First, general provisions of scaffolding
(1) According to the outer diameter of the vertical pole, scaffolding can be divided into standard type (B type) and heavy type (Z type). Scaffolding components, materials, and their manufacturing quality shall comply with the provisions of the current industry standard “Socket-type disc-type steel pipe support components” JG/T503.
(2) The pin connection between the rod end buckle joint and the connecting plate should not be pulled out after hammering self-locking. When erecting the scaffolding, it is advisable to use a hammer of not less than 0.5kg to hit the top surface of the pin no less than 2 times until the pin is tightened. After the pin is tightened, it should be hit again, and the pin should not sink more than 3mm.
(3) After the pin is tightened, the arc surface of the buckle joint end should fit the outer surface of the vertical pole.
(4) The scaffolding structure design should adopt different safety levels according to the type of scaffolding, erection height, and load. The classification of scaffolding safety levels should comply with the provisions of the following table.
Second, the construction requirements of scaffolding
(I) General provisions
(1) The construction system of the scaffolding should be complete and the scaffolding should have overall stability.
(2) The horizontal and diagonal bars of fixed length should be selected according to the vertical and horizontal spacing of the vertical bars calculated in the construction plan, and the vertical bars, bases, adjustable supports, and adjustable bases should be combined according to the erection height.
(3) The erection step of the scaffolding should not exceed 2m.
(4) The vertical diagonal bars of the scaffolding should not use steel pipe fasteners
(5) When the load design value of the standard (B-type) vertical bar is greater than 40kN, or the load design value of the heavy (Z-type) vertical bar is greater than 65kN, the pre-layer step of the scaffolding should be reduced by 0.5m compared with the standard step.
(II) Structural requirements of the support frame
(1) The height-to-width ratio of the support frame should be controlled within 3. For support frames with a height-to-width ratio greater than 3, anti-overturning measures such as rigid connection with the existing structure should be adopted.
(2) For support frames with a standard pitch of 1.5m, the vertical diagonal bars shall be arranged according to the support frame erection height, support frame model, and the design value of the axial force of the vertical pole, and the vertical diagonal bar arrangement form shall be selected.
(3) When the support frame erection height is greater than 16m, vertical diagonal bars shall be arranged in each span within the top pitch.
(4) The cantilever length of the adjustable support of the support frame extending out of the center line of the top horizontal pole or double-groove support beam shall not exceed 650mm, and the exposed length of the screw rod shall not exceed 400mm. The length of the adjustable support inserted into the vertical pole or double-groove support beam shall not be less than 150mm.
(III) Regulations for adjustable supports
(1) The length of the screw rod of the adjustable base of the support frame inserted into the vertical pole shall not be less than 150mm, and the exposed length of the screw rod should not be greater than 300mm. The center line of the bottom horizontal pole as the sweeping pole shall not be greater than 550mm from the bottom plate of the adjustable base.
(2) When the support frame is erected at a height of more than 8m and there are existing building structures around it, it should be reliably tied to the surrounding existing structures every 4 to 6 steps along the height.
(3) The support frame should be equipped with horizontal scissor braces every 4 to 6 standard steps along the height and should comply with the relevant provisions of the steel pipe horizontal scissor braces in the current industry standard “Safety Technical Specifications for Fastener-Type Steel Pipe Scaffolding in Construction” JGJ130.
(4) When the support frame is erected in the form of an independent tower, it should be horizontally tied to the adjacent independent tower every 2 to 4 steps along the height.
(5) When a pedestrian passage with the same width as a single horizontal rod is set in the support frame, the first layer of horizontal rods and diagonal rods can be removed at intervals to form a passage for construction personnel to enter and exit and vertical diagonal rods should be set between the two side vertical rods orthogonal to the passage; when a pedestrian passage with a different width from a single horizontal rod is set in the support frame, a supporting beam should be erected on the upper part of the passage, and the type and spacing of the beam should be determined according to the load. The spacing between the vertical poles of the supporting beams of adjacent spans of the passage should be set according to calculations, and the supporting frames around the passage should be connected as a whole. A closed protective plate should be laid on the top of the opening, and a safety net should be set in the adjacent spans. Safety warnings and anti-collision facilities should be set at the opening for motor vehicles.
(IV) Scaffolding construction requirements (scaffolding)
(1) The height-to-width ratio of the scaffolding should be controlled within 3; when the height-to-width ratio of the scaffolding is greater than 3, anti-overturning measures such as guying or guy ropes should be set. Guying reference diagram
(2) When erecting double-row external scaffolding or when the erection height is 24m or above, the geometric dimensions of the frame should be selected according to the use requirements, and the step distance between adjacent horizontal poles should not be greater than 2m.
(3) The first-layer vertical poles of the double-row external scaffolding should be staggered with vertical poles of different lengths, and the bottom of the vertical poles should be equipped with adjustable bases or pads.
(4) When setting up a double-row external scaffolding pedestrian passage, a supporting beam should be installed on the upper part of the passage. The cross-section size of the beam should be determined according to the span and the load to be borne. Diagonal bars should be added to the scaffolding on both sides of the passage. A closed protective plate should be laid on the top of the opening, and safety nets should be installed on both sides; safety warnings and anti-collision facilities should be installed at the opening for motor vehicles.
(5) Vertical diagonal bars should be installed on the outer facade of the double-row scaffolding and should comply with the following regulations:
1. At the corners of the scaffolding and the ends of the open scaffolding, diagonal bars should be installed continuously from the bottom to the top of the frame;
2. A vertical or diagonal continuous diagonal bar should be installed every 4 spans; when the frame is erected at a height of more than 24m, a diagonal bar should be installed every 3 spans;
3. Vertical diagonal bars should be installed continuously from bottom to top between adjacent vertical bars on the outer side of the double-row scaffolding.
(6) The setting of wall ties shall comply with the following provisions:
1. Wall ties shall be rigid rods that can withstand tensile and compressive loads and shall be firmly connected to the main structure and frame of the building;
2. Wall ties shall be set close to the knot nodes of the horizontal rods;
3. Wall ties on the same floor should be on the same horizontal plane, and the horizontal spacing should not be greater than 3 spans. The cantilever height of the frame above the wall ties shall not exceed 2 steps;
4. At the corners of the frame or the ends of the open double-row scaffolding, they should be set according to the floors, and the vertical spacing should not be greater than 4m;
5. Wall ties should be set from the first horizontal rod on the bottom floor; wall ties should be arranged in a diamond shape or a rectangular shape; wall connection points should be evenly distributed;
6. When wall ties cannot be set at the bottom of the scaffolding, it is advisable to set up multiple rows of scaffolding and set diagonal rods to form an additional ladder frame with an outer inclined surface.
Installation and removal
(I) Construction preparation
(1) Before the scaffolding is constructed, a special construction plan should be prepared according to the construction site conditions, foundation bearing capacity, and erection height, and it should be implemented after review and approval.
(2) Operators should undergo professional technical training and pass professional examinations before taking up their posts with certificates. Before the scaffolding is erected, the operators should be briefed on technical and safety operations in accordance with the requirements of the special construction plan.
(3) Components that have passed the acceptance inspection should be classified and stacked according to type and specification and should be marked with quantity and specification nameplates. The stacking site for components should have smooth drainage and no water accumulation.
(4) The setting of embedded parts such as scaffolding wall connectors, brackets, cantilever beam fixing bolts, or lifting rings should be embedded in accordance with design requirements.
(5) The scaffolding erection site should be flat and solid, and drainage measures should be taken.
(II) Construction plan
(1) The special construction plan should include the following contents
① Preparation basis: relevant laws, regulations, normative documents, standards and construction drawing design documents, construction organization design, etc.;
② Project overview: overview and characteristics of the sub-projects with greater risks, construction plan layout, construction requirements, and technical guarantee conditions;
③ Construction plan: including construction schedule, material, and equipment plan;
④ Construction process technology: technical parameters, process flow, construction methods, operation requirements, inspection requirements, etc.;
⑤ Construction safety and quality assurance measures: organizational guarantee measures, technical measures, monitoring and control measures;
⑥ Construction management and operation personnel deployment and division of labor: construction management personnel, full-time production safety management personnel, special operation personnel, other operation personnel, etc.;
⑦ Acceptance requirements: acceptance standards, acceptance procedures, acceptance content, acceptance personnel, etc.;
⑧ Emergency response measures;
⑨ Calculation book and related construction drawings.
(III) Foundation and base
(1) The scaffolding foundation should be constructed according to the special construction plan and should be accepted according to the foundation-bearing capacity requirements. The scaffolding should be erected after the foundation is accepted. (2) Adjustable bases and pads should be used under the vertical poles on the soil foundation, and the length of the pads should not be less than 2 spans.
(3) When the foundation height difference is large, the vertical pole node position difference can be used to adjust the adjustable base.
(IV) Support frame installation and removal (formwork support)
(1) The location of the support frame vertical pole should be determined according to the special construction plan.
(2) The support frame should be set up according to the placement of the adjustable base of the vertical pole. It should be set up in the order of vertical poles, horizontal poles, and diagonal poles to form a basic frame unit, which should be expanded to form an overall scaffolding system.
(3) The adjustable base should be placed on the positioning line and should be kept horizontal. If a pad is required, it should be flat and without warping and cracked wooden pads should not be used.
(4) When the support frame is set up continuously on a multi-story floor, the upper and lower support poles should be on the same axis.
(5) After the support frame is erected, the frame should be inspected and confirmed to meet the requirements of the special construction plan before entering the next construction process.
(6) After the adjustable base and adjustable support are installed, the outer surface of the vertical pole should match the adjustable nut, and the difference between the outer diameter of the vertical pole and the inner diameter of the nut step should not be greater than 2mm.
(7) After the installation of the horizontal bar and the inclined bar pins, the pins should be checked by hammering, and the continuous sinking amount should not be greater than 3mm.
(8) When the frame is hoisted, the connection between the vertical poles should be increased with a vertical pole connector.
(9) During the erection and dismantling of the frame, small components such as the adjustable base, adjustable support, and base should be manually transferred. The hoisting operation should be commanded by a dedicated person and should not collide with the frame.
(10) After the scaffolding is erected, the vertical deviation of the vertical pole should not be greater than 1/500 of the total height of the support frame, and should not be greater than 50mm.
(11) The dismantling operation should be carried out according to the principle of installing first and dismantling later, or installing last and dismantling first. It should start from the top floor and dismantle layer by layer. It should not be carried out at the same time on the upper and lower floors, and it should not be thrown.
(12) When dismantling sections or facades, the technical treatment plan for the boundary should be determined, and the frame should be stable after the section.
(V) Scaffolding installation and dismantling
(1) The scaffolding poles should be accurately positioned and erected in accordance with the construction progress. The erection height of the double-row external scaffolding should not exceed two steps of the top wall tie, and the free height should not be greater than 4m.
(2) The wall tie of the double-row external scaffolding should be set up synchronously at the specified position as the scaffolding rises in height. It should not be installed late or dismantled arbitrarily.
(3) The setting of the working layer shall comply with the following provisions:
① The scaffolding boards shall be fully laid;
② The outer side of the double-row external scaffolding shall be equipped with footboards and guardrails. The guardrails can be arranged with two horizontal bars at the connection plates of the 0.5m and 1.0m of the vertical poles of each working surface, and a dense safety net shall be hung on the outside;
③ A horizontal protective net shall be set in the gap between the working layer and the main structure;
④ When steel scaffolding boards are used, the hooks of the steel scaffolding boards shall be firmly buckled on the horizontal bars, and the hooks shall be in a locked state;
(4) Reinforcements and diagonal bars shall be erected simultaneously with the scaffolding. When the reinforcements and diagonal braces are made of fastener steel pipes, they shall comply with the relevant provisions of the current industry standard “Safety Technical Specifications for Fastener-type Steel Pipe Scaffolding in Construction” JGJ130. (5) The height of the outer guardrail of the top layer of the scaffolding shall not be less than 1500mm above the top working layer.
(6) When the vertical pole is in a tension state, the sleeve connection extension part of the vertical pole shall be bolted.
(7) Scaffolding should be erected and used in sections and should only be used after acceptance.
(8) Scaffolding should be dismantled only after the unit project manager confirms and signs the dismantling permit.
(9) When dismantling scaffolding, a safe area should be marked out, warning signs should be set up, and a dedicated person should be assigned to supervise it.
(10) Before dismantling, the equipment, excess materials, and debris on the scaffolding should be cleared.
(11) Scaffolding dismantling should be carried out according to the principle of first installation and then dismantling, and the upper and lower parts should not be dismantled at the same time. The wall ties of the double-row external scaffolding should be dismantled layer by layer along with the scaffolding, and the height difference of the dismantling sections should not be greater than two steps. When the height difference is greater than two steps due to operating conditions, additional wall ties should be added for reinforcement.
(VI) Inspection and Acceptance
(1) The inspection and acceptance of scaffolding accessories entering the construction site shall comply with the following provisions:
① There shall be scaffolding product identification, product quality certificate, and type inspection report;
② There shall be scaffolding product main technical parameters and product instructions;
③ When there are doubts about the quality of scaffolding and components, quality sampling and whole frame testing shall be carried out;
(2) When one of the following situations occurs, the support frame and scaffolding shall be inspected and accepted:
① After the completion of the foundation and before the erection of the support frame;
② After each 6m height of the high formwork exceeding 8m is completed;
③ After the erection height reaches the design height and before concrete pouring;
④ After being out of use for more than 1 month and before resuming use;
⑤ After encountering strong winds of level 6 or above, heavy rain, and thawing of frozen foundation soil.
(3) The inspection and acceptance of the support frame shall comply with the following provisions:
① The foundation shall meet the design requirements and shall be flat and solid. There shall be no looseness or hanging between the vertical pole and the foundation. The base and support pads shall meet the requirements;
② The erected frame shall meet the design requirements. The erection method and the setting of diagonal bars, scissor braces, etc. shall meet the requirements of Chapter 6 of this standard;
③ The cantilever length of the adjustable support and adjustable base extending from the horizontal bar shall meet the requirements of the previous article;
④ The pins of the horizontal bar buckle joint, diagonal bar buckle joint, and connecting plate shall be tightened.
(4) Scaffolding inspection and acceptance shall comply with the following provisions:
① The erected frame shall comply with the design requirements, and the diagonal rods or scissor braces shall comply with the above provisions;
② The foundation of the vertical pole shall not have an uneven settlement, and the contact between the adjustable base and the foundation surface shall not be loose or suspended;
③ The wall connection shall comply with the design requirements and shall be reliably connected to the main structure and frame;
④ The hanging of the outer safety vertical net, the inner interlayer horizontal net, and the setting of the guardrail shall be complete and firm;
⑤ The appearance of the scaffolding accessories used in circulation shall be inspected before use, and records shall be made;
⑥ The construction records and quality inspection records shall be timely and complete;
⑦ The pins of the horizontal rod buckle joint, the diagonal rod buckle joint, and the connecting plate shall be tightened.
(5) When the support frame needs to be preloaded, the following provisions shall be met: (Preloading eliminates non-elastic deformation)
① A special support frame preloading plan shall be prepared, and safety technical instructions shall be given before preloading:
② The preloading load arrangement shall simulate the actual load distribution of the structure for graded and symmetrical preloading, and the preloading monitoring and loading classification shall comply with the relevant provisions of the current industry standard “Technical Regulations for Preloading of Steel Pipe Full-Span Support” JGJ/T194.
Post time: Feb-07-2025