Quality control of welding construction of building steel structure

With the continuous acceleration of the urbanization process, the construction industry continues to progress and prosperity, which greatly meets the needs of residents for construction projects and improves the quality of life of residents. Because of its good load-bearing function, steel structure is widely used in modern construction projects, which improves the stability and safety of building structures. In order to effectively ensure the construction quality of the building steel structure, the construction personnel need to increase the technical content of the construction process, and the construction personnel need to strengthen the supervision and management of the construction link, so as to effectively improve the construction quality of the building steel structure, and then improve the quality of the entire construction project.
1 Common quality problems of steel structure
In addition to the vertical load caused by gravity, the horizontal load caused by wind or earthquake is more important for high-rise steel structures. The building plane of multi-high-rise steel structure should strive to be simple, regular and symmetrical, and the facade should choose simple geometric figures that change evenly along the height. Multi-storey and high-rise structural systems include lateral force resistance system and gravity resistance system. The former mainly bears horizontal loads, while the latter mainly bears vertical loads, including dead weight and roof live loads. The structural design of multi-storey buildings mainly considers the anti-gravity system. The horizontal load plays a leading role in high-rise buildings, and the anti-lateral force system of the structure is more important. The steel frame in the structure is both the anti-lateral force system and the anti-gravity system. The lateral force resisting system includes support truss, steel-concrete shear wall or frame tube composed of simplified, dense column and deep beam, steel-concrete composite structure, etc. The different combinations of lateral force resisting system and gravity resisting system determine the structural form of multi-high-rise steel structures.
The common quality of steel structure and its causes: ① The cause of deformation of the transportation and stacking of the components: the deformation of the components due to welding during the production or the deformation of the components due to collision during the transportation process. It is generally corrected by jack or other tools or after baking with oxygen acetylene flame. ② The reason for the distortion of the component assembly: the joint steel does not match, and the gap is too large; The splicing process is unreasonable. If the section steel at the joint does not match, it should be straightened by oxygen acetylene flame baking or lever pressure. Assembly members should generally be equipped with assembly workbench, if assembled on site, it should be placed on a harder site and levelled with a level. When assembling, the full length of the component should be pulled through the line, and the representative point of the component should be levelled with a level, which is fixed by electric welding after meeting the design size, and the component should also be levelled after turning over, otherwise the component cannot be corrected after welding. ③ The reason for the inaccurate arch or production size of the member: the size of the member does not meet the design requirements or the arch value is small. When the component is assembled, the arch shall be lifted according to the regulations, and the size of the component shall be within the permissible deviation range.
2 Quality control of nail welding construction of building steel structure
2.1 Construction Preparation
The preparation work of building steel structure welding construction includes four aspects of preparation, and technical preparation, material preparation, construction machinery preparation and working conditions preparation. First, technical preparation. Before the construction, the selection of the welding process of the steel structure requires the evaluation of the construction unit, and the deepening of the design drawings based on the actual situation of the construction project and the process evaluation results, and the preparation of construction operation guidance on this basis. Before the construction of steel structure welding, the designer and the construction personnel need to carry out technical disclosure work. Secondly, the preparation of materials. Different stud installation will be in different positions, on the basis of fusion welding stud suitable for the porcelain ring can exist in two weeks, including penetration type porcelain ring and ordinary porcelain ring. If the direct pin is directly on the molded steel plate, then the penetrating porcelain ring should be used; If the bolt is installed on the steel beam, then ordinary porcelain rings should be used. Before construction, the construction personnel need to carry out baking dehumidification operations, which must be carried out under working conditions. Thirdly, the preparation of construction machinery and equipment. In the process of stud installation and construction, the fuse welding stud machine is the main tool used, and the Angle polishing machine is a common auxiliary tool in the construction process. In addition, in the process of welding stud construction, it is also necessary to arrange a medium-sized welding machine with good welding process as a supporting measure, and its main function is to repair welding of stud. Finally, the preparation of working conditions. Before welding the building steel structure, the operator needs to clean the paint on the steel surface, and it is also necessary to ensure that there is no rain and oil and other factors have a greater impact on the quality of the welding joint, and it is best to carry out the welding work of the building steel structure when the air humidity is below 85%. Based on the specific working conditions of the construction site, it is necessary to properly bake and dehumidifying the peg and the porcelain ring used in the matching.
2.2 Construction Technology
In order to effectively ensure the quality of welding construction of building steel structure, before welding construction, it is necessary to test welding materials, the main purpose of doing so is to detect whether the quality of welding materials is qualified, and whether there are defects and deficiencies in welding tools. After the welding construction is completed every day, the welding construction personnel need to select two bolts on each beam and use a hammer to bend it to 30°. If the naked eye can not see the existence of cracks, then the construction quality of the welding is up to standard. If there are not full or repaired bolts, it is necessary to use a hammer to bend it, the bend is controlled at 15°, and then the welding construction quality inspection.
2.3 Inspection during welding
It mainly includes the inspection of welding parameters such as welding current, voltage, gas flow and welding speed. The second is the cleaning of the welding layer, the control and inspection of the temperature between the layers. Then it is the control inspection of welding sequence. At the same time of inspection, inspection records should be made to form welding inspection documents. The inspection in the welding process is the most important link in the welding process, which has an important impact on the formation of steel structural parts directly. Therefore, the quality inspection unit should be familiar with the welding process, welding specifications and design requirements, select the appropriate inspection control point, can minimize the rejection rate, reduce rework, and achieve the welding quality goal.
2.4 Quality Inspection
Welding nails and steel welding should be conducted welding process evaluation (the results should meet the design requirements and the current relevant national standards), porcelain rings should be baked according to its product specifications, the inspection quantity is full inspection, the inspection method is to check the welding process evaluation report and baking records. Welding nails should be welded after the bending test inspection (the weld and heat affected zone should not be visible cracks), the number of inspections is 10% of each batch of similar components and should not be less than 10 (in the random inspection of components, each piece should be checked 1% of the number of nails and should not be less than 1), the inspection method is to be bent 300 with an Angle square inspection or observation inspection. The weld at the root of the welding nails should be uniform after welding (the welding feet that are not partially fused or less than 360° on the facade of the welding feet should be repaired), and the inspection number should be 1% of the total number of welding nails and not less than 10, and the inspection method is observation inspection.
Closing remarks
In summary, in the construction process of construction projects, steel structure is widely used in the frame structure of construction projects because of its many advantages, and has achieved good results. The welding construction quality of steel structure has an important impact on the construction quality of building steel structure, which will also have a greater impact on the stability of the overall building structure. Therefore, the welding quality of steel structure needs to be effectively controlled to ensure the quality of welding filler materials and improve the reliability of welding construction, so as to ensure the stability and safety of building steel structure. Promote the further development of China’s building industry.