Steel is an essential building material widely used in various construction projects. However, steel structure construction involves many complex processes and critical links, requiring strict quality control to ensure construction safety and project quality.

steel structure construction

Critical points of steel structure construction

Quality control of embedded bolts

1. When constructing foundation-embedded bolts, familiarize yourself with the drawings, understand their intent, and make an installation template.

2. The embedded bolts are positioned on the main bars and formwork of the column using the installation template and steel bars to ensure that the embedded bolts will not be displaced during the concrete pouring construction of the civil construction.

3. Control the spacing and height between bolts within the allowable error range, protecting the bolt threads from damage during concrete pouring.

4. After the civil engineering project is completed, use theodolite and level to recheck the elevation and axis of the anchor bolts, keep records, and submit them to the following process for acceptance.

Component production quality control

Steel structure construction usually involves two stages: factory production and on-site installation.
The general production process of steel structures is divided into: lofting → blanking → paneling → cutting → assembly → submerged arc welding → drilling → assembly → correction and forming → riveter parts blanking → production and assembly → welding and welding inspection →, prevention Rust treatment, painting, numbering → components are accepted and shipped from the factory.
In the production of steel structures, the key processes should be grasped for quality control based on the steel structure production process, such as controlling the processing of critical parts, the processes and measures of the main components, the processing equipment, and process equipment used, etc.

Steel Structure Construction for Welding Quality

1. Before welding the steel structure, the qualification certificate of the welding rod must be inspected and used according to the instructions. The welder must have a work permit.
2. There shall be no cracks or welding burrs on the surface of the weld. The first- and second-level welds shall not have pores, slag inclusions, or arc crater cracks. The first-level weld shall not have defects such as undercuts and under-welding. The seams shall undergo non-destructive testing as required, and the welder’s stamp shall be inspected at the specified welds and locations.
3. Unqualified welds shall not be processed without authorization. The modification process shall be determined before processing. The number of weld repairs at the same part should not exceed two times.

Steel structure Connection

1. When tying and overlapping, the number of stirrups for each column should be calculated according to the spacing required by the drawing. The stirrups should first be placed on the overlapping bars extending from the lower layer. Then, the column reinforcements should be erected.
2. Within the overlapping length, there should be no less than three fasteners on the steel bars, and the fasteners should be toward the inside of the column to facilitate the upward movement of the stirrups.
3. When a double-layer steel mesh is used as the foundation floor, steel support feet or concrete support feet should be set under the upper layer of steel mesh to ensure the correct position of the steel bars.
4. If the column’s main bars are overlapped with plain round steel bars, the corner hooks should be at an angle of 45° with the formwork, and the hooks of the middle steel bars should be at an angle of 90° with the formwork.
5. When the cast-in-place column is connected to the foundation by inserting bars, the stirrups should be one diameter smaller than the column bars to facilitate connection. At the same time, the insertion position must be firmly fixed to avoid deviation of the column axis.

Components quality control of steel structure construction

1. The quality of the components should be inspected before steel structure construction. If the permanent deformation and defects of the components exceed the allowable value, they should be dealt with.
2. When installing steel columns, check whether the pads under the column bottom plate are firmly padded and leveled to prevent the anchor bolts under the column bottom plate from becoming unstable.
3. Whether the control column is vertical and displaced. Temporary support measures should be taken before the structure forms a stable system during installation.
4. When the steel structure is installed to form a spatially fixed unit and has passed the acceptance inspection, the construction unit must promptly pour and compact the space between the column bottom plate and the top surface of the foundation with expanded concrete.
5. Check the verticality and overall plane bending of the main structure of the steel structure.

Fastener connection

1. Pay attention to the processing quality of the friction surface of high-strength bolts and the protection before installation to prevent contamination and corrosion. Before installation, conduct an anti-slip coefficient test on the friction surface of high-strength bolts, check the factory certificate and batch number of high-strength bolts, and regularly conduct axial force tests on high-strength bolts of different batch numbers.
2. Installing high-strength bolts requires free penetration; no knocking or reaming is allowed. Therefore, certain tire frame molds should be prepared when making steel structures to control their deformation, and practical fixing measures should be taken during component transportation to ensure their dimensional stability.
3. During steel structure construction, the contact surface of the plate stack should be smooth, the contact surface must be better than 75%, and the edge gap must not be greater than 0.8mm.

Strictly control and inspect the high-strength bolt installation process, including operating sequence, installation method, tightening sequence, initial tightening, and final tightening. The torque wrench for tightening bolts should be calibrated. After the final tightening, each screw should be inspected one by one, and any under-tightened or over-tightened screws should be re-tightened or replaced.

Rust removal and painting projects

1. Construction personnel must use different methods of rust removal according to the drawing requirements and levels.
2. The quality of the painting project should be controlled so that before painting the steel structure, there should be no foreign matter, such as welding slag, oil stains, water, and burrs, on the surface of the painted components. The number of painting passes and thickness should meet the design requirements.
3. The coating materials must have certificates, and the fire retardant coating project must be carried out by a construction unit approved by the fire department.

Key points to note in steel structure construction:

1. If a gutter exists, the tie rod cannot be designed close to the top of the column. Otherwise, it may be impossible to install the downpipe.

2. The position of high-strength bolts must be reasonable, and the construction space of the twist breaker and torque wrench must be considered. During installation, the Torx head of the high-strength bolt cannot be twisted because the space is too small, and the twist breaker and torque wrench cannot be in place. Or the high-strength bolts cannot be tightened.

3. use a symmetrical bolt arrangement method for high-strength bolt connecting plates if possible.

4. If the light steel structure has brick walls to maintain, it must be prepared in advance with the construction and civil construction units.

5. The connection between wind columns and steel beams should be made with spring plates as much as possible because the beams in the middle span have a relatively large deflection after installation. The roof will be uneven if the gable beams are connected to the wind-resistant columns with bolts.

6. The braces between the upper and lower adjacent purlins of the window frame are not appropriately arranged, and their ends conflict with the frame.

7. Anti-condensation paint should be painted under the gutter, a polyurethane insulation layer should be sprayed, or other insulation treatments can be used.

In conclusion

Quality control of steel structure construction is crucial. Only by strictly executing the construction process according to the requirements and paying attention to various details and precautions can the safety, reliability, and high quality of the steel structure project be ensured.