Construction method for replacing wood with steel and supporting formwork vertical rod

Abstract

The invention provides a construction method for replacing wood with steel and a formwork support vertical rod. A proper main ridge material is selected according to the thickness and load requirements of a floor slab; according to the thickness of a floor slab and the material performance of a main ridge, the distance between formwork vertical rods is determined, and the economical and reasonable distance between the vertical rods is calculated and determined; calculating formwork material requirements under the conditions of specific floor area and story height by utilizing a formwork theoretical quantity calculation principle; actual application adjustment: considering field construction conditions and actual problems, and adjusting a theoretical calculation value to ensure construction feasibility and safety; when a basement formwork is erected, a proper distance between vertical rods is selected, and adjustment is conducted according to the thickness and the size of a plate; for an overground standard layer, a formwork arrangement diagram is drawn, and formwork erecting is conducted according to different requirements of prefabricated slabs and cast-in-place slabs; and the formwork cost of different main ridge materials and vertical rod spacing schemes is compared, and the scheme with the highest cost benefit is selected. The construction efficiency can be improved, the cost is reduced, and the construction safety is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, in particular to a method for replacing wood with steel and a formwork frame pole construction method. Background Art

[0002] With the rapid development of the construction industry, the requirements for construction speed and cost-effectiveness are getting higher and higher. As a key temporary structure in construction, the design and implementation of formwork support frames directly affect the progress and cost of the project. Existing formwork support frame systems usually have problems such as material waste, low construction efficiency, and insufficient safety. Summary of the invention

[0003] In view of the above-mentioned defects of the prior art, the technical purpose of the present invention is to solve the problems of high cost, low construction efficiency, insufficient safety and the like existing in the prior art formwork support frame system in actual construction.

[0004] In order to achieve the above technical purpose, the present invention provides a steel-for-wood and formwork support pole construction method, which includes the following steps: main rib selection planning, formwork pole spacing determination, formwork theoretical quantity calculation, actual construction application and cost comparison; main rib selection planning: select appropriate main rib material according to the thickness and load requirements of the floor slab;

[0005] Determine the spacing between formwork poles: Calculate and determine the economically reasonable spacing between poles based on the thickness of the floor and the performance of the main rib material; Formwork theoretical quantity calculation: Calculate the formwork material requirements under specific floor area and floor height conditions using the principle of formwork theoretical quantity calculation;

[0006] Practical application adjustment: Considering the on-site construction conditions and actual challenges, the theoretical calculation values ​​are adjusted to ensure construction feasibility and safety;

[0007] Basement formwork erection: When erecting the basement formwork, select the appropriate spacing between the vertical poles and adjust it according to the thickness and size of the slab;

[0008] Formwork erection for standard floors above ground: For standard floors above ground, draw a formwork layout diagram and erect formwork according to the different requirements of precast panels and cast-in-place panels;

[0009] Cost comparison: Compare the formwork costs of different main rib materials and vertical pole spacing solutions, and select the most cost-effective solution. Specifically, it includes the following steps:

[0010] (i) Determine the load: Calculate the uniformly distributed load on the floor slab, including dead load and live load;

[0011] q = uniformly distributed load on the floor

[0012] Determine the allowable stress: Determine the allowable stress value based on the characteristics of the pole material;

[0013] Determine the bearing capacity of the pole

[0014] A is the cross-sectional area of ​​the pole, f is the yield strength of the material, and g is the safety factor, with a value of 1.5 to 2.5;

[0015] (ii) Calculate the bearing capacity of the pole: Calculate the bearing capacity of the pole based on its geometric dimensions and material properties;

[0016] Calculate the maximum allowable spacing: Use the mechanical model to calculate the maximum allowable spacing of the poles while meeting safety requirements L is the maximum allowable spacing of the poles while meeting the bearing capacity requirements

[0017] (iii) Consider stability factors: The stability of the pole is affected by compression buckling, lateral support conditions and slenderness ratio factors; K is the effective length coefficient of the pole; E is the elastic modulus of the material, I is the moment of inertia of the pole section, Kcr is the critical load factor, f y is the yield strength of the material;

[0018] (IV) Considering the construction specifications, there are specific requirements for the spacing between the poles as follows:

[0019] L z =min(L,L w ,L g ), L z is the final spacing, Lw is the stability, and Lg is the specification requirement.

[0020] Preferably, the main flute material is preferably a square steel tube or a fastener-type steel tube.

[0021] Preferably, the vertical pole spacing of 1200 / 1200mm is used as the main spacing for erecting the basement formwork.

[0022] Beneficial effects of the present invention:

[0023] Cost-effectiveness: By optimizing the main beam material and the distance between the poles, the material usage and rental costs are reduced.

[0024] Construction efficiency: Simplify the construction process and reduce the time and difficulty of erection.

[0025] Safety: Ensure the reliability and safety of the mold base design.

[0026] Adaptability: Suitable for different construction projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a diagram of the arrangement of small-pitch vertical poles provided in this embodiment.

[0028] Figure 2This is a diagram of the large-spacing pole arrangement provided for this embodiment. DETAILED DESCRIPTION

[0029] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention.

[0030] Example:

[0031] Main flute selection planning

[0032] The main rib is the main load-bearing component of the formwork support frame, and its selection has an important impact on the stability and economy of the entire formwork.

[0033] Material selection: usually you can choose fastener-type steel pipes, square steel pipes, etc.

[0034] Calculation and analysis: According to the load of the floor slab and the mechanical properties of the main rib material, the safe spacing and number of the main ribs can be determined through mechanical calculation software or manual calculation.

[0035] Cost considerations: Compare the unit price, rental cost, purchase cost, and expected life cycle of different materials.

[0036] Determine the spacing between formwork uprights

[0037] The determination of the spacing between poles needs to take into account safety, economy and construction convenience.

[0038] Regulatory basis: Follow relevant construction regulations, such as the "Safety Technical Specifications for Clamped Steel Pipe Scaffolding in Construction".

[0039] Calculation and analysis: Perform structural calculations to ensure that the distance between poles is increased as much as possible while meeting strength and stability requirements, so as to reduce the number of poles.

[0040] On-site adjustment: Make appropriate adjustments to the theoretical calculated values ​​based on on-site conditions and construction experience.

[0041] Theoretical calculation of mold base

[0042] Theoretical quantity calculation is to estimate the total demand for formwork materials.

[0043] Parameter input: including vertical pole spacing, main rib spacing, floor size, floor height, etc.

[0044] Calculation of component quantity: Calculate the quantity of components such as vertical poles, main ribs, secondary ribs, horizontal poles, etc. based on the input parameters.

[0045] Material weight calculation: Calculate the total weight based on the number of components and material density.

[0046] Cost Estimate: Estimate the total cost based on material weight and market price.

[0047] Actual construction application

[0048] Applying theoretical design to actual construction requires consideration of site conditions and operability.

[0049] Construction plan: Develop a detailed formwork erection plan, including construction steps, personnel arrangements, material transportation, etc.

[0050] On-site implementation: Erection is carried out according to the construction plan to ensure that each step of the operation complies with safety regulations.

[0051] Quality inspection: After erection, a comprehensive inspection is carried out to ensure the stability and safety of the formwork.

[0052] Cost comparison

[0053] Cost comparison is to select the most economical construction plan.

[0054] Scheme comparison: List all feasible formwork design schemes.

[0055] Cost calculation: Carry out detailed cost calculation for each plan, including material cost, labor cost, machinery usage fee, etc.

[0056] Economic analysis: Compare the total cost and cost-effectiveness of different solutions, and select the solution with the lowest cost and meeting safety requirements.

[0057] Specific implementation steps

[0058] Information collection: Collect project-related design drawings, construction specifications, material prices and other information.

[0059] Parameter determination: Determine the load of the floor slab and the mechanical properties parameters of the main rib material.

[0060] Mechanical calculation: Use mechanical principles and calculation software to determine the optimal spacing between the main ribs and the vertical poles.

[0061] Calculation of material requirements: Calculate the amount of material required based on the spacing between the vertical poles and the main ribs.

[0062] Cost estimation: Estimate the construction cost based on the material quantity and market price.

[0063] Scheme evaluation: Evaluate the technical feasibility and economic feasibility of different schemes.

[0064] Construction drawing design: Draw the construction drawing of formwork erection, including the arrangement of vertical poles, main ribs, etc.

[0065] On-site implementation: On-site erection according to the construction drawings and construction plans.

[0066] Safety inspection: After erection is completed, a safety inspection is carried out to ensure that safety standards are met.

[0067] Cost accounting: Cost accounting is carried out after the construction is completed and compared and analyzed with the estimated cost.

[0068] Through the above steps, the design and construction of the formwork support system can be ensured to be both safe and economical.

[0069] Specific project overview

[0070] The total land area of ​​this project is 47,693 square meters. The total construction area of ​​the project is 125,945.71 square meters (excluding the overhead floor area (not included in the volume) of 3,202.05 square meters), of which the above-ground construction area is 85,847.4 square meters and the underground construction area is 40,098.31 square meters. The above-ground part mainly consists of 16 single buildings and podiums, including 11 14-story buildings, 2 13-story buildings, 1 12-story building and 2 11-story buildings, with a height of no more than 49.90 meters; the underground part is two stories.

[0071] Buildings 1-16# are cast-in-place reinforced concrete shear wall structures, buildings G1 and G2 are steel structures, and buildings S1-4# and the underground garage are cast-in-place reinforced concrete frame structures.

[0072] Floor distribution overview

[0073] Based on the structural model provided by the company, a floor slab list is generated to analyze the distribution of floor slab thickness in the project.

[0074] In the basement area, slabs with a thickness of 250mm and below account for 67.90%, slabs with a thickness of 300mm account for 31.94%, and slabs with a thickness of more than 300mm account for only 0.15%.

[0075] For example, on the ground, cast-in-place slabs account for 20.77%, and cast-in-place slabs with a thickness of 120 mm or less account for 87.25%; prefabricated slabs account for 79.23%, and prefabricated slabs with a thickness of 130 mm or less account for 94.42%. According to analysis, cast-in-place slabs with a thickness of more than 120 mm and prefabricated slabs with a thickness of more than 130 mm are distributed in the overhead layer and roof layer.

[0076]

[0077]

[0078] Overview of main flute selection

[0079] The formwork materials are divided into four types: formwork frame, main ribs, secondary ribs, and templates. The frame uses Hangzhou Qiangtui disc buckle frame, and the secondary ribs use square wood (40*90mm) to facilitate turnover between projects. The template uses conventional 13-15mm wooden templates.

[0080] At the same time, it has been calculated that the selection of main rib materials and the spacing between secondary ribs are the key variables for adjusting the spacing between the buckle frames, which in turn affects the material cost of formwork erection.

[0081] The project intends to use fastener-type steel pipes (A48mm) and square steel pipes (50*100mm) as the main ribs for planning and analysis.

[0082] After calculation, the main material parameters and unit prices of the mold frame are shown below:

[0083] Material Type Weight / Volume unit price Button 0.00555t / m 3.5 / t / day Wood 0.0036m3 / m 1012 yuan / m3 (cost of use) Square steel pipe 0.00685t / m 35 yuan / t / day Steel pipe 0.0033t / m 3 yuan / t / day

[0084] Note: Timber purchase price: 2012 yuan / m 3 , allocated about 1000 yuan / m 3 The selection of fluting does not affect the template laying area and is not considered for the time being.

[0085] Formwork pole spacing

[0086] Based on the distribution of the project floor slabs, 120mm, 250mm, 300mm thick cast-in-place slabs and 130mm thick prefabricated floor slabs were used for main rib selection planning and analysis. The more economical formwork spacing under different main rib materials was obtained through calculation, as shown in the following table:

[0087]

[0088] 2.3 Theoretical calculation principle of rectangular plate lower formwork

[0089] Take the 20*20m board range and 3.5m floor height as an example for calculation and comparison:

[0090] Under ideal conditions, the vertical pole is 3.5m long and there are 3 rows of horizontal poles. The number of components with a length of 20m at different spacings is shown below:

[0091]

[0092] Take the vertical pole spacing of 0.9*1.2m, the main rib spacing (fastener steel pipe-2 pieces) of 1.2m, and the secondary rib spacing of 0.25m as an example, and calculate according to the above table:

[0093] Number of poles = 23*17 = 391;

[0094] Length = 391*3.5 = 1368.5m;

[0095] Weight = 1368.5*0.00555 = 7.60 tons;

[0096] Number of horizontal bars = 23 + 17 = 40;

[0097] Length = 40*20*3 = 2400m;

[0098] Weight = 3200 * 0.00555 = 13.32 tons;

[0099] Number of main ribs = 17;

[0100] Length = 17*20*2 = 680m;

[0101] Weight = 680*0.0033 = 2.24 tons;

[0102] Number of secondary ridges = 81;

[0103] Length = 81*20 = 1620m;

[0104] Volume = 1620*0.0036 = 5.83m3.

[0105] The cost is: (7.6+13.32)*3.5+2.24*3=79.94 yuan / day, the purchase amount of wood is (5.83*1012)=5902 yuan

[0106] Calculation table

[0107] According to the theoretical calculation principle, the calculation table is made as follows:

[0108]

[0109] The yellow filled items are input items. The number of poles can be taken according to the actual value. The final calculation will be based on the larger value of the actual value.

[0110] According to the actual input corresponding data, the daily cost and wood usage cost are automatically output, and the required data is selected according to the main rib material.

[0111] Theoretical comparison of mold base cost

[0112] According to the calculation table, the cost is as follows:

[0113]

[0114] in conclusion:

[0115] 1. The main fluting material is square steel pipe, which saves 30%-50% of the daily rental cost compared with the fastener steel pipe. At the same time, the cost of the secondary fluting material will increase accordingly.

[0116] 2. The selection and planning of the main ribs should comprehensively consider the formwork rental period and the cost of using square wood. Take the main rib material (1 or 2 square steel tubes) as an example:

[0117] If the rental period exceeds 1136 days, the cost is better when the main rib material (2 square steel tubes) is used; otherwise, the cost is better when the main rib material (1 square steel tube) is used.

[0118] In the above embodiment, the main flute selection planning is only a comparison planning under ideal conditions. In actual application, there are the following problems:

[0119] 1. During on-site construction, there are large panel sizes that do not meet the formwork erection conditions with large vertical pole spacing (1500 / 1500mm, 1800 / 1800mm), which is more common on the ground standard layer;

[0120] 2. The 1500 / 1500mm and 1800 / 1800mm pole spacings are difficult to misalign with the 600, 900, and 1200mm pole spacings under the beams. The larger pole spacing under the board will increase the number of poles under some beams to ensure reliable connection of the frame.

[0121] 3. The distance between the vertical poles of 1500 / 1500mm and 1800 / 1800mm is relatively large, and there is no fulcrum for the scaffold workers to set up, which makes it difficult to set up the scaffolds.

[0122] 4. The weight of square steel pipes is twice that of fastener steel pipes, which increases the difficulty for scaffold workers to carry and erect.

[0123] Field application

[0124] 1. Basement formwork: Based on the thickness and size of the on-site slab, and taking into account the theoretical cost and on-site safety, the vertical pole spacing of 1200 / 1200mm is selected as the main spacing for the basement formwork.

[0125] 2. Standard floor formwork on the ground: Taking the standard floor of Building 6# as an example, draw a formwork layout diagram and conduct cost comparison.

[0126] Taking the standard floor of Building 6# (mostly prefabricated panels) as an example, the spacing of the vertical poles under the unified beam (joist form) is 900mm. The spacing of the vertical poles under the slab is divided into small spacing (600-900mm, the main ribs use double-fastener steel pipes) and large spacing (1500-1800mm, the main ribs use double-sided steel pipes). The vertical pole layout is drawn separately. Figure 1-2 As shown:

[0127] The total number of poles in the small-pitch pole arrangement is 339; the total number of poles in the large-pitch pole arrangement is 263, which means that the large-pitch arrangement has 76 fewer poles than the small-pitch pole arrangement.

[0128] After analysis, the above two pole arrangement schemes have differences in the number of poles under the slab only in large-span rooms:

[0129] 3.8*5.0m (3 blocks), large bay (3*4 rows) and small bay (5*6 rows) reduce 18 poles;

[0130] 2.9*4.1 meters (1 block), large bays (3*3 rows) and small bays (4*5 rows) reduce 11 vertical poles;

[0131] 2.8*3.2 meters (2 blocks), large bays (3*3 rows) and small bays (4*4 rows) reduce 7 vertical poles;

[0132] 2.8*2.4 meters (2 blocks), large bays (3*2 rows) and small bays (4*3 rows) reduce 6 vertical poles;

[0133] 2.6*3.3 meters (1 block), large bay (3*3 rows) and small bay (4*4 rows) reduce 7 poles;

[0134] 2.5*2.35 meters (1 block), large bay (3*3 rows) and small bay (4*3 rows) reduce 3 vertical poles;

[0135] 2.2*2.5 meters (1 block), large bay (2*2 rows) and small bay (3*4 rows) reduce 8 poles;

[0136] 3.5*2.2 meters (1 block), 6 poles are reduced for large bays (3*2 rows) and small bays (4*3 rows).

[0137] In summary, the number of vertical poles under the slab is reduced by 115 in large bay arrangement compared to small bay arrangement;

[0138] Combined with the comparison of the total number of vertical poles and the number of vertical poles under the beams, the number of vertical poles under the beams in the large bay arrangement increases by (115-76) = 39 compared to the small bay arrangement.

[0139] Cost comparison of standard floors above ground

[0140] Selection background:

[0141] 1. The formwork under the standard floor beam adopts the form of a supporting beam, so the length of the vertical bar under the beam is the same as the length of the vertical bar under the slab. The length of the vertical bar is tentatively set at 2.6 meters, and the number of horizontal bars is 3 rows;

[0142] 2. The joists under the beams are arranged at a fixed spacing of 300. The cost of the horizontal bars and joists under the beams of the two schemes is not considered in this comparison;

[0143] 3. Standard floors are mostly prefabricated panels, and the cost of square timber and formwork is not considered in this comparison.

[0144] In summary, the cost difference between the large bay selection scheme and the small bay selection scheme is shown below:

[0145] 1. Reduce 76 poles = 76*2.6*0.00555*3.5 = 3.84 yuan / day

[0146] 2. Reduce horizontal bars = (3*(4.2*2+3.3*2)

[0147] +(3.6+2.1*2)+2*(2.7+2.1)+2*(1.8+2.1)+(2.7+2.1+1.8+1.8+1.5*2

[0148] 2.7+1.5))*0.00555*3.5=2.78 yuan / day

[0149] 3. The length of the main rib of the large bay = (3*5*3+3*4.1+3*3.2*2+3*2.4*2+3*3.3+3*2.35+2*2.5+3*2.2)*2 = 238.9 meters

[0150] Length of main rib of small bay = (5*5*3+4*4.1+4*3.2*2+4*2.4*2+4*3.3+4*2.35+3*2.5+4*2.2)

[0151] *2 = 350.2 m

[0152] Cost saving = 350.2*0.0033*3-238.9*0.00685*3.5 = -2.26 yuan / day, total cost saving

[0153] =3.84+2.78-2.26=4.36 yuan / day

[0154] The main flute selection plan is only a comparison plan under ideal conditions. The following problems exist in actual applications:

[0155] 1. During on-site construction, there are large panel sizes that do not meet the formwork erection conditions with large vertical pole spacing (1500 / 1500mm, 1800 / 1800mm), which is more common on the ground standard layer;

[0156] 2. The 1500 / 1500mm and 1800 / 1800mm pole spacings are difficult to misalign with the 600, 900, and 1200mm pole spacings under the beams. The larger pole spacing under the board will increase the number of poles under some beams to ensure reliable connection of the frame.

[0157] 3. The distance between the vertical poles of 1500 / 1500mm and 1800 / 1800mm is relatively large, and there is no fulcrum for the scaffold workers to set up, which makes it difficult to set up the scaffolds.

[0158] 4. The weight of square steel pipes is twice that of fastener steel pipes, which increases the difficulty for scaffold workers to carry and erect.

[0159] On-site application,

[0160] 1. Basement formwork: Based on the thickness and size of the on-site slab, and taking into account the theoretical cost and on-site safety, the vertical pole spacing of 1200 / 1200mm is selected as the main spacing for the basement formwork.

[0161] 2. Standard floor formwork on the ground: Taking the standard floor of Building 6# as an example, draw a formwork layout diagram and conduct cost comparison. In summary,

[0162] 1. The theoretical calculation table is applicable to large basement bays and serves as a reference for formwork measurement.

[0163] 2. Square steel pipes have better material properties than fastener-type steel pipes. As the main rib material, they can free up more performance of the disc-type uprights and reduce the amount of disc-type frame erection.

[0164] 3. The performance of the 40*90mm square wood secondary fluting material restricts the final cost calculation. The increase in the spacing between the buckle and the uprights will lead to a decrease in the spacing between the secondary flutes. The cost calculation process needs to balance the amount of buckle, main flute and secondary flute materials.

[0165] 4. During the erection of large-spacing discs, there are difficulties such as the square steel pipes being too heavy and the scaffold workers having no fulcrum.

[0166] 5. The 1500 / 1500mm and 1800 / 1800mm vertical pole spacing is difficult to misalign with the 600, 900 and 1200mm vertical pole spacing under the beam. The larger vertical pole spacing under the plate will increase the number of vertical poles under some beams to ensure reliable connection of the frame.

[0167] 6. The spacing between vertical poles for small openings on the ground floor should be selected according to the actual size of the room.

[0168] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for replacing wood with steel and supporting formwork poles, characterized in that: The following steps are involved: Main rib selection and planning, formwork stand spacing determination, formwork theoretical quantity calculation, actual construction application and cost comparison; Main rib selection planning: select appropriate main rib material according to the thickness and load requirements of the floor slab; Determine the formwork pole spacing: Calculate and determine the economically reasonable pole spacing based on the floor slab thickness and main rib material properties; Formwork theoretical quantity calculation: Calculate the formwork material requirements under specific floor area and floor height conditions using the formwork theoretical quantity calculation principle; Practical application adjustments: Taking into account on-site construction conditions and actual challenges, the theoretical calculation values ​​are adjusted to ensure construction feasibility and safety; Basement formwork erection: When erecting the basement formwork, select the appropriate spacing between the vertical poles and adjust it according to the thickness and size of the slab; Formwork erection for standard floors above ground: For standard floors above ground, draw a formwork layout diagram and erect formwork according to the different requirements of precast slabs and cast-in-place slabs; Cost comparison: Compare the formwork costs of different main rib materials and vertical pole spacing options, and select the most cost-effective option.

2. A steel-replacing-wood and formwork support pole construction method according to claim 1, characterized in that: The following steps are involved: (5) Determine the load: Calculate the uniformly distributed load on the floor slab, including dead load and live load; q = uniformly distributed load on the floor Determine the allowable stress: Determine the allowable stress value based on the characteristics of the pole material; Determine the bearing capacity of the pole A is the cross-sectional area of ​​the pole, f is the yield strength of the material, and g is the safety factor, with g ranging from 1.5 to 2.5; (6) Calculation of the bearing capacity of the pole: Calculate the bearing capacity based on the geometric dimensions and material properties of the pole; Calculate the maximum allowable spacing: Use the mechanical model to calculate the maximum allowable spacing of the poles while meeting safety requirements L is the maximum allowable spacing between the vertical poles while meeting the bearing capacity requirements (7) Consider stability factors: The stability of the pole is affected by compression buckling, lateral support conditions and slenderness ratio factors; K is the effective length coefficient of the pole; E is the elastic modulus of the material, I is the moment of inertia of the pole section, Kcr is the critical load factor, f y is the yield strength of the material; (8) Considering the construction specifications, there are specific requirements for the spacing between poles as follows: L z =min(L,L w ,L g ), L z is the final spacing, Lw is the stability, and Lg is the specification requirement.

3. A steel-replacing-wood and formwork support pole construction method according to claim 1, characterized in that: The main corrugated material is preferably square steel tube or fastener type steel tube.

4. A steel-replacing-wood and formwork support pole construction method according to claim 1, characterized in that: The vertical pole spacing of 1200 / 1200mm is used as the main spacing for the basement formwork erection.

Images