Ten key points for quality control of steel structure projects
Ten key points of structural engineering quality control
Steel structure is one of the more common forms of structures in modern construction projects. The application of steel structure engineering construction technology is becoming more and more widespread in China, and the many superiorities possessed by steel structure are also valued, and the application of steel structure engineering has increased as a result. In this paper, we analyze the construction technology requirements of steel structure engineering, so as to strengthen the technical application and management of steel structure engineering and ensure the safety and reliability of the whole steel structure engineering.
The drawings are the basis for the construction of steel structure engineering, and the technical person in charge of the project should organize the relevant technical personnel to review and digest the drawings, the purpose of which is to make the construction unit and each participating unit familiar with the design drawings, understand the engineering characteristics and design intent, find out the technical problems that need to be solved, and develop solutions; secondly, in order to solve the problems in the drawings, reduce the errors in the drawings, and put the quality of the drawings The hidden problems are eliminated in the bud. At the same time, we should do a good job of technical delivery of steel structure, the combination of construction and design, the combination of steel structure lifting and civil construction, steel structure and concrete structure prefabrication. The following is a detailed introduction of the main points of the quality control of steel structure engineering.
I. Quality control of raw materials
1、Familiar with the drawings, summary of the problems in the drawings, to participate in the drawing review and design briefing; detailed records of the drawings of the main components of the materials used in the species, specifications, performance, etc. should comply with the current national standards and design requirements, and require the provision of product quality assurance, Chinese marks and test reports. This item is a mandatory provision, and must be strictly checked.
2, the beam and beam, beam and column used between the high-strength bolts and connection vice, ordinary bolts, rivets, self-tapping nails, anchor bolts, anchor bolts and nuts, etc. Its species, specifications, performance should be in line with the current national standards and design requirements, and require the provision of product quality certification documents, and test reports, the need for retesting, should be retested.
Second, the quality control of steel structure parts and components processing
According to the requirements of Party A, the supervisory unit should be stationed in the steel construction unit's factory to follow up and supervise the main points of control as follows.
1, the variety, specifications, performance of steel should be in line with the current national product standards and design requirements, and has been re-inspected.
2, steel cutting surface processing should be free of cracks, slag, delamination and size 1mm missing edges, according to the specification requirements with a magnifying glass inspection, as well as magnetic particle and ultrasonic control injury inspection, and 10% of the number of cutting surface random checks, and not less than three.
3, steel processing will produce deformation, in order to meet the requirements, must be corrected, according to the different materials used, when taking hot correction, heating temperature can not exceed 900 ℃, and then should be natural cooling; when using cold correction, according to 10% of the number of corrected pieces, random checks, and not less than three.
Third, the quality control points in the welding of steel components
1, welding material specifications, models, performance, etc. should comply with the current national product standards and design requirements, quality certification documents and inspection reports have been checked and qualified. This is a mandatory provision, must be strictly checked.
2, welding materials must be matched with the parent material, should comply with the provisions of JGJ81 "Technical Specification for Welding of Building Steel Structures", and according to its instructions for storage or baking storage, to provide baking records ledger.
3, the welders involved in welding must be licensed to work within the scope of their documents approved for welding, according to the certificate provided against its people to check are in line with the requirements; the mandatory provisions, must be strictly checked.
4、The welding process must be assessed before welding, according to the report to determine the welding process.
5, on the welding seam of steel members, the design requirements of the full weld through the weld, the need for internal defect inspection, the use of ultrasonic and radiation flaw detection, the implementation of standards and sampling ratio according to GB11345 and GB3323 implementation, the mandatory provisions must be implemented.
6, weld surface defects: ordinary weld surface shall not have cracks, weld tumor and other defects; one, two weld surface shall not have porosity, slag, solitary pit cracks, arc abrasion and other defects; one weld shall not have bitten edge, not welded full, root shrinkage and other defects. Check with magnifying glass, welding seam gauge and steel ruler, and sample check by 10% of the number of components, and not less than 3 pieces.
Fourth, the quality control of pre-assembly of steel components
High-strength bolts and ordinary bolt connections should be inspected using a pilot hole tester, when using a pilot hole tester smaller than the diameter of the hole 1.0mm, the pass rate should not be less than 85%, when using a pilot hole tester larger than the diameter of the bolt 0.3mm, the pass rate is 100%. It is strictly prohibited to use gas cutting and welding punching and other methods on site.
V. Quality control of the assembly of steel components
1、The truss of crane beam and crane beam, check the member upright, after supporting at both ends, check with level and steel ruler, should not be deflected, the provision is mandatory, must be strictly checked.
2, end milling accuracy, end milling flat member length deviation of ± 2.0mm, milling plane flatness of 0.3mm; with steel ruler, plug ruler, angle ruler according to the number of milling plane 10% random checks, and not less than 3.
3、The outline dimensions of steel members should be checked in full, with steel ruler.
Sixth, the quality control of the installation process of single-layer steel structure
When the anti-corrosion coating is completed, the steel members and come in one after another, the appearance and geometry dimensions of each batch of incoming members shall be inspected and acceptance records shall be made, and the next shall be installed in the following order.
1、Installation of footing anchor bolts, before the steel members are delivered, the civil construction unit has been completed according to the drawing requirements, before the specifications of anchor bolts, axis, elevation, spacing are accepted, and the anchor bolts have been retested and qualified, the concrete strength should meet the lifting requirements, the longitudinal and transverse center lines of the steel column on the surface of the bearing platform are all played and have been reviewed and qualified.
2, steel column centerline and elevation reference points should be marked complete, (this is a mandatory provision), and then the steel column lifting, if the plant is long, should be installed from one end to the end of the construction joints, when there is inter-column support must be installed in place, together with the roof ties and other sub-components together with the end of installation.
3, steel column installation after correction: require the construction unit for each steel column according to the design and specification requirements one by one for elevation and verticality testing, the method is: a level meter aligned with the reference point to measure the elevation; with two latitude and longitude meter in two different directions to measure the verticality, until adjusted. Then randomly check by 10% of the number of components, and not less than 3, after passing the column foot anchor bolts final screwing in place.
4、The order of installation of roof steel beam and secondary members is the same as that of steel column: they should be installed one bay by one bay, and after the first bay and the second bay form a stable structural unit, then four steel wire ropes are used for symmetrical fixing, and finally the crane can be removed and the third and fourth bays are installed immediately until all are finished. Eight, the construction quality control of fasteners
Fastener installation is divided into: ordinary fastener connection and high-strength bolt connection, in the process of steel structure installation, the installation of this process should be carried out at the same time. The control points are as follows.
1, ordinary fasteners: should meet the design requirements, has checked its warranty information, when the design requirements, should be tested in accordance with the current national standard GB3098, in general, as long as the length of the bolt after tightening, revealing two silk buckle on it.
2, high-strength bolts: before installation according to the requirements of the drawings for each specification bolt sampling retest, each specification to take 8, for tensile and torsion test. The torque wrench used must be sent to the testing department for testing and calibration, and can only be used after passing.