Detailed explanation of specifications for erectio

2022-07-22
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Scaffolding has long been common and is often used on construction sites. However, if the scaffold is not erected well, it will affect the safety of workers' lives, and even harm innocent people, with unimaginable consequences. So how much do you know about the specifications for the erection of external wall scaffolding? Now let's take a look at the detailed explanation of the specifications for the erection of external wall scaffolding

scaffolding has long been common and is often used on construction sites. However, if the scaffold is not erected well, it will affect the safety of workers' lives, and even harm innocent people, with unimaginable consequences. So how much do you know about the specifications for the erection of external wall scaffolding? Now let's take a look at the detailed explanation of the specifications for the erection of external wall scaffolding

detailed explanation of the specification for the erection of external wall scaffolding

I. construction scheme

1. Before the erection of scaffolding, the erection scheme should be determined according to the characteristics of the type of work and the construction process, which should include: foundation treatment, erection requirements, bar spacing, wall connecting rod setting position, connection method, and draw construction details and detailed drawings

2. If the erection height of scaffold exceeds the specification, it shall be calculated

(1) when the erection size of fastener type steel pipe scaffold meets the following table, the corresponding rod can no longer be designed and calculated. However, the bearing capacity of the foundation of wall connecting parts and vertical poles should still be designed and calculated according to the actual load and the construction drawings should be drawn

(2) when the erection height is 25-50m, the overall stability of the scaffold should be structurally strengthened. For example, the longitudinal diagonal bracing must be set continuously. If the horizontal diagonal bracing is increased, the strength of the wall connecting rod will be increased correspondingly, and the spacing will be reduced. In windy areas, for scaffolds with a height of more than 40m, considering the overturning force of the wind vortex, the horizontal wall connecting parts should be set, and there should be wall connecting measures to resist the overturning effect of the uplift, so as to ensure the safety of the scaffold

(3) when the erection height is more than 50m, double vertical poles can be used to strengthen or sectional unloading can be used. The scaffold and beam and slab structure can be lifted and pulled with steel wire rope along the full height of the scaffold, and part of the load of the scaffold can be transferred to the building; Or it can be erected in sections, and the load of each section of scaffold is transferred to the cantilever beam and frame protruding from the building, which has been designed and calculated

(4) the design and calculation of scaffold must comply with the relevant provisions of scaffold specifications and be approved by the technical director of the enterprise

3. The construction scheme of scaffold should be consistent with the type of scaffold erected on the construction site. When the type of scaffold is changed due to fixed reasons on site, the scaffold scheme must be modified again and approved before construction

II. Pole foundation

1. The pole foundation of scaffold shall meet the requirements of the scheme

(1) when the erection height is less than 25m, it can be tamped and leveled, and 125px thick board is paved on it. When the length is 2m, it is placed perpendicular to the wall; When the length is greater than 3m, it is placed parallel to the wall

(2) when the erection height is 25-50m, the foundation method should be designed according to the site endurance or the backfill should be compacted in layers. When the requirements are met, sleepers can be used to support the cushion, or 500px thick ballast can be paved on the foundation, on which concrete slabs are laid, and then 12-16 channel steel is paved upside down

(3) when the erection height is more than 50m, it should be calculated and the foundation method should be designed according to the ground resistance, or the lime soil foundation should be used at the depth of 1m below the ground, or the 50m thick concrete foundation should be poured, and the pillow support pad should be used on it

2. The base of fastener type steel pipe scaffold can be made of malleable cast iron and welded. When erecting, the wooden base plate should be paved, the base should be placed, and then the upright rod should be placed in the base. It is not allowed to place the upright rod directly on the wood plate, otherwise the stress state of the base plate will be changed. The setting of base plate under the base is conducive to load transmission. The test shows that adding wood base plate (plate thickness 125px, plate length ≥ 5000px) under the standard base can increase the bearing capacity of foundation soil by more than 5 times. When the length of the board is greater than 2 spans, it will help to overcome the uneven settlement between the two poles

3. When the upright is not buried, set vertical and horizontal sweeping poles 500px above the ground. The method of setting the bottom sweeping bar is the same as that of the large cross bar. Its function is to fix the bottom of the vertical bar and restrict the horizontal position and settlement of the vertical bar. From the test, the bearing capacity of the scaffold without the bottom sweeping bar has also decreased

4. When the wooden scaffold pole is buried, the sweeping pole can not be set. The buried depth is 30-1250px, the pit bottom should be compacted and padded with broken bricks, and the backfill in the pit should be compacted in layers

5. When the scaffold foundation is low, it should be considered that there are no drainage measures around. After the wooden scaffold pole is buried and backfilled, an earth pier should be left higher than the ground to prevent ponding below

III. The scaffold is tied to the building structure

1. When the scaffold height is less than 7m, the throwing support method can be used to maintain the stability of the scaffold. When the erection height is more than 7m and it is inconvenient to set the throwing support, it should be connected with the building

(1) the connection between the scaffold and the building can not only prevent the inward or outward overturning accidents caused by wind load, but also serve as the intermediate constraint of the scaffold, reduce the calculated length of the upright, improve the bearing capacity, and ensure the overall stability of the scaffold

(2) the spacing of wall connecting rods should generally be set according to the distance specified in the table. When the scaffold erection height is high and it is necessary to reduce the spacing of the wall connecting rods, it is more effective to reduce the vertical spacing than the horizontal spacing. From the load test of the scaffold, the bearing capacity of the wall connecting rods set in two steps and three spans is increased by 7% than that set in three steps and two spans

(3) the wall connecting rod should be close to the node and set from the first step of the large cross bar on the bottom floor

(4) the wall connecting rod should be set close to the main node, and the distance from the main node should not be greater than 300mm

2. The wall connecting rod must be connected with the building structure to ensure the bearing capacity

(1) the position of the wall connecting rod should be determined in the construction scheme, and the detailed drawing of the fabrication method should be drawn. It is not allowed to set it at will in the operation. It is strictly forbidden to remove the wall connecting rod during the use of scaffold

(2) the connection method between the wall connecting rod and the building can be made into flexible connection or rigid connection. Flexible connection can be embedded in the wall φ 8 reinforcement ring, use double strand No. 8 (φ 4) lead wire to connect with the scaffold body, and add supporting measures to limit the deformation of both sides inside and outside the scaffold. When the erection height of scaffold exceeds 24m, flexible connection is not allowed

(3) when erecting the scaffold, the wall connecting rod should be erected synchronously with other rods; When dismantling the scaffold, the wall connecting rod shall be finally dismantled when other rods are dismantled to the height of the wall connecting rod. Before the removal of the last wall connecting rod, the throwing support should be set first, and then the wall connecting rod should be removed to ensure the stability of the scaffold during the removal process

IV. the spacing between members and diagonal bracing

1. The spacing between members such as upright, large cross bar and small cross bar shall comply with the specifications and the requirements of the construction scheme. When the spacing needs to be increased at the door, it should be reinforced according to the specifications

2. The upright is the main load-bearing member of the scaffold, and the spacing should be set evenly, and the spacing cannot be increased, otherwise the bearing capacity of the upright will be reduced; The change of the step distance of the large cross bar also directly affects the bearing capacity of the scaffold. When the step distance increases from 1.2m to 1.8m, the critical load decreases by 27%

3. Diagonal bracing is an important measure to prevent the longitudinal deformation of scaffold. Reasonable setting of diagonal bracing can also enhance the overall stiffness of scaffold and improve the bearing capacity of scaffold by more than 12%

(1) each group of diagonal bracing spans 5 ~ 7 vertical poles (> 6m), and the included angle between the diagonal pole and the ground is 45 DEG 60° Between

(2) for single and double row scaffolds with a height of less than 24m, a group of diagonal braces must be set at both ends of the outer facade, which shall be set continuously from the bottom to the top with the erection of the scaffold; The spacing between the middle parts can be no more than 15m

(3) double row scaffolds with a height of more than 25m must be set continuously along the length and height of the outer facade

(4) the diagonal bridging rod should be connected with the vertical rod and the extended small cross bar, and the lower end of the bottom diagonal rod should be placed on the base plate

(5) the extension of diagonal bridging rods adopts lap joint, the lap length is not less than 0.5m, and two fasteners are set

4. Cross bridging. When the erection height of the scaffold exceeds 24m, in order to enhance the rigidity of the horizontal plane of the scaffold, diagonal rods can be added in the horizontal plane every 6 spans longitudinally at the corners and in the middle of the scaffold, making it “ It ” Glyph or “ X ” Glyph. In case of operation layer, it can be temporarily removed, and when it is transferred to other layers, it should be added in time

v. scaffold board and protective railing

1. Scaffold board is the working platform of construction personnel, which must be fully paved according to the width of scaffold, and the boards are close to each other. When butt joint is adopted, two small cross bars are set under the joint; When overlapping is adopted, the joint shall be in the direction of the loaded vehicle; The scaffold board of bamboo fence should be laid perpendicular to the main bamboo bar in the direction of the big cross bar, and should be butt tiled, and the four corners should be φ 1.2mm galvanized steel wire is fixed on the large cross bar

2. Bamboo, wood and steel scaffold boards can be used, and their materials should meet the specification requirements. Bamboo scaffold board shall adopt bamboo string board and bamboo fence board made of Moso bamboo or Nanzhu. The bamboo board must be firmly nailed without incomplete bamboo pieces; The wooden scaffold board should be 125px thick, non brittle wood (such as birch, etc.) without decay and splitting board; The steel scaffold board is made of 2mm thick plate, and it cannot be used if there is rust or crack

3. Where the scaffold board extends beyond the small cross bar by more than 500px, it is called the probe board. At present, most of the scaffold boards are not tied firmly with the scaffold. If the probe board is encountered, it may cause a fall accident. Therefore, the presence of the probe board must be strictly prohibited. When the operation layer does not need to be fully paved with scaffold boards along the length of the scaffold, guardrails and vertical nets can be used at the end to limit the working surface, and the probe board can be closed outside the working surface

4. The outside of the foot and hand trap should be set with a dense safety net as required, and the safety net should be set inside the outer row upright. The dense mesh net must be fastened to the scaffold tube at an interval of 1125px (each ring buckle interval) with the tether required by the closure head

5. In case of operation layer, protective bars and toe boards shall be set between the large cross bar outside the scaffold and the scaffold board according to the requirements of edge protection to prevent operators from falling and materials on the scaffold board from rolling down

VI. disclosure and acceptance

1. Before scaffold erection, the person in charge of construction shall make detailed disclosure in accordance with the requirements of the construction plan and in combination with the working conditions and team conditions on the construction site, and there shall be a specially assigned person for command

2. After the scaffold is erected, the person in charge of construction shall organize relevant personnel to participate in the inspection and acceptance item by item according to the construction scheme and specifications. It can be put into use only after it is confirmed to meet the requirements

3. Inspection standard: (it should be carried out in accordance with the requirements of the corresponding specifications)

(1) the longitudinal distance deviation of steel pipe upright is ± 50mm。

(2) the verticality deviation of steel pipe upright shall not be greater than 1/100h and not greater than 250px (H is the total height)

(3) fastening torque of fastener: 40-50n m. Not more than 65n m。 Spot check the installation quantity by 5%, and the unqualified quantity of fasteners shall not be more than 10% of the spot check quantity

(4) fastener fastening procedure directly affects the bearing capacity of scaffold. The test shows that when the torque of fastener bolt is 30n M, 40n When m, the bearing capacity of scaffold decreases by 20%

4. The inspection and acceptance of scaffolds shall be carried out in accordance with the specifications. Any non-compliance shall be rectified immediately. The inspection results and rectification shall be recorded according to the measured data and signed by the inspectors

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