Bolt space frame engineering common problems

The steel space frame structure is a new type of structure that has been widely promoted and used in the past ten years. It is composed of bolt ball joints and steel pipe members and is a super statically indeterminate structure connected by high-strength bolts or welds. It has low steel consumption. Easy construction, and other advantages. With the rapid development of my country’s social economy, more and more steel space frame structures have been applied to large-span projects such as stadiums, airport waiting halls, train station waiting halls, gas stations, industrial plants, and large storage warehouses. middle.

The bolted ball space frame is a long-span steel space frame, which is more common in large-scale building construction. Using this space frame for large-span construction can effectively shorten the construction time, and the construction process is relatively simple, which can reduce the welding workload on the construction site. The welding error is small and easy to adjust. However, in recent years, with the popularization of the bolted ball space frame structure in buildings, the collapse of the space frame structure often occurs. Therefore, controlling the quality of the bolted ball space frame has a great impact on its stability and safety of the bolted ball space frame. Sexual enhancement plays an important role.

Common problems of bolt ball space frame engineering quality

1. Insufficient strength of high-strength bolts

The tensile strength of high-strength bolts in the bolt-ball joint space frame structure is the main factor affecting the bearing capacity of the joints, and its strength is related to the surface hardness. Therefore, the quality of high-strength bolts can be guaranteed through hardness control. The surface hardness test of high-strength bolts can be Ensure the quality of bolts.

2. The length of the high-strength bolt screwed into the bolt ball does not meet the requirements

During installation and construction, the thread length of the high-strength bolts screwed into the bolt ball has been hidden and cannot be measured, and the length of the screwed bolts cannot be judged. If the screwed-in length is insufficient, there will be safety hazards that directly affect the strength and stiffness of the space frame node connection.

3. The machining deviation of the bolt ball is too large

If the diameter, roundness, unbalanced milling surface and thread of the bolt ball are too large, the installation of the space frame will exceed the allowable deviation, so that the overall size and axis of the space frame will not meet the design requirements, affecting the mechanical performance of the space frame and reducing carrying capacity, causing safety hazards.

4. Dimension deviation of rod processing and verticality deviation of section

Common quality problems and hazards: the length of space frame rod processing, the verticality of the section to the tube axis, and the deviation of the nozzle axis exceed the regulations allowed by the specification, which will make it difficult to assemble and install the space frame, and there will be assembly and installation errors. On top or barely installed, resulting in large deviations in geometric dimensions and rod axes, which do not meet the design requirements, affect the mechanical performance of the space frame, and reduce the structural bearing capacity.

5. space frame installation deflection and axis deviation

After the general assembly of the bolted ball space frame is completed, the connection between the high-strength bolts and the ball joints is not fastened, there is a gap, loose, not tightened, and the overall deflection of the space frame exceeds the specification (that is, exceeds 1.15 times the design value), etc., which will reduce The strength and stiffness of the space frame structure as a whole affect the safety of use.

6. During the use of the space frame, the deflection is too large and the surface coating is peeled off and corroded

After the space frame structure is installed, additional loads are suspended during use, and the deflection increases, even exceeding the design value specified in the code by 1.15 times, causing serious safety hazards. Severe coating peeling and corrosion will appear on the surface of the space frame in about 5 to 10 years, resulting in poor appearance and threatening the safety of the space frame structure.

Quantity and method of steel space frame bolt ball detection

1. The types, specifications, and performance of bolt balls and the materials used to manufacture bolt ball joints should meet the current national product standards and design requirements.

Inspection quantity: full inspection.

Inspection method: according to the product quality documents, Chinese logo and inspection report.

2. The products in the bolted ball space frame must not have cracks and wrinkles.

Quantity to be inspected: spot checks 5% of the quantity corresponding to each specification, and not less than 3.

Inspection method: use a 10 times magnifying glass to observe and detect surface flaws.

3. The thread size of the bolt ball shall comply with the provisions of the current national standard GB/T 196 “Basic Dimensions of Ordinary Threads”, and the thread tolerance shall comply with the provisions of the 6H level accuracy in the current national standard GB 197 “Tolerances of Ordinary Threads”.

Quantity to be inspected: 5% of each specification shall be randomly inspected according to the quantity, and shall not be less than 3.

Inspection method: choose the basic form of standard thread.

4. The diameter, structural roundness, size, and allowable deviation of the centerline of the adjacent bolt holes on the bolt ball space frame shall comply with the provisions of GB 50205-2020.

Quantity for inspection: spot checks 5% of the quantity of each specification, and not less than 3.

Inspection method: check with calipers and dividing head instruments.

5. Allowable deviation of bolt ball processing

Quantity to be inspected: 10% of each specification shall be spot-checked, and shall not be less than 5

The importance of bolt ball space frame detection

Due to its excellent performance, the bolted ball space frame structure has a very fast development and application speed and a wide range. Since the bolt ball joint space frame does not require on-site welding, it is easy to manufacture, and the installation can be completed with a small amount of scaffolding, which saves materials and human resources, and shortens the construction period at the same time. The economic and technical benefits are remarkable. However, if you do not pay attention to it during the processing and installation process, various quality problems such as rod deformation and excessive deflection will occur, and the harm will be great. If you do not pay enough attention to eradicate it, it will damage the steel frame. The structure poses a great security risk.

Therefore, in the construction process of the bolt ballspace frame, no matter which installation method is selected, we must fundamentally pay attention to the safety of the quality of each workpiece in the project, control every detail, and test it in strict accordance with relevant standards.