In recent years, with the rapid development of building steel structure technology and the degree of mechanization increasingly improved, and because of the steel structure tensile, compressive strength is relatively high, small section, light weight, good structural performance, construction speed, small environmental pollution, so the steel structure engineering is applicable to a variety of structural forms and places.Therefore, light steel structure engineering has been widely used.How to do a good job of steel structure safety and quality control is an urgent matter of the moment, to do a good job from the source of quality control, which requires us to deeply understand the causes of common accidents of steel structure, according to these reasons for analysis, effective governance, to ensure the safety of the project.This paper summarizes the common quality accidents of steel structures and analyzes their causes.
1. Common quality accidents in grid construction
(1) bending deformation or partial fracture of the bar.
(2) failure of weld connection of bar sealing plate or cone head.
(3) deformation or fracture of joints.
(4) the weld is not full or has bubbles, slag inclusion, micro cracks exceeding the specified standards.
Second, portal frame engineering common quality accidents
(1) deformation and distortion of main components.
(2) the embedded parts do not meet the requirements of drawings and specifications, the height difference exceeds the limit, and the spacing exceeds the limit.
(3) the overall perpendicularity of the steel frame and the overall plane bending are out of tolerance. The hole position of the plate at the end of the beam and column is not corresponding and the size is out of alignment.
(4) the welding seams of the main stress joints are not full or have bubbles, slag inclusion, micro cracks exceeding the specified standards, etc.
The main reason
I. design reasons
(1) unreasonable selection of structural form, unreasonable cross section matching of members, neglect of the influence of initial bending, initial eccentricity and secondary response of members, low calculation of load and missing calculation or improper load combination during design.
(2) unreasonable material selection.
(3) the selection of calculation methods, assumptions and computer programs failed to find errors.
(4) wrong or incomplete drawings.If the dimension labeling is confused, the design description is not clear, and there are omissions to the material, process requirements, construction procedures and special requirements.
Ii. Processing reasons
(1) disordered management, mixed use of different specifications, steel Numbers and materials.
(2) the blanking size of components is wrong, and the length-to-thinness ratio of components does not meet the design requirements.
(3) no liner is added to the weld seam or welded according to the design requirements when the mesh frame members are not cut or butt.
(4) connection high-strength bolts are unqualified.
3. Reasons for installation of network frame
(1) uneven support points and unreasonable forces during ground assembly, accumulation of errors during assembly, errors of individual members, resulting in changes in forces, resulting in deformation of network frames or individual members.
(2) the welding process and sequence are wrong, resulting in welding stress and deformation.
(3) when the overall hoisting, the selection of lifting point is not reasonable, there is no check on the lifting point of the counterforce check, bar overstress check, deflection check, the excessive stress of the necessary reinforcement measures.
(4) during the overall lifting, the lifting speed of each lifting point is different, and the displacement and height difference exceed the allowable range, resulting in deformation and damage.
Four, door type rigid frame installation reason
(1) the mat is placed unevenly when the long components are transported and stacked, which will result in deformation and distortion if placed for a long time.
(2) the position of embedded bolts is not correct, and there is no retaking or correction during installation, resulting in the deformation and distortion of columns and beams, as well as the overall perpendicularity and plane bending of the steel frame.
(3) the hole position of the end plate of the beam and column is not corresponding or misplaced, the end plate is not aligned when installation, and the bolt is not tightened in order when tightening.
(4) failure to operate according to welding procedures or technical problems of welders during on-site welding results in incomplete welding seams or air bubbles, slag inclusion and micro-cracks.
Described above, is common in light steel structure engineering quality accidents and causes, light steel structure engineering is many different professional staff work together to build, including production, design and site construction personnel, etc., the construction of a light steel structure engineering need we work together, so in order to let the light steel structure engineering safety, let us hand in hand together!