Construction technology of steel structure in super high-rise building engineering?

1 preparation before hoisting of steel structure members

Super high-rise buildings are generally located in the city center, and the construction site in the city center is generally narrow. For the steel structure construction of super high-rise buildings, preparations such as entry, acceptance and stacking must be done before hoisting of steel structure members, otherwise it will have a serious impact on the hoisting construction of the whole project. Take the construction of a super-high-rise steel structure as an example. Due to the large number of steel structure members and limited space, they need to be stacked. In this case, if a detailed plan is not made for the sequence and stacking of the members entering the site, the members that want to be hoisted may be pressed down by other members during hoisting, or the members that need to be installed immediately have not entered the site, but the members that are pulled into the site are not wanted to be installed now, which will lead to repeated overturning and reverse transportation of the members, resulting in confusion in the placement of the members on the construction site. There are more than 1, steel members in the main building of this super high-rise building. Before construction and installation, the project department has formulated a detailed construction and hoisting scheme, numbering each member. For each numbered member, its shape, weight, installation position, entry sequence and adjacent member numbers are explained in the scheme. According to the hoisting scheme, the acceptance before hoisting is strengthened, and it is absolutely not allowed to enter the site and pile up without the established scheme.

2 Selection, arrangement and installation of vertical transportation equipment for steel structure members

2.1 Selection of vertical transportation equipment. There are a large number of steel structure members in this project, and there are a large number of super-high, super-long, overweight and eccentric members. In order to ensure the successful completion of the hoisting work of steel structure members in this project, the core work is to select vertical transportation equipment that meets the hoisting scheme of this project. When selecting vertical transportation equipment, the building size, site conditions and comprehensive consideration should be given.

2.2 arrangement of vertical transportation equipment according to the site conditions, building shape and structural layout of the project, taking into account the vertical transportation tasks and schemes, as well as the situation that two or more cranes with super-long, super-large, overweight and eccentric components are hoisting at the same time, after detailed calculation, two internal climbing tower cranes are arranged in the core tube, and jack-up tower cranes are arranged around the skirt building to meet the needs of the whole project working floor plane.

2.3 in order to improve the efficiency of vertical transportation, an auxiliary system of external power (the way of hoisting the shoulder pole by the winch) was adopted in the construction, which solved the climbing problem of the second tower crane well and played a decisive role in advancing the construction period; The installation and removal of large-scale internal climbing tower crane has always been a subject with complex technology and difficult construction in China. This project has studied a set of methods specifically for the removal of large-scale internal climbing tower crane. Practice has proved that this method is safe and feasible, which not only successfully solves the problem of tower crane removal in this project, but also tries to use internal climbing tower crane for similar projects in China.

3 hoisting of steel structural members

hoisting of structural members is the key process of steel structure construction, and the speed and efficiency of hoisting are the key to the success or failure of the whole project construction. In the construction of the main steel structure of this super-high-rise building, due to the tight construction period and huge hoisting quantity, the project adopts the methods of regional hoisting, sorting and double-machine hoisting, which not only ensures the construction period, but also solves the hoisting problem of large mast in the state of overweight, eccentricity and superelevation.

4 positioning measurement of steel structure members

In order to ensure the positioning accuracy of the steel structure members of the main building of the super-high-rise building and the absolute accuracy of the verticality and axis elevation of the whole project, the project department has formulated a special measurement scheme with ultra-high standards to ensure the construction quality of the steel structure of the project and provide a reliable basis for construction inspection. The installation of steel structural members of super-high-rise buildings is different from ordinary buildings. The installation of steel structural members of super-high-rise buildings not only directly affects the quality of the whole project, but also has obvious influence on the construction period due to the huge number of members. If the positioning measurement scheme is unscientific and unreasonable, although the positioning is accurate and the verticality and axis elevation control of the project meet the requirements of the measurement scheme and specifications, the installation, review and correction time of each member will be prolonged, which will greatly affect the construction period of the whole project. In this project, the installation process, installation time and the internal relationship between various components are fully analyzed. Through induction and sorting, modern high-tech measuring equipment is fully utilized, and standardized measuring processes similar to standardized assembly lines are classified and zoned. Personnel, posts, areas, time, types of work and scope are specially responsible for the measurement work within their own scope, and they will go to work after the drill. As far as possible, the construction time delayed due to improper measurement work is reduced, and the rework and secondary installation caused by measurement errors are basically eliminated. Through the process summary of measurement work, the original "overall correction" method is changed to "process tracking correction" method, which greatly saves the construction time while ensuring the engineering quality.

5 welding of steel structural members

Super-high-rise steel structures have the characteristics of large volume, various types, complex structure, large engineering quantity and high quality requirements. As an important process of steel structure construction, laying out and welding raw materials for steel structural members, the welder's level, training and process selection during welding are powerful guarantees for the "safety, high quality and high efficiency" of the project. The height-width ratio of this super-high-rise building is 1∶9, which is rare in China. In order to ensure the structural safety, the project department carefully and deeply studied the design documents, classified the steel structure components in the design documents, and established a steel structure component lofting, blanking and pre-assembly factory. The welding operation in the factory can be completed on the standardized welding production line with modern high-tech welding equipment as far as possible, and the convenience of horizontal and vertical transportation is fully considered, so as to reduce the welding operation on site as much as possible. That's right, the welding workload on site is also amazing, so the project set up a welding QC team, used all available tools and means to invent, create and learn from each other. In view of the welding task of this project, combined with the high-altitude parts and suspended parts of components to ensure the feasibility of safe operation and construction protection, the semi-automatic welding process with mature technology of CO2 gas protection was improved, which fundamentally solved the welding problems such as vertical welding, oblique vertical welding and fillet welding, and ensured the whole steel structure.

6 How to solve the contradiction between construction period and quality

Compared with ordinary concrete buildings, super-high-rise steel structures are characterized by a large number of components, tight construction period and high quality requirements. How to solve the contradiction between quality and construction period depends not only on scientific management, strict construction organization and factory-style component pre-assembly, but also on boldly applying new technologies, new processes and new equipment suitable for this project according to the engineering characteristics as much as possible. There are 15, bonuses for the main steel structure members of this super high-rise building, weighing about 25, t, and the quantities of profiled steel plates, welding studs and welds are tens of thousands, so the construction period is particularly tight, and the contradiction between the construction period and quality is particularly prominent if it meets the quality standards of European norms and needs to be completed on time according to the construction period agreed in the contract. In order to solve the contradiction between construction period and quality and ensure the "safety, high quality and high speed" of the project, it is necessary to establish a scientific management organization system. To this end, the project has set up a project management department, which is constructed in strict accordance with the project management law, and implements the project manager responsibility system and full contract management.

7 safety management

Safety means progress, and safe construction will bring benefits. Without safety, nothing can be said. The safety management of this project focuses on aerial work, including aerial falling, aerial welding spark protection and falling objects, which is very dangerous in construction. Therefore, we adhere to the 16-character policy of "strict requirements, standardized operation, prevention first, and prevention of minor delays" in grasping safety work, and put an end to safety accidents. First, the director of safety education should make unremitting efforts to emphasize the importance of safety in production every time, whether it is a general meeting or a small meeting; In the eye-catching place on the construction site, slogans and warning signs are hung to remind employees to pay attention to safety in production, and the safety awareness runs through every working procedure and everyone.

the second is to strengthen the leadership of safety work. The project department sets up a safety work leading group, clarifies the responsibilities of leading groups at all levels to ensure safety work, and signs a letter of responsibility for safety work, so that safety work is managed by people everywhere. The third is to strengthen safety training, formulate a complete safety production training system, select training content, determine training objects and conduct targeted training according to the safety characteristics of this project. The fourth is to do a good job in safety protection. In order to ensure the personal safety of employees, all kinds of safety protection articles are distributed to employees in time, and a strict safety protection system is formulated. When entering the construction site, you must wear a safety helmet; Safety belts must be worn for aerial work. Fifth, pay special attention to the inspection and implementation of safety work. The leaders of the project department and the construction team will take turns to be on duty at the construction site for 24 hours, and work with the safety officer to eliminate all kinds of hidden dangers in time. At the same time, carry out "three inspections" regularly, that is, check whether the operation is standardized, check whether the protective measures are in place, and check whether the potential safety hazards have been eliminated, so as to ensure that the inspection does not leave gaps or dead ends.

8 Conclusion

With the rapid development of super-high-rise building technology, the construction technology of super-high-rise buildings in China has also been significantly improved. How to improve and optimize the problems encountered in the construction process is still an important issue for our practitioners to think about at present.

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