Problems and solutions in the erection of steel pi

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Problems and solutions in the erection of fastener steel pipe scaffold

scaffold is the main construction tool in construction. For example, scaffolding is required for the masonry of brick walls, formwork erection, concrete pouring, decoration and painting, and the installation of structural components, so as to facilitate operation. If the scaffold is not erected in time, the construction period must be delayed; If the scaffold is not erected firmly, it is easy to cause casualties in construction. Therefore, the type selection, structure and erection quality of scaffold must be taken seriously

in view of the problems and unsafe factors existing in the design, construction and use of scaffolds at the construction site, in order to ensure the safety, reliability, economy and rationality of scaffolds and prevent casualties, the state has promulgated the industry standard "technical code for safety of steel tubular scaffold with couplers in construction" (jcj130-2001), which will be implemented on June 1, 2001

this specification is divided into 9 chapters and 183 articles. Among them, 24 are mandatory provisions. The main contents include: ① general provisions ② terminology symbols ③ components and fittings ④ loads ⑤ design calculation ⑥ structural requirements ⑦ construction ⑧ inspection and acceptance ⑨ safety management. It has been three years since the code was issued, but during the inspection, it was found that there were many irregularities in the implementation of many construction sites

I. quality standard of scaffold steel pipes and fasteners

1 Steel pipe: the specification stipulates that "the scaffold steel pipe shall adopt the No. 3 ordinary steel pipe specified in the current national standard straight seam welded steel pipe (gb/t3092). Its quality shall comply with the provisions of Q235-A steel in the current national standard carbon structural steel (gb/t700). The maximum mass of a single scaffold steel pipe should not be greater than 25kg, which should be used ф forty-eight × 3.5 steel pipe. The steel pipe surface should be straight and smooth, without cracks, scabs, delaminations, dislocation, hard bends, burrs, indentation and deep scratches. It is strictly forbidden to drill holes on the steel pipe, which should be coated with antirust paint

2. Fastener: the specification stipulates: "the fastener type steel pipe scaffold shall be made of malleable cast iron, and its material shall comply with the current national standard of hydraulic system control module steel pipe scaffold fasteners (gb15831)."

the quality of old fasteners should be checked before use. It is strictly forbidden to use those with cracks and deformation. Bolts with sliding threads must be replaced, and new and old fasteners should be treated with rust prevention

II. Problems in scaffold erection

1 There is no scaffold erection scheme and design calculation

during the inspection, it is found that some construction sites do not have erection schemes, and some have schemes, but the preparation is too simple, the calculation is wrong, and they have not been approved, so they cannot guide the on-site construction. What's more, the construction workers began to operate blindly after giving oral explanations to the operators, which seriously violated the provisions of "the requirements of scaffolding in the construction organization design" in the "specifications" and the "Regulations on the administration of work safety in construction projects" that special construction schemes must be prepared

2. The installation of the base does not meet the requirements of the specification

"the base plate should be a wooden base plate with a length of not less than 2 spans and a thickness of not less than 50cm, and channel steel can also be used". However, during the inspection, it was found that the lower end of the bottom pole of the scaffold at many construction sites was padded with only a small square wood or short wooden board. After the scaffold is erected and put into use, due to the gradual increase of load, combined with the influence of weather such as wind and rain, and the foundation is not compacted, it is easy to cause uneven settlement and deformation of the scaffold

3. The vertical pole joints were not staggered

the inspection found that during the erection process of some construction sites, the vertical poles were not carried out in strict accordance with the specifications, and the old method was still used to stagger the adjacent vertical poles, which did not meet the requirements that the joints of one vertical pole within the synchronization were staggered not less than 500mm in the height direction, resulting in insufficient frame strength

4. Bridging is not set according to the regulations

the specification stipulates that "double row scaffolds with a height of more than 24m shall be continuously set with bridging on the whole height of the outer side". During the inspection, it was found that there were many problems in some construction sites, such as insufficient span, discontinuity, non penetration, and non rooting. 3. Load frame: adopt guide light bar forming channel steel to fix the upper beam and worktable to form the frame structure, which could not stabilize the frame. In addition, the specification stipulates that the overlapping length of diagonal bridging rods is 1m, while some are only 400 ~ 500mm long, and only two fasteners are connected. Moreover, the scaffold has been erected for 5, 6 steps or all, and there is no cross bridging, but it can only be repaired after supervision

5. The setting of wall connecting parts is unreasonable

the Code stipulates that "rigid wall connecting parts must be used to connect the double row scaffold with a height of more than 24m to the building". During the inspection, it was found that some construction sites have too few wall connecting parts, and some use flexible joints, resulting in the instability of the frame. It was also found that the wall connecting parts of some construction sites were not reliably connected with the buildings, which simply did not work

6. The setting of small cross bars is unreasonable

the specification stipulates that the main node of the frame must coordinate the small cross bars, and some construction sites use the method of root separation, which only saves some materials, but has certain hidden dangers to the whole. In addition, the installation of small cross bars should also consider the laying of scaffold plates, and should not violate the specification that "the sum of the extension lengths of two scaffold plates should not be greater than 300mm"

7. The erection height of the scaffold is not high enough

the specification stipulates that "the top of the pole should be 1m higher than the parapet epithelium and 1.5m higher than the cornice epithelium". It is mainly to ensure the safety of construction personnel, but the inspection found that a small number of scaffolds on the construction site are not synchronized with the construction, which is lower than the operation level, and there are major potential accidents

8. The safety hanging is not standard

some construction sites have unqualified safety materials and unreliable binding. After the addition, the whitening phenomenon caused by the bending and stretching of products is small, the two are not connected, and the hanging is inconsistent. At the same time, there are too many dense holes and holes, which cannot play a protective role. Some construction sites do not set a safety level as required, and various protective measures are not implemented enough

9. The safety protection is not in place

the specification stipulates that "the scaffold board should be paved fully and stably, 120 ~ 150mm away from the wall, calculated from the scaffold board of the top operation layer, and it is advisable to pave a full layer of scaffold board every 12m". In fact, some construction sites failed to do so, and some even did not have scaffold boards, but only used square timber or steel formwork to replace scaffold boards. Some operating floors have frame plates locally, but there are many probe plates, which are not bound with lead wires, which is easy to cause personnel to fall

10. Inspection and acceptance

the specification stipulates that "the scaffold and foundation shall be inspected and accepted in the following stages: ① after the foundation is completed and before the scaffold is erected; ② before the load is applied to the working layer; ③ after each 10m ~ 13m height is erected; ④ when the design height is reached; ⑤ after the level 6 gale and heavy rain, after the cold area thaws; ⑥ shutdown for more than 1 month". During the inspection, it was found that some construction sites did not comply with the regulations. When checking the safety management data, the scaffold inspection and acceptance data can not be seen, but the scaffold has been put into use. Although there are inspection and acceptance materials on some construction sites, they are not accepted according to the stage, and there is no signature of the person in charge of erection and the acceptance personnel, which can not play the role of witness

III. safety management and use

1 The Code stipulates that "scaffold erection personnel must be professional scaffolders who have passed the examination according to the current national standard" management rules for safety technical examination of special operation personnel "(gb5036)". Realistically speaking, after the system reform and the establishment of the project management department in the construction enterprises, the flow of personnel and the retirement of old comrades have led to the shortage of professional scaffolders. Now the task of erecting the scaffold falls on the team or professional erection company undertaking the main construction. Although most of them have received the operation certificate after training, their technical level cannot meet the grade requirements

2. The specification stipulates that "formwork supports and pumped concrete steel pipes shall not be fixed on scaffolds". What about the actual situation? During the inspection, we found that many construction sites connect the formwork support, pumping concrete steel pipe, and fixed frame of material elevator with the scaffold. What's more, when painting inside and outside, the operators suspected that the wall was an obstacle and removed it without approval, which weakened the stability of the frame

IV. solutions

1 Strengthen the study and implementation of the specification

the construction management personnel of the project management department, especially the project manager, chief engineer, foreman in charge and safety officer, should strengthen the study of the specification, truly understand the specific requirements of each chapter and article, so as to prepare a scaffold erection (demolition) scheme and design calculation that conform to the actual situation, which is conducive to the supervision, guidance, inspection and acceptance of scaffold erection

2. Increase capital investment

the project department should have sufficient funds to purchase or rent various sizes of steel pipes, fasteners, bamboo scaffold boards, safety and other materials for scaffold erection, so as to ensure the continuity, integrity, safety and applicability of scaffold erection. In addition, professional teams with qualifications, strength and good technology should be selected to undertake the erection of scaffolds to ensure the erection quality

3. Carefully organize the inspection and acceptance

the chief engineer of the project department, the foreman in charge, and the safety officer should check in time during the scaffold erection process. If any unqualified product is found to produce friction force and affect the indication error, it should be rectified immediately until it is reworked and rebuilt. After the scaffold is erected, the project department shall organize relevant personnel to conduct acceptance in time, and it can be put into use only after it is qualified. Unqualified scaffolds shall not be put into use. The inspection and acceptance form shall be signed by the person in charge of erection and the acceptance personnel and stored in the safety management data file for future reference

4. Strengthen daily maintenance

after the scaffold is put into use, it is prone to problems due to the increase of load, the impact of climate change and human factors, which requires that there must be a special person responsible for maintenance, and the reinforcement of the reinforcement should be supplemented. In addition, the construction waste on the scaffold board should be cleaned frequently to reduce the load of the scaffold and ensure its safety

the project department shall conduct a comprehensive safety inspection on the scaffold every half month, and eliminate unsafe factors in time if found. The rectification opinions put forward by the competent department of the company and the superior safety supervision organization when inspecting the scaffold at the construction site shall be implemented and fed back in time

5. Establish a reward and punishment system

when signing the contract with the scaffold erection team, the project department should put forward clear requirements for the scaffold erection quality, indicate the reward and punishment terms or collect safety guarantee funds, and use economic leverage to urge them to undertake and perform safety obligations

in order to facilitate common progress and improvement, according to the requirements of the specification, combined with the erection, use and management of scaffolding, I put forward some questions and my own opinions for comrades' reference

Copyright © 2011 JIN SHI