save materials to the greatest extent. For conventional floor slabs, the spacing of the wooden square timbers is usually 300 - 400 mm. At the lap joint of the wooden square timbers, it should be ensured that the wooden square timbers extend beyond the edge of the steel support beam by no less than 15 mm to ensure sufficient bearing length at the end of the wooden square timbers and prevent local instability. The selected specifications of the wooden square timbers are generally 50×100 mm or 60×80 mm pine or fir, and the moisture content is controlled below 15% to ensure the stable and reliable strength of the materials.

[0053] The specific implementation of step S06 is to lay wooden formwork on the installed wooden square timbers. The wooden formwork uses multi-ply plywood with a thickness of 15 - 18 mm, which has sufficient strength and stiffness. The principle of deformation compensation is applied during the installation process to set the camber. The value of the camber is calculated through the floor slab deflection compensation equation. This equation is based on the structural elastic deformation compensation theory and takes the floor slab span (obtained directly from the structural design drawings), the elastic modulus of concrete (usually 2.6×10 4 ~3.0×10 4 MPa), the self-weight of concrete and the magnitude of the construction load, and the time influence coefficient considering the long-term creep effect of concrete (generally taken as 1.5 - 2.0) as input parameters to calculate the required camber value during the installation of the wooden formwork. For floor slabs with a span of 3 - 5 m, the camber is usually set to 1 / 200 - 1 / 150 of the span. The joints between the wooden formworks and the contact surfaces between the wooden formworks and the steel beams are sealed with adhesive tape with a width of 50 - 60 mm to prevent leakage of concrete during the concrete pouring process. After the formwork installation is completed, a level is used to check the flatness to ensure that the surface flatness error does not exceed 3 mm.

[0054] The specific implementation of step S07 is to carry out the steel bar binding work after the wooden formwork passes the acceptance inspection, in accordance with the design drawings and relevant specification requirements. The steel bar binding adopts the positioning binding method. First, set out and position according to the design drawings, and then bind the main bars and distribution bars in sequence. The binding points use No. 22 galvanized iron wire, and the binding strength ensures that the steel bars do not displace. The steel bar binding density is that each intersection at the beam joints and supports is bound, and at other positions, binding is done at alternate points. After binding, install steel bar cushion blocks to ensure that the cover thickness meets the design requirements. Generally, the cover thickness of the floor slab steel bars is 15 - 20 mm. Then carry out the concrete pouring work. The pouring adopts the layered pouring method, with each layer thickness not exceeding 300 mm. Use an inserted vibrator for vibration, and control the vibration time within 20 - 30 seconds to avoid over-vibration or missed vibration. At the same time of concrete pouring, leave standard curing specimens and specimens cured under the same conditions. The standard curing specimens are cured under standard conditions (temperature 20 ± 2°C, relative humidity above 95%) for evaluating the actual strength of the concrete; the specimens cured under the same conditions are cured in the same environmental conditions as the structural entity for judging the actual strength of the concrete in the structural entity. The size of the specimens is a 100×100×100 mm cube, with each group having no less than 3 specimens.

[0055] The specific implementation of step S08 is to carry out the removal work of the formwork support system after the concrete reaches the form removal strength. The form removal strength is determined based on the early strength development law of the concrete. For a floor slab with a span not greater than 2 m, the concrete strength at form removal needs to reach more than 50% of the design strength; for a floor slab with a span of 2 - 4 m, the concrete strength at form removal needs to reach more than 75% of the design strength. The removal process adopts the principle of gradual unloading. First, cut one end of the steel bar support, place one end of the steel support beam under the lower flange of the structural steel beam to form a simply supported structure, and then cut the other end of the steel bar support to complete the removal of the entire support system. The cutting work adopts gas cutting or hydraulic pliers. When using gas cutting, control the oxygen pressure at 0.4 - 0.5 MPa and the acetylene pressure at 0.05 - 0.07 MPa; when using hydraulic pliers, ensure that its cutting ability is greater than the diameter of the steel bar support. The cutting position is 10 - 15 mm away from the steel beam flange to reduce damage to the steel beam and facilitate later treatment. During the removal process, monitor the deformation of the concrete structure and take timely measures when abnormalities are found.

[0056] Step S09 is an optional step, and its specific implementation method is to classify and organize the removed wooden formwork, wooden beams, steel support beams, and steel bar supports, and manage them by numbering. The sorting work adopts the principle of material recycling, classifies according to the function and size characteristics of the components, and sets up a dedicated storage area for each type of material. The numbering management adopts a hierarchical and zonal coding system, and the coding rules include information such as material type, size specification, and number of uses. The wooden formwork is divided into three categories according to its usage condition: intact, slightly damaged, and severely damaged. The intact and slightly damaged ones can be directly used for the next layer of construction; the wooden beams are sorted by length, and those with similar lengths are grouped together; the steel support beams and steel bar supports are stored according to their models and specifications. For components to be reused, the force equations of the steel bar supports are rechecked, and the material fatigue effect is considered during the checking process. The safety factor is increased by 20% compared with the first use. For components that fail the check, reinforcement treatment or replacement is carried out according to the actual situation. The control index of material utilization rate is: the wooden formwork is reused no less than 8 times, the wooden beams are reused no less than 12 times, and the steel support beams and steel bar supports are reused no less than 20 times. Through this systematic material management method, the material utilization rate is significantly improved, and the project cost is reduced.

[0057] The following details the mathematical models or calculation processes involved in the present invention.

[0058] The shear force equation of the steel bar support is specifically expressed as follows:

[0059]

[0060] In the formula, τ is the actual shear stress of the steel bar support, with the unit of MPa; k d is the load distribution coefficient, dimensionless, with a value range of 1.1 - 1.3; F is the load transferred by the steel support beam, with the unit of kN; A is the cross-sectional area of the steel bar support, with the unit of mm 2 ; [τ] is the allowable shear stress of the steel bar material, with the unit of MPa.

[0061] For the steel bar support with a circular cross-section, its cross-sectional area calculation formula is:

[0062]

[0063] In the formula, d is the diameter of the steel bar support, with the unit of mm.

[0064] The bending moment equation of the steel bar support is specifically expressed as follows:

[0065]

[0066] In the formula, σ bσ is the actual bending stress of the steel bar support, with the unit of MPa; M is the load moment transferred by the steel support beam, with the unit of kN·mm; W is the section modulus of the steel bar support, with the unit of mm 3 ; [σ b is the allowable bending stress of the steel bar material, with the unit of MPa.

[0067] For the steel bar support with a circular cross-section, the calculation formula for its section modulus is:

[0068]

[0069] In the formula, d is the diameter of the steel bar support, with the unit of mm.

[0070] The calculation formula for the load moment is:

[0071] M = F·L c ;

[0072] In the formula, F is the load transferred by the steel support beam, with the unit of kN; L c is the overhanging length of the steel bar support, with the unit of mm.

[0073] In step S02, the weld strength equation is specifically expressed as follows:

[0074]

[0075] In the formula, σ w is the stress actually borne by the weld, with the unit of MPa; F is the load acting force, with the unit of kN; l w is the weld length, with the unit of mm; t w is the weld thickness, with the unit of mm; β w is the weld strength coefficient, dimensionless, generally taking 0.7 - 0.8 for spot welding; [σ w is the allowable stress of the weld, with the unit of MPa.

[0076] In step S03, the steel support beam deflection equation is specifically expressed as follows:

[0077]

[0078] In the formula, δ max is the maximum deflection of the steel support beam, with the unit of mm; q is the magnitude of the uniformly distributed load, with the unit of kN / m; L is the length of the steel support beam, with the unit of mm; E is the elastic modulus of the steel, with the unit of MPa, generally taking 2.06×10 5 MPa; I is the moment of inertia of the cross-section, with the unit of mm 4 ; [δ] is the allowable deflection value, with the unit of mm, generally taking L / 250.

[0079] For H-shaped steel, the calculation formula for its sectional moment of inertia is as follows:

[0080]

[0081] In the formula, b is the flange width, in mm; h is the height of the steel section, in mm; t w is the web thickness, in mm; t f is the flange thickness, in mm.

[0082] In step S04, the local compressive stress equation is specifically expressed as follows:

[0083]

[0084] In the formula, σ c is the actual compressive stress of the contact surface, in MPa; F is the transferred load, in kN; A c is the contact area, in mm 2 ; α is the contact surface shape coefficient, dimensionless, with a value range of 1.2 to 1.5; [σ c is the allowable compressive stress of the steel, in MPa, generally taking 80% of the yield strength.

[0085] In step S05, the optimal spacing configuration algorithm involves the optimization calculation of the spacing of the wooden beams, and the specific formula is expressed as follows:

[0086] S opt = min{S|σ max (S) ≤ [σ], δ max (S) ≤ [δ]};

[0087] In the formula, S opt is the optimal spacing of the wooden beams, in mm; S is the variable of the wooden beam spacing, in mm; σ max (S) is the maximum bending stress of the wooden beam at a spacing of S, in MPa; [σ] is the allowable bending stress of the wood, in MPa; δ max (S) is the maximum deflection of the wooden beam at a spacing of S, in mm; [δ] is the allowable deflection value, in mm.

[0088] The calculation formula for the maximum bending stress of the wooden beam is:

[0089]

[0090] In the formula, M max is the maximum bending moment of the wooden beam, in kN·mm; W m is the section modulus of the wooden beam, in mm 3 ; q m$q$ is the linear load borne by the wooden square, with the unit of kN / m, which is determined by the formwork thickness and the concrete load.

[0091] The formula for the maximum deflection of the wooden square is:

[0092]

[0093] In the formula, $E$ m is the elastic modulus of the wood, with the unit of MPa; $I$ m is the moment of inertia of the cross-section of the wooden square, with the unit of mm 4 .

[0094] For a wooden square with a rectangular cross-section, the formulas for its section modulus and moment of inertia of the cross-section are respectively:

[0095]

[0096] In the formula, $b$ m is the width of the wooden square, with the unit of mm; $h$ m is the height of the wooden square, with the unit of mm.

[0097] In step S06, the floor deflection compensation equation is specifically expressed as follows:

[0098]

[0099] In the formula, $\delta$ p is the pre-camber value during the installation of the wooden formwork, with the unit of mm; $k$ t is the time influence coefficient, dimensionless, with the value range of 1.5 - 2.0; $q$ is the load magnitude, with the unit of kN / m; $L$ s is the floor span, with the unit of mm; $E$ c is the elastic modulus of the concrete, with the unit of MPa, generally taking 2.6×10 4 ~3.0×10 4 MPa; $I$ c is the moment of inertia of the floor cross-section, with the unit of mm 4 .

[0100] The formula for the moment of inertia of the floor cross-section is:

[0101]

[0102] In the formula, $b$ s is the floor width, with the unit of mm; $h$ s is the floor thickness, with the unit of mm.

[0103] The steel bar support shear force equation is based on the shear stress theory in material mechanics and considers the shear stress generated when the steel bar support bears the load transferred by the steel support beam. This equation introduces the load distribution coefficient $k$ d, in order to take into account the uneven load distribution in actual engineering, and improve the safety of calculation. The actual shear stress must be less than the allowable shear stress of the material to ensure that the steel support will not fail due to shear.

[0104] The bending moment equation of the steel support is based on the bending stress theory in material mechanics, which takes into account the bending stress generated by the steel support when it is subjected to a load moment. This equation calculates the bending stress by the ratio of the load moment to the section modulus, reflecting the relationship between the load, the geometric characteristics of the support, and the material strength. The actual bending stress must be less than the allowable bending stress of the material to ensure that the steel support will not fail due to bending.

[0105] The weld strength equation is based on the bearing capacity theory of welded structures and takes into account the stress state of the weld when it is under load. The equation introduces parameters such as weld length, thickness and strength coefficient, and fully considers the impact of welding quality on connection strength. The actual weld stress must be less than the allowable stress to ensure the reliability of the welded connection.

[0106] The deflection equation of the steel support beam is based on the beam deflection theory in material mechanics. It uses a fourth-power relationship to reflect the significant effect of length on deflection, which is consistent with the theoretical results in elastic mechanics. The equation takes into account factors such as load size, beam length, material elastic modulus and section inertia moment, and comprehensively evaluates the deformation performance of the steel support beam. The maximum deflection must be less than the allowable deflection to ensure that the steel support beam has sufficient stiffness.

[0107] The local compressive stress equation is based on the contact mechanics theory and takes into account the compressive stress distribution on the contact surface between the steel support and the steel beam. The equation introduces the contact surface shape coefficient and takes into account the influence of the contact surface geometric characteristics on the compressive stress distribution. The actual compressive stress must be less than the allowable compressive stress to prevent excessive deformation or local yielding of the contact surface.

[0108] The optimal spacing configuration algorithm is based on structural optimization theory. By establishing the relationship between the spacing of timber beams and the bearing capacity and deformation, the optimal spacing that meets the strength and stiffness requirements and can save materials to the maximum extent is found. The algorithm takes into account multiple factors such as formwork thickness, concrete load, timber strength and deformation limit, and realizes the optimal design of timber beam layout.

[0109] The floor deflection compensation equation is based on the theory of structural deformation compensation and takes into account the long-term deformation of the concrete floor under load. The equation introduces the time influence coefficient and takes into account the creep effect of concrete, making the pre-camber setting more reasonable. By setting an appropriate pre-camber, the deflection of the floor after bearing the load can be compensated so that the final shape meets the design requirements.

[0110] The force calculation equation for repeated use of steel support is specifically expressed as follows:

[0111]

[0112] In the formula, τ′ is the actual shear stress when the steel bar support is reused, with the unit of MPa; k d is the load distribution coefficient, dimensionless, and its value range is 1.1 - 1.3; F is the load transferred by the steel support beam, with the unit of kN; A is the cross-sectional area of the steel bar support, with the unit of mm 2 ; [τ] is the allowable shear stress of the steel bar material, with the unit of MPa; 1.2 is the increased value of the safety factor during reuse.

[0113] The bending moment checking equation when the steel bar support is reused is specifically expressed as follows:

[0114]

[0115] In the formula, σ b ′ is the actual bending stress when the steel bar support is reused, with the unit of MPa; M is the load moment transferred by the steel support beam, with the unit of kN·mm; W is the section modulus of the steel bar support, with the unit of mm 3 ; [σ b is the allowable bending stress of the steel bar material, with the unit of MPa; 1.2 is the increased value of the safety factor during reuse.

[0116] The weld strength checking equation when the steel bar support is reused is specifically expressed as follows:

[0117]

[0118] In the formula, σ w ′ is the stress actually borne by the weld during reuse, with the unit of MPa; F is the load acting force, with the unit of kN; l w is the weld length, with the unit of mm; t w is the weld thickness, with the unit of mm; β w is the weld strength coefficient, dimensionless; [σ w is the allowable stress of the weld, with the unit of MPa; 1.2 is the increased value of the safety factor during reuse.

[0119] The local compressive stress checking equation when the steel bar support is reused is specifically expressed as follows:

[0120]

[0121] In the formula, σ c ′ is the actual compressive stress of the contact surface during reuse, with the unit of MPa; F is the transferred load, with the unit of kN; A c is the contact area, with the unit of mm 2 ; α is the contact surface shape coefficient, dimensionless; [σ cσ is the allowable compressive stress of the steel, with the unit of MPa; 1.2 is the increased safety factor value for repeated use.

[0122] These repeated - use checking equations consider the fatigue effect of materials and ensure that the components still have sufficient safety performance after multiple uses by increasing the safety factor. The checking equations maintain the same mechanical analysis structure as the initial use, but reduce the allowable stress by 20%, reflecting the possible strength degradation during multiple uses of the components, thus increasing the conservativeness and safety of the design.

[0123] Specifically, the principle of the present invention is: The core technical principle of the present invention lies in establishing a formwork support system based on a suspension mechanism. By directly using the steel structure beam as the support point, the traditional full - hall scaffolding is eliminated, thereby improving the construction efficiency. Specifically, the steel bar support is used as a key connecting component. One end is welded to the steel beam flange to form a fixed end, and the other end supports the steel support beam to form a cantilever structure. This structural design makes the formwork support system show a suspension - type feature, and transfers the self - weight of the concrete and construction loads to the steel bar support through the wooden formwork, wooden square, and steel support beam in sequence, and finally to the main steel structure.

[0124] To ensure the safety and reliability of this suspension - type system, the present invention designs a complete mechanical calculation system. The force - equilibrium equations of the steel bar support comprehensively consider key parameters such as shear force, bending moment, local compressive stress, and weld strength to ensure that the support has sufficient bearing capacity under working conditions; the deflection equation of the steel support beam verifies whether its deformation meets the specification requirements by calculating the maximum deflection value; the optimal spacing configuration algorithm considers factors such as the thickness of the wooden square and concrete load to optimize the spacing of the wooden square to improve efficiency; the floor deflection compensation equation ensures the flatness of the final floor.

[0125] From the perspective of construction technology, the present invention adopts the design concept of standardization and modularization. Each component can be pre - fabricated, and only installation and fixation are required on - site, greatly simplifying the construction process. Especially in the installation link, the steel bar support is fixed on the steel beam by spot - welding, and the wooden square is positioned by U - shaped components. These rapid connection methods significantly improve the installation efficiency. In the demolition link, an innovative method is designed to first cut one - end steel bar support so that the steel support beam falls on the lower flange of the steel beam, and then cut the other end, avoiding the risk of material falling and greatly improving the demolition efficiency.

[0126] In addition, the material classification and numbering system of the present invention enables the components to be recycled in the next - layer construction, not only improving the material utilization rate, but also reducing the material transportation and preparation time, further enhancing the overall construction efficiency. In short, the present invention solves the problem of low construction efficiency caused by the traditional full - hall scaffolding through the suspension - type support mechanism, precise mechanical calculation, and standardized construction process.

[0127] A specific Embodiment 1 of the present invention is provided below. The specific implementation manners of each step in this Embodiment 1 are described in detail as follows.

[0128] The specific implementation manner of step S01 is to first design the production of the steel bar support according to the distance between the installed steel structure beams and columns and the span of the floor slab. The production process adopts the principle of static force analysis, and a comprehensive force check is carried out through the force equations of the steel bar support. This system of equations analyzes the stress state of the steel bar support under actual working conditions, including key mechanical indexes such as shear stress and bending stress. During specific implementation, first calculate the actual shear stress through the shear force equation:

[0129]

[0130] In the formula, τ is the actual shear stress of the steel bar support, with the unit of MPa; k d is the load distribution coefficient, dimensionless, and its value range is 1.1 - 1.3; F is the load transferred by the steel support beam, with the unit of kN; A is the cross-sectional area of the steel bar support, with the unit of mm 2 ; [τ] is the allowable shear stress of the steel bar material, with the unit of MPa.

[0131] For the steel bar support with a circular cross-section, the calculation formula for its cross-sectional area is:

[0132]

[0133] In the formula, d is the diameter of the steel bar support, with the unit of mm.

[0134] Then apply the bending moment equation to calculate the actual bending stress of the steel bar support:

[0135]

[0136] In the formula, σ b is the actual bending stress of the steel bar support, with the unit of MPa; M is the load moment transferred by the steel support beam, with the unit of kN·mm; W is the section modulus of the steel bar support, with the unit of mm 3 ; [σ b is the allowable bending stress of the steel bar material, with the unit of MPa.

[0137] For the steel bar support with a circular cross-section, the calculation formula for its section modulus is:

[0138]

[0139] In the formula, d is the diameter of the steel bar support, with the unit of mm.

[0140] The calculation formula for the load moment is:

[0141] M = F·L c;

[0142] Wherein, F is the load transferred by the steel support beam, with the unit of kN; L c is the overhanging length of the steel bar support, with the unit of mm.

[0143] Based on these calculation results, determine the material specifications of the finally selected steel bar supports. For floor slabs with a span within 3m, HRB400 deformed steel bars with a diameter of Φ12 - Φ16 or Q235 round steel are usually selected to ensure that they have sufficient bearing capacity and the safety factor is not less than 1.5.

[0144] The specific implementation method of step S02 is to accurately position the fabricated steel bar supports on the flange of the floor structure steel beam according to the construction plan. The positioning process uses the measurement and layout technology. Use a steel ruler and marking tools to mark the installation positions of the steel bar supports on the flange of the steel beam, and the spacing is usually 600 - 800mm. After positioning, fix the steel bar supports on the flange of the steel beam by spot welding. The spot welding process uses arc welding technology, and the welding current is controlled at 120 - 150A, and the welding time is 3 - 5 seconds. The welding strength is checked through the weld strength equation:

[0145]

[0146] Wherein, σ w is the stress actually borne by the weld, with the unit of MPa; F is the load acting force, with the unit of kN; l w is the weld length, with the unit of mm; t w is the weld thickness, with the unit of mm; β w is the weld strength coefficient, dimensionless, and generally takes 0.7 - 0.8 for spot welding; [σ w is the allowable stress of the weld, with the unit of MPa.

[0147] The calculation result must be less than the allowable stress of the weld, and the safety factor is not less than 2.0 to ensure the reliability and stability of the spot welding connection. In actual projects, each steel bar support requires at least two spot welding connections to ensure the firm fixation between the support and the steel beam.

[0148] The specific implementation method of step S03 is to process and manufacture the steel support beam according to the actual spacing between adjacent structural steel beams. The length calculation of the steel support beam adopts the clearance control principle, that is, take the spacing between the structural steel beams minus the reserved space of 100mm to ensure sufficient operating margin during installation. The specification selection of the steel support beam is determined through the deflection control theory, and the maximum deflection value when bearing a uniform load is calculated using the steel support beam deflection equation:

[0149]

[0150] Wherein, δ maxδ is the maximum deflection of the steel support beam, with the unit of mm; q is the magnitude of the uniformly distributed load, with the unit of kN / m; L is the length of the steel support beam, with the unit of mm; E is the elastic modulus of the steel, with the unit of MPa, generally taking 2.06×10 5 MPa; I is the moment of inertia of the cross-section, with the unit of mm 4 ; [δ] is the allowable deflection value, with the unit of mm, generally taking L / 250.

[0151] For the H-shaped steel, the calculation formula for the moment of inertia of its cross-section is:

[0152]

[0153] In the formula, b is the flange width, with the unit of mm; h is the height of the section steel, with the unit of mm; t w is the web thickness, with the unit of mm; t f is the flange thickness, with the unit of mm.

[0154] According to the calculation results, for the floor slabs with a span of 3 - 5m, H-shaped steels of H100×50×5×7 or H125×60×6×8 are usually selected; for the floor slabs with a span of 2 - 3m, channel steels of No. 10 or No. 12 can be selected. After the steel support beam is processed, U-shaped members are welded on its upper surface every 400 - 600mm. The U-shaped members are made of equal-angle steel, and the specifications are generally L40×40×4 or L50×50×5, and the weld height is 4 - 6mm to ensure the firm and reliable connection between the U-shaped members and the steel support beam.

[0155] The specific implementation method of step S04 is to accurately install the steel support beam on the pre-fixed steel bar supports by using a mobile hydraulic lift (with a load capacity of not less than 300kg). During the installation process, the principle of mechanical balance is applied to ensure that both ends of the steel support beam are evenly stressed and the length extending out of the steel bar supports is not less than 70mm. This length is the minimum safe lap length determined based on the bearing capacity distribution theory. When the minimum extension length requirement cannot be met due to space limitations, welding reinforcement technology is adopted to firmly connect the steel bar supports and the steel support beam through double-sided welding, and the weld length is not less than 75% of the cross-sectional perimeter of the steel bar supports, and the weld thickness is 0.6 - 0.8 times the diameter of the steel bar supports. At the same time, the bearing stress on the contact surface between the steel bar supports and the steel beam is checked through the local bearing stress equation:

[0156]

[0157] In the formula, σ c is the actual bearing stress on the contact surface, with the unit of MPa; F is the transferred load, with the unit of kN; A c is the contact area, with the unit of mm 2 ; α is the contact surface shape coefficient, dimensionless, and the value range is 1.2 - 1.5; [σc is the allowable compressive stress of the steel, in MPa, generally taking 80% of the yield strength.

[0158] The calculation result must be less than 80% of the allowable compressive stress of the steel to ensure that excessive deformation or local yielding does not occur on the contact surface.

[0159] The specific implementation of step S05 is to arrange wooden squares on the installed steel support beam. The wooden squares are positioned and fixed through the pre-welded U-shaped members on the steel support beam to ensure tight combination between the wooden squares and the steel support beam. The optimal spacing configuration algorithm is used to determine the spacing of the wooden squares:

[0160] S opt =min{S|σ max (S)≤[σ], δ max (S)≤[δ]};

[0161] In the formula, S opt is the optimal spacing of the wooden square, in mm; S is the variable of the spacing of the wooden square, in mm; σ max (S) is the maximum bending stress of the wooden square at a spacing of S, in MPa; [σ] is the allowable bending stress of the wood, in MPa; δ max (S) is the maximum deflection of the wooden square at a spacing of S, in mm; [δ] is the allowable deflection value, in mm.

[0162] The formula for calculating the maximum bending stress of the wooden square is:

[0163]

[0164] In the formula, M max is the maximum bending moment of the wooden square, in kN·mm; W m is the section modulus of the wooden square, in mm 3 ; q m is the linear load borne by the wooden square, in kN / m, determined by the formwork thickness and the concrete load.

[0165] The formula for calculating the maximum deflection of the wooden square is:

[0166]

[0167] In the formula, E m is the elastic modulus of the wood, in MPa; I m is the moment of inertia of the cross-section of the wooden square, in mm 4 .

[0168] For a wooden square with a rectangular cross-section, the formulas for calculating its section modulus and moment of inertia of the cross-section are respectively:

[0169]

[0170]

[0171] In the formula, b m is the width of the wooden square, with the unit of mm; h m is the height of the wooden square, with the unit of mm.

[0172] For a conventional floor slab, the spacing of the wooden squares is usually 300 - 400 mm. At the lap joint of the wooden squares, it should be ensured that the wooden squares extend beyond the edge of the steel support beam by no less than 15 mm to ensure sufficient bearing length at the end of the wooden squares and prevent local instability. The generally selected specifications of the wooden squares are 50×100 mm or 60×80 mm pine or fir, and the moisture content is controlled below 15% to ensure stable and reliable material strength.

[0173] The specific implementation method of step S06 is to lay a wooden formwork on the installed wooden squares. The wooden formwork uses multi - layer plywood with a thickness of 15 - 18 mm, which has sufficient strength and stiffness. During the installation process, the principle of deformation compensation is applied to set the camber, and the camber value is calculated through the floor slab deflection compensation equation:

[0174]

[0175] In the formula, δ p is the camber value during the installation of the wooden formwork, with the unit of mm; k t is the time - influence coefficient, dimensionless, and its value range is 1.5 - 2.0; q is the load magnitude, with the unit of kN / m; L s is the floor slab span, with the unit of mm; E c is the elastic modulus of concrete, with the unit of MPa, generally taking 2.6×10 4 -3.0×10 4 MPa; I c is the moment of inertia of the floor slab section, with the unit of mm 4 .

[0176] The calculation formula for the moment of inertia of the floor slab section is:

[0177]

[0178] In the formula, b s is the width of the floor slab, with the unit of mm; h s is the thickness of the floor slab, with the unit of mm.

[0179] For a floor slab with a span of 3 - 5m, the camber is usually set to 1 / 200 - 1 / 150 of the span. The joints between the wooden formworks and the contact areas between the wooden formworks and the steel beams are sealed with adhesive tapes with a width of 50 - 60mm to prevent leakage of concrete during pouring. After the formwork installation is completed, a level is used to check the flatness to ensure that the surface flatness error does not exceed 3mm.

[0180] The specific implementation manners of steps S07 - S08 are the same as those described above and will not be elaborated in detail here.

[0181] Step S09 is an optional step. Its specific implementation manner is to classify, sort, and manage the numbered wooden formworks, wooden squares, steel support beams, and steel bar supports removed. The sorting work adopts the principle of material recycling and classifies according to the functional and dimensional characteristics of the components, and storage areas are set for each type of material. The numbered management adopts a hierarchical and zonal coding system, and the coding rules include information such as material type, size specification, and number of uses. The wooden formworks are divided into three categories according to their usage conditions: intact, slightly damaged, and severely damaged. The intact and slightly damaged ones can be directly used for the next - layer construction; the wooden squares are sorted by length, and those with similar lengths are grouped together; the steel support beams and steel bar supports are stored according to their models and specifications. For the components to be reused, the force equations of the steel bar supports are recalculated, and the material fatigue effect is considered during the calculation process, and the safety factor is increased by 20% compared with the first use:

[0182]

[0183] In the formula, τ′ is the actual shear stress when the steel bar support is reused, with the unit of MPa; k d is the load distribution coefficient, dimensionless, with a value range of 1.1 - 1.3; F is the load transferred by the steel support beam, with the unit of kN; A is the cross - sectional area of the steel bar support, with the unit of mm 2 ; [τ] is the allowable shear stress of the steel bar material, with the unit of MPa; 1.2 is the increased value of the safety factor during reuse.

[0184] The bending moment checking equation when the steel bar support is reused:

[0185]

[0186] In the formula, σ b ′ is the actual bending stress when the steel bar support is reused, with the unit of MPa; M is the load moment transferred by the steel support beam, with the unit of kN·mm; W is the section modulus of the steel bar support, with the unit of mm 3 ; [σ b is the allowable bending stress of the steel bar material, with the unit of MPa; 1.2 is the increased value of the safety factor during reuse.

[0187] Weld strength checking equation for repeated use of steel bar supports:

[0188]

[0189] In the formula, σ w ′ is the actual stress borne by the weld during repeated use, with the unit of MPa; F is the load acting force, with the unit of kN; l w is the weld length, with the unit of mm; t w is the weld thickness, with the unit of mm; β w is the weld strength coefficient, dimensionless; [σ w is the allowable stress of the weld, with the unit of MPa; 1.2 is the safety factor increase value during repeated use.

[0190] Local compressive stress checking equation for repeated use of steel bar supports:

[0191]

[0192] In the formula, σ c ′ is the actual compressive stress at the contact surface during repeated use, with the unit of MPa; F is the transferred load, with the unit of kN; A c is the contact area, with the unit of mm 2 ; α is the contact surface shape coefficient, dimensionless; [σ c is the allowable compressive stress of the steel, with the unit of MPa; 1.2 is the safety factor increase value during repeated use.

[0193] For components that fail the checking, reinforcement treatment or replacement shall be carried out according to the actual situation. The control indexes for material utilization rate are as follows: the formwork made of wood shall be reused no less than 8 times, the wooden square shall be reused no less than 12 times, and the steel support beam and steel bar support shall be reused no less than 20 times. Through this systematic material management method, the material utilization rate is significantly improved, and the project cost is reduced.

[0194] It should be noted that the detailed explanations of the variables involved in the present invention are shown in the following table.

[0195] Table 1 Variable Explanation Table

[0196]

[0197]

[0198] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or replacements, which should all be covered within the protection scope of the present invention.

Claims

1. A construction method for a formworkless suspended steel-wood composite formwork, characterized in that, Including: After the installation of steel structure beams and columns is completed, the steel bar supports are fabricated; the steel bar supports are fixed on the flange of the steel beam; the steel support beam is processed and a U-shaped member is welded on the upper surface; the steel support beam is installed on the steel bar support; the wooden square is installed on the steel support beam; the wooden formwork is laid on the wooden square; the steel bars are tied and the concrete is poured; after the concrete reaches the formwork removal strength, the steel bar supports are cut and the formwork is removed; the removed materials are classified, numbered and recycled; among them, the steel bar supports are subjected to force calculation through the steel bar support force equations, and the steel bar support force equations include shear force equation, bending moment equation, local compressive stress equation and weld strength equation to ensure that the steel bar supports have sufficient bearing capacity and realize a formwork support system without setting up traditional full hall scaffolding.

2. The construction method of the formworkless suspension steel-wood composite formwork according to claim 1, characterized in that, In the step of fabricating the steel bar supports, according to the spacing between the steel beams and the floor slab span, the actual shear stress is calculated by inputting the load transferred by the steel support beam, the cross-sectional area of the steel bar support, the load distribution coefficient and the strength of the steel bar material through the shear force equation; the actual bending stress is calculated by inputting the load moment transferred by the steel support beam, the section modulus of the steel bar support, the height of the steel bar support and the overhanging length of the steel bar support through the bending moment equation; and accordingly, the specifications of the deformed steel bars or round steel bars adopted for the steel bar supports are determined.

3. The construction method of the formworkless suspended steel-wood composite formwork according to claim 2, characterized in that, In the step of fixing the steel bar supports, according to the construction plan, the position is marked on the flange of the floor structure steel beam, and the steel bar supports are fixed on the flange of the steel beam by spot welding. The welding strength is checked through the weld strength equation. The weld strength equation inputs the weld length, weld thickness, welding material strength and load acting force to calculate the stress actually borne by the weld and ensure that the spot welding connection meets the strength requirements.

4. A construction method of a formwork-free suspended steel-wood composite formwork according to claim 3, characterized in that In the step of processing the steel support beam, the length of the steel support beam is the spacing between the structural steel beams minus 100 mm, and the maximum deflection value under uniform load is calculated through the steel support beam deflection equation. The steel support beam deflection equation inputs the length of the steel support beam, the magnitude of the uniform load, the elastic modulus of the steel and the moment of inertia of the cross section to determine the specifications of the H-shaped steel or channel steel adopted for the steel support beam.

5. The construction method of the formworkless suspended steel-wood composite formwork according to claim 4, characterized in that The floor slab deflection compensation equation inputs the floor slab span, the elastic modulus of the concrete, the load magnitude and the time influence coefficient to calculate the pre-camber value during the installation of the wooden formwork. The pre-camber value is used to guide the setting of the upward arch height during the installation of the wooden formwork so that the concrete floor slab can return to the designed plane position after bearing the load.

6. The construction method of the formworkless suspended steel-wood composite formwork according to claim 5, characterized in that The shear force equation is used to calculate the shear stress borne by the steel bar support. The load transferred by the steel support beam comes from the self-weight of the concrete and the construction load. The cross-sectional area of the steel bar support comes from the diameter and shape of the steel bar support. The load distribution coefficient comes from the load action mode. The strength of the steel bar material comes from the steel bar material specifications.

7. A construction method for a formwork-free suspended steel-wood composite formwork according to claim 6, characterized in that, In the step of installing the wooden square, the wooden square is positioned and fixed by the U-shaped member welded on the steel support beam. The optimal spacing configuration algorithm is adopted to determine the spacing of the wooden square. The optimal spacing configuration algorithm considers four key parameters: formwork thickness, concrete load, bending strength of the wooden square and deformation limit value. At the lap joint, the wooden square extends out of the edge of the steel support beam by not less than 15 mm.

8. A construction method for a formwork-free suspended steel-wood composite formwork according to claim 7, characterized in that, The bending moment equation is used to calculate the bending stress of the steel bar support. The load moment transmitted by the steel support beam comes from the product of the load and the cantilever length of the steel bar support. The section modulus of the steel bar support comes from the geometric characteristics of the steel bar support. The height of the steel bar support comes from the design dimensions of the steel bar support. The cantilever length of the steel bar support comes from the placement position of the steel support beam.

9. The construction method of the formworkless suspended steel-wood composite formwork according to claim 8, characterized in that In the form removal steps, first cut one end of the steel bar support, place one end of the steel support beam on the lower flange of the structural steel beam, and then cut the other end of the steel bar support. The cutting is carried out by gas cutting or hydraulic pliers.

10. A construction method for a formwork-free suspension type steel-wood composite formwork according to claim 9, characterized in that, The weld strength equation is used to check the weld strength between the steel bar support and the steel beam. The weld length comes from the connection method between the steel bar support and the steel beam. The weld thickness comes from the construction process requirements. The strength of the welding material comes from the welding material specifications. The load acting force comes from the self-weight of the concrete and the construction load.

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