In the field of architecture, the superiority of steel structure engineering is more and more recognized by people, and the quality problem is also paid more and more attention. It is of practical significance and necessity to strengthen the construction quality supervision of steel structure engineering.

Keywords steel structure quality supervision and control

Because of its low cost, good structural performance and fast construction speed, a large number of steel industrial workshops, residential quarters, high-rise buildings and bridges have appeared one after another, replacing the traditional brick-concrete structure and concrete frame structure. Because steel structures are widely used in the construction field, the construction quality directly affects the safety of engineering structures. How to control the quality of engineering construction has attracted the attention of people in the industry. Therefore, it is particularly important for supervision engineers to control the construction quality of steel structures. Combined with practice, this paper discusses some experiences of steel structure construction quality control in the process of supervision.

1, set up a reasonable project supervision organization for the project and carefully prepare the supervision plan.

1. 1 Set up a reasonable project supervision organization and do a good job in the later construction. The project supervision organization is the organization that the supervision company sends to the site to supervise and manage the project quality, progress and investment. The project supervision organization must be established according to the characteristics, scale and technical complexity of the project, with well-equipped professionals, reasonable structure and sufficient quantity to meet the needs of the supervision site, and equipped with necessary testing tools at the site. At the same time, it is necessary to strengthen the on-site post construction and image construction, improve the on-site management system and methods, standardize the behavior of supervisors, ensure that supervisors can perform their duties, and improve the work efficiency of supervision institutions.

1.2 Prepare the supervision plan according to the engineering characteristics. Supervision planning is a guiding document for project supervision institutions to supervise project implementation. The perfection of supervision planning affects the implementation of engineering supervision to a certain extent. Before the project starts, the project supervision organization shall organize the supervisors to compile according to the characteristics and scale of the steel structure project, clarify the procedures, measures and methods of "three major controls" in the supervision process, and organize the supervision work in strict accordance with the contents and requirements of the supervision plan in the supervision process.

2, do a good job of preparation before the project starts.

2. 1 Strengthen the joint review of construction drawings. Drawings are the basis of engineering construction. Before the project starts, the project supervision institution shall organize the supervisors to be familiar with the specifications, standards, processes and technical conditions related to the engineering drawings, and fully understand the design intent. At the same time, it is necessary to organize the professional and technical personnel of the construction unit to jointly review the drawings, check the "mistakes, leaks, bumps and gaps" in the construction drawings, strive to solve the problems before construction, and reduce the impact of drawing problems on the quality and progress of the project.

2.2 Carefully review the organization design of steel structure installation and construction. Construction organization design is the technical document for the construction unit to comprehensively guide the project implementation, and the perfection of construction organization design directly affects the quality and progress of the project. Therefore, the review of construction organization design of steel structure installation project should be targeted and targeted. The main contents of the review are:

(1) Establishment of quality assurance system and technical management system;

(2) Special type of work training certificate and employment certificate;

(3) Application of new technologies;

(4) the pertinence of the project;

(5) Measures and methods for quality and schedule control;

(6) the arrangement of the construction plan (time limit);

3, strengthen the quality supervision in the process of on-site construction.

3. 1 Quality control of steel structure foundation engineering. The foundation of steel structure engineering generally adopts concrete independent column foundation, and the construction procedures and methods of concrete, steel bars and formwork of the foundation are the same as those of other projects, and the bolts embedded in the independent column of the foundation are the focus of quality control. The distance and height deviation between a single bolt and each group of bolts directly affect the installation quality of steel structure engineering. In the process of supervision quality control, we asked the construction unit to take the following measures and achieved good results.

(1) Make the installation template. Take three steel plates (two 20mm thick and one 8~20mm thick) with the size of steel column bottom plate, drill two 20mm thick steel plates according to the position and size of bolt holes in steel column bottom plate, assemble three steel plates, insert a group of bolts into bolt holes, and weld the bolts into a whole with Ф14 ~ Ф16 steel bars, one at the top.

A: Ф14 ~ Ф16 reinforcement B: bolt C: Ф14 ~ Ф16 reinforcement E: 20mm steel plate F: 8 ~ 10mm steel plate G: 200 ~ 300mm H: 50.

Figure 1

(2) Fixation of bolt group. Before concrete pouring, use theodolite to accurately locate bolt groups, weld Ф14 ~ Ф16 steel bars on the column main reinforcement, and fix the steel bar ends of bolts on the formwork, one at the top and one at the bottom, so as to control the spacing and height of each bolt group within the allowable error range. At the same time, the bolt thread is protected from being damaged during concrete pouring.

(3) completes the intermediate handover. After the completion of civil engineering, use theodolite to measure the distance between bolt groups (axis distance) and the pouring height of each column. After our retest acceptance, we will organize civil engineering and steel structure installation units to carry out intermediate handover acceptance, and require steel component installation units to carry out retest after acceptance.

3.2 Quality control of steel structure main project.

(1) Quality acceptance of steel members. The processing of steel members has been industrialized, so it is very important to check the quality of steel members entering the site. In addition to checking the quantity according to the schedule, we also checked the appearance, geometry and certificate, and checked the following information:

(1) steel material retest sheet (original);

(2) Material certificate of steel (the copy must be stamped with the official seal of the production unit, and the original should also indicate the storage location);

③ NDT report (original).

(2) Installation quality control of steel members. When installing columns and beams, mainly check whether the pad iron under the column bottom plate is flat, whether the column is vertical and displaced, the vertical, straight and lateral bending of the beam, the tightening degree of bolts and the cleanliness of the friction surface. Hoisting can only be carried out after acceptance. The steel structure is installed to form a spatial fixed unit. After the acceptance, the construction unit is required to pour expansive concrete between the column bottom plate and the top surface of the foundation for secondary compaction.

(3) Quality control of bolt installation. In steel structure engineering, high-strength bolts and ordinary bolts are generally used for bolt connection. One end of each bolt shall not be padded with more than two gaskets, and the bolt hole shall not be reamed by gas cutting. After the bolt is tightened, the exposed thread shall not be less than two pitches. Before using high-strength bolts, the certificate of approval and retest sheet of bolts should be checked. During installation, the contact surface of plate stack should be flat, the contact surface must be greater than 75%, the edge clearance should not be greater than 0.8 mm, and high-strength bolts should be able to penetrate freely without knocking or reaming. High-strength bolts shall not be used as temporary installation bolts, and the bolts shall be tightened in one direction. Those installed on the same day should be finally tightened and checked one by one. Undertightening or overtightening shall be repaired or replaced.

(4) Welding quality control. Before welding the steel structure, check the certificate of covered electrode and use it according to the instructions. There shall be no cracks and flash on the weld surface, no blowholes, slag inclusions and arc pit cracks on the first and second welds, no undercut and incomplete penetration on the first-level weld, nondestructive testing shall be conducted on the first-level and second-level welds as required, and the welder's steel seal shall be checked at the specified welds and positions. Unqualified welds shall not be treated without authorization, and shall be treated after the modified process is determined. The number of welds in the same position shall not exceed 2 times.

(5) Quality control of painting engineering. Before painting the steel structure, there should be no foreign bodies such as welding slag, oil stain, water and burr on the surface of painted components, and the number and thickness of painted edges should meet the design requirements.

3.3 Quality control of door and window installation. There are two key points to control the installation quality of steel windows. A, steel window approach certificate, product inspection report and appearance inspection. Secondly, the clearance control between the steel window and the column that fixes the steel window. First, it is necessary to construct a column to fix the steel window, which may cause the gap between the steel window and the column to be too large or the steel window cannot be installed. In the process of supervision, we require the construction unit to fix the column on one side of the steel window first, and then weld the column on the other side after the steel window is completely fixed in place to ensure that there is no gap between the steel window and the column.

3.4 Installation quality control of profiled color plate. After the profiled color plate enters the site, it is necessary to check the appearance and certificate, and check the installation accuracy of steel members related to the construction and installation of profiled steel plates. During the installation of purlins, weld burrs and splashes are removed, and antirust paint is applied for anticorrosion treatment. When installing color plates, typesetting should be carried out according to the wall surface. Starting from one end, the plates must be clenched and then fixed with screws, and the joints of wallboard should be waterproof.

4. Concluding remarks

The construction of steel structure engineering has just started in China. In the process of steel structure engineering construction supervision, in order to give full play to the role of engineering supervision, the supervision engineer should not only do a good job in the process acceptance of each sub-project, but also strengthen supervision and inspection in the construction process to ensure the construction quality of steel structure engineering.