Although the steel structure construction is fast, short period, high strength, easy to prefabricate and install. However, the quality of steel structure engineering is also drawing more and more attention, so the construction should strengthen the quality control of steel structure engineering construction.
1.Quality control of pre-buried bolts
a. Construction of the foundation pre-buried bolts first familiar with the drawings, understand the intent of the drawings, should be made to install the formwork.
b. Pre-buried bolts with the installation template and steel positioning in the column of the main reinforcement and template to ensure that the pre-buried bolts are not displaced by the construction of civil pouring concrete.
c. Control the spacing between the bolts, height can be controlled within the allowable error; protect the bolt fillet from being damaged during the concrete pouring.
d. After the completion of the civil engineering, use the latitude and longitude meter and level meter to review the elevation and axis of the ground bolts, and make records, and hand them over to the next process for acceptance.
2.Quality control of member fabrication
The construction of steel structure project usually goes through two stages: factory fabrication and on-site installation.
The general production process of steel structure is divided into the following: placing samples → placing materials → assembling plates → cutting → assembling → submerged arc welding → drilling → assembling → corrective molding → riveting spare parts placing materials → production and assembly → welding and welding inspection → antirust treatment, painting, numbering → member acceptance factory.
In the steel structure fabrication, according to the steel structure fabrication process, key processes should be seized for quality control, such as control of the processing of key parts, the process of the main steel structure components, measures, the processing equipment used, process equipment, etc.
3.Welding project quality control
a.Before welding the steel structure, the certificate of conformity of the welding rod should be checked, used according to the requirements of the manual, the welder must be licensed to work on the certificate.
b.The surface of the weld shall not have cracks, weld tumor, one or two weld shall not have porosity, slag, arc pit cracks, a weld shall not have biting edge, not full welding and other defects, one or two weld according to the requirements of nondestructive testing, in the specified welds and parts to check the welder's steel seal.
c.Unqualified welds shall not be handled without authorization, set out to modify the process before processing, the same part of the weld should not be reworked more than 2 times.
4.Quality control of member installation
a.Before the installation of steel structure, the quality of the components should be checked, and the permanent deformation and defects of the components should be handled when they exceed the allowed value.
b.Steel column installation should check whether the pad iron under the column base plate is solid and level to prevent the footing bolts under the column base plate from being unstable.
c.Control whether the column is vertical and has no displacement, installation works, before the structure has formed a stable system, should take temporary support measures.
d.When the steel structure is installed to form a space fixed unit, and after acceptance, the construction unit is required to promptly pour the space between the column base plate and the top surface of the foundation with expanded concrete for the second time to be dense.
e.Check the verticality of the main structure of the steel structure and the overall plane bending.
5.Fastener connection quality control
a.Pay attention to the processing quality of the friction surface of high-strength bolts and the protection before installation to prevent pollution and rusting. And the anti-slip coefficient test of the friction surface of high-strength bolts before installation, check the factory certificate of high-strength bolts, batch number, and do axial force tests on a regular basis for different batches of high-strength bolts.
b.The installation of high-strength bolts requires free penetration, no knocking and reaming. Therefore, the steel structure should be prepared in the production of certain tire frame mold to control its deformation, and take practical fixing measures to ensure its dimensional stability when the components are transported.
c.The contact surface of the plate stack should be flat in the process of steel structure installation, the contact surface must be greater than 75%, and the edge gap should not be greater than 0.8mm. The installation process of high-strength bolts, including the operation order, installation method, fastening order, initial screwing and final screwing should be strictly controlled and checked, and the torque wrench for screwing bolts should be calibrated. The final screwing should be checked one by one, and the unscrewed and over-screwed ones should be made up or replaced.
6.Rust removal and painting works
a.The construction personnel shall adopt different rust removal methods according to the requirements of the drawings and the level of rust removal.
b.The quality control of the painting project should be done so that before the steel structure is painted, the surface of the painted components shall not have foreign matter such as welding slag, oil, water and burr, etc., and the number of times and thickness of painting shall meet the design requirements.
c.There must be a certificate of conformity for the painting materials, and the fireproof coating painting project must be constructed by the construction unit approved by the fire department.