The principles that must be followed in the design and construction of coupler-type steel pipe scaffolding indicate the scope of application of this specification. Compared with the original specification, it adds full-height scaffolding and full-height support frame, steel cantilever scaffolding, and other contents. Through a large number of full-height scaffolding and full-height support frame overall stability tests, more content has been added to the full-height scaffolding and full-height support frame parts.
(1) This is a regulation made in response to the problems existing in the design and construction of scaffolding on construction sites at present, aiming to ensure that the scaffolding project is economically reasonable, safe, and reliable, and to minimize the occurrence of casualties. It should be noted that when the construction and supervision review the plan, the design calculation content of the special plan must be carefully reviewed. The design calculation conditions should be consistent with the actual working conditions of the scaffolding.
(2) Explanation of the referenced standards: The steel pipes used in my country’s fastener-type steel pipe scaffolding are mostly welded steel pipes, which are cold-bent thin-walled steel. The material design strength f value and the stability coefficient φ value of the axially compressed member should refer to the current national standard “Technical Specification for Cold-bent Thin-walled Steel Structure” GB 50018; when hot-rolled seamless steel pipes are used in other cases, the current national standard “Steel Structure Design Code” GB 50017 should be cited.
2. Components
2.1 Steel pipes
2.1.1 Explanation:
(1) Tests show that the bearing capacity of the scaffolding is controlled by the stability conditions. The critical stress at the time of instability is generally lower than 100N/mm2. The use of high-strength steel cannot fully exert its strength. It is more economical and reasonable to use Q235A grade steel in the current national standard “Carbon Structural Steel” GB/T 700;
(2) Decades of engineering practice have proved that the use of electric welded steel pipes can meet the use requirements and the cost is lower than that of seamless steel pipes. For this reason, similar standards in Germany and the United Kingdom also adopt it.
(3) According to the current national standard “Welded Steel Pipe for Low-Pressure Fluid Transportation” GB/T 3091-2008 Article 4.1.1, Article 4.1.2, “Straight Seam Electric Welded Steel Pipe” GB/T 13793-2008 Article 5.1.1, Article 5.1.2 and “Welded Steel Pipe Dimensions and Unit Length Weight” GB/T 21835-2008 Section 4, the steel pipe should adopt the specification of ∮48.3×3.6. The European standard EN 12811-1:2003 also stipulates that the nominal outer diameter of the scaffolding pipe is 48.3mm.
(4) The length and weight of the steel pipe are limited to ensure construction safety and convenient transportation. Under normal circumstances, the maximum length of the horizontal bars of single-row and double-row scaffolding shall not exceed 2.2m, and the maximum length of other bars shall not exceed 6.5m.
2.2 Fasteners
2.2.1 According to the current national standard “Steel Tube Scaffolding Fasteners” GB 15831, the material of the fastener casting is malleable cast iron or cast steel. Fasteners are divided into right-angle fasteners, rotating fasteners, and butt fasteners according to the structural form. Right-angle fasteners are fasteners used for connecting vertical cross bars; rotating fasteners are fasteners used for connecting parallel or oblique bars; butt fasteners are fasteners used for butt connection of bars.
According to the current national standard “Steel Tube Scaffolding Fasteners” GB 15831, this standard applies to fasteners made of malleable cast iron or cast steel used in scaffolding, derricks, formwork supports, etc. with a nominal outer diameter of 48.3mm in steel pipes in construction projects, and also applies to fasteners used in municipal, water conservancy, chemical, metallurgical, coal and shipbuilding projects.
2.2.2 The provisions of this article are intended to ensure quality because the materials used for fastener bolts of various manufacturers in my country are quite different. Inspections show that when the bolt torque reaches 70N·m, most bolts have been stripped and cannot be used. Bolts and washers are fasteners of fasteners. When the bolt tightening torque reaches 65N·m, the fastener body, bolts, and washers must not be damaged.
2.3 Scaffolding
2.3.1 Aims to facilitate on-site transportation and safe use.
2.4 Adjustable support
2.4.1, 2.4.2 The regulations on adjustable supports are determined by the adjustable support failure test.
The adjustable support is the main component for directly transmitting the load of the full-height support frame. A large number of adjustable support tests have proved that the cross-sectional size of the adjustable support plate, the degree of bending deformation of the support plate, the welding quality of the screw and the support plate, the outer diameter of the screw, etc. affect the critical load of the adjustable support, and ultimately affect the critical load of the full-height support frame.
Adjustable support compression performance test: load at a uniform speed, when F is 50kN, the adjustable support shall not be damaged.
2.4.3 The conclusion of the test on the compressive performance of the adjustable support is that the thickness of the support plate is 5.0 mm, the failure load is not less than 50 kN, and 50 kN divided by the coefficient 1.25 is 40 kN. This is determined as the design value of the compressive bearing capacity of the adjustable support to ensure that the adjustable support will not be damaged.
Post time: May-28-2025