As an important part of the construction industry, the building steel structure industry plays an increasingly important role in the construction market. With the rapid development of China's social economy, the steel structure industry in China has also developed rapidly. In the production process of building steel structure, it has the following advantages: short construction period, light environmental pollution and good economic benefits. Due to the above reasons, the market demand for steel structures is increasing, and the application scope is also getting wider and wider, such as factories, museums, stadiums and other high-rise buildings. Many research achievements in the processing, manufacturing, installation and construction of building steel structures have played a positive role in promoting the level of the whole steel structure industry.

2 the concept of steel for steel structure in building engineering

2. 1 steel for steel structure

Steel structure is a structure in which steel, such as section steel, steel plate and steel pipe, are connected by means of bolts and riveting after proper processing, which makes it have certain uses and functions. Broadly speaking, the classification of steel structures includes: buildings, bridges, offshore platforms, ships, pressure vessels and other steel structures. Specifically, building steel structures include: high-rise, heavy-duty, light-duty, mixed steel, long-span and residential steel structures. Carbon steel and low alloy steel with strength less than 460MPa are widely used in beam, column and truss structures of building steel structures.

2.2 Steel for building steel structure

Steel plates with a thickness of 6-8mm are generally used in building steel structures, and only a few buildings use ultra-thick plates with a thickness of100 mm. The classification of steel plates also includes: cold bending, corrugated plate, hot rolling H, welding H, building cast steel, steel pipe and steel bar. There are more than 40 steel and steel-related standards, including GB/ T700, G B/ T 19879, GB/ T53 13, GB/ T 159 1, GB/T S/699. Q345 high strength steel is often used in steel structure engineering in China.

3 building steel structure processing strategy and technical measures

This paper takes the newly-built gymnasium in Xining and the maintenance depot and side span of Xining Station as the research objects. The most complicated part of engineering construction is the roof, which is not only steep, but also adopts steel tube truss structure. Joints on trusses in different parts are welded, and local joints are cast. Intersecting welded trusses are the steel structures of most roofs. The main components of steel structure include: steel tube truss, welding bracket and roof purlin. Steel tube truss is the key point of this project, and the most important production process is the construction design drawing and the bending of chord.

3. 1 key measures of processing and manufacturing

The key technologies of steel structure fabrication are as follows:

(1) The web is connected with the chord. In order to ensure the quality of assembly and welding, the intersecting line and groove at the pipe end are cut by linkage NC intersecting wire cutting machine.

(2) cold rolling bending is adopted, and bending is formed on a pipe bender to ensure the formation of an arc curve;

(3) Improve the manufacturing degree of steel structure in the factory and reduce the workload of on-site construction personnel;

(4) The key is welding. Strictly formulate the welding process plan, improve the requirements of welding and on-site welding of intersecting nodes, and check the post-welding condition in strict accordance with the regulations;

(5) The steel pipe truss is fabricated and pre-assembled in sections in the factory. After the technicians pass the inspection, the steel structure shall be painted, marked and packaged. After the steel structure is transported to the construction site by truck, it will be assembled as a whole.

3.2 Analysis of key points of steel truss manufacturing process.

3.2. 1 blank

(1) blanking: In order to ensure the dimensional accuracy and vertical section of steel structure, the steel pipe needs to be mechanically cut during blanking to ensure the smooth blanking work;

(2) Groove: the butt welding of steel pipes is cut by a pipe groove machine or directly by a numerical control intersecting wire cutting machine;

(3) Docking: In order to save materials, the designer will omit the joint of the upper and lower chords, which does not meet the requirements when docking. In this case, it is necessary to communicate with the designer and adjust the joint position to meet the design.

3.2.2 Cutting of pipeline intersecting lines and grooves

The branch pipe is connected with the main pipe, and the intersection line and its groove are mainly cut at the end of the branch pipe. When the wall thickness of the branch pipe is greater than or equal to 6 mm, the groove can not be cut when it is less than 6 mm. In the summary of the engineering construction process, the cutting process of the branch pipe needs to consider the influence on the cutting trajectory, and the construction personnel should avoid manually correcting the cut branch pipe when cutting steel.

angle pipe

The process requirements of elbow are as follows:

(1) The steel pipe used in the project shall be free of creases, and the curved rod face shall meet the requirements of smooth transition;

(2) The material of the formed elbow has no obvious change;

(3) The outer diameter and wall thickness of the formed elbow must be limited to 65438±0mm;

(4) According to the specification requirements and the curvature of the steel pipe, the steel pipe is formed by mechanical rolling.

weld

JGJ8 1-2002 specifies the requirements of welding specifications for steel structures. When welding steel structures, relevant preparations must be made. First of all, the construction unit must do a good job in evaluating various materials, such as steel, during the welding process. The construction unit shall determine the welding process of construction according to the evaluation report.

0+0 groove structure

(1) Weld structure of intersection line: mainly located between horizontal web and anti-glare bar, or between web and upper and lower anti-glare bars. In the welding process, the intersection forms include oblique and orthogonal forms.

(2) According to the different butt joint forms of steel pipes, a bushing can be added for welding, which is a first-class weld. The breach of the weld is machined, and the breach can be cut by numerical control cutting machine.

(3) welding. The inspection requirements for welds are as follows: when inspecting welds, the appearance inspection should be carried out first; Magnetic particle detection is applied to fillet weld; Ultrasonic flaw detection can be applied to weld and penetration weld, and can also detect penetration weld; According to the welding material and position, choose welding auxiliary materials.

When welding steel, construction must be carried out in accordance with the construction drawings and relevant national specifications. First of all, do a good job in process evaluation before welding, and make welding strategy according to the evaluation results. The national specification requirements of welding technology include JGJ8 1-2002 and JB4708-90. Symmetrical welding is often used in welding construction. In order to ensure the deformation and shrinkage of welded parts, workers must work in a reasonable welding sequence. The acceptance and inspection process of generated wave flaw detection shall be implemented according to the relevant provisions of GB 1 134-89, and the welding quality requirements shall be implemented according to the relevant provisions of GB5022 1-95.

3.2.5 Process test evaluation

When the construction unit carries out welding construction, the construction personnel must first formulate the welding technology, and the welding personnel must work in strict accordance with the welding construction technology to ensure the smooth progress of the work. The following describes the welding process testing and evaluation:

(1) Conduct process tests on different welding materials according to the requirements of relevant national codes, determine the construction process according to the test results, complete the process instruction and complete the actual welding guidance;

(2) According to the national standard JGJ8 1-2002, determine the welding work of steel pipe and supporting hinge;

(3) When welding steel plates, workers must avoid the delamination of steel plates, so the following measures are taken: 1) When using Z 15 grade steel plates, the area shrinkage and sulfur content must be limited within a certain range; 2) Technological measures that can be taken include preheating and post-heating temperatures; 3) The welding level and sequence must be reasonable; .

Internal assembly

The assembly of steel structure is a very important work in the factory. The specific assembly work is as follows: firstly, the single steel structure is manufactured, and then the whole assembly is carried out, and the working process is carried out on the steel platform. When assembling the steel structure, it is necessary to install the clamping fixture, and after the installation is completed, the corresponding inspection work must be carried out.

4 conclusion

The structural system of the engineering project adopted in this paper is complex and its manufacturing technology is relatively high. Its steel structure manufacturing technology has no ready-made norms and standards, which is a great challenge to the construction unit. This construction project is based on design drawings and combined with previous construction experience. Through comprehensive management, the construction links are saved and the smooth completion of this project is ensured.

I believe that after the above introduction, everyone has a certain understanding of the processing and manufacturing methods and technical measures of steel structures in construction projects. Welcome to Zhong Da for more information.

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