With the continuous development trend of contemporary economic development, steel structure engineering project has been widely used in the engineering project industry for its advantages of faster construction speed, short cycle time, high compressive strength, conducive to prefabricated components, installation, usable high-rise residential long-span, etc.In the past, many of our country choose concrete structure and prestressed reinforced concrete, and the professional technical personnel of on-the-spot engineering project are lack of engineering construction experience of steel structure engineering project, and the quality of construction immediately endangers the safety of engineering project structure.Therefore, the product quality problems of steel structure engineering projects have caused more and more attention. Therefore, it is of great practical significance and importance to improve the quality management of steel structure construction. 

Key points of construction quality control

1.Construction preparation

Construction preparation is an essential standard for capital construction engineering construction. It plays a key role in making full use of human basic contradiction, effectively organizing human resources and material resources, accelerating construction progress, showing construction quality, saving project investment and raw materials, and successfully completing the daily task of steel structure capital construction.

1.1 Do a good job in the preliminary examination and safety disclosure of engineering drawings

Engineering drawings are the basis of building construction. Project leaders of construction projects should organize relevant professional and technical personnel to review and digest and absorb engineering drawings. The first purpose is to make construction enterprises and enterprises understand the design drawings, master the characteristics and design intent of engineering projects, find out the bottleneck problems that must be solved, and formulate solutions; the second is to facilitate the processingThe defects in engineering drawings can reduce the errors and omissions of engineering drawings, and solve the quality and safety hazards in engineering drawings in the embryonic stage.In addition, the safety technical disclosure should be done well, the integration of engineering construction and design scheme, the integration of steel structure lifting and civil engineering, steel structure and concrete structure prefabricated components should be done well.

1.2 Construction deployment of steel structure construction

The design scheme of construction plan is the key comprehensive technical document for guiding all kinds of theme activities in the whole process of construction, which is a scientific research management scheme.When the construction enterprise formulates the construction plan and the project construction scheme, it is necessary to formulate effective practical implementation measures from the five levels of human, machine, material, method and environment, implement the scheme, implement the organization staff, implement the self inspection, mutual inspection and final inspection, list all the product quality problems that are very easy to occur into the controllable situation, and ensure that the technical measures of the plan scheme are powerfulIt works.In the process of compiling and implementing the construction plan and design, it is necessary to ensure the general and deep-seated scientific research, make safety disclosure to the construction team, and ensure that everyone strictly checks.The steel structure project should make the processing technology and installation construction plan design scheme for the manufacturing and installation links respectively.The content of processing technology should include the product quality standards and technical standards of each process flow, each sub project, and various specific methods to ensure the product quality.The construction deployment of steel structure installation construction includes the establishment of quality assurance management system and technical system management, the countermeasures and methods of quality and progress control, and the allocation of construction period.  

2.Attach great importance to the quality management of steel structure foundation engineering 

The quality management of steel structure foundation engineering generally refers to the quality management of steel structure basic embedded bolt. The embedded bolt is the first step of all building construction, and also a very important step, which is the basic of all engineering projects.When the bolts are embedded in the project construction, we should first understand the engineering drawings, master the intention of the engineering drawings, and make the installation template.The embedded bolt is accurately positioned on the beam main reinforcement and template of the column head with two installation templates and construction reinforcement, so as to ensure that the embedded bolt will not be moved by the construction of civil engineering pouring concrete engineering.In this way, the interval and height of each group of anchor bolts can be controlled within the allowable deviation range; in addition, the screw mouth of anchor bolt shall be well maintained to prevent damage during cast-in-place concrete.After the completion of civil construction, recheck the design elevation and center line of anchor screw with level instrument and level instrument, and make records.And submit the next process engineering acceptance.

3.Steel structure manufacturing engineering construction quality control

The construction of steel structure engineering project generally goes through two stages: fabrication in processing plant and installation on site.Most of the time of steel structure engineering project is carried out in the factory workshop. Because the quality of steel structure prefabricated components in the processing plant is good or bad, it is particularly important for the on-site installation of steel structure engineering project and the safety and stability of the overall structure.Therefore, the steel structure manufacturing business must have relative company qualification, production scale, technical working ability, industrial equipment and excellent technical level. 

The general manufacturing and production process of steel structure is divided into: construction setting out → cutting → plate assembling → laser cutting → tower assembling → arc welding → drilling → assembling → correcting and forming → riveting parts cutting → manufacturing and assembling → welding and welding detection → antirust treatment, spraying and serial number → acceptance of prefabricated member project.In the fabrication of steel structure, we should grasp the important technological process and carry out quality management according to the production process of steel structure, such as the production and processing of important parts, the processing technology and Countermeasures of key prefabricated components, the selected production equipment, processing technology and weapon equipment, etc. 

4.Attach great importance to the construction quality control of electric welding engineering

In the steel structure manufacturing and equipment installation engineering project, the electric welding engineering project is the most important stage, so we must attach great importance to the construction quality control of welding engineering.At present, most of the steel structure in the process of processing with automatic submerged arc welding machine, part of the full-automatic gas shielded welding machine, some parts of the selection of manual welding.

There are many quality problems of electric welding products, such as welding scar, weld bead, air hole, incomplete penetration, wrong joint, wrong joint, large welding specification error, no need for arc striking plate, no correction of welding deformation, and unclean spatter removal.Due to this kind of situation, before welding of steel structure, the qualification certificate of welding wire shall be inspected and applied according to the provisions of the use instructions. The electric welding worker must have a work license. There shall be no cracks and welding scars on the welding surface. There shall be no blowholes, weld beading, arc pit cracks in the first and second level welding, and the defects such as wrong joint and incomplete penetration are not allowed in the first and second level welding. Nondestructive testing technology shall be carried out for the first and second level welding according to the requirementsIn the required welding and position, the welder’s anti-counterfeiting mark shall be checked.The unqualified welding can not be handled by ourselves, and it can be solved after changing the processing technology. The welding repair frequency at the same position is not suitable for more than two times.

5.Installation quality management of steel prefabricated components

After the completion of the project, the steel structure will be installed on site.Before the installation of steel structure, the quality of prefabricated components shall be inspected. When the permanent deformation and defects of prefabricated components exceed the control value, solutions shall be carried out.

For the installation of steel beam, check whether the cushion block under the column bottom plate is padded and paved to avoid the imbalance of the anchor screw under the column bottom plate; whether the control column is vertical and whether there is deviation; in the equipment installation engineering, before the structure does not produce a stable management system, the temporary bolt support strategy should be adopted. 

When the steel structure installation produces the indoor space fixed fixed module, and the project acceptance is up to standard, the construction enterprise is required to immediately pour the secondary concrete density of the column bottom plate and the interior space of the basic wall top with expansive concrete.Finally, it is necessary to check the flatness of the main works of the steel structure and the bending of the overall plan. 

6.Quality management of steel structure standard parts connection

The key to the quality management of steel structure standard parts connection is to pay attention to the quality management of high strength bolt connection.The construction quality of high strength bolt connection project is controlled from the following aspects:

6.1 The first steel structure project must pay attention to the production and processing quality of high strength bolt friction surface and the maintenance before installation to avoid environmental pollution and rust.Before installation, carry out the load index test on the friction surface of high-strength bolts, check the original factory certification and production batch number of high-strength bolts, and conduct axial force test for high-strength bolts with different production batch numbers on time. 

6.2 The installation of high-strength bolts is required to be penetrated at will without knocking and reaming. Therefore, certain jig grinding tools should be prepared in advance to control the deformation of the steel structure, and the effective fixed fixed countermeasures should be adopted to ensure the reliability of the specification when the prefabricated components are transported.

6.3 During the whole process of steel structure installation, the surface of thick plate stack should be leveled, the surface must be more than 75%, and the edge clearance should not exceed 0.8 mm.Strictly control and inspect the installation and processing technology of high-strength bolts, including the actual operation sequence, installation method, tightening sequence, initial tightening and final tightening, and the torque wrench for tightening anchor bolts shall be calibrated.Check one by one at the end of final screwing, and make up or replace those under or over screwed.

7.Steel structure anti rust treatment and spraying project

Anti rust treatment and spraying of steel structure are easy to be ignored in current steel structure project.The rust prevention treatment of steel structure is divided into manual service rust prevention treatment and mechanical equipment rust prevention treatment. The construction team should select different rust removal methods according to the engineering drawings and rust removal grade.The operation of the construction quality of the brush coating project shall ensure that before the steel structure is painted, the surface of the prefabricated components shall be free of welding penetration, oil stains, water and burr, and the brushing process and thickness shall meet the requirements of the design scheme.The spraying raw materials must have the certificate of qualification, and the fire-proof material spraying project must be carried out by the construction enterprise approved by the fire safety position.

8.Color steel tile construction quality control

Color steel tile project is another key part of steel structure engineering project.The quality of its construction is harmful to the application of steel structure project.At present, there are many types of color steel tile.

However, the construction problems of color steel tile project are more centralized, such as: the joint of color steel plate, the manufacturing and installation of color steel plate parts and other connection points are not carefully and reliably solved, the maintenance structure is leaking, the perceived quality of color steel plate is not even, deformation, scratch, environmental pollution, etc.

Therefore, the key to the quality management of the color steel plate installation of the profiled plate includes: after the color steel plate enters the site, it is necessary to carry out the inspection of the appearance and certificate of conformity, and check the installation precision of the prefabricated steel components related to the construction and installation of the profiled steel sheet, eliminate the welding core and spatter during the installation of the steel purlin, and brush the anti-corrosion paint to solve the problem.During the installation of color steel plate, effective installation and processing process sequence should be set.